Beach Shoot #13 - Helicopters
Date: 2003-11-22
Description
Three 9 mm ID, 50 mm long cases, plugged at each end with wax treated cat litter, one end recessed by the ramming nipple about 8 mm.
Propellant of straight BP meal in two of them, 10% spherical Titanium in meal for the third. Rammed using a case extender to completely fill the case, and add the flush end plug.
The spin/lift vent was drilled using a 1.8 mm drill, just above the flush end plug. There was no fire-proofing attempted. Fused with thin blackmatch and meal-NC paste as usual.
The stabilizer/wings were implemented a little differently than the previous device. As their only purpose is to prevent the device flipping over in the first instant of ignition they have become simply a bamboo skewer pushed through a hole drilled in the tube walls just above the plug in the recessed end.
The spin/lift vent points down somewhat, a little less than 45 degrees, so the majority thrust is dedicated to spinning not lifting.
Comments
Worked great!
Some difficulty was had getting the fuses to burn well, the weather had been foul in the early evening, so the ground was wet. Bare thin blackmatch always has this problem, chinese fuse, or real visco would not be affected.
The video for the Titanium one was lost accidently. A great shame, it was a very beautiful effect. Crackling Titanium sparks, rather like the previous Titanium stingers, just more sparse. The device peaked and came about half way back down before burn-out, perhaps due to the wind, or maybe the nozzle enlarged a lot from the high temperature combustion of the Titanium. None of the devices were recovered so this hypothesis can't be tested. I will try again with a waterglass soaked tube in the future.
The straight meal devices flew very high, around 40 metres with a pleasing humming sound. Still frames from the video show the spinning vent tracing out pretty sine curves and circles depending on the viewing angle.
1.4G commercial helicopter devices often have 'aerodynamic' wings, but their actual effectiveness is questionable. My devices are designed to fly only by their thrust output with no aerodynamic assistance. Perhaps with real wings my units would fly higher, but they already make good heights and achieve very high RPM because of their relatively low air resistance.
Attachments
| title | type | size |
|---|---|---|
| Test Video #1 | video/x-msvideo | 583.456 kbytes |
| Test Video #2 | video/x-msvideo | 457.328 kbytes |
| Pre-Test Picture (all three devices) | image/jpeg | 43.824 kbytes |
| Pre-Test Picture (device detail) | image/jpeg | 43.545 kbytes |