Piccolo wobble!

[Harry Spillett]

Hello folks,

My Piccolo seems to have developed a slow wobble around the mast a few
seconds after it lifts off. This gets worse and worse until you are forced
to land. I recently upgraded from the fixed pitch to the collective version
and this is when the wobble first appeared. I have tried a second set of
blades and the result is the same, any ideas what it may be?

Thanks,

Harry

[Chris Dugan]

"Harry Spillett" <harry.spillett@cadoganhall.com> wrote in message
news:dlakg0$7u0$1@nwrdmz03.dmz.ncs.ea.ibs-infra.bt.com...
> Hello folks,
>
> My Piccolo seems to have developed a slow wobble around the mast a few
> seconds after it lifts off. This gets worse and worse until you are forced
> to land. I recently upgraded from the fixed pitch to the collective
version
> and this is when the wobble first appeared. I have tried a second set of
> blades and the result is the same, any ideas what it may be?
>
> Thanks,
>
> Harry

Bent main shaft or flybar shaft?
Strip them both down and roll them each on a flat piece of glass to hear if
they make the tell tale snick snick sound. My flybar shaft was bent from new
but a gentle bit of pressure straightened it out.

Chris

[Beav]

"Harry Spillett" <harry.spillett@cadoganhall.com> wrote in message
news:dlakg0$7u0$1@nwrdmz03.dmz.ncs.ea.ibs-infra.bt.com...
> Hello folks,
>
> My Piccolo seems to have developed a slow wobble around the mast a few
> seconds after it lifts off. This gets worse and worse until you are forced
> to land. I recently upgraded from the fixed pitch to the collective
> version and this is when the wobble first appeared. I have tried a second
> set of blades and the result is the same, any ideas what it may be?


Rotor speed is too slow. You've gone from a fixed pitch Piccolo with a very
slow rotor, to a collective pitch, but I'm betting your head (your mind head
that is) is fixed on the original rotor speed, but with less area, the
collective pitch blades require a higher rotor speed.

There is another possible cause, although it's unlikely, but.... check it
anyway. The flybar/flybar carrier. If that's been somehow twisted so the
angle between the flybar and the main blades isn't 90 degrees, this can
cause the wobbles, but as I say, I think it's unlikely.


--
Beav

Reply to "beavis dot original at ntlworld dot com" (with the obvious
changes)

OMF#19

[Harry Spillett]

Thanks Beav,

I have set the head speed at 1650rpm but I have not had the head apart to
check the mast or flybar yet. I got this figure from the manual, do you
think this is correct or should it be faster than this?

H


"Beav" <beavis.original@ntlwoxoorld.com> wrote in message
news:11nhroepts9iv1f@news.supernews.com...
>
> "Harry Spillett" <harry.spillett@cadoganhall.com> wrote in message
> news:dlakg0$7u0$1@nwrdmz03.dmz.ncs.ea.ibs-infra.bt.com...
> > Hello folks,
> >
> > My Piccolo seems to have developed a slow wobble around the mast a few
> > seconds after it lifts off. This gets worse and worse until you are
forced
> > to land. I recently upgraded from the fixed pitch to the collective
> > version and this is when the wobble first appeared. I have tried a
second
> > set of blades and the result is the same, any ideas what it may be?
>
>
> Rotor speed is too slow. You've gone from a fixed pitch Piccolo with a
very
> slow rotor, to a collective pitch, but I'm betting your head (your mind
head
> that is) is fixed on the original rotor speed, but with less area, the
> collective pitch blades require a higher rotor speed.
>
> There is another possible cause, although it's unlikely, but.... check it
> anyway. The flybar/flybar carrier. If that's been somehow twisted so the
> angle between the flybar and the main blades isn't 90 degrees, this can
> cause the wobbles, but as I say, I think it's unlikely.
>
>
> --
> Beav
>
> Reply to "beavis dot original at ntlworld dot com" (with the obvious
> changes)
>
> OMF#19
>
>
>

[Beav]

"Harry Spillett" <harry.spillett@bigfoot.com> wrote in message
news:dldso2$fbl$1@newsg1.svr.pol.co.uk...
> Thanks Beav,
>
> I have set the head speed at 1650rpm but I have not had the head apart to
> check the mast or flybar yet. I got this figure from the manual, do you
> think this is correct or should it be faster than this?

It sounds pretty good Harry, but have you checked it's actually DOING those
revs? 1650 shouldn't have it wobbling.


--
Beav

Reply to "beavis dot original at ntlworld dot com" (with the obvious
changes)

OMF#19

[Harry Spillett]

Yep,

I set it up with a tacho and 1650 was the average reading. Will take the
head apart tonight to check for any nastiest.

H

> It sounds pretty good Harry, but have you checked it's actually DOING
> those revs? 1650 shouldn't have it wobbling.
>
>
> --
> Beav