[NSRCA-discussion] Trim changes

[Jim Woodward]

Hi Brian - ditto on "major' trim changes from morning to night on my two planes with the DEPs system.  However, my RCME Aggressor has two FUT9650's in the tail has almost no trim changes.  I plan to convert my other planes to a DESS (dual elevator servo system, :-) ) when I can get to it.  Not that the other two planes don't fly well, but the Aggressor (I have 3) with the dual elevator servos also tracks EXTREMELY well through maneuvers.  Now running YS, the other plane needed some tail weight anyway so as far as CG goes, I'll be fine to pop in the two servos and take out the lead weight/pushrods.

 

I think the real key to being happy with a two elevator system is to use this "Y" with "reverser & pot" from EMS.  http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXAFN1&P=ML  I first tried to match throws using two different receiver channels, matching servo centers and control geometry as best as possible.  Over two nights I absolutely COULD NOT get the throws to match to my satisfaction.  I then installed the servo reverser and used the little pot to adjust the center of the reversed servo.  Immediately, you could tell that the elevator ½s were moving perfectly in unison.  I also put pointers on it and it revealed that they were moving in unison up and down the full range.  

 

This little thing is worth the money, eases programming, and can be set/matched centers very quickly, saves a bunch of time too.

 

See you at the Tangerine.

Jim

 

________________________________

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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