[NSRCA-discussion] Trim changes

Fri Dec 8 06:39:10 AKST 2006

I have a home made DEPS system in my fiberglass fuse/wood crutch EMC and 
still see a good deal of elevator trim change as temperature changes.  I'm 
sure some of the trim change can be attributed to air density changes 
changing the AoA along with the expansion/contraction coefficients of the 
different materials.  I know a great deal of the change is in the 
expansion/contraction coefficients of the different materials as I also see 
my rudder cables loosen/tighten. The elevator trim change in itself isn't 
bad unless the aircraft requires a bit of rudder to elevator mixing, then it 
creates a problem.  So I'm leaning towards 2 elevator servos mounted in the 
stab on my next pattern plane.
Ed M.
----- Original Message ----- 
From: "Dean Pappas" <d.pappas at kodeos.com>
To: "NSRCA Mailing List" <nsrca-discussion at lists.nsrca.org>
Sent: Friday, December 08, 2006 10:07 AM
Subject: Re: [NSRCA-discussion] Trim changes

Hi Nat,
I'm using the Sullivann composite tube-in-tube pushrods in a wooden fuselage 
model right now. The expansion coefficients are far from mtched, though it 
is rather predictable. If it's colder than last time I flew, I will need up 
trim and vice versa. The trim change is a factor of 2 or 3 worse than if I 
had a fiberglass/carbon pushrod in the plane, but tons better than an old 
Nyrod, and tons cheaper than carbon fiber rods. My serious airplanes still 
get carbon rod DEPs.
Dean.

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org 
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Ed Alt
Sent: Friday, December 08, 2006 1:12 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Trim changes

Nat:

It starts on this page: 
http://www.rcuniverse.com/forum/m_3637235/mpage_4/key_prestige/tm.htm 
<http://www.rcuniverse.com/forum/m_3637235/mpage_4/key_prestige/tmhtm>

Yes, it's the Sullivan composite version for the inner pushrod.  Actually, 
the Prestige is nearly all wood.  It's a balsa composite shell with thin FG 
layer on the inside, pressed into balsa and then coated with whatever they 
create the finish with.

Ed

----- Original Message ----- 
From: Nat Penton <mailto:natpenton at centurytel.net>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Thursday, December 07, 2006 9:36 PM
Subject: Re: [NSRCA-discussion] Trim changes

Ed
I'm having trouble finding the Prestige thread. Can you help me out ?? Are 
you using the Sullivan composite inner pushrod ? Would they be of any 
benefit in a wood fuse ?                 Nat
----- Original Message ----- 
From: Ed  <mailto:ed_alt at hotmail.com> Alt
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, December 06, 2006 10:53 PM
Subject: Re: [NSRCA-discussion] Trim changes

You might want to check out the Prestige thread under Pattern on RCU.  I 
adopted a pushrod method that Dave Lockhart has used for some time and there 
are some pics and description there.  I think Dave's installation method is 
more highly evolved than what I patched together, but I think what's shown 
in the thread is a reasonable facsimili.  When you first hear about using 
Nyrods, you will most likely be very skeptical.  I sure was.  These are 
different though, since they have the CF slider vs. the usual junk.  There 
is some change with temperature, but not nearly as much as I have 
experienced with other methods.  It's really light, really cheap and not too 
difficult to install.  It's also a very positive control feel.

Ed
----- Original Message ----- 
From: Nat Penton <mailto:natpenton at centurytel.net>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Wednesday, December 06, 2006 11:27 PM
Subject: Re: [NSRCA-discussion] Trim changes

Amir
All that fine weather is bad for relations !

I use Kevlar pull-pull on rudder, balsa fuse, and with high humidity I am 
worried the servo will be uprooted. Need to adjust atleast daily. Also use 
DEP on elev ( 20 years ) and have trim changes sometimes hourly. I need to 
change both.            Nat
----- Original Message ----- 
From: Amir Neshati <mailto:amirneshati at earthlink.net>
To: 'NSRCA Mailing  <mailto:nsrca-discussion at lists.nsrca.org> List'
Sent: Wednesday, December 06, 2006 2:21 PM
Subject: Re: [NSRCA-discussion] Trim changes

I thought it went like, "wood fuse, pull-pull, fiberglass fuse, pull-pull, 
carbon fuse, pull-pull." Lightest set up too.

65 degrees, sunny, calm, clear & comfortable....

Amir

  _____

From: nsrca-discussion-bounces at lists.nsrca.org 
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Dean Pappas
Sent: Wednesday, December 06, 2006 11:25 AM
To: NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Trim changes

Hi All,
Back in the Stone Age (Ron remembers this) we always said, "wood fuse, wood 
pushrod and fiberglass fuse, fiberglass pushrod.
As long as the elevator trim is the only one that changes, then life is 
simple especially with crossed digital trims.
Putting the servos in the tail works, as does an MS-10 or Matchbox.
So does putting a 1:1 bellcrank halfway between the servo arm and the 
elevator horn. That's a trick that nobody uses anymore.

Dean

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com
-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org 
[mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Jay Marshall
Sent: Wednesday, December 06, 2006 2:06 PM
To: 'NSRCA Mailing List'
Subject: Re: [NSRCA-discussion] Trim changes

Some servo electronics could be temp sensitive. Measure the elevator on a 
cold morning then warm it up slowly with a heat gun (carefully) and see if 
anything moves.

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org 
[mailto:nsrca-discussion-bounces at lists.nsrca.org] On Behalf Of Brian 
Billings
Sent: Wednesday, December 06, 2006 12:05 PM
To: nsrca-discussion at lists.nsrca.org
Subject: [NSRCA-discussion] Trim changes

I have been dealing with elevator trim changes on my D.E.P.S. installation 
which has been worse with cold mornings and warm afternoons. Last night on 
the way home from the field I got the idea of figuring out a way to take the 
pot out of the servo and mounting it on the control surface, that way the 
surface will always go to it's set position regardless of how much the fuse 
has expanded or contracted. Anybody ever try this, I know it could be done 
but is it practical? My worry is vibration, sealing the pot from the 
elements, oil, keeping a clean signal with the long leads to the rear and a 
positive connection from pot to surface. Is this a dumb Idea?

Brian

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