Radio Control: Scale
By Bob and Dolly Wischer
PARIS FAI MEETING
The annual trek to Paris for the FAI meeting on rules and technical specifications has finished and brought back some rather astonishing results.
For years U.S. competitors have complained that FAI model specifications were too restrictive, particularly the engine-displacement limit. It was generally agreed that the single .60 two-stroke engine in a Scale model was long since obsolete, yet the FAI rule book persisted with an upper limit originally imposed because of suspected unreliability of earlier radio equipment and for safety when models could be dangerous in novice hands. Some of those conditions may still exist, but the old restrictions are increasingly antiquated and were stifling competition.
Rule changes
Scale Subcommittee members concluded that engine size is not a truly limiting factor and agreed to eliminate engine-displacement limits from the FAI RC Scale rules effective January 1, 1988. The true limiting factor now is total flying weight (with dummy pilot but without fuel), which has been increased from six kilograms to seven kilograms (15.43 lb). For example, a seven-kilogram airplane with four engines each displacing three cubic inches would be impossible because the engines alone would exceed the weight limit.
Two other limits remain:
- Total horizontal area (wing plus stabilizer): increased to 250 square decimeters (26.9 sq ft).
- Maximum wing loading: 100 grams per square decimeter (32.77 oz per sq ft), based on the total horizontal area.
In practice, World Championship officials have typically accepted a competitor’s statement that the model meets specifications. Officially, model weight and area must be listed on the specification certificate and witnessed, in the U.S., by an AMA Contest Director.
Complexity and bonuses
Previously, strategically built models took full advantage of a generous complexity-bonus system. Although the system was widely reported to end in January 1988, the actual changeover date for U.S. contenders was July 1987 to accommodate the team selection program that precedes the Lincoln Nats.
Key bonus changes:
- Overall bonuses have been reduced so it is now unlikely anyone can reach the former 20% maximum.
- Multiengine models are generally held to a 15% bonus.
- An exception remains for tail-dragger triplanes, which carry a 20% bonus under the new schedule.
The revision is a compromise and will require further debate among national aero clubs. Complexity itself has hidden difficulties: very large, highly detailed multi-engine subjects may be so reduced in small detail that they become simple renditions, and those models often score poorly on static judging.
Attempts, timing, and on-board ignition
The "attempt" rule originally allowed a second chance to complete a flight in case of engine or radio trouble on the ground or within the first 60 seconds. With modern reliability, continued abuse of this rule (for example, calling an attempt to await better wind conditions) is no longer justified. The rule changes remove the attempt provision but compensate contestants by extending allowable preparation and flight times:
- Seven minutes from connection of the glow battery until takeoff.
- Fourteen minutes total flight time, plus one additional minute for each extra engine.
These revised times should reduce pressure to use expedients like in-model glow switches to preheat plugs.
New electronics
Joe Utasi of Jomar Products Corp. devised an On-Board Power Switch: a small circuit board (about 1 x 1½ in.) using a MOSFET that switches the glow plug on and off at a selected throttle-servo position. Features:
- Deactivates the glow-plug circuit if receiver or transmitter are switched off.
- Adjustable via a small potentiometer to set activation point in throttle travel.
- Load limit about 5 A without a heat sink (a Radio Shack heat sink can be added for higher loads, e.g., operating two glow plugs).
- Can be used as a separate receiver channel for switching applications (smoke pump, landing lights, video camera).
Jomar also offers a Solid State Battery Backer that automatically switches to a second battery pack when the main pack drops below a safe voltage. It requires carrying the extra four-cell pack but provides added safety for high-value Scale models.
Paris Hobby Show
Our visit to Paris coincided with the Paris Hobby Show at Exposition Park. Highlights and observations:
- The show was smaller and different in character than Toledo; admission was about $7 and the show was contained within a single large building.
- The standout RC Scale airplane was a McDonnell Douglas F-15 Eagle by Philip Auvruds (from Belgium), equipped with U.S.-made K&B TS5 engines and Turbax I fans. Overall, French modellers appeared reluctant to display many top-quality RC aircraft.
- An indoor enclosure hosted model helicopters flown on two-stroke engines and rubber-powered Peanut Scale models; retrieval from the surrounding coarse netting often required ladders and poles.
- Many exhibits were by hobby dealers rather than manufacturers; the new Kavan 55-lb-thrust gas turbine was notably absent.
- The largest portion of displays focused on radio-controlled surface vehicles (cars and trucks). A large serpentine race track drew much interest, with both two-stroke and electric cars. Highly detailed, engine-powered semi-trailer trucks (six to seven feet long) were on display.
- A live-steam model railroad (about 4.5–5 in gauge) occupied a large area; a radio-controlled freight train produced a noticeable pall of smoke.
- Compared directly with Toledo a few days later, U.S. Scale modelers are fortunate—many of the dozens of top-quality Scale models shown at Toledo would have been stars in Paris.
Judging and scoring
To lessen the effect of emotion and national bias in judging, new rules were adopted:
- The high and low flight scores for a contestant will be deleted to reduce bias and outlier influence.
- Flight scoring will be revised to average the two best flight scores, rewarding consistency. Previously, a single lucky flight under ideal conditions could decide a championship.
- It was suggested that flight judges be separated physically to avoid conversation and maintain independence.
World Championships are also strongly influenced by takeoff and landing maneuvers; accurate, consistent performance in these areas remains critical to success.
(End of article)
Transcribed from original scans by AI. Minor OCR errors may remain.
