Learn How A Radial Engine Works Or Gawk At Amazing Wood Model

[Ian Jimmerson] has constructed a detailed model of a radial engine out of wood and MDF for an undisclosed reason. Rather than just delivering the wooden engine to wherever wood engines go, [Ian] decided to take the time to film himself disassembling and reassembling his engine, explaining in detail how it works as he goes. He starts by teaching about the cylinder numbering and the different possible cylinder configurations. It only gets better after that, and it’s worth watching the full 20 minutes of video. You’ll leave with a definite understanding of how radial engines work, and maybe build something neat with the knowledge.

Our only complaint is the lack of build photos or construction techniques. It’s a real feat to build something with this many moving parts that can run off an electric drill. Was a CNC involved, or was he one of those hardcore guys who manage to get precision parts with manual methods? Part 1 and 2 after the break.

19 thoughts on “Learn How A Radial Engine Works Or Gawk At Amazing Wood Model

  1. Very nice. At one point I was marginally involved with an overhaul of a The Pratt & Whitney R-4360 Wasp Major, a large 28-cylinder supercharged air-cooled four-row radial piston aircraft engine. A very impressive unit.

  2. That was the coolest thing I’ve seen in a LONG time… I was mesmerized on the second vid when he attached the drill to the back and let it run. I’ve rebuilt standard inline and V piston engines and know how they work, but have always wondered how a radial worked. Thanks for this article.

    1. Agreed!

      The electronics geek in me says – put some RGB LED’s where the spark plug would be and colour coordinate the suck-squish-bang-pitooey strokes. (off – yellow – white flash/red – dim white, or maybe green)

  3. How to make it cooler? Put an RGB LED inside each cylinder and some sensors on the rocker arms. Add a micro of your choice + code to have it vary the LED colors to match the cycles. Blue for intake. For compression have it brighten through the compression stroke then quickly go to bright orange then fades to red through the power stroke. Finish off with a light red for the exhaust stroke. Start over.

  4. Amazing, I think I even have some idea how a radial engine works now, this guy would have been handy in WWI (or II) but it’s nice to see his work, or should I say artistry today.

    1. Interesting link, thanks for sharing it. I’ve seen other engines of that type. I think they were referred to as “rotary” engines back in the day, this being many years before “rotary” would typically mean “Wankel”.

      1. They had a good power-to-weight ratio for their day up to a certain size, but suffered from other problems as well including lubrication issues, and severe gyroscopic effects as they scaled. But for a time many manufacturers were offering them.

      2. A “rotary” engine can also refer to a thing that looks like a radial engine as pictured here, but where the entire crankcase rotates with the propeller, and the cylinders are fixed to an offset pin attached to the non-rotating base. The Gnome rotary is the most famous of these:


        It’s a crazy-looking design from today’s standpoint, but I suspect the mechanics were a lot simpler to work out. Flying behind one of those would have been a very practical lesson in gyroscopic precession.

  5. That was an impressive model radial engine and excellent description of it’s operation! I’d understood many of the pieces, but this pulled them all together.

    Umm… Maybe not all of them. I’d always wondered how such engines are lubricated. In automotive engines, the oil is pumped into bearings, and allowed to drip through the crankcase back into the oil pan (sump) where it is pumped out to the bearings.Radial engines have no oil sump, but plenty of bearing surfaces that need oil. Oil would collect inside the bottom piston and cylinder.

    How is the oil managed?

    1. They use a dry-sump design with an external oil tank, scavenge pump in the centre of the crankcase, and a pressure pump with hoses to everywhere else, or in earlier designs they had fresh oil supplied from a tank and discharged it out the exhaust. Yes oil collects in the bottom cylinders when the engine is off and this had to be addressed in the starting procedures.

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