Elevator balancing - adding weight

lostpilot28 · #1 10-22-2009, 05:53 PM

I've just got my airplane painted and was hoping my left elevator would be a little closer to balanced, but the addition of paint didn't have the effect I was hoping for. I have permanently installed the elevator tips and painted over them, so they're not coming off.

Any suggestions on how to add weight to the left elevator? The only solution I could find was pouring a lead-shot/epoxy mix into the tooling hole and tipping it forward until it cures. I could easily do this, but I'm not sure if that's the best approach. I'd hate for the glob of lead to come loose inside the tip.

RFazio · #2 10-23-2009, 07:12 AM

When we balanced our tail before paint we left a little extra weight forward. We figured that after painting we would drill a little weight off the lead to get a perfect balance. Guess what, we painted and now it needed more lead. What I did was to add another little square of lead behind the original one. I used two #8 rivnuts into the aluminum and screwed the lead on to the aluminum tail. I worked out ok. Though if you get the weight more forward, like your idea, it will require less weight. I was worried it would come loose and flop around in there. The total I added was 8 oz I think.

decathlon737 · #3 10-23-2009, 07:31 AM

Fasten a #10 platenut to the outside of the tooling hole with cs blind rivets. Your weight will hide the platenut.

lostpilot28 · #4 10-23-2009, 08:10 AM

Quote:

Originally Posted by decathlon737

Fasten a #10 platenut to the outside of the tooling hole with cs blind rivets. Your weight will hide the platenut.

Hi Bill, do you mean on the inboard side, because that's the only side I have access to? How would I attach lead to it? Sorry, I'm confused!

rvator51 · #5 10-23-2009, 08:32 AM

Quote:

Originally Posted by lostpilot28

Any suggestions on how to add weight to the left elevator? The only solution I could find was pouring a lead-shot/epoxy mix into the tooling hole and tipping it forward until it cures. I could easily do this, but I'm not sure if that's the best approach. I'd hate for the glob of lead to come loose inside the tip.

I have heard that many people use the above procedure. I wonder if you could spray some expanding foam into the tooling hole after the lead shot/epoxy mix cures to fill up the space as a safety measure just in case the lead shot/epoxy spray comes loose?

I put an extra platenut on my tips before closing them up just in case I had to add lead later.

N941WR · #6 10-23-2009, 09:00 AM

Quote:

Originally Posted by rvator51

... I wonder if you could spray some expanding foam into the tooling hole after the lead shot/epoxy mix cures to fill up the space as a safety measure just in case the lead shot/epoxy spray comes loose?
....

You don't want to use expanding foam any place where water can get in it. The foam will hold the water and corrode your aluminum.

I did use some expanding foam to hold my fuel lines in place and that has worked well because, as I said, no water gets to them.

pazmanyflyer · #7 10-23-2009, 09:48 AM

Here's what I did.

http://picasaweb.google.com/pazmanyflyer/01Empannage#

I borrowed the idea from some one else that I saw on an old RVhotline newsletter and I did it before attaching the tips but it's easy to do after painting also. Drilled out and added a nutplate to the existing tooling hole. I can comeback later and add a nut and washers to balance them if needed. These are located inboard of the elevator tips so access is easy.

David-aviator · #8 10-23-2009, 10:44 AM

Quote:

Originally Posted by lostpilot28

I've just got my airplane painted and was hoping my left elevator would be a little closer to balanced, but the addition of paint didn't have the effect I was hoping for. I have permanently installed the elevator tips and painted over them, so they're not coming off.

Any suggestions on how to add weight to the left elevator? The only solution I could find was pouring a lead-shot/epoxy mix into the tooling hole and tipping it forward until it cures. I could easily do this, but I'm not sure if that's the best approach. I'd hate for the glob of lead to come loose inside the tip.

Sonny,

Have you checked balance with the elevators connected together?

Van's does not have much to say about elevator balance except they should "remain in trail". (no limits are specified as to degrees up or down)

Since the elevators act as one unit when installed, not separately, to have them in trail as a unit you may find that by adding weight to the left counter weight, weight may have to be removed from the right side when they are connected and become one unit.

That's how I checked elevator balance on my machine. Granted, you do not want one way down and the other way up and end up balanced when connected, but if they are in the ball park separately they should be ok together. They should balance in trail as a unit.

I guess the proof of the pudding is in flight. During flight test the elevators did not flutter (fortunately-thankfully) even when doing the Vne check at altitude referencing IAS rather than TAS. I did not add or remove weight on either side and they have a lot of primer and paint on them.

lostpilot28 · #9 10-23-2009, 11:05 AM

Quote:

Originally Posted by pazmanyflyer

Here's what I did.

http://picasaweb.google.com/pazmanyflyer/01Empannage#

I borrowed the idea from some one else that I saw on an old RVhotline newsletter and I did it before attaching the tips but it's easy to do after painting also. Drilled out and added a nutplate to the existing tooling hole. I can comeback later and add a nut and washers to balance them if needed. These are located inboard of the elevator tips so access is easy.

Hi Carlos, I can't do that because my tips are already permanently attached (see the original post).

David, I want to balance each elevator independantly of the other. In the event that I ever exceed Vne for some reason, I'd like the added margin of flutter resistance by having each one balanced separately.

I'm just looking for ways to balance the left one by adding weight. I need ideas for the addition of weight...so far, it looks like the lead + epoxy method is my only choice. The expanding foam isn't a bad idea, either. I don't have to fill it up completely, just enough to assist in keeping the weight from shifting.

Any more ideas?

pazmanyflyer · #10 10-23-2009, 11:52 AM

Quote:

Originally Posted by lostpilot28

Hi Carlos, I can't do that because my tips are already permanently attached (see the original post).

So you've closed off both the outside (tips) and the inside (interior space between elev and HS) of the elevator? If you haven't done anything with the opposite interior side of the elevator then this still can be done. Maybe you can use a Rivnut instead of a platenut.