The lifting body program was one of the highlight of the NASA in the 60’s. In the 1960s, Lockheed and the U.S. Air Force’s Flight Dynamics Laboratory (FDL) explored several design concepts for hypersonic flight.
source.image: Hazegrayart
Three principal vehicles, the FDL-5, FDL-6 and FDL-7, were based on 70-degree triangles and had different designs. The FDL-5 had variable-geometry wings for controlled landings, and one proposal called for it to be carried aloft by a C-5 Galaxy transport and then released at high altitude.
Some believe that the FDL-5 actually flew in 1969. If so, this makes the FDL-5 America’s first reusable spacecraft! The Air Force Rocket Propulsion Laboratory also outlined an “Air Force Sortie Space System” that had three major parts.
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A launch platform, drop tanks, and a space vehicle, which was a 747 with liquid oxygen and liquid hydrogen storage tanks inside its fuselage and hydrogen pumped into afterburners for thrust augmentation. Another option involved a vehicle sized to fit inside the shuttle bay.
