Forty Years ago in the X-15 Flight Test Program, November 1960 - January 1961
Scott Crossfield concluded the North American contractor demonstration of the X-15-2 with the XLR-99 engine on December 6, 1960. He was launched from the NB-52A by Major Jack Allavie and Major Frank Cole over Rosamond Dry Lake on the southwest side of Edwards Air Force Base.
The mission plan called for the XLR-99 engine to burn for 121 seconds, pushing the X-15-2 to Mach 2.30. The rocket engine burned for 128.9 seconds, and Crossfield exceeded the planned speed by over a half of a Mach number, reaching Mach 2.85 (1,881 miles per hour).
Mission 2-12-23* was Scott Crossfield's last rocket powered flight. He had made his first rocket powered flight in the Bell X-1 nearly ten years earlier, on April 20, 1951.
Sometime after the first flight of the big engine in early November 1960, the NB-52B acquired nose art in the form of an eagle dropping an X-15 set against a blue circle. The eagle carried a ribbon in its beak and the name under the eagle read "The Challenger". The upper part of the blue circle was clipped by the lower edge of the DayGlo orange extending aft from the top of the chin radome. Note that the lettering and badge are outlined in bare metal against the DayGlo orange. Similar markings were applied directly over the DayGlo orange on the NB-52A. The mission mark just to the left of the lower deck window represents mission 1-15-28, which was flown on October 28, 1960. Photo courtesy AFFTC/HO.
Following Neil Armstrong's first flight in the X-15-1 on November 30, the "barber pole" air data boom on its nose was removed and replaced with the Q-ball (pronounced cue-ball). Q stands for dynamic pressure. The Q-ball nose was machined out of solid Inconel-X. It detected the direction from which the airstream was striking the nose of the X-15, and its construction would allow it to withstand the high temperatures that would be generated at speeds above Mach-6.
Mission 1-19-32, the first flight of the X-15-1 equipped with the Q-ball nose, was scheduled for December 8 with Neil Armstrong at the controls. The flight was postponed by weather until the following day. Armstrong was launched from the NB-52B by Major Allavie and Major Cole over Palmdale. The primary objective of the flight was to evaluate the function of the new air data sensor, so Armstrong's top speed was only Mach 1.80 (1,188 miles per hour) and his maximum altitude was only 50,095 feet.
The NB-52B with the X-15-1. The barber pole air data boom has been replaced with the Q-ball nose. The Day-Glo orange has been stripped from the the engine nacelles and the undersides of the wings of the NB-52B. The bare metal area formerly covered by orange paint is slightly brighter. The earliest flight that this picture could have been taken on is mission 1-19-32, flown on December 9, 1960. The last flight that this picture could have been taken on is mission 1-21-36, the last flight flown with the XLR-11 engines on February 7, 1961. Photo courtesy AFFTC/HO.
Major Robert White was scheduled for a flight in the X-15-1 on December 15, but a hydraulic leak postponed his flight. The X-15-1 was taken out of service for ten days in December while wiring associated with its inertial navigation system was installed.
John McKay's second X-15 flight was initially scheduled for January 11, 1961, but it was postponed until January 31. Then it was postponed for another day by a hydraulic fluid heater failure. Major Fitzhugh Fulton and Major Ken Lewis launched McKay from the NB-52B over Palmdale on February 1. He reached a top speed of Mach 1.88 (1,212 miles per hour) and a maximum altitude of 49,780 feet.
The NB-52A was flown to the Boeing plant in Wichita, Kansas in January 1961 for periodic maintenance. Only the NB-52B was available to launch the X-15s until the NB-52A's return in April.
Angle of Attack : Harrison Storms and the Race to the Moon by Mike Gray. The biography of Harrison Storms, who was instrumental in the development and operation of the X-15.
At the Edge of Space : The X-15 Flight Program by Milton O. Thompson. The story of test flying the X-15 from the point of view of the pilot.
*The first position of the mission number identifies which X-15 was involved, the second number indicates how many times that X-15 had been launched, and the third number indicates how many times it had been carried by an NB-52.
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