Raptor 30v2 vibration at low rpm's after crash

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jj - 08 Sep 2006 05:25 GMT

I am new to the hobby and have a Raptor 30v2 that has developed large
vibrations at low rpm's (from idle to about half way to hovering) after
I repaired it from a crash (during my first time in the air). I
replaced the main blades, tail boom and flybar. The rest of the major
components seemed to be OK.

It is causing a ringing sound from the tail boom area at idle and a
little above with a very low frequency vibration. It sounds like a
metal against metal vibration. This goes away before getting to
hovering speed. Are there any suggestions as to what might be causing
this.

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Beav - 08 Sep 2006 22:56 GMT

>I am new to the hobby and have a Raptor 30v2 that has developed large
> vibrations at low rpm's (from idle to about half way to hovering) after
> I repaired it from a crash (during my first time in the air). I
> replaced the main blades, tail boom and flybar. The rest of the major
> components seemed to be OK.

If the blades were broken, the main spindle was bent too. (That's the steel
axle connecting the two blade holders) one of the biggest causes of
vibration on a heli is a bent spindle.

> It is causing a ringing sound from the tail boom area at idle and a
> little above with a very low frequency vibration. It sounds like a
> metal against metal vibration. This goes away before getting to
> hovering speed. Are there any suggestions as to what might be causing
> this.

Check the above, but also check the autorotation unit/belt drive area. A
metallic sound could be caused by the main shaft not being in exactly the
correct position too, so have a REALLY close look.

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Beav

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jj - 13 Sep 2006 08:46 GMT

Thanks,

I did a bit more messing around and found that the metallic ringing
sound was from the coupler on the tail control rod vibrating against
the tail shaft. I adjusted the guide to fix this. That still does not
solve the original problem of the vibrations occuring. It wouldn't be
the main spindle, as the vibrations occur even when holding the blades
at idle. I need to check the clutch, as I did burn out a clutch liner
earlier (before the crash) from a hot start and this might have caused
problems that are just now appearing. Is there an easy way to verify
that the clutch, fan, etc. are balanced?

Josh

> >I am new to the hobby and have a Raptor 30v2 that has developed large
> > vibrations at low rpm's (from idle to about half way to hovering) after
[quoted text clipped - 15 lines]
> metallic sound could be caused by the main shaft not being in exactly the
> correct position too, so have a REALLY close look.

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Beav - 16 Sep 2006 21:39 GMT

> Thanks,
>
[quoted text clipped - 7 lines]
> problems that are just now appearing. Is there an easy way to verify
> that the clutch, fan, etc. are balanced?

Only by putting the assembly on a Hi-Point balancer or similar, but they DO
need to be balanced to within a reasonable amount. Mind you, if they were
balanced before the crash and you not changed anything, they'll still BE
balanced. A clutch liner rarely causes an out of balance btw, but maybe this
"vibration" you're experiencing isn't a real world problem.

Engine/transmissions out of balance usually result in "buzzes" through the
machine, but nothing that would affect the flight characteristics (wobbles,
shakes etc)

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Beav

VN 750
Zed 1000
OMF# 19

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jj - 17 Sep 2006 05:04 GMT

Thanks,

It wobbles when it is on the ground, but appears to disappear once the
blades spin up, so this may not be much to worry about. I wasn't
really so much concerned about the clutch liner itself, but I was
worried that in the process of burning out the liner, I managed to
knock the metal clutch (I think I am using the right term, it's the
piece on the shaft that attaches to the engine) out of balance.

Josh

> > Thanks,
> >
[quoted text clipped - 17 lines]
> machine, but nothing that would affect the flight characteristics (wobbles,
> shakes etc)

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Beav - 18 Sep 2006 12:01 GMT

> Thanks,
>
> It wobbles when it is on the ground, but appears to disappear once the
> blades spin up, so this may not be much to worry about.

Those wobbles are usually associated with the blades not being in exactly
their correct position, but as this is because there's nothing holding them
in their correct position until rotor speed is "up there", it's not usually
a problem. Particularly if it disappears when the rotors ARE up to speed.

I wasn't

> really so much concerned about the clutch liner itself, but I was
> worried that in the process of burning out the liner, I managed to
> knock the metal clutch (I think I am using the right term, it's the
> piece on the shaft that attaches to the engine) out of balance.

It shouldn't have, unless you've half melted the f.cking thing.

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Beav

VN 750
Zed 1000
OMF# 19

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Model Forum / Radio Controlled / Helicopters / September 2006

Raptor 30v2 vibration at low rpm's after crash