how many nutplates on W-704 wing bottom skin to F-776 center section bottom skin?

[Desert Rat]

When you build the wings, drawing 12 shows leaving every other rivet hole open in this area for nutplates/screws. That's what I've got.

When you get to the point after the initial wing mate where you match drill the center section lower skin to those holes, drawing 38 shows every 3rd hole open.

I called Vans yesterday and Tech Support opined that the best thing to do was see where the pre-punched holes fall in the part of the F-799 wing root fairing that lines up with that area and match to that.

It wasn't until after I hung up the it hit me that obviously that can't work. At least on the RV7, the F-799 doesn't extend that far aft on the lower side and has nothing to do with this area.

I'll call tech support back tomorrow and see if I can get clarity here but I'm surprised that a search here didn't turn anything up. Surely with 2,000 RV7s flying I can't be the first person to notice this. Has vans ever clarified this for somebody here?

[Richard Connell]

Too long ago. Can’t remember.
Are there any holes in your fuselage bottom skin now?
I vaguely recall there being no holes in the fuse bottom skin and using a strap duplicator to drill it based on the open holes in the wing (whether every second or every third)
I doubt it matters whether it’s every second or third. If you decide to make it every third you’ll only have to drill a handful of rivets out. They’ll get drilled up to #8 anyway so no big deal.

[Desert Rat]

If I decide to go every 3rd, I agree that it's not a big deal from the standpoint of the actual task, but I would be another cycle of pulling the wings off and then putting them back on and I won't have help for that until this weekend, nor do I want to do it just for the sake of a different rivet pattered for a few fairing rivets.

There are no holes in the fuselage center section skin. You match drill it to the wing via rivet holes you leave open in the wing root rib flange. Thats the question. One drawing shows leaving every other rivet hole open for match drilling, and the other drawing shows leaving every 3rd hole open.

Honestly , I doubt that it matters either, but such a blatant engineering discrepancy bothers me. Especially when I see that the same engineer drew both prints and they've been like that for years.

[wirejock]

Originally Posted by Richard Connell

Too long ago. Can’t remember.
Are there any holes in your fuselage bottom skin now?
I vaguely recall there being no holes in the fuse bottom skin and using a strap duplicator to drill it based on the open holes in the wing (whether every second or every third)
I doubt it matters whether it’s every second or third. If you decide to make it every third you’ll only have to drill a handful of rivets out. They’ll get drilled up to #8 anyway so no big deal.

I remember the same. There were holes on one or the other and just needed a method to match drill.

[D-Dubya]

Well, the 799 wing root fairing does in fact extend that far aft, but only for one screw. I think what Van's was trying to tell you was to match up that one screw and work backwards from there. On my 7, I don't remember if I used every third or every other screw, but I don't think it's that critical. I'll defer to Van's for that engineering discussion.

After you've mated the wings and drilled the rear spar bolt, that's the time to drill the missing holes that go through the fuselage bottom skin. As I recall, I drew perpendicular lines through each empty rivet hole on the wing skin, then made a hash mark 3" back. When the wings are mated to the fuselage, you carry that scribed line from the wing bottom to the fuselage bottom skin, measure three inches, and drill. Since you'll upsize the hole for the screw, it won't hurt if your hole is not spot on. Of course, you have to do all of that marking BEFORE you stab the wings. I believe it describes this in the plans, but sometimes these things don't make as much sense until AFTER you've seen it all put together. It's too late then. You have to pull it apart, make the lines, and put Humpty Dumpty back together again.

If you have to wait for a weekend to get help, then do that. Don't risk creasing a skin or otherwise damaging it over a few days.

[Desert Rat]

discussed with vans this morning and Eric at Tech Support told me that either pattern was acceptable. No insight on why the discrepancy.

Honestly, I figured as much, but now we've got it saved on the internet in case the question ever comes up.