During the late 1950s thru early 1960s a Soviet aircraft designer named Sukhanov built a series of circular research aircraft for possible military use in a modified final form. MiG had studied a circular design of their own, but there was no requirement for it, so it went nowhere. But Sukhanov continued research and then got approval for an odd disc-shaped spacecraft to be used as an emergency escape vehicle from a planned Soviet space station that never got built (Mir was another design and had no escape craft). The Sukhanov X-Tail was unique because it was bolted right onto its external fuel tank, sorta like the shuttle, only it would drop it once it got near the earth's atmosphere for re-entry. This design was built in 2/3rds scale and wind tunnel tested. It was later cancelled and the model was put into an aviation museum along with the Sukhanov 1 disc craft. It had taken many years to determine what the craft was b/c the museum people had it unlisted in their inventory and no designation nor description was displayed. Visitors were told that it was an experimental type and nothing else. But now it is known as the X-Tail and although it never got to be developed nor used, it has inspired another company to design the Russian Cosmoplan disc craft for spaceflight. All of the Sukhanovs and the Cosmoplan are below...

http://discaircraft.greyfalcon.us/picturese/disco1.jpg http://discaircraft.greyfalcon.us/picturest/disk1.jpg http://discaircraft.greyfalcon.us/picturese/disco2.jpg http://discaircraft.greyfalcon.us/picturest/disk2.jpg http://discaircraft.greyfalcon.us/picturese/disco3.jpg http://discaircraft.greyfalcon.us/picturest/disk3.jpg http://discaircraft.greyfalcon.us/picturesw/pirna.jpg http://discaircraft.greyfalcon.us/picturese/disco4.jpg http://discaircraft.greyfalcon.us/picturese/disco6.jpg http://discaircraft.greyfalcon.us/picturese/disco7.jpg http://discaircraft.greyfalcon.us/picturest/cosmoplan.jpg