Simplest 2-stroke engine

[Mick BaileyParticipant @mickbailey28509]

I recall a design described in ME many years ago for a 2-stroke engine that had no compression – I suppose it may be referred to as an atmospheric engine. I can’t remember if it featured an inlet valve, or what the exhaust arrangement was. It’s probably quite inefficient but would make an interesting model as it may be a straightforward build as an open crank design. Does anyone have more information?

[Michael GilliganParticipant @michaelgilligan61133]

I must confess, Mick … I am bewildered by the very concept of a 2 stroke engine without compression.

I did, however, attempt a search … and stumbled across this series which might possibly trigger some memories:

http://www.modelenginenews.org/etw/2s/index.html

… I shall be reading it later.

MichaelG.

.

Edit: __ this may be the clue

The early “atmospheric” internal combustion engines, such as the Hugon and Lenoir, were two-scokes, in the sense that combustion took place once par complete revolution of the shaft, i.e., two strokes of the piston. But these engines were completely superseded by the Otto engine, in which the mixture charge was compressed …

[JasonBModerator @jasonb]

Not sure of the actual article but quite possibly about the French System Loyal or our Southalls Patent, I know Westbury wrote a bit about them. Both of which were ways that were tried to bypass the Otto patent

Designs are about for the Model Engineer who wants to make one. Engineer’s Emporium have the “pioneer” and Poly have their “AGE” (atmospheric gas engine). There is also a barstock design about possibly by Phil Duclos. Over in the states several of Nick Roland’s engines use his “modified Loyal Cycle” such as the Type B which I have made

Hardy and Padmore who had the Southall Patend made quite a nice little engine the “Ideal” which I have drawn up at 4/10th scale and done the CAD work for. I’m just waiting for one of the castings to arrive then that will get built up. In the mean time Graham Corry has got the other set of castings built up and running. Bit of a gerry-rigged job at the moment as it is prooving difficult to get it to run with a small enough hot tube to look scale so a larger set of castings are being made. This is it on hot tube, note the ball bearing and hacksaw blade currently being used which mimic the hinged flap that H&P used on the exhaust valve that used gravity to close it. Soft spring on the atmospheric inlet for both types but loyal had a spring to close the exhaust

Also works with a spark plug, both using propane.

And if I get my finger out and finish the drawings then a replica of the loyal engine shown bottom right may appear

[JasonBModerator @jasonb]

A couple more of Nick Rowland engines. I’ve been pestering him for drawings of the new design for some time.

[Mick BaileyParticipant @mickbailey28509]

The ETW article is exactly where I read about the engine. I was clearly  mistaken in thinking that it had no compression – more correctly, it has no incoming charge compression, effective compression being performed within the cylinder. Maybe what distorted my memory was the valves being atmospheric.

As someone used to steam and hot air engine builds it’s quite an  appealing departure into the world of IC engines.

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