Mark wrote:Or for a simple short run "rocket/pulsejet", (disposable), maybe make your V-2 shaped rocket out of paper, but lined with the shells from light weight aerosol cans to protect the walls from burnout. Then let her rev up and lift off straight up into the wild blue yonder for a few seconds of burn time.
It would cost hardly anything, all the materials to make a short running pulsejet could be made out of garbage. A pulsating combustion "rocket" would be a lot more fun than those store-bought bottle rockets and they could be very light in weight.
That's almost exactly what I wanted to do with the Dynajet years ago, but of course I never did because I had no clue how to make a reliable recovery system that would give me back my engine unharmed. With a junk jet that would run well on a lightweight butane refill cylinder, you wouldn't care, as long as it didn't fall on anything of value. As you say, the vehicle itself would need to be little more than a paper shell with aluminum foil lining and some stabilizing fins.
Tailpipes can be the "curtain rod" from a piece of Sauder u-build-it furniture: 1-inch OD, tightly seamed, paper-thin chromed steel tube, perfectly round. I had no trouble welding such a tube into the top of a (too large) pressure can to make Long Tall Sally. The end of the tube fits so tightly, you probably wouldn't even need to weld it for a one-time shot, just have enough 1/16-inch wire bracing to keep it lined up in the rocket body. With one of the miniature cans (like hobby enamel comes in), your engine could be put together simply and cheaply. There would be virtually no slosh in the butane cylinder, because of constant acceleration (ha!) during the burn.
An ideal demonstration of the "jets from junk" philosophy.
Of course, actually firing such a vehicle would be utterly irresponsible ;-)