Howler rockets?

[azure]

Does anyone know how to make these nozzleless howler rockets like the ones Dan makes?

 

http://pyrodan.privatedata.com/fireworks/34_howler.mpg

[Algenco]

it looks like a standard nozzleless BP with whistle fuel as the last few increments

[azure]

So is it the combination of the BP and the whistle delay that makes this ungodly noise?

Because when i use a whistle delay for lets say a strobe rocket, it sounds like whistle and doesnt howl like that 3/4 inch rocket from the video.

 

Here is a 6lb version from Dan

 

http://pyrodan.privatedata.com/fireworks/6lbhowler.wmv

Edited November 20, 2010 by azure

[WonderBoy]

I think it is because of the length of the tube, the longer tube gives a lower pitch. Dan makes his own tooling which usually has a narrower and longer spindle than most commercially available tools, so his tubes can be pretty long. One version of his 6lb nozzle less BP motors that he shot at PGI had an 18 or 22" long tube, I can't remember exactly.

[dagabu]

While the tube itself can help to change the timbre of the sound, it is actually the fuel itself that determines the pitch of the noise. Take a look at Danny Creagen's tests LINK . Dan Thames rockets have a pretty big ID and I think that it is the ID and not the length that makes the lower pitch in his rockets.

 

But then again, I could be wrong.

[azure]

Well that sounds plausibel except that the first video features a 3/4 inch rocket.

The length of the tube has some influence on the sound produced but when i compare my shorter 3/4 inch whistles with my longer strobe rockets, there isn't that much difference in sound frequency and amplitude when the whistle delay kicks in.

 

I was thinking that maybe the solvent used for mixing the whistle has something to do with it.

Like the chuffing of magnalium rockets that are still a bit wet of naphta.

 

Or it may have something to do with combining 2 or more compositions in a single rocket that differ substantially in burnrate and reaction products produced (solid vs gas , complete vs incomplete combustion etc).

 

Just speculations..

 

But these rockets sure sound awfully nice!

Edited November 21, 2010 by azure