Sunday, January 23, 2011

Review: Boot Hill

This is a Halloween-themed oddroc based on a toy coffin. It features a 24mm mount and patented Coffin Lid Recovery.

The parts list:

* One pine (basswood?) coffin from Michael's
* Three wooden headstones, also from Michael's
* LOC 24mm tubing
* One spent 24mm casing
* Scrap plywood for internal baffle
* One screw eye
* Elastic and thin Kevlar®
* 3/16" launch lug

I slowly and carefully drilled a hole in the base of the coffin to fit the 24mm tube. A spent casing with the nozzle removed provides additional strength where the vent hole is located. The 24mm tube terminates on a plywood bulkhead plate that plugs the hole inside when the top is closed. The charge should push the lid open and hopefully the laundry will come out. An elastic shock cord attaches to a screw eye in the bulkhead plate. I also attached pieces of elastic and Kevlar® twine to keep the top from fully opening and breaking the hinges.

I made a RockSim model to check stability. I used circular components with frontal areas equivalent to the polyhedron shaped sections on the coffin.

Finishing consisted of painting the tube black and adding 'Boot Hill'-style inscriptions on the flip side of the 'RIP' fins:

Golden Scout #0869
"Lost in the NARAM-50 sky"
July 26, 2008

Birdhouse Version 2.0
"Turned into toothpicks"

Mini-Mojo Fat Boy
Died 9/21/2002
Rose from the grave 10/16/2004

Flight and Recovery:
I attached an 18" RocketChutes parachute to the shock cord and packed it in the upper chamber. Because there may be a leak around the bulk plate, I filled the remaining space inside the coffin with dog barf. The C11-3 was friction fit with masking tape. I also added a piece of masking tape to the leading edge of the coffin to keep it closed and opened the latch.

The boost was nice and straight and ejection was near apogee. The chute even came out! Because it was so tightly folded for a few days, it didn't fully open, but it was enough for a soft landing. The Boot Hill successfully flew a second time in this configuration. I guess coffin lid recovery isn't so bad!

I am happy to report that this model inspired EMRR contributor Claude Maina to build one of his own!

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