I was reading an article in Invention & Technology on the navy's steam driven catapults and got to wondering how they sealed the slot in the cylinder. Google turned up lots of pages but nothing on sealing. I'm envisioning that the piston/traveler pulls a ribbon off a spool(like a tape measure) which seals as it goes. but this has got to be a reliability and maintenance nightmare. Anybody know how do they do it?
Art