Thorp Air Command - T18.net

As some/many are aware, I'm rebuilding damaged S18 wings. I thought I'd give a progress report.

The spar cap ding has been straightened. Well 99% to maybe 99.5% straight. Not sure I can do any better. And I decided to go with a "doubler" angle extrusion. Have to order the angle from aircraft spruce. I only need like 16".

The skins are off both outer panels. I'm now in process to remove as much of the pro-seal tank sealant off the main spars. I found that the thicker the sealant was, the easier it was to remove with a putty knife. It seems to keep it soft. Where the sealant is thinner, it is dry and harder/stiffer. I found brining it out into the sun to heat up some helped soften it.

I'm not sure how "clean" I need to get with the sealant removal. Does anyone know if it is OK to just reapply over the old sealant, or do I have to pre-treat it or have to get to bare metal to get solid adhesion?

I think I will be able to salvage the root rib on each outer panel. This will save a lot of work since the bell cranks and stiffeners are already in place. I am able to get at the edge flange of the rib to reasonably mark and match and transfer the existing holes in the ribs and onto the new wing skins I will have to order. Pretty much the rest of the ribs both nose and main ribs I think I will replace with new. Simply to make installing the new skins easier. Having only to match the locations of the rivets/dimples for the spar location.

Question: a few locations when I removed the rivets buggered up the hole a bit oversize. Other than looks, is there any problem with installing a 3/16" rivet in a few locations on the rib flange?

I know they sell an "oops" rivet for #40 rivets where you can insert a #30 shank with the small #40 head. Does anyone know if the make a 3/16 shank with a #30 head? That would be about perfect for those oversized holes.

I could try to post pictures, but they are not very entertaining.

B&B Aircraft Supply http://www.bandbaircraftsupplies.com list NAS1097AD 3, 4 ,5 & 6 oversized rivits, the only downside is they sell em in 1/4 pound lots at $3.75 each.

_________________
Bruce Finney
N18JF T-18C #262
Yelm, WA USA

What does "oversized " mean? Is that a full 1/16"?

With how much I will spend on this project, $3.75 is no big deal for a bag. I will buy the longest ones as I have a river cutter. I can make them shorter, but not longer!

Rivets are sized in 1/32" ie a number 2 rivet is !/32" in diameter a 3 is 3/32 . a 4 is 4/32. a 5 is 5/32 and so on
If you drill out a 4 rivet and clean it up you will need a 5 rivet

Ok so now I'm confused.

I understand that standard rivet sizes are in 1/32" increments. So what does oversized rivets mean as Bfinny mentions above?

What I would like is a #5 shank with a #4 head. Is that what over sized means?

I think Bruce used the wrong term to describe the rivet that has a 4 head with a 5 shank.
You are looking for NAS1097 rivets. These rivets have a small head when compared to a standard AN/AD rivet
Example a NAS1097AD5-8 will have a 4 head (small) with a .187 (5) shank and be 1/2" long