<VV> Radial Engine, not Rotary

[John Kepler]

"That was a radial engine..." 

Actually, according to my engineering books, the National Museum of the US
Air Force, and the National Air & Space Museum...that was a rotary engine.
A radial engine (use a P&W R-2800 as an example), has a rotating crank, not
a rotating engine!


"it seems an odd way to get  rotation to 
the propeller.  I am not sure what benefit there was to holding  the crank 
stationary and spinning the rest of the motor." 


It's quite simple actually, and gave an era of lousy fuel, inadequate
lubricants, and ambivalent metallurgy a rather impressive
horsepower-to-weight ratio engine that was also simple and (relatively)
reliable.  The point that you obviously don't know about these engines is
that they were two-strokes (somewhere in the TCM Archives, there are old WW
I flying movies that talk about the smell of castor oil in aircraft....the
height of two-stroke oil technology circa 1915).  The spinning engine acted
like a supercharger to evacuate combustion gasses via a single large exhaust
valve at the top of the cylinder and introduce the incoming fuel-air charge
via cylinder ports from the crankcase.

Yes, the gyro effect caused handling problems, but then, so did getting hit
by a pair of Spandau machineguns, "In aerial combat....speed is life!"  E.
Udet.

John