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Aileron balance

From a Sage: "If it ain't broke, ........... (maybe) don't fix it"

How does it fly now? What problem are you solving?
 
Flys fine ....and has for 618 hours and I get the concept but worry about weight behind hinge line and potential for flutter .


I agree with your concern, the control surface CG should be on or ahead of the hinge. You could always just attach a weight to the aileron nose rib. If you can get something in the tube and secure that would be more forward. What about bonding in a steel rod?
 
Counterbalancing Aileron

I built in an aileron trim tab driven by a MAC servo on my RV4 back in the early 90's. What I did to offset the condition you describe was to place the servo as far forward, into the nose section, as I could. The particulars don't matter - but that is what I did. That alone, however, was not enough - I ended up with a condition like yours, but (probably) not as severe.

I re-balanced the aileron (off the airplane) using led shot from shot shell reloading; and, then mixed that amount with 3M 2216 epoxy adhesive, thickened with a bit of glass beads, and then located all of that into the bore of the leading edge counterbalance steel pipe.

Did the same thing on the Rocket in the late 90's - never had a problem with either one.

YMMV

HFS
 
you could probably even pour molten lead into the pipe. It would probably cool fast enough not to damage anything, just do a little at a time. The shot and epoxy sounds like a great idea.
 
Worth mentioning is that I used lead shot and West Systems epoxy for a marine project once. The lead would sometimes escape and the whole thing was a bit brittle. I regarded the part as marginally acceptable, even though it was wholly contained.

2216 is probably a better choice.

Even with that, take pains to clean the shot.

Dave
 
Guys,

They did a lot of experimentation on this point at NACA Langley.

Try TR-496 and its extension to trim tabs in ailerons TR-736 and TR-685

Specific to location of balance point, Try NACA TN-609.

IIRC, it doesn't agree with balance point ahead of the hinge line.

FWIW
 
Going from memory, I think Vans makes the point that it is just important to not have the CG aft of the hinge, since the ailerons are connected and aerodynamically balanced.

On the slip-fit tube idea, the blind rivets on the LE of the aileron will get in the way.

For the epoxy, mix in a little flox, that should solve most of the brittleness issues.
 
Many thanks to all ! So I think if I read that correctly is to statically " balance the aileron " much like you would an elevator? Makes good sense Cheers. Stew

The ailerons design on the two seat RV's, if built per plans, does not result in an aileron that is 100% statically balanced. There is a lot of service history that indicates that that is not a problem. Even with the wide variation in balance caused by the different paint finishes that have been applied over the years.

Even with that being true, my recommendation would be to add balance weight to an aileron that has been modified from the standard plans configuration, to bring it back to an equivalent level of balance that an unmodified one has (I.E., make it the same as the one on the opposite wing).

The best way to do this would be to add the weight inside the balance pipe. That is the farthest fwd location possible, so it will allow for adding the least amount of additional weight possible.
If it were me, I would use a runny flox mixture with small sized shot. This should reliably stay together. Once added to the pipe, the pipe could be plugged and the aileron stood on end so that the mixture migrates to fill the entire I.D. of the pipe.
 
I personally wouldn't be concerned with adding the weight along the entire span. You will be adding a small percentage of the overall amount. Assuring that it stays put is much more important than distributing it evenly. That is why I suggested standing it on end while it cured.
 
I personally wouldn't be concerned with adding the weight along the entire span. You will be adding a small percentage of the overall amount. Assuring that it stays put is much more important than distributing it evenly. That is why I suggested standing it on end while it cured.


Put the weight opposite the trim..........
 
The epoxy/lead shot idea sounds like a good one, but if you proceed with the sleeve inside the existing balance pipe solution, there might be a simpler way than machining grooves to clear the existing pop rivets.

You can't possibly need more than a few ounces, so likely a thin walled tube is all you'd need. If you use one that matches the ID of the existing pipe, Why couldn't you just cut it to a length that gives you the additional weight you're shooting for, drill out a few of the existing pop rivets, slide your new sleeve in to the location you want the weight, match drill the new sleeve through the holes, then wet install it with a thin coat of epoxy and install new longer pop rivets through the whole thing?

Then stand back, say "that's not going anywhere" and forget about it.
 
Water pipe

Great thanks .... someone had mentioned that it was galvanized water pipe but I actually thought it was a " tongue in cheek " comment. That makes things super easy then. Just need some longer rivets and I am fully supplied I think to start .... Many thanks for all the help and excellent suggestions. Cheers. Stew
 
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