Granulating BP for rockets

[dangerousamateur]

Hi,

 

i just tried some small endburners with my first homemade really high quality BP. I used meal - what a mess

 

Nozzleless fuel with oil sure would help, but i want max power and cant have that, at least not in my endburner.

 

When i just wet the meal with little water and rice it - will this affect the performance?

And is there some other trick to keep the dust down a little?

[VikingPyrotechnics]

No, it does not affect the quality of your BP. I Granulate my BP always it and it works great.

Here's an example of my 1lb Endburn motors. ( 50g payload dummy on top )

 

http://www.youtube.com/watch?v=No5EhNBIVq4

 

VP

[dangerousamateur]

I like the way this thing goes up

 

How long was the fuel part and what diameter was the nozzle?

Do you granulate with dextrin or just water?

[VikingPyrotechnics]

The tube was 13 cm long. 10 grams of bentonite for the nozzle. Then pressed to the top BP.

The nozzle diameter is 4 mm. I have granulated it without dextrin.

So the granules are soft enough to be pressed tight.

[Oinikis]

---- Edited May 1, 2013 by Oinikis

[nater]

A little dextrin will help the gains store better if you don't press all your fuel right away. I have noticed fuel granulated with no binder eventually breaks back down to dust.

[dangerousamateur]

I have noticed fuel granulated with no binder eventually breaks back down to dust.

The fuel for my coreburners is always riced and does not break back to dust. As long as you don't shake it every day or something.

 

The only problem is that the riced fuel makes still some dust, and i suspect the riced ballmilled endburner fuel to dust even more. I hate working with respirator and having the black mess everywhere.

 

Seems like there is no other way

[BlastFromThePast]

Just to add, I find that 1.5% dex added to my BP for rockets makes it hard enough for storage and soft enough to ram, Definitely keeps the dust down without slowing down the burn rate appreciably. Just my 2 cents

[VikingPyrotechnics]

I still wrap a small towel around the rammer and the beginning of the tube.

Thus, the dust swirls not around, and sticking to the towel.

Maybe that solves your problem.

 

VP

[dangerousamateur]

Thanks for your advices.

 

Concerning dextrine, do you ballmill it with the BP or do you dissolve it in the water?

 

Do you care about de lavel nozzles, via tooling, or do you just drill out nozzles and short cores?

[nater]

I have tried both ball milling the dextrin into the comp and the "Dextrin Liquor" method talked about by a respected person on Passfire where the dextrin is dissolved into the water. I have taken a liking to the Dextrin Liquor method. A 10% solution of Dextrin in water is made, which is then used to granulate the comp. It seems like it dries faster. I have not tested the claims that it creates a faster burning comp than when you mill the dextrin.

 

As for the nozzle, I much prefer to use tooling than attempting to drill a core that is perfectly centered and perfectly straight. The nozzles are not a true DeLaval design though.

[BlastFromThePast]

I have yet to try the dextrin liquor as nater has mentioned. I just throw the dex into the ball mill with the BP once the BP has been going for about 2/3 it's normal ball milling time, that way the BP has had enough time to become "hot". If I add the dextrin in the beginning I find that the amount of time for the BP to be milled to it's optimal hotness increases by a little. But it's all relative.

[dangerousamateur]

The nozzles are not a true DeLaval design though.

 

Speaking about de laval, do you think pyros like us really feel the difference in performance compared to simple holes in the betonite?

 

 

 

 

And if you have a tool with 1/4 or even 1/5 diameter nozzle, do you think its possible to get your blackpowder hot enough to make them cato?

[nater]

A core burning motor with a nozzle will certainly CATO with BP that is too hot. In fact, it does not take particularly hot BP to do it. If you meant a nozzleless BP rocket, no I don't think you can make BP hot enough to make them CATO.

 

I don't know enough about rocket science to know if pyro rockets really benefit from a DeLaval nozzle design. There are pictures out there of whistle rockets with mach diamonds, but then, those are nozzleless. I think there are other attributes that make an attractive rocket which would eliminate the need for an optimized nozzle and fuel, so it is probably overkill.

[dangerousamateur]

A core burning motor with a nozzle will certainly CATO with BP that is too hot. In fact, it does not take particularly hot BP to do it. If you meant a nozzleless BP rocket, no I don't think you can make BP hot enough to make them CATO.

 

I don't know enough about rocket science to know if pyro rockets really benefit from a DeLaval nozzle design. There are pictures out there of whistle rockets with mach diamonds, but then, those are nozzleless. I think there are other attributes that make an attractive rocket which would eliminate the need for an optimized nozzle and fuel, so it is probably overkill.

 

Oh, sorry, i forgot to mention that i meant ENDBURNERS here.

[nater]

Oh, sorry, i forgot to mention that i meant ENDBURNERS here.

 

That does make a difference. I have not made enough endburners to make that call. My GUESS is that if the choke was small enough, yes you could get a CATO.

[psyco_1322]

I've had some rammed nozzleless bp rocket cato before. Then I was also using a spindle like Dan Thames used to use, which was very long and narrow, with hardly any taper. That's just asking for something bad to happen.

 

I was thinking it was Lloyd that did some nozzle tests and found out that there is better thrust to be had with the correct nozzle dimensions.

[dan999ification]

We really should have a Cato thread.

My tool gives 1/5th Id nozzle and has a longer nipple than normal, no you can't make bp too hot it will always be a failure of Something else.

The charcoal is important for a solid grain, the tubes must be up to the job, the choke or throat the right length.... The list goes on but I blame me not my bp.

I also have c/d nozzle not quite de laval but it does increase exhaust speed and performance, reduces burn through etc, it is worth it.

 

For what it's worth I also popped a few nzless bp rockets recently with 3% oil

 

Dan.

[BlastFromThePast]

Sorry for the stupid question but what kind of oil is being talked about here?

[nater]

Mineral Oil.

 

I am sure baby oil would be okay and your rockets would smell nice too.

[dangerousamateur]

Usually paraffine oil.

 

 

The reason I asked was because i was because i want to get a tool for that and i'm not sure how critical the setup can be for my needs. Commercial tools have 1/4 diameter but when you say even 1/5 is hard to cato i prefer 1/5 for more efficieny.

[dan999ification]

I was using baby oil.

 

1/5th nozzle is easy to Cato but it won't be your bp that causes it, the smaller nozzle you have the more critical everything else becomes.

 

Dan.

Edited May 2, 2013 by dan999ification

[dagabu]

Usually paraffine oil.

 

 

The reason I asked was because i was because i want to get a tool for that and i'm not sure how critical the setup can be for my needs. Commercial tools have 1/4 diameter but when you say even 1/5 is hard to cato i prefer 1/5 for more efficieny.

I was using baby oil.

 

1/5th nozzle is easy to Cato but it won't be your bp that causes it, the smaller nozzle you have the more critical everything else becomes.

 

Dan.

 

Depending on your country, they may both be the same thing. In the US, paraffin oil is kerosene. I use Naphtha or camping gas to dilute the mineral oil before dampening whistle fuel and no longer use it in black powder, I just add more charcoal to tame it down.

Edited May 2, 2013 by dagabu

[nater]

Depending on your country, they may both be the same thing. In the US, paraffin oil is kerosene. I use Naphtha or camping gas to dilute the mineral oil before dampening whistle fuel and no longer use it in black powder, I just add more charcoal to tame it down.

 

Huh, never knew that. That could make things difficult to understand depending on where you are.

[dagabu]

I am a French hand Model too.... From Wikipedia

 

Paraffin may also refer to:

Alkane

Kerosene, a fuel that is commonly known as paraffin in Britain, Southeast Asia and South Africa.

Tractor vaporising oil, a fuel

Liquid paraffin (medicinal)

Mineral oil

Petroleum jelly, also called soft paraffin