Hey HBA,
I need a little advice from some of the composite gurus on the forum. Building an RV-10 has greatly improved my sheet metal skills, but I’m still pretty low level when it comes to fiberglass.
My next project is to build a composite overhead console/air duct that will ultimately be bonded into the cabin roof. Here’s a couple of pictures to give the general idea:
My primary goals are to
- make it look nice
- keep the weight low (the carbon console above weighs 2.5lbs)
- learn some new skills
- non-conductive so to avoid detuning nearby antennas
The plan so far is to build a sandwich style structure with 1-2 layers of glass on each side of a 1/8” PVC foam core. I’m thinking of using 2 plies (+-45, 0/90 or 2x +-45) of #120 3oz cloth on either side of the core. I also considered using a few plies of heavier 7781 cloth, but I’m not sure I can get it stiff enough without a lot of plies/weight.
I can think of two general ways to build the console. The first is to create a foam male plug and layup the first layers of cloth, bond in the core, and then layup the final layers of cloth. At the end I’d have to figure out a way to get the foam out. Alternatively, I could skip the plug and just make three pieces of sandwich board on the bench (two sides and a lid) and then bond them together in a secondary operation to form the overall shape. Any thoughts on one method vs. the other?
A related question for the “male plug approach” is whether to bond the console to the top itself during the layup or to mask/release it after the layup and bond it during a secondary operation?
Lastly, how fancy should I get with the layup itself? My tendency is to attempt either a straight wet layup or to make a between-plastic-sheets “pre-preg”. Using peel ply seems pretty straightforward as well. Is there a good reason to go whole-hog vacuum bag? I have a HVAC vacuum pump, but no other experience or tools for bagging, especially something this big.
Thanks for sharing your thoughts and experiences—still pretty green at this composite stuff.
David
I need a little advice from some of the composite gurus on the forum. Building an RV-10 has greatly improved my sheet metal skills, but I’m still pretty low level when it comes to fiberglass.
My next project is to build a composite overhead console/air duct that will ultimately be bonded into the cabin roof. Here’s a couple of pictures to give the general idea:
My primary goals are to
- make it look nice
- keep the weight low (the carbon console above weighs 2.5lbs)
- learn some new skills
- non-conductive so to avoid detuning nearby antennas
The plan so far is to build a sandwich style structure with 1-2 layers of glass on each side of a 1/8” PVC foam core. I’m thinking of using 2 plies (+-45, 0/90 or 2x +-45) of #120 3oz cloth on either side of the core. I also considered using a few plies of heavier 7781 cloth, but I’m not sure I can get it stiff enough without a lot of plies/weight.
I can think of two general ways to build the console. The first is to create a foam male plug and layup the first layers of cloth, bond in the core, and then layup the final layers of cloth. At the end I’d have to figure out a way to get the foam out. Alternatively, I could skip the plug and just make three pieces of sandwich board on the bench (two sides and a lid) and then bond them together in a secondary operation to form the overall shape. Any thoughts on one method vs. the other?
A related question for the “male plug approach” is whether to bond the console to the top itself during the layup or to mask/release it after the layup and bond it during a secondary operation?
Lastly, how fancy should I get with the layup itself? My tendency is to attempt either a straight wet layup or to make a between-plastic-sheets “pre-preg”. Using peel ply seems pretty straightforward as well. Is there a good reason to go whole-hog vacuum bag? I have a HVAC vacuum pump, but no other experience or tools for bagging, especially something this big.
Thanks for sharing your thoughts and experiences—still pretty green at this composite stuff.
David
