counterbalance weights

[fairchild1934]

i was thinking about making the tube counterwights that go in the aerolons--- by pouring a slurry of #8 shot and epoxy in an aluminum tube. Instead of melting the shot and pouring it in.
Which way is everyone doing it ?

Tim

[jaredyates]

You will find some differing experiences on this task in part because the diameter of the aluminum tube changed over the years. If you have a 1" tube, you will have no problems with the fit. If you have a 3/4" tube, you will need to put some testing and thought into ensuring your method gets enough weight in the tube.

[U2fletch]

We have the 1" tube in our BH5 and I repurposed a bag of #9 shot leftover from my days when I shot skeet. We covered in Oratex, so did not need to completely fill the tube. The first aileron I forgot to take into account the weight of the epoxy that I was adding. That extra few ounces was noticeable. I 3d printed some balance jigs that have bearings from my spare parts bin

Aileron Balance Jig.jpg

[fairchild1934]

my plans say "7/8" for the aerolon tube. Do you build the tube in when you assemble the structure and then leave a hole in the middle of the tube to pour in the shot ? Looks like you cant get the tube in or out after the building unless you leave a 1 inch round hole in the butt rib---
also---- how is the tube attached to the rest of the structure ? Do you fab some 90 degree brackets between the tube and the ribs ? Or a top hat shaped round thing ? (at 3 or 4 ribs)

[jaredyates]

My plans depict "S. S. Pop Rivets" which I always thought was a good name for a boat, but he means stainless steel pop rivets to hold the tube in place.

[Dpearson]

I did the melt and pour lead technique. It was fun but a bit nerve wracking. Wear PPE and ensure the tube is well supported and stable if you do it that way.
I used the same method for elevator counterbalances too.

[gregc]

There are a number of ways to do it. I didn't like the epoxy mess or the toxic lead fumes so I poured in #10 shot, tamped it down well and used aluminum plugs on each end. A pin or pull rivet through the plug and tube holds them in place.

[fairchild1934]

oK--- thanks--- I will take those ideas down to the basement where the plans are and see if I can understand that-----

[Ryan Koeneke]

I permanently installed the counterbalance tube with rivets before covering. Then I hung on the wing, poured lead shot in dry while the control surface was standing vertically, then plugged the end of the tube, hung it, took some weight out, hung it, took some weight out, until it balanced. Then I weighed the dry lead shot. Separately I mixed up some epoxy, weighed that and removed enough lead shot to off set the weight of the epoxy, mixed it up, and poured it in. Then made a plug out of epoxy and microbaloon paste. I was happy with how they balanced out.

[dramsey]

Bearhawk 5 kit here. I had read a Mark Goldberg comment somewhere to just fill the tube with lead shot. That sounded too simple but after paint I poured in the shot and temporarily taped over the end and hung the aileron. It was perfectly balanced. I then removed the aileron and sealed the lead with an epoxy slurry..

[Bearhawk Aircraft]

The tube is almost always filled full when balancing. It is sized to fit the estimated weight required to balance when using #8 shot. If your control is really heavy you may require smaller shot or tungsten, that is an extreme case. It will all depend on the covering and paint process used. Lighter the paint, the less balance needed. Each control should be balanced individually without control mechanisms hooked to it. Tail heavy controls will lead to very high aileron forces and fluter concerns.

[fairchild1934]

thanks to all---
Ryan --- your procedure sounds pretty nice... ! I might try that. if I assemble the aerolons now it will be some time before I cover them. Just dont want to paint myself into any corners.....
Tim