Balcony Shoot #26 - Hummer Experiments

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Date: 2003-11-05


Some new hummer tests using the 9 mm ID 50 mm long tubes from skylighter.

I made a case extender jig to assist ramming rockets and other devices, resulting in a 16 mm long off-cut of tube. I decided to try making it into a hummer, just for the hell of it. Thin (3-5 mm) wax treated clay plugs were rammed with meal in the middle as the propellant. A 1.8 mm vent hole was drill and fused with thin blackmatch and meal-NC paste.

Also, a 25 mm long version was made using a full 50 mm long case cut in half.


The longer device was great.

The shorter one didn't really get up to that high of a speed, or burn for very long, but it did work. Might be useful as an insert with Ti/meal propellant.

The 25 mm long verion was fantastic. It spun up to 1055 Hz in about 250 ms, consuming all its propellant in that time. Then it spun down gently over almost 5 seconds, the frequency domain curve nearing a beautiful exponential decay.

It is fortunate that just the enlarged hole rotating at those speeds produced an audible whine and documented the spin down so well.


title type size
Hummer #1 Video video/x-msvideo 885.256 kbytes
Hummer #1 Pre-Test Picture image/jpeg 11.298 kbytes
Hummer #2 Video video/x-msvideo 2.746 Mbytes
Hummer #2 Pre-Test Picture image/jpeg 43.994 kbytes
Hummer #2 Post-Mortem Picture image/jpeg 19.048 kbytes
Hummer #2 Spectrogram image/gif 141.449 kbytes