I'm building these motors from a combination of directions from WikiHow and the King of Random... for fuel, I'm using Potassium Nitrate (KNO3) and Sugar, in a ratio of 2:1 by mass. The casing is built of glued construction paper and capped with bentonite clay. Simply put, my issue is that my motor does not develop enough power to lift itself off the ground. Data from Experiments with high explosives in large guns, by Sir Hiram Maxim (available on JSTOR) indicates that the burn rate of gunpowder (and thus, I assume, solid rocket fuel) is dependent solely upon the granular size of the oxidizer. Microscopic examination of my rocket fuel does indeed indicate that each grain of KNO3 is 4 or 5 times the size as any given grain of powdered sugar. The KNO3 was bought online as an aquarium supply, and so the grain is also not perfectly uniform. Attempts to lower the grain size with a mortar and pestle and a small blender (an "Ibico Portable USB Rechargeable Handheld Blender") made no discernible difference to the grain of the nitrate. Does anybody have any ideas on how I can increase the power of my rocket motors for a reasonably low price (I can't afford the $30-40 for a larger blender right now, so let's set that as the price cap)?

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    $\begingroup$ Making your own rocket motors is a rather hazardous undertaking and I'm not at all sure it's on topic for this Stack. $\endgroup$
    – Zeiss Ikon
    Jul 25, 2023 at 16:05
  • $\begingroup$ I agree. Chances are high that you can't afford to safely make (even low-power) rocket motors if your price cap for safety and equipment is ~$30. I strongly recommend purchasing motors from vendors like Estes or AeroTech/Cesaroni and getting high-power rocketry certifications before trying this. It's immeasurably more fun to experiment with rockets when you still have all your limbs. $\endgroup$
    – ifconfig
    Jul 26, 2023 at 6:24
  • $\begingroup$ I'm kinda surprised we don't yet have a rocketry forum on the network... but then again the community is fairly small :shrug: $\endgroup$
    – ifconfig
    Jul 26, 2023 at 6:26
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    $\begingroup$ @ifconfig We do have a Space Exploration site, but questions about personal/amateur projects and/or building engines/making propellants are explicitly off-topic/disallowed due to the dangers inherent in those activities (like you and Zeiss Ikon mention). Sorry for the late ping $\endgroup$ Mar 19 at 23:39


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