My elder brother developed a childhood interest in rocketry, until he discovered that rocket engines with crimped nozzles are grenades, and blew up a neighbor's back porch. The sacrificial blow-out nib on the fire jar is sort of intriguing from a rocketry point of view. The blow-out feature is reminiscent of the DuPont gunpowder factory in Delaware. the factory buildings had 3 stone walls and one wooden wall, facing the river. When the inevitable explosions occurred, the wooden wall blew out and deposited the debris in the river. The DuPonts could then simply replace the blowout wall, roof, (and employees) and get back to work. Very practical folks. It is hard to believe that we have been talking about explosions for 2 days without a comment from Blast. Anyway, nice kit, nice concept,Raven-