Wing root fairing holes

[Brockster]

Hi, I am new to this site. I am currently finishing my wings for an RV-9A and have received my fuselage kit. Until recently I was unaware of this forum since I don't like to spend to much time on the computer. With family, work and a slow internet connection, I need all the time I can get to build. Looking at the previous threads posted it is amazing how many questions, problems, etc, are exactly the same I had during those stages of building. I can see what a very useful tool this forum is. My sincere gratitude to those who have the ability and are willing to take the time to document there progress on the internet.
I am almost ready to rivet my bottom skins on and am curious what others have done with the holes for the wing root fairings in the wing structure. Eight of the holes in the W-902 top skin call out to be machine countersunk. I suspect this is because the material thickness in this area is sufficient due to the skin, doubler and rib. The holes that will eventually be drilled in the T-901 tank skin for the fairing I assume will be dimpled. What about the remaining holes in the W-904 bottom skin and the top skin at the flap gap fairing. Should I drill and dimple these now for the #8 screw while the pieces are seperated or wait and locate root fairing and then dimple both skin and rib and skin and fairing together. My concern is, dimpling when they are together will be over .040" and you will be dimpling two pieces at the same time. Thanks!

 

[dgrayent]

Welcome aboard!

Yes, there is a wealth of information and good advice here. I am a relative newby, too. I LOVE this place! I've been spending entirely too much time here, maybe a couple hours/day for the last couple of weeks. But that's okay, I'm retired and the weather here in NE Ohio is too cold to work in my unheated barn. Basement work is progressing -- thousands of pin holes to fill in the cowling.... I hate glass work!! But it should be worth the effort when done.

About the wing skins, I suggest you leave the last wing panel off eachwing until much later (directions suggest that option, too). You will probably change your mind on some things like most of us do. There have been many times I have been in the wings for various wire runs, checking the pitot line, etc., etc. You can fit the wings to the fuselage completely -- sweep, incidence, ailerons, flaps -- the whole works with the last wing skin "not riveted on".

Wait until the wings are completely fitted before drilling, C/S, and dimpling for the wing/fuselage fairings. They are fitted with the wings on the plane and AFTER the wing is "final fitted" with sweep, incidence, flaps on, etc. That way the gaps and screw holes are in the right places.

With reference to where to dimple and machine C/S, as I recall and understand the plans, don't dimple in the fuel tank area. I presume the reason is to not distort the rib flange-to-skin area which might be conducive to a fuel leak if done. Basically, follow the plans even though they are a little difficult to figure out, but use key on the side and select the K1000, K1100, and the one leg platenut as suggested.

FYI, on fitting my wing root fairing platenuts, a couple (maybe 4) of platenuts had to have a small shim placed under one edge because part of the platenut rested on a rib flange or the trailing edge skin area (the one leg platenuts at the bottom (ventral) aft end of the wing/fuselage fairing). A couple more K1100 platenuts needed just a little ground off the edge to lie flat by clearing the flange of the rib.

Good luck,

Don Gray
Cortland, OH
N17QB 7A in progress

 

[Brockster]

Hi Don,
Thanks for the response. I am also building in the basement due to the cold. Hope I measured the stair well correctly when its time to get them out.(Wanted to insert icon here but couldn't figure out how to do it yet.)
Anyway back to the root fairing, I realize the K-1100's are dimpled and the K-1000's are not. It just seems strange to me when its time to mount the fairing that you must dimple two layers of aluminium at once, especially when it is so thick or does everyone leave the skins off until wings and fairings have been fitted. Also it calls out on the print to use K-1100's on the tank skin which I think means the tank skin gets dimpled. I imagine this area is pretty similiar on the 7 and the 9. You are right the prints are a little vague here. Just curious what others had done here. Thanks again.

Paul Dannebrock

 

[Derrell]

I agree with Don. I've set angle, incidence etc. & fitted the wing fairings & rubber bushings on my 7A QB. The bottom skins still aren't riveted on. It made it simpler to install the Trutrak servo in the right wing.
Derrell
RV7A Finish