It Isn’t Rocket Science — Wait, Maybe It Is

We don’t know why, but for some reason, the more dangerous something is, the more hacker appeal it seems to have. We like to deal with high temperatures, high voltages, dangerous chemicals, and powerful lasers. So [Tech Ingredient’s] recent video about homemade rocket motors certainly caught our attention. You may need a little commitment, though. The first video (yes, there isn’t just one) is over an hour long.

Turns out, [Tech] doesn’t actually want to use the rockets for propulsion. He needed a source of highly-ionized high-velocity plasma to try to get more power from his magnetohydrodynamic project. Whatever you want to use it for, these are serious-sized motors. [Tech] claims that his design is both powerful and easy to build. He also has a “secret” rocket fuel that he shares. What is it? We won’t spoil the video for you, but it is a sweet surprise.

The video isn’t just a how-to. There is a lot of discussion about how rocket motors work, which isn’t as intuitive as you might think. Of course, when you build rockets, weight is everything. There’s generous use of epoxy to provide strong barriers and seals without a lot of weight. If you just want to see the pyrotechnics, you can start with the second video — a smaller investment at less than 12 minutes.

The largest motor was roughly an H-class motor, which is very powerful. A top-end commercially available model rocket engine is usually an F-class and each letter is double the amount of thrust, so these are serious size motors.

If you want a better look at what happens inside a motor, try building this one. Surprisingly, you can even 3D print a liquid engine.

22 thoughts on “It Isn’t Rocket Science — Wait, Maybe It Is

      1. I don’t know, RCS is cold and I think it classes as a rocket.
        I’m now imagining F-RCS on a space suit for manoeuvring, but it might be hard to get it pointed the right way.
        That said, not lighting it is definitely a missed opportunity for more thrust. The nozzle might be uncomfortable though…

        1. As long as the liquid cooling system doesn’t fail and anneal the nozzle… or worse go full ablative mode. Careful about the chamber pressure too or you might have an aerospike with engine rich exhaust.

  1. This is illegal in the UK if anyone was thinking of doing it over here. Can’t manufacture solid rocket motors. If you want to build rocket motors here then hybrid or micro-hybrids are your options, using a liquid/gaseous oxidiser.

  2. Tech Ingredient’s video is nice. But when he says “simple DIY rockets” and just after says that you will need a nozzle made out of graphite and doing the nozzle in the lathe….then its not that simple. Graphite is not that cheap and not everyone has a lathe.

    1. The other day I watched an old Time Team re-run where they were digging up an island that iron age people had made jewelry on.

      They performed a demo of what had gone on however long ago. They made a lathe that was basically some chunks of tree and a sapling tied down with a rope to form a bow providing the turning action. They made a beautiful bracelet out of rock that looked like as good as if it had been turned on any modern piece of factory equipment.

      Perhaps a better question than “does everyone have a lathe” is “does everyone have an imagination”.

      Where there is a will there is a lathe.

      1. Pole lathe, you can make it modern version with bungee cord, but i don’t know if it would be ok for graphite turning. Bodgers use it to turn wood, i’ve seen amber and other soft materials like copper done by reenactors.

          1. High self lubricity too, you’d have a hard time snagging in it and stalling even a weak motor. So you could rig it up with your $20, 900 rpm, hand drill and have at it with a sharpened spoon.

    2. It’s a long video. I haven’t seen how big a piece of graphite you need yet but searching Amazon for “graphite block” it doesn’t look prohibitively expensive. Unless I am vastly underestimating the size.

    3. I machine graphite for rocket nozzles, and believe me, it’s something to be avoided if possible. A good dust collection system is absolutely necessary. Graphite will short out a lathe motor in jig time, and it gets EVERYwhere. You’ll blow your nose black for at least a day or two.

      It is referred to as “compressed filth” for good reasons. :-)

    4. you don’t need graphite nozzle, for simplier rockets with black powder or sorbitol/sugar mixtures you can just use cardboard infused with superglue, it will do ok for that one flight and you don’t need to worry about falling objects. Then you can use other materials like clay (make sure its dry, then bake it with hand torch you should be able to go above 600deg C and thats enough to burn out chemically bonded water and mot care abut clay having steam explosion)

      1. Agreed. Literally hundreds of millions of rockets, both skyrockets and hobby rocket motors, have been made with clay nozzles. Ordinary cat litter works (preferably unused ;-)) for blackpowder and for sorbitol/sugar mixtures. In fact, some Estes rocket motors appear to have used that for their nozzles. For greater strength add grog—ground-up fired clay—or kyanite.

        A clay nozzle that has been rammed dry will break apart into dust if the motor overpressurizes. No falling-object hazards.

        FWIW erythritol has been used by some amateurs I know. It has a somewhat higher melting point than sorbitol (120C vs. 98C) but its tendency to absorb moisture is much less than that of sorbitol.

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