"Tedstriker" wrote

Aren't the foams used in with epoxies a lot cheaper?

Yep. you can get a 4' x 8' x 1/2" sheet for about 10 bucks, take or give a
couple. Get some 2" stuff, too, for the corners. To bend it for the taper,
take a straight edge, and lay it perpendicular to the fuselage, and make a
series of cuts with a utility kife, about halfway through. Put the cuts on
the outside of the curve, and experiment on how close you need to put them.

But then
I've noticed that epoxy resin is more expensive than vinyl-ester.
Matter of fact, for a belly pod, I can just build it out of polyester
resin I can buy locally.

Heavy, isn't it? Gotta keep this thing super light, right?

One thing I wonder about is the exhaust.
A center mounted bomb pod would be between my exhaust pipes, but a
rectangular pod would be hit on both corners by engine exhaust. I
wonder if the heat would eat through the fiberglass?

I think you would need to keep the pod slightly back from the center of
gravity, to keep the aerodynamic stability, and the weight and balance still
close. Slope the back side way back, to keep that side area behind the
center of pressure. If the front were a couple feet back from the pipes, I
would think that the turbulence from the propwash would have mixed enough
air with the exhaust, to keep it cool enough. I would think that the worst
that would happen, is that it might soften the epoxy a little, but it gets
hard again when it is cooled off. The inside layer of glass would be kept
cooler, from the insulating value of the foam.

It might be necessary to put a layer of aluminum on the front of it. I
really don't know how much of an issue this heat thing is, but my gut
feeling is, not much. Anyone else got any idea? A pipe extension, perhaps?

Not sure which one would be more drag than the other. (Bomb pod type)

My guess is it would be close to a wash. A bomb pod has a mounting pylon,
and that is going to have intersection drag at two places. (the pylon to
wing, and pylon to pod) Wetted surface is low, but so is storage space.

The belly pod would have no intersection drag, and no more corners than
before. More wetted surface, but SO MUCH more storage. to me, that is the
biggest factor. Skis, tent poles, fishing rods, a few golf clubs, would all
fit in a belly pod.

Another thing you could plan on, is using the belly pod to hold some extra
tankage, for ferry flights. Gonna have to fly solo, with that option, most
likely. Make the top (side towards the fuselage) with a lightweight
removable panel (for waterproofing) and only include strong cross struts, or
tabs, for mounting it on the bolts to the plane. Gotta keep that weight
down, right? That way, you could drop the tank in through the top, and bolt
it up. You would need a electric fuel pump to transfer fuel.

Disclaimer: I am not an aerodynamic specialist, or an A and P. (or anything
else) Make all changes at your own risk, after consulting a specialist.
This is all more of a thought exercise, than anything else, for me. I did
stay at a Holiday Inn, last night! g
--
Jim in NC