Hi to low wing mods.

[philipfrost]

Thanks in advance.
shoot me down on flames if needed. ( possibly a bad choice of words)

ive purchased a II high wing and converting it to low wing.
previous owner/s have removed the sheets from the wings, all of them...
for doing the wing upgrade.

some of them with a grinder, and made small nicks into the skins.

so, how bad is it to consider using CCP rivets for the skins.
how much does this affect turbulence, drag.
if money was no object I’d put new skins on etc.
but also atempting to line up the holes would be impossible.

your thoughts appreciated.

Next item.

the wing carry through spar on the high wing is flat.
on the low wing is 3 deg dihedral.
can you reuse the carry through spar, cut it and reweld with stiffeners.

again if cash was not an issue, new ones would happen...
also I’m remotely located, so every item is hard and expensive to get.
so we learn to use what we have if possible...

I also note the tail and elevators for the low wing are shown differently on the plan.
essential ?
advisable?

thanks again.

 

[M61A!]

As a Structures AME, I wouldn't use the existing skins, if there is much damage, but it might need a more careful assessment. How do you anticipate CCP rivets will work, if the existing ones were countersunk? They can't fill the countersink. I'm not really sure what you would achieve.
Match drilling a new set can work as long as it's done carefully (using the old skins as a pattern) and perhaps not as expensive as you might think.
As for the spar carrythrough, I wouldn't be cutting and rewelding the part of your aircraft that is taking the most load.

 

[philipfrost]

Thanks for info.
yes that all makes good sense.
sometimes you gotta get the obvious pointed out.

 

[Flyingfool]

Can you really use the old skins as an accurate pattern? Unless you completely flatten the old skins to lay out flat on top of each other. If you wrap the old skin over the new skin to mark the rib River holes. The thickness of the skin will cause a slight shift in the holes. Because the inner radius and outer radius of the two skins are different by the thickness of the aluminum skin.

Or is that shift so small it is irrelevant?

Perhaps cutting out strips for each rib location and label them. Then straighten/flatten them and locate them on the new skin. That way might be easier to work with. Then you would have all the remaining aluminum skin as extra materials.

 

[M61A!]

Can you really use the old skins as an accurate pattern? Unless you completely flatten the old skins to lay out flat on top of each other. If you wrap the old skin over the new skin to mark the rib River holes. The thickness of the skin will cause a slight shift in the holes. Because the inner radius and outer radius of the two skins are different by the thickness of the aluminum skin.

Or is that shift so small it is irrelevant?

Perhaps cutting out strips for each rib location and label them. Then straighten/flatten them and locate them on the new skin. That way might be easier to work with. Then you would have all the remaining aluminum skin as extra materials.

You have it correct.....you need both the new and the old laid flat. The slight difference if you wrap one over the other isn't as slight as you might hope and does shift the holes quite a bit.

Variations of your strip cutting idea can work. Polycarbonate sheet works well for templates. You can see through it to pick the hole underneath, but you still need to accurately transpose enough holes to attach your template.
It can be done, and quite well, but you need to be careful and think ahead, it's easy to make a mistake.

 

[Elviar]

I think if you're going to install new skins you could make a pattern gage and reposition the hole locations on the ribs using the techniques in the wing construction manual. You should have a couple of inches to work with between the flutes on the ribs. You might want to add a few extra rivets for location appearance and insurance. It would be prudent to check with Fred Keip, since he wrote the manual.

 

[philipfrost]

Thanks Elvira.
again good advice.

I can see Fred in the background, shaking his head.....
just read the **** manual......
I didn’t write it for my own good....
thanks Mr Keip.
im reading it now.