auwsome vid - Camel & Spit [Archive] - The Great Planes and warbirds Community

GregP

23rd July 2006, 10:40

Thanks Kitscha! Nice vid!

With modern semiconductor electronics, it should be possible to make a working throttle for the Rotary ... but that wouldn't be authentic! Still, it would make oepration a lot easier.

All you have to design is a variable duty ignition cutoff. Lind of similar to the circuits used to operate DC electric forklifts and similar devices.

Then again, anyone who actually would install the device would probably instal a modern engine to start with ... oh well.[8)]

montanamotor

24th July 2006, 05:52

Greg,

what, if I told you that, the problems with throttling back rotary engines would lie way beyond ignition hussles? Main and only reason, why you can't throttle back a running CLASSIC rotary engine, is the lack of flame-trapping wire-mesh in the induction elbows right before the cylinders.

Trust me. I know what I am talking about... As rotaries suck air-fuel-oil-mixture through the crankcase for lubrication-purposes, like any actual twostroke-engine still does - although rotaries are fourstrokes, of course! - any backfiring combustion in a cylinder, which is directly connected to the crankkase, would fire back into the crankcase, too - that is, as soon as you start trottling the engine back via a throttle-valve which might be installed in the fixed, hollow crankshaft-tube, throuch which ALL rotaries have to breathe through.

Guess, what a crankcase filled with one gallon of combustible fuel-air-mixture will do to a plane, if this mixture is being ignited by a backfiring cylinder? This will work more effectively in downing that very plane than Flak, I tell you.

Only the fast airflow at full throttle suppresses any tendency for a backfire sufficiently enough as to allow for an, at least kind-of-safe flight. But very low intake-manifold-pressure and hence, slow induction airflow (and of nothing else are we talking here, actually) is a pure invitation for an engine to backfire - especially for one, with a fixed ignition-timing, like those early rotaries were equipped with, also.

Therefore, the killswitch-throttle was introduced as a mere quickfix, to enable the pilot to at least partially - cylinder by cylinder - throttle back the power of the otherwise always running-full-bore rotary.

This flametrap-solution was detected in the early 20ies only, when the times for rotaries were over, anyway. Had the rotaries during the "Great War" had those wiremesh-flametraps in their intake-elbows already, they could have been throttled back as good as any other engine could be in those days.

But it wouldn't SOUND as good as it does in the end - would it...? :D

Cheers!

Montanamotor