Follow-up to the December column
D.B. Mathews | [email protected]
The response to my wondering in the December issue whether anyone enjoyed my occasional efforts to describe unusual full‑scale prototypes elicited a huge response, all affirmative. The results have been satisfying; I’m humbled and challenged by the kind words sent by so many readers. My sincere thanks to all who responded with words of encouragement. I will do some more. Any nominees?
Since writing that column I have been fortunate to receive a much better three‑view of the Stearman‑Hammond and the Cessna "Magic Carpet." If you would like a copy, send an SASE (No. 10 business‑size envelope) to me at 909 N. Maize Rd., Wichita KS 67212. I cannot send them via e‑mail.
For some reason I insist on misspelling "Ercoupe," as Weldon Smith informs me. All my adult life I’ve thought the name had an "o" following the "r." Not only that, but I’ve been mispronouncing it as well. Thanks, Weldon.
Also included in this column:
- RC/CL "switch‑hitters"
- An ancient CL design converted to RC electric
- Thoughts on the effects of torque
- Jim Walker models
- New electric cells
RC/CL "switch‑hitters"
"Switch‑hitter" normally describes a baseball player who can bat right‑ or left‑handed. Keeping with that theme, here are some models converted from RC to CL and CL to electric‑powered RC.
Frank Wyatt of Jacksonville, Florida, is flying ordinary ARF RC scale models as CL models. He uses an old transmitter/receiver and servos to operate the retracts, throttle, and flaps on these models. It took me a few minutes to grasp what he was doing, and then it occurred to me that readers might find this concept of interest.
A handful of advanced CL scale modelers have used specialized, custom‑built transmitters strapped to their belts to operate functions in world‑class competition aircraft for several years. Frank, however, is flying sport CL using RC ARFs and old radio equipment at a greatly reduced investment and with much less complexity.
How he does it:
- He straps his old transmitter to his stomach with an old camera strap clipped into eyebolts in the transmitter case.
- He moves the appropriate sticks with his left hand while flying with the CL handle in his right hand.
- He leaves the transmitter antenna retracted; range is not a problem at about 70 feet and old AM systems are fine.
- He buys stock RC ARFs with built‑in retracts and flaps, adds a 1/4" plywood plate for a 4‑inch Brodak bellcrank, and runs .027 leadouts through tubing in the fuselage side and plywood wingtip guides. The servos are straight stock units.
Frank sent a video of the models flying; they perform like any kit‑built CL scale models. Innovation and inventiveness have been hallmarks of modelers throughout history, and this application certainly meets the criteria. I must mention that the use of any device broadcasting a radio‑frequency signal is illegal in an AMA CL contest, but this concept would be lots of fun for sport flying.
Ancient CL design converted to RC electric
On the other side of the plate: how about ancient CL designs flown via RC? Ed Solenberg of Santa Rosa, California, sent photos and details of a wonderful conversion project that will ring bells for some of us old‑timers.
Ed resurrected the Tethered Trainer from a November 1943 Air Trails and converted it to an electric‑powered RC model. This sort of thing has been done with Stanzel Sharks, and at one time Top Flite kitted an RC version of George Aldrich’s immortal Nobler. This conversion is notable because of the rarity and vintage of the prototype.
The Tethered Trainer, designed by Earl Cayton, was something of a breakthrough design in 1943, when CL models were often built from extremely strong, heavy balsa blocks. I presume those earliest published designs and kits were in many ways influenced by the Walker Fireball, which American Junior kitted just before World War II.
The Fireball featured a machined, solid‑balsa fuselage divided down the horizontal centerline to provide access to the ignition system and batteries, which were placed in a hollowed‑out interior. The wings were made from sheet balsa, top and bottom, over ribs, and the tail surfaces were solid sheet.
Jim Walker’s success probably led many designers to conclude sturdy—and therefore heavy—models were the way to go, a sort of rock‑on‑a‑string concept. The Tethered Trainer was a breakthrough in much lighter structures and used techniques familiar to free‑flight designers and builders: sheet‑balsa fuselage sides, former and stringer structure, and built‑up tail surfaces. The Trainer demonstrated that a CL model did not need to be built like a rock to fly well.
I remember being extremely attracted to the design when the construction article came out, but at the time I did not have a suitable engine. In those days the cost of a new engine was considerable compared to a carryout boy’s income (35¢ an hour). Not only that, no new engines were available in 1943 because of wartime shortages.
In 1946 Scientific Models picked up the Cayton design and kitted it as the "Cyclone." I did build one and recall it was a great flier on an O&R .23 engine on glow. Although the ad implied the Cyclone was suitable for a .60, it certainly would have been awful and terribly nose‑heavy with that power plant.
Ed lightened the design a bit and flies his with an E‑flite Park 370 Outrunner motor. Batteries are three Li‑Poly cells; the motor is 1080 Kv. The propeller is a 9 x 4.7 APC electric. Covering is a low‑heat film from Hobby Lobby called "Polycover." The overall weight is a mere 12.5 ounces.
Full‑size plans were available for many Air Trails designs back then from the magazine plans service for 25¢, as I recall. Plans for the Cyclone are now available through the AMA Plans Service as set 29252. Check the Web site for an astonishing list of FF, CL, and old RC designs.
Although designed more than 60 years ago, the Tethered Trainer/Cyclone has been converted into a terrific‑flying electric RC model—certainly not a use even remotely considered when it was new. One can only wonder how this concept might work with other old CL designs—an electric RC Chief, Madman, Zilch, etc.?
Thoughts on the effects of torque
Notice in pictures of CL models that some are set up to fly counterclockwise and others clockwise. What is that about?
In the early days of CL flying, many kits and magazine designs took advantage of the tendency of a motor/propeller’s torque to turn the model left, thus helping keep the lines tight. We lived in fear of a CL model losing line tension and consequently becoming uncontrollable. Many old CL fliers still prefer to fly clockwise as a result. I think the counterclockwise pattern became common when we learned to fly inverted, since upside down the lines tended to stay tighter. For left‑handed pilots, clockwise was also more comfortable.
When 1/2A Proto racing was introduced as an official AMA event for kids, Dale Kim made and sold left‑hand (reversed‑rotation) crankshafts for Cox Tee Dee engines. These and a reverse‑pitch propeller helped kids fly with tight lines even though they flew counterclockwise.
My left‑handed son Bruce flew his CL scale entries clockwise, which always caused a stir. Several times at the Nats someone began yelling that we were setting up on the wrong side of the circle. His method helped keep his lines tight, particularly on windy days.
All this pertains to two‑line systems. Stanzel Mono‑Line, a single line twisted for control, didn't need tight lines at all.
Those who fly RC models know their aircraft tend to turn left on takeoff, and most designs require right rudder early in the takeoff run—particularly taildraggers. The same thing is true with power free‑flight, where the launch pattern tends to go left. That is a result of the torque of the propeller's counterclockwise rotation. Torque compensation is also the reason why many RC designs need right thrust in the engine mount.
Jim Walker models
A‑J Models is the American Junior name used on the Jim Walker products. Frank Macy (http://americanjuniorclassics.com) has revived many Jim Walker designs, including the classic A‑J Interceptor and Hornet, and has them for sale. For those who don't know or have forgotten, the Interceptor was a folding‑wing, catapult‑launched glider and the Hornet was a wonderful flying, all‑wood, rubber‑powered model.
These models make wonderful gifts for youngsters (of any age). Many of us old guys learned much about trimming, balancing, and enjoying model airplanes with Interceptors. I've had a ball flying mine, and the darn things still are strongly attracted to trees even after 60 years. We and the trees have grown up and out (with a pure white top in my instance), but the fun remains.
Frank publishes a newsletter containing interesting photos and history. Go to his Web site for a real treat.
New electric cells
Lithium‑manganese (often referred to as "123") cells are being used in electric‑powered models. These are lower‑cost and safer units that are appearing in Black & Decker, Skil, and other manufacturers' cordless tools.
The cells' distributor currently charges the toolmakers approximately $4 per cell, but for hobby use they are more along the lines of $10 per cell. For good information and technical papers, go to www.fmadrirect.com and follow the links to 123 batteries.
Several advantages of these new cells:
- More energy per ounce
- Less chance of ignition if overcharged
- Potentially lower cost
I hope this column has shown you some ways to fly for fun.
MA
Transcribed from original scans by AI. Minor OCR errors may remain.
