Eric Miller wrote:
"David Hill" wrote

I'm working on a replica of a 1924 airplane originally powered by an
Indian Chief motorcycle engine. I've spent a year or two trying to find
a modern engine that somewhat resembles the Indian, and the best I have
come up with is a Harley-Davidson.


Do you really want your airplane to go "potato-potato-potato..." ? :-)

And on a more serious note, isn't the 45 degree configuration a lousy design
for vibration (or an excellent one, depending on how you look at it ) ?

Eric



Actually, I'd LOVE for my airplane to go "potato-potato-potato..."!
That's about the only think I like about a Harley. :-)

Yes, the 45 degree configuration is lousy regarding vibration (although
Honda has managed to smooth it out, just add 40 lbs or so of
counterweights). However, it's not as bad as the second engine that was
used in the original plane, the 28 hp Lawrance A-3 -- a two cylinder
opposed with a single crank throw, and no counterbalancing.

The buyer of the plane in 1926 commented on the excessive vibration in a
letter he write in the '80s. I know that in the late '20s someone came
up with a two throw crank conversion for these engines, but I only know
of one of these engines still running. And I'd rather fly behind a new
Harley engine than an 87 year old engine.

Interesting note on the Lawrance A-3 -- it does not have engine mounting
lugs. It has a grooved area around the base of each cylinder where you
*strap* the engine to the airplane. yikes!

--
David Hill
david at hillREMOVETHISfamily.org
Sautee-Nacoochee, GA, USA