8 replies to this topic

[Freese]

Hello:

I love whistle rockets, but I also like the tail effect of BP rockets. Is it possible to get a nice tail with whistle comp and NOT degrade performance (and not greatly increase the odds of CATO)?

Is it possible to get different colors from whistle comp? Again, without degrading performance or increasing the chances of CATO?

I have searched and not found any formulas. I've seen some mention of adding metal powder to the comp, (which seems obvious, but which whistle comp would work better, benzoate or salicylate? Which metal, Ti, Al, Fe, FeTi???) but nothing specific. I imagine adding any type of metal powder would increase sensitivity (I wouldn't even try Magnesium )

I have tried adding various barium and strontium salts to KClO4 + NaBenzoate mix. Burning open, loose comp didn't show any color. I can't experiment with actual rockets right now, the area I live in is in month ten of a long drought and I don't want to risk starting any wildfires. I guess I could do a static burn of pressed comp, if I can get colors, to test for performance degradation, but since I have no tools to test performance, it would be more for show (and to see if it CATO's).

Soooo, if anyone out there in internet land has any ideas, please share.

Thanks.

[FrankRizzo]

Joe Domanico and the pyrotechnics team at the Edgewood Research, Development and Engineering Center found that addition of up to 5% -325 mesh iron powder increases the burn rate of standard 73:27 potassium perchlorate/potassium benzoate whistle mix more than 18X.

[alany]

Wack a TT or similar comet on the top of the whistle rocket and match it to the main fuse.

18 times - that would make it nearly 200 mm/s. Rather explosive! I have some fine iron powder, I guess I could do the experiment. -325 mesh iron is fairly pyrophoric if it was prepared in a dry and oxygen deficient environment, so caution is advised!

[FrankRizzo]

Wack a TT or similar comet on the top of the whistle rocket and match it to the main fuse.

Now that's just cheating


Alan, the base whistle mix was measured to burn at approx 5.3mm/s. I suggest checking out this document on pages 498-505:22nd IPS Proceedings

On reading through it a second time, I may have been interpreting the data incorrectly. The numbers on the high oxidizer loading table on p.494 (503) really don't make sense with what is said above it. The control mix is said to burn at .207 in/sec on the previous page, with 5% fine iron powder increasing the burn rate by over 25% (.261 in/sec) with no significant decrease in peak amplitude (sound) of the whistle. But, on the high loading results table, the 5% addition of iron powder is said to increase the burn rate to 3.8 in/sec which corresponds to >18X the control rate, the copper oxide showing an even greater promise albeit with no spark effect. Possibly, they forgot to move the decimal pt and 3.8 should instead be .38? That's a pretty serious error to publish if that's the case.

Edited by FrankRizzo, 11 June 2006 - 09:25 AM.

[alany]

It sure looks like a mistake.

Another thing that worries me is the inconsistency between the High Loading results for 5% Black Copper Oxide and those in the Oxidiser results. Shouldn't they agree more closely? Even assuming a 10x error in the high loading ones 0.34 is significantly different from 0.303.

I've never tried to burn whistle mix with 50% by mass Copper Oxide, but I'd be very suprised if it still whistled at all let alone burnt well! I guess the only way to tell is to try it for myself.

[Freese]

Friday, I decided to do some experimentation.

I read somewhere that any metal oxide could be used for the catalyst (United Nuke has a formula using uranium oxide, and a warning not to do it), so I substituted the red iron oxide (why is it always red and not the black stuff???) with Copper Oxide (black). A loose powder burn showed no change of color. (Oh yeah, I'm using Na Salicylate, not NaBenzoate - would that make a difference?) But then, it burned so fast (like flash powder) that it was hard to tell. I increased the CuO up to 2%. Again, loose burn was a flash, showed no color change.

I decided to try a static test - pressed the mix into a 1/4"id tube (spiral), taped to a stick which I stuck in the ground. It ignited no problem, gave a shrill whistle and then CATO'd. (I couldn't find my 1/4" rod, so the press might have been off.) There was not even a hint of blue color.

I'm guessing (because I haven't looked at chemistry since high school) that the problem is either 1) not enough copper; 2) not enough chlorine; 3) blue, sitting at the cooler end of the spectrim, might not even be possible because whistle comp burns too hot. If that's the case, blue is impossible and it's on to green, but I don't know where to find BaOxide.

As I was sitting in my library (a/k/a wc, head, toilet) I re-read Lancaster and his book indicated that Ti could be used for tail effect in whistle rockets, but (as I thought) uit substantially increases sensitivity. I then found an independent formula calling for 5-10% Ti for tail on whistle rockets (with the sensitivity caveat).

Anyway, thanks for the ideas. Being somewhat new to pyrotechnics, and not having a chemistry background, I appreciate any help I can get - so I'll be making full use of the search function.

Thanks,

Fred

[FrankRizzo]

Fred,

Using sodium salicylate, you'll not see any color besides yellow. The color imparted by the sodium ion is so strong it overpowers everything else. You'd really need to use potassium benzoate to have any hope of coloring the flame.

[alany]

Re it exploding: Did you press it in small increments?

[Freese]

Re it exploding: Did you press it in small increments?

Probaby not small enough. The tube was the smallest I have on hand, spiral tume about 1/4"id x 1.5" long. I bought them to make spollettes. I just wanted to see if I could get any blue color with packed comp.

Probably right, packing was the problem, with such a small tube, I think I ended up with just two increments, and I didn't have the correct size drift for packing (of course, right after I finished, I found it), so I'm a bit surprised it didn't CATO right away. It did give me a whistle first.

I have some of that comp left. I think I'll try to add a bit more CuO, a bit of parlon and maybe a tad of some other copper salt (a bit = 1% ) and see if it still whistles (and just maybe give a hint of blue.) Then I'll give up on trying for blue, maybe go for green.

Fred,

Using sodium salicylate, you'll not see any color besides yellow. The color imparted by the sodium ion is so strong it overpowers everything else. You'd really need to use potassium benzoate to have any hope of coloring the flame.

AAAAhhhh, so there's the rub. Since my benzoate is sodium too, I'll have to pick up some Kbenzoate. It'll be worth it if I can get a nice green whistle rocket (or, dare I hope, blue )

Thanks for the clue!