REFLECTOR: Pitch Cycling (was Pitch Trim Mystery)

[Pat Shea]

I posted a query a while back about cycling. Flying
solo and trimmed for level flight, my XLRG has a
tendency to cycle in pitch. It can settle into 2
minute cycles with an amplitude of +/- 100'. With two
people up front this cycling tendency goes away. My CG
is comparable the most XL's. 

What's interesting is that the refecltor replies at
the time reported negative cycling. I've since spoken
to multiple fliers who do experience pitch cycling.
I'm still curious if anyone has been able to combat
this by means other than using the auto pilot or
adding ballast up front.

Pat 

--- John Dibble <aminetech at bluefrog.com> wrote:

> Scott,
> Thanks.  That helps a lot.  I was concerned about
> pitch stability because sometimes my
> S-TEC ap starts cycling, so I don't want to make it
> worse.  But if having the strainer
> inverted provides the same stability, then no
> problem.
> Any easy way to remove the strainer without
> incurring a lot of cosmetic work?
> 
> John
> 
> Scott Baker wrote:
> 
> > Hello John,
> > Removing the sparrow strainer will cause the pitch
> control motion to become
> > more sensitive - but not to the point of
> instability.
> > I'm not sure of the aircraft's behavior if the
> sparrow strainer were
> > reversed - thinking about it, the upward lifting
> of the strainer will lend
> > itself to favor nose pitch down - which left
> unchecked will result in
> > greater air speed - which gives more power to the
> sparrow strainer - which
> > causes the nose to pitch down some more --- I
> suppose at some point, the
> > pitch spring will halt this cycle of events.
> > SB


__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com