RV-7 Wing Leading Edge Problem

[milliken23]

Hello,
Can anyone help? I'm building the leading edges for my wings and after cleco'ing the first skin, i've noticed some interference from the ribs underneath. When the cleco's pulled everything nice and tight, there are small raised dimples from the ribs underneath. The cause of the interference is the rib web/flange at the second hole, where there is a hefty bend being introduced on the top side of the airfoil. I'm almost certain this is just aesthetic, but nonetheless it's bothering me. I could remove some material from the flange and sacrifice some edge distance to eliminate the high spot underneath. I'm sure i'm not the first person to run into this and would like a few different perspectives on the situation. In the attached photos, you can see the raised dimple between the first and second leading edge cleco's, it is consistent with every rib (you can see it in the second row of cleco's). The photo of the rib gives a good idea of where the interference is coming from, it is the high point at the right side of the picture at the end of the solid portion of the flange before the flange becomes notched for the tight leading edge radius.

[KayS]

i had the same thing, but i saw that later on my leading edge when i riveted the assembly. i'm very sure that this is only cosmetic and i wouldn't sacrifice edge distance to fix it. and i believe that it's not necessary anyway, because it should be sufficient just to slightly smooth out the bubbles at the notches on the ribs. i would try that and if it doesn't help i would leave as it is and not look back.

[RV7ator]

Cut away or simply grind down the offending flange end aft of the relief notch. Giving it a nice taper with the deburring wheel works for me.

While I'm thinking of it, when you position the LE's inboard rib and joiner strip, set the rib 1/16 or so more inboard then the plan's dimension. Otherwise the holes you drill will be so close to the rib web that dimpling and riveting will be difficult.

John Siebold

[bruceh]

I also hit my leading edge and tank ribs with a quick pass on the scotchbrite wheel just to round out the shape. Worked fine. Wish I had done the same on the HS ribs.

[milliken23]

Thanks for the inputs. I'm going to disassemble and take down the flange a little. I think i've got plenty of room to cut (3/32nd's) until i start running into any issues with edge distance. I can run the rib across the scotchbrite wheel to get a good radius on it, if cutting back the flange doesn't fully solve the issue.

Cheers,
Glenn.

[flion]

I'm having a hard time seeing it in your photo but if it's the typical rib-caused dimple, then smooth the notch in the flange at the flange/web bend. Due to the forming process, that often sits proud of the flange. You can also enlarge that end of the slot to a 'keyhole' shape, allowing you to bend the slot edge of the flange slightly for a better fit, and without enlarging the whole slot and reducing edge distance. A final option is to reform the flange slightly; I've had good results on the -6A where a lot of ribs needed work by using a flush rivet set in a gun on low pressure against a cheap anvil. So far on the -10 I haven't had to resort to more than the first technique.

[rvbuilder2002]

I think chapter 5 in the construction manual addresses this (adjusting the shape of ribs at the nose end)

[milliken23]

FLION,
I think that's exactly correct. It's actually the web thats causing the dimple. Although the flange is proud as well it wouldn't be the culprit, as it would have a desire to lay correctly inside the skin (and it's been fluted properly) Keyholing the notch and a quick dance across the scotchbrite wheel should do the trick. This is just a case of inexperience, now i've seen it and have a few good routes to go to solve this next time. My build is going to be very long, i spend 30 minutes planning, hemming, hawing, and 5 minutes actually in the execution of "building" the plane. Vans will have an RV-20 by the time i get airborne.

Cheers,
Glenn.