Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!att!cbnews!military
From: cperlebe@encad.Wichita.NCR.COM (Chris Perleberg)
Newsgroups: sci.military
Subject: Re: Rotary engine airplane troubles
Message-ID: <10715@cbnews.ATT.COM>
Date: 28 Oct 89 04:21:58 GMT
References: <10577@cbnews.ATT.COM> <10622@cbnews.ATT.COM>
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From: cperlebe@encad.Wichita.NCR.COM (Chris Perleberg)

In article <10622@cbnews.ATT.COM> dyson@tut.cis.ohio-state.edu (mark l dyson) writes:
>
>
>From: dyson@tut.cis.ohio-state.edu (mark l dyson)
>
>In article <10577@cbnews.ATT.COM> entropy@pawl.rpi.edu (Speaker for the Clams) writes:
>
>>	I've heard that some early WWI aircraft such as the
>>Fokker DR1 and Sopwith Pup were designed so that the engine
>>was fixed to the propeller shaft and the entire engine spun
>>round and round within the fuselage.
>
>[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 ]
>

No, the term rotary is correct.  There were no radial engines (engines 
where the prop shaft spun while the engine remained stationary) in the 
Great War (the 1918 Siemens-Schukert D-VI? may have had a radial -- 
memory fails me -- but I doubt it).  All "round" engines in the First 
War were rotaries.  The last major fighters produced by both the 
British and Germans in 1918 (the Sopwith Snipe and the Fokker D-VIII) 
had rotary engines (the French SPAD series had inline engines, as did 
the Fokker D-VII and SE-5a).  

Not all aircraft with rotary engines shared the turning 
characteristics of the Sopwith Camel or Fokker Triplane.  In fact, 
most didn't.  The determining factors must have been plane size, 
engine power, wing-loading and so on (I'm not an aircraft engineer).  
Some rotaries, like the FE2 or DH2 pushers, gained almost no 
maneuverability from the engine (they were dogs, in fact).  Others, 
like the Nieuport series and the Sopwith Pup, gained a little, but not 
much.  Other design factors made them maneuverable.

The rotary had its disadvantages.  First, as engines got bigger and 
bigger, more and more metal got slung around, reducing efficiency.  
Second, damage to the prop or engine (like a cylinder breaking off) 
could unbalance the engine (no kidding), and make the whole aircraft 
fall apart (extremely unpleasant in the days before parachutes 8-).  
This was especially a problem in the early days of interrupter gear 
(the gearing that linked the propeller with the MG trigger so that the 
MG could fire safely through the prop).  Max Immelmann (inventor of 
the "Immelmann turn") is thought to have shot himself down in 1916 
when the interrupter gear on his Fokker E-IV "slipped" a bit and shot 
his propeller off.


Chris Perleberg
cperlebe@encad.wichita.ncr.com