Today is
Sunday,
March 26th
2017

Black Powder Rockets

Rocket Tooling
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.
Hydraulic Press
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. Shell Header

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. Finished Rocket

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.