u-Rocket Fun

[Swede]

I've always wanted to make small fireworks, and using techniques more commonly found on larger rockets, I think I have squeezed about as much performance as possible from a really tiny package. I haven't ultimately tested its ability to lift, but I suspect it's good, as the unburdened rockets darn-near fly out of sight!

 

I started with tubes (spiral wound) from Everything Pyrotechnic, the tubes you see at the top of that page. 1/4" ID, 2" long, 5/16" OD, which makes tooling nice and easy. Here's the setup:

 

http://www.5bears.com/firew/ur01.jpg

 

This style of base with removeable nozzle/core pin allows swapping for different pin and core sizes and geometries. The base is at the top; to the right are two pins, and some brass tamps are to the left. The top of a sharpie marker is in there to show the scale.

 

http://www.5bears.com/firew/ur02.jpg

 

The two pins (one brass, one SS) are 0.093" diameter, no taper, and the longer SS pin is 0.125" with a core taper. To use this style of tooling, select the pin you want to use, and simply insert it into the base. The base is drilled through 1/4", so the pins start life as 1/4" stock.

 

http://www.5bears.com/firew/ur03.jpg

 

With the pin in place, there is a cavity in the base about 3/8" that surrounds (and supports) the bottom of the tube while ramming the nozzle mix.

 

http://www.5bears.com/firew/ur04.jpg

 

Initially I was hoping to make simple rockets that did not require a tube support, but that proved fruitless... the tubes could not withstand ramming, and packing the fuel too lightly simply resulted in instant CATO. Fuels less hot, like KNO3 + sucrose, didn't have the necessary power. So I turned a block of aluminum into a support, and made use of it.

 

http://www.5bears.com/firew/ur05.jpg

 

The support block is loosened, and installed right over the tube.

[Swede]

http://www.5bears.com/firew/ur06.jpg

 

Ready to load! I found it was easiest to execute the nozzle and the fuel in one setup, rather than taking it apart after ramming the nozzle.

 

For a rocket this small, the nozzle mix needs to be fine. The clay is not the problem, but the grog I got from skylighter was 1/2 heavy gravel. I screened those chunks out, and mixed up a batch of nozzle mix 8:4:1 clay, grog, and wax.

 

http://www.5bears.com/firew/ur07.jpg

 

It was tough to get the powders into this small tube. I found by cutting a polyethylene lab dropper, it made a great funnel.

 

http://www.5bears.com/firew/ur08.jpg

 

In goes the nozzle mix in two portions. The yellow scoop is a volumetric scoop that comes as an assorted set from Lee Precision. These are incredibly handy for this sort of repetitive task. I found the 0.7CC scoop gave me exactly the amount of nozzle I needed. MUCH easier than weighing or eyeballing. Those scoops are $8 or so, a real bargain. The nozzle is hammered into shape with the drilled tamp so as to clear the core pin.

 

http://www.5bears.com/firew/ur09.jpg

 

I did not use a press for the nozzle - it wasn't needed in this case, although it wouldn't hurt.

[Swede]

The black powder was next. Meal powder would be best, but I used a good homemade milled powder that I had already granulated into approx 3F consistency.

 

http://www.5bears.com/firew/ur10.jpg

 

In testing these little rockets, I tried alcohol precipitated BP (not enough oomph, at least my batch), milled sulphurless meal, and the milled and granulated FFFG you see here. There are so many variables that come into play - how hot is your BP, how fine, use of red gum + alcohol, etc. The published books on the subject, especially Sleeter's book, discusses in great detail the use of binders and the absolutely correct use of solvent. I wanted to keep this simple, so I decided to tamp it dry and hope for the best. Using a solvent and perhaps a binder like red gum would certainly help, and make this a more efficient (and consistent) rocket.

 

I tamped in three stages, using four 0.5CC scoops of BP. The first scoop is important and forms much of the core, although this short little pin really doesn't count as much of a core, but it does give a bit of extra "oomph" at liftoff. I guess you can call it a hybrid... starts as a core and transitions to end burning.

 

http://www.5bears.com/firew/ur11.jpg

 

Two more scoops, then tamp some more. A final scoop brought the BP level with the top of the tube. I took this over to my press and gave it four good strokes after the ram made contact with the tamp. Over-ramming caused too much tube distortion, and the tooling was difficult to remove. Under-ramming = CATO. You simply have to find what works for you. A mallet would work as well.

 

http://www.5bears.com/firew/ur12.jpg

 

The tube support is removed from the base with a twisting motion. It brings the pin with it, which is easy to remove.

 

http://www.5bears.com/firew/ur13.jpg

 

The fine clay mix makes a sweet nozzle. This taper is about 20 degrees. I have yet to have a nozzle fail... these weak spiral tubes give way long before the nozzle does.

 

http://www.5bears.com/firew/ur14.jpg

[Swede]

Payload: I am still working on what sort of header this little guy will lift. For the purposes of this tutorial, I simply placed a few grains of loose BP in the top, and jammed in some flying fish. Something to see as the motor burns out!

 

http://www.5bears.com/firew/ur15.jpg

 

I like hot glue rather than tape. With rockets this small, you need to be aware of the diameter of the visco you are using, if you want to insert the fuse into contact with the BP.

 

She's ready to fly!

 

http://www.5bears.com/firew/ur16.jpg

 

These rockets are cool, especially if you are in a suburban (or urban) setting. Even a CATO is not especially loud. When they do fly, it is relatively quietly.

 

With no payload, these little guys will damn near fly out of sight, probably because they are too small to see! There's lots of room for further experimentation. As I mentioned in another thread, I want to see if I can make some really small fireworks behave like their larger cousins. In other words, rather than using this rocket to launch 2 or 3 small stars, or a baby salute, I am going to mess around with attempts to make many SMALLER stars. This is just the beginning, a mechanism to get them airborne.

 

Best of all, they're just a lot of fun; quick, easy to make, inexpensive, and discrete.

[pyrogeorge]

very nice tutorial!keep going the good work!

[jacob]

I second that, nice tooling, do you have any details on your tube support? I want one like that for 1lb rockets, hose clamps and a PVC tube work but it's quite slow.

[ST1DinOH]

this is a great tutorial BTW...nice clear pics and a great idea.

 

nice work.

 

got me thinking that something like this would be perfect for making a small scale girandola and doing some mass launches with them.

 

currently over at pyro u there's a lot of guys talking about using the "reloadable" girandola kits, and just making up a peg board (using the appropriate sized wooden dowels) to send up a massive front of them.

 

some of the cases come packed 36 to a case...you can imagine having a wall of 36 mini girandolas all take flight in unison would be nice...but i'd wager these little guys would make a far more impressive girandola...especially when topped off with a little 70/30

[MilkyJoe]

very nice!! I don't suppose you have any dimensions for the tooling do you? I would love to get a set made up. =D

 

Also, do you have any videos?

[Swede]

Thanks guys. I can make a simple print of the tooling if desired, but the pics are pretty self-explanatory.

 

The tube support wasn't too tough. Two blocks of aluminum are used. One is drilled and tapped, the other is match drilled through for 4 socket head cap screws. There are two ways to make the hole, which needs to be centered perfectly on the seam. One is to simply drill it with the two blocks secured together. There is a trick to ensure the drill does not wander... You simply scribe a line on the inside surface of both blocks where the center axis of the hole is to be, and by hand, with a round needle file, file out a tiny channel on both blocks. It doesn't have to be deep at all, nor does it have to be all that even. Secure the blocks together, and do a preliminary drilling with a small drill, letting the filed channel guide the drill. There is a natural tendency for the drill to follow the seam, but even a minute filed channel will amplify the effect. Once the preliminary hole is drilled, you then follow up with a drill that is the same OD as the tube.

 

The other way to make the hole is to drill it straightaway on a very good drill press or mill after center punching the seam, being sure everything is aligned well.

 

Of course you could go with any of the normal rocket tube support methods like split PVC, etc. There's much less overall force on this little rocket than there would be on a normal, larger one.

[KinneticEnergy]

I would kill for a print(Not literally of course )!!!!

 

I myself am deeply interested in the making of miniature pyrotechnics. Why waste so much bp on larger ones? And plus, cool effects, like ti, look so much cooler coming from such a tiny device. I've been attempting to build 1/8" id rockets, with a dragon egg as a header, with moderate success. Those mini-girandolas someone was talking about would be cool... If anybody ever comes up with plans for a 1/2" ball shell, throw me a pm!!!! The possibilities are endless

[nick2354]

Nice, Could we see a video?

 

OT: Also in one of the pictures, I see you thumbnail has black powder in it.

I can safely say your not the only one.

[Swede]

I'll try to get a video tonite - I'm not sure how much there'll be to see. I have no capability to edit video, so if it works, it'll be a pretty low-grade clip from my older camera.

[hst45]

Swede, excellent work! I too enjoy the small-scale devices. I now have a pretty large launch area so I'm making some bigger stuff, but for years I worked on backyard displays, and I find the challenges of making a good small-scale rocket/shell/ etc such as yours very rewarding, and you're FAR exceeded what I was able to do. Great job with the tooling.

[TheSidewinder]

Very nice tutorial, Swede!

[FrankRizzo]

I've got the little bottle rocket kit that Wolter sells, which uses those same 1/4" ID tubes or you can use the longer NEPT tubes. I must've rammed ~2-3 dozen of 'em last winter to get my pyro fix. They are fun little rockets and can even carry a small payload of a few 1/4" stars or a 1/2" comet if your BP is hot enough. I've heard you can even make mini strobe rockets though I haven't tried that yet.

 

Another use for your tooling is for making spoolettes.

[Swede]

Well, I must have tried a dozen times to get a decent movie. All I've got is the same Sony still camera that I used here. It does allow small video clips, but I have no editing capability.

 

Tiny FF Header

 

I think I have the basic motor done. The next step is a separate header with a proper delay, and some sort of micro-bursting charge with perhaps some more falling leaves to start. And I do agree, a miniature girandola would be very cool, very challenging too!

 

I tried another core pin, much longer and more in-line with theoretical motors, but they all blew up - too much pressure. I'm sure with good, hot BP, a plain end-burner would work well.

 

I'm going to try something similar with 2 ounce (3/8" ID) tubes as well. These tiny rockets are fun, and I think there's a lot of potential for micro-fireworks.

[Swede]

I'm having a blast with these. Today, I made a batch of very hot willow BP and rammed a half-dozen quickies with the meal powder right out of the jar. The performance gain (and lack of CATO) was impressive vs. the granulated powder.

 

The problem with the granulated was that essentially I was re-compressing it back into meal, and if not done 100%, the air voids and larger BP chunks cause catastrophic pressure spikes that blow the whole thing. The meal powder is messier and harder to load, but so far it is behaving much better, and the burn is significantly longer because I'm able to jam more fuel in there.

 

The meal powder also allows a much longer core pin, resulting in more thrust and a better burn.

[WarezWally]

Very nice tutorial

 

I love bottle rockets, nobody cares if you shoot a few off every now and then seeing as they don't make any noise and no cop is going to break out the nightstick over a handful of bottle rockets.

[MilkyJoe]

you should attempt a mini girandola using these bottle rockets as drivers... should be interesting

[Mumbles]

Something about the size of a plastic tin of chewing tobacco should be just about right.

[Jason]

Just to add, those little 1" ball shells you can buy from cannonfuse or a similar store make good headers for these little guys.

[psyco_1322]

You could convince all your friends when the 4th comes around to dump all there dragon eggs from the green balls into one big container and use them as little shells. They get more effect and you get casing, great deal! I made a few small shells with them, they were a light and throw shell though. Just drop in a few stars, a pinch of whistle or slow flash and a a piece of visco and tape with fiberglass re-enforced tape worked great.

[_DB_]

Nice tutorial! I love smaller rockets.

 

I doubt he still comes here, but _Po_ used to make some awesome small rockets. Last I heard he was forced to completely quit pyrotechnics.

[moonshot]

My god! You must be an Engineer! That tooling is strong enough to make tiny nuclear missiles I have rammed bottle rockets this size without using any reinforcing sleeve with excellent results, and agree that these rockets are really fun to fly. I,m thinking of pressing them with whistle mix and adding a 1 or 2 gram fl*sh header to make an uber

Whistling bottle rocket. Rocket on!

[PyroCanada]

Swede, im sure that the dimensions and print of those tools would be much appreciated and respected by many of us (especially me)