Скачать или смотреть Rocket motor test [failure​]. KNO3+Sugar propellant (520 g or propellant).

During weekend was my first launch of the DIY rocket. Actually, this was not the rocket - this was just the rocket motor with glued to it fins. Also, I'd made electric matches and launched the rocket using the long wire.

The motor was made from cardboard tube (I took it from cling wrap, external diameter - 40mm, internal - about 36mm). The channel in propellant (molten sugar + KNO3) was 8mm in diameter. All this was glued with epoxy (top stub). The nozzle was also made from epoxy (diameter of the nozzle was also 8mm). The stub and the nozzle were heavy and additionally, I drilled some holes to increase adhesion. The weight of propellant - 520g. The total weight of motor - about 600g.

It took off up to 20 meters and then burned and had fallen down into 2 burning pieces. I had found the quite whole top stub. I had not found the nozzle. The cardboard tube burned out almost totally.

Please, guide me, what have I done wrong? I suppose, that the problem is in the cardboard tube:
1) Maybe, cardboard tubes from cling wrap are flammable and better to make cardboard tube by myself using paper and glue?
2) Maybe, cardboard tubes are bad for such amount of propellant and need to use aluminum tubes?
3) Maybe, the problem is somewhere else?


P.P.S. I had understood, that better to launch the rockets somewhere very-very far from trees. I had the fire extinguisher in my car, but fortunately, he did not come in handy.