REFLECTOR: Sparrow Strainer

[Ron Brown]

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
>
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam?  Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
> _______________________________________________
> To change your email address, visit 
> http://www.tvbf.org/mailman/listinfo/reflector
>
> Visit the gallery!  www.tvbf.org/gallery
> user:pw = tvbf:jamaicangoose
> Check new archives: www.tvbf.org/pipermail
> Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>