BalsaGlass Composites for Mid Power?

[Elapid]

i was thinking of making a composite of two sheets of balsa with some 3/4 oz fiberglass for a core. use *just* enough resin and using saran wrap to keep it from sticking to anything, lay a sheet of plywood on top of that and then stack a few 100 lb of weight on top and check it the next day.

I am considering this to try to save weight.

has this been done before?

thanks!

 

[wwattles]

You'd be sacrificing one of the purposes of the fiberglass, which is impact resistance/surface strength. Yes, it would be stiffer, but not as smooth. If you're looking at the world of composite construction for weight savings, try Giant Leap Rocket's Fins. It's a honeycomb that is lighter than solid fins, but also stronger.

WW

 

[Elapid]

Originally posted by wwattles
You'd be sacrificing one of the purposes of the fiberglass, which is impact resistance/surface strength. Yes, it would be stiffer, but not as smooth. If you're looking at the world of composite construction for weight savings, try Giant Leap Rocket's Fins. It's a honeycomb that is lighter than solid fins, but also stronger.

WW

i'm not after impact resistance or surface strength, i just would prefer the fins stay ON the model and that the model goes as high and as fast as possible on the smallest powerplant.

as far as balsa fin surfaces not being smoother than fiberglass, i think that depends on the quality of finish. so that's a toss-up.

i have considered several methods; a 1/2" strip of fiberglass along the leading edge of the fin might be sufficient, but makes finishing problematic. folding a full width of fiberglass and covering the entire fin surface would be structurally superior, but the weight would be at a maximum. then i though t of two 1/16" balsa sheets with a fiberglass core. it might supply enough strength to the balsa to keep it structurally sound at high accelerations and velocities. having the fiberglass at the core would make it easy to get a nice leading edge that wouldn't be easily damaged.

oh well...
i'll pick up some balsa soon and give it a go!
thanks for the reply!

 

[Stymye]

why not just use g-10 and thru the wall construction.
you can easilly break mach with that combination

fiberglassing balsa or the balsa/glass sandwich does not sound like the best route to me. seems the fin would crack either internally or externally quite easilly.be sure to post your results
on that either way

 

[kgholloway]

I've heard of using fiberglass resin, with or without a layer of thin cloth, for bonding two sheets of thin plywood together. The plywood is pressed between two sheets of plate glass during the curing process resulting in an extremely flat sheet of plywood for use as fins on HPR airframes.

As for balsa I've not heard of it being used in a like manner. At one time, however, there was a company making a type of plywood out of balsa. I had a chance to look at and feel some of this so called "balsa-ply" and I was impressed with it's light weight, stiffness, and extreme flatness. Alas, like so many dealers in hobby supplies, the company was in business for only a few years.

IMHO the best use for fiberglass and balsa is in constructing the relatively thick "wings" found on many early missiles like the BOMARK. The balsa can be sanded to a scale profile and then strengthened by applying a layer of thin fiberglass to the surface of the wing.

Ken Holloway, NAR #78336

 

[cls]

for mid-power you can make your own balsa ply. if you want to end up with 3/16", put 3 x 1/16" sheets together. laminate at right angles, at least; with 3 sheets you could go 0-45-90. use wood glue cos it's easier, cheaper, and strong enough.

doesn't need epoxy or fiberglass inside.