Elev. Pull pull Question

[randy10926 at comcast.net]

I am redoing the setup on my excelleron90 also.
Randy

-------------- Original message -------------- 

Further reading and testing my Excelleron confirms your comments, Dean.  Thanks for the insights, as allways.  I have those DuBro things laying here...may just have to re-do the system.  Interesting how these seemingly-insignificant things add up.

Bob Pastorello
NSRCA 199  AMA 46373
rcaerobob at cox.net
www.rcaerobats.net


----- Original Message ----- 
From: Dean Pappas 
To: discussion at nsrca.org 
Sent: Monday, November 29, 2004 10:42 AM
Subject: RE: Elev. Pull pull Question


Hello Bob,
Go buy some DuBro # 867 control horns. They have almost 3/4" of overhang between the bolt and the little hole for the clevis, in the little screw-on pieces.
Use those pieces, but set the bolt and nut aside, and see if the little holes line up with the center of the hinges.
If not, then drill new holes in the black plastic bits so that they do line up: one straight line through both holes and the center of the hinge.
Now when you get the horns all the same length, it will be much easier to get the throws matched in both directions.
This is absolutely necessary for matching two elevator halves properly, but is also a good idea for rudders.
The problem with the stock setup is that the cables slacken at the ends, and tighten at neutral.
While this might sound like a good thing, it is awful: the servo has to fight the tightening cables as the surface comes closer to neutral,
then as it gets there, the surface may try to "spring" to the opposite direction.
The servo and gear train will prematurely beat themselves up chasing this problem.
You want the cable tension to be almost constant throughout the throw.
There will be pictures of this when I get the Excelleron review out the door.
One of the previous posts pointed to a website that showed the proper geometry.
DuBro and Rocket City both make parts that are useful, for this problem.

Check DuBro.com and put #867 into their search engine, you can see the lonng overhang part. It's either 5/8" or 3/4" from bolt to clevis hole.

Later,

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 
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