RE: Sheeting Foam Wings
OK all you vacuum bagging experts...let me know your opinion here.
I recently received one of ACP's vacuum pump starter kits to use on my winter building project. The other night I decided to "practice" sheeting a piece of foam with some scrap balsa before I try sheeting the real parts and screw something up. Here's what I did:
I used some old scrap pieces of 1/16" balsa sheet, edge trued them, taped them together to fit the foam part. The foam part is a leftover piece of hatch-cover a buddy of mine had laying around. I thought it would be a perfect practice piece
I spread a very thin layer of ProBond over the wood...scraping off as much as I could so that the wood had a satin finish...didn't look wet.
I then put the wood and foam piece back in the shuck and put the whole assembly into the vacuum bag and let the pump do it's thing.
When I assembled the bag, I only put a small piece of breather material under the tube fitting....not all the way under the foam part. The pump is also preset to deliver 7" of vacuum. I let everything set for 24 hours.
When I took the part out of the bag, everything looked great...and I was pretty pleased with the results. However, I did find one area along the tightest curve of the foam where the wood never bonded to the foam. I actually noticed this while it was in the bag. The wood didn't want to bend tight enough to sit on the foam. I tried to coax it into position but was afraid of cracking the sheeting.
So I guess my question is, is this normal? Should I be concerned about small areas like this that don't bond well? If it will cause problems, what is the best way to fix it?
I don't think it will be a problem on the wings and stabs as the wood won't have to conform to as tight of a curve as my test piece.