First Whistle Rocket

[mabuse00]

Perhaps you can give me some hints.

 

http://www.pyrobin.com/files/1_3.avi

http://www.pyrobin.com/files/2.avi

 

I used 70/30 Fuel (Potassium benzoate) with 2,5g vaseline + 1% Cu oxychloride.

Motor dimensions are 100mm x 15mm id, my spindle resembles the pusher proposal from the RTS. 50mm long, 9,5mm at the base, 3mm on top.

Increment was about 1/3 - 1/2 id (compressed).

28g fuel. Sticks where to short.

 

Second used iron oxide but i blew the tube due to improper sleeving. I fixed the cut with cardbord and fired it anyway, just for the fun. Of course it blew right after take off.

 

 

I want more trust. Is there any way to get more burn rate? Some people use 76/23 fuel, I may try that next.

But I've also got a feeling that the rough "rattling" burning somehow slows it down...? What do you think about the pusher design, is it much more critical the "standart" type design with the shorter spindle, besides higher pressure?

[dagabu]

Mabuse,

 

The first rocket was great! There is nothing wrong with the raspy sound it made, such is the nature of the Copper Oxychloride catalyst.

 

There are as many spindle styles for whistle as there BP spindles, the whole thing is a matter of what you want to trade. The only way to get more thrust or excell the burn rate is to give the fuel more surface area to burn. This is accomplished by using a longer spindle. The problem is that a longer spindle usually yields CATO due to too much pressure so a slower fuel is used or only a few increments of whistle is used at the bottom and the rest is strobe, color, BP or filler.

 

The Universal tooling by Steve LaDuke is a perfect example of tooling made to handle experimenting with fuel loads.

[Zmuro]

if you used pusher tooling that rocket should take of like a bullet. The main reason for a slow start of your rocket, I would blame the particle size of your chemicals, especially benzoate and also the ratio of chemicals. You should use 76/23/1 + 2,5. Whistle mix shouldn't have any white spots in it and it must be mixed thoroughly.

[dagabu]

Here, here!

 

A blade type coffee grinder, a blender or ball mill will reduce them all to powder (each one separately) and use a wet mix to cut down on friction. Granulate for ease of loading and to keep the dust down.

[WonderBoy]

That is a nice rocket with a nice raspy sound.

I agree with what has been said, I generally use 76-23-1-2.5 KClO4-NaBenz-Fe2O3-mineral oil. Although, the mix spec'd by Eric H. for use with this tooling is 72.5-27.5 Na or KBenz, no binder or catalyst,My link and in a PF post he claimed that any more oxidizer slows down the mix. I do not know if that is true.

My thinking is that using the extra KClO4 helps balance the fuel when using the added binder.

This is only my theory though.

Edited March 17, 2011 by WonderBoy

[ExplosiveCoek]

He uses a red gum solution, so there is a binder in there !

[Mumbles]

He uses red gum for binding whistle designed for breaking crossettes and small shells. He uses straight whistle (as far as I can tell from that link) for the rockets.

[mabuse00]

if you used pusher tooling that rocket should take of like a bullet

That's what I wanted a pusher for, and that's what I hoped whould happen

The benzoate was very fine, nice dusty airfloat stuff, so the Perchlorate, and I mixed it a very long time... defenitely no white spots or lumps.

I used paint thinner, riced the stuff and let it dry until it didn't stink any more.

 

I'll try more oxidizer. I can't use a much longer spindle, because the tubes are only 100mm. 70mm instead of the 50mm I used will be the maximum.

I only used 50mm because I was afraid the tubes would not cope with the pressure, but they seem to have more potential.

 

Machining a spindle is quite annoying, because i don't have acces to a lathe. Fortunately i've found a 16mm chuck a my parents place. So i started with angle grinder, rasp and sandpaper.

[Mumbles]

I think you've found your problem there. You can't expect it to work if you drastically change the dimensions. Your spindle is 30% shorter than recommended. It should be about 75mm long, so hopefully 70, and just taking out a bit of the empty space will do the trick. IE keep the spindle dimensions the same, just remove a bit of the cavity the tooling forms.

[mabuse00]

I think you've found your problem there. You can't expect it to work if you drastically change the dimensions. Your spindle is 30% shorter than recommended. It should be about 75mm long, so hopefully 70

No. You misunderstood me.

If you check out the RTS, it proposes a 3.33 x Id spindle for a pusher, =>50mm.

75mm whould be more like a "long winded screamer" type.

 

and just taking out a bit of the empty space will do the trick. IE keep the spindle dimensions the same, just remove a bit of the cavity the tooling forms.

What do you mean, take away some of the fuel grain?

I thought about extending the core with a drillbit...

 

 

I'll do some more tests as soon as I have time for it.

[dagabu]

I think Mum is talking about you only pressing whistle up to the point just below it CATOing and load the rest with delay, color, tame BP etc.

[Mumbles]

You may want to look at the original documentation, it may be more useful than a recreation of it. Notably, the empty cavity formed by the tooling should be the same all the time. I have no idea what effect that may have on performance.

 

Anyway, we were talking about two different things. You (presumably) were talking about the core forming portion of the tooling itself. I was talking about the entire piece that goes inside of the tube. 50mm for the core forming portion sounds right, while the 75mm I mentioned is the entire tooling.

 

http://www.wichitabuggywhip.com/fireworks/rockets/erich/index.html

[mabuse00]

@Mumbles:

You mean to shorten spindle collar -> shorten the empty space at the beginning of the tube right?

 

I'll try. Adding some spacer over the collar is no big deal.

[Mumbles]

Well, I originally thought the entire spindle was 50mm. It sounds like you made it to the correct size. Someone else would be able to tell you if the empty space in the tube would affect thrust, or just tone.

[dagabu]

According to my notes with Duke, it was 1-2 diameters open tube for the sounding chamber. RTS has 1.5 which seems to be right in the middle.