28 replies to this topic

[Mumbles]

I looked around, granted not all that thoroughly. I found it for about $4 per pound, where as potassium benzoate is $1 per pound at the same quantity. This was in full 50 to 55lb bags.

[MDH]

In other news, Mumbles lives in the United States, and has it both extremely lucky and easy when it comes to pyrotechnics...

We wish we could get chemicals at those prices, mumbles (for some of us, let alone chemicals at all).

Edited by MDH, 14 April 2010 - 11:53 PM.

[BrightStar]

70 - Perc
20 - Benzoate
10 - Aluminum

Interesting that a hybrid flash / whistle works well in practise. It's something I'd though of but never tested. If it adds some of the 'boom' of sulphur as per Shimizu's triangle diagram without the added sensitivity it might be a winner.

Perhaps it's just me, but bright flake aluminum needs far too much confinement to do its job.

Which prompts the question, how much confinement is enough for aerial salutes? I'd always assumed that the stringing and pasting-in of bottom shots for example, was more about structural strength for the lift rather than report performance. Any thoughts?

[Potassium chlorate]

In other news, Mumbles lives in the United States, and has it both extremely lucky and easy when it comes to pyrotechnics...

We wish we could get chemicals at those prices, mumbles (for some of us, let alone chemicals at all).

You can in Europe too, though you usually need a VAT number. Most bigger companies don't sell to private citizens.

[digger]

Not everything is available cheaply. The one that infuriates me is Potassium Benzoate. This is expensive in Europe because most food companies use Sodium Benzoate so there is little market for the pot benz here. Even at bulk prices it can be as much as £6-7 per kg (if you can get it at all), ouch.

[rocketpro]

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Edited by rocketpro, 06 August 2010 - 11:00 AM.

[dr thrust]

hmm ive only used the potassium benzoate, it can be made to go well ,i tested somehere but had to use a longer than normal spindle, also on the vid is a perc bp fueled nozzle less motor, which managed to give out a sound of sorts, not that was my intention , so id presume a perc/potassium sorbate fueled rocket should give out some form of sound?

Edited by chris m, 15 April 2010 - 06:49 PM.

[digger]

Salicylate is the most powerful whistle I have tried, bloody hygroscopic though. I have had decent results with pot benz and sodium benz though. I did have to use the Coleman fuel method though to get a good mix.

I have to say the Pot sorbate seems the easiest so far. It would seem to have similar results to the salicylate just by screening (ok I used copper oxychloride catalyst rather than iron oxide).

However I will try a few motors in a couple of weeks to see how it flies.

I do have a few kilo's of salicylic acid kicking around so maybe I will knock up some potassium salicylate and maybe even some copper salicylate (although I guess that may turn out to be a salute on a stick).

Edited by digger, 15 April 2010 - 10:14 PM.

[Vic]

Which prompts the question, how much confinement is enough for aerial salutes? I'd always assumed that the stringing and pasting-in of bottom shots for example, was more about structural strength for the lift rather than report performance. Any thoughts?

Some 4” bottom shots would have ½” thick walls and sawdust or sand packed round this and the outer casing, also a cushion of paper wadding beneath the bottom shot and the lift on multi breaks to take out some of the shock on lift. By the way sand is to to give the shell more bottom weight to keep the orientation of the shell.

[MDH]

When it comes to nitrate flashes, you can never have enough. I twine them over, paste them, dip the entire thing in paste, etc.... With 7/3 it's almost a cheat because you need little or no confinement to produce an amazing sound with it. It all depends on what kind of sound you want of course - certain flashes will provide certain depths, and certain types of sound depending on how the gasses are allowed to escape.

I agree with digger on sorbate being the best. I've had a ten gram batched of it stored without a lid for nearly half a year now and it's still in perfectly good and usable condition, and is still as powerful as ever. I tried to use some as a fast-burning fuse and it still just "Exploded" no matter how well it was pressed inside of a narrow, folded over tube, so my guess is that it is too reactive to be used as a rocket fuel (I've had it pressed inside of a 1/4" thick, 3/4 ID, 1" long tube open ended out of curiosity and it created a purple-ish flare which burnt strangely slowly for a moment then exploded anyway).

[martyn]

I won't pretend to understand the chemistry, but i think the original youtuber must have seen this patent
http://www.patentsto...escription.html
I think that they are claiming the pentaerythritol makes the flash safer to handle but equally or more powerfull when confined.
For all I know, smarties would do the same thing.

[MDH]

They mention the terephthalic acid I had previously spoken of.

These create a saturation of a lower temperature fuel which prevents all of the aluminum from burning at once. But it is likely that the burning aluminum, inside of containment, heats the gas produced to significantly higher levels, which is what allows it to function so well as a report composition. It is very similar in function to nitrate flash.

Any number of organic chemicals can be used to do this. Slow flash outside containment is not a particularly new concept.

[martyn]

"Any number of organic chemicals can be used to do this"
So I was right about the smarties then .

Thanks for the explanation.

[dr thrust]

When it comes to nitrate flashes, you can never have enough. I twine them over, paste them, dip the entire thing in paste, etc.... With 7/3 it's almost a cheat because you need little or no confinement to produce an amazing sound with it. It all depends on what kind of sound you want of course - certain flashes will provide certain depths, and certain types of sound depending on how the gasses are allowed to escape.

I agree with digger on sorbate being the best. I've had a ten gram batched of it stored without a lid for nearly half a year now and it's still in perfectly good and usable condition, and is still as powerful as ever. I tried to use some as a fast-burning fuse and it still just "Exploded" no matter how well it was pressed inside of a narrow, folded over tube, so my guess is that it is too reactive to be used as a rocket fuel (I've had it pressed inside of a 1/4" thick, 3/4 ID, 1" long tube open ended out of curiosity and it created a purple-ish flare which burnt strangely slowly for a moment then exploded anyway).

hee hee , turns out pot sorbate makes a extremely good whistling rocket propellant, when prepared with Vaseline, check out the video in the nozzle-less rocket thread

Edited by chris m, 28 April 2010 - 10:56 PM.