Message-ID: <19981219055138.13181.qmail@www04.netaddress.usa.net>
Date: Sat, 19 Dec 1998 05:51:37
From: Dan Schaefer <dfschaefer@usa.net>
To: lancair.list@olsusa.com
Subject: control surface balancing
Mime-Version: 1.0

          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> 
>>
In reference to Dan Olsen's post about how he used a lead shot and 
epoxy slurry to balance his elevators.

Dan, it's easy to see you're an astute builder! I used almost the 
exact same method to balance my flight controls, with one slight little 
variation that builders coming up on that step might find some benefit.

I did about the same thing to determine the approximate weight needed 
to provide the correct balance except that I added a slight (1 or 2%) 
excess so that in effect, I started a bit over-balanced. When everything 
was added to the elevators, including paint, I then (as you pointed out) 
drilled out the excess a little at a time until I got exactly what I 
wanted. The only difference between your method and mine is I figured it 
was somewhat easier to remove the excess than add more if it was light.

I used this technique for the rudder balance weight as well though this 
needn't be as accurate (in my opinion) as the elevators.

The nice thing about using lead shot is the fact that if you buy a number 
of bags early on in the construction, they make terrific conformal weights 
that are invaluable during some bonding procedures. Then, when you no 
longer need the weights for construction, you use the contents for 
the balance weight. I'm not sure now but I think that about #7 shot is 
what I bought. I'm sure a mathematician could figure out the optimum shot 
size to use that would provide the most weight for the minimum epoxy 
but it's not me. And #7 seemed reasonable.

If only we could come up eith an affordable source of depleted Uranium 
we sould provide the necessary balance moments with significantly less 
total weight - but I guess that's not in the cards. Too bad - it should 
be possible to save at least 10 - 15 pounds per airplane. And "depleted" 
means that you or your airplane wouldn't glow in the dark or force you to 
wear lead-lined Jockey shorts (Excuse me ladies, don't know what your 
equivalent is).

Keep the dirty side down (and then wash it!)

Dan Schaefer
N235SP


____________________________________________________________________
Get free e-mail and a permanent address at http://www.netaddress.com/?N=1