jhearnsberger
Active Member
I attached the elevator pushrod tonight and the counterbalance arm on the left elevator is 1/32" - 2/32" higher than the HS at trail position. Should I be concerned about this?
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Elevators Uneven?
- Thread starter jhearnsberger
- Start date
Elevator twist... ??
I saw a similar problem in an orphaned -7A that I acquired. Suspect that the factory bend in the elevator skin was just slightly off. Or maybe Builder One biased the fold in the process of closing the skin. With the elevators attached to the HS and aligned flush at the counterweights, the inboard trailing edge of one elevator was about 20 mm lower than the other. This was visually quite noticeable in the shop. I suspect that it would have flown okay. After much consultation, laserplaning, and noodling, we drilled out all the perimeter (spar) rivets on the bottom side of one of the elevators including the spar and leading edge roll wrap, slid the skin on that side just a skooch to the right wrt/ the elevator spar, clamped it at the spar, and checked with the laser plane again and again. Eventually drilled all the open -3 holes up to -4, countersunk, and riveted with -4 rivets. Came out surpisingly true. Wasn't as much work as it sounds like. Added a few new rivet holes in strategic locations, some of the rivets were pulled rivets out of conveninece. Caught it before the tips were attached.
So, when you see a -7A with #4 rivets on the bottom surface of one elevator, that's me. But look how good the trailing edges line up! Extra work? Yes. I'd do it again.
- Roger Kellogg
I saw a similar problem in an orphaned -7A that I acquired. Suspect that the factory bend in the elevator skin was just slightly off. Or maybe Builder One biased the fold in the process of closing the skin. With the elevators attached to the HS and aligned flush at the counterweights, the inboard trailing edge of one elevator was about 20 mm lower than the other. This was visually quite noticeable in the shop. I suspect that it would have flown okay. After much consultation, laserplaning, and noodling, we drilled out all the perimeter (spar) rivets on the bottom side of one of the elevators including the spar and leading edge roll wrap, slid the skin on that side just a skooch to the right wrt/ the elevator spar, clamped it at the spar, and checked with the laser plane again and again. Eventually drilled all the open -3 holes up to -4, countersunk, and riveted with -4 rivets. Came out surpisingly true. Wasn't as much work as it sounds like. Added a few new rivet holes in strategic locations, some of the rivets were pulled rivets out of conveninece. Caught it before the tips were attached.
So, when you see a -7A with #4 rivets on the bottom surface of one elevator, that's me. But look how good the trailing edges line up! Extra work? Yes. I'd do it again.
- Roger Kellogg
Auburntsts
Well Known Member
Hmmm... and the elevators were in trail when you drilled the horns, right? Not sure how attaching the pushrod would cause one of the counterbalance arms to be higher than the other.
In any event I don't think it's an issue.
In any event I don't think it's an issue.
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Dave_Boxall
Well Known Member
Don't worry be happy.
No, don't worry.
Our 9A is like this...(maybe worse). We worried for several minutes, then walked around the hangar looking for a "Factory Aeroplane" with 2-piece elevators. After we'd found at a Robin where the elevators were over 3/4" different when in trail our 9A looked a whole lot better....
No, don't worry.
Our 9A is like this...(maybe worse). We worried for several minutes, then walked around the hangar looking for a "Factory Aeroplane" with 2-piece elevators. After we'd found at a Robin where the elevators were over 3/4" different when in trail our 9A looked a whole lot better....
Pat Stewart
Well Known Member
1/16 is about as good as you can get if not perfect. I have seen significantly worse.
Pat
Pat
