Part of the Charles A. Lindbergh Lecture at the National Air and Space Museum, Smithsonian Institution by lifting-body pilot Bill Dana.
With the end of hostilities at the close of World War II, the United States finally had the resources to focus on ways to fly higher and faster. One of the tools in this assault of speed and altitude was the rocket airplane, and observers saw the arrival of the X-1 and its breaking of the sound barrier in 1947(X-1 Slide)
. The X-2 flew to Mach 3(X-2 Slide)
, and the X-15 to over Mach 6(X-15 Slide)
By the time the X-15 was rolled out in 1958, the Air Force was already studying the next step in "higher and faster". . . an airplane that would perform a lifting entry from near orbital speeds. This was the X-20(X-20 Slide)
, which was conceived in the late 1950s. It started out as a suborbital research airplane and was escalated, conceptually, to an orbital, operational vehicle.
It eventually was canceled before construction of it was started, as the Air Force geared up to fight the Vietnam War.
While the X-20 was still alive, it represented a lifting entry orbital spacecraft for the Air Force at a time when NASA did not have one. But an enterprising young NASA research engineer at the Dryden Flight Research center at Edwards came across a wind-tunnel developed lifting entry shape designed M2(M-2 Slide)
, which had been designed at the NASA Ames Research center. The shape was a lifting
fuselage, with no wings, developed to use the aerodynamic forces of reentry to maneuver to a suitable landing area, and then to land horizontally on a conventional runway. The M2 was one of many lifting body shapes investigated by NASA in its wind tunnels, and a forward-looking Ames Research center scientist named Al Eggers developed it.(Al Eggers Slide.)
Eggers completed his design before any object,
including Sputnik had ever launched into Earth orbit. I have long used the M2 as an example of how far ahead of flight the advanced designers work.
All the proposed lifting-body shapes of that era exhibited gentle curves. At the time of the development of the lifting bodies, ablative coating was the state-of-the-art thermal protection, and spacecraft of that time needed gentle curves to maintain gradual thermal gradients.