RV7-tipup frame weldment misfit to skin issue?

Slagergren · #1 01-25-2009, 04:50 PM

Has anyone had good results in dealing with the large gaps between the 702 skin and the aft corners of the WD-716 frame? The gaps at the corners along the 3/8 OD tube are roughly 1/8" or greater from the skin.

I looking at a few possible options:
#1. Fill the holes in the skin with the largest gaps with rivets and skip trying to tie these holes to the frame. A few of the holes I could see adding some shims.

#2. Bend the corners of the WD-716 weldment to match the skin. The areas to be bent are located near where the tube connects to the side plates/ rails. Bending these to fit will require some custom form blocks to ensure the tubing is not damaged in the process.

Any thoughts are appeciated,
Steve

Brantel · #2 01-25-2009, 06:01 PM

Most if not all have this problem.

Some use longer blind rivets and put washers between there.

Others just pop the rivets outside of the tube and let the shop head sit on top of the tube.

A few have even custom fit a tappered shim to fit in there.

Even heard of some filling the gap with sealant like Sikaflex or Proseal.

There are tons of threads on the issue in the archives.

If you bend the frame, it will move somewhere else and that may cause a bigger problem later.

Greg Arehart · #3 01-25-2009, 06:05 PM

I just pin in shims, some as thick as 3/16" I center-drilled a piece of 3/8" diameter Al rod and then cut the shims to the necessary thickness (they look like thick Al washers). I have about 4 shims of different thickness on each side.

greg

Rupester · #4 01-25-2009, 06:46 PM

It seems the majority of the 7/9 Tip-ups have that issue. I will be using washers to fill the gap. (On mine it affects two rivets on each side fastening to the rear frame tube, just up from the side panel a bit.

dhall_polo · #5 01-25-2009, 07:41 PM

One of these days, Van's will come up with an improved canopy kit, and it will be our chance to share the "remember when?" stories with the newbies.

My solution was just to add a few non countersunk pop rivets in between the others in that area. This pulled the skin a little closer to the frame and added some strength.

Slagergren · #6 01-25-2009, 08:02 PM

Thanks guys, that was fast on the response. Well I started making skims (I like the idea of using aluminum round stock) and I "gently" massaged some of the frame areas using some "custom" contour wood blocks and clamps.

I can see that trying to bend and pull out all the little gaps could be risky not mention extremely time consuming.

Thanks again,
Steve

Pmerems · #7 01-25-2009, 08:55 PM

I too had this gap and wondered why. Then I had a chance to look at the canopy frame on the RV-7A prototype. It turns out that the tube on the prototype is welded a bit further outboard then the kit frames. So the factory doesn't have an issue. Or at least they don't think they do.

Additionally the prototype had flush blind rivets attaching the skin to the tube. They dimpled the skin and didn't dimple the tube.

Shim away like the rest of us.

Paul