Manufacturer: | Scratch |
Brief:
This is a simple mid-powered pyramid that flies on either one 29mm motor and/or three 24mm motors. The finishing
matches the construction materials--'el cheapo'.
Construction:
The parts list:
I started by attaching the cardboard triangles to form a pyramid. These were attached with epoxy and the joints were covered (hidden) with duct tape. The motor support plate was a scrap piece of 1/4" plywood. Before this was attached, I located the motor tube locations and drilled a hole for the lug. As the plate was epoxied into place, I measured the distance to each corner to make sure it was even. To find the location of the launch lug hole in the top of the pyramid, I dry-fit a 1/4" lug and used a rod to start a hole. I finished the hole with a hobby knife. After the lug was attached, I cut it flush to match the angle of the pyramid's side.
The theoretical CP of a pyramid is 1/3 of its height up from the base. I added lead shot to get the CG ahead of this point (as best as I could estimate). I now know from Bruce Levison's analyses that the CP is probably behind the bottom due to base drag effects.
Finishing:
There was no real finishing. To keep with the pyramid theme I found on on-line hieroglyphic translator and drew the
various characters with felt-tipped markers (very high class). The 4 sides say:
Flight:
This rocket has flown once on a G38 and once on three E9s. The G38 flight was nice and smoky with the low pressure
area at its base clearly visible. The E9s made for a slow boost and the rocket seemed to stop abruptly at burn-out. In
both cases, the pyramid fell nose first slowly to the ground.
Summary:
This was a simple, inexpensive, and fast build. Everyone who likes saucers, pyramids, etc. should build one. Not
necessarily exactly like this one. You can even paint it :)
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