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Sarge
I really can't say...
Mon Aug 7, 2017 16:03
2601:982:8200:5f50:8c16:3fbe:f27e:7cff

...regarding the rotary as a two stroke, because I am not all that conversant in two stroke engines, other than knowing they can be atmospherically sensitive, which is not a good thing regarding an aero engine. There has to be some limitation inherent, else they would have garnered some notice in that field somewhere in the world. At the moment I don't know whatit is other than the guess I just now tossed out.

The only two-cycle aero engine I can remember off the top of my head is the Junkers opposed piston diesel (might be the only diesel aero engine that I can remember), which is what Fairbanks Morse copied (without license) as their locomotive and marine plant.

My experience with two stroke engines is pretty limited. I drove three-cylinder Saab 96 rallye cars. It was a bit air density sensitive, needing a little fussing with between winter and summer and a noticeable performance change climbing into mountain ranges. That probably is what has me wonder if that would be the limitation as an aero engine.

There has to be something, or there would have been more serious work in those days when these guys grasped for every pound of weightsaving because of the limited lift capacity in the designs of the first quarter of the 20th century.

Emissions killed off two-cycle auto engines, at least for Saab, but there has to be something else in this application, a horsepower limit, air density, something. I don't know enough, so perhaps time to dig around and find out.

Why weren't two-cycle engines common in aero design?

  • Not at all - mike, Mon Aug 7 12:08
    Quite the reverse! I've been keeping a tight rein on my personal preference for technical detail and discussion. BTW I think you misread that first part of the new story. I am emphatically not... more
    • I really can't say... - Sarge, Mon Aug 7 16:03
      • Theres a definite bias - mike, Mon Aug 7 19:33
        Amongst engineers against two strokes and its largely based on a chimera, thats to say the experiences from the past when technology wasnt up to the task. Since they do twice the work they have half... more
        • That being the case... - Sarge, Tue Aug 8 06:59
          "I love them" ...you should stick with that as a story element. However... I raise the question from a grave suspicion there must be a reason why, with all the advantages of weight and power output,... more
          • Steambird - mike, Tue Aug 8 09:53
            I have that book too. I know some British inventor did fit a steam engine into an airframe tethered to a short stretch of rail which developed enough lift to break free - if memory serves? Sir George ... more
            • For bikes and cars... - Sarge, Tue Aug 8 11:38
              ...I'm with you on two stroke being viable, and in some cases advantageous. Can't have rallyed a Saab 96 without marveling. I well remember the two vs four schools in bikes, though I understood my... more
              • Well that just makes things better - mike, Tue Aug 8 14:15
                Do you know that I hadn't considered those aspects of the changes in atmosphere that you spoke about? Should have done though but I simply dismissed it as a problem similar to that of changing... more
                • That's probably wise, BUT... - Sarge, Tue Aug 8 15:59
                  ...you might not give up on the debate as a good character development tool. I suspect Colin, being the automobile fan, is a four cycle guy, and might hold user prejudices to that predilection. Then... more
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