The Simplest Steam Engine

[RimstarOrg] has posted an awesome writeup on his Hero’s steam engine . Hero’s engine is a Greek design from the first century and is the earliest known steam engine. It’s amazing to think he developed the engine seventeen centuries before the industrial revolution, and yet it was largely ignored. While you can find more faithful replicas, of this landmark machine [RimstarOrg]’s rig can’t be beaten for simplicity and he does a great job of explaining the principal of operation and construction.

Using a soda can filled with water and a propane torch [RimstarOrg] was able to get the can to rotate rapidly by ejecting steam from two holes in the side of the can. A fishing swivel is used to provide a pivoting joint and allow the can to rotate freely.

While we’ve covered steam engines before, we loved this simple design, and can’t wait to see what [RimStarOrg] comes up with next.

20 thoughts on “The Simplest Steam Engine

    1. I can see how you might suspect that but if the jet of the torch was what was spinning it then it wouldn’t take around 30 seconds before it starts spinning. That time requirement is consistent for whenever I start it up with a fresh load of water (i.e. cool water.) I also did a follow-up one here where I used a homemade alcohol stove, one without the torch’s jet and it worked as well.

    1. Ion engines don’t produce enough thrust to overcome the breaking torque of a load on the generator, such as the batteries it is charging, or magnetron it’s driving. It’d be like trying to start an 18-wheeler in 15th gear.

        1. The mass isn’t the issue. As soon as a load is connected to the generator a magnetic ‘friction’ is created between the stator and rotor. Ion engines produce ~100 mN. Even a modest magnetron would provide more than sufficient load to counter the thrust of an ion engine.
          If some sort of ‘skip fire’ style generator were made, the duty cycle would be so far in towards the spin-up portion that it would be impractical. The fly wheel on such a mechanism is probably beyond current materials. The centripetal force across it’s diameter would likely approach the tensile strength of the best of modern materials.

          Never mind where we’re getting power to power the ion engine. They’re really efficient for specific impulse, but not as generators. Certainly less efficient than just hooking a magnetron directly to a space based PV array.

  1. this is more of a steam turbine that a steam engine. steam engines produce power by condensing water vapor and creating a vacuum in the engine cylinder. this device does not condense anything, just shoots steam out of a couple nozzles (holes).

    also, steam is an invisible gas. you can only see the water vapor after is cools enough and begins to condense. next time you’re making tea, look at the nozzle on the teapot. the plume of water vapor starts 1/2″-1″ from the nozzle where it has had enough time to cool and condense.

    1. Ehh? Steam engines don’t condense into water and create a a vacuum in the cylinder – it enters under high pressure and undergoes adiabatic expansion, thus moving the piston..

      1. Yeah they do, well condenser ones anyway as [Adrian Johnstone] says.

        Basic principle is the piston is at the top, the cylinder is full of hot steam. Spray in some cold water, the steam vanishes (condenses) in a instant, the difference in air pressure inside & outside the cylinder forces the piston down. (That’s the Newcomen design.)

        James Watt built one that worked really well.

    2. Umm, I think what you are describing is an atmospheric engine such as the Newcomen engine, or its close relative the Watt engine (which uses an external condenser). These kinds of steam engines were made obsolete by Tervithick-style high pressure engines in which the expansive property of high pressure steam is used to transmit a force to a piston.

    1. That’s a good idea for a liquid that’s doesn’t fizz when shaken (sorry, I don’t know the technical terminology.) It’s hard to tell from the video since I didn’t show it all, but the can empties in around 10 seconds if shaken the whole time so no need for the second hole yet.

      1. Certainly easier than opening the ring pull then trying to reseal it after.
        Perhaps in order to fill it again either a syringe or if done gently, heating then submerging in cold water (allowing the change in temperature and therfore presure to draw in the water. (gently as not to crush the can).

    1. “Well, Hero, nice little spinning thing you have there. To what useful purpose can it be put?” “I haven’t figured that out yet.” “Pish! forget it then! Come up with something useful.”

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