Torn Lawence wrote:
The British made some WWII engines with rotating cylinder sleeves that
had in and out ports cut into them - rotary valves! No poppets. Good
performance, but burned oil and left conspicuous smoke trails, not a
good thing for a warbird to do.

That's what I remember from an engine class, unless I'm hallucinating
again.

That was a sleeve valve engine, Harry Ricardo's magnum opus. The
Bristol Hercules and Centaurus. Wear was an issue they never did tackle.

Charles