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Subject:Re: Trim Tips
From:Andrew Puddifer
Date:Wed Aug 30 04:02:51 2000
I have heard of this before...I suspect its because the centre of pressure
moves back on the wing as speed increases(and a shallow dive may be the way to
reduce the angle of attack and therefore induced drag) and this rearward
movement of pressure allows less trim drag on the elevator(plane flies more
level in cruise).
Just my theory, I have thought about it a lot as you may have guessed!

Regards, Andrew.

Randall Becker wrote:

> I had an instructor once who swore up and down that the only way to approach
> book performance values in his Mooney was to do exactly what you suggest. He
> demonstrated that you couldnt get the plane up to normal cruising speed by
> just accelerating straight and level. You had to get there by descending
> slightly. No ones explained this effect to me from an aerodynamic
> standpoint, and I still think it may have been due to a rigging problem in
> his Mooney.
>
> "rip" wrote in message news:39AC5EF2.677E0E29@snet.net...
> > Thisll start a discussion! Climb slightly through your intended altitude,
> do a
> > preliminary trim, then let the airspeed increase to cruise as you descend
> to
> > your intended altitude and retrim. Try it, youll like it!
> >
> > Rip
> > Navion 5186K
> >
> > j wrote:
> >
> > > Sometimes when I reach cruise altitude I get the aircraft trimmed dead
> on
> > > the number Im after. Other times when I reach cruise altitude the
> same
> > > a/c ends up 200 higher than I want and end up fighting the plane
> endlessly.
> > > It seems like it is just stuck 200 higher than I want. This has
> happened
> > > more than once on a two leg trip; flight outbound is sweet, the return
> > > flight is more like a return fight.
> > >
> > > My CFI schooled me on pitch, power, trim. Does anyone have any handy
> tips
> > > on reaching a speedy & accurate trim? Or is it just gaining a feel for
> how
> > > much pressure should be dialed out by the trim wheel?
> > >
> > > Tips & helps greatly appreciated!
> > > Jack
> >




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