Sorry Tim, that went over my head. Easier to understand the Atkinson cycle for my brain! (Call me stupid - most people do!).
Ken & all, Good chatting with you in 2020 - I've actually had a good year - I have missed a lot of things with the Pandemic, but just the selfish "Modern Human things". No-one I know has died - though hospitalised - and (maybe the Seasonal feeling?) there is hope for 2021 being better!
Don't be glum - HAVE FUN! - However and whoever you can share it with.
As a child of the 1950s in the UK I have seen worse than 2020... - the family poverty etc. - but we didn't know we were poor (by today's standards) so if we could be so happy then, there is NOTHING stopping us being happy now. I know (now) that we were underfed as children, because that's all we could afford. We had hand-me-down clothes, (that was real re-cycling!) walked - as there was no cash for buses - dug veg from the garden, etc.
And there were talks of the A-Bomb, end-of-the world with the H-Bomb, Russians invading Czechoslovakia, Hungary, and shipping missiles to Cuba... Air-raid practices, bomb-sites from WW2 as a reminder of history, and the occasional car accident killed someone (so few cars!). A smallpox outbreak (1962 I think?) Polio scares, we had measles, mumps, chicken pox and all, Ice on windows in the morning and choked on the fumes from the paraffin heater - we couldn't afford coal - but an hour of paraffin warmed us before we went to bed. And we'd "never had it so good!".
So Covid pandemic is just another brief chapter of life. Write it in the History books and move on - to the next model!
HOPING YOU ALL STAY WELL AND HAVE A HAPPY CHRISTMAS, and may all your castings be free from blow-holes in 2021!