Beach Shoot #17 - 19 mm Stinger with 50 mm Ball Shell
Date: 2003-12-19
Description
Standard 64 mm long, 19 mm ID stinger missile motor using BP meal propellant.
No delay section, but a small spoulette-like delay in the passfire from the motor to the shell. I did not wish to make the device any more top-heavy than it already was by using a longer motor casing. While being top-heavy is good for rocket stability, it causes big problems for stingers during spin-up, they tend to topple off the pin and fly at acute angles with respect to the ground.
The shell was filled with my experimental KP/Zinc stars, each pumped to 5 mm diameter and length, meal primed. The burst was largely -20+40 mesh pulverone, but I added some -40 mesh pulverone to make the shell slightly over-full for tight packing.
The plastic shell halves were jointed with common plumbing PVC cement which seems to melt and weld the polymer they are made of quite well.
Comments
Kinda worked.
The stinger motor was a bit under-powdered for the fairly heavy (dense Zinc containing) payload. Even though I added a cardboard disk to help stabilize its spin-up, the device's top-heavy nature (and perhaps friction with the disk) caused the motor to topple before it achieved good stability.
As a result it went in totally the opposite direction to which it was aimed! Fortunately the delay failed completely, probably blowing through into the shell when the passfire hole was breached and the full combustion chamber pressure came to bear upon it.
The device only traveled about 30 metres horizontally before the shell burst, washing off most of the motor's speed before it could run out of beach. The motor section fell almost directly down from the break point. The next morning I was able, purely from review of the video, to walk to the spot it landed and recover it. The orange tape around the motor could be seen from hundreds of metres away in the dawn light aiding recovery.
The bottom half of the shell was still attached to the motor. The break had happened more or less completely at the joint, with only a small piece being torn from the lower half's rim. Clearly the solvent didn't weld the joint properly, I'll try xylene next time. The bottom half was in fairly good shape generally, only a few brown spots and melting near the join. The central passfire and delay section was completely burnt away however.
The top half of the shell was not found, in fact there was virtually no evidence of any fall out, no blown-blind stars, no shell casing fragments. Nothing but the motor and shell bottom just sitting there in a small impact crater.
The stars appear much greener in real life, the poor reproduction probably the result of the spectral response of the camera or its colour balance in low light conditions.
Attachments
| title | type | size |
|---|---|---|
| Test Video | video/x-msvideo | 800.036 kbytes |
| Pre-Test Picture | image/jpeg | 53.001 kbytes |
| Shell Assembly | image/jpeg | 75.965 kbytes |
| Post-Mortem Picture #1 | image/jpeg | 48.708 kbytes |
| Post-Mortem Picture #2 | image/jpeg | 45.900 kbytes |