Update #18 – Fabricating a Foam Paylod Container

I’ve had a few days to write this one up but I wanted to see how the construction held up before posting. I’ll offer a little explanation, some tips and tricks, and then post all the photos below. This construction technique is easy. Cheap too. It lends itself to unlimited custom shapes and sizes.

Sunday afternoon I had a big block of time, a mostly clear desk and a rough construction plan.

Starting with ‘raw’ foam, I used a wire-thin ‘hot knife’ to divide a single foam sheet into a top and a bottom. Then, I made straight cuts through blocks of foam to make 4 sides. These were secured with a glue that bonds foam to foam.

I wasn’t sure how well the glue would handle the temperatures and the stresses a payload might be subject to, so I cut down a long wooden dowel into about two dozen pieces. Using the hot-knife as a ‘drill press’ I made pilot holes to secure the top, bottom and sides using doweled butt joints. I used the extra pieces of cut-down foam to build some support in the mid-section of the payload container.

So far, GPS reporting doesn’t seem to be affected when placed inside a foam container. I’ll be running some tests with the container oriented about a dozen different ways, placed on the ground and in foliage to make sure we are are getting good position reporting after landing.

Q: Why not just buy a foam beer cooler?
A: You can. I still may do that. But a custom one allows me to control how much volume of dead space we have to keep warm. Also, it’s REALLY hard to cut foam from the inside of a purchased one. There is no room to get the hot-knife and two hands inside to cut spaces for the cameras or other equipment. When you build the container from scratch, you can get each of your walls right and then assemble the whole thing using your best constructed pieces.

Q: Is it watertight?
A: No more or less than cutting up a store-bought container. At this point, the foam is there for visibility, buoyancy, surface area for wind-resistance on descent and some structure to mount the cameras and GPS.

Q: Is this the final form?*
A:  Currently this container doesn’t have windows for the cameras and I am working through that particular issue over the next day or three. I’m mostly convinced this is the construction technique I want to use though. The size is probably 40% too big for ‘just’ two cameras and the GPS.

Regarding the current size:
Pro: A larger size could help with visibility, slowing descent if the parachute fouls/fails, and a larger container might ‘slide’ off of a tree better than a small payload that slips through a leafy canopy.
Con: More volume (dead-space) that we’ll have to keep warm and the increased surface area will leave us more vulnerable to wind.

IMG_6025-1 IMG_6027-1 IMG_6031-1 IMG_6030 IMG_6028-1  IMG_6032-1IMG_6034-1 IMG_6033IMG_6035

* ‘Choose the form of the Destructor!-Ghostbusters

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