Black Powder Rockets
When I started my pyrotechnic hobby I didn't think too much about rockets. Rocketry was a different pursuit and I wanted to concentrate on learning to build mines and shells. After a couple of years I realized that black powder rockets had more of a place in this hobby. There are numerous types of rockets and different payloads they can lift. Once I had watched Tom Rebenklau's video on crossette headings, I was hooked. The first step was to get a good set of tooling. This is tooling for one pound rockets that I got from Wolter Pyro Tools. There are several places you can find rocket tooling, but Rich's quality is great and his prices are more than fair.
The casing for a one pound rocket is ¾ inch ID, 1½ inch OD, and 7½ inches long. I make my fuel rather hot, so as with anything else, this is only a starting point for experimentation. Carefully record your own tests and when you find something that works, stick with it. For my fuel I use 75% homemade meal BP and 25% charcoal at 36 mesh. The black powder I use is ball milled 74-14-12 using commercial air float charcoal. Then I just mix in the 36 mesh charcoal which slows the fuel to the point it won't CATO and also gives the rocket a nice tail. I press these rockets without a reinforcing sleeve, but you have to be careful not to damage the tube. I've found that pressing to 800psi on the guage of my press works fine. You can build a basic press, but I bought one from Hobby Fireworks. This picture shows the nozzle being pressed (2 teaspoons of bentonite clay). One advantage of not using a sleeve is you can see just when the tube begins to bulge, which locks in the clay.
The rocket is finished with a 1½ teaspoon clay bulkhead. Removing the motor from the spindle can be difficult. I clamp mine in a vise then use a strap wrench to break it free. After it's removed, I use my drill press to hand drill a hole through the clay just until the fuel is reached. Now it's time for the header. With the fuel I use, these rockets will easily lift a 3 inch shell. A 5 by 32 inch strip of 70# kraft is wrapped 4 turns around a 2½ inch former. Insert a fused chipboard disk, pleat the paper down over it then glue on another disk. The fuse in this case is just a piece of visco about 1½ inches long with just enough on the inside to reach the burst. One turn of kraft around a 5/8 inch former is hot glued over the internal fuse. Now the shell is inverted and filled with ½ inch stars and cushioned with pulverone. Be sure the case is tightly packed. The burst core is filled with 3FA black powder and a solid disk placed on top. The remaining paper is pleated down and another solid disk glued over it. I also use masking tape to secure the end disks while the glue dries.
All that's left is to spike the shell. I use 6 strand flax twine from PyroSupplies.com. I use 12 verticals and space the horizontals at about 3/8 inch. I use a few more verticals than a regular 3 inch shell since I don't bother to paste it in. This is also why I use 4 initial turns of paper instead of 3. The resulting burst is very nice. After spiking I apply a liberal amount of hot glue around the fuse and surrounding string as a fire barrier in case of blow through from the hole in the bulkhead. Then I attach the shell to the motor with more hot glue. Once everything's dry the rocket is taped to a 36 inch long 3/8 inch square dowel. For a fuse I insert a piece of visco all the way up the core. The curve in the fuse holds it in place nicely. When launched from a well secured tube, this rocket reaches respectable heights and gives a very nice display at its peak.