Written by Terry Dunn
A sport powered glider
As seen in the May 2017 issue of Model Aviation.
Model type: Aerobatic powered glider
Skill level: Intermediate
Wingspan: 60 inches
Wing area: 364 square inches
Length: 42.5 inches
Radio system: Tactic TTX850 2.4 GHz transmitter; Tactic TR625 receiver
Power system (included): 950 Kv outrunner brushless motor; 13.5 x 7 folding propeller; 40-amp ESC; four micro servos
Power output: 41.2 amps; 461 watts; 188 watts per pound
Flying weight: 2.5 pounds
Wing loading: 15.6 ounces per square foot
Components needed to complete: Four-plus-channel radio system; 3S 2,200 mAh LiPo battery and charger; basic assembly tools
Minimum flying area: Club field
Flight time: 6 to 7 minutes
• Quick assembly and durable construction.
• Slop-free control linkages.
• Strong climbs and smooth aerobatics.
• Aileron servos susceptible to damage.
The term powered glider can mean many things. For many of us, the category invokes images of docile, three-channel floaters with long, skinny wings, but there are also powered gliders that are capable of rocketlike climbs and spar-bending aerobatics. Flyzone’s new Rapide leans more toward the latter type. It has a powerful brushless motor, composite reinforcements, and four-channel control.
The Rapide is a Receiver-Ready (Rx-R) model with foam construction. A 950 Kv outrunner motor, 40-amp ESC, and four micro servos are factory installed. You must provide a four-plus-channel receiver and a compatible transmitter. You will also need a 3S 2,200 mAh LiPo flight battery. I used a Tactic TTX850 2.4 GHz transmitter, TR625 six-channel receiver, and an ElectriFly 3S 2,200 mAh 30C LiPo.
An ElectriFly 3S 2,200 mAh LiPo battery provides flight times averaging approximately six minutes. I added a hook-and-loop strap to securely hold the battery in place.
Unlike many gliders I’ve seen, you don’t need soft, fluffy mittens to handle the Rapide. It has surprisingly robust construction. The wing and horizontal stabilizer are both strengthened with integrated composite structures. The fuselage features molded-in plastic components to protect the nose and belly. Even the molded plastic canopy is a tough piece with a thick cross-section and molded-in ribs.
Overall, the build quality of the kit components is quite good. Most of the foam parts are smooth, with no visible mold marks. The graphics are all factory applied and my example had no apparent bubbles or wrinkles. I did find that some of the dark areas will bubble slightly when the airplane is left in direct sunlight.
The Rapide is an Rx-R model with nicely molded foam components and preapplied graphics.
A unique feature of the Rapide is its curved firewall. An adapter plate on the inside has a matching curved surface. To adjust the right thrust of the motor, you merely loosen the mounting screws and reset the adapter’s position along the firewall’s arc. It’s a clever arrangement. I was almost disappointed that the default setting required no tweaking.
A curved firewall permits thrust angle adjustments by loosening two screws.
Assembling the Rapide
Construction of the Rapide begins with the full-flying horizontal stabilizer. The hinge mechanism is simple and has almost no play. In fact, all of the control linkages throughout the model are notable for their precision. Even the Z-bend connections on the aileron pushrods have little slop.
The rudder and elevator servos are hidden beneath a plastic panel at the root of the vertical stabilizer. This results in pushrods that are short and rigid. The aileron pushrods are short as well. When you combine those factors, you have a precise control system. It’s probably the best control setup I’ve ever seen in a foam ARF.
The wing panels are removable. It takes some perseverance to get the wing roots fully seated into their sockets in the fuselage, but you will be rewarded with a solid connection between all of the components. A single screw inserted through the bottom of the fuselage keeps everything in place.
I deviated from the instructions when I configured the radio bay. Flyzone suggests placing the receiver on the starboard side of the fuselage, opposite the ESC. I typically prefer to separate the receiver and ESC as much as possible to mitigate any potential electronic noise issues.
I used hook-and-loop tape to mount the TR625 receiver to the roof of the inner fuselage, slightly ahead of the wing spar. It is a tight fit, but there is sufficient room for a tidy installation. I had to add a 3-inch servo extension to the ESC lead to be able to reach my alternate receiver location.
The kit includes a short Y harness for the aileron servos. I omitted this part and individually connected each servo to the receiver. This resulted in less wire, fewer physical connections, and the ability to trim each aileron independently. There is an additional benefit that I’ll mention later.
Self-adhesive hook-and-loop tape is provided to secure the battery. Most of the battery-mounting area has a tough plastic surface to where the tape’s adhesive sticks well. The rest of the battery area is bare foam, which was sure to delaminate the first time I tried to separate any hook-and-loop tape that was stuck there. My solution was to apply the self-adhesive tape only to the plastic area. That alone probably would have been sufficient, but I took an extra step to ensure that the battery would be secure.
The rudder and elevator servos are housed in the tail, resulting in short and strong linkages.
In the foam section of the battery mount, I added a hook-and-loop strap that wraps around the battery. The strap is bonded to the foam with GOOP adhesive. I further anchored the strap to the foam with plastic nails that go through the strap and deep into the foam. I used GOOP to hold the nails in place as well. My “nails” are actually plungers that were scavenged from discarded insulin syringes. Waste not, want not.
Flyzone includes a 13.5 x 7 folding propeller for the Rapide. Mine runs smoothly and requires no balancing. Two 3mm grub screws are provided to secure the aluminum propeller yoke to the motor shaft. I think that it’s much easier to apply torque with a screwdriver than a small hex wrench, so I substituted two 3mm x 5mm Phillips-head screws from my spare parts stash. Don’t forget to use threadlocker.
The screws used to attach the spinner to the yoke also require threadlocker. Instead of applying the liquid to the screws, I suggest that you use a pin to smear a small amount of threadlocker to the female threads of the yoke. The purpose of this unusual method is to avoid getting any threadlocker on the plastic spinner. My first spinner became brittle and crumbled in areas that had been contaminated with the threadlocker I used (Permatex Blue #24200). I’ve had no more problems since by keeping the plastic clean.
Flying the Rapide
The manual indicates an exceptionally wide center of gravity (CG) range for this model (30%-43% Mean Aerodynamic Chord). After numerous flights, I’ve settled on approximately 35% (25/8 inches behind the leading edge) as my preferred balance point. Experiment and see what suits you.
Launching the Rapide is easy. I am unable to get a good grip under the wing for a traditional overhand throw, so I prefer to grab the fuselage just behind the wing and use an underhand launch. The power system can lift the airplane vertically out of your hand if you want it to—simply power up and go.
How you fly the Rapide is up to you. You can certainly follow the classic path of a powered glider with a zoom climb, followed by a thermal-searching glide back down. This model has a great climb rate at full power. After you reach altitude and chop the throttle, the propeller will fold back to reduce drag.
Another alternative is to fly the Rapide like a sport airplane. It is fun just cruising around, even at low power settings. The airplane can carve its way through a wide range of four-channel aerobatics. There is plenty of power and control authority for loops and rolls. Even with high rates, these maneuvers are more graceful than snappy.
The Rapide is capable of sustained inverted flight, but it requires a healthy application of down-elevator. Less elevator is required with the CG positioned more rearward. The only maneuvers where this airplane struggles are those requiring a powerful rudder. My Hammerheads and stall turns are sloppy, and knife-edge flight is completely off the menu.
More often than not, I combine gliding and sport flying in the same hop. I might even push the Rapide through gliding aerobatics from time to time. It retains energy well. My favorite gliding maneuver is a quick vertical dive followed by a low, high-speed pass. It makes a great whistling sound as it flashes by.
With the motor shut down and the propeller folded back, the Flyzone Rapide Rx-R holds energy well. Keep this in mind when landing.
While reviewing some of the onboard video that I’ve recorded, I’ve noticed that the tail will sometimes flex during my high-speed dives. I haven’t detected any flutter, but I think it could be pushed to that point if you’re not careful, so I avoid power dives and any prolonged gliding dives.
Although the Rapide has an abundance of climbing power, it isn’t that fast in level flight when at full throttle. It gets around at a sporty, yet comfortable, speed. I suppose you could experiment with different propellers for more zip, but I am happy with the stock speed range.
Because the Rapide can be flown at such a wide range of throttle settings, its flight time is equally varied. I typically fly for 6 to 7 minutes and still have a reserve of power remaining. Your results will vary based on your particular flying style.
Landing the Rapide
Getting the Rapide back on the ground is not hard. Landing it precisely where you want, however, can be a challenge. Like many powered gliders with a folding propeller, the difficulty with landing is coaxing the airplane to slow down. It takes some planning to manage your energy and avoid overshooting the runway. One technique I’ve used with the Rapide is to put the airplane into a slip while on final approach. It requires a lot of rudder and just a hint of opposite aileron.
Flyzone offers a kit that allows you to add flaps to the Rapide’s wing. Instructions for this modification are outlined in the manual. The flaps would definitely help manage your landing approach, but they would also add weight and complexity to what is otherwise a delightfully simple airplane.
Rather than adding separate flaps, I used the TTX850’s programming options to configure the ailerons into flaperons and spoilerons. Because I had already independently connected the aileron servos to the receiver, I just had to input a few settings in the transmitter’s flap menu. It took less than 5 minutes.
I use a three-position switch to manage the flaperon movement. In the center position, the control surfaces are neutral and perform just as they did as pure ailerons. With the switch down, both ailerons drop 50% to act as flaps. This causes the nose to balloon up slightly, so I also mixed 10% down-elevator. In the uppermost position, the ailerons extend upward 50% to become spoilers.
Although I am still experimenting, I think I prefer using the spoiler option over flaps. The flaps are more effective at slowing the Rapide down, but the controls sometimes get mushy if I’m not careful. With spoilers deployed, the airplane doesn’t slow much, but the reduced wing lift prevents it from floating a long way.
Be mindful that the Rapide has little ground clearance below the wing. Inspect the aileron servos and hardware after each landing to ensure that nothing has been damaged. Better yet, make an effort to protect this vital gear. My Rapide will soon have a pair of servo fairings from Park Flyer Plastics.
Flyzone’s Rapide challenges the common notion of what a powered glider should be. Not only does it fit the traditional climb-and-glide profile, it has impressive aerobatic chops. This airplane is powerful and rugged. Most of all, it is fun to fly … and that’s the only category that really matters!
Park Flyer Plastics