REFLECTOR: Pitch Trim Mystery
John Dibble
aminetech at bluefrog.com
Thu Feb 16 15:55:36 CST 2006
I think the need for down trim is just a function of cg and speed. Since I'm at my
aft cg limit (actually beyond the limit according to the standard Velocity
calculations), I will need more trim than if I was not so aft cg. My guess is I have
about 2" elevator up at cruise.
John
Alex Balic wrote:
> Hmmm, Well, probably a good idea to keep the incidence as is then, but I
> think that it is a bit unusual for you to need so much down trim in cruise-
> maybe a smaller/no strainer would work best for you- how much actual up
> elevator do you have at top cruise?
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of John Dibble
> Sent: Thursday, February 16, 2006 1:19 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Pitch Trim Mystery
>
> Alex,
> Thanks, but when solo, my canard barely stalls, more like a mush. I'm
> concerned that
> less incidence might put me in the deep stall mode. Besides, the weight is
> just a
> temporary thing anyway. I'm currently getting 180-182kn with my Franklin/IVO
> and I
> hope to get a few kn more once the trim issue is resolved and I can use full
> power.
>
> Alex Balic wrote:
>
> > John-
> > In lieu of adding the weight- you might think about dropping the canard
> > incidence about a degree- will give you more speed too...
> >
> > Alex
> >
> > -----Original Message-----
> > From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> > Behalf Of John Dibble
> > Sent: Thursday, February 16, 2006 12:09 PM
> > To: Velocity Aircraft Owners and Builders list
> > Subject: Re: REFLECTOR: Pitch Trim Mystery
> >
> > Steve,
> > I have one installed. I need to check, but I believe it wroks against the
> > spring, so
> > I guess I need to reverse it. How much work is involved to do that?
> >
> > Scott B - I believe you mentioned that reversing the strainer could cause
> > instability. How can I flight test for this?
> >
> > In the meantime, I plan to add 20lb to the nose, so I won't have to use
> the
> > full trim
> > adjustment at cruise.
> >
> > John
> >
> > steve korney wrote:
> >
> > > A lite spring and a external trim tab would solve that problem.....
> Like
> > a
> > > sparrow strainer
> > >
> > > Best... Steve
> > >
> > > ----Original Message Follows----
> > > From: John Dibble <aminetech at bluefrog.com>
> > > Reply-To: Velocity Aircraft Owners and Builders list
> <reflector at tvbf.org>
> > > To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
> > > Subject: Re: REFLECTOR: Pitch Trim Mystery
> > > Date: Wed, 15 Feb 2006 11:28:10 -0600
> > >
> > > Well, that sounds like a good guess. For the entire flight either the
> > > autopilot or
> > > myself was adding a little extra pressure to maintain level flight.
> After
> > I
> > > got out
> > > of the plane I pushed down on the elevator a little. Maybe that is what
> > > made it work
> > > again. I'll check it out. But wouldn't pulling back on the stick also
> do
> > > the same
> > > thing? Or am I not understanding this right?
> > >
> > > Scott - It took a lot of force and of course the farther I pulled back,
> > the
> > > stronger
> > > the force. It felt like I might break something. I suppose you could
> > trim
> > > your
> > > elevator all the way up and feel the force to pull the stick back to
> > > neutral.
> > >
> > > John
> > >
> > > Alex Balic wrote:
> > >
> > > > The pitch trim jack screw has an internal "switch" that turns it off
> in
> > > the
> > > > particular direction of travel that would bottom it out- possibly
> this
> > is
> > > > just slightly out or the contact is burned, hard to tell- not sure if
> > you
> > > > could even open it up to check that - you might want to do some
> > > > experimenting- see if you run it all of the way to the bottom and you
> > > force
> > > > it if it might move just a bit more and loose contact internally,
> after
> > > > relieving pressure, apply pressure in the opposite direction- might
> > move
> > > > back just a tiny bit to regain contact again- just a guess......
> > > >
> > > > -----Original Message-----
> > > > From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
> On
> > > > Behalf Of John Dibble
> > > > Sent: Wednesday, February 15, 2006 10:46 AM
> > > > To: Velocity Aircraft Owners and Builders list
> > > > Subject: REFLECTOR: Pitch Trim Mystery
> > > >
> > > > Seems like when the Reflector has a what-if discussion, soon after
> > > someone
> > > > has to go
> > > > out and experience it. I guess the pitch trim failure had my name on
> > it.
> > > > Last night
> > > > I flew 1.7 hrs at 180 kn with the pitch trim pegged at down trim. I
> > cut
> > > > power just
> > > > enough to descend at 500 fpm and kept the trim pegged. At 5 miles
> out
> > I
> > > > slowed to get
> > > > set up for landing and noticed the pitch up trim wasn't working.
> > > > Fortunately I've
> > > > flown at night enough, so that that didn't add much to the problem.
> I
> > > had a
> > > > 5000 ft
> > > > runway and a direct 10kn headwind which was a good thing. Didn't
> know
> > > how
> > > > long my arm
> > > > would hold out so I took the fastest way in and kept my speed up to
> > 90kn.
> > > > Wasn't sure
> > > > if I could hold it off at 70. The landing was a little rough, but
> I've
> > > done
> > > > worse.
> > > > Today I checked it out and the trim is working fine. Can anyone tell
> > me
> > > > what
> > > > happened? I have fuses and no CBs so it wasn't that.
> > > >
> > > > John
> > > >
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>
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>
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>
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