REFLECTOR: Pitch Trim Mystery

Rene Dugas dugasd at bellsouth.net
Fri Feb 17 08:38:39 CST 2006 

Andy,
I was born lucky I guess.  My plane does "cycle" slightly and my S-Tec
30 does chase the altitude in fast cruise in even mild turbulence but a
bump on the stick at the right point nulls out the oscillations.  At any
speed less than 155 kts the autopilot works fine. I do use the strainer
and flew without it initially.  It dampens out the adjustment needed by
about 75%.  I did nothing special.  I used the incident devices with the
kit therefore I can not tell you exactly what the incidence is but it
works fine.  Any one interested will be able to see it in Texas at the
fly in.  I do have a heavy panel (approx 60 #'s fiberglass with aluminum
molded and bonded to back side Pics available for interested.) and no
ballast.
I wish I could be more help.
Rene' 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Andrew Ellzey
Sent: Thursday, February 16, 2006 6:47 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Pitch Trim Mystery

Rene,

You seem to be the only person that is saying that you aren't having
trim 
problems. Do you have any secrets that you would like to tell everyone
as to 
how you rigged your canard?

Andy

----- Original Message ----- 
From: "Rene Dugas" <dugasd at bellsouth.net>
To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
Sent: Thursday, February 16, 2006 5:56 PM
Subject: RE: REFLECTOR: Pitch Trim Mystery


> John,
> Two inches up seems awfully high from what I have heard over the past
6
> years of reflector monitoring.  My XL RG at 174 economy cruise
trailing
> edge is up 1/8th inch.  Stall is about 65 knots  No VG's.   At 190
knots
> TE is up maybe 1/4th inch.  At 210 knots in a slight dive it is not up
> even 1/2 inch.  I take off pilot only with TE down 1" with 100 #'s
over
> gross 2800 pounds it is down 2 to 2.5 inches(just reference numbers.
> Rene'
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
On
> Behalf Of John Dibble
> Sent: Thursday, February 16, 2006 3:56 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Pitch Trim Mystery
>
> 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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