REFLECTOR: Pitch Trim Mystery

Andrew Ellzey ajlz72756 at yahoo.com
Fri Feb 17 10:47:32 CST 2006


Rene,

Thanks for your response, I am waiting on warmer weather to continue with my 
wings and canard even though my shop is heated and insulated. I just don't 
want to take a chance on such large lay ups not fully curing in less than 
ideal temperatures. It is good to hear that you didn't have to deviate from 
the plans on your canard incidence. It is worrisome to hear when builders 
talk of having trim problems. It is also good to know that your elevator 
deviation is very small in fast cruise.This confirms that your canard 
incidence is at its optimum angle of attack for your aircraft's CG. Does 
your trim remain effective at all weight and CG configurations? I am 
interested in seeing your panel photo's, I haven't fully decided on my panel 
layout yet. With my line of work I can't plan as far ahead as the Texas fly 
in. I am going to try to attend even if I have to drive or fly commercial. 
If someone would like to pick me up on the way, I would be glad to 
contribute on fuel. I live three miles from ROG (5,500 ft runway) airport in 
Northwest Arkansas. There are several other Velocity owners close to my 
area, but I'm not sure whether they watch the reflector or not and plan to 
attend.

Andy


----- Original Message ----- 
From: "Rene Dugas" <dugasd at bellsouth.net>
To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>
Sent: Friday, February 17, 2006 8:38 AM
Subject: RE: REFLECTOR: Pitch Trim Mystery


> 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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>
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