The Lockheed Star Clipper was a proposed Earth-to-orbit spaceplane based on a large lifting body spacecraft and a wrap-around drop tank.
When funding for STS development was cut, the drop tank was taken up as a way to meet the developmental budgets, leading to the semi-reusable Space Shuttle design.
[1] He later joined the Thor missile project as the chief design engineer, and this introduced him to the world of space launchers.
Several companies had already completed early feasibility studies of fully reusable spacecraft, like the Martin Marietta Astrorocket and Douglas Astro.
His suggestions caught the ear of Eugene Root, president of Lockheed Missiles and Space, who gave him the go-ahead to study what became known as the Star Clipper.
In the short term a number of different uses of surplus Saturn hardware were grouped together into the Apollo Applications Program office, rounding out missions into the mid-1970s.
Almost as an afterthought, the idea of a "logistics vehicle" developed in order to lower the cost of space station operations.
A year earlier the Air Force and NASA had collaborated on a study of existing technologies in the "Integrated Launch and Re-entry Vehicle" project, or ILRV.
Mueller dusted off the ILRV work and invited the same industry partners to present, deciding to concentrate only on the Class II designs.
General Dynamics addressed Hunters concerns about building two aircraft for one mission in their Triamese, which used several identical spacecraft grouped together with only one travelling onto orbit.
As it became clear that the program was moving forward, NASA's own teams entered the fray, adding their own designs to the mix.
In the lower atmosphere this was far too low to allow safe landings in the case of a go-around, so the Star Clipper featured small wings that rotated out of the side of the spacecraft at subsonic speeds, improving the L/D to 8.1:1.