REFLECTOR: Elevator Trim Spring

John Dibble aminetech at bluefrog.com
Mon Jan 30 15:15:41 CST 2006 

I you reduced the angle of attack that would give better efficiency at high speed, but
you would  lose the stall correcting feature of the canard and run the risk of a deep
stall.

John

Andy Millin wrote:

> I suppose you could if you wanted to experiment.
>
> I'm not an aerodynamic engineer.  Just some thoughts.
>
> It would make it difficult to seal the doghouse.  Would be cold and windy.
>
> Would need to find a way to attach and balance the whole canard.  Attach
> points would probably need to go right about where the middle of the spar
> cap is now.  But, you could find a new attach if you wanted to work at it.
>
> Would be quite a bit of mass to move around with the controls.
>
> The canard provides a significant amount of the lift.  Small changes in
> incidence would probably translate into large changes in pitch.  Would want
> to have plenty of mechanical advantage to keep it from slamming to the
> stops.
>
> If you screw it up, you'll probably only get one chance at it.
>
> Not my cup of tea.
>
> Andy
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
> Behalf Of Andrew Ellzey
> Sent: Monday, January 30, 2006 2:55 PM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: Elevator Trim Spring
>
> Just a thought for everyone, not that we need to reinvent the wheel. Why
> couldn't the angle of attack of the canard be made adjustable for trim, just
>
> like Mooney's tails are made to pivot for pitch trim. There isn't any
> additional drag induced at any trim settings with the Mooney's tail
> configuration.
>
> Andy
>
> ----- Original Message -----
> From: "Scott Derrick" <scott at tnstaafl.net>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Monday, January 30, 2006 1:02 PM
> Subject: Re: REFLECTOR: Elevator Trim Spring
>
> > John,
> >
> > I wasn't suggesting you use a shim block, you get to do whatever you
> > want
> > to. though I got the idea from a factory A&P.
> >
> > I was asking Ron why he chose to move the actuator when adding a shim
> > block seems much simpler and accomplishes the same thing in my mind.
> > Maybe I'm missing some aspect that moving the actuator accomplishes?
> >
> > Scott
> >
> > John Dibble wrote:
> >> Ronnie,
> >>
> >> I'm sorry, but I'm getting more confused.  My problem is that I don't
> >> have enough down
> >> (elevator up) trim at cruise.  I can see how moving the actuator forward
> >> could help
> >> this problem.  I don't understand why I need to cut the bracket.  Can't I
>
> >> simply move
> >> it forward and make new holes in the canard?  I didn't build so maybe
> >> that is why I
> >> don't understand.
> >>
> >> Scott D - I think your idea of the block is going to send me in the
> >> wrong
> >> direction.
> >> Appreciate your help here.
> >>
> >> John
> >>
> >> Ron Brown wrote:
> >>
> >>
> >>> Morning John,
> >>>
> >>> No, lets try again.
> >>>
> >>> The objective is to move the actuator forward a bit which provides
> >>> more
> >>> up
> >>> (elevator down) trim.  (That is if you have a problem with not enough
> >>> "up"
> >>> trim when in cruise configuration, only one person in front seats.  This
> >>> solution allowed me to not only cruise without pushing forward on the
> >>> stick,
> >>> but also to trim for a 500 fpm descent with a slight reduction in
> >>> power).
> >>>
> >>> To move the actuator forward, you will need to cut the canard attach
> >>> bracket
> >>> so that the hole is gone.  Now drill a new hole that is 1/4" to 3/8"
> >>> forward
> >>> of where the old hole was.
> >>>
> >>> By the way, the bracket shown in the new on-line manual is different
> >>> from my
> >>> 1999 kit.  The new bracket (Long Bracket VAB-02) shown on page 10-8 of
> >>> the
> >>> online manuals is shorter than mine.  What ever bracket you have, the
> >>> objective is to move the forward part of the actuator about 3/8" toward
> >>> the
> >>> nose of the plane.
> >>>
> >>> Ronnie Brown
> >>>
> >>> ----- Original Message -----
> >>> From: <aminetech at bluefrog.com>
> >>> To: <reflector at tvbf.org>
> >>> Sent: Sunday, January 29, 2006 10:03 PM
> >>> Subject: Re: REFLECTOR: Elevator Trim Spring
> >>>
> >>>
> >>>> Ok.  Let's see if I got this.  You're talking about the bracket
> >>>> that attached the actuator to the canard?  And you shortened the
> >>>> bracket so you could move it aft? And then
> >>>> you drilled a new hole in to bracket and attached to the old aft hole
> >>>> in
> >>>> the canard?
> >>>> Did you drill a new forward hole in the canard for the other bolt?  How
>
> >>>> am
> >>>> I doing?
> >>>>
> >>>> John
> >>>>
> >>>> Ron Brown wrote:
> >>>>
> >>>>  John,
> >>>>
> >>>>  I had the same problem with my 173.
> >>>>
> >>>>  I cut the trim actuator front mounting bracket off at the front of
> >>>> the old  bolt hole.
> >>>>
> >>>>  Then I drilled a new hole about 1/4" or 3/8" ahead of the old
> >>>> hole. Problem  fixed, and I still have plenty of up trim for take
> >>>> off.  Easy fix.
> >>>>
> >>>>  Ronnie
> >>>>
> >>>>  ----- Original Message -----
> >>>>  From: "John Dibble" <aminetech at bluefrog.com>
> >>>>  To: "Velocity Aircraft Owners and Builders list"
> >>>> <reflector at tvbf.org>
> >>>>  Sent: Sunday, January 29, 2006 3:11 PM
> >>>>  Subject: REFLECTOR: Elevator Trim Spring
> >>>>
> >>>>  > Flying solo, I run out of down trim at 155 IAS.  On the other
> >>>> hand I  > have plenty of up trim for TOL.  Can I make a wedge shim
> >>>> where the  > spring attaches to the elevator tube to shift the
> >>>> adjustment range to  > more down and less up, or do I simply have
> >>>> to add more glass to the  > spring to make it stiffer?
> >>>>  >
> >>>>  > John
> >>>>  >
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