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Ski-Jump skins on finished wings.

I

instructor_bill

Well Known Member
talked with Scott at Van's yesterday about my top skin alignment at the flaps. I was certain somthing was incorrect but didn't know what I should do about it at this point.

It seems I have the "ski jump" alignment at the top skin to flap union and I have to use the "special tool" to rebend the rear spar. It seems that the -9 had quite a few that had misbent spars as well as a few -7's (that I can find reading here)


Has anybody used this special tool? What are your results?

I'm really sad:(

should I be?
 
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I tried with my palm and a section of hardwood and have read that thread-- and others

it seems that I can correct the position of the trailing edge of the skin, but really I'm only affecting the skin and not the spar.

I worked a section of the inboard skin about a foot long in this manner and found that while it was possible to get the skin to lay on the flap, I ended up with a lump at the rear spar starting with an indentation or concavity ahead of the rear spar and a convex section aft of the spar until it arcs to the skin .

I'm not certain, but I think that bending the rear spar will be a better fix as the skin will stay flat and will also remove the concavity forward of the spar. The ribs meet the forward edge of the spar totally flush and then the skin rises, that's what I'm trying to correct.


Has anybody used Van's special spar bending tool?
 
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Used Van's special tool with success

Bill,

I had the same issue on my RV7 wings. Made the tool out of 2x4 hardwood (Aussie mountain ash) and great success with the final outcome on the skin trailing edge. Make sure the cut in the tool allows for the rivet heads on the underside of the skin and take it a little at a time. I used a smooth ege to confirm when the skin was staight fwd/aft over the rear spar. If you attempt to just use your hand for this you will end up bending the skin around the spar and end with an unsightly 'bump'. Mine is now all flush from front to rear and aligns the wing top skin trailing edges from the flaps to the ailerons without any noticable blemishes.

Well worth the effort asthetically and no doubt will give an extra 0.0042 knots.:)

Cheers, Greg (RV-7A FADEC IOF-360)
 
I used Vans supplied tool

I used the fixture supplied by Vans and it worked flawlessly. It is way more robust and adjustable than anything I would have spent the time to make. I highly recommend obtaining it from Vans since it is free.
 
got to use the special tool

I'll agree now that I've used the tool.

I needed to both bend the rear spar until the skin was perfecly in trail with the natural line of the airfoil as well as gently pull the flap skin upwards so that the flap skin continuously rode the inside of the upper skin throughout its travel.

I'm fairly happy with the results other than some minor marks in the upper skin that I'll be able to block out with high build primer. They're minor, but they are dents that are visible at a very slight angle
 
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