-3B leading edge + tank skins jigging....

Hi,

...to those who were lucky enough to deal with the "slowbuilt" RV-3B wing kit : just before drilling into place both main top and bottom skins, do you simply jig&drill those main skins as per plans and then assume the somewhat pre-bent leading edge and tank skins are the good size and will fit and match perfectly around the L.E. ribs ?....

Knowing the -3 plans and kits, I just cannot figure out how to get this perfect fit on the "first try"........and if the L.E. and tank skins need some dimension and/or chordwise position adjustments (and they probably will need some....?!...) to perfectly wrap around the ribs ; sure it would be better to adjust main skins position - forward or aft - rather than re-cutting the L.E skins.....

...???....

Thanks for your help !

Hi Ian,
My recollection from building -3B wings is that you need to
verify that everything will fit before drilling. Don't assume
that the aluminum sheets you received from Van's match the
drawings or each other. Having said that, everything
in my wing kit was large enough to fit with some trimming.

Before mounting the main skins, draw lines on your spar
flanges where the main skins meet the leading edge and
tank skins. The position of these lines are important to
get appropriate edge distances for the rivets and tank
screws.

I went ahead and drilled the main skins to the spars and
ribs before fitting the LE and tank skins. This makes the
assembly rigid enough to remain straight when you use
strap clamps to pull the LE and tank skins down into position.

With this method you will probably need to trim the tank and
LE skins to fit. This is par for the course on the RV-3B; every
skin requires some trimming along at least 3 of the 4 edges.

One trick I used is to start drilling the tank and LE skins along
the top spar flange, and work your way forward to the leading
edge and then back along the bottom surface. Leave the
lower aft edge of the skins untrimmed (overlapping the bottom
main skins) until everything is drilled. With some care and effort
you can achieve a very close fit at these skin joints.

Good luck!

- Dan Benua
EAA Tech Counselor
Repeat Offender

Hi Dan,

OK....that makes sense !...

....assuming everything in the kit is large enough to fit with some trimming...(!...)...it seems reasonable to first drill the main skins as per plan design so as to get the assembly rigid enough, and then only to make to leading edge and tank skins match by trimming on edge....at the very least...

I was really perplex getting the real NACA L.E shape when butting those L.E and tank skins against the main skins with no trimming at all....I am not trusting that much the non-CNC RV-3 Kit !!....

Thanks for that piece of advice !....

Cheers !

Yann