The Hypersonic Spin

On the 15th of November 1967; Michael J Adams' took the seventh X-15 flight, in the number three aircraft. At 10:30 in the morning, the X-15-3 dropped away from underneath the wing of Balls 8 NB-52B mothership at 45,000 ft over Delamar Dry Lake.



Three minutes later, Adams reached a peak altitude of 266,000 ft. In the NASA 1 control room, mission controller Pete Knight monitored the mission with a team of engineers.

As the X-15 climbed, Adams began a planned wing-rocking maneuver so an on-board camera could scan the horizon. 40 seconds later, when the aircraft had reached its maximum altitude, the X-15 was tracking off heading by 15 degrees to the left. As Adams came over the top, the drift halted as the aircraft's nose yawed 15 degrees back to the correct attitude.

As the X-15 traversed into a descent, the drift reappeared; within 30 seconds, Adams' descending flight path was at right angles to the attitude of the aircraft. At 230,000 ft, while descending into the rapidly increasing density of the atmosphere, the X-15 entered a spin at 5 times the speed of sound. Mach 5.0



Adams radioed that the aircraft " seemed squirrelly," and moments later repeatedly told Knight that he had entered a spin. The ground controllers could offer little to get the rocket plane straightened out... there was no known spin recovery technique for the X-15, and engineers knew nothing about the aircraft's supersonic spin tendencies. The chase pilots, realizing that the X-15 would never make Rogers Dry Lake, headed for the emergency lakes, Ballarat and Cuddeback, in case Adams attempted an emergency landing.



Adams fought the X-15's controls against the spin, simultaneously using flight controls and the reaction control jets in the nose and wings. Amazingly Adams' managed to recover from the spin at an altitude of 118,000 feet, then went into an inverted Mach 4.7 dive at an angle of 45 degrees.

At that point, the X-15 went into a limit-cycle with rapid pitching motion of increasing severity, still in a dive at 160,000 feet per minute. As the X-15 neared 65,000 ft, it was diving at Mach 3.93 and experiencing more than 15 g vertically, and 8g laterally.

Adams' X-15 disintegrated in mid flight northeast of the town of Johannesburg 10 minutes and 35 seconds after launch. Test Pilot Michael J Adams was killed as his aircraft broke apart.

 

The United States Air Force posthumously awarded  Test Pilot Michael J Adams Astronaut Wings for his last flight...

 

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