Balcony Shoot #23 - Core-Burning Rocket with Report

Date: 2003-10-31


A quick motor contructed to test a new batch of rocket propellant.

The new propellant batch was ball milled for 2 hours without the metal, then the metal screened in, tumble mixed for 10 minutes and finally granulated like pulverone to make it easier to ram:

18 Potassium Nitrate

6 Charcoal (-200 mesh)

3 Sulfur

2 Aluminium (-325 mesh, spherical)

The batch was sun-dried on the window sill over two days (about 3 hours of direct sun exposure total).

8 mm ID, 15 mm OD, 70 mm long, PVA pasted craft cardboard without overwrap. Wax treated cat litter nozzle and bulkhead, rocket was rammed on nipple only, core was drilled out after charging with a 2.5 mm drill. The passfire hole was also off-centre drilled with the same drill bit.

Only 50 mm of tube was rammed with rocket propellant and clay, the top 20 mm was left for a small quantity of -20+40 mesh pulverone, a piece of wadding and a thin layer of hot-melt to produce the report charge.

Standard bamboo kebab stick stabiliser and thin blackmatch fuse, glued in place with meal-NC paste.


Worked OK.

Flight path was rather erratic. It curved somewhat just after launch sending it in an unwanted direction, but it straightened up afterwards reaching an enormous height before the report was heard. The sound rather diminished by the distance from the launch point.

I am unsure of the cause of the flight path, perhaps some kind of instability or off-center stick placement. Maybe I drilled the core wrong, but I doubt it. Normally curving violently away from the launch tube is due to a stick bent away from under the motor casing, but this stick was very straight and parallel to the motor axis.


title type size
Test Video video/x-msvideo 281.064 kbytes
Pre-Test Picture image/jpeg 45.372 kbytes