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I want to put an action figure in orbit but I need to know how to make a secure yet not too expensive rocket fuel engine. The design of the engine must very primitive and not too complicated.

I've read some information about hydrazine and hydrogenperoxide but it is too dangerous to use and make at a noncommercial scale. Although I studied some chemistry in highschool, I don't have so much knowledge about this matter. So far my best bet is blackpowder based fuel engine. What do you suggest?

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3 Answers 3

Note: I'm not a modeler myself, but tested several recipes of rocket candy and read rocket modeler forum for a while.

First of all, you have to think if you will be satisfied with solid propellant or want a liquid fuel engine.

Building home-made liquid fuel rocket engine is very hard. One need to find pumps, make combustion chamber from something very heat-proof and reasonably stable chemically. Anyway, some successful reports may be found on the internetz. Note, however, that if you can choose safe liquid fuel, like kerosene or some alcohol, there is no safe oxidant for liquid-fueled rocket engine. The closest thing to safe oxidant I can imagine is nitric acid, that require work on fresh air or in specially designed room and tends to form explosives on contact with many things, like milk protein (yep!), some of which are volatile

Solid-fuel model propellants are much easier to prepare and use, there are numerous articles in the internetz about such fuels. The most common one is rocket candy, prepared from potassium nitrate and sugar. I tried it to see how it works (I didn't build any rockets), but instead of sugar I used sorbitol. Rocket candy based on sorbitol can be melted and then can be casted in any form. wiki article contains both info and links to sites with well-testes recipes by successful modelers.

Another possible option is making missile model based on some classical jet. There is quite simple pulse jet and there are some books about home-made turbine jet designs.

Anyway, I recommend to search nearby rocket modeling club and find supervisor.

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Build that is a real challenge, Thank you!, – MirlvsMaximvs Dec 13 '12 at 11:57

I think that if you want a orbit, you should ask NASA, because the biggest ever rocket homemade reached " just" 56 kilometers. For NASA space starts at 100 km. A orbit asks for multiple stages with several tons of fuel, and the lowest orbit is higher than the edge of space, so its almost impossible to send a rocket into orbit.

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I don't know how hard it would be, it might not be so hard than it appears, I mean, the only think i want is put in orbit (elliptical probably) a small mass then the only think i need is some V increment in a direction. With an arduino autopìlot rocket and an aerostatic balloon (10 km) as first stage maybe there will be possible. I haven't calculated yet. – MirlvsMaximvs Dec 3 '14 at 11:43

Ok so first of all you cant get into orbit with anything "simple"... Remember that as the altitude increases, the pressure decreases, the makeup of the atmosphere changes, temperature changes and so on.

Now on to rocket fuel, if you want to go high, I suggest sinking some time into a hybrid engine. A hybrid engine uses a solid fuel and a liquid or gaseous oxidizer. There are some good example videos on YouTube of engines that use a hollowed acrylic rod for fuel and use either nitrous oxide or straight O2 to produce a very effective, throttle-able engine. However if you just starting out, I suggest rocket candy, its a cheap, homemade solid fuel+oxidizer mixture that is great for experimenting with. You can usually use sucrose and either potassium nitrate or sodium nitrate, I suggest the sodium nitrate as it is slightly lighter, but then again I'm a perfectionist.

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