How engineers used a B-52 to rapidly advance our understanding of supersonic flight

NB-52A-0003, takes off with an X-15 mounted under the right wing.
The Challenge: The engineers have designed and developed a new aircraft that can fly five times the speed of sound (Mach 5), but it does not carry enough fuel to take off from a runway and climb to its operational altitude.
The Answer: launch it from another aircraft—the “mother ship”—that will carry it to its operational altitude so it can begin the flight from there. This article outlines a brief history of two B-52 aircraft that would support the X-15 program, one of which would continue in the role as a “mother ship” for another 35 years.

NB-52A Preparing for an X-15 flight early in the program.
While the B-52 was not the first “mother ship” (a modified B-29 Superfortress bomber was used to launch the Bell X-1 and Chuck Yeager on the first supersonic flight in 1947), this is a brief history of two B-52s that defined and lived the role for nearly fifty years.
By the time the North American X-15 hypersonic test aircraft was ready for testing, the B-52 Stratofortress was available, and two B-52s were transferred to Edwards AFB to act as mother ships for the X-15.
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