Radio Control: Scale
Bob & Dolly Wischer
FAI rules proposals
The agenda for the 1982 FAI plenary session in Paris contained no surprises except for the absence of any national proposal to increase the model weight limit above the present 6 kg (13.2 lb) without fuel. There had been considerable agitation in the U.S. for an increase, yet no one made an official proposal. We must assume, from this absence of action, that most are satisfied with the 13.2 lb limit. (A magazine columnist recently—December 1982—called the limit 11 lb.) We have now flown two World Championships at 13 lb. A couple of 1982 Reno entries were slightly overweight and required removal of some superfluous internal parts to reach the limit, but the restriction seems to have imposed no real hardship.
The expected clamor for larger engine displacements also didn't materialize as formal rule proposals. Switzerland asked that four-stroke engine displacement for Scale models be brought into line with the current allowable size for Pattern airplanes, which permits 20 cc (1.22 cu in). The Swiss proposal also asked for a 40 cc total limit for four-stroke multi‑engined models. A change to 20 cc for four‑stroke, single‑engine models could have been enacted in 1981 except that the agenda item specified only 15 cc. (The Scale subcommittee is obligated to vote only on what is actually on the agenda; members cannot change proposals at the meeting, and voting is carried out on each item as written.) The 1982 agenda contained no Scale proposals from the U.S.
The most sweeping change proposed concerned combining Precision and Sport Scale into a single event. The reason was a worldwide lack of interest in Precision Scale competition. At the Reno World Championship the two classes' models looked alike; one needed to read the place cards on exhibition tables to determine the entered class. Under the proposed rules, static judging would be done from 3 meters (10 ft) distance, with details judged separately from 1 meter (39 in.). Measurements and the scale ruler would be eliminated.
Twin problems
Our first twin, the Douglas A-20G Havoc, convinced us of the need for a practice model with flight characteristics similar to the Douglas. We have kept at least one non-scale, single-engine trainer in readiness for sessions; it is flown about 10 hours for every hour of the Scale planes. We prefer that it not be too forgiving. Flying a model that requires constant attention helps develop skills useful for heavy, detail-laden Scale models. If the trainer has too light a wing loading, it teaches nothing about handling Scale planes. The trainer's greatest value is for practicing takeoffs and landings with endless touch-and-go routines to sharpen reflexes.
Initially we regarded the twin-engined Douglas as "just another airplane," despite the high time and effort in construction. After several post-accident reassemblies, we concluded a twin trainer is desirable—preferably one with essentially similar wing loading and flight habits to the twin Scale model. The need became apparent when a friend with a similar model experienced almost identical landing-approach problems. Scale twins tend to be heavy—probably more so than single-engine types. They are a joy to fly, even though heavy, but landings and slow flight can be a pain: they tend to glide like the proverbial streamlined brick.
After establishing the glide angle and as the model nears touchdown, a slight touch of up-elevator often fails to produce the usual rounding into a flare. Instead, the model crashes onto the runway, destroying retractable nose gear and possibly causing large structural damage. The cause? Too slow an approach with throttle near idle. Up-elevator intended to produce a flare merely stalled the wing; the rate of descent was not slowed and application of elevator may have accelerated the descent.
There can be a brief apparent flare, similar to what happens in a pull-up or a turn where elevator is used to maintain altitude. In those maneuvers up-elevator adds centrifugal force to the model's weight (gravity) because the flight path is curved. Near touchdown the two forces combined may exceed what the slow-moving wing can lift, so the model continues its descent into the runway even though the nose is up. The amount of elevator travel is inconsequential—lack of flying speed caused the accident: a slow-speed stall. More elevator travel would not have saved the model. An airplane with high wing loading needs to be flown down to the surface, not glided like a light trainer, and this requires throttle to be near mid-position; throttle can be closed just before or after touchdown. The situation can be considerably improved by keeping weight down during construction.
At full throttle in a 45° bank, with up-elevator applied to avoid altitude loss, a 12 lb model plus G forces increases the load on the wing to about 24 lb, and this happens at the model's top speed. This describes a classic high-speed stall. The wing's angle of attack must be increased with up-elevator to generate enough lift to support the airplane's weight multiplied by centrifugal force in the turn. At high angle of attack the wing will stall. High G forces, combined with high angle of attack, precipitate the high-speed stall. A full-size Spitfire, for example, could stall and spin out of a steep turn at 250 mph. Performing a steep turn to low altitude with a heavy model is an invitation to disaster.
Information-seekers
Most of our correspondence consists of requests for prototype aircraft information, with a secondary number asking for construction ideas. The first group tells us of the large number of Scale projects under way, many of which are models of rare aircraft being undertaken by diligent modelers. Often their research makes them the solitary experts on their chosen prototype. In order to design and build a model they may gather more construction and historical information than has been available since the craft was built.
Two examples:
- Bob Lobpraske spent two years gathering data on the Focke‑Wulf Fw 56 Stösser, using all available sources including the factory. After weeding out misinformation and producing correct drawings for RCM&E, Bob now finds himself the leading authority on the plane.
- Dave Reid researched the Kinner Sportster and, after finding one of the rare originals 100 miles from home, produced a set of drawings for a quarter-scale model. (DGA Designs, 135 E. Main St., Phelps, NY 14532.) Dave requests a stamped envelope.
All of the above—home-drawn three-views, photo enlargements or negatives, and rare documentation—may be more valuable than the modeler suspects. Museums are very grateful to receive such data, and they place a dollar value on it that can be used as a tax deduction by the donor.
A plea: if you're working on an unusual Scale project, please drop us a line. We'll help as best we can and, if we can't, we'll point you in the right direction.
Classic and antique reproductions
Next in the line of classic and antique reproductions was a World War I German fighter, the Siemens-Schuckert D.IV, built by Carl Swanson. Carl is also the builder of the Sopwith Triplane and Nieuport 17 in the Canadian National Collection at Ottawa. He had somehow found an original Siemens‑Halske rotary engine which, like most rotaries, had no throttle. Carl taxied the Schuckert by cutting off ignition on all but one of its cylinders. The plane was sold to a Swiss museum that wanted it because of its rare engine.
Homebuilts and Oshkosh
Homebuilts are the nucleus of show planes at Oshkosh and almost all of the 500+ homebuilts would adapt easily as modeling subjects. Of the top five most common at Oshkosh, only one has enjoyed widespread modeling popularity:
- Rutan VariEze (63 present)
- Thorp T-18
- Christen Eagle (popular as a model)
- Monnett Sonerai II
- Wittman Tailwind
Close behind those were Pitts and Skybolt—two commonly modeled homebuilts—with 38 examples of those two types present.
Modelers looking for different examples of a Mustang or AT-6 would have found about 70 combined. Also present were:
- Boeing B-29
- Consolidated B-24 Liberator
- three Boeing B-17s
- two B-25 Mitchells
- three P-38 Lightnings
- four Hawker Sea Furys
- various Bearcats, Hellcats, Wildcats, Corsairs and an Avenger
- a rare Russian Yakolev Yak C-11 (equivalent to the AT-6) that performed in the airshows
An AMA membership card and a small fee will get a flight line pass for close-up photos needed to complete a model. The pass also permits front-row seats for afternoon airshows where, on certain days, almost all of the military heavy iron is flown. Interior photos without permission from individual owners are forbidden, as is touching a plane. Owners are usually flattered that a modeler wants details for a model. Serious modelers have donated printed material and models to museums; museums then provide a letter stating the donated items' appraised value for tax purposes. Donations should contain detailed research with good photos and drawings of airplanes not already well documented.
Information source — Oshkosh
Nowhere on earth is there an information-seeker's paradise to compare with Oshkosh during the Experimental Aircraft Association annual convention (which, unfortunately, often coincides with the Nats). The 1982 gathering brought together many aircraft types that delight Scale modelers. Jim Younkin's Mr. Mulligan reproduction made its first appearance and was instantly the center of attention. It is an accurate, full-size copy of Benny Howard's DGA-6 in every respect, from its 650 hp Pratt & Whitney engine to the odd, non-retractable tailwheel. Notable were the modeler's sources of information Jim used to design and build the plane, including Paul Matt's Historical Aviation Album and drawings from Cleveland Model and Supply. As Jim had done for his earlier Travel Air Mystery Ship, photos were used to verify shape and locations of details—much as we do for a model.
Transcribed from original scans by AI. Minor OCR errors may remain.
