Written by Greg Gimlick
Demystifying the terms and technology used in electric flight
Technical
As seen in the February 2014 issue of Model Aviation.

It’s that simple! All you need to do is be able to rewrite Ampere’s Law using Stokes’ Theorem and you can get right into electric flight without any problem at all! Get online, grab your credit card, and enjoy the hobby!

That’s the way it feels to many people who are new to electrics and those of us who have been around the technology for a while are partly to blame. In our excitement and zeal for electrics, we tend to dump a ton of minutiae on newcomers to the point of running them off.

There is no way I can teach you all there is to know about electric flight in the next couple of pages, but I can get you started with a little effort and no fear.

Terminology

Don’t get bogged down and overwhelmed by the new vocabulary and terms. Here is a basic list of the most important terms and what they mean—in non-engineering terms.

• Volts: This a term with which most are familiar. Your automobile battery is 12 volts and your house wall sockets are generally 120 volts. You use 9-volt batteries in smoke detectors. Think of voltage as water pressure and if there is no pressure, there will be no water. Without voltage, our systems wouldn’t have the power to fly. This is abbreviated as “V.”

• Current: This is expressed in amps and is what makes things go. This is the electron movement through the wire and might be compared to water moving through a pipe. It is measured in amperes (amps) and abbreviated as “A.” In electrical equations you’ll see it as “I.” (That confuses new and experienced modelers.)

• Power: This is expressed in watts and what we refer to often. Watts and horsepower are different units for measuring the same thing: power (1 hp = 746 watts). Electric fliers use watts because input watts are easy to measure with a wattmeter. Gas or glow fliers use horsepower, because internal combustion engine output power is measured with a dynamometer (dyno), which can also be done with electric motors.

If you were to compare input watts with output horsepower, you would know the motor’s efficiency. We abbreviate it as “W,” but in electrical equations, the symbol is “P.”  The important thing to remember is that we determine power in our models by multiplying volts by amps and get the total watts our systems produce (P = IV).

• Resistance: This is expressed in ohms and abbreviated as the Greek letter “Ω,” but in our equations we use “R.” Think of resistance as a crimp in a hose causing a restriction. Low resistance is always our goal to make sure we get the most out of our systems.

• Gauge: This refers to the size of our wires in the system. It’s measured in American Wire Gauge (AWG), and the bigger the diameter, the lower the AWG number.  A 10 AWG wire is thicker than the 22 AWG we see on servos. A bigger wire means lower resistance.

• Power loading: When discussing the power in our electric airplanes, we refer to it as how many watts per pound are being produced. If our airplane weighs 5 pounds and we have 500 watts of input power, we have 100 watts per pound (500 watts/5 pounds = 100 watts/pound).

• Kv: This is a term commonly referred to when people discuss motors and is known as a motor constant, specifically voltage constant. It indicates how quickly the motor would turn at a given voltage if there were no internal resistance. It’s expressed as rpm/volt. When you see motors listing a Kv of 500, for every volt applied to the motor without a load (no propeller), the motor will turn 500 revolutions per minute.

• Efficiency: Being efficient is better, but when applied to our electric airplanes, it’s bantered about like the Holy Grail. Nothing is 100% efficient, but we do our best to reduce things such as resistance that affect our systems. I referenced input power earlier and efficiency is the ratio of input power to output power. For all purposes, we determine basic power requirements using input power.

• ESC: This is the electronic speed control that connects between the battery and motor. It is also connected to the receiver-throttle channel and controls the motor. It is generally rated by the number of cells and current the system can handle.

Castle Creations has a wide range of ESCs with clearly labeled ratings.

Battery Terminology

If you are using LiPo batteries, which have become the standard in electric flight:

• 3S, 4S, etc: Battery packs are made up of a number of cells in series and this number represents that. If the pack is listed as a 3S pack, then it has three individual cells connected in series within the pack, each with a nominal voltage of 3.7 volts. The pack’s total will then be listed as an 11.1-volt pack. A 4S pack would be 14.8 volts, etc. (4 cells x 3.7 volts = 14.8).

• Pack capacity: This is the capacity in either milliampere-hours (mAh) or amp hours (Ah) of the pack. A typical 3S pack might be listed as either 2,200 mAh or 2.2 Ah. A large pack with more capacity might be shown as 5,000 mAh.

• Discharge rating:“C” represents the capacity of the LiPo pack. Labels will typically show the discharge rating of the pack as 25C, 30C, or whatever the manufacturer believes the pack will handle during discharge without degrading the pack. Discharge ratings, sometimes mistakenly referred to as C-ratings, are often overly optimistic. A 2,200 mAh pack rated as a 30C pack, however, could be discharged at 66 amps (30 x 2.2 = 66) without being damaged. This is optimistic, but the number is a guideline. Packs with higher discharge rates have lower internal resistance, which is a good thing.

• Charging: The important thing to remember is to buy a balancing charger. This ensures that each cell within the pack matches the others. Get one that will do the maximum number of cells you expect to charge at the rated pack capacity. A 2,200 mAh pack would be charged at 2.2 amps, a 5,000 mAh pack would be charged at 5 amps, etc.

A 12S pack was made with two 6S packs in series for the Ag Wagon. Note that the label shows they are 6S and 5,000 mAh packs capable of 60C discharge.

I Thought It Was Simple!

It is! Electric power can be as complicated as you want to make it, and some pilots like to get into the details. But it can also be simple. You’ll see and hear the terms listed often and it’s important to have a basic understanding of them, but a degree in electrical engineering is unnecessary. You will appreciate knowing them if you call for technical support and the manufacturers begin asking questions.

If you want to try an electric airplane or helicopter and learn as you go, call a reputable hobby shop or online vendor and select a system that has been fine-tuned to work. There are plenty of glow-powered Plug-N-Play setups and most work well.

If you have an airplane that is powered by a glow engine, you can convert it to electric power without having to earn a degree. Many of the current kits on the market have already been converted by some of the manufacturers. You simply need to tell them what it is and get the system they suggest. Knowledgeable vendors can easily make recommendations if you give them some basic information about your conversion.

Figuring It Out Yourself

Most of us eventually want to understand our systems and how to figure out a particular one for a project. This is the section where you’ll see how easy it can be. The bar graph on the next page is a basic listing of requirements for various types of performance using power loading.

These guidelines make it easy to select the right motor, battery, and propeller combination for any project.

Motor Sizing Voodoo

If you’ve used glow- or gas-powered engines, or if you are new to RC, the motor-sizing nomenclature can be a nightmare. It’s also a nightmare for many experienced aeromodelers, so don’t despair. It is getting better, but there is no standard for naming motors in regard to capability.

In the glow-fuel world, you may be accustomed to seeing .40 or 1.20, etc., and in the gas world, 50cc, etc. Some manufacturers have tried to name their motors with similar names to equate them with the engines they replace. This is unpredictable, but most come close.

Another common naming method is to use the dimension of the outer case of the motor or the stator dimensions. This is a system I like, but I wish companies would agree to use either case or stator size as a standard and not mix them.

Motor stats tell us that X motor on Y volts will turn Z rpms. The motor must be rated for the proposed power, and size matters—take two 1,500 Kv motors, and the bigger motor (length times diameter) will comfortably turn a larger propeller, assuming both are of similar quality and efficiency. Some helpful vendors list the motors with both dimensions.

In a perfect world, all motors would be listed as Innov8tive Designs lists its Cobra motors. Here is an example of a Cobra C-4120/12 motor:

Cobra C-4120/12 Motor Specifications
Stator diameter: 41.0mm (1.614 inches)
Stator thickness: 20.0mm (0.787 inches)
Number of stator arms: 12
Number of magnet poles: 14
Motor wind: 12 Turn Delta
Motor Kv: 850 rpm/volt
No-load current (Io): 2.77 amps @ 14 volts
Motor resistance (Rm) per phase: 0.021 ohms
Motor resistance (Rm) phase to phase: 0.014 ohms
Maximum continuous current: 75 amps
Maximum continuous power on 3S LiPo: 830 watts
Maximum continuous power on 4S LiPo: 1,110 watts
Maximum continuous power on 5S LiPo: 1,390 watts
Weight: 293 grams (10.34 ounces)
Outside diameter: 49.8mm (1.961 inches)
Shaft diameter: 6.00mm (0.236 inches)
Body length: 51.8mm (2.039 inches)
Overall shaft length: 74.5mm (2.933 inches)

A Cobra motor and an ESC show designations.

This may appear to be more information than anyone needs, but it is perfect for someone wanting to know what the motor is and what it will do. The numbers in the name represent the dimensions of the stator and the motor wind (as a beginner, let the vendor help you with wind if you want more information).

The motor (stator) size is 41mm diameter and 20mm long, and the Kv is 850 rpm/volt. Another manufacturer might list this motor as “5052-850” because it uses the outside diameter of the motor instead of the stator size and lists the Kv rather than “wind.” That is why it’s important to know if a manufacturer’s numbers represent the outside dimensions or the stator.

Selecting Your Power System

This is why you read this far, isn’t it? Let’s use an example of a standard .40-size trainer-style airplane that weighs 51/4 pounds, uses a glow .40 engine, and spins an 11 x 6 propeller at approximately 11,000 rpm. Experienced glow pilots often look for a motor combination that will spin the same propeller at the same rpm and that works, but that’s not always the best way to do it. Electric motors are often more efficient when spinning larger diameter or deeper pitch propellers or a combination.

I created an example using an old trainer we have in the club from Hangar 9 called the Easy Fly 40. I removed the .40 glow engine and replaced it with a Cobra 4020/12 motor. Using a 4S 4,000 mAh pack, this will spin an 11 x 6 propeller at 10,700 rpm, similar to the old glow engine. The airplane will fly much as it did with the old glow engine, but by tweaking the propeller, I was able to make it fly much better.

The old glow engine was listed as producing 1 hp, which is the equivalent of 746 watts. With loss of efficiency, it’s likely approximately 3/4 hp or roughly 560 watts, which works out to 106 watts per pound.

The Cobra motor, with the same propeller, produces 488 watts or 93 watts per pound—barely a noticeable difference—and it flew well. The beauty of the electric was being able to experiment with propellers and come up with a 12 x 8 that produced 659 watts or 126 watts per pound and more thrust from the larger propeller. Thrust increased from 72 to 92 ounces, and that’s a huge jump in performance! Pitch speed also increased.

Guidelines for projecting power systems for electric airplanes are courtesy of Common Sense RC.

Keep It Simple

Keeping it simple is always the best way to go. In the previous example, I got into some efficiency factors, but I was working on the computer and letting it figure those. As a beginner, you can work with only the input numbers and still be satisfied with the results. Multiply your voltage (14.8 volts for our 4S example) by the projected amps.

The propeller will draw 56 amps (available from many manufacturers’ sites) and you’ll come up with 828.8 watts or 158 watts per pound for the 51/4-pound airplane. It’s higher than my computer-generated projection, but the computer figured several factors to project an 80% efficiency, which is the lower number and close to reality.

A MotoCalc screenshot of the input data screen (top) and results screen (bottom).

Tools

I primarily use two computer programs when I’m working up a new system that hasn’t been done before. ElectriCalc and MotoCalc will allow you to get as deep into the planning phase as you wish.

These programs do all of the math and have huge databases of motors, batteries, propellers, etc. to use. The help files alone are worth the purchase price and are constantly updated. Many vendors and manufacturers also have online drive calculators.

A screenshot of an ElectriCalc forecast of a project.

The Bottom Line

Select your airplane, decide what performance you want, and choose a motor system. Don’t like math? No problem! If your airplane is a 700-square-inch sport aircraft that will weigh 6 pounds and you want to do great aerobatics, try to find a system that the vendor says will produce 900 watts. That’s 150 watts per pound that will make you happy.

Try not to select a system that requires you to constantly run it at its maximum capacity and you’ll have a system that will last for years.

—Greg Gimlick
maelectrics@gimlick.com

Sources:

ElectriCalc
ecalc@slkelectronics.com
www.slkelectronics.com/ecalc

MotoCalc
info@motocalc.com
www.motocalc.com

Common Sense RC
(866) 405-8811
www.commonsenserc.com

“Getting Started in Electric Flight; An Introduction and Some BASICS”
http://theampeer.org/e-basics/e-basics.htm

RCGroups
www.rcgroups.com

Written by Jay Smith
As seen in the April 2018 issue of Model Aviation.

Written by Pat Tritle
Construct your own “homebuilt” biplane
Product Review
As seen in the April 2018 issue of Model Aviation.

Order Plans

Materials List

Wood

If a short kit is not used:
One 1/16 x 12 x 24-inch birch plywood
One 1/8 x 4 x 24-inch light plywood
Two 1/16 x 4 x 36-inch balsa
Three 3/32 x 4 x 36-inch balsa
Five 1/8 x 4 x 36-inch balsa
Two 3/16 x 4 x 36-inch balsa
Two 1/16-square-inch x 36-inch basswood
Twelve 1/16 x 3/16 x 36-inch balsa
Three 3/32-square-inch x 36-inch balsa
Eight 3/32 x 3/16 x 36-inch balsa
Two 3/32 x 1/4 x 36-inch balsa
Eight 1/8-square-inch x 36 balsa
One 1/8 x 1/4 x 36-inch basswood
Four 1/8 x 1/4 x 36-inch balsa
One 3/16-square-inch x 36-inch balsa
One 1/4-square-inch x 36-inch balsa
Four 1/4 x 1/2 x 36-inch balsa
One 1/4 x 36-inch balsa triangle stock
One 3/8 x 36-inch balsa triangle stock

Metal

.032 stainless steel safety wire
Two .032 x 36-inch piano wire
Two .093 x 36-inch piano wire
One .125 x 36-inch piano wire
Two 1/4 OD x 36-inch brass tube
Two 9/32 OD x 36-inch aluminum tube
One .015 x 1/4 x 12-inch brass strap

Miscellaneous

Two 1/8-inch wheel collars
Four 9-gram sub-micro servos
One Suppo 2820/6 1,000 Kv outrunner motor
One 30-amp ESC
One APC 12 x 6E propeller
Two 9-inch servo extensions
One 11-inch Y harness
CA hinge stock (Great Plains GPMQ3960)
One .032 inner-diameter x 24-inch plastic
tube (elevator pushrod tube)
One round toothpick (rudder control horn)
Heavy-duty nylon carpet thread (wing,
tail rigging, and rudder pull-pull cables)
Seventeen #2 x 3/8 sheet metal screws
Seventeen #2 flat washers
Four Du-Bro #158 landing gear straps
One .015 x 6 x 12 evergreen styrene sheet

Specifications

Wingspan: 54 inches
Length: 44 inches
Wing area: 930 square inches
Flying weight: 42 to 45 ounces
Power system: Suppo 2820/6 brushless outrunner; Suppo 30-amp ESC; APC 12 x 6E propeller
Battery: 2,000 mAh 2S LiPo
Radio system: JR XG8 transmitter; RG411B receiver; four Suppo SP-90 servos

The fuselage frame is completed with the addition of the aft top formers and stringers, bottom crosspieces, and tail skid mounting plate. The landing gear and tail skid are dry fitted onto the frame.

Product Review

The Staaken Z-1 Flitzer is a single-seat, open-cockpit, 1920s-style home-built biplane designed around the 65 hp Volkswagen engine. The Z-1, designed by Lynn Williams and produced by Flitzer Sportplanes of Aberdare, Wales, was supplied as plans for amateur construction, then in the late 1990s, was offered in kit form by Bell Aeromarine of Leicester in the United Kingdom.

The Flitzer is a relatively small airplane with an 18-foot wingspan and an overall length of 14 feet, 10 inches. Its empty weight is 481 pounds and it has a gross weight of 752 pounds. Its performance is impressive with a maximum speed of 93 mph, a cruise speed of 85 mph, and a stall speed at 42 mph, with a climb rate of 710 feet per minute.

A 1/4-Scale Park Flyer

The small Flitzer is a perfect candidate to launch a new concept: large-scale park flyers. I’ve built several 60-inch wingspan park flyers throughout the years with good success. The key to success is minimal weight and wing loading that allow for slow docile flight. The Flitzer, although a rather large model, was built with the wing loading at 6.5 ounces per square foot. At that weight, the model is capable of very slow flight and, with its agile flying qualities, is actually well suited for flying in medium to large parks. As a 1/4-scale model, it also qualifies for Big Bird meets.

The Flitzer is an all-wood design incorporating stick-and-tissue-style construction in the fuselage and tail group with egg-crate-style construction in the wings. As biplanes go, rigging the wings is easy. The design incorporates inverted V-style cabane struts and I-type interplane struts. The design also features plug-in wings that are retained by screws and removed in pairs.

Control is four-channel RC with a servo each for the rudder and elevator, and one for each aileron. Power is supplied by a Suppo 2820/6 outrunner motor with a 30-amp ESC, an APC 12-6E propeller, and a 2,000 mAh 2S LiPo battery.

Before construction begins, cut out all of the parts using the provided patterns. For those not into scratch-building, a laser-cut wood pack and vacuum-formed plastic cowl are available from Manzano Laser Works. Because the only commercially available wheels are far too heavy for the Flitzer, the 51/2-inch wheels are included with the laser-cut wood pack.

The 5.5-inch wheels are built up from 1/16-inch plywood with rubber tires. The wheel covers are cut from the plans and glued in place on the finished wheels.

Tail Section

Lay out the vertical and horizontal stabilizers directly on top of the plans, using the part numbers and wood sizes shown. When completed, lift the parts from the board and sand them to shape.

Cut the hinge slots in the locations shown. Make the hinges from CA hinge stock using the provided patterns, and dry fit them into the slots. Drill a #44 hole at the location shown on the rudder for the toothpick control horn and dry fit the horn in place.

Top Wing

If the laser-cut parts pack is used, assemble the A12/A12A main spar and A13/A13A rear spar over the detail drawings provided. Pin A6T in place on top of the plans. Align and glue A12 and A13 in place over A6T, using a couple of ribs to ensure proper spacing.

Fit all of the ribs in place on the spars and tack glue them in place. Align and glue the 1/4 x 1/2 balsa leading edge (LE) and 1/8 x 1/4 balsa trailing edge (TE) in place. Fit and glue the wingtips in place along with the 3/32-inch square balsa diagonal bracing. Laminate two A14’s together and glue in place.

Finally, fit and glue the 9/32-inch outside-diameter (OD) aluminum wing receiver tubes and 1/4 x 1/2-inch balsa rigging blocks in place. Remove the wing from the board and permanently glue all points of contact then sand to final shape. Repeat the process to build the other wing.

The top wing is egg-crate-style construction and is built directly on top of the plans for quick and easy assembly.

Bottom Wing

Assemble the A3/A3A main spar and A4/A4A rear spar over the detail drawings that are provided followed by the R3/R3A rib assembly. Pin SM1 in place on top of the plans. Dry fit all of the ribs onto the spars, pin in place over the plans, and tack glue all of the points of contact.

Align and glue the 1/4 x 1/2-inch balsa LE in place. Pin the 1/8 x 1/4 balsa TE in place, including the aileron, and glue at R1, R2, and R3. Fit and glue the wingtip in place followed by the 3/32-inch square balsa diagonal bracing. Align and glue A5 in place on A4 as shown.

Build the aileron while the wing assembly is still in place. Begin by sanding a bevel into AS using the R6 rib detail drawing for reference. Align and glue AR1 on AS and pin the assembly in place on top of the plans. Fit and glue all of the AR2 ribs in place, followed by the aileron tip. Finally, fit and glue A7 and the 1/16-inch-square bass wood diagonal bracing in place, flush with the bottom of the aileron.

Align and glue SM2, SM3, and A6B in place, and then fit and glue the 9/32-inch OD aluminum wing receiver tubes and 1/4 x 1/2-inch balsa rigging blocks in place. Remove the wing assembly from the board, cut the aileron free, and permanently glue all of the points of contact. Align and glue ASA in place on AS and sand to final shape. Finally, dry fit the aileron hinges in place. Repeat the process to build the other wing.

Fuselage Assembly

Begin by laying out the side frame directly on top of the plans, using the part numbers and wood sizes shown. Pin B1 in place then fit and glue all of the longerons and vertical and diagonal bracing in place. Align and glue PRG flush with the outside of the frame. Remove what will be the right-hand frame from the board and repeat the process to build the left-hand frame (except for the PRG).

The first step in joining the side frames is to align and glue FWR and FWL together. Align and glue CMF and CMFa onto Former 2. Laminate CMRa between two CMRs then laminate the two LGMa parts in place on the LGM. Make two sets. Pin the LGM assemblies in place on top of the fuselage framing plans and align and glue the side frames in place.

Use squaring blocks to ensure that they’re vertically aligned. Align and glue the Former 2 assembly and the rearmost Former 3 assembly in place. Align and glue the CMR assembly in place, followed by the CMR assembly and the front Former 3, Former 4, FWL/FWR, Former 1, and all of the bottom crossbracing ahead of Former 4.

Sand the bevel into the tail post using squaring blocks to ensure proper alignment. Pull the tail together and glue. Add all of the top formers and bottom crosspieces. Finally, glue all of the 1/8-square-inch balsa stringers in place.

Remove the frame from the board. Glue the tail skid mount assembly in place and sand the fuselage to shape. Assemble the tail skid and fit the shoe as shown and glue in place. Dry fit the skid into the mount.

Align and glue the two 9/32-inch OD aluminum bottom wing receiver tubes into the fuselage frame and add the wing retention tabs and support blocks. Make up the cockpit fairing using the provided pattern and glue it in place.

Wire Parts

Bend all of the wire parts to shape using the full-size patterns provided. Tape the front and rear landing gear struts in the mount beams and solder the axle in place. Wrap the joints with 24-gauge copper wire and solder again. Remove the landing gear and make up the front flying wire retainer hooks from .032-inch diameter stainless steel safety wire and solder in place.

Build up the top wing mount assembly by laminating CS1 and CS2s. Use the joiner tubes to ensure proper alignment. Fit the cabane struts into the fuselage, dry fit the wing mount onto the struts, and make any necessary adjustments.

Installing the Servos and Drive System

Set up the servo mounts in the fuselage as shown. Mount the rudder servo on center and the elevator servo on the right side. Run in the elevator pushrod guide tube and support it at the front, and each of the uprights using a pushrod stand-off and at the back at PRG. Dry fit the vertical tail and run in the pull-pull cables. Mark the location where they exit the fuselage on the plans. Align and glue the servos into the wings using silicone caulk. When dry, run the extension leads out through R1.

Build up the motor mount box and reinforce MM using 1/4-inch triangle stock. Mount the box on FW and reinforce it with 3/8-inch triangle stock.

I also hardened the wood with a coat of thinned epoxy resin on the inside and outside. Mount the motor, connect the ESC, and test run it to ensure proper direction of rotation.

Covering

Before covering begins, build up the interplane struts as shown. Fully assemble the model before covering. Test run all of the systems to ensure that everything fits and aligns properly, and that the power and control systems are all working correctly.

Because the goal is to keep the Flitzer lightweight, I recommend covering it with Coverite Microlite. Avoid the use of materials such as MonoKote or UltraKote because the excessive shrinkage will crush the somewhat lightweight structure.

Before covering begins, give the frames a final detail sanding to remove any remaining flaws. You can also scallop the formers between the stringers to provide a smoother cover job. After the frames are covered, apply the graphics as desired.

Final Assembly

Mount the landing gear and glue the tail skid in place. Glue all of the hinges in place then fit the bottom wing onto the joiner tubes. Using the wing for reference, align and glue the vertical and horizontal stabilizers in place. Fit the top wing panels onto the center section, dry fit the wing assembly onto the cabane and interplane struts, and check the alignment. When satisfied, glue the struts in place with 15-minute epoxy and allow the assembly to fully cure.

Vertical and horizontal stabilizer assemblies are built up then removed from on top of the plans and sanded to shape. The rudder and elevator have CA hinges.

Rig the wings and tail section using heavy-duty nylon carpet thread or bead wire. Drill .025-inch diameter holes in the struts and rigging blocks per the plans. The front flying wire is attached to the landing gear strut with the wire hook. Drill the vertical and horizontal stabilizers and add the rigging as shown. Both the front and rear bracing is done in one continuous loop.

Build the wheels per the plans and mount them using 1/8-inch wheel collars and add the 3/32 x 1/4-inch balsa landing gear fairings. Mount the cowl and add the desired dummy engine detail, windshield, cockpit combing, and any other details to suit.

The dummy Volkswagen engine cylinders were carved from balsa blocks and details were added using an aluminum dowel and electrical wire. The propeller was wood grained and detailed for a nice, scalelike appearance.

Build up and mount the battery tray as shown, followed by the battery hatch using the detail drawing provided. Balance the model at the point shown using the battery location to your best advantage. And finally, set up the control throws as shown and your model is ready to fly.

The battery hatch clips into the fuselage on the bottom. The bottom wings are retained by brass tabs and secured with #2 sheet metal screws.

Flying the Flitzer

The Flitzer is without a doubt the most honest and gentle biplane I’ve ever flown. The first flight was made using a 2,000 mAh 2S LiPo battery that provided a solid, scalelike performance. The model cruised nicely at half power with a comfortable reserve.

The takeoff was made into a gentle breeze with a shallow climb to altitude. To my surprise, no trim was required, and despite the massive ailerons, the Flitzer exhibited absolutely no adverse yaw. The model also turned equally well on rudder or ailerons alone.

With the controls set up as shown, and with the dual rates on, input was crisp and precise with no tendency to overcontrol. At the same time, the controls never felt mushy. The stall was a non-event, breaking right down the middle, and after the nose dropped, it immediately began to fly again.

Landing is easy, but because it’s a biplane, there is a need to carry some power on the approach. The approach is slow and gentle, with solid control response all the way to touchdown. I did shoot a few touch-and-gos and found that both three-point and wheel landings are equally effective.

I also tried using a 3S 2,200 LiPo battery, which provided more reserve power, but with the added power, it proved a little tricky finding a “happy” cruise power setting. The model was sensitive to changes in power as well. I wouldn’t call it “twitchy,” but it was not nearly as gentle a flier with the 3S battery. The choice of battery is best left to an individual pilot. And with that, the only thing left to do is enjoy the ride.

—Pat Tritle
patscustommodels@gmail.com

Sources:

Pat’s Custom Models
(505) 296-4511
patscustom-models.com

Manzano Laser Works
tomj@tularosa.net
www.manzanolaser.com

Callie Graphics
info@callie-graphics.com
www.callie-graphics.com

Hobby Linc
(888) 327-9673
www.hobbylinc.com

Micro Fastener
(800) 892-6917
www.microfasteners.com

AMA Plans Service
(800) 435-9262, ext. 507
www.modelaircraft.org/plans.aspx

Written by Greg Gimlick
A convenint and capable aerobatic helicopter
Product Review
As seen in the April 2018 issue of Model Aviation.

Bonus Video

Specifications

Model type: Electric RTF flybarless helicopter
Skill level: Intermediate to advanced
Main rotor diameter: 28.5 inches
Main rotor blade length: 12.8 inches
Head geometry: 120° (program as “normal”)
Head type: Collective pitch (CCPM) flybarless
Tail rotor diameter: 6.1 inches
Tail drive: Belt
Size: 450
Length: 34.3 inches
Height: 8.8 inches
Flying weight: 27.3 ounces
Power system: E-flite 440H 4,200 Kv brushless outrunner
ESC: Blade 45-amp with SBEC heli ESC
Flight battery: E-flite 11.1-volt 2,200 mAh 3S 30C LiPo
Flight duration: 4 to 6 minutes (depending on type of flying)
Price: $479.99
Radio (included): Spektrum DXe transmitter; Spektrum AR636A receiver; Spektrum H3050 sub-micro digital heli MG swash servos; Spektrum H3060 sub-micro digital heli MG tail servo

Pluses

• Fully assembled.
• Beautiful fiberglass canopy.
• Quality servos.
• Uses standard 3S 2,200 mAh battery pack.
• Carbon-fiber main blades.
• Telemetry-based text generator.
• Excellent, preprogrammed FBL system.

Minuses

• Bailout feature would have been nice.
• No DFC head.

The Blade 330X is an aerobatic-capable heli that will allow you to push your skills.

Product Review

I opened the Horizon Hobby Blade 330X RTF box and was struck by the aircraft’s gorgeous canopy. The fiberglass work and paint on this thing is gorgeous. I pulled it out and looked at the overall quality of the helicopter and I couldn’t wait to get started.

I’ve spent a lot of time lately flying micro and small helis, so suddenly the 330X (450 size) seemed like a return to my “big” machines.

The carbon-fiber blades are mounted and firmly secured with a foam keeper on the tailboom. I’ve gotten used to seeing direct flight control (DFC) heads lately, so it caught my eye that this employs the standard driven head control. No biggie, but it was a change from some recent Blade offerings. The other change is the Spektrum AR636A receiver that replaces the Spektrum AR7200BX that was used in some of the previous Blade designs.

Assembly

The 330X comes out of the box ready to fly, so there isn’t any assembly to be done. Put your battery on the charger so that by the time you’ve read the manual, it will be ready. My 330X is the RTF version that comes with a Spektrum DXe transmitter, but if you bought the BNF aircraft, you can use this time to program your radio.

The aircraft’s quality is outstanding and includes everything needed to fly. The colorful canopy stands out well on the bench or in the air.

I have a DX9 radio and set it up so that I could try both. The manual is the typical Blade offering that covers all of the programming requirements for the company’s various radios.

Programming notes: If you bought the RTF version with the DXe transmitter and you want to tweak any settings, you’ll need to get a transmitter/receiver USB Interface (SPMA3065) cable to connect to your laptop. There is also a transmitter/receiver programming cable called the Audio Interface (SPMA3081), if you’d rather do the programming through a smartphone app.

If you’re using an updated Spektrum transmitter capable of accepting telemetry-based text, you can tweak the proportional control device (PID) through that. These advanced settings should only be attempted by experienced people. The technical staff at Horizon Hobby suggest that you have at least 20 flights on the aircraft before attempting to adjust PIDs to allow everything to get broken in.

Take some time to look over the heli while your batteries are charging. This is a good time to familiarize yourself with the layout and look for any possible maintenance items that should be addressed before the first flight. Check the screws for security.

Look at the wiring to ensure that nothing can come in contact with the moving parts. I found that mine was extremely well done, with everything channeled beautifully and secured.

Neatness counts and Blade carefully routed all of the wires, antennas, etc. and secured them. You can see how accessible everything is if maintenance is required.

During your visual tour, you’ll also notice that this helicopter employs a driven tail that provides positive tail rotor control throughout the flight regime, including autorotations.

The belt-driven tail rotor is easy to maintain or adjust.

The flybarless (FBL) head is a standard-driven design and is set up perfectly upon arrival.

I removed the blades and checked them for balance, finding them to be good. While they were off, I attached a battery and checked all of the flight controls for proper movement. This also allowed me to confirm that my Hold function worked properly.

The 330X ESC utilizes a governor mode. If you’re new to governors, this is why the throttle curves might look different than what you’re used to. Be sure to program your radio to match the settings in the manual if you didn’t use the DXe that came with the RTF version.

Flying

Sooner or later you’ve got to quit looking things over and see what the 330X will do. I’m an intermediate pilot, but not a 3D monster, so for that end of things, I had my club mate, Daniel Lamb, wring it out. I was comfortable in Normal and Stunt Mode 1, but Stunt Mode 2 was sporty for me. I’ll stick with the first two modes for a while.

Daniel didn’t waste any time getting into Stunt Mode 2 and going full-blown 3D crazy! I loved watching my helicopter do things I wish I could do.

If you’re not comfortable flying a machine without a bailout feature, it might be prudent to have a more experienced pilot do the initial test flight. Nothing needed to be tweaked on mine and there were no surprises. For my flying style, I found all of the factory-set parameters to be more than sufficient.

For Daniel’s 3D work and his more finely tuned awareness of the feel of the machine, there were a couple of things he would have prefered tuned to his liking. What this heli provides is very solid initial programming that does everything quite well. If you are an advanced pilot, it provides a great base from which to begin tweaking.

There is more than enough power to do any maneuver you can think of and the tail held well throughout the routines. The climb is monstrously strong for the 65% governed motor. The stock E-flite 3S 2,200 mAh battery packs did a good job of keeping up with the demands. My flights go slightly longer because I’m not demanding as much from the battery as Daniel does while doing 3D, but duration for both is more than adequate.

I didn’t encounter any tail wag during my flights, but Daniel sensed a little with his higher demands on the system. After we get in a few more flights, we’ll dial those in slightly. By the way, if you go looking for the tail rotor gain settings, it’s under the gear section of your DXe programming.

One thing that stood out after flying my other helicopters that are this size is that the head speed is significantly lower. I like the lower head speeds that some of the newer helis are using. In Stunt Mode 2, the 65% throttle curve will give you approximately 2,000 rpm. During a couple of extreme maneuvers, Daniel felt that the motor was bogging slightly and he would like to dial this up a bit.

Whether the motor was bogging down or the batteries sagging remains to be determined. I think Daniel was slightly hesitant when he first checked out the heli to see if it would stand up to his maneuvers, but by the end of a few flights, he commented, “I think this will do anything you want it to.” The photos and video proved him right.

Daniel Lamb gets ready to do some 3D flying with the 330X.

Conclusion

If you’re looking to move up to a bigger heli from micros and minis, the Blade 330X RTF is a great step. This is a much updated version of the 450-class heli that Blade previously produced, and it’s clear that the company really put some thought into reintroducing this size to its lineup.

This isn’t a beginner’s helicopter, but if you’ve stepped up to a CCPM heli and you aren’t depending on flight stabilization technology to keep you in the air, it’s a logical next step. It runs smoothly, does all of the maneuvers, uses standard 3S LiPo battery packs, and hits a nice price point. I think it’s a winner!

—Greg Gimlick
maelectrics@gimlick.com

Manufacturer/Distributor:

Horizon Hobby
(800) 338-4639
www.horizonhobby.com

Blade
(877) 504-0233
www.bladehelis.com

SOURCES:

Spektrum
(800) 338-4639
www.spektrumrc.com

E-flite
(800) 338-4639
www.e-fliterc.com

Written by Josh Bernstein
Hone your 3D skills day or night
Product Review
As seen in the April 2018 issue of Model Aviation.

Bonus Video

Specifications

Model type: Electric 3D/aerobatic
Skill level: Intermediate to advanced pilots
Wingspan: 60.2 inches
Wing area: 792 square inches
Length: 58.2 inches
Wing loading: 18 ounces per square inch
Cube loading: 7.7
Weight: 99 ounces
Power system: Brushless electric outrunner
Radio: Spektrum DX6
Construction: EPO foam with carbon-fiber supports and plywood subframing
Price: $499.99; $449.99 without lights

Test-Model Details

Motor used: Potenza 60 3D 500 Kv brushless outrunner
Speed controller: Hobbywing Skywalker 80-amp ESC with HV 8-amp external SBEC
Battery: Glacier 6S 45C 4,000 mAh
Propeller: 16 x 6 custom-tooled Somenzini-Ribbe (SR)
Receiver: Two Spektrum DSM2 Satellite
Servos: Four Potenza DS33HV digital metal-gear servos
Ready-to-fly weight: 110 ounces
Flight duration: 5 to 12 minutes (depending on battery choice)

Pluses

• Lightweight, rigid, durable EPO foam with a plywood/carbon-fiber substructure.
• Wide flight envelope includes sport, precision, and 3D.
• Aura 8 Advanced Flight Control System provides stability and refinement.
• Couple-free, knife-edge flight out of the box.
• Simple assembly process—from unboxing to flying in roughly an hour.

Minus

• Trim changes must be made in conjunction with the Aura 8 flight control system, requiring a few extra steps during the initial flight.

With ample power and stability, the QQ CAP’s hovering mannerisms inspire confidence.

Product Review

Go to any online RC forum and search for CAP 232 and you’ll be inundated with threads discussing this iconic airplane. Loved by many, this low-wing, aerobatic airplane was scaled from the CAP series of aerobatic aircraft, which dates back to Claude Piel’s CP.30 Emeraude in the early 1960s (eventually becoming the full-scale Mudry CAP 230/231/232).

As airframes go, the CAP 232 has always been thought of as more of a “scale aerobatic” platform. With the increased availability of a midwing, pure 3D machine, the CAP airframe has fallen out of favor with some aerobatic fliers. The wing and stabilizer placement on a CAP can result in some unique flight characteristics, although many of these issues can be mitigated during setup. As any CAP enthusiast will tell you, proper setup on a CAP is mandatory.

For Flex Innovations to choose to release a 3D CAP model in the current climate shows an impressive level of confidence. Considering that Quique Somenzini (QQ) is part of Flex Innovations, that confidence is well founded.

Flex Innovations has an impressive team of industry veterans, a great reputation, and a solid fan base. I am impressed with the company’s ability to take such an iconic airframe and make it perform so well. Tweaking and reengineering an old-school design then marrying it to modern technology results in a CAP 232EX with almost none of the challenges present in the original design.

Flex Innovations considers the QQ CAP as the perfect next step after its QQ Extra 300 and Mamba 10 aerobatic airplanes. With a wingspan slightly more than 60 inches, a length of 58.2 inches, and weighing nearly 7 pounds, this is not your everyday foamie. With nearly 800 square inches of wing area, it is big for the 60-inch class of aerobats, yet it’s easily broken down and transported with the wings off. Plus, adding a few extra 6S 3,500 LiPo battery packs won’t break the bank.

Although the build process is straightforward, I have listed a few points online and in the digital edition that deserve extra attention.

Foam models sold as Plug-N-Play (PNP) often include subpar components. Although considered a cost-savings technique, many decent airframes have been brought low by an undersized or poor-quality motor, ESC, and/or servo set. Flex Innovations’ design team has turned this paradigm on its head. The QQ CAP 232EX comes equipped with solid components.

The QQ CAP arrives with its components installed and the control surfaces prehinged, allowing the pilot to go from unboxing to flying in roughly an hour.

A Potenza 60 3D motor is mated to a Hobbywing SkyWalker 80-amp ESC with an external 8-amp switch-mode battery eliminator circuit (SBEC). This provides plenty of power to the Potenza digital/metal-geared/high-voltage (HV) servos.

Including the HV servos and an external SBEC shows how seriously the company takes its customers’ needs. The HV servos provide extra torque and speed, and the external SBEC allows pilots to maintain control over the airplane should the ESC fail. Generally, both are only found on higher-end models.

Combining digital/metal-geared/HV servos with bilateral ball links results in fast and powerful control-surface deflections with minimal slop.

Construction

The airplane arrived tightly packed, with each part separated and supported. The QQ CAP 232EX is sold only in a Super PNP configuration with either a blue or yellow scheme. The manual suggests a 1-hour build time.

For those who prefer to fly in the early mornings, heavy fog, or late evenings, a Night version is available with an array of LED lights built into the airframe. The lights can be powered from the main 6S battery pack (using the included balance lead) or from a small 3S battery pack. Although this review covers the Night version, the build process and programming steps for the Standard version are identical.

The optional Night version has LED lights running throughout the airframe, allowing for nighttime and early morning flying.

The manual provides clear instructions on programming your transmitter and walks you through the Aura 8 AFCS setup. According to Flex Innovations, the Aura 8 is compatible with “virtually every receiver on the market today.” I opted to take advantage of this flexibility by utilizing a pair of simple Spektrum DSM2 satellite receivers (full-range receivers without ports).

The Aura 8 AFCS is compatible with a number of radio systems. It is preloaded with all of the necessary programming, simplifying radio setup

Having eight channel ports (and advanced programming and mixing capabilities), the Aura 8 can manage all of your servo connections, allowing a satellite receiver’s digital connector and a six-channel radio to control the system.

A major selling point of the QQ CAP 232EX is the fact that all programming is done at the factory, requiring minimal radio setup. With all of the rates and exponential settings, coupling mixes, stabilization gains, and flight modes preset in the Aura 8, after you’ve installed your receiver you can get right to flying.

Using a PC-based computer or tablet and the supplied USB cable, the Aura 8 allows users to customize a wide range of parameters. Although customization is nearly limitless, most users will choose between the Stock and the Expert flight mode setups. Each flight mode includes a specific combination of rate, exponential, and stabilization gain.

Particularly for a more skilled 3D pilot, it is well worth the small amount of effort required to select the Expert flight mode setup. Having spent countless hours flying my Flex Innovations Mamba 10 biplane, which utilizes a similar flight mode setup, I can speak to the benefit of having a low- and high-speed 3D mode.

The two 3D modes have distinct rate and stabilization gain settings that maximize the different styles of 3D flight. Post-stall maneuvers (harriers and hovers) feel more stable and locked-in, and high-energy tumbling maneuvers, which often require high-speed entries, are maximized. Switching to the Expert flight mode setup should be done after all linkages are connected. Being able to turn the stabilization off (stock flight mode 1) is useful during assembly.

Regarding the Aura 8, some traditional pilots, accustomed to having near dictator-level control over their model’s setup and radio programming, might be turned off by these advanced stabilization systems. However, with more manufacturers releasing models that utilize programmable stabilization, and with the benefits such systems can bring, I think it’s good to develop some comfort with the available technologies.

The QQ CAP 232EX is an advanced 3D/aerobatic airplane. It is marketed toward intermediate and advanced pilots who are looking to improve their skills. (After performing a “Quick-Trim” process following the maiden flight, no additional programming changes were required. All rates, exponential settings, and coupling mixes were spot-on.)

The manual recommends balancing the model fully loaded, under the wing in an upright orientation that is 105mm aft of the rearmost side of the landing gear slot. The generous battery tray allows for some adjustment depending upon the battery size, and I found that I was able to achieve this initial center of gravity (CG) with a range of LiPo battery packs.

The battery tray is generous, but the removable canopy is massive. After it is removed, there is total access, easing assembly, battery switches, and receiver setup.

The generous battery tray allows easy access for a range of battery packs, providing flight times from 5 to 12 minutes.

I like to bench-test aircraft to confirm that the power system is working correctly, determine the model’s power-to-weight ratio, and test the battery packs to be used during flight testing. With a reasonably new Glacier 6S 4,000 mAh 45C LiPo battery pack, the motor pulled 60 amps, or slightly less than 1,400 watts, resulting in approximately 200 watts per pound.

On 3D models, power is nice, but thrust is king. With the low-pitch, custom-tooled propeller humming at full throttle, I could barely keep the model from turning my living room into its maiden flying site.

Flying

After range-testing, servo deflection checks, and confirming the CG and propeller tightness, I selected Expert Flight Mode 1 (sport/precision) and taxied the QQ CAP to the runway. I brought power up to roughly half and rotated the airplane off of the runway in a scalelike manner. Leveling off and reducing throttle to half, I began my standard in-flight testing by trimming the airplane to fly straight and level upright.

Most stabilization systems require you to reset the trims to neutral and mechanically adjust your control surfaces after trimming. This avoids a trim-shift issue when switching flight modes. The Aura 8 has a Quick-Trim feature that allows users to handle this process electronically, negating the need to disconnect and adjust multiple linkages.

With trimming complete, I rolled the airplane inverted to get a sense of its CG. With my 590-gram, 4,000 mAh 6S battery pack centered between the two battery straps, the QQ CAP required only a breath of pressure on the elevator stick to maintain level, inverted flight. Slightly nose-heavy is the sweet spot for 3D/aerobatic flight, resulting in a good balance of 3D, precision, and balloon-free landings.

I spent a few minutes flying gentle sport patterns, both upright and inverted, with an occasional stall turn or Immelmann. The model performed these mild-mannered maneuvers beautifully, but it felt like driving a Porsche in stop-and-go traffic.

I rolled the model into a knife-edge orientation with virtually no coupling present, and the QQ CAP tracked straight and true.

I spent the next minute or so flying knife-edge ovals and Figure Eights, impressed with how locked-in the model felt, whether at speed or moving slowly in a high angle-of-attack. Snaps and rolls were crisp and precise. I was able to perform clean point rolls and slow rolls to my heart’s content.

Eager to see what this 3D machine was capable of, I lined up on the runway, reduced throttle, and slid the model in for a scale landing. There is no need to discuss this airplane’s landing mannerisms. Fly it in at 1/4 throttle and it’s ridiculously docile.

Flex Innovations suggests a range of 5- to 12-minute flight times, depending on the battery size. I experimented with different batteries and found this to be true.

Starting with a fresh battery pack, I selected Flight Mode 2 (high-speed 3D mode) and launched the QQ CAP skyward with a full-throttle takeoff. Tremendous vertical performance had the model 100 feet high in seconds. I reduced power and floated the model down in a flat spin for some post-stall testing.

The CAP airframe is considered to be stable during inverted harriers because the tail surfaces hang down in clean, undisturbed airflow. On the other hand, upright harriers (with its wing set lower on the fuselage) have historically been a dicey proposition. Again, the design team at Flex Innovations has sprinkled its magic dust. The QQ CAP is as stable in harriers as any airplane that I’ve flown.

Regarding the QQ CAP’s hovering characteristics, I’m at a loss for superlatives. It is truly remarkable. With more than enough power to blast out of danger and with such well-mannered composure and stability, the model seems content to simply hang nose-high a few feet off the ground for as long as you’d like.

After temporarily getting my fill of post-stall testing, I landed the QQ CAP, switched out batteries, and again selected Flight Mode 2. Bringing the model off the ground with speed, I entered the flying field with full throttle and performed one of my favorite maneuvers: the pop-top.

Combining power, energy, and a hint of gracefulness, the pop-top is a good maneuver to test multiple aspects of an aerobatic model’s mannerisms. The QQ CAP didn’t disappoint, and I continued aggressive testing with a range of violent tumbles, culminating in the wildly popular knife-edge spin.

The Aura 8’s factory settings (and recent firmware upgrades) result in the system providing a near-perfect balance of assistance, without interfering during more advanced maneuvers.

The LED lighting system brings a whole new aspect to flying. The lights are bright enough that complete darkness isn’t necessary to experience the effect. Early morning fog provides a great atmosphere to utilize the feature, and there were several mornings with the QQ CAP where fog kept all other airplanes grounded.

Of course, there’s nothing like flying the QQ CAP 232EX Night version at night. With LED strips running the length of the fuselage and throughout both the wing and stabilizer, the entire airframe is illuminated.

A well-designed 3D/aerobatic model should have a flight envelope that covers the three fundamental cornerstones of 3D/aerobatic flight: precision, post-stall, and extreme aerobatics. I’ve flown airplanes that are incredibly precise and tumble like mad, but when I bring them in for some low-and-slow fun, they are annoyingly unstable. I’ve flown airplanes that are great tumblers and a joy to harrier, but coupling is terrible and precision tracking is horrid.

Although I might occasionally bring such an airplane to the field, it will never be my go-to aircraft. The QQ CAP 232EX provides solid performance in each area. Additionally, based in no small part on its massive wing area, this model can feel downright floaty.

Features:

Highly engineered and designed, the model includes several features of note:

“Shark’s tooth” vortex generators at the wings’ leading edges reenergize the airflow, improving slow-speed control and reducing tip stalls.

The Aura 8 Advanced Flight Control System (AFCS) manages flight modes, mixes out coupling, decreases wing rock, and can be mated to a simple satellite receiver for full-range flying with a six-channel radio. Firmware updates allow for increased stabilization while reducing “bounce-back” effect.

A plywood substructure and carbon-fiber wing and fuselage supports, increase rigidity while keeping weight in check.

Massive prehinged control surfaces, combined with moderate wing loading and ample power, offers true 3D capability.

Four fast and powerful, preinstalled, high-voltage, digital metal-geared servos require no linkage assembly.

Ball links utilized at both servo and control horn for slop-free operation.

Capable of flying with battery packs ranging from 5S 2,800 mAh to 6S 5,200 mAh.

The stylized sticker package is a welcome substitute for paint options found on many foam models.

Instead of an all-inclusive bag of parts, specifically labeled bags contain only the parts needed for each step, simplifying and speeding the build process.

Maintaining its iconic shape, the Flex Innovations QQ CAP pays homage to history, while embracing technical innovation and progress.

The Build Process

Although the build process is straightforward, a few points deserve extra attention:

Before installing the rudder and elevator linkages, confirm that the servo arms are perpendicular to the servo cases. Do this by turning on your radio, switching your CH5 (gear) to the Mode 1 (gyro off) position, and power on the model. (Wiggle the airframe to confirm no stabilization.) The servo arms and linkages (except at the elevator control horn) can now be installed.

The rudder is prehinged at the factory to a small section of the vertical fin, which is attached to a corresponding section of the fin with medium CA glue or epoxy. A lower, plastic hinge piece is mounted to the fuselage with a self-tapping screw. This screw shouldn’t be tightened completely because some play is necessary for bind-free hinge movement.

When a model is shipped with CA hinges preinstalled in foam, it’s a good idea to tug on all of the control surfaces to confirm proper retention. I found two places where some additional CA adhesive was necessary. I fully deflected the surface and dripped some thin CA on the hinges.

When installing the stabilizer/elevator halves, be patient and gentle. The halves slide into tight plastic receivers. This is a good because rigid tail section benefits flight performance, but forcing the fit during assembly could result in damaging your new airplane.

The Stock Setup and Expert Setup

Stock Setup:

• Flight Mode 1: Gyro off. Sport/precision rates, low exponential.
• Flight Mode 2: Sport mode. Sport/precision rates, low exponential, low gains.
• Flight Mode 3: 3D mode. High rates, moderate expo, high gains.

Expert Setup:

• Flight Mode 1: Sport mode. Sport/precision rates, low exponential, low gains.
• Flight Mode 2: High-speed, 3D mode. “For half to full throttle … ideal for tumbling and high-energy aerobatics.” Rates and exponential are high, low gains.
• Flight Mode 3: Low-speed 3D mode. “Ideal for harriers, hovering, and other slow speed flight.” Rates are maximized and exponential is high. Highest gains. (“As the gains are at their highest, control surface oscillation may occur at high speeds which may lead to a potential crash.”)

Conclusion

Smooth and stable when I wanted it to be, aggressive and violent when I wanted it to be, precise and crisp … Well, you get the point. It usually takes me a dozen or so flights to fall in love with an airplane, but after just a few flights with the QQ CAP 232EX, I was on my knees proposing. This model represents a blend of a well-engineered airframe capable of extreme 3D performance with an advanced flight control system that smooths any rough edges. It provides a comfortable flight experience, and does so with a light touch to allow the pilot to maintain a feeling of direct connection with the airplane. Considering its aesthetic appeal, power, precision, stability, tumbling abilities, durability, and general width of flight envelope, the QQ CAP 232EX is a game changer.

—Josh Bernstein
joshbernstein2@yahoo.com

Manufacturer/Distributor:

Flex Innovations/Premier Aircraft
(866) 310-3539
www.flexinnovations.com

Sources:

Spektrum
(800) 338-4639
www.horizonhobby.com

Potenza
(866) 310-3539
www.flexinnovations.com

Written by George Kaplan
A versatile and enjoyable sport aircraft
Product Review
As seen in the April 2018 issue of Model Aviation.

Bonus Video

Specifications

Model type: Sport scale ARF
Skill level: Intermediate to advanced pilots
Wingspan: 71 inches
Wing area: 550 square inches
Airfoil: Flat bottomed
Length: 47 inches
Weight: 5-3/8 pounds; 6 pounds with updated CG
Power system: Preinstalled brushless outrunner motor and 40-amp ESC; 4S 2,200-3,000 mAh LiPo battery required
Radio: Servos come preinstalled; radio and receiver required; if used for glider towing, optional servo needs installed
Price: $329.99

Pluses

• This PNP kit includes the motor, ESC, and servos.
• Carbon-fiber wing joiner.
• Quick wing-release mechanism with a positive snap locks wing in place.
• Two magnetic hatches give quick access to the receiver and LiPo battery compartments.
• Three multicolor scale sticker schemes included.
• Preinstalled LED lights for navigation, landing, and strobe.
• Includes standard wheels and larger foam tundra tires for rougher fields.
• Optional float and ski sets give the Husky 1800 the ability to operate virtually anywhere.

Minus

• The Husky is tail-heavy using the 82 mm CG placement stated in the manual. Moving the CG forward to 70 mm improves flight performance.

Outfit the Husky with the optional ski kit and you can take off from snow, sand, and even thick grass. The skis bolt right onto the main gear.

Product Review

The full-scale Aviat Husky is a tandem, two-seat, high-wing light utility aircraft built by Aviat Aircraft in Wyoming. It entered production in the mid-1980s and has received many power and performance updates. Its great flying characteristics and large load-carrying ability make it popular with commercial and private pilots.

Graupner USA has come out with an RC version of the Husky 1800. The company states that the model has the same Short Takeoff & Landing (STOL) capability as the full-scale aircraft and captures its scale looks.

Graupner not only provided its Husky kit for this review, but also sent along optional float and ski kits. Being one who has always been interested in graphic arts and design work, what struck me first was the printing on the outside of each of the three boxes. A typical kit has a simple label slapped on a plain box, or maybe the top of the box has printing. Graupner’s boxes have nice artwork covering all six sides of the boxes.

They are great to look at and informative. In the case of the optional skis and float kit boxes, the assembly and mounting instructions are on the back of the box. All of the parts arrived in great shape thanks to the abundance of foam protection, polybagging, and wrapping of the airframe components.

The Husky 1800’s airframe is mostly made of what Graupner refers to as SOLIDPOR. It is similar to EPP foam, but more rigid, and provides a nice, smooth finish and feel to all of the surfaces.

Inside the “hard points” of the airframe are many parts made from injection-molded plastic. This same plastic is used for some of the Husky’s parts, such as its wheel pants. I was struck by the quality of the plastic and the molding.

With this being a Plug-N-Play (PNP) model, much of the work is completed at the factory. This includes the small stuff such as preinstalled carbon-fiber reinforcing, hinging and attaching the control hardware, installing the pushrods, etc. Many other tasks, including servo installation, attaching the wing struts, the motor and ESC installation, and installing the navigation lighting system also come completed.

One thing that’s not done at the factory is applying the stickers, giving the pilot the option to finish the model to match his or her taste. Huge pressure-sensitive sticker sets are provided in scalelike red, yellow, or blue schemes.

Rounding out the contents are two types of landing gear (conventional with wheel pants and larger tundra tires), a spinner and propeller, four lengths of carbon-fiber rod, and a multilingual instruction manual.

These large foam tundra tires are included with the Husky kit. You can switch from the regular tires and wheel pants to these in roughly 5 minutes, and everything bolts in place.

There aren’t many parts needed to finish the Husky’s assembly. To go from this point to flight ready takes slightly less than an hour, although decorating it with the included sticker sets will increase that time.

Assembly

There wasn’t much for me to do to assemble the airframe. Everything can be done in a few hours—most of which is spent applying the stickers. You can see the steps by downloading a copy of the manual from the Graupner USA website.

Although the first step in the manual is installing the main gear, I recommend first applying the stickers before everything is assembled. The stickers are pressure sensitive and die-cut, preventing wear and tear on your scissors.

For the most part, the decals line up as they should, but there were gaps around the edge of the vertical fin and the top of the fuselage. I cut and pieced together some of the leftover matching sticker “bleed” area to help fill in the gaps. It didn’t look great up close, but it helped hide the seams when viewed from a few feet away.

After the stickers were applied, the steel main gear was attached to the fuselage. It’s quite sturdy and includes a couple of tension springs to help support it.

Now you can choose which type of landing gear to use for your initial flight. The conventional gear includes a pair of 31/2-inch foam tires, a set of axles, and wheel pants that have two halves that bolt together. Another option is the larger 41/4-inch tundra tires that are wider and have their own separate axles.

Work now shifts to the rear of the fuselage where the tail surfaces and tail wheel assembly are bolted into place. After attaching the pushrods to the control horns to the elevator and rudder, four pieces of carbon-fiber rod are glued in place to add support to the tail surfaces. Although the manual doesn’t suggest it, I chose to use foam-safe CA adhesive on the foam model, to be safe.

At this point, all that’s left to do is some radio installation work. The Husky 1800 comes with preinstalled servos, but the servo extensions need to be properly positioned. Included are the servo extensions for the aileron and flap servos, as well as the navigation lights. The ends of these extensions are glued into the pockets, which are molded into the left and right root joint of the wing. Mark the connectors to help you assemble the Husky at your flying field!

To complete the Husky, add the receiver of your choice and power it up for the first time. (Don’t install the spinner and propeller until you have properly set up the Husky. Safety first!)

This small hatch on the fuselage’s port side gives you access to the receiver compartment. If you choose to use the Husky as a towplane, you can also mount the tow-release servo in this area.

You might notice that I’ve only focused on the fuselage until now. That’s because the wing halves are ready to go right out of the box, except for attaching the stickers. Each wing half incorporates an aileron and flap servo. The control linkages and surface hinging come preinstalled. Even the wing struts and jury struts are ready to go.

The red and green LED navigation lights on each wingtip and strobe lights on the wing plug into the LED controller located in the fuselage.

A unique attachment mechanism locks the wing halves into the fuselage. Each half has a small, hinged lock that securely snaps the wing into place. While it’s locking, it is also drawing the wing into the fuselage for a snug fit. There is a finger hole molded into each lock so that you can unsnap it and remove the wing panel.

No screws are necessary to attach the wing. These built-in locks snap each wing half in place and draw them tight to the fuselage.

With everything in place and using the recommended battery, the Husky balanced where the manual recommended (82 mm). The total weight, including the battery, was 53/8 pounds.

Flying

When it came time for the Husky 1800’s maiden flight, I packed up everything and headed to a large grass field that is used for high school football practice.

Pointing it into the wind, the Husky was off the ground quickly (in approximately 5 feet), as advertised. I expected it to be a docile, smooth-flying model, but while doing the mandatory photo passes, I wasn’t comfortable with it. If I was flying slow and steady, the Husky flew as expected, but in the turns and when throttled up, it was all over the place.

I first thought that it was tail-heavy, but I wasn’t sure. A few flights later, I still hadn’t figured things out. I could have activated the built-in stability of the Falcon 12 receiver, but that would only mask the problem.

I headed home and after tinkering with the model and searching the internet, I stumbled upon a thread where someone was also having a similar problem. That person found that moving the center of gravity (CG) forward solved the problem, so I tried it.

Moving the CG forward from the recommended 82 mm to roughly 70 mm dramatically improved the Husky’s flight characteristics. Moving the CG required adding a fair amount of nose weight. Instead of adding a lump of dead weight, I slipped in another 2,400 mAh battery—one on top of the other. It’s a snug fit, but required no trimming for the brand of battery that I was using. I also rewired the battery connection so that I could use both batteries at the same time, in parallel, for longer flight times.

It was a night and day difference flying the Husky with the new forward CG location. There was no more dropping off in the turns, no more crazy pitch changes when changing the throttle, and better still, no more super-sensitive elevator!

The Husky requires some aileron-rudder coordination in the turns. It’s easy to turn the aircraft using the rudder with a touch of up-elevator to hold altitude.

Its flat-bottom wing doesn’t lend itself well to aerobatics, but you can coax aileron rolls out of the Husky. Loops, lazy eights, and hammerheads are more the Husky’s forte. There’s plenty of power to pull it through most of these maneuvers, but it’s not a 3D machine, nor should it be.

For a flat-bottom airfoil design, after it’s inverted, it flies well, requiring less down-elevator to keep it level. Snaps and spins under power are tight and have a quick rotation, but if they are performed with the power off, they are slow and more like a barrel roll.

I set the flaps on the Husky on a three-position switch (none, half 35°, and full 70°). Using the flaps, the Husky can get off of (and onto) small runways because it can fly at ridiculously slow speeds while still remaining controllable.

One other thing I haven’t really touched on is the Husky 1800’s preinstalled LED light system. Although noticeable during the day (if you point the lights out), they are best viewed during early morning or late evening flights, or even at night—giving the Husky an extra bit of scale realism.

Accessorizing the Husky

As shipped, the Graupner Husky 1800 is capable of taking off from pavement, grass, rough fields, and even dirt. As if the included standard wheels and tundra tires weren’t enough, Graupner has two other options.

The first is a ski set. Included in this add-on are skis that attach to the main wheels and a smaller ski that attaches to the tail wheel.

Each of the skis bolt into place and include a set of springs that hold them at the correct angle and provide some shock absorption. In a matter of a few minutes, you can outfit the Husky to tackle snow.

If water is more your thing, an optional float set is available. Some assembly is required, but when finished, it is a sturdy setup with twin floats and steerable rudders on the back of each float.

A string is attached to each rudder and to a modification on the tail wheel assembly. It works, but it’s finicky to get right. Each float has the option for a servo to be installed and attached to the preinstalled pushrods. You then will have to run extensions from the servo up the float struts and into the fuselage. (Servos and extensions are not included in the float package.) Regardless of the surface you want to fly from (or land on), it appears that Graupner has you covered.

There’s one more thing. The Husky has the capability to be converted into a towplane for gliders. By installing your own servo in the fuselage, it can be attached to the preinstalled tow hookup on top of the fuselage and allow you to tow sailplanes with up to a 2-meter wingspan.

This optional float kit adds to the Graupner Husky 1800’s versatility. The foam floats are supported by a metal structure and can quickly be attached or removed from the fuselage.

In Conclusion

It’s hard to describe the tremendous amount of thought that clearly went into this Graupner Husky 1800 kit. The company did a great job of capturing the look of the full-scale Aviat Husky.

Everything fits well and all of the molding is first class. The mechanism used to “snap” the wing halves to the fuselage works well and holds each half firmly in place, even during aerobatic flights.

After the CG location is corrected and the aircraft is flown as intended, the Husky 1800 makes a great STOL model, especially when its flaps are extended. Depending on the throttle setting, it can slowly fly in small parks and ball fields or take up a lot of sky at a club field with more throttle.

An average flight with the 2,400 mAh LiPo battery lasts 8 to 10 minutes. Going up to a larger battery (4,000 mAh or higher) can allow you to fly for roughly 15 minutes.

The Husky is capable of STOL landings and takeoffs. To perform those well, you need flaps. This shows the Husky’s large flaps halfway deployed on this slow flyby.

—George Kaplan
flyingkaplan@yahoo.com

Manufacturer/Distributor:

Graupner USA
(855) 572-4746
www.graupnerusa.com

Sources:

Kinexsis LiPo battery
(800) 338-4639
www.horizonhobby.com

Written by Chris Mulcahy
RC Helicopters
Column
As seen in the August 2014 issue of Model Aviation.

For this month’s column, I talked with Team Futaba pilot, the king of low head speed and old-school 3-D, Gary Wright, about flybarless gyros. I want to thank Gary for taking the time to share his knowledge with MA.

Team Futaba pilot Gary Wright explains the ins and outs of flybarless gyros.

Chris Mulcahy: What is a flybar?

Gary Wright: A flybar is a device whose purpose is to create unsolvable vibrations and make helicopter flying as difficult as possible. Seriously, a flybar is a type of mechanical rate gyro, whose purpose is to enhance stability and controllability of a helicopter.

It is a spinning bar that wants to fly in the same plane all the time, thus giving us a crude reference point. It generally connects to the blade grips in such a way that it imparts a pitch change in the blades in an attempt to restore stable flight due to its gyroscopic reference plane.

There are two common types of control for a model helicopter. I’ll simply refer to them as Bell and Hiller because we’ve [likely] all heard the term “Bell-Hiller mixing arm” on flybar-equipped helis, so the terms are familiar.

In a “Bell” control system, input from the swashplate is transferred directly to the blade (like our modern flybarless helicopters). In a “Hiller” system, control is transferred to the flybar and not directly to the blades. The flybar, in turn, controls the blade pitch.

Bell-type systems exhibit great initial responsiveness, but the control response tends to decay as the helicopter accelerates about an axis. This is because the initial angle of attack increases with a cyclic pitch input, but the angle of attack decays as the helicopter starts rotating about that axis. Hiller-type systems lag a bit in initial response, but they exhibit more consistency in rate … [in other words] they’re a bit slow to get started but are good at maintaining a given rate of rotation once accomplished.

Because of the input to the aerodynamic devices (commonly paddles on our flybars, but can be cup, ring, or other shapes), they tend to force the flybar (our mechanical gyro) into a new plane of rotation in relation to the blades, thus assisting in maintaining rate of rotation.

As you’ll see on most models with a flybar, there is a mixer arm that allows input both directly from the swashplate and from the flybar—“Bell-Hiller mixing arm.” This results in a somewhat crude approximation of a PID [proportional integral derivative] control loop.

CM: Now that we know what a flybar does, can you explain what a flybarless gyro does?

GW: A flybarless gyro does the same thing as the flybar, hence the terms virtual, or electronic, flybar. The reference, however, is an electronic sensor rather than the mechanical sensor we had with the flybar, plus integration of a more advanced control loop, commonly a PID loop (I don’t know of a flybarless gyro that doesn’t use PID, but there could of course be some that use other control algorithms).

The flybarless gyro gives us somewhat of a closed loop system rather than an open loop system, thus control and stability can be more precise. To expound a bit, an open loop system would be like an automobile cruise control, consisting only of a throttle lock. On level ground, it would be somewhat acceptable. However, it would accelerate downhill and accelerate uphill because there is no reference from which to compare and the control loop is “open.”

The cruise controls we have today are closed loop systems. They have a reference (a sensor) that feeds back information about the speed that is being experienced and can adjust the throttle position to maintain that speed via some algorithm (a P/I-type system to maintain consistency of rate). Flybarless gyros give us this type of capability, but with far faster responsiveness than a mechanical flybar.

Nearly all flybarless gyros can be tuned in some way. This Futaba CGY750 can be programmed right on the gyro.

CM: There are plenty of gain settings to get a grip with. What exactly is PID, and how does it affect our helis?

GW: PID is an acronym for proportional integral derivative. It is an equation for a closed-loop control system that is elegant and can result in not only stability, but consistency in control rates, and tuning ability of acceleration/deceleration rates. In our control loops the gyro sensors sense a rate of rotation.

Compare it to the rate being commanded by the pilot, then compute an error if those rates are different, and command movement of the servos based on that error. If all they did was sense a motion and feed in an amount of correction, they would be “P” control loops—rate gyros—and would simply damp (no, not dampen—they’re not getting wet) unwanted movements.

With the PID algorithm they compare the experienced rate with the commanded rate, and compute the amount of correction; however, they are also comparing the rate to many iterations of sampling over time and integrating that information in the computations to attempt to maintain consistency, and they are also utilizing the derivative to predict the future needs, thus assisting in applying a more exact correction.

If you study the PID algorithm, (it won’t be difficult to find on the Internet), you’ll see how it utilizes the three gains: proportional, to know the amplitude of corrective action that’s needed; integral, to maintain consistency of rate over time; and derivative, to refine the stops.

Simply stated, if it’s not stable, your P gain may be wrong. If it’s not consistent, like a tail whipping when doing pirouettes in forward flight, your I gain is not right. If it bounces or rebounds on stops, or doesn’t stop precisely, your D gain is probably incorrect.

When the proportions of I and D are correct, you can just adjust the proportional gain (the “normal” gyro gain we’ve been familiar with for years), because it controls the overall amount of correction and although each one can interact with the others, just think of the proportional gain as the master.

CM: What is your typical procedure for setting up a new flybarless heli?

GW: I tend to like to use a system or procedure to adjust something rather than the “hunt-and-peck” method of experimentation. I’ve developed a system by which I can set up any flybarless controller rather quickly, as long as I can determine what naming convention they use for each of the functions.

For instance, all have P, I, and D gains; however, they may refer to them as stability, consistency, response, P, I, D, “Bell and Hiller,” etc. It can be confusing as they don’t all use the PID standard for naming.

Plug everything in correctly, and if using a type of single input (for example, SBus for Futaba), ensure your channel mappings are correct. Aileron input for the transmitter must be aileron input on the device, for example.

Check that all the “wiggly bits” wiggle in the correct direction. Most of our machines use three servos for the swashplate, so there are three inputs and two selections for each: forward and reverse on the servos, so three to the second power means there are only nine combinations.

I simplify it by checking one servo with collective pitch, reverse if needed, then the second servo, then the third. When collective works correctly, I simply reverse aileron or elevator in the transmitter if needed.

Select normal or reverse for tail servo and set endpoints for no binding. Check collective-pitch range, and adjust for what you want. My reference is 16°of collective [pitch] in each direction (I run some pretty low head speeds, requiring a lot of pitch). I then can reduce it in the pitch curve for each flight mode, so the higher flight modes are normally 12°-13°.

Check cyclic range: each gyro asks for a different reference range of pitch to work properly. For instance, the Futaba CGY750 asks for 9°-10° (I use 10) and the Ace RC GT5 asks for 8°. I then check for binding at the extremes of collective, plus aileron/elevator.

To get the right collective and cyclic ranges and achieve no binding, you may have to play with servo arm lengths a bit on some units. I generally start with 60% P gain (transmitter controlled on most units). Check gyro correction directions for tail/elevator/aileron and pirouette compensation.

Fly and start adjusting the P gain until just below the area where it wobbles on a given axis. Further tuning of the D gain for stopping without bouncing is then done.

Last, I’ll tweak the I gain if the helicopter is not consistent from hover to fast forward flight. This is accomplished by checking things in a hover, such as pirouettes and hovering tumbles and rolls, then doing the same in fast forward flight.

For cyclic, I start with hovering rolls at full stick deflection, with the dual rate cut down to a comfortable rate, like 50-60%, continuing to roll into forward flight, [and] accelerating to the highest speed. The roll rate should not change. If it does, I tweak the I gain to achieve consistency.

CM: Any words of advice for newer pilots learning about flybarless setups?

GW: If you are adjusting and tuning and simply can’t get all the wobbles out and it’s very difficult to get I and D set properly, reduce the P gain. It shouldn’t always be the goal to get gains as high as possible. You want it to hold well, be consistent, and stop precisely without bouncing. If you achieve that, there really isn’t much need to increase gains further.

Don’t get discouraged with the process. Contrary to popular belief, the process is the same with all units. The terminology may be different, and the reference ranges for pitches may be different. There are devices that all do the same thing, [and are] offered from different manufacturers. You wouldn’t drive a car differently from a different manufacturer simply because the knobs/levers are in different locations.

Sources:

International Radio Controlled Helicopter
Society (IRCHA)
www.ircha.org

Written by Chris Mulcahy
RC Helicopters
Column
As seen in the November 2017 issue of Model Aviation.

There’s no denying that RC helicopters are flown primarily by men, but a growing number of women are flying them too. I recently had the chance to chat with Raquel Bellot, who earned the moniker “Lady 3-D” after traveling throughout Europe and competing in helicopter contests.

I was lucky enough to see Raquel fly at the International Radio Controlled Helicopter Association (IRCHA) Jamboree, held at the International Aeromodeling Center in Muncie, Indiana, a few years ago. She demonstrated her trademark style, flying with the transmitter behind her back. It was the first time I’d seen anyone fly like that with a helicopter, and I enjoyed watching her. I recently had the chance to chat with Raquel, so naturally we talked about helicopters!

Raquel’s trademark maneuver is flying 3-D helis with the transmitter behind her back.

Chris Mulcahy: Hi Raquel. Can you tell us a little bit about who you are and where you are from?

Raquel Bellot: Hello Chris! My name is Raquel Bellot and I’m an enthusiastic RC helicopter pilot. I’m from Spain. Valencia is the city where I live.

CM: What brought you into the RC hobby?

RB: I’ve been flying RC helicopters [for] 14 years. I started in this hobby because of my dad. He is an RC enthusiast as well. He started with boats, cars, airplanes, and then helicopters. Helicopters are his favorite machines. From when I was a baby, I always saw helicopters at home. To see my dad flying and fixing helis at home was like a lifestyle for me.

I decided to fly helicopters at the age of 15. Of course, my dad was my teacher. I did just a few hours on the simulator before [using] the buddy box with him. After just one flight with the buddy box, my dad told me that I was ready to fly alone. My first helicopters were a Raptor 30 and a Kyosho Caliber 50.

Raquel started flying model helicopters when she was 15.

CM: What kind of flying do you enjoy the most?

RB: 3-D style is my favorite one. I do enjoy 3-D maneuvers a lot, but I also practiced other routines in the past. When I started with helicopters, I focused my flight on practicing ability exercises. My dad taught me how to do it. (He was really good at competitions.)

In Spain, we had the famous “fun-fly competitions.” The goal of those exercises was to show your precision flying [of] the helicopter. For example, limbo, bottles, to rescue triangles, etc., so I practiced a lot of those exercises and I competed a lot in Spain. I always won the competitions.

Then I tried F3C, and I competed in the F3C championship, but I noticed that F3C was not for me—a little bit boring for me. So I started to fly 3-D style, and I’m addicted to 3-D now!

CM: How do you push yourself to learn new maneuvers?

RB: Of course, the simulator is the most important tool [on which] to learn new maneuvers. I always used the simulator to learn—even now if I want to practice something new. It’s also important to watch videos of other pilots when they are flying at the flying field, and also watch demos on the simulator about how to do some maneuvers.

I recommend visiting some international helicopter events to see how the pro pilots fly, and also to see the good atmosphere. It’s good for motivation and to push yourself to learn more.

In 2007, when I was learning how to fly 3-D, I just knew basic maneuvers. My dad and I decided to travel to the 3D Masters in the United Kingdom just to see the event. It was the first time that I traveled to an international event.

I was totally impressed with the 3-D level and talented pilots. I was shocked. I had never seen it before. I had a conversation with my dad on the airplane [flight] back home, and I said, “Dad, I will never fly like that, and I will never fly in a competition/event like that.” And he told me, “You just need a hard routine, but you can do it!”

As soon as I arrived home, I started to practice on the simulator every day, like three to four hours. I also flew all day Saturday and Sunday every week at the field. It didn’t matter if there was rain, wind, cold ... I was always at the flying field practicing.

The process from when I started to fly 3-D and to travel and compete was so fast. In 2008, I was doing demos at the 3D Masters thanks to my first sponsors. Then I was competing [in the] 3D Masters Expert class in 2009. It was the beginning for me in the world of 3-D helis.

Raquel Bellot poses with her Soxos DB7.

CM: Can you tell us what your current helicopter setup is?

RB: At the moment, I’m a factory pilot for Heli Professional. I’m flying a Soxos DB7.

• Motor: Kontronik Pyro 750-56
• ESC: Cool Kosmik 200 amp
• Servos: MKS X8
• Flybarless system: Microbeast
• Batteries: OptiPower 5,000 mAh 6S 50C and Ultra-Guard
• Blades: SpinBlades Black Belt 685mm and 105mm
• Radio: Spektrum DX9

CM: What is your favorite part of the hobby?

RB: I enjoy every part of the hobby. I like to spend hours with my dad, building and fixing helis together, flying at the flying field, traveling to competitions and events. But my favorite part is to meet pilots and to see my friends.

I love to visit new countries and events. I like to meet people, experience cultures, and food.

CM: Why do you think we don’t see more women in the hobby?

RB: When I started in this hobby, I was the only one doing it (at least in Spain, and also during international competitions and events). I didn’t meet any other girls flying helicopters, so I felt like the only girl in a male hobby.

Pilots always treated me very well—they accepted me. There are more female pilots at the moment. We can see the Girls United team doing demos during important international events. It’s an entertainment show for visitors, and also a way to motivate other girls to fly and to know a bit more about our fantastic hobby.

In my opinion, girls prefer other hobbies or sports, but not a hobby with motor machines. We don’t see many girls, for example, at Formula 1 [auto races], MotoGP [motorcycle racing], or driving karts. I don’t know why, but [it] looks like society has taught us that motor sports are for men. Thankfully, there are brave girls showing that we can do it.

We all know this hobby is expensive, and requires patience and to invest lots of hours to improve flight skill. If I’m honest, I spent half of my life with helicopters, without [a] personal life, just to study and to fly helicopters. It was a high compromise. But not all girls want to do it.

CM: What words of advice would you give to someone who is thinking about learning to fly helicopters?

RB: We have many ways to learn easily nowadays. In the past it was difficult, but now we have tools to learn quicker and better.

I recommend joining an RC flying club to see and talk with other helicopter pilots. The way to learn quickly is to fly with other pilots. Use a simulator, listen to the advice of good pilots, and visit some competitions/events. This will keep you motivated in the hobby. Don’t rush, and have lots of patience.

I know many people who wanted to enter this hobby and thought that they were going to be top pilots in a few months and get sponsors and free stuff. This is not the way to think. All of them quit the hobby very soon.

All hobbies and sports need time and consistency. To fly helicopters is not easy. We need consistency, patience, and high motivation. But the most important thing is to enjoy [the hobby]!

Thank you, Raquel, for taking the time to talk with me! Check out Raquel’s flying on YouTube or on her Facebook page.

-Chris Mulcahy
cspaced@gmail.com

Sources:

RB1-RC
www.rb1-rc.com/en

Raquel Bellot’s Facebook page
www.facebook.com/raquel.bellot.3D

IRCHA
www.ircha.org

Written by George Kaplan
Packed with features at a value price.
Product Review
As seen in the April 2018 issue of Model Aviation.

Bonus Video

Specifications

Modulation: 2.4 GHz FHSS HoTT system
Channels: mz-12, 12-channel; Falcon 12, six-channel
Power: 1,500 mAh LiPo battery, charges via USB port
Display: 128 x 64 Mono LCD
Antenna: Built-in dipole antenna
Transmitter
weight: 20 ounces
Receiver
weight: 0.28 ounces
Price: $199.99

Pluses

• A 12-channel radio and receiver for less than many other brands’ eight- or nine-channel systems.
• 2.4 GHz HoTT transmission (using up to 75 frequency-hopping channels).
• Model programming for airplanes, helicopters, multirotors, cars, and boats.
• Can be switched between Modes 1, 2, 3, and 4.
• 250-model memory.
• 10ms frame rates when used with digital servos.
• All switches and controls are user assignable.
• Mixing and multipoint throttle curves are available on all models.
• Real-time voice telemetry and announcements using preprogrammed or customized voice prompts.
• Wired or wireless buddy-box capable.
• Included LiPo battery charges through a standard USB connector.
• Can be used as a joystick for many flight simulators or games.
• Optional faceplates and skins are available to customize your transmitter.
• Falcon 12 receiver includes three-axis stability, as well as a flybarless helicopter and multirotor controller. It also includes real-time telemetry and can be expanded with optional telemetry modules (altimeter, GPS, ESC, and more).

Minuses

• No programming manual included. A 116-page manual can be downloaded from the Graupner USA website.
• Despite its name, the included Falcon 12 receiver only controls six channels.

The mz-12 Pro transmitter is a capable 12-channel radio with a variety of two- and three-way switches, rotary knobs, and digital trims. The plastic case can be customized with optional colored faceplates and sticker packages available on the Graupner website.

Product Review

If you’re anything like me, many of the products that you buy and use are those you’ve become accustomed to. I rarely step outside of my comfort zone, especially when it comes to my radio equipment.

Well, I’m stepping outside of my comfort zone and trying the Graupner USA mz-12 Pro system. With the benefit of hindsight, let me share a few things.

If you’re looking for a transmitter with a metal frame that has ultra-high-end programming with more than 25 point curves on every channel, multiple servo sequencing, quadruple rates, and incorporates the latest in web browsers with MP3 music playback, this is not the system for you. But if you’re looking for a solid system with a ton of features at a reasonable price, then I invite you read more.

I cannot cover everything that the mz-12 is capable of in this review. I’ll do my best to hit all of the major features, but to get a more in-depth look, check out the accompanying video online and in the digital edition.

Out of the box, the mz-12 Pro system consists of the transmitter, a Falcon 12 receiver, a USB charging cord, a warranty card, and a couple of pieces of double-sided mounting tape. Also included is part one of the instruction manual.

The all-plastic mz-12 Pro transmitter feels slightly smaller than some standard transmitters. My hands wrapped around the molded-in grips, making the sticks and all of the switches easily reachable. This transmitter case is molded in black with a red faceplate, switch cover, and matching red accents on the aluminum stick tips.

There is a wealth of optional faceplates, skins, and stick tips in a range of colors available on the Graupner USA website, so you can customize the mz-12’s look. Other notable features on the front are digital trims for the four main controls, a large LCD screen below the power switch, and two separate four-way controllers—one on each side of the screen.

Along the top of the case is a mixture of controls for the auxiliary channels. The port side has a two-position switch on the left and a longer spring-loaded, two-position switch to its right. Above these switches is a longer three-position switch with a spring between the second and third positions.

The starboard side has a short, two-position switch on the right with a rotary knob to its left. Above these is a longer three-position switch. Between the switches on the front face is a glossy Graupner logo that lights up or flashes red, depending on what’s going on.

Below the logo, an eyelet connects an optional neck strap. Centered between all of these switches is a large, sturdy handle that has a built-in 2.4 GHz antenna. On the back of the case, a large battery door can be removed to reveal the 1,500 mAh LiPo battery that powers the radio. The removable battery can be upgraded to a larger one.

Below the door are three small connectors. On the left is a 3.5mm DSC/headphone jack, used for wired buddy-box connection during training, or as a headphone jack to listen to the sounds and voice commands without disturbing others around you.

To update the mz-12’s firmware, add additional voice prompts, or use the transmitter as a controller for some PC games/simulators, the necessary connections are located on the back under the battery door.

The center (Data) connector allows you to connect to what Graupner refers to as a “smart box” or an external Bluetooth module. On the right is a micro USB port that can be used to charge the transmitter’s battery, connect to a computer to change settings, and use the mz-12 as a joystick with some computer games and flight simulators.

Before using any new transmitter, I adjust the stick length. I prefer longer sticks and the mz-12’s sticks work the same as most others on the market, with a two-piece tip that screws in and out on the barrel.

I also tighten the spring tension by removing the eight screws from the back of the case and carefully separating the case halves. Inside you have access to the spring tension adjustment screws. I also adjusted the screw on the throttle stick to give it a bit of a ratchet. It comes without a ratchet feel, but I’m an old-school pilot.

The back of the case needs to be removed to access the stick tension adjustments and the trim detent adjustments.

Switching on the transmitter for the first time surprised me. The screen glows blue showing the Graupner logo and some sounds automatically play. Decades ago, there was a cartoon series called the Ren & Stimpy Show. Of the many things that happened on the show, the characters had their own “commercials” for various things including “Powered Toast” and my favorite, “Log.”

Those of you who’ve seen the “Log” segments might remember that the commercial included the words “all kids love log.” Well, the first six notes of the commercial’s theme song are used as the startup sound of the mz-12, and I smile every time I flip on the power switch.

Immediately after the startup sound, the screen flashes and a loud, continuous, audible beep prompts you to choose whether or not to turn on the radio frequency (RF) section of the transmitter. To familiarize yourself with the transmitter screens and some basic setup, leave the RF off to save battery power. To power up the RF section, choose “Yes,” or simply wait and it will power on by itself.

If the RF section is powered and there’s no receiver for it to connect to, the transmitter will beep one time per second, nonstop, until you power down the RF section and connect it to a receiver or the mz-12’s battery runs out of power. If you power on with the throttle not in its lowest position, a different, louder alarm sounds and the screen warns you to lower the throttle.

When powered on, the blue glow from the screen displays much information at a glance, including the selected model, battery voltage, time since the last transmitter charge, various timers, flight modes, and the position of the digital trims. A series of symbols indicate signal and binding information, as well as receiver voltage.

The main screen shows the selected model, battery voltage, time since the last transmitter charge, various timers, flight modes, and the position of the digital trims. Along the top of the display is a series of symbols that indicate signal and binding information, as well as receiver voltage.

Pushing any of the buttons on the left-hand, four-way control will display the telemetry screen. From here, you can easily monitor any of the Falcon 12’s built-in telemetry, as well as any of the optional add-on telemetry modules you might be using.

As shipped, the telemetry provided by using just the Falcon 12 receiver is limited to receiver voltage. If you purchased any of the optional Graupner telemetry modules, however, the mz-12 could provide real-time feedback of altimeter, GPS, ESC, etc.

Everything I’ve explained so far is in the included manual, but there’s nothing about how to program in models, servo reversing, mixing, etc.

Perplexed, I visited the Graupner USA website and found that there is also a part two available, but only as a download. It has 116 pages of information about how to use the transmitter—that’s a lot of pages to print. You might be able to fumble your way through and get something that works for you, but you need the second part of the manual to use the full potential of the programming.

To get into the bulk of the mz-12’s capabilities, you need to move to the right-hand, four-way pad and click on the top (ENT) button. This opens all of the setup and programming screens, and by using both the left and right four-way pads, you can move your way through them.

This blue fluorescent screen is the heart of programming the Graupner mz-12. You can easily move between options and change the setting using the four-way pads to the left and right of the screen.

The Model Memory screen is where you can select, name, copy, and modify any of the 250 models that the mz-12 can store. Pressing the bottom button on the right-hand pad (ESC) will move you back one screen where you can access the Model Phases. If you’ve ever set up flight modes with other systems, Graupner’s model phases are similar to them, and as many as three phases can be set for each model.

The mz-12 can store up to 250 models of various types including airplanes, helicopters, multirotors, cars, and boats.

Servo Settings allows you to access the reversing, centering, and travel adjustments of any of the 12 channels.

In the Control Settings screen, you can assign the auxiliary channels (5 through 12) to any of the mz-12’s switches. Travel adjustment for these channels can also be changed here.

Moving to the next screen, Dual Rates and Expo [exponential] can be programmed for ailerons, elevator, and dual rates. Each can be assigned to work full time without a switch, as low and high rates on a single two-position switch, or on multiple switches.

The RF screen seems to be a catch-all for a number of functions. As the name suggests, the binding, range test, and RF on/off functions are all here. You can also change the stick mode (Modes 1, 2, 3, or 4) and set up the timer in this menu. The timer can be activated by any control switch or gimbal. I chose mine to activate with the throttle stick.

The next screen is the throttle (CH 1) curve screen. Because I have adjusted my throttle to activate the detents, there are more than 30 separate positions that can be adjusted. Without the detents, there could be more. Moving the throttle stick will move the position along the graph. By pushing up or down on the left four-way pad, you can adjust that part of the curve.

Mixing is the next screen and depending on the type of model, it shows the appropriate built-in mixes. Each can be assigned to a switch if you’d like to turn them on/off in flight.

For airplanes, there are differential ailerons, differential flaps, aileron-rudder, aileron-flap, elevator flap, elevator-aileron, flap-elevator, and flap-aileron mixing. For helicopters, there are pitch throttle, pitch tail-rotor, tail-rotor throttle, and aileron (or cyclic) throttle.

For multirotors, this screen is replaced by Throttle Cut and Timer menus, which allow various timers to be set, including a race timer.

Jumping to the next series of screens, Free Mix gives you the ability to mix even more than the previous mixing screen. Up to nine custom mixes can be programmed here.

The Basic Setting screen provides access to the battery warning voltage, button response speed, display contrast and light settings, country setting, and beep volume. The last settings adjust how the DSC, DATA, and USB sockets function.

The next screen is used to set up failsafes for each of the 12 channels. You can also set up a delay of up to 1 second before the failsafe activates. If you were to use the mz-12 as either the master or slave for training, those settings are in the next menu. Any of the 12 channels can be chosen for the pupil to control.

I have never owned or used a transmitter that had voice prompts, but I’ll admit that they are a nice feature. All of the voice prompt settings are in the next menu (Voice Switch).

Choose the appropriate prerecorded prompt—a woman with a British accent—whenever a switch is toggled.

You can also choose to create and import your own sounds. I made a series of sounds that are similar to Siri on an iPhone as MP3 files. There’s a free program on the Graupner USA website that can import those sounds and upload them into your mz-12 when connected via USB cable.

The last screen shows the radio-frequency identification number and installed firmware. I updated my firmware to the latest that was available on the Graupner USA website using the free program that I previously mentioned.

One last thing on this screen is the “default set.” This allows you to wipe the memory and put the mz-12 back into a factory setting—sort of. As I was playing around with the transmitter, shooting pictures, video, and learning the system, I wanted to reset everything, so I chose this option. It erased everything that I did, but it loaded a handful of multirotors into the first several model memories.

I thought I’d done something wrong and tried it again, but had the same results. Looking through the manual, I found that this is an intended feature. It’s no problem to delete those models from memory with a few trips through the menus. I also found that I had to reset the RF region back to America.

Switching the focus to the included receiver, you’d be correct to assume that the Falcon 12 was a 12-channel receiver because of its name, but it’s only a six-channel receiver. It’s compact at slightly less than 1.5 inches long and weighs less than 0.3 ounces. At one end are the six connections for the servos, ESC, and/or battery. At the other end is the antenna. An LED shines through the Falcon’s label when in use and blinks during the binding process.

Included with the mz-12 is a Falcon 12 receiver. The six-channel receiver includes built-in three-axis stabilization, as well as a flybarless helicopter and multirotor controller. It includes real-time telemetry and can be expanded with optional telemetry modules.

Binding is simple. Power up the receiver, wait 15 seconds or so, and the LED will begin to blink. Power up the transmitter, start the binding process, and it will usually bind within a few seconds.

Integrated into the Falcon 12 are three modes: Airplane (with three-axis stabilization), Helicopter (with a flybarless controller), and Multirotor. It also sends real-time wireless flight data recording to the mz-12.

In Conclusion

The mz-12 Pro system has more than enough features for probably 95% of modelers. You can step up to the optional 12-channel receiver if you need more functionality, and there’s a wealth of optional telemetry modules available.

I’ve been using the Graupner mz-12 Pro and the Falcon 12 receiver for a while, and now that I’m familiar with the screens, it’s logical and straightforward to program.

My only wish is that it had two more switches/sliders/knobs to control those last two channels, but not many of us need 12 controllable channels. It’s a great system and is certainly a lot of radio for the money. If you’re looking for a new radio system, or maybe thinking of changing from what you currently use, consider the mz-12 Pro.

—George Kaplan
flyingkaplan@yahoo.com

Manufacturer/Distributor:

Graupner USA
(855) 572-4746
www.graupnerusa.com

Written by Stan Alexander
What is scratch-built?
As seen in the April 2018 issue of Model Aviation.

Building is an open subject, especially for modelers. After reading multiple discussions online about what some consider scratch-built, plan-built, kit-built, or an ARF, I’ll try to explain it and hope that it doesn’t upset anyone. Here it goes.

Scratch-building a Scale model is taking a set of scale drawings (such as three-views) that show the outlines of the full-scale aircraft and then measuring the drawings. Add to that photos and other documentation that you have. The drawings are scaled up and a set of working plans from which to build are made.

Larry Botsford’s scratch-built Fiat CR.32 has a 98-inch wingspan, is powered by an O.S. BGX-1 3500 engine, and is painted with Klass Kote.

Greg Hahn’s Gotha G.IV is completely scratch-built with a 17-foot wingspan. Powered by two DLE-40 twin engines, it’s painted with Randolph dope and covered with Solartex.

Parts from the plans are cut out with a band saw or laser cutter and you begin to assemble the model. The aircraft is later covered and painted, and the scale details are finished.

Next are plan-built models. You can purchase, borrow, or find free plans then use these plans to cut out the parts, sticks, etc. Sometimes you can purchase a short kit, which usually consists of the shaped and formed parts, but you are still building from plans.

Greg Hahn’s plan-built model of a Nick Ziroli-designed Douglas Skyraider was enlarged to a 120-inch wingspan and uses a DLE-120 twin engine. Here it is shown on a bombing run.

Remember that all plans are not created equally. AMA has more than 8,000 sets of plans available through the AMA Plans Service, many of which are Scale models, but they run the entire spectrum of aeromodeling.

On tap next is the kit-built model. You purchase a kit, such as a Sig Manufacturing 1/4-scale J-3 Cub, then order all of the gear, covering, paint, markings, etc. and build from its included plans and instructions.

Ted Roman’s Sig Manufacturing 1/4-scale J-3 Cub is shown in Airship Squadron 32 colors. It’s powered by an O.S. 1.60 twin engine.

Randy Adams had this Balsa USA kit of a Nieuport 28C entered in Fun Scale. Built by Doug Cox, it uses a Zenoah G26 engine for power.

A 1/3-scale Balsa USA kit was the basis for Steve Eagle’s beautiful Nieuport 17. The 114-inch wingspan model is powered by a 3W 100 engine and is painted with automobile paint.

ARFs are usually delivered in huge boxes and are generally prefinished. You must add the gear, hardware, and radio system, but the hard stuff is mostly done for you. Believe it or not, you can compete in RC Scale with an ARF in the Fun Scale class.

There are fiberglass kits, carbon-fiber kits, balsa/plywood kits, and a seemingly endless variation of models from which to choose. I like plan-built models, and you can make modifications to plan-built, kit-built, or scratch-built models—ARFs, not so much, but adding details to any model is half the fun.

Dale Arvin’s Balsa USA 1/4-scale J-3 Cub has a wingspan of 108 inches. It uses an O.S. FS-120 engine for power. The covering is MonoKote, and it’s controlled by a Futaba radio system.

Adam Grubb’s beautiful DC-3 was built from a Fiber Classics kit. The model is painted with automobile paint. It features a 120-inch wingspan and it’s powered by two Y.S. 115FZ engines.

New Scale Plans!

Jerry Bates Plans has several new sets of plans for 2018. The 1/3-scale Rearwin 6000M Speedster has a length of 88.5 inches, a 128-inch wingspan, weighs 28 to 32 pounds, and uses an 80cc or larger engine. The plans cost $60. The only full-scale flying example known to me is a bright red Speedster that was restored and was at EAA AirVenture in Oshkosh, Wisconsin, several years ago.

The Mitsubishi A5M4 Claude is designed to 1/4 scale with a wingspan of 1081/4 inches. It was the predecessor to the A6M Zero and used mostly by the Japanese Imperial Navy as a carrier-based fighter. It does not have retracts! The model aircraft had fixed gear with wheel pants, and the wing is designed to come apart in three sections for transport. It’s fully aerobatic as well. The plans sell for $65.

A sideview of Mitsubishi A5M4 Claude plans created by Jerry Bates. The model features a 108.25-inch wingspan.

Jerry Bates has been drawing airplanes since he was a kid. He is one of the few designers who is still publishing plans and producing parts for his designs. All of his plans are drawn in CAD, so his plans are easier to understand, read, and build from.

A “proof of model” is always built with Jerry’s plans, so when you purchase his plans, they are well thought out with the servo installation, engine, hinges, and other small items that many designers don’t include.

The following is an autobiography written by Jerry Bates and gives a history of how he became a plans maker and model designer.

Jerry Bates had a passion for airplanes and drawing even before he could walk. He was born in the Panama Canal Zone to two ex-Marines who served during World War II. His dad worked for a government organization that was tasked with mapping Central and South America. He was chief cartographer (mapmaker) and charged with seeing that the mapping equipment was set up and operating correctly in each country. To say the least, they moved around continuously.

The organization had many ex-WW II aircraft for transportation and mapping, such as the C-46, C-47, DC-4, B-17, B-24, and A-26, as well as a couple of the “double-bubble” P-38s. There were numerous light airplanes and even a P-47 Razorback that was painted orange. Flying in those aircraft, and many others, was Jerry’s foundation for a love of military aviation. His dad’s early career as a mapmaker piqued Jerry’s interest in drawing what else, but airplanes.

Jerry Bates’ Fokker D.XXI is finished in a pre-WW II Finnish Air Force color scheme.

When he was back in the Canal Zone, he was either building model airplanes or exploring the jungles with his brother. The Canal Zone was a major point for the return of equipment and supplies used in the Pacific War campaigns. Numerous aircraft were stored and rebuilt there and given to other countries. Those boneyards became their primary playground.

Jerry’s parents returned to the United States in 1959. His dad continued his government employment and moved the family around every few years. The car bug bit Jerry by that time—he was in his early teens. Starting with sport car racing, stock cars, and then drag racing and street rods, it culminated with motorcycle racing and sales. Through all of this, he supported his family and his hobbies as a draftsman with several engineering firms. He recently retired from an engineering firm as a senior designer.

Motorsports could not keep him away from the airplanes, though, as he continued to build and fly models. He concentrated on Control Line and worked his way up to Precision Aerobatics (Stunt) competition. Jerry was also building models for others, and that is how he got his introduction to RC models.

He attended several RC Precision Aerobatics (Pattern) competitions, but just couldn’t make a comfortable connection with that area of the hobby. His RC friends got him to attend a couple of RC Scale competitions during this time. That did it for Jerry—the cars had to go in order to convert his shop and dedicate it to RC Scale aircraft models.

It was during one of these visits that he was introduced to the late Jack Dorman of Fort Walton Beach, Florida. Jack became his mentor, teaching him many techniques and introducing him to the “big names” of our hobby/sport. Jack and Jerry collaborated on a 1:5.5-scale P-40E Warhawk. Jerry drew the plans and Jack built the model. They successfully campaigned the P-40 and that was the start of Jerry Bates Plans.

At first, the plans were hand drawn. He would build the prototype model, fly it, and then make the molds for the various parts to be offered. Jerry did the vacuum forming and fiberglass part lay-ups as well.

With a full-time job, it became difficult to find time for new plans because so much time was required to make the parts and fill the orders. He now has several fabricators who make and ship parts to his clients. There are also several vendors that supply retractable landing gear to suit the plans.

Jerry has lately found a couple of builders to make some of the prototype models, allowing him time to make molds, etc., and thus having more time to develop new plans. The introduction of CAD has been a major change in the way plans are developed. In the past, drawing meant working on one set of plans at a time and staying with it until it was complete.

CAD allows the development of several plans within the same timeframe—not because CAD is faster, but because you can save the files on a hard drive and simply access them at a keystroke for additional information as the need arises. CAD also offers the opportunity to develop plans with more accuracy of the parts fit. At any one time, Jerry has six to eight plans under development.

Jerry’s path for the development of a set of plans might not be unique, but could be of interest, so we’ll lay out the process from conception to completion.

First, an interest must be sparked. For Jerry, that is easy; if it has wings, he’s interested. But normally the spark comes from a suggestion that is received from someone in the modeling community. His interest in the aircraft is usually from a historic standpoint. Once the subject is selected, he collects all of the historical data he can find, any factory drawings or publications available, photographs, three- or four-view drawings, and available plastic kits and model plans about the subject.

Jerry then selects the most accurate three-view upon which to base the plans. The three-view is compared with the information collected. If it proves to be scale, it will be used. Most often, though, the scale drawing is not scale, so he draws his own.

If fortune smiles [upon him], he finds a full-scale subject to measure. With the scale drawing complete, the model plans can be developed. It might take six to 10 months to complete a set of plans, depending on how long it takes to collect the required data.

After the plans have been completed, they are sent to several interested parties to critique. That process is used to check accuracy, construction technique, and to look for mistakes so that they can be made ready for construction.

A laser-cutting file is created and sent to a cutter so that the prototype model can be built. Plans errors that are found during construction are fixed, and the plans and laser-cutting files are readied. The cowl and canopy models are made, and the plans are offered to the modeling community.

Jerry’s plans are for the traditional type of balsa plywood construction. His philosophy for plans is to develop one with a scale outline, an airframe that is strong and lightweight, and one that utilizes the minimum number of parts to accomplish the building task. The advent of laser cutting makes this job easier because it allows for interconnecting parts. An airframe that builds quickly allows a modeler more time to incorporate scale details.

The primary purpose for construction plans is to impart information to the builder. That makes the way information is displayed on plans of utmost importance. Careful use of line weights is used to display that information.

Ease of construction is another important issue. The fuselages of most of Jerry’s models are built split along the engine thrustline. The top half is built on the top view of the fuselage plans. The horizontal and vertical stabilizers are added, along with the upper fuselage sheeting before removal from the workbench, making it easier to ensure that the stabilizers are square with the thrustline.

That assembly can be removed from the plans and the bottom of the fuselage built directly onto the top half. That method minimizes built-in warps and allows for quick assembly. Wing halves are built directly on the plans, utilizing building tabs to provide the correct washout.

Most of Jerry’s plans utilize the airfoils, incidences, and offsets of the full-scale subject. Both the size of the model and the radio systems that are offered today have made this combination successful.

You might have noticed by the plans offered that they are primarily for lesser-known aircraft, or were developed for a specific scale, rather than the aircraft normally seen at the flying field such as the P-51D, Corsair, P-47, etc. Jerry enjoys doing plans for unusual aircraft. They might not have a large market, but the process sure must be fun.

Time is still a constraint. You know the old adage—so many airplanes, so little time. That means he doesn’t have the time to fly much anymore. Jerry thought he would be missing that portion of the hobby more than he does, but he has as much fun drawing plans, and it makes it that much more enjoyable when he sees a model at the flying field that was built from his plans.

Builders and fliers are the key to the hobby. When you get a chance to pass it on, do so! Jerry has said if you keep building them, he will keep drawing them.

Update on Cessna C-165 Airmaster

I didn’t get nearly as much work done in 2017 on my Cessna as I had hoped. Family illness and other things got in the way. But now I’m back on it and finishing up the wing, servos for the ailerons, and flaps, as well as a more scalelike set of landing lights and navigation lights.

Tina Patton

Tina Patton is new to building Scale models and has tackled a good one as her first: a Balsa USA Sopwith Camel. Her husband, Bob, is a longtime designer and builder of large Scale models. I can’t wait to see the results.

Tina Patton is shown with her first RC Scale model, a Balsa USA Sopwith Camel. The author looks forward to seeing it fly!

Fair skies and tailwinds

Another beautiful scratch-built model at the 2017 RC Scale Nats was Art Johnson’s 1/3-scale Nieuport II.

Adam Grubb’s Waco YKS-6 from Pilot-1 Airplanes is an ARF with a 100-inch wingspan. Its O.S. FR7-420 radial engine sounds great! Adam flew it in Fun Scale during the Nats.

John Borton’s Pietenpol Air Camper was built to 1/4 scale with a wingspan of 84 inches. He scratch-built it from his own plans and powered it with a RimFire 120 electric motor and a Talon 90 ESC.

Sources:

National Association of Scale Aeromodelers (NASA)
www.nasascale.org

AMA Plans Service
(800) 435-9262, ext. 507
planservice@modelaircraft.org
www.modelaircraft.org/plans/plans.aspx

Jerry Bates Plans
www.jbplans.com

Written by Chad Budreau
Busy start to 2018
AMA in Action
As seen in the March 2018 issue of Model Aviation.

I often hear people complain that our federal government is too slow, wasteful, and inefficient. This is partially by design.

Here is a quick history lesson. After the American Colonies won their independence from England, there were many debates about how our country should operate. Founding fathers, including James Madison, Alexander Hamilton, and John Jay, expressed the need for a centralized federal government, but with enough fail-safe procedures to prevent the leaders from becoming corrupt or too powerful.

A slow-moving government was created to allow the public plenty of opportunity to engage and shape the regulatory and legislative process. I suspect our current government isn’t exactly what our founding fathers envisioned, but as a result, we now have a federal government that operates quite slowly.

This is an important perspective as to why we have Section 336 and why our work to refine and strengthen Section 336 takes a while.

With the growth of drones, the FAA is working as quickly as the federal government allows, but the agency simply does not have the resources to manage the operations we have been conducting for 81 years. Our safety programming spans hundreds of pages that address everything from flying site layout and competition rules, to event management.

Congress recognizes community-based organizations such as the AMA, that have well-vetted and time-tested safety programs that do not pose a risk to the airspace. As a result, Congress created Section 336 in Public Law 112-95 stating that those following the guidelines and operating within the programming of a community-based organization should be able to continue flying as they have been—safely and responsibly. In a sense, think of AMA as a private/public partner to relieve the workload from the FAA.

Section 336 is absolutely not a “get out of jail free card” and does not mean we are not under the enforcement purview of the FAA. Section 336 even clarifies in writing in that “Nothing in this section shall be construed to limit the authority of the Administrator to pursue enforcement action against persons operating model aircraft who endanger the safety of the national airspace system.”

I shared the quick history lesson because for a few years, you have been hearing AMA Headquarters discuss that we are working to refine and protect Section 336. I suspect that some of you are becoming numb to the government relations message, but know there is plenty of talk, and there have been many revisions discussed concerning Section 336 in Washington, D.C.

The revisions often stall because of the nature of the federal government, but 2018 might be the year that we see significant changes. We will continue to keep you posted via email, social media, online, and this magazine.

I hope I do not become the “boy who cried wolf” and I find myself asking for help and receive no response.

Busy Start to 2018

It has been a busy start to 2018 for the AMA Government Affairs team. At this year’s AMA Expo West in Ontario, California, representatives of AMA and the FAA Safety Team led a panel on current regulations of UAS. AMA President Rich Hanson, as well as Government Affairs team members Chad Budreau and Tyler Dobbs, participated in the panel, along with Ken Kelley from the FAA’s Airworthiness FAA Safety Team Program Managers/Point of Contact sUAS Educational Outreach Safety Promotion Program Office.

Additionally, earlier this month we participated in four Drone Advisory Committee meetings and we lent our expertise and insight into shaping the future of model aviation in the national airspace.

We continue to monitor legislation that could affect our hobby at the local level. We worked with lawmakers in Pitt County, North Carolina, and Washington state on legislative language to protect our members from potentially harmful laws. We also worked alongside clubs with flying sites located at U.S. Air Force bases in Arizona and Texas to discuss possible waivers for Temporary Flight Restrictions (TFRs) that would allow AMA members to continue flying safely at these sites as they have for many years.

It is important to note that since the start of 2018, more than 169 model aviation-related bills have been introduced at the state level. Although most of these do not appear to be problematic for AMA members, we are actively tracking each one to ensure that our members and our beloved hobby are protected nationwide.

Of the 169 proposed bills, there are currently 16 that we consider especially troubling. In each of these cases, we are actively engaging with legislators to improve the proposed bill. At this stage, we do not feel it is necessary for AMA members to become involved; however, the voice of our members is always important to protect our ability to fly model aircraft without burdensome restrictions. That’s why we ask members to remain engaged and monitor their emails, social media, and www.modelaircraft.org/gov for new information and ways that they might become involved with these issues.

FBI UAS Outreach

As you know, we have been enjoying our great hobby safely and responsibly for more than 80 years. Unfortunately, there is now some concern that extremist groups could use drones to inflict harm and cause serious damage. In an effort to understand friend from foe, the FBI has contacted AMA as part of its routine community outreach to ask for our help in staying ahead of this threat.

If your club receives a visit by an FBI agent, welcome him or her to the site. Educate the agent about our hobby and commitment to safety. If appropriate, offer flight time with a model trainer and AMA instructor.

This is a good opportunity to show someone new to the hobby the basics of RC flying and our commitment to safety. You might even end up with a new club member because we know this hobby is addictive.

Additionally, the FBI has asked for AMA members to be vigilant and help identify any unusual behavior. If you feel someone or something is in immediate danger, call 911; if the threat is not imminent, call 855-TELL-FBI.

Finally, we ask that you contact the AMA Government Affairs department at (800) 435-9262 and let us know if you are visited by the FBI or have arranged a flight time with someone from the bureau. We’d be glad to assist with whatever you need. Thank you in advance for your help with this matter.

—Chad Budreau
chadb@modelaircraft.org
Public Relations & Government
Affairs Director

Written by Scott Stoops
Flight Training
Column
As seen in the February 2013 issue of Model Aviation.

On a trip with family and friends to Mexico, we were lucky enough to end up in the last row of coach for the four-hour flight. Sitting across the aisle from a family friend, he queried as to why it seemed as though we were severely tilted nose-up, even in cruise flight. In my typical wordy fashion, I proceeded to outline the basics of flight and specifically the angle of attack (AOA).

Seeing his eyes glaze over after a minute or so, I decided that this column would make a better vehicle for that discussion. Let’s explore AOA, some common misunderstandings new pilots have about stalls, and some common recovery techniques. Let’s start from the beginning.

Wings create lift. They do this primarily by manipulating the AOA. AOA is the difference between the chord line and the flight path or relative wind of a wing. Not unlike sticking your hand out the window of a car with it tilted slightly up, a wing creates down force through both its shape, but primarily, the angle it addresses the oncoming air. This is AOA (see Figure 1).

Figure 1

Although the basic shape of the airfoil contributes to the efficiency of the wing and its ability to create lift, the primary factor in lift creation is AOA. Based on the design of the wing and airfoil section, there is a maximum AOA at which the wing section will continue to produce lift. Flight beyond that AOA causes the airflow to become extremely turbulent and detach from the upper surface of the wing. This detachment results in a loss of lift, or a stall. The specific stalling AOA is a constant for that particular wing.

Stalls have absolutely nothing to do with a power failure of the motor or engine. In fact, unpowered aircraft such as sailplanes can also stall. Stall is an aerodynamic term that only relates to exceeding the critical AOA.

During normal flight in most types of airplanes, we avoid flying the aircraft at or close to the critical AOA. It is, however, important to be familiar with the stalling characteristics of your model. Learning to stall your model allows a higher level of awareness of the energy state of the airplane with regard to AOA. Practice is the only way to become familiar with and competent at stall and recovery.

For the airplane to stall, an AOA that exceeds the critical AOA must exist (see Figure 2). In the case of practicing stalls, the best place to start is from level flight with plenty of recovery altitude. You can intentionally stall the aircraft by increasing the elevator input and holding it in an increasing pitch attitude while reducing the power of the motor.

Figure 2

As the aircraft exceeds the critical AOA, airflow over the wing will “detach” from the wing’s upper surface, causing some buffeting and usually a pronounced pitching moment toward a nose-down attitude. Most models have a critical AOA of approximately 17°. Recovery is simple, but not instinctive.

With the nose now pointing slightly down (probably below the horizon), you must reduce the up-elevator input to let the wing recover to a flying AOA. This is not instinctive, because in normal flight we would apply up-elevator when the nose is below the horizon to correct for level flight.

In stalled flight, it is critical to allow the wing to start flying again by lowering the AOA even further. Often, simply releasing any elevator input back to neutral is enough to get the recovery started. This reduction in AOA generally coincides with an increase in thrust and, once the wing is no longer stalled, a gentle correction back to level flight.

Stalls in All Attitudes

Now for the confusing part! The previous example was for level, decelerating flight. Stalls occur when the critical AOA is exceeded, which means they can occur in any pitch attitude. A stall can occur when the aircraft is pointing straight up, straight down, inverted, or at any pitch attitude as long as the critical AOA is exceeded. This is generally tied to a large elevator input, but can also occur with small inputs at higher speeds.

A stall can occur at any airspeed (it is not necessarily a slow speed event, but rather, a high AOA event). This can be confusing to new modelers, because the traditional diagrams of the stalling AOA depict an aircraft in level flight as I have explained.

A model can be stalled going straight up in a loop. If the pilot pulls too hard on the elevator control stick (displacing the elevator up), the critical AOA can be exceeded and the wing will stall while the airplane is pointing straight up. The same is true if the pilot pulls too hard on the elevator during the backside of a loop while pointing straight down.

A good indicator that the model’s AOA is near the critical AOA is the position of the elevator. For the AOA to be high, the elevator has to be significantly displaced. So, wings stall at a specific AOA, not at a specific pitch attitude (see Figure 3).

Figure 3

3-D Flight

The next logical question would be how 3-D airplanes can be flown beyond the critical AOA if lift significantly decreases when the wing stalls. The simple answer is thrust. They use thrust to replace the lift lost from the stalled wing.

If you’ll note, most 3-D airplanes have dramatically oversized flight controls and optimized airfoils that allow full control through thrust vectoring and clean transition in and out of stalled flight. As your skills improve, consider learning some of the basics of 3-D flight, because it can only make you more comfortable flying at AOAs around and even beyond the stall!

Take-Away

Although it can be scary to slow your model to the point where you’re uncomfortable with how it is going to perform, learning stalls and stall recovery is critical to becoming a well-rounded RC pilot. Start high, and with a buddy box if necessary. Most importantly, remember that simply releasing the elevator input will often allow the model to recover on its own!

In the columns going forward, I’ll do my best to further explore stalled flight through some 3-D maneuvers as well as snap rolls and spins, so give the basic stall a try.

Fly safely, and remember that learning is fun, and fun is what this great hobby is all about.

-Scott Stoops

Written by Greg Gimlick
Electrics
Column
As seen in the August 2014 issue of Model Aviation.

We all run into problems now and then. It doesn’t matter if you’re new to electrics or have been doing it for years. The key is knowing how and where to look for the things that might be contributing to the problem. You don’t need to be an engineer, but it helps to have a plan and to be organized.

Tools of the Trade

It doesn’t take much, but there are certain things all electric fliers should have: a watt meter of some sort, a battery meter (to check individual cells in a pack), temperature gun, voltmeter, balancing charger, and a program such as ElectriCalc or MotoCalc.

None of these are expensive and there are calculator programs online at some of the vendors’ websites, but I suggest buying one of your own to help you evaluate projects. They are approximately $40. If you have a good battery checker, you might even get by without a digital voltmeter, but they’re so cheap now that I’d suggest owning one anyway.

Finally, I love ESCs that have some sort of data-logging capability. If you don’t have one, you can buy a small data logger from places such as Eagle Tree Systems that will give you critical data. Some radio systems are also incorporating telemetry that can record motor data. This type of information is invaluable. Without data, there is no diagnosing a problem.

Try to use an ESC that includes data logging or a separate device such as the Eagle Tree eLogger. Mine is an older version, but it still works great. Most ESCs have programming cards available so you can check the settings of the ESC at the field and make changes.

Be Realistic

I frequently receive questions about why a system is giving someone only 5 minutes of flight time when it “should be giving a lot more.” The first thing to do is determine if your expectations are realistic. If it’s a 5S system drawing 80 amps from a 5,000 mAh LiPo pack, it’s only going to run 3.75 minutes. How do I know? Easy …

A 5,000 mAh (5 amp-hour) pack has 300 amp minutes. To determine that, multiply the 5 amp-hour rating by 60 to get the amp-minutes (5 amp-hours x 60 minutes = 300 amp-minutes). That’s the usable time for the pack and if you divide that by the 80 amps you’re pulling, you get 3.75 minutes of flight time (300 amp-minutes ÷ 80 amps current = 3.75).

Know how to interpret data logs. I recently had a request from a modeler for some help and he provided the logs from three flights. This was great! The problem was that he told me the average current was 35 amps when it was actually closer to 60.

Everyone needs a battery checker. These can range from a $3 to a $30 model. All will display total voltage along with individual cell voltage, and one will determine internal resistance.

What he didn’t realize was that the data log included the time the battery was plugged in to arm the system—then it sat for a couple of minutes while he got ready to fly. That time was spent at zero or near zero current draw and figured into the total time when it averaged the flight. It saw the flight as the time between arming and disarming.

Within the program to evaluate the logged data there is a way to pull the parameters in to only see the actual flight time. That is the time we’re interested in and the real data. It’s an easy mistake to make and easy to fix. When we got the actual average current figures, the total flight time was within reason.

No Shotgun Approach!

Please, please, please … if you take nothing else away from this column, take this: do not make multiple changes at once! I get questions from people who wonder about a duration or heat problem and they’ve made several changes at the same time. Do one thing and see what it does for your issue.

If you make several, you don’t really know which helped or hindered your progress. Remember your high school science class and use a scientific method such as follows:

• Ask a question.
• Do background research.
• Construct a hypothesis.
• Test your hypothesis by doing an experiment.
• Analyze your data and draw a conclusion.

A balancing charger is a must! These range from $30 to approximately $200. The best will interface with a laptop and log results, including internal resistance.

Think about your problem, determine some possible causes, and take an action to correct it. Only one action! Reevaluate and go to the next solution.

Did you make some progress with the first? Is there another option using the first attempt (different propeller if you’re trying propellers, etc.)?

This is common-sense stuff, but we all get in a rush to get flying and will often throw the kitchen sink at a problem.

Think About Common Things

I could have stated, “Use the KISS principle,” but you get the idea. We sometimes overlook the obvious and go far deeper into something than necessary.

Did you use the suggested propeller? Did you grab the right battery pack? Is the pack fully charged? Are all of the cells good? Is your wiring done well? Are the connectors of good quality? Is your solder work done well? Are your ESC settings correct? Is your transmitter properly set?

If you have a watt meter (top), you might get away without having a digital voltmeter, but they can be a big help in diagnosing some problems.

In other words, don’t start calculating commutation frequency and exact pulse-width modulation settings before eliminating the obvious. I always assume I did something wrong before blaming the equipment. After I rule out my own error, then I can move on.

Wrapping It Up

I’m going to expand on some of this next time, but I hope this brings some common-sense thoughts back to the forefront of your diagnostic method. I hope you don’t even need to diagnose a problem ... but sooner or later, you will.

-Greg Gimlick
maelectrics@gimlick.com

Sources:

ElectriCalc
www.slkelectronics.com/ecalc/index.htm

MotoCalc
www.motocalc.com

Eagle Tree Systems, LLC
(425) 614-0450
www.eagletreesystems.com

Written by Greg Gimlick
Electrics
Column
As seen in the October 2014 issue of Model Aviation.

My last column, in the August 2014 issue, covered some basic thought processes necessary to diagnose a problem with our electric systems. I will continue that thread with a focus on some common problems.

Excessive Current

Excessive current is something we all eventually run into. Whether it’s truly excessive or simply what we should expect, can be the stumper.

Assuming you’ve used the exact components recommended by a manufacturer, you should closely match their performance and duration. If you’ve done that and are not seeing the expected results, then you need to look for the reason. Be sure that it is excessive and not an unrealistic expectation. Check my August “Electrics” column for more on that.

These magnets became loose and broken, causing excessive current, friction, erratic operation, and heat, which destroyed the motor.

Here are some common causes for which you should check:

• Ducted fan: check to be sure the blades in your fan unit are not contacting the shroud. This can cause friction and force the motor to work harder, which means more current.
• Geared or helicopter applications: setting the gear lash or belt tension too tight will cause the motor to pull excess current. Check to see that they are properly set.
• Worn bearings: this causes friction and will pull more current. Boca Bearings is a good source for replacements.

Poor Solder Joints

Whether you or the factory made them, look over the solder joints and see if they are secure and done well. If they are dull and rough looking, they are “cold joints” and will affect the circuit. The only recourse is to correctly re-solder them.

Motor Mounting

Check to see that the motor is spinning freely when it is mounted in the airplane. That last part is important, so read it again!

I recently ran into a situation where the motor spun freely on the bench, but when installed in the airplane, the shaft’s retaining collar rubbed the hole it fit through on the firewall/mount. This caused friction on the shaft when installed and drew extra current. Had I not checked while it was installed, I would have missed this problem.

The shaft collar barely clears the opening in the mount, but it’s smooth and doesn’t touch the edge. The wires exit along the side of the motor and must be secured to prevent contact with the rotating motor body.

The shaft collar barely clears the opening in the mount, but it’s smooth and doesn’t touch the edge. The wires exit along the side of the motor and must be secured to prevent contact with the rotating motor body.

Vibration

We’ve come to expect a smooth-running aircraft because of electric power, so when it doesn’t run smoothly, there has to be a problem. The biggest culprit is often the spinner. Just because you bought an aluminum spinner doesn’t mean it will run true. Quality is all over the place, and some cheap imports have shown me real challenges.

Remove the spinner if you’re using one and check the vibration again. Don’t forget to remove the spinner backplate. If it runs smoothly, work on the spinner with a balancer, etc. until it is right. If you still have a vibration, check the propeller balance. Always balance a propeller before using it! I frequently use APC “E” propellers and one will be perfect while the next might be slightly off. Never assume they’re all balanced, even if it seems that way.

Bent Motor Shaft

This is sometimes easy to see and other times it takes a dial indicator and test setup to see if it’s a problem. If you can see the shaft wobbling as you rotate the motor, it needs to be replaced. Many manufacturers make this an easy task, while others make it easier to throw the motor away.

More Vibration

Sometimes it seems fine on the ground, but in the air, we notice a vibration or “dance” that doesn’t appear normal. Think about airframe reasons.

Loose landing gear and wheel pants can cause in-flight movement. Are you using a stabilization system? If the gains are set too high, it will wag or roll. If the gains are right, but the receiver/stabilizer is moving because of poor mounting, that will cause it, too.

The blades of a ducted-fan unit have close tolerance and can contact the shroud. Fan units require balancing and close tolerance monitoring.

Erratic Motor Performance

This could be a column in itself, but I’ll try to cover it briefly.

• Check your connectors from the motor to the ESC and ensure they aren’t shorting to each other. Often bullet connectors are slightly exposed when connected. Although there is heat shrink over the main section, if all three connectors are next to each other, they can arc and cause weird electrical voodoo.
• Check your ESC settings to ensure you have them properly set for the motor setup. Factory defaults are correct 99% of the time. Understand what each setting means and read the help files for your ESC.
• Did you wind your own motor? Many hobbyists enjoy doing that and there are great motor kits available.
The wires in the motor have extremely thin insulation on them so they are easily nicked. This can cause a short that is often erratic rather than a dead short, preventing it from running. Check the continuity of your circuits if you wind your own motors.
• Check your battery packs. Connect a meter to the pack and see if flexing it, shaking it, etc. has any effect on the voltage reading. If so, that is a major problem and must be fixed or replaced. I don’t advocate cutting open LiPo packs, so talk to your vendor about a replacement if it’s a new pack. If you attached the connectors, check to be sure they were properly done.
• Check your motor wires to ensure that they aren’t rubbing against the rotating case of an outrunner motor. This is especially easy to have happen in the narrow nose of an electric-powered sailplane. Secure all of the wires out of the way and add an extra layer of tape just to be sure.

Excessive Heat

Assuming the timing is properly set in your ESC settings, the motor shouldn’t get scorching hot, nor should your ESC. Provide adequate cooling air intake to the motor/ESC and equally important, allow a spot for the air to get out! The rule of thumb is to have twice the outlet area for the inlet air.
In other words, if your inlet air hole is 4 square inches, your outlet hole should be 8 square inches. Don’t pack your ESC so tightly into the fuselage that it can’t get any air. Some have heat sinks and others don’t, but all of them need some airflow.

Wrapping Up

The list of possible problems grows and grows, but none of it is beyond the scope of the average modeler to find and fix. Hey, if I can do it, you can too!

-Greg Gimlick
maelectrics@gimlick.com

Sources:

Model Aviation Digital Library

Written by Mark Fadely
Radio Control Helicopters
Column
As seen in the July 2009 issue of Model Aviation.

Hi, everyone! Thanks for checking out this month’s column. We cover the coolest aspect of RC aviation. I am referring to helicopters. This is the place where we cover all things rotary.

If you are new to the helicopter side of RC, you have an exciting world of discovery ahead. It takes a long time to gain enough knowledge and skill to control these machines. As experienced helicopter pilots know, there will be many roadblocks to becoming a successful flier.

How would you define a successful pilot? Would it mean that he or she could fly a great 3-D routine? Or would you say a pilot who can merely hover is successful? I think a successful pilot is one who flies in a safe manner and can bring his or her helicopter back in one piece.

A number of factory-sponsored pilots push their flights to the limit all the time. They pay for those daring flights with a number of crashes. When you get all your parts for free, the wrecks are not a big deal. For the average pilot, frequent accidents take the fun out of the hobby.

Crashes are a part of all RC aviation. Minimizing them is usually the goal, but you must accept the fact that your pride and joy may not return in the same condition as when it last took to the air.

During a crash, sharp parts can fly in all directions. Always maintain a safe distance from the machine.

Wrecks damage our egos but, more important, they can severely injure people too. Personal-injury crashes are on the rise in the helicopter segment of RC. Statistically, our hobby is safer than ever, but there are more helicopters being flown than in past years. More helicopters equals more accidents.

I ask everyone to take safety seriously. Most pilots are safe in their routines at the flying field. We need to help newer pilots understand the real dangers involved with our machines. Whether you are a new pilot or a seasoned flier, please help when you can to keep things safe.

AMA member Jack Martin sent me a note of concern about safety. The flying season is in full swing, which means more helicopters will be in the air than at any other time of year. Jack is going to tell us a little about himself and share his experience as his club’s safety officer.

“I am 56, a former dealership car mechanic, and later an EMT and paramedic in Las Vegas, Nevada. Now we live in Washougal, Washington, as we followed my wife’s career to Portland, Oregon, just across the river. I am now retired for medical reasons.

“My wife of 22 years and I have two grown boys. My interest in aircraft started at age three. I built models as early as four years of age, then balsa and tissue rubber band power at 10. I struggled with RC at 23 and could barely afford a Sig Kadet airplane.

“Back in those days, I would dream of how cool it could be to have RC helicopters or real turbine aircraft. It was really not even a dream back then. Now we have all these neat electronics. Back then a proportional radio was the big thing.

“I left the hobby for several years for a career and to raise a family. I would drop in now and then, testing the helicopter waters in 1987, but I was never able to get the hang of it. I jumped back in with both feet in the year 2000, settling on scale aircraft in general, particularly scale helicopters. My careers have taught to me to think about what if such-and-such happens as a normal part of my everyday life.

Stephen Bell inspects a postcrash tail assembly. A broken tail blade caused a loss of tail control.

“I am Safety Coordinator at my field, a CD, turbine CD, and I fly fixed-wing and rotary-wing aircraft. I hold a rotary turbine waiver. I have a very real concern about helicopter pilots in general. I prefer helicopters, so I am not picking on the ‘species’ so to speak.

“In the last eight months, two people that I know have been severely injured/maimed by helicopters. In both instances the pilots fortunately had time to get at least one, if not both hands up to protect their heads. These could have been killers. One was a true accident, the other a mental lapse by the pilot.

“I have noticed that helicopter pilots in general have a very dangerous tendency to be close to their helicopter while it is spooling/ spooled up. Things can happen so very fast with a helicopter.

“As a group, RC pilots tend to not consider the possibilities of ‘what if?’ This, along with being too close to the aircraft, is a recipe for a severe injury. Those spinning things on the airplanes may be at a faster RPM, and are just as terribly dangerous, but other than starting and such, the spinning thing is way far away. This is not so with helicopter pilots.

“I frequently have seen pilots spool up to ungodly speeds less than 10 feet from themselves. I had to speak to a gentleman at my field one day because I just could not watch him hover a .90-size helicopter with the blades only three feet away! The dude got mad at me when I confronted him!

Large-scale helicopters such as this Puma can pack a lethal punch if the flight goes awry. Those rotor blades are more than 5 feet in diameter!

“A few weeks later he came back and thanked me because he had seen a failure when someone was doing the very same thing, only that time there was safe distance. It made him think.

“So what is it we don’t consider? For one, servo failure is often forgotten about. Helicopters abuse servos. Scale flight is not as damaging as 3-D, but all helicopter flight is hard on servos.

“Have you ever seen what can happen if a servo goes hard over due to a bad pot? I have had the misfortune twice. I never knew a helicopter could get upside down so fast. No one ever seems to consider the possibility of a servo failure. One of the instances was with a brand new servo and I don’t buy cheap servos either.

“Can you imagine how severely the dude hovering three feet away would have been hurt if his aileron servo failed? It would have taken the top of his head off so fast, I shudder. I guess if you have to go, then that is a fast way!

“Here is another scenario that happened to me: resonance. I was spooling up a large 1.8-meter turbine helicopter and it went into ground resonance and blew up on the ground. Blades blew by me at knee level. I got lucky. Some parts were as far away as 100 yards! I was 50 feet away from the helicopter.

“Another friend was spooling up his helicopter, testing a setup. He was about 40 feet away, maybe less. A tail blade let go, he heard it whiz by his ear. It went through some ply siding on his garage. A 120-mm tail blade!

“He always spools up with the tail not pointed directly at him. Good move, my friend. So, don’t spool directly inline with the tail either guys or gals. Blade grips can let go. This dude spooled up and took off at too high a head speed. His grips let go at about 20 feet up.

Although it is acceptable to fly within 25 feet of yourself, parts sometimes land more than 100 feet from the crash.

“I was 100 yards away and one blade went past me and landed on the grass, undamaged. The other blade was found two months later and it also was pristine, almost directly below where the mechanics went.

“What was interesting, I watched the one blade as it made its traverse. It was spinning on its long axis giving it a ballistic effect, and made a sweet arc, burying the tip into the soft, wet sod about 20 feet back. I inspected the blades, he is still using them!

“Another person I know is a very lucky you know what. He thought he could land a gasser on the stern of a boat traveling on the ocean. It was a small pleasure craft, and he was on the boat too. Well, things didn’t go as predicted and the helicopter came into him. There was no room for error, no room for escape, and no thought to the possibility of ‘what if?’

“This type of incident can give the whole hobby a bad name and we need to think about that. Even if it is not at a sanctioned field or event, what we do can have a serious effect on the entire hobby. He was able to use his hands six months later, [after] several surgeries, loss of work, and so on. He does still fly, but never close to himself any more.

“We helicopter pilots, as a group, need to be more aware of the dangers we face, consider them, and incorporate them into greater safety margins on the ground. I don’t want any more of my friends to show me how they saved their lives with their hands.

“These incidents are going to happen. When they happen is a big if. Therefore, the only common sense approach is to start looking out for the ‘what if’ scenario so we can prevent it or decrease the severity of it.

This dangerous situation occurred during a tandem demonstration flight. The helicopter was too close and is going toward the other pilot’s blind side.

“All of these lucky instances were the result of adequate distance from the helicopter. They happened to competent pilots. I hear these types of stories all the time.

“Pooh happens folks; prepare for it. Give yourself some distance. Save yourself from maiming. Physical therapy is costly, being in the hospital is costly, and losing income is costly. Injuring your ego—priceless!”

Thanks for the provocative stories and information, Jack. You have been on the front lines as a paramedic, seeing things that most of us are not exposed to. I find it interesting to hear from people who work in the medical community. You have a different outlook on life and you know that accidents do happen.

Thanks to you for reading what Jack wrote. Safety is not something we want to think much about, because it seems to take some of the fun out of our flying. We all need to be responsible pilots and not lose sight of safe flying practices.

-Mark Fadely

Written by Larry Kruse
A traditional aircraft design for the new builder
Construction
As seen in the May 2018 issue of Model Aviation.

Specifications

Type: Sport model
Wingspan: 30.25 inches
Length: 23 inches
Weight: 7.2 ounces ready to fly
Wing loading: 6.75 ounces per square foot
Motor: Great Planes RimFire 250
Propeller: 7 x 4 APC Slow Flyer
Battery: 2S 500 mAh LiPo
Radio: Tactic TTX 650 transmitter;Tactic TR624 receiver

Download free plans

Download full-size plan (33.76 x 27.82" in JPG format)
Download tiled plan (15 8.5x11" pages in JPG format, zipped)

Order prints from AMA's plans service

Construction

The idea for this model came from a telephone discussion with Model Aviation’s Editor-in-Chief Jay Smith, about a “beginners” theme he was planning for the May 2018 issue. The discussion centered around a design for those who had entered the hobby by way of RTF or ARF models, but who now wanted to build something of their own.

Central to that conversation was designing an airplane that would teach traditional building skills to the uninitiated, but would also be easy to build for anyone, regardless of the experience they brought to the project.

Having mentored five teams of high school-age students during the last five years as they built airplanes for a statewide competition, several things had become apparent to me. Because most of those students had never before built a model airplane, it was evident that one problem area was the daunting complexity of many of the available wood kits. That spoke to the need for simplicity.

They were not initially adept at handling and cutting balsa wood, so a small number of large parts with ample gluing surfaces needed to be incorporated in the design. Finally, covering a built-up framework with today’s heat-shrink film posed many problems. That led me to an all-sheet-balsa model that would essentially be complete after it was assembled and sanded, thereby eliminating some of the complexity.

I have built three of my late friend Dee B. “Doc” Mathews’ airplanes, originally kitted by Ace R/C and intended for four-stroke engines. I have never been so pleased with a series of designs in more than five decades of model building, and I was certainly influenced by their elegant simplicity and functionality.

I tried to incorporate those same principles in the little 30-inch shoulder wing aircraft that I sketched, requiring the builder to perform the time-honored tasks of the hobby—learning to cut balsa; assembling and gluing together a straight, well-aligned framework; and sanding it to an acceptable shape and smoothness after it was built.

These are all “old-school” practices and techniques that beginning builders could master and would serve them well as they became more than simply model consumers. In short, that’s how Old School began as I sketched out lines to make the idea a reality. The name just seemed to fit.

Preparing to Build

Getting the necessary wood, supplies, and powertrain together before the actual construction begins saves time at the start of any building project. Study the plans to determine what sizes of sheet and stick balsa, wire, plywood, and miscellaneous items, such as control horns and wheels, will be required to complete the model. It’s also a good time to acquire the motor, ESC, and battery. I used the Great Planes RimFire 250, Silver Series 8-amp ESC, a 7 x 4 APC Slow Flyer propeller, and a 2S 500 mAh LiPo battery in the Old School; however, any equivalent power system would work.

Opting for a larger system would be problematic because of the increased weight and increased wing loading. In model building, weight is the enemy. Part of keeping the weight down is using only two or three thinned coats of clear nitrate or clear Sig Lite-Coat dope, and sanding lightly between coats.

The target weight for the airplane, including the power system, should be 7 to 8 ounces and no more. The prototype weighed 7.2 ounces, which was a comfortable weight for the setup.

Pre-Kitting the Airplane

Another time-saving technique is to “pre-kit” the model—that is to cut out all of the parts before starting the building process. As the photos show, all of the parts are simple and easy to cut out by making poster board templates to trace onto the appropriate-size balsa sheets. A soft lead pencil is better than a pen for tracing so that you don’t leave ink residue that’s hard to sand off.

The basic fuselage pieces are shown. Note the 1/16-inch doublers on the rear of former F-3, and the doublers for the fuselage sides. Follow the instructions in gluing up the fuselage side doublers, including trimming 1/32 inch off of the right side fuselage doubler after it is installed for the required right thrust, and waiting to glue in the nose doublers until after the firewall is epoxied in place.

A single-edge razor blade or X-Acto knife with a sharp blade will work well for cutting out the balsa parts, but I prefer to use a scalpel. There are only two plywood parts: the fuselage former F-2, which is 1/16 plywood, and the motor mount is 3/32 plywood. Both can be cut out using a razor saw, but a jigsaw or band saw will make for easier work.

Note the holes that are cut in the motor mount for cooling purposes. The holes don’t have to be drilled to the pattern shown, but air openings for cooling will need to be made, depending on what motor you select.

The motor mount and the rails for the battery platform have been added in this photo. Note the manner in which the landing gear is stitched and then epoxied to former F-2.

Building the Wing

The wing structure is slightly different than even an experienced builder might have encountered. I chose an all-sheet-balsa Jedelsky-style wing for its strength and simplicity. It is built using two sheets of balsa placed at an angle, creating an undercambered airfoil.

The triangular ribs serve as angle guides and then the upper surface of the wing is sanded to an airfoil shape. Although the Jedelsky wing is most often employed in Free Flight models, some notable old-school RC sport models, such as the 1970s Honker Bipe, used it to good effect.

After cutting out the two 1/16-inch main panels, mark the rib locations on the bottom side of each. Select one panel, pin it upside down to the workbench, and glue the triangular ribs in position, matching the rib’s high point with the front of the panel. The 1/8-inch rib is glued flush with what will be the center of the wing.

The bottom of the right wing panel shows how the Jedelsky wing is constructed. Overhanging portions of the ribs, both fore and aft, are simply sanded on the bottom to a rounded shape after the wing is complete. That also holds true for the wingtip, which should be sanded to the outline shown on the plans.

After the ribs are dry, turn the panel over, again pinning it flat to the work surface. Now take the 3/16-inch leading edge (LE) and taper one side of it so it mates seamlessly with the 1/16-inch panel. Put glue only on the top of each of the exposed ribs and set the LE in place, gently shoving it back against the full length of the 1/16-inch sheet.

When it is dry, turn it over and glue the seam between the two pieces from the bottom side. Build the other panel the same way. After the two panels are complete, sand the top side of each 3/16-inch LE to a rounded airfoil shape, using the template furnished on the plans as a guide.

The dihedral angle is set by propping up each panel 11/4 inches at the tip, holding a sanding block vertical to the work surface, and gently sanding each center rib. Trial-fit the wing panels, sanding again as needed, and then pin down one panel while raising and supporting the other panel 21/2 inches at the tip.

Thick CA or epoxy can be used to glue the two panels together. Sand the wing, and then using thin CA adhesive, glue a 5/8-inch strip of lightweight fiberglass over the seam to strengthen the dihedral joint.

Insert the split dowel rubber band bumpers in the LE adjacent to the fuselage, and add the plywood doubler plates to the trailing edge (TE) as shown.

The wing has a 5/8-inch strip of lightweight 1/2-ounce fiberglass attached with CA along the dihedral joint. The 1/32 plywood doubler plates are glued to the trailing edge, and split dowel “bumpers” are inset into the wing’s LE to protect it from being indented by the hold-down rubber bands.

Fuselage Construction

Some additional work needs to be performed before the actual fuselage assembly begins. The .062 music wire landing gear needs to be bent using the pattern provided on the plans then it needs to be “sewn” and glued to fuselage former F-2.

Instead of using a needle, I dragged roughly 1.5 inches of heavy carpet thread through a small puddle of CA glue. When the end of the thread had cured, it had sufficient strength to poke through the holes drilled in the former, just like a needle. After the thread is wrapped and tied, the gear wire and the thread can be coated with thick CA or epoxy adhesive for a solid mount.

Former F-3 requires 1/16-inch doublers across the top and bottom for stiffness. When it is installed, they should face the rear.

Fuselage assembly starts with gluing the main fuselage doublers to the fuselage sides, also using thick CA. Make sure that you make a right and left side! These doublers face the inside of the fuselage. After they are set up and dry, place the fuselage sides over the side view of the plans and mark the locations of all of the formers and stiffeners using a soft lead pencil.

The fronts of the fuselage doublers are angled down to provide downthrust for the motor. Using a straightedge as a guide, trim 1/32 inch from the front of the right side fuselage doubler to allow for the required right thrust. Install all of the vertical fuselage stiffeners in locations T-4 through T-6, but wait until the fuselage box is assembled to add the stiffeners and gussets to F-1, F-2, and F-3.

Pin the fuselage sides upside down over the top view on the plans with the doublers to the inside. Make sure both sides are perpendicular to the work surface. Now install former F-2 (the landing gear legs will be sticking up) and former F-3, using CA adhesive. Make sure that they are installed squarely and stay that way until they dry.

Epoxy the F-1 motor mount in place using pins or clamps to keep it against the front of the doublers until the epoxy cures. Be sure the right- and downthrust angles are maintained! Neatness counts to later allow easy installation of the rear triangular gussets.

After the three formers are dry, unpin the fuselage box and install the top and bottom crosspieces, using the top view of the plans as a guide for cutting them. As each piece is glued in place to the back side of its respective stiffener, keep checking the fuselage to make sure it remains square, and adjust as necessary.

After the crosspieces at station F-6 are glued into position, pull the tail together and use a drop of glue to tack it in place until you can be sure it is square and not pulled to one side or the other. When you are satisfied, permanently glue it together.

The turtledeck formers T-3 through T-6 can now be added squarely on the top fuselage crosspieces. Be sure they remain vertical as they dry. Glue a scrap of 1/16-inch balsa to the back of the T-3/F-3 joint with the grain running vertically. The turtledeck side panels are cut from soft 1/16-inch wood, tapering the bottom of each panel so that it fits snugly along the fuselage side. Test-fit it in place and sand as needed.

Mark a spot approximately 1/8 inch above formers T-3 and T-6 then place a straightedge over the two spots to cut each side panel to a long, triangular shape. First glue each side panel to the turtledeck formers. Keep the bottom of each side panel snug against the fuselage side then glue the fuselage/turtledeck joint from the inside of the fuselage box.

After both side panels are in place, sand the top of the panels flush with the turtledeck formers and cover the top with a triangular piece of balsa. Sand the top piece until it conforms to the side panels and round the top of the turtledeck. The goal is to make all seams as undetectable as possible.

The battery hatch is made from 3/16-inch balsa. I found it useful to make the hatch full length from the motor mount back to the wing’s LE, tapering it as shown. When you are satisfied with the shape, cut the hatch into two pieces 5/8 inch behind the motor mount and glue the smaller piece in place as the front hatch anchor.

Make a 1/32-inch plywood anchor “tongue” and glue it to the bottom front of the hatch as shown in the photos. The hatch is anchored with 3/16-inch rare-earth magnets embedded in a 3/16 x 1/4-inch piece of medium-hard balsa and the bottom of the hatch.

Embed one of the magnets into the balsa piece flush with its top surface by drilling a small indentation and pressing the magnet into it, securing it with CA glue. Install that piece 1/2 inch forward of former F-2. Stack the second magnet directly on top of the embedded one. Now insert the hatch tongue under the front hatch anchor as far forward as it will go. Position the hatch as perfectly as possible, and press it down over the stacked magnets.

The magnet on top will make an indentation in the bottom of the hatch, providing an accurate location for embedding the second magnet. Drilling a small indentation and gluing the magnet in place, flush with the bottom of the hatch surface, will be an easy task. However, make sure you maintain the correct polarity with the second magnet as you glue it in place. The hatch needs to deliver a satisfying click when it’s closed, not pop up because of reversed polarity! Sand and taper the rear of the hatch as shown to fit over the wing’s LE.

Everything fits neatly into the fuselage. The Tactic TR624 receiver and the 8-amp ESC are both mounted to the fuselage sides with stick-on hook-and-loop material.

Add the battery platform, servo rails, and the two 9-gram servos while the bottom of the fuselage is still open and easily accessible. At this point, the motor can be mounted to former F-1 and the ESC attached. Drill holes for the wing mounting dowels and glue them in place. Use two #32 rubber bands on each side to hold the wing down.

The wire pushrods are .039 diameter lengths of music wire with Z-bends at one end. The other end fits into Du-Bro EZ Connectors mounted on the servo arms for adjustment. Poke the wires out through their respective openings, crossing them as they run from the servos out through the precut openings in the fuselage sides.

At this point, close the fuselage bottom using 1/16-inch cross-grained balsa from former F-3 forward, and 1/16-inch balsa running lengthwise from F-3 back. Note the air exit hole cut in the rear of the fuselage to provide adequate air flow over the ESC and other electrical components. The plywood tail skid can also be glued in place.

Tail Surfaces

The tail surfaces were presumably cut from medium 3/32-inch sheet balsa during the pre-kitting process. The stabilizer/elevator and the fin/rudder can now be separated using a straightedge. Join the two elevator parts on top of the plans, epoxying a wooden dowel in place as the joiner.

Sand the elevator LE and the rudder LE to a 45° chisel shape. Keep the stabilizer and fin TEs square, and round all of the other tail component edges. They can now be sealed with two or three coats of nitrate or Sig Lite-Coat dope thinned 50% and sanded gently between coats. The dope will provide moisture protection. After the second coat dries, the surfaces can be hinged using 1/2-inch 3M Blenderm tape.

Hinging the tail surfaces with Blenderm can best be done by starting with the fin and rudder and cutting a strip of tape slightly shorter than the full length of the two pieces being hinged. Lay the two pieces flat with the hinge edges touching (but not jammed together) and the chiseled side down. Center the piece of tape you cut lengthwise (in the same direction as the wood grain) to the pieces and press it down. Now turn the joined pieces over and fold them flat against each other, keeping the hinge edges straight.

Cut two more 1-inch lengths of tape and place them horizontally across the grain of the folded pieces close to each end then unfold the joined unit. You should have free movement in both directions using this method. Hinge the stabilizer/elevator joints using the same technique.

Finishing

Final sand the fuselage and wing with 300-grit wet or dry sandpaper, and apply two or three thinned coats of dope to both, sanding gently between coats. The prototype has tissue trim attached by bleeding thinner through the tissue and sealing it with a final coat of thinned dope. Don’t be tempted to load up the airplane with colored dope. The weight gain would be unacceptable.

Use two #32 rubber bands on each side to hold the wing in position and test-fit the stabilizer to its platform, sanding the platform if necessary to make sure it is squarely aligned from both the front and top view. When it’s satisfactory, glue it in place. After it dries, sand two pieces of 1/8-inch square balsa to a triangular shape and reinforce the stabilizer/fuselage joint as shown on the plans. Now thread the elevator control horn onto its pushrod and locate it as shown on the hinge line.

The pushrods for both control surfaces should first be threaded onto the horns. The horns should be glued with CA into predrilled holes in the rudder and elevator surfaces. Excess horn posts protruding through to the top side can simply be clipped off.

I used Du-Bro micro control horns on both the elevator and rudder by predrilling the twin mounting post holes and threading the pushrods onto the horns. You can glue the horns in place with CA and let them dry then cut off the portion of the posts that stick up above the wood.

Treat the rudder in the same manner as the elevator, making sure it is vertical and squarely in line with the centerline of the fuselage. Hold it in place until the glue dries, then carve, sand, and add the tapered scrap blocks to either side for additional support.

At that point, installing the receiver and adding the wheels and windshield are all that’s left to be done. Balance the airplane as shown by shifting the battery as required. On the prototype, the battery was placed directly against the front of former F-2, which proved to be perfect. I hope you will not need additional weight to balance your Old School.

The cockpit area is dressed out with a card stock profile pilot figure that was obtained online and a windscreen cut and bent from lightweight celluloid and anchored with Pacer 560 canopy glue. The simulated cockpit opening is black tissue doped in place.

Flying

The first flights can be rise-off-ground because the RimFire 250 motor has plenty of power for a model of this size. Takeoffs are smooth by adding power gradually and a shade of rudder control to keep it straight on the runway.

The Old School is an enjoyable model to fly that is friendly to beginner builders.

It is a predictable and stable flier, both at low speed and at the top end of the throttle. You can expect flights of 6 to 8 minutes or more flying at mid-throttle. Landing the airplane is easy, even in moderate breezes. Simply throttle back and let the Jedelsky wing do its work. It will slow down almost to a hover when faced into the wind and will land within 5 or 6 feet.

A three-quarter rear view shows the completed model before its maiden flight.

I hope you will enjoy the Old School as much as I did designing this special airplane for new builders.

—Larry Kruse
aircats@att.net

Sources:

Hobbico/Tower Hobbies
(800) 637-6050
www.towerhobbies.com

Du-Bro
(800) 848-9411
www.dubro.com

Sig Manufacturing
(641) 623-5154
www.sigmfg.com

APC Propellers
(530) 661-0399
www.apcprop.com

Old School: Plan #1106

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Old School: Plan #1106

Click the button below to purchase this plan.
(Your transaction will be processed securely with PayPal.)

A shipping fee will be applied at checkout.
You will have the opportunity to review your order, including shipping, before finalizing.

Old School: Plan #1106

Click the button below to purchase this plan.
(Your transaction will be processed securely with PayPal.)

A shipping fee will be applied at checkout.
You will have the opportunity to review your order, including shipping, before finalizing.

Written by Jay Smith
As seen in the April 2018 issue of Model Aviation.