military-request@att.att.com (Bill Thacker) (10/27/89)
From: military-request@att.att.com (Bill Thacker) Again, numerous responses have been concatenated and trimmed. --- From: dyson@tut.cis.ohio-state.edu (mark l dyson) >[mod.note: I meant to mention this yesterday... isn't the correct > term "radial", not "rotary" ? My RX-7 has a rotary engine, > I thought A/C had radials. Or is a spinning radial also called > a rotary ? - Bill ] Your last assumption is the correct one, Bill. A radial engine is stationary, with a spinning crankshaft driven by radial cylinders. The rotaries, as you said above, were 'spinning radials.' The engine in your Mazda is misnamed (advertising being what it is today). It would be more properly called a 'rotary-piston' engine. Hope this answers your question. --- From: pierson@cimnet.dec.com (Dave Pierson) >[mod.note: I meant to mention this yesterday... isn't the correct > term "radial", not "rotary" ? Another case of "correct" varying with time. Until Wankel designed an engine for which a "simple" name was needed, the phrase "rotary engine" was used to refer to the WWI vintage a/c engines we have been discussing. The crankshaft was bolted to the a/c and the propeller was mounted to the crankcase. > My RX-7 has a rotary engine, I thought A/C had radials. "Radial" is the later, more conventional form, with the crankcase bolted to the a/c and the propeller on the crankshaft. --- From: Mike Tanner <tanner@tut.cis.ohio-state.edu> WWI rotaries had the cylinders arranged radially and the entire engine rotated. Like bolting the crankshaft of a normal radial to the firewall. In the modern Wankel-type rotary only the piston rotates, inside the "cylinder". (When I bought my Rx-7 I had to tell the state how many cylinders it's engine had. I was stumped until I found out that Ohio considers it to be four cylinders because there are two firing chambers for each of the two rotating pistons. I guess bureaucracy will find a way to fill in the boxes no matter what.) In any case, "rotary engine" is the term normally used for both types, WWI and Wankel. --- From: D Murphy <djm@castle.ed.ac.uk> The look of the engines when stationary is about the same, they both have the cylinders arranged radially from a central crankshaft. However, in the WWI aircraft, the crankshaft (!) was rigidly bolted to the airframe and the engine block to the propellor. The whole engine spun round the crankshaft - often causing cylinders to `shed', which was uncomfortable by all (surviving) accounts. The radial engines such as those used especially by the US aircraft (except the Mustang and I think the Airacobra) spun the crankshaft. Rotary engines in cars are more often called Wankel Engines, after their inventor, though I don't think that advertising this name would sell too many cars, especially to the young male market :-). They have a single rotating block which divides the combustion chamber into 3. Unfortunately I can't draw it on an ascii terminal.