Balcony Shoot #49 - Core-Burning Rockets with Payloads
Date: 2004-11-02
Description
As discussed in the previous test of this geometry I attempted to improve the propellant by moistening it and drying it out. Sufficient water was added to make the propellant just stick together when pressed and the resulting ball grated through a kitchen strainer, spread out and allowed to dry.
Free-air burning tests indicated a noticable improvement in performance. Three rockets were made, identical in geometry with equal mass to within 1 gram.
The first one carried a single 3/8" Shimizu Golden Wave star which was primed on one end with a batter of hot prime and a quick dip into -40 mesh Pulverone. A small quantity of 7/3 Whistle was placed in the recess at the top of the motor for an ejection charge. Some pasted ~50 gsm recycled kraft was wrapped around the top of the motor and twisted to a point to seal the payload.
The next device carried 8 KP Purple Organic stars, dusty meal primed. The break charge was -40 mesh pulverone surrounding the stars. A paper thimble (thin walled tube, crimped closed at one end) was glued and tied tightly to the top of the motor to contain the payload.
The final device carried one large D1 Glitter comet, about 25 mm OD and 20 mm long. A small amount of -40 mesh pulverone was put into the top recess of the motor to pass fire to the primed comet, and the comet held in place with a square of pasted ~50 gsm recycled kraft scrunched over the top of the comet and formed against the top of the motor.
All three had a conventional bamboo kebab stick for the stabiliser and a blackmatch fuse, although this time I did not use any priming to glue the fuse in, I just bent over about 10 mm of its length and forced it up the nozzle where it stayed by friction quite well.
Comments
All except the purple star device worked well.
The three of the rocket motors performed quite well. Better than the previous one with inferiour propellant, but I am still not happy, I think I'll drop the 6:3:1 to 6:2:1 and try again, or consider using better quality (and more scarse/expensive) charcoal.
The golden wave star was not caught on video, the rocket went basically straight up making following it difficult for my assistant. The beautiful tail of the star hung for over 5 seconds, but the star itself burnt out quite quickly, 12.5 mm or larger versions should be *very* impressive. I'll test some more in a stargun shortly, now that I have the priming worked out.
The D1 glitter comet was bloody beautiful, as usual! The camera did not do it much justice, especially as the rocket carried it quite a distance up and away from the observation point. I was a little concerned that it might burn all the way to the water being as large as it was, but instead it just put out a nice dense glitter tail for several seconds. I am getting more confident with large D1 comets, a 50 mm one would be interesting...
The purple stars blew blind *again* (See here and here). I just have no luck with purple stars! Back to the priming scheme drawing board for purples...
Attachments
| title | type | size |
|---|---|---|
| Golden Wave Rocket | video/x-msvideo | 566.758 kbytes |
| KP Purple Rocket | video/x-msvideo | 1.352 Mbytes |
| D1 Glitter Rocket | video/x-msvideo | 1.003 Mbytes |
| Pre-Test Picture | image/jpeg | 62.535 kbytes |