Radio Control: Helicopters
Paul Tradelius, 6704 Santiago, Ft. Worth, TX 76133
ONE OF THE ASPECTS of helicopters that I really enjoy is that everything bolts together—there is little gluing or painting. There are times, however, when canopies, tail fins, fuselages, etc., need repairs, and until now fiberglass cloth and CyA (cyanoacrylate) has been the answer.
But recently, I noticed a piece of cloth-like fabric softener (a dryer sheet) my wife was using in the dryer, and tried a small repair job with it. It did the job just fine and was very easy to work with. It cuts straight and easily with a pair of scissors, is very light, and bonds well with CyA. I especially like using a sheet that has already been through the dryer, since it's free of the chemical softener.
My repair technique is to mate the broken parts first and apply a little baking soda to the area. Then I cut a piece of dryer sheet to size and lay it over the area to be repaired, adding a few drops of CyA over the area. The baking soda acts as both a kicker (to harden the CyA quickly) and a filler for the smaller cracks. Give it a try and let me know what you think—especially if you have an even better material to use for small repairs.
Last issue I talked about two new products shown at the last Toledo show: the JR XF622 radio and the Miniature Aircraft Gas X-Cell. I've had a chance to build and fly the Gas X-Cell and use the XF622 radio, and I am very impressed with both.
The Miniature Aircraft Gas X-Cell is a quality kit and pure pleasure to build. The complete instruction manual with blown-up diagrams and the numbered parts bag for each step made it easy to find the right part in the building sequence.
For those who have seen or built an X-Cell, there are no surprises in the design of the head, tail rotor, or servo tray. These are of the same proven design that has made the X-Cell a world champion helicopter.
I talked with Miniature Aircraft's Ted Schoonard to see if he had any plans for a metal head for the X-Cell. He said they experimented with such a design many years ago, but it did not give the X-Cell the feel they were looking for. Startup costs were actually less expensive to produce an all-metal head, but the composite head seemed to provide just enough flex for an extremely smooth hover platform, while still retaining full aerobatic capabilities.
But what's new with the Gas X-Cell is the graphite side-frame structure and the Zenoah 23 gas engine. There are actually two graphite modules—an upper one to hold the main mechanics and a lower one to hold the engine. These provide an extremely solid, yet lightweight structure to handle the increased engine size, while only adding about 1.5 pounds.
(I don't have a scale that weighs to a tenth of a pound in that weight range, but my bathroom scale shows the Gas X-Cell to weigh 12 pounds—about two pounds greater than my X-Cell .60.)
The only word of caution while building the Gas X-Cell has to do with the Zenoah engine. Before installation, disassemble the starter and flywheel and check the balance of the flywheel. Mine required several small holes drilled on the heavy side to balance it on a High Point.
Radio Equipment
I initially wanted to use the JR XF622 radio with the Gas X-Cell, but FM operation does not seem to be compatible with gas engines due to severe glitching problems. If someone knows a way to use FM on gas helis I would like to know the secret.
Initial Testing
Because I was unfamiliar with the Zenoah engine, I decided to remove the rotor blades and practice starting the engine, make some basic engine adjustments, and check overall control movement on the ground. It is certainly a pleasant engine to start in the field. With just a few quick pulls on the attached starter cord the Zenoah sprang to life with a very slow, smooth idle. I was very lucky I removed the rotor blades because I quickly found the FM glitching problem. When I gently ran the engine up with the rotor blades on, I'm sure there would have been some type of accident. I also tried several brands of FM receivers with the same glitching results. So I think if you want to fly gas, make sure you are using a PCM radio.
Flight Testing
Once I felt comfortable starting the engine and ensuring glitch-free operation of the radio, I bolted the rotor blades on and began engine break-in flights. From others' gas engine experience, I would recommend Evinrude outboard oil TC-W3. I initially used a 20:1 mixture for engine break-in. After a gallon or two the mixture can be reduced to 25:1. I leaned the main needle valve slightly during this process, which produced a noticeable increase in power.
I have flown several large-scale gas helicopters, and due to their lack of flight performance, I was not impressed. Put such thoughts behind you with the Gas X-Cell: The same steady X-Cell feel is there in a hover, but now this machine can really handle those strong Texas summer winds. Climbs out and overall aerobatic performance are again typical of the X-Cell... but now with a certain smoothness of raw power and low-end torque that is gentle on the ears and the fuel bill.
The Zenoah provides more than enough power for anything most of us care to do. Loops and rolls are almost as tight as with the X-Cell .60, while still retaining a very respectable inverted performance. Even autos are a snap with the long 690 mm weighted blades, but as always, be careful not to bleed off head speed too soon in the descent.
As you can probably tell, my impression of the Gas X-Cell is "two thumbs up." With the balanced flywheel, the engine/helicopter combination is extremely smooth and stable, and the sound of the Zenoah brings a whole new flying experience to helicopters.
As for the JR XF622, I installed it in my trusty ZX, and I am hard-pressed to find fault with a radio of this caliber that is priced the same as an entry-level heli radio.
The major flying features, which are only available on this entry-level radio, are separate throttle and pitch curves for autos, normal, and stunt flying. This means you can match a throttle and collective pitch curve for normal flying, yet optimize throttle and collective pitch again for autos and stunt flying.
The very small XF622 credit-card receiver is also nice for small electric or .30-size helicopters. It has the same (or better) specs than JR's larger receivers, yet it will fit almost anywhere.
With a 1,000 mAh airborne pack and five JR 507 servos, it represents a lot of value for the price. However, the 507 servos are not ball-bearing supported, so for any heavy helicopter work, it would be best to upgrade them to 517s or better.
As I write this column, the Nats is only a few short weeks away, and I'm looking forward to going to Lubbock, Texas to see all the fliers and their machines. Look for a full report in the next issue on who was flying what type of helicopter with what setup and engine, and what new products or setup ideas the rest of us can use in our flying.
Transcribed from original scans by AI. Minor OCR errors may remain.
