J

jdmunzell

Well Known Member
Hey guys,

This may seem rather simplistic but I have a pretty basic question. On my wing plans (dated 2001, matched hole, prepunched), the text states you cleco the skins on the skeleton (after mounting on jig) by clecoing every fourth hole. I have done all that and the structure seems to fit nice and tight...as it should! The plans text then reads that you begin drilling the skins by starting at the top in the middle of the skin and begin working down and out and smoothing out any slack!

Is this a throwback to when the ribs weren't matched hole? I have no problem starting my drilling wherever I am supposed to, but it seems that this structure all clecoed together every four holes has pretty well taken that procedure out of the loop.

Thoughts?
 
Jeff-
I drilled the wing skins the way that van's says to. The way I figure it is drilling them "down and out" removes some of the possibility of 1) developing oilcanning, 2) keeping the trueness of the wing and most importantly, 3) One less thing for me to worry about. I figured I worked too hard to make my wing perfect in the jig, and I gotta drill each hole anyways, so why not do it Van's way? The only downfall to this is keeping track of what you have and have not match drilled. I used a sharpie, which means drilling, putting the drill down, marking where I was, picking the drill up, repeat.
 
It takes a little more time, but you really should put a cleco in each hole as you drill. This hold the skin flat and helps with the migration of the skin.
 
Mel said:
.....It takes a little more time, but you really should put a cleco in each hole as you drill. This hold the skin flat and helps with the migration of the skin.
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I understand that logic, but wouldn't having a cleco every four holes through out the rest of the skin prevent that migration??
 
Not necessarily. The idea is to let the skin migrate from the upper middle toward the lower corners. The skin can still move ever so slightly with the clecos. The migration really occurs with the riveting. So it is not as critical in the drilling.
 
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Thanks Mel. That answers my question. You also bring up another point. I assume it's still a good idea to have heat (such as a heat lamp) on the skins while riveting to minimize or prevent oil-canning?
 
I heated my wing skins with a "salamander" heater. I used a lot of heat, so much so that I got a mild sunburn. This was overkill, but my wing skins are drum tight. It is not necessary, but like I said before, every little bit helps. BTW, if you do heat the skins, be sure to apply heat to the entire skin at once and not just "spot".
 
Warp?

Mel,
Interesting point you bring up but shouldn't the frame skeleton be heated up too? If you heat the skin it expands. You then rivet to a cold structure and when the skin cools off to the structure's temperature. it shrinks. Seems like you're loking for a warped wing. What am I missing here :confused:

Regards,
 
The idea is to heat the skin without heating the skeleton even though you will get some heat transfer. This is what makes the skin tight. It will not move enough to "warp" the wing. If the skeleton AND skin are at the same temperature, you have accomplished nothing. BTW, the wing should be jigged while the skins are being riveting.
 
So if one drills the skins in the summer am I safe to assume the riveting should be done at close to the same temp. (or warmer) as when drilled? I drilled all my skins late summer-early fall but have not riveted all of them yet (waiting for a helper) should I wait until summer if I don't want to heat it with a salamander?
 
Mel said:
The idea is to heat the skin without heating the skeleton even though you will get some heat transfer. This is what makes the skin tight. It will not move enough to "warp" the wing. If the skeleton AND skin are at the same temperature, you have accomplished nothing. BTW, the wing should be jigged while the skins are being riveting.
Click to expand...


Mel,

This thread came at the perfect time because I am about to rivet on my top skins. I warm my garage up to about 55 while working in it, but the skins are probably closer to 30 degrees (garage temp before heater). Do you think that a propane tank-top radiant heater aimed at the skins while clecoed/riveting would do the trick? If I am thinking right, the skins should absorb the heat quite nicely that this thing kicks off. I had something like this in mind:

mh12twhite.jpg


Thanks for any suggestions.
 
Just be sure you can heat a large area of the skin at one time. Don't "spot" heat the skins. If you can't make sure this is happening, don't do it at all. You could make it worse.
 
Mel,

I heated the skins during the tail feathers process and was quite pleased with the end result. I notice however that in the Orndorff videos, that this is not done or otherwise emphasized. Did the Orndorffs do this or was that ( in the videos) just for expediency of getting through the process in an expeditious manner?

Sounds like another heater might be in order to keep the whole skin warm.
 
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