no-top-post wrote:
-- snip --

Otherwise the Wankel, besides having small size which allows a narrow
fuselage, has excellent power density and vibration free smoothness. The
Wankel is also remarkably reliable and trouble free. The lack of vibration
means that stuff doesn't crack, break or fall off the motor and things
nearby - - a major positive attribute as compared to most 2-strokes.

-- snip --

What are fuel consumption ratios for 4-stroke, 2-stroke, wankel;
and typical engine weight ratios ?

I expect the wankel to be lightest and thirstiest, so that up to
a certain duration threshold its combined engine + fuel is
better/lighter.

The 4 stroke piston engine is most fuel efficient, followed by the
rotary Wankel, and finally the 2 stroke piston engines; at least, for
the engines used in our gliders.

The Wankel has four phases (intake, compression, power, exhaust) like a
4 stroke piston engine, but "stroke" doesn't seem to apply to a rotary
engine! Maybe a good term is "4 phase"?

I don't know how the weights compare, but if you consider the entire
propulsion system (motor plus starter, muffler, etc, the mast and
propeller, fuel, pumps, lines, and fuel tanks, starting battery, engine
controls and wiring, and all the structural additions to a glider to
carry the motor, a few pounds variation in basic engine weights is
probably irrelevant.

--
Eric Greenwell - Washington State, USA
Change "netto" to "net" to email me directly

"Transponders in Sailplanes" on the Soaring Safety Foundation website
www.soaringsafety.org/prevention/articles.html

"A Guide to Self-launching Sailplane Operation" at www.motorglider.org