Van's RV-9A in Aurora

The Big Picture

The Big Picture
Flying! 8/28/2011

Saturday, October 13, 2012

Right wingtip trailing edge

I finally conjured the nerve to break up a good airplane and split the right wingtip trailing edge.  With the trailing edge split and the rib removed, I could manipulate the structure as required to get it to line up nicely with the ailerons. 

Of course a prerequisite to this work was carefully adjusting the ailerons during the annual inspection using the jigs specified by Van's.  I measured and checked three times, so I'm confident this part is right.

After splitting the trailing edge, I mixed up some structural epoxy and flox and clamped the trailing edge in place, with a straight edge to make sure it all lines up properly.

After drying, I had a slight concavity, but the trailing edge is nicely lined up.  Next I match drilled the new rib and riveted in back in. Time to go test it out.

I'm typing this up about a month after doing the work, and I was very eager to make the test flight, and then very disappointed when it had absolutely no effect.  Double Drats!  I moped around for a couple of days, re-read the Van's heavy wing write up.  The last step of their analysis is, if all else fails, add a trim wedge.  So I  made up a styrofoam trim wedge to try out.

I used 3M brand speed tape (well OK, duct tape) and stuck the trim wedge to the bottom of the right aileron.  I had tried a trim wedge back in phase one, but it was not big enough.  This one apparently is - it completely solved the problem.  I tried a slightly smaller wedge, but went back to the first one.  Finally Cav flies hands off true, and the aileron trim is actually usefull for trimming out uneven loading.

Best of all, the trim wedge does not affect speed at all. I was afraid that a built in aileron deflection would add drag, but as near as I can tell, it stays pretty close to lined up with the trailing edge in flight, and didn't slow me down a bit.