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my model rockets dont seem to work all they do is smoke i made the fuel correctly but what am i doing wrong???

I make them with 20 grams potassium nitrate and 11 grams sugar but they don't work when I compact it in the pvc.

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Kiteman8 years ago
  • It may be damp (sugar and nitrates both absorb water from the air).
  • Is the fuel ground fine enough?
  • Have you constructed a nozzle?
  • It will burn faster if you compact the fuel around a mandrel - put a thin smooth dowel down the centre of the pipe and pack the fuel around it, then slide the dowel out of the rocket to leave a "tunnel" through the fuel that will increase the surface area that burns - more fuel burns, so it burns faster, producing gas faster.
(We can give more helpful answers if you include images of your problem - what does your rocket actually look like? Maybe even a video of the failed burn?)
lemonie8 years ago
PVC is a bad material for a rocket motor - you need to wrap tubes from paper. L
Actually PVC makes great rocket motors. I have been using it for years. They are even environmentally friendly as you can use them over and over.
in the sixties, a friend and i made a rocket out of a Srripe toothpaste tube ( without the toothpaste obviously), which flew quite well. Being old and senile, I can't recall how high it went.
I guess it depends upon the fuel, but PVC is more dense than paper / card (usually) - heavier. Fuels I was thinking of would burn it, but I'm probably thinking of something different. L
I have used rocket candy (sugar + KNO3) and black powder fuels. For most model rockets the short amount of time for the burn does not melt the PVC and the ability to reuse the tube vs. weight difference makes up for the small difference in weight. Plus the PVC is stronger than the paper tubes.
I was thinking of the chlorate mixtures I've used, which aren't the same (still working on something that gets off the ground...) L
Chlorates are very dangerous and not recommended for use in model rocketry nor in making fireworks. Chlorate fuels have spontaneously ignited on their own. Good way to seriously injure someone or destroy your home or garage. Please be very careful. You can make model rockets that do not violate FAA or other federal laws, but will soar to great heights with safer fuels like rocket candy and black powder.
Yes, I know this from experience... L