38 replies to this topic

[alex000]

About a week ago i made about 10g of whistle mix, i Lightly pressed it in to a tube and clay powder in one end and a carboard end cap the other with the fuse through the carboard cap.
I then lit it and it was quite loud.

Just now i have done the same, i lit it and it didnt go bang but it was very slow burning. It was almost like black powder that hadnt been milled. The mixture has been mixed well so what am i doing wrong.

Also after buying a 1lb whistle rocket tooling the rocket only manages 15ft off the ground even if it has been pressed well. Do I need to add red iron oxide to the mixture is:
Potassium perchlorate.............................7
Sodium benzoate...................................3

Edited by alex000, 17 February 2007 - 04:27 PM.

[Frozentech]

About a week ago i made about 10g of whistle mix, i Lightly pressed it in to a tube and clay powder in one end and a carboard end cap the other with the fuse through the carboard cap.
I then lit it and it was quite loud.

Just now i have done the same, i lit it and it didnt go bang but it was very slow burning. It was almost like black powder that hadnt been milled. The mixture has been mixed well so what am i doing wrong.

Also after buying a 1lb whistle rocket tooling the rocket only manages 15ft off the ground even if it has been pressed well. Do I need to add red iron oxide to the mixture is:
Potassium perchlorate.............................7
Sodium benzoate...................................3

Sodium Benzoate is slightly hygroscopic and absorbs enough moisture from the air over time to stop whistling, and reduce thrust. I would dry it before use, and make sure it's very fine mesh. For rockets, iron oxide or another catalyst are recommended.

[Mumbles]

I'm not sure if I read this right, but you milled whistle? In generally this is a very bad idea. It is much more sensitive to BP, and you will probably have an accident eventually if you keep it up.

For the rocket, iron oxide will help. Also just because you think it's pressed well, doesn't mean it is. Body weight is not going to be enough. 8800 PSI is the general goal to shoot for when pressing rockets, which you will need a decent press for. Ramming is not acceptable for whistle.

[alex000]

I'm not sure if I read this right, but you milled whistle? In generally this is a very bad idea. It is much more sensitive to BP, and you will probably have an accident eventually if you keep it up.

For the rocket, iron oxide will help. Also just because you think it's pressed well, doesn't mean it is. Body weight is not going to be enough. 8800 PSI is the general goal to shoot for when pressing rockets, which you will need a decent press for. Ramming is not acceptable for whistle.

I said it burns like non milled black powder. Thanks fot your advice, I have been using a clamp, but looks like i need a press.

[BrightStar]

There's an informative and fairly simple tutorial for making whistle here:

http://www.jackerypy...m/whistles.html

It's has some tips on common failure modes as well. The components must pass 100-mesh and granulation seems to be important. I wouldn't choose toluene as a solvent personally and haven't tried this recipe myself but will be doing so soon - I've been wondering if the granules would also be good as a shell break booster.

Edited by BrightStar, 18 February 2007 - 12:30 AM.

[BrightStar]

OK, I tried out a variation of the above whistle method...

Potassium perc: 70%
Sodium benzoate: 30%
Vaseline: +3%
Red iron oxide: +1%

The perc and benzoate were separately ground until they passed 80-mesh. The vaseline was disolved in excess Coleman camping fuel (purified petrol/gasoline) by shaking it in a closed jam jar until dispersed. This is less toxic than toluene but even more flammable - mix it outdoors. The benzoate and iron oxide were stirred in, then the perc added. The pink mix was spread out on foil and allowed to almost dry, then granulated though a 15-mesh screen and left to fully dry.

Taking a 4oz rocket tube of 1/2" id * 5" length, approx. 1/3 was filled with rammed bentonite, 1/3 with hand-consolidated whistle granules (35mm depth, 7.5g of comp), the remaining 1/3 was left open and primed with a dusting of green mix.

Video here:

Benzoate whistle (1,435 Kb divx avi)

Seemed to work well, but was not quite as loud as I had expected. It's an easy, workable method though...

Edited by BrightStar, 20 April 2007 - 09:38 PM.

[maxman]

Mad my first batch of 70/30 perc benzoate whistle mix. I have no idea how fast this stuff should be when made well, so I'm posting a video Here Can anyone tell me if this is normal speed as I thought it would have burned faster than this. If it is ok, how much for a booster in a 3" shell? Should I use a "whistle bag" or sprinkle in?

I hear it burns faster when confined like kp!?

[MMMMMM Pyro]

Yeah, that looks about right to me!
Also, thanks Brightstar, thats a really useful tutorial!

Regards,

Mike

[pudi.dk]

Gee, a little risky place to ignite, don't you think?

[maxman]

No it's ok really. It was raining outside It was only a small amount and I have taken precautions.

[sasman]

I have never used whistle to break a shell because i aways thought it didnt burn fast enough?... it burnt just like your test clip maxman.. i look forward to seeing your whistle perform in a shell...

[maxman]

Yeah I was expecting it to burn faster than meal, but it seems about the same to me and much slower than BP. I just wondered if I'd got it wrong! If everyone agrees that the speed is not slow for whistle then I can only assume that it burns faster confined. I'll just use it in a shell rather than test a report with it since I dont like making bangs in the garden however small and I dont have the enthusiasm to go to my test site to try a little one as the weather is so bad and it's depressing!

[karlfoxman]

That whistle will work, people seem to see it burn loose and think ah its awful. If you were to dump that powder into an open ended tube thats pluged at one end it would blow it up. Look at the amount of gas it gives off, very high volume of gas. It will burn faster confined, use about 5% whistle for the weight of the shell. So if the shell weighs 220g use 11.0g whistle. So long as its well mixed and the ingredients are both nice and fine it will burn good and fast.

[Wyvern]

I'm having the same problem with my whistle in the fact that its not perticularly loud, i made a small batch of Chlorate whistle which was slightly louder, do you think its the hygroscopicness (is that a word??) of the sodium benzoate that is the problem?

[maxman]

Chlorate whistle? Isn't that very dangerous? As far as I am aware you can't make chlorate whistle with sodium benzoate! It wont whistle.Dont take my word for it but that is what I've read elsewhere. It must be perchlorate. With regards to perc / benzoate whistle as I understand it the sodium benzoate itself is not hydroscopic but when mixed with perc, sodium perchlorate is formed which is hydroscopic.

Perhaps any chemists out there might like to correct me if i'm wrong

Cheers