(Henry Spencer) writes:

In article ,
Richard Lamb wrote:
A C Clarke described a nover air lock in RAMA.
A rotating cylinder within a stationary cylinder.
The stationary cylinder has openings 180 apart.
The rotating cylinder only has one opening.

Unfortunately, that huge area of sliding contact (which has to have very
tight clearances to avoid significant leakage) is just asking for the
thing to seize up one day. It would take some very fancy materials
engineering to make something like that reliable.

There was a lot of effort put into intake and exhaust valves for auto
engines that worked on that principle in the early part of the last
century (no valve float, higher max RPM, more power) with exactly the
results Henry points to.
--
Joseph J. Pfeiffer, Jr., Ph.D. Phone -- (505) 646-1605
Department of Computer Science FAX -- (505) 646-1002
New Mexico State University http://www.cs.nmsu.edu/~pfeiffer
Southwestern NM Regional Science and Engr Fair: http://www.nmsu.edu/~scifair