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Sky Lighter design flaw


kpknd

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I took an interest in Skylighters small 1/4" ID sugar rockets and made some of them following the design specifications. First problem, The length of the core spindle (nail) is too long and ends just short of the top of the 2" long tube, easy fix, use longer tube. Next problem, Nozzel diamater too small, the motors went ShhhBANG!!! I made sorter 1" long cores ,(1" within the fuel) and solved the problem, but was a ground test so do'nt know how it will fly. I used the fuel ratio in the instructions and the 60/40. My next experiment is to use hand mixed BP and see what happens. The Skylighter plan showes the nizzel is inset way into the tube, I wondered if that might not contribute to the "Krushnik Effect" .

 

I will try finding a larger diamater wire for a spindle for a longer core for further experiments. The idea is to come up with a process that is easy, simple, and works well and does not require a lot of equipment. I figure if the motors will turn into firecrackers the fuel will be strong enugh for motors, it is just a matter of core length and nozzel diamater ratios. I did start out originaly about 16 years ago with Sleeters 5 cent sugar rocket, but it's nice to go back to the old days once in a while just for fun. Besides, it's winter, a good time to experiment.

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  • 2 weeks later...

60/40 is not the best ratio for sugar rockets you will do better to use 13/7

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Sounds interesting, I'll give it a try. I have cured the problem by using a core 3/4" into the fuel, now it works fine with sugar and BP fuels.

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Where did you get the info that 13/7 is the 'best' ratio? And best for what? Do you know what that is in percent?
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