Beach Shoot #17 - More Meal Helicopters
Date: 2003-12-19
Description
Another three different sized helicopters. One 5 mm ID, one 8 mm ID, and one 12.5 mm ID, all 50 mm long except for the 12.5 mm unit which was 70 mm long.
All had wax treated clay end plugs. The 12.5 mm long device was built using an tapered end rammer, in an attempt to avoid the previous problem of nozzle hole expansion. The two smaller devices had a 1.8 mm nozzle hole, the larger unit a 2.5 mm one.
The propellant in each was BP meal. The wings/stabilizer were a piece of bamboo stick, 70 mm long, hot-melt glued in place. Each was fused with a piece of thin blackmatch and meal-NC priming paste. The thrust vector for each was 45 degrees down.
Comments
Worked OK.
The two smaller devices gave great performances, rising to about 15 and 30 metres. The wind carrying them north a fair bit, the 8 mm ID device landing in shrubs high on the cliffs where it could not be recovered. The 5 mm ID device was recovered about 5 metres from its take-off point.
The 12.5 mm ID device started out well, but about 1 metre up, it blew out part of its end plug. It fell back to earth and continued to burn for several seconds.
During construction only about 3 mm of clay was measured to lay between the end of the cavity and the bottom of the plug. Clearly this was insufficient to contain the internal pressures. I need more practice with my new tooling I guess.
Attachments
| title | type | size |
|---|---|---|
| Test Video (5 mm ID) | video/x-msvideo | 372.668 kbytes |
| Test Video (8 mm ID) | video/x-msvideo | 392.550 kbytes |
| Test Video (12.5 mm ID) | video/x-msvideo | 724.700 kbytes |
| Pre-Test Picture (5 mm ID) | image/jpeg | 36.743 kbytes |
| Pre-Test Picture (8 mm ID) | image/jpeg | 31.856 kbytes |
| Pre-Test Picture (12.5 mm ID) | image/jpeg | 46.510 kbytes |
| Post-Mortem Picture (5 mm ID) | image/jpeg | 51.147 kbytes |
| Post-Mortem Picture (12.5 mm ID) | image/jpeg | 37.685 kbytes |