rocket fuel burn rate

[baso112]

Hi there,

 

Today i have made some 60-30-10 bp rocket fuel.. i want to use it to make some rockets with my 19,7mm pyro-stuff tooling.

I want to lift 4" ball shells with those rockets but i dont really know if my fuel is too fast and if i should go for nozzled or nozzleless rockets. Greetings from the netherlands.

 

Here is the video.

 

The tubes im going to use are 20cm long.

Edited February 2, 2014 by baso112

[nater]

60-30-10 is the traditional ratio of BP ingedients for a nozzled, coreburning rocket. It is a slower comp, gives a slow lift with a distinct sound. 3"-4" ball shells are often used in that size of rocket. Unless you know the thrust of your motors, start small and dial the fuel in before lifting heavier shells.

[Mumbles]

60-30-10 is always for core burner rockets containing a nozzle. Due to the pressure inside of a rocket, I really don't have a good feel of how burn rates on the ground correspond with suitability for rockets. I guess you'll just have to try it out. Using a press will allow you to make a rocket less likely to CATO.

 

By the way, you might need to go with a much faster BP and use a nozzleless rocket to have any chance to lift a 4" shell. I doubt a standard core burner of that size could do it safely. Of course you should do lift tests before putting a live shell on there.

[baso112]

I have read somewhere cored rockets make a faster lift off when its topfused.. but i cant find anything usefull how to top fuse it.

[baso112]

So i could use the same tooling to make a nozzleless rocket with for example my regular 75-15-10 comp?

[ddewees]

I would stick with 75/15/10, it has more uses. If you want to make nozzled with cores, just add 20% airfloat charcoal. I've lifted 450g 4" shells that way with 3/4" dia (1 lb) motors.

 

Or you can just use straight 75/15/10 without a nozzle.

Edited February 2, 2014 by ddewees

[baso112]

Im going to ram them because i dont own a press.. should i make a bulkhead or can i just add some extra fuel or delay mix.

[nater]

You will need some type of delay above the spine or se your heading will display too low. Core burners get their thrust in the first 1/2 second to second of burn time depending on the burn rate of your comp. The rest of the time the rocket is just coasting to the height you want to display your heading. Delay can be any type of comp, for different tail effects. You need to dial in the burn rate of your delay to know how much to use for good timing. You might not get the best tail, but it is probably best to start using the same comp for thrust and delay. You may or may not need a clay bulkhead. This depends on how much delay is used over the spindle. Short delays will not contain the pressure of the burn and require a bulkhead to prevent the motor from blowing out the back end.

 

Yes you can use the same spindle to make nozzleless rockets with hot BP. You can also tone down hot BP as was suggested. If you want a traditional BP skyrocket, there is no substitution for a nozzled core burner with slow BP like 60-30-10.

[baso112]

I think im going for a nozzled rocket with 60-30-10 comp and i wanna nail them so i can lift 200-300 gram payloads. Tomorrow after work ill start experimenting. Should i topfuse the rockets or what is recommended?

[nater]

Some rockets need to be top fused and some don't. Top fusing a rocket is as simple as using piped match inserted to the top of the core. Bare about an inch of BM from a length of QM and insert it all the way in the motor.You might have to fold the QM in half lengthways to get it to fit. Then use whatever method you are comfortable with to light the nozzle end of the QM.

[baso112]

What is the most recommended way of fusing?

[ddewees]

J hook pushed all the way up (standard visco).

[nater]

The one that works and creates the liftoff you want. Top fusing lights the entire core at once. Lighting from the bottom with a piece of fuse J-hooked in the core lets the pressure ramp up, giving a somewhat slower take off. Sone rockets will need to be fused from the top or they won't fly. Sone rockets are so close to the red line, they will CATO if you light them from the top. Most will pribably fly either way. How will yours perform? You don't know unless you try. Which works best with your fuel and technique? You also won't know unless you try.

 

Again, start small. Start flying motors with no headings, then start adding effects in the empty space in the motor before attaching shells to the top. Most people need time to dial in BP rockets just right, especially when hand ramming them. There are a lot of variables to work out.

[Peret]

I found there's quite a difference in thrust lighting from the top as opposed to at the nozzle. Somewhere in the region of double, for my 1 pounders. It burns for a much shorter time, but has more lift power. You can top fuse just by running a bare blackmatch all the way up - the core itself acts as the quickmatch confinement. I've heard that if you're running near the redline, top fusing may CATO, but it's never happened to me.

[mkn]

Yes Nater, I had to laugh to my self. hand ramming BP rockets has a lot of variables. I am now working out the catos on my new powders made with my own pine charcoal. Prior I was using the Commercial air float from Skylighter, and had great success and consistency with my rockets and hand rolled tubes.

 

Now my fuel is much hotter, It's like starting over again, but I am lifting some good freight in tests. Seems now I must bottom light or cato is inevitable. once that is back in control, I may go back to hand rolled tubes, but for now NEPT.

 

I just tried a short ball milling 30 mins compared to 4 hours ( hoping to save time on Rocket fuel) pathetic results on bottom light, I'll try a top light and see what happens.

 

Thread is a bit old, but I had to say something when I read the " lot of variables to work out"

Matt

[nater]

I like to use commercial airfloat in rockets due to the consistency. Alter charcoal makes great rocket fuel, but I prefer to use screen mixed BP spiced up with a little whistle if it needs more snort. This makes for a fuel that is very easy to reproduce with each batch.

 

I have been all over the place with rockets. When I was ramming them, they started off barely lifting off the ground. I made some changes, and then they all CATOed. The best improvement was pressing them. I found the the fuel that CATOed when hand rammed, flies well when pressed. I am not sure if it because I worked out problems with technique with BP rockets, but I found whistle rockets much easier to dial in the first few times.

[mkn]

I'll keep that in mind on the whistle, for now I am staying away from whistle because of the need to press........ re milled the pathetic batch ( even with the mineral oil) and top light it, great take off ! hopefully I am near the point of top light or bottom light if needed and will have good lift. where my shell weights are at now, I won't be able to put a rocket that just barley has the lift needed. The weights are significantly over the next smaller rocket, I am running midrange capacity of the rocket needed. So I should be able to handle small power changes,