Ron Wanttaja wrote:
On Tue, 21 Oct 2003 14:47:32 GMT, David Hill
wrote:

The project I'm working on (1924 Epps Light Monoplane replica) motivated
me to learn about modern motorcycle engines. The original engine in the
original plane was an Indian Chief motorcycle engine.
snip
At some point before the plane was sold, it was converted to a Lawrance
A-3 engine. I've heard two stories about why he changed the engine.
One is that he wanted more power (28 hp for the Lawrance vs. 17 hp for
the Indian). The other story is that he got tired of the chain breaking.

Hey, cool. But forget those period motorcycle engines. Use a nice
reliable aircraft engine, like a Szekely. :-)

(For those who don't get it: The Szekely 3-cylinder radial has an AD note
calling for a cable running around the outside of the cylinders. To
prevent the parts from flying too far away when they break....)

The Lawrance engine wasn't much better than the Szekely; it actually was
not that much of an improvement over the bike engine. For those not
familiar with it, I think of it as a 2 cylinder radial. It had two
opposing pistons connecting to one crankshaft throw. And as far as I
have been able to determine, no counterweights. That's a lot of mass
being thrown back and forth in synchronization.

The fellow who bought the plane with the Lawrance engine installed
recalled (in 1985 or so) that the engine vibrated terribly. And in fact
the plane was demolished when the engine quit one day with Paul Rizzo
flying it.

The biggest surprise I got regarding the Lawrance engine, once I saw one
up close and in person, is no engine mounts! Just a groove around the
base of each cylinder to facilitate strapping it to the airplane!

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

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