Hyperdata Blog

Muzzle Velocity

A little video.

A couple of months ago I bought an air pistol with the hope of frightening away a vicious feral cat that had been taking chunks out of our cats. I was talked out of using it on the basis of “what if you get it in the eye“, and as it happens it would have been after the horse had bolted anyhow. But I’ve found it great fun for target shooting – I’m now inspired to try archery. (Yeah, ok, and it really brings out the 14 yr-old : you should see what happens to a cheese triangle, pure CSI).

Anyhow it’s also quite an interesting piece of engineering, so the natural impulse was to measure stuff. I twittered a few weeks ago for suggestions for testing muzzle velocity using household equipment. Quoll suggested (something like) firing through a disk spinning at a known speed, i.e. on a drill. Probably feasible, but I couldn’t come up with a good approach. The other day it occurred to me it should be possible to do using acoustics – record the sound as the pellet passes through things a measured distance apart. Perfect for a little diversion on a Saturday afternoon.

As it turned out the way I tried this had the impulses too close together to identify visually (overlaid with room reverb). I’ve not tried running FFT or anything over the sound, but I suspect it’s way too distorted. However I got rather a nice percussion effect, so played with Audacity and a sequencer a bit and made the backing track – no other sounds included.

In case anyone fancies trying a bit of analysis, here’s the original audio

1990′s?

There is a name for the style of dance Poppo’s doing which escapes me. : Bhuto. It developed from traditional Japanese dance styles, warped significantly after the bombing of Hiroshima and Nagasaki. A lot of improvisation – can’t see it on the vid, but he leapt off the stage onto a bunch of speaker cabs, a move that would have broken anyone else’s neck. Enjoy!

But what did you do in the 1970′s, Grandad..?

The Beast With Five Fingers

Name that tune (please!)

As I mentioned in March, there’s a little melody that’s been bugging me. It just appeared on CSI NY soundtrack, and although I wasn’t quick enough to record it direct I was able to whistle a very poor imitation (the version on CSI was whistled too). I’ve not captured the catchiness in the way it loops before you expect it, but hopefully it’s near enough for someone to recognise : Whistly tune

Bonus points if you can explain why it bugs me so.