REFLECTOR: Elevator Trim Spring

Randy Wharton rwharton at buckeye-express.com
Mon Jan 30 18:52:22 CST 2006


I concur on the Starship. I have a photo of the canard pivots on a Starship,
and I can only see where they could vary the sweep, not the incidence. A
quote from the Starship brochure: "The use of a variable sweep forward wing
allows for extension or retraction of flaps without having trim changes."

Randy W.

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Alex Balic
Sent: Monday, January 30, 2006 7:32 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Elevator Trim Spring

I was under the impression that the starship used variable sweep on the
canard, not variable incidence- this increased the lift authority at slow
speed (extended)  and reduced drag at high speed (swept) I agree that there
is a fundamental design feature to keep the canard stalling before the main
wing, but the particular aircraft that we are discussing might need an
adjustment of canard incidence to correct the pitch authority problem
without going so far as to allow the wing to stall before the canard-
really, a close and precise gauge of the incidences relative to each other
will determine if adjustment is needed.. 

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Hiroo Umeno
Sent: Monday, January 30, 2006 3:19 PM
To: Velocity Aircraft Owners and Builders list
Subject: RE: REFLECTOR: Elevator Trim Spring

I am not an aerodynamics specialist either but...

As I understand it, the relationship between the canard and the wing is
probably the most "sacred" among all the design element of the Velocity
(and other canard type) design.  It is supposed to be carefully tuned so
that the canard will always stall before the main wing does.  Breaking
that paradigm means that the main wing can enter stall before the canard
does and will deep stall the whole aircraft without possibility of
recovery.

That seems very scary to me.

Having said that, there have been an example of canard aircraft with
variable incidence of canard (Starship, etc).  So perhaps with careful
design study and flight trials, this may be possible.

Hiroo

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Andy Millin
Sent: Monday, January 30, 2006 12:52 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: RE: REFLECTOR: Elevator Trim Spring

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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>>>>
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>>
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>>
>>
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