Beach Shoot #18 - 2 Stage (Fe and Ti) Wheel with Report
Date: 2004-01-03
Description
A fairly conventional 2 stage wheel using 9.5 mm ID, 50 mm long drivers. The driver end plugs were of wax treated cat litter, a 2.5 mm hole drilled just into the grain from each end, one for the nozzle, the other for the passfire.
A fairly small (about 35 mm per side) paloma was added as a terminating effect, it contained a small amount of +20 mesh pulverone.
The first driver composition was:
90% meal (not my fastest stuff, using pine charcoal)
10% steel (skylighter sparkler grade, linseed oil coated)
The second driver was similar, but using 10% spherical Titanium instead of the steel.
The hub was constructed from a piece of heavy cardboard, of which I laminated two layers with hot-melt glue to improve the stiffness. The two drivers where matched together with a length of quickmatch nosed using masking tape instead of a neat kraft nosing then hot-melt glued in place. Forgive me, I was in a rush.
Finally the paloma was glued to the hub and matched to the final Titanium driver passfire, with lots more masking tape to prevent preignition from the effects sparks. Meal-NC paste priming was used as usual on all matching.
Comments
Worked OK.
The steel driver offering a very nice effect. The thrust was perhaps a little low, but the duration was good for only a 2" long driver. The driver seems to be quite stable, no chuffing or other signs of distress like nozzle slagging. The camera undersampled the rotation with a fast shutter speed so it looks a little weird on the video, human eye's persistance of vision makes the effect look more like a solid disk of sparks.
Unfortunately on the first attempt the passfire between the drivers failed. When I opened the match pipe with a scalpel back in the shop I was suprised to find the match had gone about about half way through. I've never experenced this before. The blackmatch was fairly thin and when the unburnt piece was tested it was found to be pretty poor quality. In future multiple strands will be used to realiability.
I built a special adapter for my rocket launching stand so I could take this wheel to the beach site for better safety and viewing. This proved to work quite well, despite being a little large to carry around. It supports the wheel 2.5 metres off the ground so no effect is lost.
As I didn't feel like lugging the stand back to the beach to try the second driver, and it was too late to just make another Fe driver and try the entire wheel again I decided to cautiously shoot the remaining driver on the balcony.
This worked fine, but the effect was spoiled by the small space available there. The Titanium sparks throw many metres from the wheel hub.
Note the redish residue on the Titanium driver nozzle, I am not really sure what compound this could be? The Steel one just left a grey-black dusty residue. Both had the same form, flung out by the rotation. There was virtually no burn marks on the hub or support structure, the effects seemed to be well contained to the plane of the driver nozzles.
Attachments
| title | type | size |
|---|---|---|
| Test Video (Fe Part) | video/x-msvideo | 1.370 Mbytes |
| Test Video (Ti Part) | video/x-msvideo | 2.239 Mbytes |
| Pre-Test Picture | image/jpeg | 49.039 kbytes |
| Post-Mortem Picture #1 (End of Fe Burn) | image/jpeg | 48.008 kbytes |
| Post-Mortem Picture #2 (End of Ti Burn) | image/jpeg | 49.208 kbytes |