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Pneumatic rotary engine: R-66

by VincentGroenhuis Aug 27, 2018
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I love this project, great job!

Nice to hear! Are you 3D printing a R-66 motor too?

Finally somebody who knows what a genuine rotary engine is! Thank you!

As a mechanic and engineer, I get so incredibly tired of people calling Rotary Piston (Wankel) engines Rotaries.

Hey, it should be possible to design and 3D print a functional Wankel engine! With no valves and a double symmetric design? Who knows...

I would adore to see such a thing. In concept, it's not even difficult, just a matter of keeping your tolerances tight without being so tight they can't be 3D printed. A Wankel, in a lot of ways, is basically just a vane motor, so I can't imagine it'd be much harder than that. Hell, I'd be willing to bet you could just modify one of the existing Wankel models out here on the 'Verse for a super basic proof of concept.

I might just give this a shot when I have more time on my hands. You could probably do it better, though, if your work on this motor is any testament to your ability. A very impressive piece.

There is a animation about the pneumatic Wankel concept: https://www.youtube.com/watch?v=zuZy_eAnwXo
The hardest part would be to properly seal off the top and bottom gaps. A 0.1 mm high, 30 mm long gap is already a highway for air molecules. Putting a large rubber seal around the entire perimeter would cause too much friction, I am afraid. Food for thought...

Nice design.
But that is a radial engine, not a Rotary engine.

Thanks! Do you realize that the crankshaft is stationary and the cylinders are rotating?
Based on the Wikipedia information and animation on https://en.wikipedia.org/wiki/Rotary_engine#/media/File:Rotary_engine_-_animation_slower.gif the R-66 is a rotary engine I think. So I'm interested in how you would classify a radial or rotary engine, could you explain? Thanks!

That is quiet interesting.
I think you are right, I thought rotary engine are the same as wankel engines.

To correct:
Your engine is a rotary AND a radial engine :)


Still, the Wiki's rotary engine link makes a distinction between rotary and radial based on whether the cylinders are rotating or not. Theoretically my engine could be adapted to make the crankshaft rotating and the cylinders still if the inlet pneumatic tube is allowed to rotate indefinitely around its axis. Or use it as a stepper motor, with external valves. In both cases it is indeed a radial engine (or sort of).