SonexBuilders.net

Working on installing the leading edge of the left wing here. The skin came out of the box with an extra bend in it on the bottom that I did I did not see when doing inventory. With the help of somebody that knows how to do metal work we were able to get the extra 1’ bend out with his 10 foot bending break and some massaging of the skin. As I’m pilot drilling the skins to the ribs for the bottom I noticed there are some divets? in between the ribs on a few areas. I understand when you’ve bend metal and then bend it back it has been stretched and possibly this is why I have some divets/slumps in some of these areas. It’s only under side of the wing. This is not the typical indentations around the ribs. It’s in between the ribs. First question is one is this a aerodynamic issue in which case I really need to fix the problem and two what are some ways that I can get rid of these divets?

The top was done first and updrilled before I even started the bottom side nightmare.

Can't speak to the aerodynamics issue, but I can tell you where the original "puckers" came from.

The leading-edge skins are terribly under-bent leaving the factory. If you try to bring the back edges together at a single point, they will oil-can and leave you with said "puckers". Ask me how I know. I was never able to remove the dents to my satisfaction and ordered replacements. I used the already dented skin as a "tethered goat" and could repeat the oil-canning at will.

Vacuum-bagging the parts will make them less susceptible to the "pucker" and much easier to fit around the nose ribs. .

Well I did end up vacuum bending this one because I couldn’t get the holes to line up to the spar on the bottom side. Probably because of the added bend caused during shipping and because of the under bend that I am sure we can all agree with. After vacuum bending it, I didn’t even need straps to get clecos in the bottom holes! Just a push of the hand and things started lining up.

As for taking out the oil can flexing anyone have thoughts on how to “shrink” it to tighten things up? I saw somewhere that heating it and then applying ice could do the trick?

Also I may try removing all the clecos from the ribs to relax it and then put them back in to see if anything changes.

I did not vacuum bag mine. What I did was to focus on the top - get that nice and tight, both during drilling, clecoing, and finally riveting. If you cleco the top, then flip it and do the bottom, is it any better?

I did that exact process Bryan. Did the top first and the bottom second based on what I read here. My right wing turned out pretty nice doing just that.

Bryan Cotton wrote:I did not vacuum bag mine. What I did was to focus on the top - get that nice and tight, both during drilling, clecoing, and finally riveting. If you cleco the top, then flip it and do the bottom, is it any better?

Been a number of years ago but this is the method we used. There were boards and straps involved to pull everthing in place. The top was completed first and then the wing was flipped over & the bottom was finished.

Dale
3.0 Corvair/Tailwheel

I had a similar crease on one of the upper surfaces of the leading edge I only noticed after doing the vacuum forming so not sure if it was always there, or caused by the vacuuming. I spooned the crease out using the flat sonex spar bucking bar on the outside, and worked the metal from inside by rolling a table spoon and a rounded panel beaters bucking bar. The crease was totally unnoticable afterwards on a polished plane.

Yea the crease I can work out with the spoon I think. I am going to try the propane torch heat and then cold compressed air on the loose oil canny parts. Anyone have thoughts on that?

DWest wrote:Yea the crease I can work out with the spoon I think. I am going to try the propane torch heat and then cold compressed air on the loose oil canny parts. Anyone have thoughts on that?

A propane torch is hot enough to anneal 6061-T6. This is ok for fairings but I would not do it on structure. The skins are structure.

Bryan Cotton wrote:

DWest wrote:Yea the crease I can work out with the spoon I think. I am going to try the propane torch heat and then cold compressed air on the loose oil canny parts. Anyone have thoughts on that?

A propane torch is hot enough to anneal 6061-T6. This is ok for fairings but I would not do it on structure. The skins are structure.

Bryan's advice is good. Please dont heat it