This is a model of unknown scale of the X-20 Dyna-soar (Dynamic Soaring), the prototype for a single-piloted spaceplane. Originally conceived by German aerospace design Eugen Saenger as a skip-glide rocket bomber with intercontinental range, the concept was transformed by the U.S. Air Force into a manned reconnaissance platform in space. Designed to be launched by rocket into orbit, the X-20 was a "lifting body" design and would have landed like an airplane. The Dyna Soar program was cancelled in December 1963, before the first manned test flight that was scheduled for the following year. This model was built and donated by Boeing to NASM in 1990.