Fitting HS Skins to Ribs

Okay, now that I'm started I seem to have a little problem getting the HS904 front ribs ( I think that's the correct part no.) into the skin. I cut the templates out of the plywood as directed, I even "took the mark" thinking that it needed to be a little wider for the foam to protect the skins. The middle front rib fits great, but the outside two are way too tight. I've fluted the nose significantly to shrink it, to no avail. I'm about to pull it out of the wooden fixture to see if that's the problem.
Any suggestions will be appreciated.
Thanks in advance

Paul
#91300 emp started

Kit number 1300, how cool is that?

Enlarge the jig, let the ribs set the size of the HS, not the jig. You will learn to trust the parts, they just fit so well I'm stunned every time I work on my -9.

Trust

Bill,
I'm already sometimes wondering why we fit all this together and then drill things to correct size. Everything lines up so well it's amazing. I really thought that enlarging the "fixture" was the correct thing to do, but since it's my first, I thought I should ask.
I figure after 1300 they have it right!

Thanks and have a great Thanksgiving.

Paul
91300

Paul,

The reason you match drill them is to stress relieve the structure. It is possible to just go and dimple the parts w/o match drilling as there is a very good chance you could cause a lot of cracking down the road.

I once asked Van's why they don't punch and dimple the parts at the same time and they said it was because of the 51% rule. My next statement was then why not match dimple the wings, fuselage, etc. and make the builder just dimple the tail kit. They didn't have an answer for that. Who knows, the RV-12 builders might get lucky on that score.

Ok, time for me to get down in the basement and finish fitting the 2nd wing tip.

Happy Thanksgiving!

common issue

Getting the ribs to fit in there is a common issue. You have to work at it, and it'll be worth it to spend the time and get it perfect. Don't get in a hurry here.

1) make sure you have the flanges on the ribs 100% perpendicular.
2) You'll notice that the forward edge of the flage is a bit flattened out (i.e., doesn't curve nicely as the rib curves to a point). It's OK to lightly relieve this a bit on a belt sander if you have to. Just roll the rib over a belt sander with light paper on it.
3) Press the ribs into the skin very firmly. Press pretty hard and align those holes. Resist the temptation to pry them in there with clecos.

The benefit of taking your time here is that you won't have a pucker in the LE that you'll get if the ribs aren't right. Down the road, you'll appriate the time you took because you're HS will be perfect!

Good luck, and keep pounding.

Fiddler
9612S