I figured it was fairly ambitious to try carrying a payload using one of these tiny stingers, but I had to give it a go.
The 8mm ID tube was cut 50 mm long, and the bottom 30 mm filled just like the previous 37 mm stingers, but slightly more propellant was added, completely covering my rocket mandrel pin.
The propellant had been treated a little differently this time. I granulated it with water and alcohol, in much the same way as making pulverone, just without the dextrin binder. This makes it much cleaner to work with, the meal is so fine it blows past the rammer and cakes in the funnel.
Next I rammed about 8 mm of D1 Glitter composition as a delay element, and a clay plug to within 4 mm of the top of the tube. A passfire hole was drilled at the side of the bulkhead, down into the delay composition.
An 3 turn overwrap of PVA pasted heavy kraft was added, extending the tube to 70 mm. A 1/4 teaspoon of -20+40 mesh pulverone was added as a break and the end filled with Granite pumped micro-stars (about 4 mm diameter and 4 mm long). A little -40 mesh pulverone was used to fill the rest of the heading and the top closed with some wadding and crimping over of the kraft with extra PVA.
The spin vent was drilled and fused as with a conventional micro-stinger, using a piece of thin blackmatch and meal-NC paste.
Didn't make it off the ground.
It spun up a little and left the launch pin, but fell to the ground. Once the glitter delay burnt through the payload was activated spewing flaming granite stars out on the sand.
Unfortunately the break isn't on the video.
The launch pin was melted and bent in a most odd manner. Once I washed the slag off it I found it very hard to bend back into shape, the steel was hardened. I'll have to chop off the end to reuse it.
The motor had some other issues. When I drilled the spin vent I missed, and drilled into the nozzle. I redrilled into the propellant, but the weakness right next to the spin vent caused the spin vent to enlarge much faster than usual.
The weight and length of this micro-stinger was just too much to expect much else.
| title | type | size |
|---|---|---|
| Test Video | video/x-msvideo | 398.090 kbytes |
| Pre-Test Picture | image/jpeg | 58.655 kbytes |
| Post-Mortem Picture | image/jpeg | 38.949 kbytes |