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Adding charcoal to rocket fuel

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#1 Uarbor



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Posted 22 June 2022 - 08:08 AM

I am currently using my ball milled Willow black powder as fuel for my core burner Rockets made on universal tooling. They are definitely on the red line. I want to add some charcoal for spark effect and to slightly tone it down. What size charcoal do people add for this purpose I have 36 mesh 80 mesh and airfloat. I tried the 36 it did not seem to slow it down much but boy did it make a nice tail. I'm just wondering when people say add charcoal do they mean airfloat?

#2 justvisiting



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Posted 23 June 2022 - 12:10 AM

I'm assuming you mean nozzled rockets. If you add airfloat, most of it is consumed in the rocket, and it does slow the burn rate by changing the formula. If you add coarse charcoal like -36 or -80 mesh, most of it is consumed in the off-board reaction outside the motor (sparks).  'They' say that adding coarse charcoal slows the propellant down, but that's not actually true. The burn time is actually shorter because there is less propellant to burn when coarse charcoal is added. I tested this on the Acme to prove that point. In the end, the result is probably about the same as far as backing away from the red line goes, whichever way you go. 


I don't know if you have standard BP tooling or not, but it does give you a lot more versatility than the weaker universal tooling. There are so many combinations you can use with either kind of tooling. With the universal tooling, you can mix your sparky, weak BP propellant with some whistle and get good power with a nice tail- without a nozzle of course :)

#3 Arthur



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Posted 23 June 2022 - 02:37 PM

BP burns approximately completely, BP with extra fine charcoal burns more slowly and supposedly burns to CO (rather than CO2) leading to smaller molecules supposedly exiting the nozzle faster. 


If you check in Lancaster's book he has lots of formulae using various cuts of BP with more or less extra fuel to make rockets of all sizes, gerbes, fountains, wheel drivers etc. 

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