Passing fire to a CAN or BALL Shell using a Sugar Rocket

[stix]

I'll start by stating what my aims are - that way it's probably easier to give advice.

 

My aim is to use my trusted sugar rocket motors to deliver a small shell (2.5") or a kraft paper canister shell to a height that can give something more spectacular than my star gun tests. I have tested enough 1/4" stars of the charcoal and glitter variety that I reckon I'm confident enough that it's time to move on to something bigger.

 

It may seem a small step to most on this forum (small bickies), but to me it would be a great sense of satisfaction if I can pull this off.

 

I'd rather not use bp except for the burst charge. So I'm thinking that I'll make a spolette using sugar fuel. My motors are core burners, so from ignition, the spolette/timed fuse would be burning. If the spolette has some metal in it, then a nice trail could be seen after burnout... I have Al, MgAl, and Mg turnings, I'm not sure what else would leave a nice tail on a sugar rocket, I don't have Ti.

 

I normally use a wooden plug at the header end of my motors, so I reckon I can drill a hole, then insert the spolette. I have spiral wound 1/4" tubes that can do the job.

 

Any ideas and advice greatly appreciated.

 

Cheers.

[mabuse00]

 

I normally use a wooden plug at the header end of my motors, so I reckon I can drill a hole, then insert the spolette. I have spiral wound 1/4" tubes that can do the job.

The whole assembly must be blowout proof and this is not as simple as it seems...

 

 

So I'm thinking that I'll make a spolette using sugar fuel

I would not do that.

 

First of all, sugar fuel does burn very slow, without pressure ~1-2mm/s, what makes timing very difficult. How precise can you manufacture your spolettes? +/- 1mm can make a whole second. I would rather suggest using BP, or whistle mix, the latter is more convenient to use. The faster, the more precise.

 

Also the burn rate varies very much with pressure. Now if your sugar spolette, or depending on your construction a part of the fuel grain make up the delay, delaytime will always be very uncertain.

 

BP's burn rate and thus timing precision is much less affected by pressure.

 

 

 

I have Al, MgAl, and Mg turnings, I'm not sure what else would leave a nice tail on a sugar rocket, I don't have Ti.

 

I have spiral wound 1/4" tubes that can do the job.

You would barely see the few sparks from your mini tubes in the massive smoketrail or your motors.

 

 

The best solution imho:

 

-Seal the motors top.

-Use your 1/4" tubes with BP and put them on top of your shell (test the burnrate before!).

-Pump a large glitter comet, 20mm or so, and glue it on top (Or use TT and incorperate some of your metals in it...).

-Connect spolette, motor's core and comet via quickmatch.

Edited May 2, 2015 by mabuse00

[GMetcalf]

I do rockets with shells this size all the time.

 

I do my shells in two ways depending on the size of the rocket. The first way is to finish the top of the rocket with a clay bulkhead, approximately one ID thick, then drill a hole down the side to act as a passfire. I then build the shell around the rocket (using the rocket motor in place of a spolette), putting a bunch of black match into the passfire hole to ensure ignition of the burst charge. This works alright but is better for smaller rockets which slow down faster towards the end of their fuel.

 

For larger rockets, I use a 1-2cm piece of time fuse and build the shell separately, then build the rocket the same as before but leaving a bit of space in the top of the tube, above the bulkhead (just enough for the time fuse sticking out of the shell to fit). I then fill this space and the passfire with loose black powder (usually screen mixed pulvorone) or for a bit of a pop, some flash powder, and stick the end of the time fuse from the shell in it. Then paste the completed shell on to the end of the rocket. This pops the shell off the end of the rocket and it explodes when it just about reaches its peak and at least for me, works pretty consistently.

 

I would try and provide some drawings but I'm replying off my phone... I'll see what I can do when I get home!

 

With regards to the tail, what sort of Aluminium do you have? I agree with mabuse00 that a comet might provide a better tail.

[mikeee]

Build your shell like any other shell and prime your time fuse or spolette so it easily catches fire and attach it to the top of your motor. Don't install the wooden plug and add a pinch of BP into the void on top of the motor where you attach your shell. When the motor burns up to the BP it will help ignite your shell fuse and release it from the motor. A piece of 1/4" time fuse would be easy to use for timing your shell or a standard spolette, or you could even use a piece of Visco fuse if you cut the end at an angle and prime it with an NC slurry and BP. Years ago I used cheap finger nail polish mixed with BP as a slurry on the ends of a fuse and then dip the wet fuse into dry BP this dries quickly and guarantees fire to the fuse. Most cheap finger nail polish is made of Nitro-Cellulose.

[Arthur]

My ball shells on rockets have about 1 second of delay fuse, my shells for mortar launching have 2-3 seconds according to size.

[schroedinger]

90% of my rockets are 19 and 15 mm nozzleless rockets. I press in the bp, then press in a delay of 2-4 seconds (depending on the shell used) and finish of with about 2 hot bp.

Then i take my shell after wasping and insert black match into the tube where normally the timefuse would go. The BM should sit quite snug in the tube, so it wont fall out and protude for about the same diastance as you got space in the engine.

 

Now rest the engine on the spindel (or any other device that lets you keep it straight) add hot glue to the tube and add your shell. Wait a minute for the glue to cool down and there you go. On larger shells you may need to flip the shell over after the initial goue has cooled down to apply more glue.

[enanthate]

Mix dry kno3/sugar/sodium bicarbonate.

 

https://m.youtube.com/watch?v=12fR9neVnS8

[stix]

Thanks for all the great info and ideas - there's certainly a lot to consider. A lot more complicated that I thought, but maybe I'm making it more complicated than needed.

 

I don't have commercial time fuse or visco, but have made nc coated black match which works really well, it burns around 10mm/s so I could use that as a timed fuse?. Or I could try make some quickmatch but that seems overly elaborate, but maybe necessary in the long run.

 

Once I settle on a method to pass fire, I reckon my first test will be a small 1.5 inch kraft paper can, then progress from that.

 

There's a lot to take in here, different options and methods etc. There's more questions to ask which I will do in due course. I'm not in any great hurry so I'm just fleshing out ideas at this stage.

 

Cheers.

[Oinikis]

For high-pressure sugar motors I have tried extending QM to the nozzle, and other side to the timing mechanism on top of the rocket, and igniting the motor, without igniting the QM, so QM get's ignited by the motor itself, so you would have more precise timing. You can either use fuse or a spolette on top, however, spollete might produce enough thrust to misguide your rocket, so you'd have to have some sort of deflector, or simply use a fuse.

[schroedinger]

For timing blck match won't be very reliable, specially at the momment when your shells moves through the air, use quickmatch for a passfire or build the delay into your rocket tube.

If you go for the passfire with quickmatch, use a simple spolette made from bp, glusatz or whistle for timing.

A delay that also burns reliable at about 14 s/inch is:

10 Perc

55 KNO3

10 BaSo4

12 Charcoal

10 S

5 Dammar or other Gum

Edited May 5, 2015 by schroedinger

[dagabu]

90% of my rockets are 19 and 15 mm nozzleless rockets. I press in the bp, then press in a delay of 2-4 seconds (depending on the shell used) and finish of with about 2 hot bp.

Then i take my shell after wasping and insert black match into the tube where normally the timefuse would go. The BM should sit quite snug in the tube, so it wont fall out and protude for about the same diastance as you got space in the engine.

 

Now rest the engine on the spindel (or any other device that lets you keep it straight) add hot glue to the tube and add your shell. Wait a minute for the glue to cool down and there you go. On larger shells you may need to flip the shell over after the initial goue has cooled down to apply more glue.

 

+1!

[stix]

90% of my rockets are 19 and 15 mm nozzleless rockets. I press in the bp, then press in a delay of 2-4 seconds (depending on the shell used) and finish of with about 2 hot bp.

Then i take my shell after wasping and insert black match into the tube where normally the timefuse would go. The BM should sit quite snug in the tube, so it wont fall out and protude for about the same diastance as you got space in the engine.

 

Now rest the engine on the spindel (or any other device that lets you keep it straight) add hot glue to the tube and add your shell. Wait a minute for the glue to cool down and there you go. On larger shells you may need to flip the shell over after the initial goue has cooled down to apply more glue.

 

Thanks Schroed's, My fault for not explaining properly how I make my motors and therefore how to pass fire reliably and effectively - if that is at all possible (I think it is).

 

The problem to solve, and a point to consider, is I'm not using bp. I'm using "inserted r-candy semi-bates grains". The grains have a core that go through the whole motor from nozzle to the bulkhead. I think I could use that to advantage and take fire from there. Therefore the delay mechanism has to be different than pressing a bp delay into the top as you could with what you have described.

 

As for the shell, that is secondary - I'm just trying to get to stage one, ie. passing fire with a delay. At this point I'm happy to forget about the sparkles or fancy rising comets - that will be a task for the future.

 

Cheers.

[GMetcalf]

What are you using as the bulkhead at the top? I'm thinking in this case it could be as simple as a measured piece of visco wrapped in masking tape placed at the edge of the bulkhead, hence taking fire as the propellant burns out.

[mikeee]

Stix,

 

What is the diameter of the core on your bates grains? Could you glue a 1/4" time fuse, visco fuse or spollette tube

into the last fuel grain in the motor? This would pass fire to your header or shell attachment. If the spollette on your

header or shell was the correct dimension maybe it could insert into the top grain core. You would need to calculate your

timing on the shell/header so the rocket would have time to reach the desired altitude before your time fuse/spollette

ignites the header/shell. You could also make a solid fuel grain on the top of the motor but you would need to make sure

fire does not burn around the exterior of the grain and bypass your delay. Most rockets have a delay fuel on top to start

the initiation of the timing on the ignition of the shell/header.

[stix]

Stix,

 

What is the diameter of the core on your bates grains? Could you glue a 1/4" time fuse, visco fuse or spollette tube

into the last fuel grain in the motor? This would pass fire to your header or shell attachment. If the spollette on your

header or shell was the correct dimension maybe it could insert into the top grain core. You would need to calculate your

timing on the shell/header so the rocket would have time to reach the desired altitude before your time fuse/spollette

ignites the header/shell. You could also make a solid fuel grain on the top of the motor but you would need to make sure

fire does not burn around the exterior of the grain and bypass your delay. Most rockets have a delay fuel on top to start

the initiation of the timing on the ignition of the shell/header.

 

Thanks mike, what you have described is pretty much along the lines of what I was thinking except that the time fuse would just poke ever so slightly into the top of the grain - with perhaps cross match to ensure ignition.

 

I'll post a diagram of what I think would work, and leave it open for constructive criticism. Like I said previously, I'm not fussed at this stage about having a trailing comet etc. I just want to get the basics together first.

 

Cheers.