Rockets using a mixture of powdered zinc and sulfur as a fuel. Ignited with cannon fuse.
We recently had our first successes with this fuel, it's quite powerful and easy to mix. However we're in the process of trying to use ethanol casting to get a more uniform fill, which should reduce the likelihood of explosions.
We've also been working on the shapes of our rockets and what materials to use. We had a pretty good launch with a copper tube rocket, but that's expensive so we're trying out PVC at the moment. (less info)