The success of Dryden's M2-F1 program led to NASA's development and construction of two heavyweight lifting bodies based on studies at NASA's Ames and Langley research centers-the M2-F2 and the HL-10, both built by the Northrop Corporation.
By then, the same B-52 used to air launch the famed X-15 rocket research aircraft was modified to also carry the lifting bodies.