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 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 Fitz Walker
An economical, gas-powered or quiet electric sport model
Product Review
As seen in the May 2018 issue of Model Aviation.

Specifications

Model type: Sport
Skill level: Intermediate
Wingspan: 69 inches
Wing area: 640 square inches
Length: 51 inches
Wing loading: 25 ounces per square foot
Weight: 7 to 8 pounds
Power system: 10cc two- or four-stroke gas/petrol engine or equivalent electric motor system
Radio: Full-range, six-plus-channel transmitter and receiver; seven standard-size servos
Construction: Balsa and plywood
Price: $249.99

Test-Model Details

Engine used: Evolution 10GX
Battery: 2S 2,000 to 4,000 mAh LiPo for receiver and engine ignition
Propeller: APC 12 x 6
Receiver: Spektrum AR7350
Servos: Seven Spektrum A6110 HV
Radio: Spektrum DX9
Weight (ready to fly):7 pounds, 8 ounces
Flight duration: 10 to 15 minutes

Pluses

• Great flying qualities with attractive scalelike looks.
• Easy access to interior components.
• Well built with quick and easy assembly.

Minuses

• Stock wheels are somewhat bouncy on pavement.
• Several minor errors in instruction manual.

Bonus Video

Product Review

I admit that I’m primarily an electric model flier. Making the transition from glow to electric some years ago, it is now my comfort zone.

I like to try new things, if not simply to gain more knowledge and experience. Although I’ve spent much time running glow engines of all types throughout my modeling years, I’ve never tried a gasoline-powered model engine.

Usually reserved for large models, there has been a movement to manufacture gas engines in increasingly smaller sizes. Add the bonus of using very inexpensive automotive fuel, and it is easy to see why small gas engines are popular with fliers who like their airplanes to make some noise!

Following in Hangar 9’s line of 108- and 53-inch wingspan Valiants is this midsize 69-inch wingspan ARF. Constructed of traditional balsa and plywood, this 10cc-powered Valiant continues the company’s line of scalelike high-wing sport airplanes.

Most of the parts were well packed and individually wrapped in plastic. Parts for both electric and gas versions are included with motor mounts and a fuel tank supplied for the latter. Most of the hardware you will need is already in the box.

The Valiant kit is complete and well supplied with hardware.

The 91-page manual is in several languages and includes black and white assembly photos for every step. There should be no guesswork in assembly.

The model is covered with iron-on film, and if you look closely in the manual, there are part number references for matching UltraCote replacement colors. The attractive red and white motif has accompanying high-visibility stripes on the bottom of the wing and tail.

There was some slightly loose covering on the ailerons and flaps, but that was quickly rectified with a heat gun. Nearly all of the decals are preapplied at the factory.

Assembly

Assembly starts with the flaps, which are offset hinged via point hinges. The hinge holes are predrilled, so installation is easy. Ailerons and tail surfaces are attached using CA hinges with pre-slotted holes.

The large flaps are offset hinged.

All of the servos in the wing are attached to removable servo plates that screw into place. You will, however, need to drill some mounting holes with a 1/16-inch drill bit. Pull strings are preinstalled inside the wing for easy routing of servo wires. The kit also includes heavy-duty metal clevises for the control surfaces and prebent control rods. The wing halves use an aluminum tube for a spar and nylon thumbscrews for attaching them to the fuselage.

Anyone who has ever built an ARF will find no surprises when installing the tail surfaces. After trimming the covering, epoxy is used to glue everything together. The horizontal tail alignment was perfectly parallel with the wing out of the box.

The tail wheel assembly is a simple, but nice, affair. It all comes prebent and it takes only a bit of epoxy into the rudder and a couple of screws to mount the pivot plate onto the bottom of the fuselage. This was where I noticed a conversion error in the manual. The manual says to use a 2 mm or 5/32-inch drill bit. It should actually be 5/64 inch, otherwise you will drill a hole that is too big.

You are conveniently supplied with a choice of two tail wheel types: foam for quiet operations off of a paved runway, and a rubber one for grass operations. This is a nice, thoughtful touch. Another one is that all of the control surfaces are predrilled for the plastic control horn mounting screws, which saves time.

Next it’s on to the business end of the model. The fuselage has two access hatches: a screwed down top hatch between the wing halves and a magnetic battery/fuel tank hatch that is integrated with the windshield.

Two hatches allow easy access to the Valiant’s fuel tank and radio gear.

This is where the manual splits off depending on whether you use electric or gas power. For those such as I who are using a gas engine, there is an extremely helpful wood plate that keys into the firewall and functions as a drill template for the included motor mounts. It is practically foolproof—even for the exceptionally gifted fools.

The recommended fuel powerplant is the Evolution 10GX 10cc gas engine. This stylish engine has a pumped carburetor, ABC-type construction, and for all practical purposes, looks like a glow engine. Only the protruding spark plug and ignition sensor wire betray its thirst for petrol instead of methanol.

Because it was my first gas engine, I was enthralled not only by the motor, but its accompanying electronic ignition box. This box is fairly small and lightweight and even includes an rpm sensor output for those with telemetry in their Spektrum radios.

The manual details how to mount the engine and its electronic ignition box, which I had no problem finding room for. My only concern was that the truncated firewall did not leave much room for error when drilling the lower two motor mount screw holes. I would have liked a little more wood there.

A handy drill template makes mounting the engine easy. The Evolution engine fits perfectly inverted and awaits cowl trimming.

The prepainted fiberglass cowl has a nice, glossy finish and was easy to cut and trim for the muffler. You must use an exhaust header extension in order to move the muffler away from the side of the cowl. Attaching the muffler with the cowl on is tricky, but with patience, it all comes together.

To be able to prime the inverted engine, I elected to make a small cutout in the lower front of the cowl so that I can reach the carburetor intake with my finger. This should also help improve cooling.

I left the landing gear assembly for last because it is easier to build the model when it is not actively trying to roll itself off of the workbench while you work on it. No surprises here, and I liked the way the fiberglass wheel pants attached to the metal landing gear. There are only two bolts that screw into blind nuts inside the pants. It is simple with little chance of the pants rotating out of position. The included main wheels are foam rubber.

The controls were set up per the instructions, where I noticed another typo in the manual where it states to set the maximum flap deflection to 150 mm. Somehow a “1” creeped in. I’m pretty sure Hangar 9 meant 50 mm because it would be impossible to achieve a nearly 6-inch flap deflection.

I should also note that the Evolution ignition module, Spektrum receiver, and servos all can operate on 6- to 8-volt power. This allows you to use two-cell LiPo or LiFeO4 batteries without needing a voltage regulator. I used a two-cell LiPo battery. This is my first time using such a setup and I found it convenient. Because everything runs off of one battery, at least a 2,000 mAh battery is recommended.

Breaking In

The first step with flying any fuel-powered model is breaking in the engine. I found premixed gasoline at a local hobby store but I needed to add some additional two-stroke oil in order to comply with the engine’s 20:1 oil requirement. The manual recommends using an electric starter to initially start the new engine.

Out of curiosity, I decided to see if I could hand start it (with a chicken stick). After a couple of dozen flips, the Evolution engine sprang to life with a rich, sputtery, but consistent growl.

After a couple of tanks of fuel and some leaning of the high- and low-speed needle valves, the engine actually became pretty easy to hand start. I noted that the exhaust residue was dirty, but that is apparently typical of this engine until it is fully broken in.

Flying

Ground tracking on takeoff is good with only a little rudder input needed to keep the aircraft straight. Expect the model to become airborne quickly, even if you don’t use flaps. Drop the flaps slightly and the model is flying by the time the engine has finished revving up. The recommended control rates were a good starting point, with the low rates being mild and high rates fairly lively, but not overly so.

I particularly noted that the aileron response was light to the touch without being twitchy. The power with the 12 x 6 APC propeller was good with a decent vertical ascent despite the engine being slightly rich.

With a couple of clicks of trim to get things straight, I proceeded to get a feel for the Valiant’s aerobatic capability. Rolls were nice and axial, whether on high- or low-rate settings. Loops were equally graceful, although I preferred to do them on high rates. Snap rolls induced a wonderful gyration that wasn’t blisteringly fast, but strangely hypnotic. The same goes for spins. Not pretentious—just a good, honest spin. This airplane really likes to be thrown around.

Rudder authority is better than the stock control setup would suggest, with plenty of power for hammerheads and even sustained knife-edge flight in either direction. The semisymmetrical airfoiled wing flies inverted wonderfully with only a little down-elevator needed to keep things level.

I felt quite at ease making low inverted passes over the runway. No one would call the Valiant a racing machine, but it scoots along nicely at full power. However, slow speeds are where it really shines. Those big, offset flaps generate a lot of lift and slow the airplane to a crawl when they are fully lowered. There is some ballooning when they are initially deployed, but if you feed them in slowly at low airspeeds, pitch-up is pretty tame.

I suggest adding some down-trim mix to further tame it. Stalls with or without flaps are extremely mild and will build a pilot’s confidence. There is no need to be afraid of jerking around at low speeds.

Landings are a nonissue, although be prepared for a surprisingly long glide if you don’t use the flaps. Those who don’t back off the power early in the pattern will need to be prepared to go around as the Valiant glides down the whole length of the runway. I recommend using the flaps on calmer days because they help bleed off speed, even on steep approaches. Right at the flair, the elevator loses some of its authority on low rates, so I prefer to land on high rates.

Summary

The Hangar 9 Valiant is a fantastic model for almost all skill levels. Newer pilots should be able to easily handle it on low rates, while more experienced pilots will appreciate its aerobatics capability. Despite being a non-scale airplane, it actually presents in a very scalelike manner and will surely turn heads at the flying field.

The Evolution 10GX has been a fine-running engine with no dead-stick landings and a reliable idle. The power is more than adequate while being fuel efficient. I found the Valiant to be a perfect airframe for my first foray into gasoline-powered models.

—Fitz Walker
flying_fitz@yahoo.com

Manufacturer/Distributor:

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

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

Sources:

Spektrum
(800) 338-4639
www.spektrumrc.com
Evolution Engines
(800) 338-4639
www.evolutionengines.com

Written by Greg Gimlick
Start down the RC path in style
Product Review
As seen in the May 2018 issue of Model Aviation.

The Carbon Cub S+ is capable of being flown by people with varying skill levels. Thanks to its large tires, it is capable of operating from flying sites with grass, dirt, or pavement.

Bonus Video

Specifications

Model type: GPS-equipped park flyer
Skill level: Beginner to expert
Wingspan: 51 inches
Wing area: 418 square inches
Length: 34 inches
Weight: 35.6 ounces
Wing loading: 12.28 ounces per square foot
Power system: ParkZone 480 brushless outrunner motor 960 Kv (included); ParkZone 18-amp brushless ESC (included); ParkZone 9 x 6 propeller (included); E-flite 1,300 mAh 3S 20C LiPo battery (included)
Radio: Spektrum DXe DSMX transmitter; Spektrum DSMX serial receiver; Spektrum flight controller (all included)
Construction: EPO foam
Needed to complete: Nothing
Flight duration: 5 to 7 minutes
Price: $219.99

Pluses

• Exclusive SAFE Plus GPS-enabled drone technology.
• AutoLand, Holding Pattern, and Virtual Fence functions.
• Beginner, Intermediate, and Experienced flight modes.
• EPO foam airframe with fully painted scale trim scheme.
• Tundra tires.
• Optional flaps (requires a seven-plus-channel programmable transmitter).
• Optional floats are available.

Product Review

Full disclosure: I love Cubs. I love all variants of them and am not ashamed to say so! This version did not disappoint when I opened the box. The Carbon Cub color scheme is a thing of beauty and this little foam gem looked well done. Everything was neatly packed and protected with nothing left to buy.

Relatively few pieces come with the RTF package; however, everything required for flight is included.

As always, read the manual thoroughly ahead of time to familiarize yourself with the assembly process and radio programming. The RTF version comes with a DXe transmitter set up for the various GPS functions, but there are instructions for other Spektrum radios. If you want to add the optional flaps, you’ll need a radio capable of seven channels.

Assembly begins by removing the propeller, allowing you to perform control checks without fear of injury. The landing gear is next and consists of putting the wheel collars and wheels on the gear legs. After it is complete, it slides into a fuselage receptacle and is held in place with two retaining plates. These are labeled left and right, so pay attention.

The landing gear has snap-on fairings and formed legs with tundra tires. The gear legs slide into a plastic recess and are retained with tabs and screws.

The tail feathers slide together with plastic pins and screws. Everything is dry fit and secured with the screws. Don’t tighten the rudder hinge screw too much or it will bind. The clevises attach to the installed horns and are retained with rubber keepers.

The tail pieces slide together with alignment pins and are held in place with screws.

The main wing arrives with channels cut into the top surface to accept mounting tape and vortex generators. Double-check the diagrams in the manual to ensure proper orientation. When complete, slip the joiner tube in place, slide the wings together, and use the plastic top piece to hold it all together. That piece provides the four retaining screw locations. Wing struts provide an extra measure of security for extreme maneuvers.

The last step is securing the battery in the compartment under the fuselage. There is plenty of room for various sizes of packs. The provided 1,300 mAh LiPo battery pack can be adjusted to acquire the proper center of gravity (CG). If you use a larger battery pack, there is room for that too.

The bottom view of the airplane shows the battery compartment and wing struts.

Special Features

SAFE Plus: There is an amazing amount of technology in this package. The Carbon Cub S+ offers three flight modes with varying levels of stabilization and limits to the pitch and roll angle.

Virtual Fence Mode and GPS: The GPS module allows a pilot to establish a “home” position. The flight controller Using this position, the flight controller establishes a preprogrammed geo-fence and automatically turns the aircraft if the pilot flies out too far. When the airplane is back within the “fence,” it wags the wings and returns control to the pilot.

The Carbon Cub S+ uses a GPS module and receiver that can be seen here from the top of the fuselage.

The Virtual Fence feature works in all SAFE Plus flight modes when the GPS function is active. Four variations of the Virtual Fence mode are selectable from the transmitter during initialization.

After a Virtual Fence mode has been chosen, the aircraft will remember that mode until another mode is chosen. There is no need to select it each time after you determine the mode appropriate to your area.

If you don’t want the fence feature at all, simply disable it at startup, but even better, you can turn it off during a flight by mashing the bind button and cycling the mode switch three times.

Beginner’s Bonanza!

This airplane offers beginners many options to help them learn to fly when help isn’t nearby. Even if there is help available, it offers options that help build confidence. If the airplane begins to get too far away, the geo-fence will bring it back.

If a pilot becomes slightly overwhelmed and needs a minute to gather his or her wits, by simply pushing the holding pattern button, the airplane will orbit over the home position on its own. When a pilot is ready to resume flying, merely push the button and take control back.

The biggest fear comes when it’s time to land and the new pilot is panicked about damaging the new model. If stress overcomes you, just hit AutoLand and relax while it brings itself in.

Compass Calibration:

If you’ve used GPS-enabled aircraft before, this is something you’re probably already used to doing. This is a simple procedure you should follow before flying at any new location. It’s fully described in the manual.

Control Throws and CG

I set the CG at the recommended 62 mm to 68 mm and adjusted the battery position to achieve that. Control throws were preset and dual rates are suggested at 100% and 70% (also preset in the RTF version).

Flying

Test-flight day brought a balmy 45° and 10 to 15 mph wind gusting to 25. Not ideal for a high-wing, 35-ounce airplane, but you “dance with the one who brung ya.” What these conditions did do was provide a rugged test of all of the airplane’s features. It didn’t disappoint!

After going through the compass calibration and setting the home position, when the GPS signaled that it was locked in, I pointed it into the wind and off it went. Climbout was strong enough despite the stout wind and it handled a slight crosswind well. Turning downwind saw the Cub imitate rocket acceleration, but it was still controllable.

I wanted more control authority in these conditions than Beginner Mode allowed, so I flipped the flight mode to Intermediate and it felt better. A couple of patterns to get the feel of how much stabilization there was in this mode left me confident in how well it could handle adverse conditions.

I flipped it to Experienced Mode and that put the full aerobatic envelope at my disposal. The little airplane will loop, roll, fly inverted, and even perform respectable knife-edge flight. I flew around trying all sorts of maneuvers and continued to be surprised at how well it handled the conditions.

When it was time to land, I returned to Intermediate Mode and the wind nearly stopped the Cub on final approach. It took plenty of power to drive it to the ground and I wanted more elevator, but that was easily accomplished by using Experienced Mode on the next flight.

Under normal flying conditions, the Beginner and Intermediate modes offer plenty of control authority. Tracking is excellent on the ground and in the air. Stalls are uneventful and even when the wind blew it over onto its back during an intentional stall, it was easily recovered.

Testing the Special Features

This was the fun part and certainly an eye-opener for someone who was not used to seeing an airplane do things that this Carbon Cub S+ did. I started by testing the Virtual Fence limit, which was set for the default value of 500 feet.

I flew straight and level until suddenly the airplane made a 180° turn all by itself—and I mean right now! It turned back toward the center of the field and flew straight and level for a few seconds then wagged its wings to let me know it was ready for me to resume control. I repeated this several times just because it was so effective and impressive. What a great feature … but wait, there’s more.

Next up was the self-leveling feature in Beginner Mode. Nothing to do here, but release the controls and watch as it recovered to a level attitude. I began in Experienced Mode and put it in a spin, then flipped to Beginner Mode and released the sticks. It quickly stabilized and was ready for me to resume control. Time and time again, it did a great job.

After playing with that function, I tried the holding pattern. If you find you need a break, simply hit the bind button and release it. The airplane enters an orbit at altitude around the home point. The Cub simply flew a circle overhead until I pushed the button again and took control. This offers a great break for a new pilot who needs a moment to gather his or her wits. Even with a strong crosswind, it adjusted to remain above the field.

Finally, the time came to try the AutoLand function. I began on the downwind side, held the bind button for 3 seconds, and then released the controls. The airplane continued a pattern to final and descended to the home point. It allowed for small corrections to avoid any obstacles and for throttle to adjust the descent.

I did this the first two times before finally heading across the field toward the pits and hitting it again. This time it turned downwind, completed the pattern, and started its final approach somewhat diagonally across the field. I told my friend Wayne, “This thing is confused with this wind.”

I watched it continue until it suddenly did a 360° circle, realigning itself with the runway and completing the approach and landing. I hadn’t touched a thing! I never touched a thing all the way to the ground when it stopped right in front of us. Amazing! We couldn’t believe it did that well in these conditions.

Wayne had to try it for himself and sure enough, he had the same result. When it wasn’t well aligned, it would do a circle, align itself with the runway, touch down in front of us, and roll to a stop. It didn’t matter that our throttle was still halfway; it had full control and did what magic it was programmed to do.

Conclusion

I’ve been around a while and I will admit to being somewhat jaded, but this slapped it right out of me. What a gem of a job the people at Horizon Hobby have done bringing us this bundle of technology. Not only does it work better than I could have hoped for, but it brings it all to the table at a price point that’s hard to believe.

This is a great first airplane for someone, but it’s a great airplane for anyone. Beginners to experts will enjoy this model’s characteristics and features. Having a great airplane to learn on is fun, and having one that is a cool little scale aircraft is even better. Do I like it? Oh yeah, I love it!

Since the initial flights, I’ve added the optional flap servo and bound it to my Spektrum DX9 so that I could expand the flight envelope. I have increased elevator and rudder throws just to increase the aerobatic capability, but the stock Horizon Hobby Carbon Cub S+ is perfectly capable of doing more than any beginner will want to try.

Flying from grass is not a problem thanks to the large tundra tires.

—Greg Gimlick
maelectrics@gimlick.com

Manufacturer/Distributor:

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

Sources:

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

Written by Terry Dunn
Ready for long, relaxing flights?
Product Review
As seen in the May 2018 issue of Model Aviation.

Specifications

Type: ARF electric glider
Wingspan: 118 inches
Wing area: 1,050 square inches
Length: 49 inches
Radio: Futaba 14SG 2.4 GHz transmitter; Futaba R617FS receiver; Futaba S3010 high-torque ball bearing servo; Futaba S3154 digital micro servo
Components Electric power system; three-
needed to complete: plus-channel radio with one standard servo and one micro servo; basic assembly tools
Minimum flying area: Club field
Price: $219.99
Power system: Great Planes RimFire .32 brushless motor; 13.5 x 7 folding propeller (included); Castle Creations Phoenix Edge Lite 75 ESC; Flight Power FP50 4S 3,600 50C LiPo battery
Power output: 53.8 amps; 785 watts
Power loading: 168 watts per pound
Flying weight: 4.7 pounds
Wing loading: 10.2 ounces per square foot
Duration: How long have you got?

Pluses

• Great styling.
• Super gliding performance.
• Powerful climbs.

Minuses

• Some building challenges.
• Few energy-management tools.

Bonus Video

Product Review

With its classic, curvy styling and distinctive wing profile, the Bird of Time is one of the most recognizable RC models around. But this airplane is more than just a pretty face. The Bird of Time was originally designed as a competition glider, which explains its low-drag fuselage, thin airfoil, and full-flying elevator.

Throughout the years, countless Bird of Time models have been built from plans, kits, and ARFs. Many of those airplanes were modified to use an electric motor and folding propeller on the nose.

Electric sailplane fans can now put away their cutting wheels and sanding blocks. Great Planes recently unveiled the Bird of Time EP. This variant of the company’s Bird of Time ARF is factory equipped for electric power.

The Bird of Time EP features a fiberglass fuselage with a firewall that accepts a brushless outrunner motor. A folding propeller with an integrated spinner is included. You’ll have to supply the motor, ESC, and battery to round out the power system.

The aircraft’s characteristic wing has a huge span of 118 inches. It is a built-up balsa and hardwood structure that breaks down into three pieces. The elevator and rudder are built up and factory covered as well. Despite the model’s substantial size, it requires only a three-plus-channel radio with two servos.

The Bird of Time EP is a simple, but elegant powered glider that is perfect for enjoying relaxing flights on calm-weather days.

Inspecting the Bird of Time EP

My inspection of the kit was mostly positive, but I did find some minor workmanship-related blemishes. I thought that the fuselage was well molded, nicely painted, and appropriately sturdy. The wing panels felt lightweight, yet strong. A few areas in the MonoKote covering had poorly adhered seams. I was able to tidy them up with my covering iron. I also spotted a few “pimples” in the covering which hinted that the underlying balsa framework had not been adequately sanded.

This kit includes two manuals. One is for the pure glider version of this ARF. The other is an addendum that notes specific steps to add or delete for the powered variant. It’s a bit cumbersome to seesaw between the two manuals. After you factor in the additional online-only addendum, things can get a little clumsy. A single EP-specific manual would be a helpful update.

This is not the kind of ARF that builds in a single afternoon. Although there is not much to do, the assembly steps often demand precise, careful actions. I don’t think that any of the tasks are challenging for experienced modelers. You just want to give yourself plenty of time to complete them accurately.

The Bird of Time EP includes prefabricated balsa wing panels and a fiberglass fuselage that is ready to accept a brushless power system.

Assembling the Bird of Time EP

The first assembly step is to construct two dihedral braces that join the outer wing panels to the center section. Each of these beefy components is made by sandwiching two plywood parts between thick aluminum plates. Although it isn’t mentioned in the manuals, the plywood parts in my kit were two different thicknesses. Make sure that each brace gets one thick and one thin plywood piece.

As suggested in the manual, I used 6-minute epoxy when laminating the dihedral braces. I think that the additional working time of 15- or 30-minute epoxy would have been helpful. I used several clamps to hold the parts firmly in place until the epoxy cured.

I chose to permanently glue the dihedral braces to the center wing panel. I also rounded the exposed tips of the antirotation pins to ease panel alignment during field assembly.

My assembled wing has some minor gaps at the panel joints, but they are nothing to be concerned about. I used several pieces of clear Scotch tape to hold the panels together.

Stout dihedral braces are constructed by laminating aluminum and plywood components with epoxy. Take your time to ensure that the parts are properly aligned.

A Futaba S3010 high-torque standard servo fits perfectly in the servo tray beneath the wing saddle. It actuates the rudder via a long pushrod. The full-flying elevator is actuated by a Futaba S3154 digital micro servo located at the base of the vertical stabilizer. Although small, the S3154 has plenty of torque for this application.

The full-flying elevator is actuated by a digital micro servo, located at the base of the vertical stabilizer.

The manual outlines a combination of hardwood blocks, servo tape, and screws to hold the elevator servo in place. I decided to forego that method. After scuffing and cleaning the mounting area and servo case, I glued the servo directly to the airframe with 6-minute epoxy.

My Bird of Time EP is powered by a RimFire .32 brushless motor, Castle Creations Phoenix Edge Lite 75 ESC, and a Flight Power four-cell 3,600 mAh LiPo battery. Space in the motor/battery compartment is tight, so I planned my equipment layout to make the best use of the available space. I also wanted to get the battery as far forward as possible to avoid any need for nose weight.

I mounted the RimFire .32 to the firewall with the motor wires emerging toward the bottom of the fuselage. The ESC is mounted at the rear of the battery tray. In fact, the ESC capacitors protrude rearward under the servo tray. Motor wires from the ESC are routed beneath the battery tray.

The battery leads from the ESC emerge upward though the servo tray and forward into the battery compartment. To fit the Deans Ultra Plug through the servo tray, I had to slightly enlarge the forward lightening hole. The battery is placed just forward of the ESC. I replaced the kit’s two-piece hook-and-loop strap with a single length of double-sided hook-and-loop tape.

Using the arrangement described, my model did not require any nose weight to balance at the suggested center of gravity (CG). I actually have some latitude with which to adjust the CG slightly forward or aft. I have to be careful that I do not place the battery against the rotating portion of the motor.

The author was able to arrange all of the necessary components in the battery bay to fit cleanly and avoid adding any nose weight.

The kit includes a 13.5 x 7 folding propeller that has an integrated spinner and 5 mm propeller adapter. This assembly fits the motor shaft perfectly and blends with the shape of the fuselage. I made sure to balance the propeller before installing it on the model.

I noticed a significant gap between the spinner’s backplate and the firewall when the propeller adapter was fully seated. Shortening the motor shaft was not a solution because the pan-head screws holding the motor to the firewall would have interfered with the spinner. I decided to fill the gap with a ring cut from a scrap piece of sheet foam. I glued the ring to the firewall using Foam-Tac contact adhesive.

The gap between the spinner and firewall was filled by adding a ring made of thin foam sheet.

The fuselage has air inlets on either side of the motor, but no exit holes. Cooling has not been an issue while flying in winter. I plan to cut out an exit hole behind the wing mount to ensure that the electronics stay cool during the summer.

I connected the servos and ESC to a Futaba R617FS receiver linked to my 14SG transmitter. With only three channels, radio setup is a snap. I had to expand the elevator travel to 130% to get the suggested high-rate movement. It is necessary to activate the brake function on the ESC to halt the propeller and allow the blades to fold back while gliding.

The radio bay beneath the wing saddle houses only the rudder servo and receiver.

Flying the Bird of Time EP

Although the Bird of Time EP is a large model, field assembly is simple. The wing panels slide together easily and there are no servo leads to worry about. Two bolts fasten the completed wing to the fuselage. There is also ample access to the battery compartment. All you have to do is slide the canopy forward to release the attachment pins.

A hand launch gets the Bird of Time EP airborne. The power system generates plenty of thrust, so there is no need for full throttle or a Hail Mary throw when launching. I typically use approximately half throttle and give the airplane a horizontal toss into the wind. There’s nothing to it.

The manual mentions that the airplane will tend to pitch up under power. That is definitely true! If you launch with heavy throttle, you might find that the Bird of Time EP has gone vertical before you can even get your hands back on the transmitter. That’s okay because the airplane will continue to climb this way if you want it to.

I have considered adding a throttle/elevator mix to tune out this behavior. However, I think it is easy to correct with stick inputs now that I know what to expect.

Depending on your departure angle, the Bird of Time EP could get to gliding altitude within a few seconds. You won’t have any trouble spotting that big wing, but the solid white underside is sometimes difficult to orient. After a few flights, I added three stripes to the bottom of the port wing using 2-inch-wide colored packing tape. This quick tweak really helped improve visibility.

I’ve been flying the Bird of Time EP in winter conditions—often in below-freezing temperatures. Although there might not be many thermals around, the airplane still maintains altitude well. The glide is flat and flights are long. Each battery charge is good for numerous climbs to altitude.

The full-flying elevator does not have much throw, but it provides plenty of pitch authority. The rudder is huge and effective. I set up my model with the suggested dual rates. I tend to fly almost exclusively with high rates. The control response is positive, but not twitchy.

The motor is not only for climbing. You can dial back the power and cruise around on the deck. The Bird of Time EP behaves like an overgrown park flyer.

I’ve done a few loops with the Bird of Time EP. That is the extent of the aerobatics that I will attempt. It might be capable of more, but this airplane is in its element with a smooth and gentle touch on the sticks.

The polyhedral wing makes for stable flight. I’ve done circuits above the field using nothing but rudder trim for control! The flip side to this is that the airplane is somewhat sensitive to wind. You’ll want to save this one for days with single-digit wind speeds.

When it’s time to land, you will find out just how aerodynamically clean this design is. It simply does not want to stop flying. There are no spoilers or flaps to help bleed off energy, nor are there ailerons to pair with the rudder for a sideslip. Be sure to set up a long approach.

I’ve found that the propeller can be used as an air brake to help manage energy. It just requires precise inputs. With my setup, one click of throttle kicks out the propeller blades and slows the airplane, but two clicks of throttle produce no obvious effects. The airplane climbs with three clicks!

The rudder and elevator remain effective throughout the landing. Achieving a smooth, sliding touchdown poses no challenges. A protrusion built into the bottom of the vertical stabilizer helps protect the rudder during landing. Make a mental note to check the rudder and hinge every so often.

Final Approach

A large, powered glider such as the Bird of Time EP could seem intimidating to some pilots. Although this ARF does require attention to detail during the assembly, I think that most modelers will have no trouble completing it. The aircraft’s broad girth breaks down into manageable components that make transporting and storing it easy.

The stylish lines of the Bird of Time EP belie its fundamental simplicity. This model launches easily, and quickly reaches soaring altitude. It then transforms into a docile floater capable of long, relaxing flights.

—Terry Dunn
terrydunn74@gmail.com

Manufacturer/Distributor:

Tower Hobbies
(800) 637-4989
www.towerhobbies.com

Great Planes
(217) 398-8970
www.greatplanes.com

Sources:

Futaba
(217) 398-8970
www.futabarc.com

Beacon Adhesives
(914) 699-3400
www.foam-tac.com

Castle Creations
(913) 390-6939
home.castlecreations.com

Flight Power
(217) 398-8970
www.flightpowerbatteries.hobbico.com

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

For many of us, these early months of the year are cold, with wintery weather in full swing. This limits our flying time outside. Although it is a good time to get in some simulator practice, it is also a great time to tear down our helicopters for some maintenance.

Our helis talk to us when they fly, and we learn to listen to them and identify potential problems by the sounds they make. However, many problems can develop without giving us any kind of audible warning, and this is where regular maintenance can really pay off. Maintenance can be performed anytime, and is not limited to winter projects. The more opportunities you have to go through your heli setup, the better.

Disassembling our helis provides us the opportunity to inspect parts that we can’t typically see. I like to start with the main rotor head and pull the blade grips off to check all of the bearings. I inspect the bearings, making sure they are smooth, and clean and regrease the thrust bearings.

Depending on if the machine is electric or nitro powered, I’ll clean all of the parts before reassembling. Automotive brake cleaner is great for cleaning grease off of metal parts, but use it outside to avoid the fumes (don’t use it on plastic or rubber parts). If a head bolt has a buildup of stubborn threadlocker, I use an X-Acto blade to trim off the excess between the threads before cleaning it with brake cleaner. Have an ample supply of paper towels nearby when cleaning up. After the parts are cleaned and dried, I use threadlocker when reassembling the head.

Cleaning and regreasing the radial and thrust bearings from the main blade grips.

When I’m working on the main rotor, I pull the main shaft out with everything from the swash up in one shot. This makes working on the head slightly easier, but also gives me a chance to check the one-way bearing in the main gear.

One-way bearings in main gears/pulleys are typically spindle bearings. These have long rollers arrayed inside of the bearing, with a plastic cage holding it all in place. Occasionally, the plastic cage can develop cracks, which leads to the main shaft slipping on the bearing. I use a magnifying glass to check for any hairline cracks in the plastic, as well as possible cracks in the outer metal part of the bearing.

I clean the bearing (with paper towels, no brake cleaner), regrease with my favorite tube of grease, and reassemble. This is also an opportunity to get a good look at the main gear, and make sure it is not unevenly wearing, which can be a sign of a problem with the pinion gear mesh.

The most obvious sign of wear in belt drives is fraying along the sides. This is a good indication that the belt needs to be replaced. If there is any fine powder built up around the belt, it may be rubbing against something in the drivetrain. If you see a missing tooth on the belt, replace it.

Belt tension is critical, and the belt should be tight enough that it does not skip if you rotate the head while holding the tail. At the same time, you don’t want to tighten it too much. Your helicopter’s manual should give you some indication of how to tighten the belt.

Any dirt stuck in the gears will accelerate wear. Use an old toothbrush to clean these gears.

Inspecting a torque-tube drivetrain involves inspecting the bearings and gears. The common theme when inspecting these types of parts is to look for any unusual wear or cracks. The gears should have all of their teeth and not show any damage. The bearings should all be checked for smoothness, which can be accomplished by pressing on the inner race of the bearing while pushing in the opposite direction on the outer race and rotating it. You will typically be able to feel that notchy feeling if the bearing is damaged.

Gear mesh (backlash) is crucial to a smooth torque tube. The gears must be nestled together so that the teeth correctly engage, but not so tight that there is zero play and the gears are difficult to turn. A trick I use is to slide a piece of paper between the gears when I’m setting the backlash. This can work for the backlash of any gears, including the main gear and motor pinion.

The procedure for inspecting the tail is similar to checking the main rotor head. I pull the blade grips off to inspect the bearings, regrease the thrust bearings, and reassemble.

I make sure that the tail pitch slider slides freely without any binding, and if there is any binding a good place to start looking is the pitch links that connect the tail blade grips to the pitch slider. I review all of the ball links and bell cranks, checking to see if there is any excessive play or if there are cracks that require ball links to be replaced.

Dust next to a gear can be a sign of trouble. In this case, it was simply normal wear of the main gear.

I run a driver over all of the screws and bolts to ensure that none are coming loose, and finally I trace all of the wiring, looking for any signs of chafing or damage.

For nitro-powered helis, I check the motor for signs of leaking from the muffler, head, or backplate. I inspect the fuel lines and replace them if they look slightly worn. I also make sure that the clunk line in the main and header tanks looks good. If the heli will be setting for a while, I add after-run oil in the engine.

The maintenance process doesn’t take long, and it is worth it for the peace of mind I get from knowing that my fleet is in top shape and ready for the flying season. Occasionally, this type of maintenance has revealed a potential problem that I was able to fix. The less time I spend repairing crashed helicopters, the more time I spend flying.

Fly safely!

Sources:

International Radio Controlled Helicopter Association
www.ircha.org

New products that are Worth a Closer Look
Product review
As seen in the March 2018 issue of Model Aviation.

That’s quite a long name for such a small charger. This new charger from the people at Venom is perfect for everyone who flies smaller electrics that are powered by a single LiPo battery. Despite its small footprint, this charger is capable of charging up to four batteries at the same time. It has an internal power supply and can be powered with either AC or DC power.

It is 43/4 inches square by 2.1 inches high. This charger’s rugged plastic case is coated with a smooth, rubberized coating. To aid in cooling, Venom has included front and rear venting. The front vents are cut in the shape of the Venom logo and set off by red LED backlighting.

The top panel is where all of the magic happens. Four separate sets of connectors, an LED indicator, and a battery selector switch are located above the large LCD screen. Below the screen are four push buttons: Channel to select between the four outputs; Dec - and Inc + to adjust the charge rate; and Start/Stop, which does exactly as described.

Each of the inputs or channels is independently controlled and can charge either standard LiPo (3.7 volt) or LiHV (4.35 volt) batteries. These batteries can be plugged into one of four popular brands/styles of connectors, including the mCX (Picoblade 1.25mm), mCPX (JST-PH 2.0), JST, and Molex.

After it is powered up, the LCD indicator comes to life. As soon as you plug a battery into one of the connectors, the readout for that channel instantly displays the battery’s current voltage. If you want to charge, use the Channel button to move between the four channels, and the LED indicators will show the selected battery.

If you hold that same Channel button for a couple of seconds, charging mode begins. The charging rate can be adjusted with the Dec - and Inc + buttons. Each channel can charge at a rate between 0.1 amp and 1.0 amp, in increments of 0.1 amp. When ready to charge, push the Start/Stop button, and the readout will continually update with the battery’s voltage.

With this tiny size, a price of $59.99, and its four-port charging capability, Venom’s new Pro Quad Micro Charger is worth a closer look to keep your air force of microfliers charged and ready to fly.

Venom Group International
Tel.: (800) 705-0620
Website: www.venompower.com

Written by Greg Gimlick
Electrics
Column
As seen in the December 2016 issue of Model Aviation.

Happy holidays! As the season approaches, I wish all of you a very Merry Christmas and a great New Year. Thanks for your support of the column again this year and please continue to send suggestions, criticisms, etc.

It’s Time to Store Your Batteries

For many of you, flying season is over and it’s time to store your flight batteries. Even if you fly throughout the winter, chances are that you fly less frequently and you need to store your batteries longer than usual.

Whatever the voltage level is at when you choose to store them, be sure it’s not fully charged or fully discharged.

Arguments continue over the “proper” voltage level to use, but all agree it’s somewhere between full and empty. Most of my chargers use something around the 3.8-volt level and I’m good with that.

This pack shows perfect balance and voltage, but its physical damage makes it unsafe for continued use.

This is also a great time to put your batteries on your battery-management system and bring them down to or up to storage level while balancing.

Inspect your packs for damage or wear on the covering, wires, or connectors. If the connector is pitted and shows signs of corrosion, replace it.

I shared a picture of one of my packs that I completely discharged and disposed of because of physical damage from a crash. It’s tempting to keep such a pack and just watch it because the photo shows the balance is still perfect across the pack, but this pack isn’t safe. I can’t see what has happened internally that might suddenly cause it to destruct.

Yes, it hurts to toss out what appears to be a perfectly functioning pack, but safety is more important. Do not continue to use damaged packs.

Meters

With a wide selection of meters on the market, everyone flying electric-powered aircraft should have one of some sort. Most pilots can use a meter such as the Astro Flight Whattmeter—it’s reasonably priced and accurate.

Standard volt/amp meters are handy around the house for many reasons and can be used in our hobby too. Many are limited as to how many amps they can read and most limit themselves to 10. That’s not enough for most electric fliers. Shunts can be used to increase their flexibility, but most of us simply want to connect them and measure something.

These meters range from approximately $15 to $150. All work well for our purposes.

A couple of readers recently asked about using clamp meters. A clamp meter will work fine, but until recently, most were quite expensive. Fortunately, that’s no longer the case and clamp meters are a viable alternative.

You can search on Amazon or other retailers for “clamp meter” and find many choices. Be sure to look for one that will do DC current. My Sears Craftsman model costs approximately $70, but I found it on sale during Christmas for $39. Amazon has several clamp meters in the $30 range.

A clamp meter can be a handy device because you don’t need to unplug anything or find a place to hook it up in line with the circuit. Electric-power guru Keith Shaw has used one for years at fly-ins to check the current pulled by various airplanes when he is helping modelers.

Most of our setups have room to clamp the meter around one of the wires. Remember, if you’ve never used one before, you put the clamp around just one of the wires—not both!

They also can be used as regular meters with probes. Mine includes a temperature probe as well.

How Close Is Close Enough?

Whenever I reference a meter, I hear about the need for more accurate measurements. For an average modeler who isn’t an engineer developing equipment for NASA, any of the available meters are accurate enough. If you’re working in a laboratory, maybe not.

The accuracy is certainly close enough. There is a .02-amp difference in the readings. That could be attributed to losses between the first connection point and the second meter.

I recently heard from two readers who did some nice side-by-side tests of clamp meters that they bought on Amazon for $36 and an extremely accurate Fluke meter. They found that the meters were within a few hundredths of each other when measuring current. That’s more than close enough for our use. Don’t become wrapped up in worrying about thousandths of a volt or amp. We’re flying model airplanes, not space shuttles.

The Revolectrix Bump controller showed 2.19 amps, while the two meters read 2.19 and 2.17. That’s certainly accurate enough for our purposes.

Wrapping Up

We don’t need to be perfect, but we do need to know what our setups are doing. There is an abundance of gear out there to help us with that and not break the bank.

-Greg Gimlick
maelectrics@gimlick.com

Sources:

Amazon
www.amazon.com

Astro Flight, Inc.
(949) 855-9903
www.astroflight.com

Sears
www.sears.com

In the Air
Column
As seen in the April 2018 issue of Model Aviation.

AMA has partnered with AirMap, the world’s leading airspace management platform for unmanned aircraft, to integrate a situational awareness app for drone pilots.

AirMap for Drones is available through Google Play and the iOS App Store. AMA members can use the free app to find an AMA club flying field and to get real-time airspace information about their flights. This information includes determining if it’s a controlled airspace, if there is a Temporary Flight Restriction (TFR) in place, what air traffic is nearby, and updates on potential weather changes.

AMA members can also use the app to submit a digital notice if they are flying within 5 miles of an airport. Those with a Part 107 license can digitally request Low Altitude Authorization and Notification Capability (LAANC) authorization in US-controlled airspace at participating locations.

Dave Mathewson, AMA executive director, stated in a January 2018 press release, “AMA is excited about our new partnership with AirMap. The tools that AirMap provides will be a real asset in helping to educate our members about sUAS and help ensure that we continue to fly safely and responsibly.”

Pilots can make their own profiles, manage their aircraft, and view past flight plans with AirMap for Drones. You can learn more about the app at www.airmap.com/operators.

In the Air
As seen in the April 2018 issue of Model Aviation.

AMA Integrates App
AMA has partnered with AirMap, the world’s leading airspace management platform for unmanned aircraft, to integrate a situational awareness app for drone pilots.

AirMap for Drones is available through Google Play and the iOS App Store. AMA members can use the free app to find an AMA club flying field and to get real-time airspace information about their flights. This information includes determining if it’s a controlled airspace, if there is a Temporary Flight Restriction (TFR) in place, what air traffic is nearby, and updates on potential weather changes.

AMA members can also use the app to submit a digital notice if they are flying within 5 miles of an airport. Those with a Part 107 license can digitally request Low Altitude Authorization and Notification Capability (LAANC) authorization in US-controlled airspace at participating locations.

Dave Mathewson, AMA executive director, stated in a January 2018 press release, “AMA is excited about our new partnership with AirMap. The tools that AirMap provides will be a real asset in helping to educate our members about sUAS and help ensure that we continue to fly safely and responsibly.”

Pilots can make their own profiles, manage their aircraft, and view past flight plans with AirMap for Drones. You can learn more about the app at www.airmap.com/operators.

Written by Terry Dunn
A builder’s guide to common adhesives
How-to
As seen in the October 2013 issue of Model Aviation.

There’s a television commercial that reminds us to shop around for car insurance every six months, lest we miss out on a better deal. Maybe we should apply similar logic toward the glues we use. If you haven’t scanned your hobby shop’s glue shelf in a while, you may be unaware of some contemporary offerings.

As new materials have been ushered into the modeling realm, so have new adhesives. Likewise, new modelers are often unfamiliar with some of the classic hobby glues that have stuck around.

This article is not intended to be a comprehensive catalog of modeling glues, but is meant to serve as a broad overview of what’s available. This article also avoids the technical aspects of how and why glues work and behave the way they do. Chemistry never was my best subject, so I’ll stick to the basic properties and practical applications for each of the listed glues.

Polyurethane glues expand as they dry and fill gaps. This is useful when repairing damaged models.

In no particular order, the glues I’ve chosen to discuss are:

• Cyanoacrylate (CA): This is the most popular type of glue in all of modeling. I’m comfortable making that assumption. Thick, thin, foam-safe—at least one type can be found on nearly every modeler’s workbench.

Yet, CA is also one of the most hazardous glues on the list. Who among us has not glued his or her fingers together, ruined a pair of jeans, or cried from the fumes? Most of us are willing to accept and manage that risk for the reward of strong and immediate glue joints.

• Polyvinyl acetate (PVA): Most of us have been using (and perhaps eating) PVA glue since grammar school. Whether you call it Elmer’s Glue or white glue, you already know that it is ideal for attaching raw macaroni to construction paper. It is also useful for gluing balsa airframes together.

Yellow Carpenter’s Glue is also a PVA glue. It tends to be a tackier than white glue when wet, which is often useful.

• Canopy glue: Although canopy glue looks similar to common white glue, it performs differently. Canopy glue bonds well to nonporous materials and remains flexible when dry. These properties are what make canopy glue well suited for attaching plastic parts (such as a canopy) to the skin of a finished model.

• Goop: This household glue has a strong odor until it dries into a rubbery consistency. It sticks to nearly anything, but it will dissolve some foams (always test first). It works great on vibration-prone joints.

• Cellulose glue: Modelers have been using cellulose glues such as Ambroid for decades. It is still a favorite adhesive for weight-conscious and/or nostalgic builders. Cellulose glues can be thinned with acetone to the desired consistency and applied with a syringe for extra precision. When dried, the glue is lightweight and easily sands.

• Contact cement: There are many types of contact cement but they work in the same basic way. Glue is separately applied to each of the mating parts and allowed to dry, then the parts are combined for a quick bond. This is a popular adhesive for sheeting foam wings and building foamies.

• Epoxy: A longtime favorite for high-stress joints, two-part epoxy is hard to beat when strength is the main objective. It requires careful mixing to ensure proper curing and deliberate application to avoid excess weight.

Epoxy is available in versions with various working times (5-minute, 30-minute, 1-hour, etc.). There is an art to dispensing each part in equal amounts and also sizing the batch to have the right amount of epoxy for the job.

• Hot glue: Hot glue is applied using a gun-like, heated applicator. The low-temperature versions of hot glue can be applied directly to sheet foam without melting it. The quick drying (cooling) time of hot glue makes it ideal for assembly of flat foam models. Keep in mind that hot glue joints can get brittle in freezing weather.

Hot glue is handy for quickly assembling sheet-foam models. This fancy glue gun has a variety of applicator tips. Even inexpensive glue guns are effective.

• Polyurethane glue: This glue expands as it dries, making it ideal for repairing crashed models. Bond strength can be improved by poking holes in the mating surfaces. It can also be used for initial builds. Water (including humidity) is the catalyst that kicks off the curing process. Care must be taken to keep the bottle airtight between each use to prevent curing.

• Water-based polyurethane: This easily applied, brush-on liquid can be found in the household paint section at your local hardware store. It provides a lightweight method for adhering fiberglass cloth to balsa or foam models, although it does not provide the same degree of structural rigidity of an epoxy-based finish. It can also be used to laminate foam sheets together.

You may have a favorite glue or two that isn’t on this list. Be sure to share that secret adhesive with your flying buddies. More importantly, watch for new glues. It appears that there is always something new, and this week’s release might be what you’ve been looking for!

Learn more about building!

[Editor’s note: Because there are so many types and brands of adhesives, we don’t have the space to list websites for them all. A search of the Internet or a visit to your local hobby shop or home improvement store should provide any additional information you might need.]

—Terry Dunn
terrydunn74@gmail.com

New products that are Worth a Closer Look
Product review
As seen in the April 2018 issue of Model Aviation.

Although the Unicorn Edition motor from NewBeeDrone looks like a psychedelic callback to the land of the Care Bears, don’t be fooled. There’s a lot more power packed into this 6 x17 mm brushed motor than meets the eye.

Micro brushed quadcopters are as popular as ever, as are the upgrades hitting the market to increase punch, power, and performance. The Unicorn Edition motor fits right in with those enhancements, and even exceeds them in many ways. At 25,500 Kv, this 6 x17 mm motor set is one of the fastest ones on the market, and it’s a noticeable jump from the previous top-of-the-line motors from NewBeeDrone, the Gold Edition motors. For most situations, 40% to 50% throttle provided plenty of cruising speed while indoors, and running full throttle was like jumping to light speed!

There are some drawbacks to this kind of power. Flight time will suffer to some degree, although I found that if I wasn’t too hard on the throttle during a run, my times were consistent with slower motors. I averaged flights between 1.75 to 2.5 minutes on these motors. They can get very hot following a run, so take care in removing your battery, and be sure to occasionally give them time to rest.

One of the advantages to running a motor such as the Unicorn Edition set is the ability to take a micro quadcopter outdoors for some fresh air. With previous setups, outdoor flight was challenging, and not much fun except in the calmest of circumstances. Now, the ability to perform aerobatic maneuvers outside, even in light wind conditions, becomes more manageable. These motors provide more than enough power to pull out of dives, flip, and roll without fear of smacking into the ground, as has been the case with many previous setups.

Not all flight controllers are an optimal pairing for the Unicorn Edition motors. The motors’ high Kv rating can cause oscillating on some older Inductrix-style flight controllers; however, if you are using a Betaflight-based flight controller such as a BeeBrain v2 or BetaFPV F3 Evo, you’ll be sure to get the most out of these powerhouse motors.

The Unicorn Edition set of four motors retails for $19.99 and you can find out more about it at the NewBeeDrone website.

NewBeeDrone:
Website: www.NewBeeDrone.com
Email: info@newbeedrone.com

Written by Don Slusarczyk
Free Flight Indoor
Column
As seen in the July 2017 issue of Model Aviation.

I have flown with batches of 10/97 and 3/02 Tan II rubber for many years, and my reserves are running thin. I wanted to do some comparison tests between the old Tan II and the current batches of TSS to see how rubber has changed throughout the years.

Fred Pearce published two articles in the March and April 1979 issues of Model Aviation about his method of pull testing rubber. I have followed his method with one exception: I increased the 430 factor to 480 in his second equation, to adjust for the better quality of modern rubber.

Fred’s method was rather easy. A loop is made, stretched to a certain force, and held for five minutes. It is then stretched to a new force and the data recorded as it is relaxed. Fred’s testing device was rather large, so I decided to use shorter loops so I could test it in my model room.

Taking force and distance readings during a pull test.

For these tests, you will need a digital scale that will weigh up to 1 milligram. Knowing the exact weight of the rubber loop and knot is crucial for accurate results (see my past columns for scale suggestions). You will also need a pull scale to measure the force. I used the American Weigh AMW-SR-20 digital pull scale that reads up to .02 pounds. Next you will have to make a measuring board.

I printed some rulers I drew up in CAD with graduations every 1/10 inch and glued them to a 6-foot x 1-inch x 4-inch pine board. The peg to loop the rubber around is a piece of 1/8-inch brass tube with a bolt inside to attach it to the board. The last item you will need is a spring clamp to hold the scale in position during the testing.

Start by making up some motors to test. I set my rubber cutter to approximately .055 inch wide for all of the batches of rubber that I tested. Cut a 12-inch strip from one batch, weigh the strip, record the weight, then tie a knot in the loop using hemostats to clamp the rubber (commonly used in making F1D motors).

I found that three knots, each the opposite direction of each other, were needed for this kind of pull testing. The resulting loop should be 5.8 inch long. Now pull the loop to a specified force based on the following formula:

F1 (pounds) = 45 x weight in grams/initial loop length

The smooth tubing keeps the rubber from breaking during the test.

My 5.8-inch loop weighs .475 grams (minus .025 gram for the knot), so it has a rubber weight of .450 grams, which means the F1 force needed is 3.49 pounds. Now pull the rubber until 3.49 pounds is reached on the scale then hold it at that length for five minutes (using the spring clamp to hold the scale), and record the stretched length (L1).

After five minutes, relax the motor and let it rest for at least an hour to recover before performing the next test. You will see the loop is now longer than before.

This is the collected data for June 2016 TSS rubber. Remember that the first force value must be divided in half before adding to the rest of the force values.

The next step is to pull the rubber to a slightly higher force based on the data collected during the break-in stretch. This new force is based on this formula:

F2 (pounds) = 480 x weight in grams/L1

During the break-in process, the rubber was stretched to a length of 51.6 inches to achieve the 3.49 pounds, so using 51.6 as the L1 value in the formula, the F2 force is 4.19 pounds. Stretching to this final value puts a lot of stress on the rubber and knot, so I suggest that you pull slowly during the last 10% or so when you are getting close to the force value.

After you stretch to this force value, the data collecting begins. First, record the stretched length of the rubber at this force; the L2 length is used to calculate the rubber stretch ratio. Now move the rubber in 3 inches and measure and record the force at this new location. Move in another 3 inches and record the force, then another 3 inches and record, and so on until the motor is relaxed.

The data you have collected can then be used to calculate the stored energy of the rubber. The energy is calculated by first taking half of the F2 force and adding that to all of the other force values measured at the 3-inch intervals.

Total energy test results of various Tan II and TSS rubber batches, as tested by the author.

For my motor example, the force values were summed up to 16.295 pounds. Because I used 3-inch intervals, the energy formula can be simplified as follows:

Energy = 113.4 x summed forces (pounds)/weight in grams.

Using the sample motor, energy = 113.4 x 16.295/.45 = 4,106 feet-pounds/pound.

Stretch ratio = L2/initial loop length.

Using our data, that equates to 54.6 inches/5.8 inches = 9.41.

The stretch ratio can also be used to approximate how many turns the rubber loop will take.

Maximum turns: 4.7 x stretch ratio x loop length x square root of (loop length/rubber weight in grams).

Maximum turns = 4.7 x 9.41 x 5.8 x square root of (5.8/.45) = 921 turns.

A pull-test comparison of various common batches of Tan rubber.

I have included a graph showing various batches of Tan II compared with some of the latest TSS rubber. You can see some batches of older Tan II rubber had stretch ratios of more than 10 compared with TSS, which was slightly more than 9.

The June 2016 TSS rubber, however, has an energy total similar to some of the better Tan II batches. Because the total energy is similar, but the stretch ratio is 10% to 12% less, to get similar turns as Tan II, the TSS needs to be approximately 10% to 12% longer for loops of the same weight.

Until next time, keep the weights down and the times up!

-Don Slusarczyk
don@slusarczyk.com

Sources:

National Free Flight Society (NFFS)
www.freeflight.org

FAI Model Supply
(440) 930-2114
www.faimodelsupply.com

Model Aviation Digital Library
www.library.modelaviation.com

Written by Mark Fadely
Radio Control Helicopters
Column
As seen in the October 2011 issue of Model Aviation.

Hello all, and thanks for checking out this month’s RC helicopter column.

The outdoor flying season is nearing its end for much of the country, and smaller, indoor models will be logging most of the flight hours from now on. It is a good time to reflect on your successes and failures with helis during 2011. Did you accomplish what you had in mind for the year? Did you have a special goal that you attained, or are you happy just enjoying being involved in the hobby?

Pilots are continually learning new maneuvers while perfecting the ones they already know. For those who are curious about new tricks, here is a list and brief description of RC helicopter stunts that are slightly complex:

This is Blake McBrayer’s flybarless Gaui 255 model. Thecompany was one of the early developers of micro flybarless heads. This little heli flew over water and proved to be stable in all flight attitudes.

• Funnel—Sometimes called a pie dish, it is a circle flown sideways, either nose-up or nosedown. Getting the heli’s fuselage as vertical as possible makes this move difficult, but exciting.

• Death Spiral—At altitude, the heli is put on its side with the fuselage parallel to the ground. Then, collective pitch is zeroed and forward- or backward-elevator is held, causing the heli to fall on its side while flipping forward or back. Don’t forget the pull-out.

• Tic-Toc can be done with either aileron or elevator control. The helicopter cycles between a 10-o’clock and 2-o’clock fuselage position, with negative and positive collective pumps and cyclic control. Imagine a seesaw in a more vertical position.

• Pirouetting flip—The heli’s tail spins while it executes a flip. You must stir the cyclic stick to properly execute this maneuver.

• Chaos is a pirouetting flip that changes the nose orientation with each flip.

• Pirouetting globe—Consecutive loops while pirouetting and changing flight paths on each loop to simulate a globe.

• Tail slide—The helicopter is at a higher altitude when the nose is pulled up so the fuselage is perpendicular to the ground, and then the collective is neutralized. The heli falls with the tail pointed down. The helicopter can also be rolled during the slide.

• Snake—This is a series of left and right turns combined so the heli keeps moving in the same direction, while oscillating back and forth. There are many more moves than the ones listed. If one can do all of the tricks on this list, then he or she is in an elite group. Such maneuvers are what make 3-D flying so much fun. Pilot creativity is fueled by the helicopter’s expanded flight envelope and the extreme power-to-weight ratio of modern machines.

Blake shows off his charging box. He has six pro chargers that can charge 16 batteries at once. Some people might say that’s obsessive, but the author thinks it is fine!

There is no reason to quit practicing new moves as winter forces flying indoors. Some of today’s small models are 3-D capable— allowing small, indoor arenas to become aerobatic training grounds.

Another benefit is smaller models are less stable. The reduced stability requires pilots to be more proficient, which translates to more precision with larger models. Small helicopters require pilots to stay focused.

Learning new tricks with a heli can be frustrating because the pilot must relearn the move whenever orientation is changed. If a pilot is accustomed to doing Tic-Tocs with elevator control, then the same maneuver should be attempted using ailerons. The pilot should do the same with the helicopter facing the opposite direction. It’s difficult to master several orientations of the same maneuver.

My friend, Jason Russell, offered some advice on small, electric helis and what pilots should watch for:

“I see a lot of pilots jump ahead too quick in their flying. They see experts flying all the newest maneuvers and they want to do them also. This is dangerous because the heli might get into a position you are uncomfortable with and it could cause a crash.

Active in indoor events, Jason Russell is knowledgeable about micro and miniature helis and a proponent of flybarless helis.

“Pirouetting flips is one of the biggest, most attractive tricks that newer pilots want to try. It looks so easy when an expert is flying this complicated move. A lot of times, pilots will try to get through the maneuver with timing the controls. It is really difficult to do a pirouette using timing. It may work a few times, but then you are going to get caught in a position not knowing what to do and the heli is going to crash. More people need to take a slower, more logical progression to their flying.

“First of all, to do a pirouetting flip you must know how to do upright and inverted pirouettes while moving the heli around where you want it to go. This may sound a little simple, but try it. Most pilots have trouble just keeping the heli in one spot while pirouetting. So, it only makes common sense that if you can’t do that then you can’t begin to really learn a full-out pirouetting flip.”

Thanks, Jason.

The Rave 450 from Curtis Youngblood was converted to flybarless control.

This advice is common among expert pilots. It takes a disciplined pilot to learn all the fundamentals and basic flight orientations before moving forward.

To do the inverted and upright pirouettes, one needs to start with hovering with the nose pointed in each of the four directions. Move the nose 90° each time and hold the hover for at least 10 seconds at each spot.

If some pilots were asked to do both upright and inverted, many would struggle to control the heli. Sometimes people fly the same basic flight routine so many times that their flying looks excellent. But if you ask them to break it down and do simple orientations, they can’t do it.

This typically indicates that the pilot skipped a few important steps in his/her training, and then never went back and dealt with the orientation problems.

Skipping ahead or building on a weak foundation is not a good idea. RC helicopters are no different. Having a good grasp of the basics pays dividends.

Another up-and-coming genre for micro helis is Scale. This is Michael Lissing’s tiny military helicopter competing during the 2010 E-Fest Indoor Electric Festival.

Get out there and get some flying done. Do not let the cold, wet weather of fall and winter discourage flying. Get a good, small, fully aerobatic heli and fly it this winter. Next spring you will be a new pilot at your flying field! That is all for now.

-Mark Fadely

Sources:

International Radio Controlled Helicopter Association
www.ircha.org

Written by Allen Brickhaus
Learn more about the art of circle flying
How-to
As seen in the May 2014 issue of Model Aviation.

The Control Line modeling community has seen an influx of young novice pilots come into the hobby, plus older adults who have either returned to the circles from RC or jumped into the fray from their newly found interest in the event.

This article is focused on bringing readers information about how to enter CL in whatever event you would like to join. The Aerobatics or Stunt community is the largest CL community, but the classes of Carrier, Combat, Scale, Speed, and Racing are avenues in which you can further your skills.

Common CL flying is the use of a handle with a pair of metal stranded or solid wires connected to a simple bellcrank. The bellcrank is mounted in the body or on the wing and a set of pushrods goes to all of the control surfaces.

Allen Brickhaus displays his Bob Gialdini Rayette, which is available as a laser-cut kit by Eric Rule of RSM Distribution.

Power plants run the gamut of ignition engines with either glow or gas for fuel, plus glow fuel in either a two-stroke or a four-stroke configuration. Electric motors have become an important aspect in CL. There are plenty of experienced modelers who can help you set up and run glow, ignition, or electric power plants.

The Stuka Stunt forums and Stunt Hangar are two Internet sources that can provide knowledge of a variety of venues, classes, and information about many forms of CL modeling. They can introduce you to many professional and home-based supply sources.

Magazines and periodicals to read include Model Aviation, the Precision Aerobatics Model Pilots Association (PAMPA) Stunt News, and Control Line World. These magazines will provide a vast amount of information and guidance and can lead to other connections and advertisers.

For those who use internal-combustion power plants, there are a variety of engine tuners, which will help make your engine run smoothly and reliably. Three-wire lines and electronic controls will also assist those who want to go into Scale and Carrier. The ability to control the engine’s speed and thrust is imperative in those venues.

The ARF and kit versions of the Flite Streak are sold by Brodak Manufacturing. This model’s electronics are explained in the article. Joe Daly and Kevin DeMauro hold a Flite Streak trainer.

Listen to experts concerning which fuels to use. The type of engine you use dictates which fuel to use.

All AMA CL events must use a handle thong attached to the pilot’s handle and the model and the thong will be “pulled” to ensure that the lines and the model are safe to fly. Most models are weighed and then a “pull” number is given to the pull tester. Different events have different pull-weight requirements.

Aerobatics

Aerobatics is a set of maneuvers that is worldwide in nature and use. What you would practice in the US would be a viable “pattern” anywhere else in the world.

The FAI and AMA patterns are nearly the same. The number of laps before the Overhead Eight, the time limits, and how the landing is judged are the main differences. Local aerobatic pilots will be glad to help you interpret the set of maneuvers and guide you through the flight.

Old-Time Stunt and the Beginner Pattern are different and you should utilize the help of pilots who are more experienced in those fields.

Navy Carrier

Carrier is an event set up to emulate a carrier flight, complete with a semicircular wooden or concrete carrier deck. The models are encouraged to be similar in looks to the original aircraft the pilot has decided to copy.

The models are flown off the fore end of the carrier deck at full throttle and timed for seven laps. Then the pilot will slow the model, drop its landing gear hook, extend ailerons and flaps, and use the elevator offset to keep the model out on the end of the lines while being timed for seven slow laps.

After those two opposite speed sections are timed, the pilot must land the model on the deck on the first designated pass over the wires set up to catch the model. The sooner the pilot puts the model safely down, the higher the landing score.

The model should land with the engine still running. All of the landing gear should be setting on the deck and the aircraft’s attitude should resemble a full-scale landing to gain the most landing points.

Combat

Combat is an event that has been classified as more exciting than an armpit full of fleas. Two pilots attach crepe paper streamers to the end of his or her model and they simultaneously launch. Different classes have slightly different rules, but the idea is to cut the opponent’s streamer for points.

Unless you are flying in a Profile World War I or II Combat event, the models are normally nondescript wings with an engine pod and whatever tail feathers he or she needs to maneuver the model into position to cut the other airplane’s streamers.

Taking or cutting your opponent’s streamer, while retaining your own, is one goal of CL Combat. Not tangling your lines while flying Combat is a challenge.

Combat classes are designated by engine size and types of models allowed. Join the audience at the Combat circle for an exciting time.

Racing

CL Racing entails a variety of classes, depending upon engines, models, and local rules. FAI Team Race is the epitome of professional racing, with as many as three pilots flying slick-looking, diesel-powered models. Similar, lower-budget racing events include Clown Race, Foxberg Race, and a variety of others.

Races are not always won with the fastest airplane. Pit stops are required and the pilot/pitman team must execute their stops to refill the fuel tank and get the model back in the air in a minimal amount of time.

A CL Formula 40 racer is ready for its next flight.

If you enjoy Formula 1 or NASCAR racing, this similar type of activity might interest you. A model airplane costs less than an expensive race vehicle. I spent some time drag racing with my ’55 Chevy and do see the difference in overall cost!

Speed

Speed models are designed to do nothing but go fast. Most speed models begin as a magnesium-molded pan and the upper structure is generally finely finished, polished wood. Models are classified by engine size and include a jet category.

Speed models are set in a bent-wire frame with wheels called a dolly. The model is released by a pitman and the airplane accelerates. The pilot must put his handle in a U-shaped cradle at the center of the circle. This allows exact timing and keeps the pilot from illegally “whipping” his airplane to higher speeds.

This CL Speed model uses a bent-wire frame with wheels called a dolly to launch the aircraft.

The goal is to achieve the best speed with the same length of lines. Three sites—California, Buder Park in St. Louis, and the AMA site in Muncie, Indiana—have speed cages in which to safely fly these models.

Scale

Scale modeling is self explanatory, but classes are separated by skill levels. The models must represent a full-scale airplane that actually flew. Documentation is needed to achieve the best static scores in the initial scoring. The pilot must give the Static judges drawings, color pictures, color artwork, and single-view up to five-view drawings of the model he or she will fly in the event.

Documentation experts suggest that you should present whatever evidence you have for the model, but not to present documentation of features that are not on the model so it is as close to scale as possible. Static scores are typically not posted until the pilot has completed at least one flight.

Flight scores are achieved by setting up a series of maneuvers, dropping bombs, lowering and raising the landing gear, pulling streamers in the air, or other scalelike details in the flight pattern. How well the pilot performs his or her designated flight pattern determines the flight score.

The static and flight score are combined to determine the winners.

Finding a Club

I suggest using the model club locator on the AMA website and searching for a CL club near you. I encourage you to visit a club, watch the club members, decide what type of flying you might enjoy, and ask advice to improve your knowledge and gain guidance in your choice of CL flying.

Find a working combination of model, engine or motor, fuel tank, and choice of fuel and controls, as well as building and finishing skills that impress you, and copy the example you like to the best of your ability. Taking advice from different people is wonderful, but you must be careful to not gather “this” from one person, “that” from a second modeler, and “the other” from a third. Different perspectives may not work in conjunction with other ideas.

Jeff Witt’s beautiful JNA-D2 Jenny competed in CL Scale at the 2011 Nats. Ted Kraver photo.

Until you gain more experience, try to copy a successful process. After you have accomplished this goal, branch out. Be careful to not experiment too much and waste time going down a dead-end avenue.

Electric Power

William DeMauro has shared his insight for those interested in using electric power to re-enter CL. He and other CL fliers in the New York City area have been using a profile electric ARF Flite Streak to teach interested young pilots how to fly and to reintroduce older pilots who have been away from CL for a number of years.

The Flite Streak makes a good training airplane for a number of reasons. It is easily obtained from Tower Hobbies for $80, or even less if you have a coupon or catch it on sale. Flite Streaks are well built and assembly only takes an hour or two. The controls can easily be detuned to make the airplane less sensitive for a beginner or a person with slower reflexes.

The model’s only fault is that some seem to come with no outboard tip weight in them. It is easy to slice the MonoKote at the tip and check to see if it is there. If not, add roughly 3/4 to 1 ounce of weight to the outboard tip.

The Flite Streak is an easy airplane to convert to electric power using inexpensive LiPo batteries and outrunner motors. The conversion process has been thoroughly discussed on Internet forums such as Stunt Hangar.

Will’s son, Kevin, used an electric-powered Flite Streak for nearly three years while learning the Stunt pattern. He would set the timer for a 1-minute flight to get accustomed to flying. His enthusiasm grew and by the end of the first year he was making 5-minute flights and doing loops.

Perfect motor runs made it easy for him to concentrate on his flying and by the end of the second year with that airplane, he was flying inverted and doing outside loops. In his third year, 2011, he placed second in the Nats with the model. Kevin wanted a bigger, more-advanced airplane and moved on to a Banshee. His Flite Streak was set aside for training purposes.

During 2012, the Flite Streak was used to teach Will’s nephews and a few other children the basics of CL flight. Will’s father, Harry DeMauro, decided that he wanted to try it and flew for the first time in roughly 15 years!

“He really enjoyed it and ended up flying about 15 flights in 2012,” said Will. “He has some problems with dizziness and with the E-power, but I was able to slow the airplane down to a speed he could handle. He has already been out flying a few times with us, and he has really enjoyed the plane.”

In 2013, Will met Joe Daly who had flown CL from the 1970s until approximately 1991. Will saw Joe’s posts on the Stunt Hangar forums and realized that he lived less than 10 miles away. “I reached out to him and invited him to Flushing Meadows Park [FMP] to fly with us,” said Will. “He came out with a gas-powered Mustang Stunter that was built 25 years ago. It had a motor that simply would not run properly. When he saw that most of us were flying electric-powered airplanes, he started asking tons of questions and reading everything he could on electric-powered CL planes.”

Joe had a Forerunner that he wanted to convert to electric power. Will told him to get in touch with Ron Heckler and to copy his system exactly and showed him the mounting system used on the Flite Streak. “I told him to copy it to his profile model,” stated Will.

“Joe is having lots of success with his electric Control Line airplane. He is now flying regularly with us at FMP. Joe’s son, also named Joe, got reintroduced to Control Line flying when he flew his dad’s electric Forerunner. Before that he hadn’t flown a model in 25 years.”

As a result of that experience, Joe bought an ARF Flite Streak and electric power setup. He will fly that and teach his 10-year-old son, Joe, to fly with it.
“If it weren’t for these power systems, it is likely that Joe would have become frustrated and given up CL flying again,” said Will. “Thanks to these power systems, we now have been able to add a person to our regular flying sessions in the New York City area.”

—Allen Brickhaus

Sources:

Stuka Stunt forums
www.clstunt.com

Stunt Hangar
www.stunthanger.com

PAMPA
www.pampacl.org

Control Line World
www.brodak.com/control-line-world

Flite Streak
www.towerhobbies.com

Written by Troy Hamm
This military trainer makes a great sport model.
Product Review
As seen in the June 2018 issue of Model Aviation.

Specifications

Model type: Semiscale ARF
Wingspan: 56.5 inches
Wing area: 536.7 square inches
Length: 46.2 inches
Weight: 80 to 88 ounces
Power system: .46 to .55 two-stroke; .70 four-stroke; or 925-watt electric
Radio: Four-plus-channel radio; four or five servos
Price: $159.99

Pluses

• Preinstalled control surfaces.
• Fast assembly.
• Good instructions.
• Decal set included.
• Pilot figure included.
• Well built.
• Flies great.

Minuses

• The instrument panel decal wouldn’t adhere to the painted wood panel.

Bonus Video

Product Review

The Fairchild PT-19 is a low-wing, open cockpit, two-passenger, conventional-geared aircraft that was designed to be a primary trainer. Fairchild received its first order for the PT-19 from the U.S. Army Air Corps in 1939. The PT-19 was also used by the Royal Air Force and the Royal Canadian Air Force.

Several versions of the PT-19 were built with a variety of inline engines. The PT-19 airframe was later adapted to use a Continental radial engine and designated the PT-23. More than 7,000 PT-19s were built in all.

The Great Planes PT-19 was shipped in one medium-size box. All of the components were sealed in heavy plastic and I found no damage. The PT-19’s construction is balsa and light plywood with Top Flite MonoKote covering. The cowling is constructed of high-quality fiberglass and the quality of the paint work is exceptional. One nice feature is the factory-installed control surfaces; they are prehinged and already glued in place.

The Great Planes PT-19 Sport Scale .46/EP ARF is a versatile airframe that can be powered by glow or electric. I chose an O.S. Max .46 AX II two-stroke engine with a Bisson Pitts muffler to power my PT-19.

For the radio equipment, I used a Futaba T14SG transmitter, Futaba R2006GS receiver, and five Tactic TS X25 mini digital servos. A Tactic switch harness, four Tactic 12-inch servo extensions, and a LiFe Source 1,300 mAh receiver battery completed the list of electronic equipment used.

The Great Planes PT-19 is ready for assembly.

Assembly

Included with the PT-19 is a 23-page instruction manual with black and white pictures. The first section in the manual is called “Preparation.” This section instructs a builder on how to use a covering iron to reshrink any loose covering on the airframe.

It only took 10 minutes to get the wrinkles out of the covering. If the airplane will be powered by a glow engine, the manual recommends sealing the firewall and motor box with either epoxy or CA adhesive. I thinned 30-minute epoxy with a few drops of rubbing alcohol and used a brush to apply it to the firewall and motor box.

The next section covers the wing assembly. Included with the kit is a section of 1/2-inch heat-shrink tubing, which is used to secure a servo extension to the aileron servos. When the servo is secured in place in the wing, the control horn and servo linkage were installed.

I used 30-minute epoxy to secure the two wing halves together. After the epoxy on the wings has fully cured, the main landing gear is installed in the wing. One nice feature of the kit is the landing gear wires come with preground flat spots for the wheel collars to attach to. This completes the wing construction.

The landing gear and landing gear strut covers fit well and look great.

Fitting the wing to the fuselage is the next step in the assembly process. An addendum is included with the manual that explains the test-fitting process. If the wing tab doesn’t fit in the slot in the fuselage former, a simple adjustment will provide a good wing-to-fuselage fit. My wing fit perfectly and did not require any adjustments.

I used 30-minute epoxy to secure the vertical and horizontal stabilizers in place. The epoxy provides a strong bond and allows plenty of time to ensure that the stabilizers are perfectly aligned with the fuselage and the wing. After the epoxy has dried on the stabilizers, the tail wheel assembly is installed in place with three screws.

The manual has a separate section for mounting either an electric or glow powerplant. The glow engine installation section details everything needed to install an O.S. Max .46 AX II with either a standard or a Bisson Custom Mufflers Pitts muffler. Installing the motor mount on the firewall requires drilling four 5/32-inch holes. The mount is then bolted in place with the included hardware.

The builder will need a #36 drill bit and a 6-32 tap to mount the engine on the motor mount. All of the components needed to install the throttle servo are included in the kit, as well as a glow fuel tank and glow fuel line. The instructions are very thorough and it takes less than a half hour to install both.

Installing the cowling is the next step in the Great Planes PT-19 build. The key to getting a nice-fitting and nice-looking cowling is to take your time and go slowly. Cutting the cowl is always one of the last steps in completing an airplane, and many modelers are so anxious to finish their airplane and get it flying that they rush through this part of the assembly.

The instruction manual does a great job of explaining how to cut the relief holes for the cylinder head, carburetor, and muffler exit. I used a rotary tool and sanding drum to make the cutouts in my cowling. The manual recommends wearing eye and breathing protection when cutting fiberglass, which is good advice.

The O.S. Max .46 AX and Bisson muffler work well on the PT-19.

If the PT-19 is built as an electric-powered aircraft, no cutting on the cowling is required. Great Planes provides two cowl attachment options. A cowl ring is included for flush mounting the cowl, or the cowl can be secured with two screws on each side. A Great Planes aluminum spinner nut was used to secure the APC 11 x 6 propeller in place.

The rudder and elevator servos were installed in the fuselage using the mounting hardware that was included with the servos. After the rudder and elevator control horns were screwed in place on the control surfaces, the pushrods were attached to the servos.

The six-channel Futaba R2006GS S-FHSS receiver and LiFe Source 1,300 mAh battery pack were secured in the fuselage with the included hook-and-loop material. Installing the receiver switch in the side of the fuselage completed the radio installation.

The last assembly step is installing the instrument panel decals, pilot figure, crash protector, and the two windscreens on the hatch assembly. Two instrument panel decals are included with the kit. The larger decal is installed on the rear front cockpit panel. The decals did not adhere well to the painted cockpit panel, so I applied Pacer Formula 560 Canopy Glue to the back of each instrument panel decal before installing it.

The instrument panel and pilot figure add a nice scalelike touch to the PT-19.

Pacer Formula 560 Canopy Glue was also used to secure the crash protector and the windscreens. The canopy hatch assembly is held in place with a single spring-loaded canopy latch. This allows quick hatch removal with no tools necessary. The remaining decals were installed in the locations pictured on the PT-19’s box. They give the airplane a nice look.

Great Planes even included a decal for the owner’s name, address, AMA number, and FAA registration number. I placed it on the underside of the wing near the wingtip.

I programmed my Futaba T14SG transmitter with the control surface deflections that were suggested in the manual. The manual did not recommend exponential settings. I programmed my transmitter with a negative 30% on low rate and a negative 40% on high rate for the elevator, rudder, and ailerons. Negative exponential is used for Futaba radios; some other brands use positive exponential.

The last step in programming the transmitter was setting the failsafe and the throttle cut. The manual recommends a center of gravity (CG) of between 23/4 and 33/4 inches back from the wing’s leading edge when measured at the fuselage. With the radio equipment installed as pictured in the instruction manual, my model’s CG fell in the middle of that measurement.

The Great Planes PT-19 was ready for its first trip to the flying field.

Flight Report

At the flying field, the PT-19 was given a range check and a thorough preflight inspection. The O.S. Max .46 AX II engine started easily and had a great throttle transition with the factory needle-valve settings. The Bisson Pitts muffler did a good job of quieting the engine noise.

There is plenty of room in the fuselage for the electronic equipment and fuel tank.

The Great Planes PT-19 tracked straight on takeoff and was airborne in less than 100 feet. For straight-and-level flight, the PT-19 required two clicks of right rudder trim and only one click of up-elevator trim. The O.S. Max .46 AX II provided more than ample power for the PT-19. The climbout and vertical performance are impressive.

Although the test flights were flown on a windy Kansas day, the PT-19 was stable and handled the conditions without difficulty. I found that the roll rate was slightly slow while on low rate settings, but with the high rate setting selected, the PT-19 easily performed basic aerobatic maneuvers, including rolls, loops, and spins.

I found that the PT-19 was stable while flying inverted. Roughly a third forward stick (on high-rate elevator setting) was required to maintain straight-and-level inverted flight. I did not experience any bad flying characteristics with the PT-19—no tendencies to tip stall or snap roll when the airspeed is slowed down for landing.

The Great Planes PT-19 easily completes takeoffs and landings.

Overall, the PT-19 is a relaxing airplane to fly. Takeoffs are easy and it lands at approximately the same speed as most trainers. This was my first experience using Tactic TSX-25 Mini Digital servos. I am impressed at how well they center and provide a locked in feel with the aircraft.

Conclusion

Assembling the Great Planes PT-19 is straightforward, and the instruction manual explains each step well. The quality of the included hardware is good, and the fit and finish of the airframe are excellent.

Pilots of nearly every skill level will find themselves at home flying this model. The Great Planes PT-19, combined with the trouble-free operation of the O.S. Max .46 AX II, makes for a great-looking and great-flying airplane.

—Troy Hamm
funflyr@juno.com

MANUFACTURER/DISTRIBUTOR:

Great Planes
www.greatplanes.com

SOURCES:

Futaba
www.futabarc.com

O.S. Engine
www.osengines.com

LiFe Source
https://lifesourcebatteries.hobbico.com

Bisson Custom Mufflers
(705) 389-1156
www.bissonmufflers.com

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

Pacer Formula 560
www.zapglue.com

Written by Dan Gaston
An enjoyable homebuilt aircraft
Product Review
As seen in the June 2018 issue of Model Aviation.

Specifications

Model type: Semiscale ARF
Skill level: Intermediate
Wingspan: 85 inches
Wing area: 1,551 square inches
Length: 73 inches
Weight: 17 to 19 pounds
Wing loading: 25.3 ounces per square foot
Power system: 30cc gas or electric equivalent
Radio: Spektrum DX18 transmitter; Spektrum AR9020 receiver; eight Spektrum A6180 digital metal gear servos
Construction: Balsa and plywood
Needed to complete: Power system; radio gear; fuel or batteries
Flight duration: 10 to 12 minutes
Price: $449.99

Pluses

• Covered in UltraCote, which means any repairs will match precisely.
• Beautiful fiberglass cowling, wheel pants, spats, and cuffs.
• Scale hinging and no exposed servos.
• Included cockpit details and painted pilot bust.
• Rock-solid flight capabilities.
• True-running and heavy-duty 4-inch spinner included.
• Included decal sheets for four schemes.

Minuses

• A couple of mistakes in the assembly manual.
• Accessibility of ignition and radio batteries.

The Hangar 9 RV-4 on a low, fast flyby. This view shows how clean the design is. The model flies well and had no problems operating from a grass runway.

Bonus Video

Product Review

The Van’s Aircraft line of homebuilt, full-scale airplane designs is an extensive one with a long list of satisfied customers. With proven designs that cover a range of private pilots’ needs and desires, it’s no wonder they are so popular.

In that extensive line is one design that, in my opinion, is the aviation world’s version of a hot rod. Luckily for us, Hangar 9 has chosen to bring to the market an ARF version of that little hot rod—the Van’s RV-4.

Featuring an 85-inch wingspan and designed for 30cc gas engines (or equivalent electric motors), this is a big model, but not so large that it requires a van or trailer for transport. Although aerobatic, it won’t give a true 3D model a run for its money. But as a sport airplane, it’s got the additional appeal of being scalelike in appearance.

With an airplane this pretty, any RC pilot should be content to rip around a local airfield for years to come, but might I suggest something more? The Hangar 9 RV-4 is an ideal airplane with which to enter your first RC Scale contest.

For starters, it has the size and weight to relegate all but the worst wind to “no factor” status. Because it’s aerobatic, you won’t have to fly a boring routine of traffic-pattern maneuvers. If your excuse for not competing in RC Scale has been, “All I have is an ARF,” that is no longer a legitimate excuse.

The 2017 AMA RC Scale Nats was filled with ARFs—heck, they even allow them at Top Gun now. Don’t let RC Scale competition be one of those things that you could have or should have done. Go to the website of the National Association of Scale Aeromodelers (NASA; the AMA Scale Special Interest Group) to find out more.

After removing all of the contents from the apartment-size box, I was immediately impressed by the completed scalelike hinging on all of the control surfaces! The list of niceties goes on—not the least of which is a beautiful fiberglass cowling with paint that perfectly matches the fuselage covering. Well done, Hangar 9!

This photo emphasizes how well the many painted fiberglass parts match the covering on the RV-4.

Next, I set about inventorying everything to see what additional items I needed to purchase from my local hobby shop. When that list was complete, I sat down and thoroughly read through the instruction manual. The manual for the RV-4 is done in the usual Hangar 9 fashion, which means it’s a nice booklet loaded with pictures and written instructions.

The manual begins with outfitting the wing halves, which is nothing more than installing two servos and their associated linkage in each half and epoxying the aileron horns in place. Before you mix the epoxy to install the aileron horns, gather the elevators, rudder, and their associated horns and glue all of them at the same time. That way, everything is ready to go when you get to that step.

The well-illustrated manual contains no fewer than 30 photos to guide the owner through the process of wing preparation. A small, but significant, mistake was found in the manual where it states to drill out the flap control horn with a 3/32 drill bit. The proper bit size is 1/16 for a slop-free linkage setup. On the subject of the flaps, the concealed linkage and servo setup procedure outlined in the manual might seem unorthodox, but follow it and you will see that it works well.

The final wing assembly steps are the addition of the flap linkage shroud and wingtip light lens. For this I used ZAP Formula 560 glue, which I also later used to secure the canopy to the cockpit. The wingtip lights are fully functional. Because of time constraints, I was unable to utilize them for this review, but they will be hooked up in the future.

Moving onto the fuselage, I began the radio installation by varying from the manual when it came to servo layout. The manual shows the rudder servo flanked by the two elevator servos, with all three output shafts toward the front. With a 3-inch tiller bar for the pull-pull setup on the rudder servo, I was concerned about how well this would work. I installed the rudder servo with its output shaft to the rear, removed all but the necessary elevator servo output arms, and ended up with a roughly 1/16-inch clearance, no matter the control inputs.

Next was the installation of the vertical stabilizer, which is simply epoxied to the fuselage. The manual suggests that you mix 3/4 ounce of 30-minute epoxy for this procedure. I assure you that it can be secured with far less.

The horizontal stabilizers slide over a carbon-fiber spar tube and are secured to the fuselage with 8-32 button-head machine screws.

I found another mistake in the manual for the tail wheel installation. If a hole is drilled in the bottom of the rudder at the suggested 45/8 inches aft of the hinge line, this hole will be merely decorative. I installed the tail wheel assembly and used the tiller arm to locate the holes for its mounting.

The main gear installation—with all of the swoopy streamlining fiberglass bits—is actually straightforward. I first coated the bare plywood beneath the landing gear legs with 30-minute epoxy, knowing that exhaust has a way of seeping into this area and softening the wood. To secure the landing gear fairing to the cuffs, which are, in turn, secured to the fuselage at one end and the wheel pant at the other, I used a great product called Foam-Tac adhesive. Foam-Tac is a thick, clear glue that fills gaps well and remains flexible. I get mine through West Michigan Park Flyers. The difference that these wheel pants and fairings make in the model’s appearance is stunning.

At this point, I slipped the cowling on to get a peek at the completed look. I was not disappointed.

I gathered all of the necessary items and set about mounting the engine, which normally is a rather involved process. From placing the included (and much appreciated) drilling template against the firewall, to tightening the final engine-mounting bolt on the Evolution 33cc engine, total elapsed time was approximately 20 minutes. What’s more, the throttle linkage was even simpler.

Evolution gas engines are built on traditional model engine architecture, providing a level of familiarity for someone accustomed to a glow engine.

The muffler installation, however, was quite another story. No problems were encountered with the model or any of the equipment—it’s simply an involved process to fit a cowling over an installed muffler.

I was provided an Evolution Pitts-style muffler for this review. All that’s required to mount it to the engine is two bolts. That’s the easy part. It’s nothing out of the ordinary—just the many measurements, rechecking those measurements, placing and removing the cowl, and eventually attacking that gorgeous cowl with a Dremel tool to make clearance cutouts. Of course, all of this is unnecessary if you’re going the electric route.

An optional Pitts-style muffler, LiFe batteries, aluminum servo arms, servo extensions, switches, a fuel filler, and Spektrum metal gear servos round out the equipment used in this review.

To obtain the balance point of 61/16 inches behind the leading edge, it was necessary to place the two 3,000 mAh 2S LiFe batteries against the rear of the bulkhead to which the engine mount box is mounted. I also had to secure 9.5 ounces of weight to the engine stand-offs. If I mounted the batteries at the forward edge of the engine box as shown in the manual, the required dead weight would have been less. To access the batteries for charging would require removing the spinner, propeller, and cowling.

There is a hatch on the bottom of the fuselage just aft of the landing gear through which I can access the batteries. To make it possible to leave the batteries secured in the fuselage, I’m utilizing a balance lead extension in addition to a long charge lead.

At this point, after only a few evenings of simple assembly, everything is ready for the maiden flight other than the initial break-in runs of the Evolution 33cc engine. This break-in was carried out by following the instruction manual to the letter.

Flying

Much trepidation goes along with a first flight and this was no exception. I soon discovered that whatever amount of time I spent fretting about the maiden flight was wasted. This airplane proved itself stable and true from the moment the takeoff roll began. After the usual minor trim adjustments, the Hangar 9 RV-4 felt as comfortable as something I’d been flying for a while.

After the obligatory photo passes were completed, it was time to open up the tap a bit and see what the RV-4 was capable of. Even with the Evolution 33 running somewhat rich as it continued its break-in, large loops, Immelmann turns, and hammerheads were all possible. When broken in and tuned accordingly, this engine should prove to be more than enough for the 17-pound airplane.

Rolls, both axial and opened up into a barrel style, are easily accomplished and made me look far better than my skills dictate. Inverted flight is another easily accomplished feat for this airplane. I can sum up the entire flight envelope of the Hangar 9 RV-4 in just one word: solid. It feels like a near-perfect blend of size, weight, power, and agility.

As pleasurable as any first flight might be, the airplane must still be brought back down for its first landing. It’s as simple as lining it up with the runway, bringing the throttle down after clearing the threshold, then giving it the slightest bit of elevator for a perfect flare.

The flaps were used on subsequent flights, and they were indeed effective with little pitch change. The flaps add a new, fun dimension to your flying, but if you decide to take the plunge into Scale competition, they also represent 10 free mechanical option points.

Conclusion

The Horizon Hobby Hangar 9 Van’s RV-4 proved to be an enjoyable model to fly and a perfect option for anyone interested in getting started in RC Scale competition.

The author chose the simplest of the available decal schemes to allow the airplane’s lines to speak for themselves.

—Dan Gaston
dagaston1431@gmail.com

Manufacturer/Distributor:

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

Sources:

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

Foam-Tac
(914) 699-3400
www.beaconadhesives.com

West Michigan Park Flyers
(616) 667-1809
www.wmparkflyers.com

NASA
www.nasascale.org

Written by George Kaplan
Warbird Excitement comes in a convenient size
Product Review
As seen in the June 2018 issue of Model Aviation.

Specifications

Model type: Semiscale ARF
Skill level: Intermediate to advanced
Wingspan: 67 inches
Wing area: 825 square inches
Airfoil: Symmetrical
Length: 58 inches
Weight: 11 to 13 pounds
Power system: 20cc gas engine or equivalent electric motor system
Radio: Five-channel minimum, six-channel for retracts; six standard servos or seven if gas powered
Price: $399.99

Test-Model Details

Engine used: Evolution 20cc gas
Propeller: APC 15 x 8
Radio system: Spektrum DX18 transmitter; Spektrum AR9350 receiver; seven Spektrum A6110 servos
Ready-to-fly weight: 12 pounds
Flight duration: 15 minutes

Pluses

• All laser-cut wood construction.
• Huge battery, radio, and tank hatch with a quick-release latch.
• Two-piece, plug-in wing with aluminum tube.
• Many scale extras included (dummy radial engine, an antenna, guns, bombs, etc.) that can be added to suit your taste.
• Three scale sticker sets included.
• Designed for included fixed gear or optional electric retracts.
• Cowl is attached with hidden bolts for a cleaner, scalelike look.
• Functional flaps work well and aid in slowing the aircraft for landings.

Minuses

• The included drill template to mount the Evolution 20cc engine was not correct, leaving holes that were spaced 0.5 inch too wide.
• Wing bolt holes in the fuselage did not align properly and required work to elongate.

The author found the Hangar 9 P-47 Thunderbolt 20cc to be an absolute joy to fly. From the maiden flight through dozens of sorties, its wide flight envelope gives it the ability to do everything a warbird should do and more.

Bonus Video

Product Review

I know what you’re likely thinking: Oh, boy, another P-47 ARF. There are probably more P-47 models on the market right now than at any other time, so what makes this one worth looking at?

If you want to add an average-size warbird to your fleet, this Hangar 9 20cc P-47 is a great-flying model, and the Evolution 20cc engine is a perfect match for the airframe.

Now that I’ve shown all of my cards, stick with me and let me explain to you what Horizon Hobby has come up with. It’s not without a couple of problems, but I’ll tell you how to get around them.

Although the P-47 was never one of my favorites, I’ll show you why this Republic Razorback now is.

The kit comes in a large box and everything is held in place with miles of clear shipping tape. All of that tape did its job because the parts made it from the factory to my shop with no damage, dents, or even scuffs from parts rubbing together.

After taking the time to unpack and inspect everything, I was pleasantly surprised to find that the entire airframe is constructed from balsa and plywood—no foam here. Everything was nicely rigid and robust.

A lot of care and planning look to have gone into the design and there are many laser-cut, interlocking pieces that make up the structure of the fuselage and both wing halves. Yes, there are quite a few vacuum-formed plastic bits, but these are mostly smaller to add scalelike details here and there.

The airframe is covered with a pressure-sensitive “stick-on” type of covering with a satin aluminum finish. Printed on this covering are all of the panel lines, hatches, the stars and bars, and invasion stripes.

A solid grouping of hardware is included. Whether it’s the larger things such as the fixed shock-absorbing main gear, the foam tires, and the tank, all the way down to the hinges, motor mounts, clevises, and control horns, all of the hardware is included, and it is all of good quality.

Fixed main gear is supplied in the kit, but Horizon Hobby sent along these optional electric retracts for the review model. They feature an oleo strut for shock absorption and have been rock-solid from the get-go.

I mentioned some scale detail pieces earlier. It’s worth adding that among these parts is a pilot figure, several vent/exhaust ports, and a dummy radial engine. Surprisingly, two completed bombs and two wing pylons are also included.

If you were to try to add these to any warbird, it would take a while to design your own or adapt what might be available on the market. With Horizon Hobby including these in the kit, it not only saves you time, but you get more value for your money and have great-looking, removable hardware that matches the scale of the P-47.

One final part to highlight is the well-made fiberglass cowl. It’s prepainted and matches the color and detail of the fuselage well. The P-47 is precovered in a nondescript, brushed-aluminum color scheme with D-Day invasion stripes. You can choose to leave it like this or utilize one of the included sticker sets to add the markings and nomenclature of three well-known full-scale Thunderbolts (Pengie II, Silver Lady, or Burma Yank).

The P-47 comes precovered in this attractive aluminum scheme with D-Day invasion stripes. It also includes a wealth of scalelike details such as a dummy motor, ordnance pylons, dummy bombs, exhaust ports, and an antenna.

Assembly

Now that you have an idea of the individual parts of this P-47, let’s dive into the manual and see how all of these pieces fit together. A copy of this manual is available on the Horizon Hobby website and the link can be found in the “Sources” section.

Assembly starts with installing the flaps. Using the included horns and hinges, they are fitted into the precut holes and slots and held in place with epoxy. Ailerons are attached next and utilize CA-type hinges. The aileron control horns are epoxied in position and the aileron servos are mounted inside of the wing on removable hatches.

After hooking up the pushrods and clevises, the flap servos are installed. It’s worth noting that the flap servo compartment is larger and there’s room for two servos in each bay. It is the first time I’ve seen this, and it makes sense because you can properly mount a wide range of servo brands, allowing both servos to operate as needed without reversing a Y harness.

On each wingtip, there’s a two-piece vacuum-formed navigation light that needs be attached. Each piece must be cut out and trimmed then canopy glue is used to hold it in place.

While the navigation lights are setting up, the main gear can be attached. As noted earlier, the kit comes with fixed gear, but this review model came with optional electric retracts.

Instructions to cover either mounting option are included and I found that installing the retracts was as simple and as painless as any retracts I had ever installed. Even the steps that are needed to secure the gear doors to the struts worked as advertised.

After mounting the wheels and axles to the struts and verifying that everything was lined up (proper toe-in angle of roughly 1°), the wing halves were finished.

Next up was installing the horizontal stabilizer. This was when I encountered the first problem. To measure and adjust the stabilizer, you must first attach the wing halves to the fuselage.

When sliding on each wing half, I found it impossible to line up the hole where the mounting bolt attaches. Some investigation found that the servo wires must pass through too small an opening. A few minutes with my rotary tool enlarged these openings on the fuselage and made it easier to get the wires inside without pinching them.

That was only part of the problem. I discovered that the wing bolts still wouldn’t install. More inspection showed that by making the holes slightly oval in the top of the fuselage’s bolt fixture, I could finally get the wing bolts to thread into the wing. This took some time because I didn’t want to remove any more than necessary. I trimmed a little, trial-fitted the parts, then trimmed some more until I got both halves to properly come together.

Now construction could continue by attaching the horizontal stabilizer. After verifying its alignment and trimming the excess covering, it is epoxied in place. After the epoxy has cured, the elevator halves and rudder are installed, as well as their corresponding control linkages.

Running the pushrods through the fuselage is a cinch because of the preinstalled support tubes, and there’s one for each elevator half, the rudder, and the tail wheel steering pushrods. There is a separate tail wheel cover included in case you choose to add an optional retractable tail wheel. That’s a nice touch!

It’s time for the powerplant installation. Three laser-cut plates are included with the kit (one for electric; one for a Saito four-stroke engine; and one for the Evolution 20cc). They lock on the firewall and can be used to drill the properly spaced mounting holes. This doesn’t work in the case of the Evolution’s mounting plate.

After drilling these holes and mounting the motor mount beams, I found that the beams were spaced too far apart—so much so that the motor was swimming in the space between the beams. I checked everything and found that the supplied template was wrong.

The P-47 is a good kit, but it had a flaw. The included 20cc mounting template has holes that are spaced too far apart. If drilled using this template, the beams will be roughly 0.5 inch too wide.

I removed the beams from the fuselage and set it aside for the evening. I came back the next day with some fresh eyes and decided that by working backward, I should be able to get the engine in the right spot. Working backward meant going through the steps to mount the cowl first.

With the cowl in position, I could use it to verify the other mounting measurements and slowly work the engine into the proper position by first mounting the Evolution 20 to the beams. I then needed to hold the fuselage vertically. To do this, I slid the wing tube in the fuselage and rested each end of the tube on a pair of high-backed chairs. They held the fuselage off of the ground and kept the firewall relatively horizontal.

I put the engine/mount assembly in place on the firewall and placed the cowl in position. Then it was simply a matter of taking my time and slowly moving the engine so that it was centered in the cowl opening. When I was happy with the position, I carefully removed the cowling and marked and drilled the correct holes to mount the beams. These properly spaced holes were roughly 1/2 inch narrower than those in the mounting template.

With that problem solved, the tank and its three-line fuel system were installed. Although black tubing was included, I opted to use Du-Bro Tygon tubing because I like to be able to see the fuel flow.

When attaching the tank, I found it strange that the manual instructs you to hold the tank with a rounded bottom in place on a flat surface. Instead, why not ensure that the tank won’t slide by utilizing the two pieces of triangle stock that are included for the electric motor installation? They’re not used and it’s easy to position them on each side of the tank and attach them to the floor with CA adhesive.

If you power the P-47 with a system that requires liquid, the author found it best to modify the tank mounts to help this rounded tank fit in a square hole. He recut an upper brace to match the curvature of the tank and used the included triangle stock to help support it on the shelf.

After hooking up the throttle servo, I placed the ignition battery and module under the tank floor then the receiver battery next to the tank. The receiver was positioned near the cockpit area on its own pad.

Removing the huge canopy/hatch reveals a cavernous area in which all of the radio and fueling gear fit. The batteries were mounted near the firewall for balance.

When I had finished installing everything, I set the throws and rates, glued the pilot in place, and attached the canopy. I then installed all of the other included scale details. Each wing has removable pylons—each with an attachable, but not droppable, bomb. Gun tips can be installed in the leading edge of each wing. Three exhaust ports can be glued in position and the (removable) top aerial antenna can be screwed in place.

When everything was assembled, I checked the center of gravity, which was on the aft end of the specified range. Because it was still within the range, I left it as it was.

Flying

As luck would have it, the first decent day that I had to maiden the P-47, there was enough crosswind at the field to make things interesting. After the obligatory ground shots and a warm-up of the engine, it was time to see if the P-47 handled as well in the air as Horizon Hobby claims.

Taxiing came first and the P-47 didn’t disappoint. There’s more than enough steering to maneuver on relatively smaller runways and the model is big and heavy enough that it won’t weathervane while taxiing.

Holding a touch of up-elevator to keep the tail wheel on the ground was just the ticket during the first takeoff. When at a good speed, the elevator was relaxed and the P-47 went straight down the runway and lifted off.

A few trim passes later, I was well into the pattern, doing low, high-speed passes for my photographer and having a ball doing it. When opening up the Evolution 20, the P-47 will really groove. Sure, it’s too quick to be a scale speed, but it was fun.

With the photos out of the way, I put the Thunderbolt through its paces—flying it like a warbird would fly. Rolls and loops looked great, if I do say so myself. Loops will naturally drop off in speed as you crest the top, and it takes a good amount of speed to perform a properly sized loop, just as it should.

More advanced maneuvers such as a Split-S, Immelmann turn, and half-Cuban turnarounds are smooth and really show off how well the P-47 handles. But it’s not all about big maneuvers; eventually you must land. To aid in this, the included flaps do a wonderful job of slowing the Thunderbolt and do so without a lot of ballooning if lowered at a scalelike speed.

I set the flaps up on a three-position switch and found that I never needed more than half flaps. Regardless of the flap setting, the Thunderbolt was completely controllable and showed no tendency to stall, which is rare for a warbird.

In Conclusion

I’ll be the first to admit that the P-47 was never one of my favorite warbird designs; however, Hangar 9’s 20cc P-47 has turned into one of my favorite airplanes to fly. It’s perfectly mated with the Evolution engine, which provides plenty of power and speed,
as well as 15-minute flight times.

The P-47’s wide flight envelope makes it a great dogfighter at speed, but a docile, controllable design when it comes to landing. It’s easy to transport to the field and is big enough to have a great presence in the air, but not so large that you need a truck and trailer to transport it.

If you’re in the market for a warbird, I strongly recommend that you check out this Hangar 9 offering. You’d be hard-pressed to find more bang for your buck in a size that’s just right for an average pilot.

—George Kaplan
flyingkaplan@yahoo.com

Manufacturer/Distributor:

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

Sources:

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

P-47D Thunderbolt manual

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

Written by Joe Hass
FF airplane returns as an RC model
Product Review
As seen in the June 2018 issue of Model Aviation.

Specifications

Wingspan: 20-3/16 inches
Wing area: 110.8 square inches
Flying weight: 5.6 to 6.75 ounces
Three channels: Rudder, elevator, and throttle
Price: $46.98

Pluses

• It is a complete kit.
• Propeller, motor, ESC, and servos are available directly from Retro RC.
• The airplane is totally cute.
• It is a quick build.

The Ebenezer is a gentle flier that can also be quite aerobatic. It can be flown indoors in larger venues such as a basketball court.

Bonus Video

Product Review

The Ebenezer was originally designed and published in the April 1958 edition of the British Aero Modeller magazine. (Yes it is spelled correctly. It is the Queen’s English.) It was an all-sheet wood, low-performance Free Flight (FF) model. Fast-forward 60 years, mix in laser cutting, micro RC equipment, LiPo batteries, and brushless motors, and you have the makings of a simple-to-build, fun project that can best be described as a Cartoon Scale flying machine. It flies well, indoors or out.

Thanks to Mark Freeland of Retro RC for finding this treasure and working through all of the details to create a fine kit. This is a great project if you are new to building and finishing with balsa wood. In addition to the 10-page instruction manual that is filled with pictures and text, there are detailed plans.

Two versions are available. The Limey is the British version with rounded wingtips. The Hun is the German version with scalloped trailing edges and a distinct resemblance to the Fokker D. VII. Jigs and fixtures that will help you with this and other construction projects are in the Retro RC catalog. A package that includes the propeller, motor, ESC, and 3.7-gram servos is also available from Retro RC.

The competed major assemblies are ready for finishing.

Construction starts with the wings—joining the center sections with each wing panel. Laser-cut hardwood and balsa parts make alignment easy. Simply make sure that you prop up each wing panel as directed to get the proper dihedral in all four panels.

Although I used CA glue, the recommended epoxy would make a more durable joint. Thin fiberglass on the joint will further reinforce the wing joints. A quick once-over with fine sandpaper smooths the surfaces and rounds the leading and trailing edges.

The fuselage is the most complicated, yet it is easy thanks to the laser cutting and instructions. The detailed manual is full of tips to make construction even easier. Resist the desire to sand anything until you are instructed to do so. Work begins with attaching the vertical stabilizer, top wing pylon, and balsa windshield. A neat technique for centering the items is included in the instructions.

Pylon reinforcements are added, along with firewall reinforcements that set the proper right thrust and downthrust. The firewall is assembled from three pieces of plywood that will eventually house the prebent landing gear. Epoxy is again the preferred adhesive to hold the firewall in place.

To gain enough room for the servos and receiver, balsa cheeks are added to each side of the basic fuselage. There is a specific left-side and right-side cheek. There is also a beautiful laser-cut, thin plywood hatch that is held in place with magnets. Thin CA is the preferred adhesive here. Aliphatic adhesives such as Titebond can work as well.

After the cheeks are completed and attached to the main fuselage, the upper and lower wing platforms are glued in place. The wings are attached with rubber bands. Dowels are supplied for both locations. Make sure you install the half dowels that hold the wings centered.

The included wheels are built up from a plywood core with balsa sides and plywood disks for the bearing surface. The wheels are cleverly built—actually glued—on a 1/16-inch drill bit to aid in alignment. When the bit is placed in a drill motor, you can sand the wheel to a pleasing shape. After mine were sanded, I pressed a sharpened #2 pencil into the wood to create a “tire” outline.

Wheels are easily constructed from laser-cut plywood and balsa. The “tire” is painted on.

Some black paint finished the tire section. The rest of the wheel was hand painted to match the airframe color. The completed wheels easily snap free from the drill then #2 O-rings hold the wheels centered on the landing gear.

Hinging the control surfaces is accomplished with the included thread in a figure-eight pattern through the laser-cut holes in each surface. This was how we created low-drag hinges in the early days of RC. Detailed instructions and pictures are included in the kit.

There are many options for finishing. You can leave the wood natural, use iron-on film, or paint it. I brushed on two coats of 50% thinned clear dope as a primer. I simply rubbed my hand over the surfaces to remove the roughness created by the first coats.

I then sprayed Testors Model Master olive drab from an aerosol can on all of the surfaces. A matched brush enamel finished the coloring and touched it up. A variety of brushed or sprayed paints will work. Test your finishing method on some scrap wood before putting the final application on your aircraft.

Decorations are included on a printed sheet of paper. Spray the top of the paper with hair spray to seal the toner then cut out the individual pieces and attach them with spray-on contact cement.

The removable wings make installing the servos and related linkages easy. The carbon-fiber pushrods have metal ends with Z bends to attach to the servo arms and control horns. Heat-shrink tubing holds everything together. After adjustments, a drop of thin CA under each piece of heat-shrink tubing locks everything in place.

Pushrods are made up of carbon-fiber rod, Z-bent wire, and heat-shrink tubing. It is easy to assemble and adjust. The model uses thread hinges with a figure-eight pattern.

I used an APC 6 x 4 electric propeller painted dark brown for a wood effect. The pilot figure was assembled, along with the included scarf, to complete the project.

The motor, battery, and servos are all easily accessible.

Normal-size fingers can easily mask the actual center of gravity (CG) location. Carefully check it. The CG is a laser-cut hole on the top wing pylon. Use sharpened #2 pencils, sharpened dowels, or chopsticks to suspend the aircraft on the CG. If needed, add weight to properly position the CG. Better yet, use a larger battery to extend flight times.

Resist any desire to increase the control throws beyond those recommended for the first flights. The rudder is surprisingly powerful. If your radio has mixing, consider mixing rudder to aileron to make it easier to fly, especially if you are accustomed to flying a four-channel aircraft and used to flying with rudder.

Takeoffs are straightforward. Smoothly advance the throttle. After the tail lifts off, add a touch of up-elevator to break ground. Indoors, I fly at half throttle. Horizontal and lazy eights are easy. For loops—more like a figure nine—I go to full throttle, dive a little, and pull up. Stalls are straight and more of a mush. It spins easily and recovers quickly.

This isn’t a 3D machine, but it can be extremely aerobatic. For rolls, go to high rate, full throttle, and pull up slightly as you apply full rudder. Rolls are barrel shaped. It is a lot of fun.

Work the throttle for landings, gradually reducing throttle and adding some up-elevator to flare. You can experiment with different propellers and control deflection to match your flying style. This is a draggy airframe, so don’t expect much of a glide if you chop the throttle completely.

This is a quick, fun build that will allow your creative juices to express themselves. Flying the Ebenezer is great, indoors or out. Keep it in the car for instant fun anywhere.

The completed model is derived from Bert Striegler’s Ebenezer, first published in the April 1958 issue of Aero Modeller magazine.

—Joe Hass
joehass@gmail.com

Manufacturer/Distributor:

Retro RC
(248) 212-9666
www.retrorc.us.com

Sources:

Testors Model Master
(800) 837-8677
www.testors.com

Written by Laddie Mikulasko
Build a 1930's Experimental Aircraft
Product Review
As seen in the June 2018 issue of Model Aviation.

Order Plans

Specifications

Model type: Semiscale
Skill level: Intermediate
Construction: Balsa and plywood
Wingspan: 60 inches
Length: 56 inches
Weight: 7 pounds, 4 ounces
Power system: Turnigy 3548 1,050 Kv brushless motor; 60-amp ESC; 4S 5,000 mAh battery; 11 x 6 APC propeller

On the ground, the model requires rudder correction. After it is in the air, the aircraft flies well and garners a lot of attention.

The full-scale Mauboussin M.40 Hémiptère was designed and built by a Frenchman, Pierre Maubossin. Its first flight was in 1935, but the project was abandoned in 1937 in order to concentrate on more conventional designs.

For most of my modeling life, I have been a big fan of unusual-looking airplanes. In 1989, I came across a drawing with three-views for the unique-looking Hémiptère. Shortly after that, I drew the plans for this model to be powered by a four-stroke glow engine. I built the model and I enjoyed flying it.

This time I decided to build a new, electric-powered model. I drew the plans and built it mostly out of 4 mm foam board.

However, when I started preparing the article for this magazine, I changed the drawings to use balsa, spruce, and plywood instead of foam. I did this because there are still numerous modelers who are more familiar building models using these materials rather than foam. The model can be powered with an electric 2826/10 300- to 500-watt outrunner or any similar motor.

Building the Wings

Build the front wing in two halves. Use 1/4-inch balsa sheet to cut out the full-depth leading edge (LE) spar, the main spar, and the rear spar. Cut out all of the ribs. The ribs are cut out in three sections: the LE, the middle section, and the rear section.

On the first three ribs, cut out 1/2-inch holes for the aileron extension cable. Using 3/32-inch balsa sheets, cut out the bottom LE sheeting and the trailing edge (TE) sheeting. Pin the sheets to the building board directly over the drawing.

Glue the bottom capstrips between the LE and TE sheeting then glue the main spars to the bottom LE sheeting followed by the rear spar to the bottom TE sheeting.

Glue all of the ribs to the bottom sheeting and spars and glue the LE spar to all of the ribs and to the bottom sheet. Glue the laminated wingtip to the wing.

Glue the top balsa LE sheeting to the ribs, to the LE spar, and to the main spar. Glue the top sheeting to the rear spar and ribs then all of the top capstrips to the ribs.

Separate the aileron from the wing and glue the aileron LE to it. Glue the hardwood blocks to the rib W1 and to the rear spar to hold the wing to the fuselage. The hardwood blocks are glued to ribs W2 and W3 to hold the main landing gear leg. Glue the 1/8-inch plywood plate that will hold the aileron servo.

Build the other half of the wing to the same stage. Pin the 3/32-inch bottom sheeting between the ribs W1. Position both wing halves so that the ribs W1 are sitting on this bottom sheeting. Place the shims under the ribs W7 to achieve the correct dihedral.

Now, you can glue the 1/8-inch plywood dihedral joiners to the back of the main spars and to the rear spar. Pull in the extension wire for the aileron servo. Insert and glue the hardwood dowel to the center of the wing. Glue the top sheeting over the ribs W1 and then you can sand the wing.

The doubler is glued to the side of the fuselage.

Building the Rear Wing

The rear wing is built in the same way as the front wing. Pull in the extension plugs for the elevator and the rudder servos. Glue the round end plates to the wingtips. You can opt to have this wing be removable or glue it to the fuselage.

Building the Fuselage

The fuselage is shown with all of the formers glued to the fuselage sides.

Cut out all of the formers, the fuselage sides, and the plywood doublers. Cut out all of the pieces for the motor firewall box. Glue these pieces to make the box, and then glue the firewall to the box. Depending on the length of the electric motor, the length of the box must be adjusted so that the propeller clears the cowl.

At this time, glue this box to the former F4, making sure that it is square with the former. Between the motor box sides and the former F4, glue the 1/2 x 1/2-inch balsa triangular stock. Glue the top and bottom longerons then the plywood doublers to the fuselage sides. Pin one side of the fuselage to the building board and glue the formers F4 to F8 to this side.

Make sure that the formers are square with the fuselage side—especially the former F4. Glue the other fuselage side to these formers. Stand the fuselage right side up and glue the top longerons to the formers. Glue the top sheeting to the formers and to the fuselage sides. Glue the bottom sheeting between F8 to F14.

Depending on the length of the electric motor, the length of the box must be adjusted so that the propeller clears the cowl.

After you make the cowl, note that it is held to the fuselage with four magnets. To the former F1, glue a preshaped balsa block. Inside the fuselage, glue two hardwood blocks for the wood screws that will hold the wing and one in the tail to support the tail wheel rod. Sand the fuselage and then cut out the cockpit.

Now you can glue the rear wing to the fuselage. Cover the model with your favorite material and install the servos and all of the controls. Check the center of gravity (CG) and if necessary, add lead to the nose to adjust the CG.

This servo controls the tail wheel and rudder.

At this point, the model is ready for its maiden flight.

Because the rudders are outside of the propeller blast, the model has a tendency to swing to the left. For this reason, hold the rudders to the right to counter the torque from the propeller. I found that the best way is to apply full power quickly so that the rudders are more effective.

In the air, the model behaves like a conventional airplane.

The author’s completed Mauboussin Hémiptère. The full-scale aircraft flew for the first time on April 25, 1935.

—Laddie Mikulasko
lmikulasko@cogeco.ca

Sources:

Turnigy Power Systems
www.turnigy.com