Very similar construction to Bottle Rocket #1 and #2. Cavity depth was the same as #2, but the overall length of the rocket was reduced to 40 mm as in the previous flights it appeared the remaining propellant was contributing no thrust.
The bulkhead was hot melt glue only, the wadding was left out as it was thought to be unnecessary.
Little or no thrust was developed.
The rocket didn't even move as it burnt like a fountain for about 3 seconds. The difference in performance of this rocket and the previous two was staggering, and rather inexplicable!
The only thing I can suggest is that I used too much prime and the rocket end-burnt rather than core burning. Perhaps the cavity collapsed, but I would have imagined a containment failure would have been the result if that happened.
The postmortem revealed heavy stick charing, which is not suprising. The grain combusted completely and very cleanly, light could be shone right through the rocket, from the hot-melt glue seal to the nozzle. The nozzle end of the case walls were burnt much more than the bulkhead end, typical for end-burning configurations.
The nozzle was well preserved, minimal slagging or ablation. The first 8-10 layers of casing paper were basically destroyed by the heat.
| title | type | size |
|---|---|---|
| Burn Video | video/x-msvideo | 4.823 Mbytes |
| Post-Mortem Picture | image/jpeg | 48.345 kbytes |
| Pre-Test Picture | image/jpeg | 14.100 kbytes |