flyrotary@lancaironline.net Mailing List Archive

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Rusty, another idea (maybe bad though...)

did you consider to run the PSRU without dampers? Even if you get a buzz or something like that you know that the dampers where the wrong ones....

Again, the "spectrum" analysis off the ACES might give you a starting point to run some numbers on the dampers.

Just don't ask me for the formulas - I haven't a clue - but there are smart people here that sure could crunch some, if you get them... numbers.

Thomas J.

----- Original Message -----

From: rijakits

To: Rotary motors in aircraft

Sent: Monday, January 16, 2006 4:27 PM

Subject: [FlyRotary] Re: shake, rattle and hum

Hi Rusty,

----- Original Message -----

From: Russell Duffy

To: Rotary motors in aircraft

Sent: Monday, January 16, 2006 12:58 AM

Subject: [FlyRotary] Re: shake, rattle and hum

You had made mention of the prop being set at a high pitch angle, and that you were going to reduce the pitch thinking that was part of the prop oscillation problem. Did you reset the pitch angle? If you did then apparently that was not the problem.

Hi Bob,

Yep, I changed the pitch from 15 degrees at the tip, to 10 degrees, and it made no difference.

Why not reduce more, go all the way to nearly flat pitch, from what I remember that prop is a little on the big side for the Kolb, isn't it.

Even if it doesn't produce any thrust (flat pitch), it works as a flywheel - At least you eleiminate ANY ( if there is...) stall issues at the tips....

FWIW You might give some thought to adding mass to the engine. This might be a situation where you could be adding weight to the wrong end of the vibration problem.

Adding mass would be like adding a heavy flywheel, or the missing rotor, but I'm not sure I follow how it could be adding weight to the "wrong end of the vibration problem."

And why don't you have that brandnew, easy to work with, etc. ACES on the machine, yet??

If I am not wrong you can measure any and everything with it! Even ceiling fans! Mine is down to 0.02 IPS :))

There is also a "spectrum" feature on it, to give you any resonante frequencies...

Vibrations are a bitch (on aircraft at least......), you might guess to the source based on what you "feel" - it might turn out to be a different source alltogether - the spectrum will help you chase the source. You also can set up to measure imbalance of the engine alone - Check wether you have all your counterweights clocked correctly...

What I say is: You HAVE a vibration analysis tool - and an easy to use one! Try it! Props is just one ofthe many uses!

I like the weather station, for some reason I thought it would be warmer in Florida :>)

Despite what many people believe, not all of Florida is in Miami. It's a big state, and we hide the best part in the panhandle. Shhhh, don't tell anyone :-)

21:56 1/15/06

I see you're with Bellsouth too :-)

Cheers,

Rusty

Thomas J.