Balcony Shoot #2 - Better Greenmix Test Rocket

Date: 2003-08-11


Kraft paper case, 15 layers taped, no glue. 8 mm ID, 50 mm length. 2.5 mm diameter cavity, 20 mm deep into grain. 8 mm thick plaster of paris nozzle with ~30 degree divergence cone. Bulkhead of paper wadding.

Greenmix propellant, but better quality than previous tests, hand made in mortar and pestle:

75% Potassium Nitrate

15% Lampblack

10% Sulfur

The motor was rammed over a piece of metal BBQ skewer as a mandrel. The drift was bored out with a drill to match.

Fused with loose greenmix prime and a meal-IO paper fuse taped across nozzle mouth.

Conventional bamboo stick for stabiliser.


Spectacular CATO.

Bulkhead and about 15 mm of the top of the case was totally blown away the instant the motor ignited.

The remains were not recovered until the following day, by which time a car had run over the case, crushing the nozzle and removing any chance of determining if a nozzle blockage caused the failure.

The case was fairly thin, it is possible that it simply couldn't withstand the combustion pressure. It is also possible that there was a grain void or other ramming problem, the tooling was very marginal to say the least.

The postmortem revealed creases in the inner layers of craft paper, which is usually a sign of poor ramming.


title type size
Rocket CATO video/x-msvideo 2.385 Mbytes
Post-Mortem Picture image/jpeg 33.695 kbytes