-I was out of touch and/or out of the country from 1990 to 1998. We didn't even have reliable e-mail and the internet we know today didn't exist. When I got back to CONUS I reestablished contact with a guy who was an honest to goodness rocket scientist, a physicist. One of the projects he was working on, unclassified, was similar to what mvdmitri posted but with an interesting twist: instead of metal many of the engine components were to be made of ceramic. Evidently this was to minimize the expansion/contraction properties of metal. As i recall the concept the platform wasn't going to be powered 24 hours/day; maybe that meant flying on one engine vice two.
-Never heard anything more on the topic. I thought the bit about ceramic component engines was neat.