Chipsair Wackeltest

A scratch-built airplane for testing the OS 'Wankel' rotary engine.

Wingspan	150cm
Wing Area	34.5dm2
Airfoil	Eppler 197
Elevator	6.25dm2
Stabilizer	3dm2
Weight	1700g
Wing Loading	49g/dm2

A basic high-wing design with a slight old-timer look. Building started with the wing, using the E-197 outline printed with Profili. The rest was designed ad-hoc based on which pieces of wood happened to be available and what 'looked about right' with maybe a little inspiration from the DeHavilland Beaver to get the stabilizer outline and some 'round' windows on the side. Details of the front were determined after the rest of the plane was already covered to locate the engine such that the CG would be at 25% of the wing cord.

To reduce stress on the wankel engine, full-throttle runs are limited. In addition, the oil content of the fuel is raised by adding 2oz castor oil per gallon.

The plane flies great, like a trainer, but with more than enough power for vertical climb-out after takeoff. Most of the time I fly at 1/3 throttle. At full throttle it can flip and roll like crazy. On landings, it bounces easily if still at 'floating' speed.

KCRC Model-of-the-Month July 2010.