Boris Beizer wrote:


It is a compressed gas starter. A shell .. looks like a shotgun shell.. is
fired which provides the compressed gas that is used to turn the engine
over. It was, I believe, used as an emergency starting method for older
radial engines.

I don't think it was compressed gas. It was gun powder of some form.
Used on a numer of aircraft engines, not all of them radials (I know early
models of the Rolls Royce Griffon engine used them). I'm also pretty sure
that for some planes (Grumman Hellcat, IIRC) it was the normal way of
starting tme.


--
Frank Stutzman
Bonanza N494B "Hula Girl"
Hood River, OR