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Where are all the twins?

This begins an exploration of one of the less-traveled aspects of our hobby. Many full-scale aircraft are multi-engined, but they're pretty rare as model airplanes. Many people would probably like to try them, but multi-engine planes present the typical modeler with a number of challenges: cramming engines, mufflers, fuel tanks and linkages into nacelles; building the wing extremely strong to support extra weight and vibration; the difficulty in matching and tuning multiple engine responses, and of course the one-engine-dies-on-takeoff nightmare.

Electric power replaces these challenges with easy solutions. Electric power simply enhances the realism of a twin. Glow twin models use larger than ``normal'' engines to make up for higher structural weight and to allow for a safety margin in the event of an engine failure. This creates high wing and power loadings, leading often to a ``frantic'', non-scale flight. Electrics have better weight distribution, no vibration, more efficient thrust and absolute reliability - which allows a lower-power twin system to give the same performance as a single engine aircraft. A well-designed electric twin will often come out substantially lighter than a glow model, and will subsequently fly ``more realistically'' and land slower than an equivalent glow plane. As an example, Keith Shaw's 1/6-scale 88'' deHavilland Comet weighs only 7.5 lbs, 3 lbs lighter than the glow version!



Craig Kulesa
Fri Dec 4 18:32:12 MST 1998