Building Tips and technical articles. > Building techniques
Foam core canopy/hatch treatment for testbed model
Bob Hunt:
Over in the All Amped Up section I have an ongoing thread about a testbed twin that I'm building using the "Lost Sheeting" method of construction (I'm actually going to change the name of that process to the "No BS Wing Construction" standing for "No Balsa Sheeting." But that's a story for another time and another thread. If you want to know more about it now, go to the twin testbed thread over on the electric section).
In the process of building this new twin, which is named Double Take, I tried to cut down on the amount of "good" balsa that would be required. I'm trying to save that good wood for actual contest models. When it came time to make a swoopy canopy for this ship I decided to use the Dow Buoyancy Billet foam that I normally use for my fuselage shell mold bucks. This material is very easy to carve and sand to shape. After carving and sanding it I decided to cover it with a piece of 1/2-ounce glass cloth applied with Z-Poxy. The next step is to hollow out all but about 1/16-inch of foam. I'm pretty sure that with the Z-Poxy and glass barrier, I can then apply a normal finish without dissolving the foam inside. Time will tell. Either way this is a good way to make a testbed model component part like a canopy/hatch. It may even be developed into a way of making full contest model components. The paradigms are a changin'...
Enjoy the photos... Bob Hunt
Crist Rigotti:
Another innovation from the Hunt shop!
Brent Williams:
The less B.S. the better! ;)
Nice work, as always!
Lauri Malila:
Bob,
Are you planning to cover the inside of foam canopy with glass cloth, too? With only 1/16" wall thickness it would increase the stiffness a lot with minimal weight gain. It would become a proper sandwich component. L
Bob Hunt:
Hi Lauri:
Yes, as a matter of fact I was just having a phone discussion about that very thing with a friend. This buoyancy foam is pretty stout stuff, and I think a 1/16-inch wall thickness with a layer of 1/2 ounce glass inside will work very well.
Thanks - Bob
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