Newbie needs advice?

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Paul Woodsford - 16 Apr 2005 21:18 GMT

I have just completed a Raptor 30 V2 from scratch and have finished setting
it up.
I tested it today , clamped to a test rig so it wouldn't go anywhere.
It started just fine , idled smoothly and picked up smoothly to 50% and then
100% throttle.
On closing the throttle there was a tail vibration at about 40% throttle
which was present with the gyro on Heading Hold but absent on normal
function. If I closed the throttle quickly to idle no vibration in either
mode, only if I slowly closed the throttle.
Does anyone have any idea what could be causing this?

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Chris Dugan - 16 Apr 2005 22:09 GMT

Yes it's called resonance or too high a gain on the gyro depending on whch
way the tail was vibrating. Vertical vibration (mainly showing up in the
tail feathers) means normal resonance in the airframe or a bent component
somewhere in the drivechain (mainshaft etc.) horizontal means the gyro was
hunting, you can cure the gyro by turning down the gain a touch but airframe
resonance needs other tuning methods mainly involving not revving it up to
full speed with blades attached whilst bolted to the ground.

Chris

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Paul Woodsford - 17 Apr 2005 11:10 GMT

Thanks Chris,
I thought it was the Gyro, thanks for confirming it.
I had Header Blades on to simulate the load and resistance of the proper
blades.

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Paul Woodsford
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> Yes it's called resonance or too high a gain on the gyro depending on whch
> way the tail was vibrating. Vertical vibration (mainly showing up in the
[quoted text clipped - 6 lines]
>
> Chris

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Model Forum / Radio Controlled / Helicopters / April 2005

Newbie needs advice?