Another wingtip alignment question

[Fearless]

I've looked through the archives and have read where people have cut the aft end of the wingtips in order to get them to line up to the ailerons. Mine droop about 1/8 on one side and 1/4 on the other. Unfortunately I already riveted the ribs into my wingtips. If I cut the aft ends now do you think it will release enough with the ribs in place to make the alignment possible? Or will I need to remove the ribs? Of course one of the ribs is epoxyed and riveted into place. The tooling holes in the ribs are toward the bottom which I interpreted the plans to show so i believe the ribs are correct for the two sides. I did sand down the wingtip trailing edge to align to the aileron.

What have others done in this situation. I am building a 9A.

[carguy614]

The only way to really correct the alignment in both planes (perpendicular to the aileron and along the trailing edge) is to cut the tip with a hacksaw blade and realign with the trailing edge of the aileron. The installed tip ribs will be no issue. First, make absolutely sure that you have your ailerons and flaps in trail, using the gauge stick and the tooling holes in the outboard ribs. install the tips with the trailing edges cut. You may have to cut an upward slot in the outboard end of the tip to make it go. Clamp some stiff hardwood strips to the flaps and ailerons that extend past the cut wingtip. When you are sure you have them in trail, mix some epoxy and flox, and glue 'em up. Use wax paper or plastic wrap to insulate the tips from the alignment strips. After the cure, sand the insides of the tips to prep for reinforcement, mix some epoxy and flox, and pour it into the trailing edge. A strip or two of wetted cloth may be needed to reinforce the upward slit. This will bond it in for all eternity. A little file and paper work and some primer will smooth it all over.
All in all, the whole deal took me around 2 hours on my flying RV9A. I could not believe how small a misalignment of the tips could affect the way the airplane flew. I had 1/8 inch on the port side, and 1/4 inch on the starboard, and the long moment of the big 9 wings caused a VERY heavy wing. Yes, I had to repaint my wingtips after the procedure, but that was no real big deal either.
Hope this helps...Chris

[BillSchlatterer]

This may be obvious but it caught me unawares during the fitting process. I found out that if you don't lock the elevators in trail position when you fit the tips, you might get lucky or you might not,...

Because of the elevator push tube geometry, when you have full up elevator, it moves the aileron push tubes forward slightly at the sticks. Enough to pull them out of alignment by about 1/4 inch. If you fitted them with the elevators down, then you might be low or reversed if they were up.



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This is with the tooling holes lined up.



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Close up showing exact alighment



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But now tips and ailerons were absolutely flush,... until I go move the elevator to the full up position.

Not sure if this helps but it does make a difference and it can make it seem out of alignment when it's not. Just line up your ailerons and then go to the elevator and push it through while watching the ailerons. It's kind a surprising. You might not be nearly as far out as you think.

Hope this helps more than hurts :-)

Bill S
7a almost there

[nucleus]

Good timing for me.

I am gearing up to fix the uneven trailing edges on my wingtips. My plan is to do one at a time, clamping the aileron to the flap, and then rebuilding the wingtip to the aileron. This will give me even wingtip trailing edges, but they will not be aligned with the aileron in neutral trail, but a little below the aileron.

Anyone see a problem with this? I don't see another way to ensure exact symmetry.

Currently the right side wingtip is high and the left low, more than .5 inch difference, which created a heavy wing. Right now I have this tuned out with an aerodynamic aid on the bottom of the right aileron. Plane flies hands off with the ball centered except at speed. She wants a little left rudder at speed. This has changed in 140 hours of flight by the way. When I started she needed right pedal at lower speeds and no rudder at cruise.


Hans