1/2" spiral tube from calculator paper tape roll. Same as the KN/Silver gerb that exploded. Nozzle and bulkhead of cat litter, 5 mm nozzle bore.
A small quantity of meal was rammed first, as a primer, then the Fe/Al gerb composition. The gerb composition had shown no problems with ignition, so the meal probably wasn't needed. The composition was basically the wheel driver mix with added Aluminium flitters:
17 Potassium Nitrate
6 Iron (-100 mesh)
4 Charcoal (airfloat)
3 Sulfur
2 Aluminium (~100 mesh flake flitters)
Fused with meal/NC twisted tissue paper fuse, glued directly to the grain with a small quantity of meal/NC paste.
Good effect!
Well behaved burn, nice Aluminium flitter fireflys and long lasting iron sparks. Good burn time for such a small device.
The case held up to the punishment quite well. The thermal effects took about 20 seconds to soak through the case after burn out, although they were quite destructive, the outer layer charded and smoked a lot. The burn was well and truely over by the time the case integrity was at threat. A thicker convolute tube would be better in the future.
A large amount of iron-heavy (ie magnetic) slag was found inside the tube and encrusting the nozzle. The nozzle itself was slightly erroded, but otherwise withstood the abuse. It remained patent the entire time, I doubt there is a risk of nozzle obstruction in operation.
| title | type | size |
|---|---|---|
| Burn Video | video/x-msvideo | 4.287 Mbytes |
| Post-Mortem Cross Section | image/jpeg | 42.439 kbytes |
| Post-Mortem Picture | image/jpeg | 29.280 kbytes |