M2F2, HL10, HL20, X23, X24A, X24B Lifting bodies set

In 1957, NASA had investigated the problems associated with re-entry from space of missile nose cone. Engineers conceived the lifting body idea that by modifying a cone shape, aerodynamic lift could be produced to fly back from space rather than plunge to the earth. This study led to the design known as the M-2, a "M"odified half-cone, rounded on bottom and flat on top, with twin tail-fins. This configuration allowed lifting body to be landing on a runway rather than parachuting into the ocean. In 1962, NASA built the first lifting prototype, the unpowered M2-F1. With the success of M2-F1 program, NASA signed contract to Northrop to build the rocket engined M2-F2 and HL-10. In 1963, USAF joined the program. Martin was contracted to build the X-23 test-bed and the piloted X-24A. In 1972, the X-24A was modified to X-24B with shape in delta platform to validate the Space Shuttle landing concept. In 1990, the lifting body program was revived with the HL-20 PLS (Personal Launch System). It is a reentry vehicle that was designed to complement the Space Shuttle orbiter.