In 1965 Salkeld sketched out possible configurations for air-launched manned shuttle vehicles that could be air-launched from a C-5 transport. These would have two drop tanks, but otherwise be single-stage-to-orbit designs. Payload would be a crew of two, plus three passengers, and minor additional equipment and supplies required for in-orbit repair of satellites. The basic design would be ejected out of the rear cargo door of a C-5. A more capable growth design would be carried externally on the centre pylon of a double C-5 or new-design giant transporter. These concepts were very similar to those pursued in the Soviet Union in the late 1970's. However neither NASA nor the Air Force was interested in pursuing the concept.