REFLECTOR: Not enough Trim authority

Terry Miles terrence_miles at hotmail.com
Tue Nov 17 09:59:25 CST 2009


Dear all,

I'd like to toss in my two cents and experience to date, but we are probably
best helping each other by stating after our name what model we fly, what
engine/prop combo.  It makes a difference for builders.  I remember my own
building time and being confused by some posts that didn't apply to my bird.


I have my sparrow strainer installed per the book.  I have two batts in the
nose for w&b issues done during the construction because of guys in XL's
with the LY540 engine spoke of needing nose ballast.  I weigh 155 lbs my
wife is 125 lbs or so.  Were we bigger, I would advise against permanent
balast like an extra battery and use lead shot as needed on a flight by
flight basis.  

In 200 KTAS cruise at 8500 feet I trim to very slightly elevator trailing
edge up.  (Maybe 1/8 inch).  I stall at 68 kts.  I fly final in the low 90
knot range, and do not run out of trim.  I use a stock (old style trim
spring, that I shortened in overall length, and the narrowed in overall
width by flight testing so as to: 1)Have reasonable trim spring resistance
and 2)Have it fit behind the panel. These are separate issues.  Here is a
3rd:  I also have a longer throw trim motor.  The kind you get with the
speed brake.  I swapped w/ my speed brake motor due space in that area w/
the -5 drop down keel and being a RG.  All this under the tutelage of
Malcolm Collier and Hangar 18.  

Terry
Xl-RG-5
LY IO540 300 hp
Aerocomposite prop

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of aminetech at bluefrog.com
Sent: Monday, November 16, 2009 21:31
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Not enough Trim authority

Scott,

The other thing to consider is canard incidence.  When I fly solo, which
puts me very close to the aft cg limit, the canard stalls at 60 kn.  A
higher stall speed would indicate the incidence is high and that would add
to the trim problem at cruise.

John

--- scott at tnstaafl.net wrote:

From: Scott Derrick <scott at tnstaafl.net>
To: Velocity Aircraft Owners and Builders list <reflector at tvbf.org>
Subject: Re: REFLECTOR: Not enough Trim authority
Date: Mon, 16 Nov 2009 16:29:58 -0700

John,

Musta been somebody else.  I've flown sans strainer and standard
install. Its on now with the flat side up, which I believe is the
standard way?    That would apply more up force which is exactly my
problem! 

I'll take it off and try it.  Then install upside down and see how all
three methods come out.

thanks,

Scott


aminetech at bluefrog.com wrote:
> Scott,
>
> Before I reversed the sparrow strainer, my pitch trim ran out at 155-160
kias.  I recall that you tried reversing it and didn't have enough trim up
for approach.  Perhaps no strainer at all would be a happy medium that would
work for you.
>
> John
>
> --- scott at tnstaafl.net wrote:
>
>
>
> I do have a problem with the trim.  I just don't have enough down trim
> for cruise speeds.  If my indicated is 150kias or below its fine. I am
> using the Strong System because I was under the impression it had a
> wider range of trim than the factory design. Now I wonder.  I have
> plenty of up trim on approach with single pilot but I haven't loaded up
> the front yet(forward cg).  Still waiting for the new Catto prop before
> I add any more ballast to the front seat.  I have the system installed
> so its got about 60% down trim travel, and 40% up trim, so I'm already 
> over  compensated  for down trim.  The instructions call for 50/50.  
> I'm sending Alex an email to see what he recommends.
>
> In the mean time I'm thinking about plan B, which is to reinstall the
> factory trim, but stiffen up the spring somewhat to provide more trim
> authority.  I'msomewhat reluctant because of the problem of runway trim
> with a stronger spring.
>
> What are the fast V's doing?  I had marginal trim before with the
> factory spring, not quite enough down, just barely enough up with the
> io360.  Thats why I changed to the Strong system. 
>
> Anybody else have this problem?  Solutions?
>
> Scott
>
>
>
>  
>
>
>
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>   



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