Shadow (oz14483)

About this Plan

Shadow. Radio control duration model. Wingspan 57-1/4 in, wing area 356 sq in. For Cox Texaco .049 engine.

Quote: "RC Duration. A new way to fly.

In the 1988 AMA rulebook, a new and previously unknown way to fly models in competition was given form and substance as Provisional Event No702. The new event's name is RC Duration, or RCD, and the latest rules appear on the last page of the 1990/91 rulebook. Actually, the concept wasn't completely unknown. Many modelers will remember competing in 'Renaud Memorial' contests, and RCD is very similar.

All planes must be radio controlled and powered by a Cox .049 cu. in. reed valve engine with the standard 8cc tank. The only limit on engine run time is the fuel supply, and the maximum time per flight is 15 minutes. This arrangement will also sound familiar to SAM enthusiasts, as the power format is identical to their 1/2A Texaco rules, except for their seven-inch limit on propeller diameter.

Since the RCD concept has been developed with the so-called 'Sport Flier' in mind, aircraft specifications are simple and straightforward. Wingspan is limited to 60 inches, and the planes must weigh at least eight ounces per square foot of wing area. These specifications were adopted to limit the need for special materials and building techniques to be competitive, and to allow a wide variety of existing glider kits to qualify with very simple modifications. The minimum weight rule should result in stronger models using traditional materials and will eliminate the need for special lightweight radio systems. A standard two-channel radio is all that's needed for RC Duration flying.

Fuel economy, not brute power, is the key to success in duration events where engine runs are limited by a fuel allotment. Almost any 1-1/2 meter hand launched glider kit will work for RC Duration flying. Gnomes, Wristocrats, Cox Silhouettes, Flippers, Ace Hi's, Kastaways, Tercels and many others have been successfully converted by simply sawing off the nose, gluing on a 3/16-inch plywood firewall and mounting the engine with sheet metal screws.

Experimentation has shown that a wide variety of airframe shapes and sizes can provide good results, but the optimum wing area for RCD models will be in the 275 to 350 sq. in range. At 300 squares, the required weight is about 17 ounces, which is a good load for reed valve engines. Larger and heavier models can be flown, but will require higher rpm and therefore yield shorter engine runs; and a long run under power is one of the keys to success.

After a reasonable break-in period, the Cox Texaco .049 with a 7x6 prop will run dependably at 6000 rpm for about five minutes. That combination of power and run time will take a fairly clean, 18 ounce model as high as hawk meat. Black Widows and Golden Bees can be adjusted to match this performance but can also be cranky and inconsistent at reduced rpm... "

Direct submission to Outerzone.

Scan by MarkD, cleanup by Circlip.

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