REFLECTOR: Sparrow strainer - I'm confused...

[Terrence Miles]

Geoff,

Over the past 10 years or so, the sparrow strainer debates  and opinions (which are always fascinating to me) and the “running out of trim” issue come up on a regular basis.  Geoff, you are hardly the first in the test flight phase to wrestle with this.  I have the RGXL-5 with a LY IO540.  I weigh 150 pounds.  Empty wgt she is 1928 lbs at 136.4   I know other light weight pilots like me that fly with ballast on the floor by the right seat.  I don’t because I have two nose mounted Odyssey batteries.  XC by myself with 70 gal of fuel and the usual crap in the back seat area (125+ lbs) I am at a CG of 130ish.  With a 185 lb copilot it goes to 128.3 or so if anybody out there is considering 2 nose batts be aware of that limit.   Because I am short I have the arm of my seat is 79 inches.  The copilot is at 83 inches.

 

I am not suggesting this for others, but with advice like you are seeking right now, and more than several conversations with Malcolm Collier and others, I decided to do this:  The factory trim spring didn’t fit due to insufficient space behind the panel without major changes.   Also the stock elevator trim motor throw was too short.  I have a speed brake trim motor running my elevator trim which is longer by an inch or two.  Yes, I have to watch for fractures in my sawed off, reduced curve spring, but  I don’t run out of trim no matter wgt, CG, or speed.  

 

Terry

 

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On Behalf Of Richard J. Gentil
Sent: Friday, September 14, 2012 10:31 PM
To: geoff.gerhardt at gmail.com; Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Sparrow strainer - I'm confused...

 

Geoff,

 

To help solve the issue I just cut my sparrow strainer in half. 

 

Richard 

Sent from my iPhone 4 Classic


On Sep 14, 2012, at 10:01 AM, Geoff Gerhardt <geoff.gerhardt at gmail.com> wrote:

Guys,

 

As I'm flying more, I'm getting a better feel for the plane and discovering little issues.  I noticed yesterday that when I really dangle (i.e. >160kts), I run out of down trim.  I guess I wasn't paying attention before, but as I speed up, I need to keep adding down trim - I thought that's what the sparrow strainer was for.  As speed increases, the canard is generating more lift, so the sparrow strainer trims the nose down so that less trimming is needed for speed changes.  But then, I was looking at the way the sparrow strainer is mounted and it looks like it would do just the opposite.  As speed increases, the sparrow strainer will be pushed down, adding trim up!  I have my aerodynamic trim installed as per factory instructions.  I've heard of some who install it upside down, which to me sounds like how it should be installed.  I have a feeling that if I remove it I'd have to trim less with speed changes.  Unfortunately, I used some pretty aggressive silicone glue to put it on and I'm afraid I'll make a mess of it taking it off.

 

Any thoughts on the effectiveness/correct installation of aerodynamic trim?

 

Here's now I have mine installed:

http://thegerhardts.com/velocity/?p=491

 

Geoff

 

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