REFLECTOR: Adjustable Canard

[Andrew Ellzey]

All this talk of having trim problems, I am seriously considering making my 
canard adjustable. I stated this about a week ago to see what kind of 
reaction it would get, but now I am truly going to pursue the possibilities 
of making it happen .Someone made the comment that this would be a dangerous 
option to consider and I disagree. With careful consideration to the pivot 
point hinges and placement of a single or double jack screws to distribute 
the load, and a good position indicator to know what your angle of attack 
was at all times, I believe you would have a valuable addition to an already 
sound design. I owned, restored and flew a 1964 M20E for 12 years with the 
standard Mooney adjustable tail, and always laughed when I looked at the 
elevator trim system on a Piper 180, (not a lot different to the current 
design of our Velocities) and thought of how much drag that huge trim tab 
must have produced. The tail of a Mooney pivots on two hinges with 5/16 
bolts for the hinge pins and the jack screw is only a 1/2 inch acme thread 
screw. Mooney also had a safety strap that would limit the distance that the 
tail could move if the jack screw were ever to break or strip. The whole 
trim system was manually operated with the trim wheel mounted on the floor 
next to the pilot seat. The trim indication system was built like a lawn 
mower throttle cable moving a pointer on a small indicator which was marked 
for take off and landing trim settings, nothing about the system needed any 
electrical power.    I know that it would take some additional work to 
design a seal system for the dog house, but again well worth the effort.

Andy Ellzey
XLRG

----- Original Message ----- 
From: "Ron Brown" <romott at adelphia.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Saturday, February 04, 2006 7:54 AM
Subject: REFLECTOR: Sparrow Strainer


> More trim "info" from something I saved from Mike Pollack a while back:
>
> "The sparrow strainer has negative lift by design.  As the airspeed 
> increases, the sparrow strainer tries to pull the aft side of the elevator 
> down causing the nose of the airplane to rise which slows the airspeed. It 
> works in relation with the fixed trim system to give a wider trim range 
> airspeed without retrimming manually.  It also seems to keep the canard 
> more stable in level flight. I have flown with and without one and prefer 
> the sparrow strainer."
>
> And to add fair and balanced coverage, here is what Steve Korney had to 
> say:
>
> "My sparrow strainer works as a trim tab...The faster I go, the more it
> pushes the elevator up, keeping the nose down...My sparrow strainer has a
> positive incidents of about 15 degrees...That is, the cord line angles up
> from the trailing edge to the leading edge...Are we all confused...???"
>
> Yep,
> Ronnie
>
>
> ----- Original Message ----- 
> From: "Pat Shea" <xl340hp at yahoo.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Wednesday, February 01, 2006 2:51 PM
> Subject: Re: REFLECTOR: Elevator Trim Spring
>
>
>> Steve,
>>
>> Actually, if the sparrow strainer is installed as the
>> factory prescribes, it makes the trim situation WORSE
>> at cruise. It has a negative angle of attack relative
>> to the elevator and is an upside down airfoil. Both of
>> this work to pull the trailing edge of the elevator
>> down at high cruise. Since the Trialing edge of the
>> elevator is above the in-trail position at high
>> cruise, the sparrow strainer is working against you
>> the faster you go. Of course all this would be very
>> undesirable without a pitch trim system - the good
>> news is we have one.
>>
>> The purpose of the sparrow strainer it to pre-load the
>> pitch trim spring more (by making it work harder) at
>> higher speeds. This helps stabilize the plane by
>> increasing the pilot force required to move the
>> elevator at these speeds. This increased pre-loading
>> also increases the amount of external force
>> (turbulence) requires to induce a pitch change.
>>
>> I know you changed you sparrow to be an aerodynamic
>> trim, but that is a completely different arrangement.
>>
>> Pat
>>
>> --- steve korney <s_korney at hotmail.com> wrote:
>>
>>>
>>> Guys.....
>>>
>>> The sparrow strainer takes care of the trim in
>>> cruise and top speed...  If
>>> it's set right...
>>>
>>>
>>> Best... Steve
>>
>>
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