Re: 049 test stand dont's

I made a test stand to run in my OS Surpass .71 and .91 4 strokes. A
2' high wooden step ladder and some custom milled adjustable engine
mount rails. The .91 could fly the ladder if I let it. The ladder does
a good job of damping harmonics.
JR
Dweller in the cekllar
who had a large collection od Cox planes in his yout.

On Fri, 27 Jun 2008 20:00:23 -0700, Tim Wescott <tim@[EMAIL PROTECTED]
>
wrote:

>Got a Cox reed valve 049 engine going today, with a Davis head.
>
>For a motor stand I'm using a Tatone stand with a piece of 1/8" angle 
>iron on which the engine is bolted.
>
>Don't do this, unless you want some practical education in resonances. 
>At the 'bad frequency' (which was just a bit lower than what the engine 
>really wanted to do) I could see the cylinder moving through a 1/4" long 
>arc.
>
>Very disconcerting.
>
>But I could damp it out by hanging on to the engine, so I verified that 
>it runs (and smells) normally for a little Diesel conversion, and I have 
>the compression and mixture at a good setting to go on a plane.
>
>Tomorrow I go flying.
>
>Sometime soon I go get some nice thick T-bar and make a new test stand 
>adapter for 049s!
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