Scratch-built Radial Solenoid Engine Is Polished And Professional

There’s something alluring about radial engines. The Wasps, the Cyclones, the Gnomes – the mechanical beauty of those classic aircraft engines can’t be denied. And even when a radial engine is powered by solenoids rather than internal combustion, it can still be a thing of beauty.

The solenoid engine proves that he has some mechanical chops. If you follow along in the videos below, you’ll see how [Tyler] progressed in his design and incorporated what he learned from the earliest breadboard stage to the nearly-complete engine. There’s an impressive amount of work here – looks like the octagonal housing was bent on a press brake, and the apparently homebrew solenoids are enclosed in copper pipe and fittings that [Tyler] took the time to bring to a fine polish. We’re skeptical that the microswitches that electrically commutate the engine will hold up to as many cycles are they’d need to handle for this to be a useful engine, but that’s hardly the point here. This one is all about the learning, and we think [Tyler] has done a bang-up job with that.

For more radial solenoid engine goodness, check out this engine with an entirely different take on commutation. Or if you need the basics of radial engine theory, this wood mockup might be just the thing.

23 thoughts on “Scratch-built Radial Solenoid Engine Is Polished And Professional

  1. I love these – and though I realize that a conventional electric motor wins hands-down in the efficiency (and parts count) department, is there any niche where a solenoid engine works better? Low end torque perhaps?

    Also, if you want a brain-exploding mechanism, look into the Bristol Hercules sleeve-valve engine’s operation ( ) and remember – the original was designed on paper.

    1. Niche-wise, this is really just an exploded stepper motor, more or less, so probably isn’t really more useful than any real motor. Still cool to get working though.

  2. Alternating linear motion is the worst because you need to accelerate and decelerate a mass twice for every cycle.
    Acceleration cost energy and deceleration don’t bring it back
    Vibrations are also a price to paid.
    Rotation is written everywhere in Maxwell equations, why deny it ?
    This said, beautiful hack

    1. The recipricating mass attached to a crank is a wash, the energy you spend accelerating the mass is given back to you on the decelerating (minus the friction of the sliding and the bearings).

    2. Not so… During deceleration the kinetic energy of the piston is transferred either to the kinetic energy energy of the shaft or one of the other pistons or work done at the output. A frictionless piston engine would spin forever.

  3. Very nicely done! Excellent solenoid engine build, keep up the good work!

    That being said, I find myself wondering if a single hall-effect sensor and a microcontroller couldn’t handle the commutation duties, along with replacing the switches with power MOSFETs. Might be more reliable, easier to balance, have less friction, and certainly would be simpler mechanically. Just a thought…

    1. I was thinking the same thing. I was also thinking that you could wind opposite-side coils together to eliminate a switch… one side pulls while the other pushes, then vice-versa on the other side. Electronic commutation makes this sort of thing much easier!

    2. you would have very little less friction as the only friction you are saving is what the cam and micro switches develop all of the other friction would still be developed the best thing he could do is fit ball bearing races to each end of the main shaft supporting it at both the front and rear of the cranks also fit oil light bearings to each of the solenoid connecting rods, also a quick spray with a Teflon based lubricant to the solenoid shafts would help a lot I use to work with lots of solenoids and any time there was any trouble with them a quick spray would fix them 95% of the time.

      Regards Poppy Ann.

  4. Where the shaft goes through the plate at the top of the motor, I would like to suggest using a ball bearing–a 608ZZ bearing. It is inexpensive and available everywhere; try Adafruit or eBay.

  5. should have avoided the losses of pivot linkages, and all the extra associated parts required.4 radial scotch yokes would have been much smoother. Still pretty cool though

      1. So you’re saying that scotch yokes have less friction than pivot bearings? I find this highly unlikely since the distance the moving parts slide against each other in each revolution are so much higher. But never mind my opinion; look how quickly this motor comes to a stop when you turn off the power, even with that huge flywheel on it. Yeah, it’s smooth, but keep in mind that friction has a damping effect.

  6. I don’t know how the solenoids in the copper pipe look like, but if they are like the ones in the second video then there’s a simple improvement that could be made: by enclosing the solenoid in steel the reluctance would be made smaller and the same current would produce higher force. I don’t think there is any real application of this but I must say it looks beautiful.

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