JC's Planes and Projects

GWS Formosa glassed and powered with Mega brushless motor

Specifications:

Wingspan: 35.4 inches

Length: 35.9 inches

Wing area: 255 square inches (per GWS)

Weight: 15 ounces w/o battery, 21 ounces with 8-cell KAN 950s.

Transmitter: Futaba 8UAPS

Receiver: Hitec Electron 6-channel

Servos: 3 x Balsa Products “Bluebird” servos for full four-channel control. These are good, strong, and fast little servos. My only complaint is the short wires.

Power: Mega 16/15/5 brushless motor with TMM 18-3P controller. Batteries are 8-cell packs of Sanyo KR600AE, HEcell 1100 mah NiMH, or KAN 950s.

Prop: APC 7x5 E

Finish: Glassed with 0.56 ounce cloth and Minwax Polycrylic. Airbrushed with Pactra Racing Finish Acryls.

Features: Hitec antenna “bobbin” used to shorten antenna, Dubro spinner, and laser-cut Mega motor adapter to GWS stick mount from Ecubed RC.

I was intrigued with the “park pattern” concept that started taking root early in 2003. I had been flying my brushless Zagi like mad, but was wishing I had a rudder to explore more maneuvers. I had seen plans for the Jellybean speed-400 pattern plane on the Ezone and started building one. I got about halfway done and decided to purchase a Meridian from Old School R/C. I finished the Meridian, but it had lackluster performance on the s400 motor and I ended up flying it into a flight station pole and destroying it after only three flights. That was the end of s400 power for me. It is brushless from now on!

While I was fooling around with the Meridian and Jellybean, GWS released their entry into the park pattern arena with the Formosa. I ordered a Formosa from Horizon the same evening that I destroyed my Meridian. The kit is very reasonably priced and of very good quality. I knew that I would be modifying the kit to accept brushless power, but I also was curious about the use of fiberglass cloth and acrylic polyurethanes. I decided to glass it just to prove out the method.

The kit is easy to assemble. I made a few modifications and would, in retrospect, do some things differently. The list is not long:

1. I put too much of a bend in the elevator and rudder pushrod exit tubes. Be careful here and keep them as straight as possible. Also, I stepped down in wire diameter from the .040 supplied with the kit to .032 for better movement.

2. The battery compartment is too thin for the 2/3A cells that I will be using. I widened it to accommodate the extra thickness of these cells.

3. I would use ordinary wood glue or epoxy instead of the GWS glue.

4. I permanently affixed the canopy instead of making it removable. This adds rigidity, and the batteries are too big to go in through the canopy anyway.

5. I used a hot wire to carve away the middle foam member in the fuse to expose the battery mounting base. I extended the battery base with a balsa piece. The front part of the battery will tuck in under the ESC and switch. RX is attached with Velcro to the underside of the canopy. ESC tucks into the slot in the front of the fuse. On/off switch is mounted transversely with a small wire attached and poking out for easy arming and disarming. Access to the batteries is via the removable wing. See the photo below for an idea:

6. I used small nylon hinges on all surfaces and affixed them with Pacer hinge glue

7. I used a laser-cut GWS to Mega motor mount. These are the cat’s meow and are available from Ecubed RC. You can get your props and micro antenna’s there too. I have had excellent service from Ecubed.

8. I filled the landing gear, spar channel, and other cut-outs with light spackle and sanded smooth. I then glassed the entire airframe with .56 ounce glass cloth and one coat of Minwax Polycrylic. I just mixed up a “batter” of Polycrylic and baby talc and brushed it on to fill the weave. I then sanded it smooth. Yes, it does smell nice when you are sanding, but wear a mask anyway!

9. The entire airframe was airbrushed with Pactra Racing Finish Acryls. The acryls are water wash-up, dry fast, and don’t smell. The thinner is also harmless to the polyurethane base.

The glassing turned out very well. You have to look twice to realize that this is a foam airplane. The glassing adds significant structural rigidity, “ding” resistance, and of course weight. I am not sure how much weight is added by the glassing since the empty weight also reflects a heavier motor, spinner, RX, and ESC than stock.

I enjoyed the process of finishing this airframe the way I did. It would also be a great way to finish a GWS warbird if you went with brushless power to offset the weight. The RTF weight is the same as my Zagi and Ryan P-47 equipped with the same batteries so I know it will have ample power for pattern-type aerobatics. I am looking forward to getting it in the air.

Flying the Formosa

4/22/04 – Spring has sprung here in Michigan and I am finally able to test fly my new creations. The Formosa was number two in the test flight line up after the Yak-54. I charged up two HeCell packs and two KAN packs and headed to the field. The day of the test flight was not ideal with moderate strength 90-degree crosswinds. Initially, a HeCell pack was installed and a range check performed. Remember that I had used the Hitec antenna bobbin to reduce the size of the antenna down to 18 inches. The range check showed full range so I was ready to fly. I used a switch on my Futaba 8UAPS TX to mix-in some “up” elevator from the eighth channel dial. The dial adjusts the amount of elevator mixed in. The reason for having up elevator for launch is to keep the nose from diving until flying speed is reached. I had a friend do the initial launch. With the wind at our backs, we launched from mid-field at a 45-degree angle into the wind. Power as applied, the “high-sign” given, a quick step and a push, and the Formosa was off and climbing. I clicked the switch to remove the elevator mix and proceeded to feel the airplane out.

My first impression was that the airplane was very stable, tracked very well despite the wind, felt “light”, and was easy to turn and keep close. My setting for low-rate ailerons was too slow so I went to high-rates. My initial fears about making it too heavy were soon forgotten. The airframe carries the extra weight of the glassed finish and brushless power system very well. After some very minor trimming it was time to do some aerobatics. Aileron rolls were the first maneuver tried and they were very impressive – right on the axis. This airplane has the most axial rolls of any of my models! Four-point rolls were next and they were excellent. The Formosa will not maintain knife edge flight the way I have it set up, but it has sufficient authority during “top” rudder application on point rolls or rolling circles to maintain level flight. Loops, Cuban-8s, and hammer-heads were next and all were excellent. You can make the loops very large and the hammerheads towering before she runs out of steam. The Formosa has excellent, but limited vertical with the present power system.

The Formosa is not as fast as I had expected. I thought that it would be a bullet, but it isn’t. It will get going at a very good clip but the speed is not excessive. It is also very quiet. There is no gearbox noise like my Yak, or raspy prop “bark” like my Zagi. Just a pleasant hum as she powers by. Very relaxing!

After about 7 minutes of flight the TMM ESC started reducing power. This ESC does not have a hard cut-off. It just starts reducing power and that tells you to land. I cut the power and set up for a long flat glide in to landing. It was a crosswind landing but the Formosa handled it very well. Being very clean, it glides a long way. I brought it down to 2 feet and just held it off with elevator until it landed full-stall. Stall speed was surprisingly low and it will land nose-high with no sign of tip stall. Roll out, or skid-out in this case, is just slightly longer than a Zagi.

As of this flight report I have about two dozen flights on the Formosa. The Formosa tracks like an arrow making it very easy to trace elegant figures in the sky. It is a pleasant contrast to the 3D-optimized Yak-54. I have explored spins, snap-rolls, and tumbles and have found them to be very easy. I have pushed the flight envelope with full application of high-rate elevator at speed to bring about accelerated stall. I have found the onset of accelerated stall is slow and predictable – more gentle than my Zagi. The Formosa will do tight loops comfortably without snapping-out. Launching is a non-event – a flat-footed push is all it takes to get underway. Landings are just as comfortable. Like my Zagi, flying the Formosa is a stress-free and pleasant experience. I am very pleased with my Formosa project and can enthusiastically recommend it!

Additional Thoughts:

I find myself using a lot of throttle on the Formosa as I trace large aerobatic maneuvers. This has cut my flight times down to a typical 7 minutes. The TMM controller has a little to do with that because it will reduce power as opposed to cutting-off. I think that this is costing me a minute. The KANs clearly out-perform the HeCells in power output, but both are of similar duration. The real issue is that the Yak-54 has spoiled me with near 18-minute flights and I want to keep the Formosa up longer! I plan on experimenting with LiPos on this airframe in the future. Motocalc shows that very impressive power and duration is possible with a high-discharge 3s1p LiPo pack. LiPos will also reduce the RTF weight by about 2-ounces. I plan to experiment with these cells in the future.

Home