The experimental rocket plane blazed a trail for the space program.">
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In This Issue
From the Academy Director: Change Management and Adaptive Challenges
The Knowledge Notebook: What's Right About Being Wrong
Interview with Wayne Hale
Case Study: Making Compliance Comprehensible
Peer Assist: Learning Before Doing
The Impact of Energy on Projects
NASA Knowledge Forum 2: Knowledge in Projects
NASA + SpaceX Work Together
The Freedom to Learn
X-15: Pushing the Envelope
From Sketch Pad to Launchpad: Shaping the Shuttle
A Carrier Team One Risk Management Success Story
MIDAS: Keys to Software Success
The view from the cockpit of the B-52 carrier aircraft. (Click image for close-up) Photo Credit: NASABreaking the sound barrier took guts, curiosity, optimism, and some serious risk taking. Equipped with slide rules and other fifties technology, the army, navy, and North American Aviation teamed up with the National Advisory Committee for Aeronautics (NACA) to create an aircraft that could outfly all others. Through a series of experimental aircraft, NACA—later NASA—pursued supersonic and hypersonic flight with record-breaking results. The lessons learned during this ambitious research program contributed to many other NASA programs.
The X-15 mockup as it was inspected in December 1956. (Click image for close-up) Photo Credit: U.S. Air Force
Scott Crossfield sits in a thermal-vacuum chamber during tests of a prototype XMC-2 pressure suit. Production versions of this suit were used for thirty-six early X-15 flights. (Click image for close-up) Photo Credit: BoeingTo solve the yaw problem, the team developed a wedge-shaped tail: narrow at the front and wide at the back. This helped keep the air streams apart longer at hypersonic speeds, which gave the plane exceptional directional stability. The wedge tail is now a commonly accepted shape for hypersonic control surfaces, but the X-15 was the first to employ it on a manned aircraft.
Above: The X-15 research aircraft during its first powered flight on Sept. 17, 1959.
(Click image for close-up) Photo Credit: NASA
Joe Engle during the X-15 program. (Click image for close-up) Photo Credit: NASAEach flight lasted about eight to ten minutes. Around eighty seconds after the X-15 was launched from under the wing of a B-52, pilots would shut down the engines. The rest of the flight was unpowered, and the pilot was essentially guiding a highspeed glider. Precision piloting was critical. If the engine was cut one second too late, or if the pitch was off by one degree, pilots could end up thousands of miles off track. With the only navigation available being line of sight from the X-15's two small windows, a few ground stations, and non-hypersonic chase planes, overshooting the course meant emergency landing decisions had to be made and communicated quickly. And if one of the windows glazed or cracked from the heat of flight—a problem that often occurred—pilots were reduced to tracking on only one side of the plane. This made the stopwatch in the cockpit very important for accurate energy management and flight-path positioning.
A HEART-POUNDING EXPERIENCE
A major concern when NASA began to explore human spaceflight further was the physiological responses of those chosen to fly the missions. Heart rates for pilots were very high, and data from X-15 pilots directly influenced the decision to fly men into space. Below is Walter C. Williams' account of how the heart-rate issue was finally resolved.
We were working hard on Project Mercury. We were getting ready to fire Alan Shepard on the first ballistic flight. Prior to that, we had a little hearing before the President's Scientific Advisory Committee. It had two types of members: engineering types and aeromedical types.
We had a terrible time with the doctors; that's the only way to describe it. They thought we ought to fly seventy-five more chimps before we flew a man. I'm serious! We had the data from this one chimpanzee, which showed very high pulse rates, and they were concerned that this might kill a man or you'd pass out or what have you. And so we had quite a go-around on that.
Meanwhile, the X-15 was flying out here and the pilots were being monitored and, yes indeed, they had high pulse rates due to stress; their highest rates were usually before launch or landing. So I sent out for that data and brought it in and for a while I thought they were going to cancel the X-15 instead of clearing us to fly Project Mercury!
So Don Flickinger, the senior research aeromedical doctor, and one who had been closely following the X-15 program, got one of the doctors on the committee and Joe Walker in a three-way conversation (the data we had involved Joe Walker). The doctor began questioning Joe about this and that, then saying, "These pulse rates are pretty high—over 150. How did you feel?"
Joe responded, "Oh, I felt all right. Now wait a gosh-damn minute. Are you trying to ask me whether or not I fainted?"
The doctor said, "Well, yes. Did you faint?"
Joe replied, "Hell, no! I didn't faint!"
The doctor continued, "Well, I don't know … people can pass out and not realize it."
Joe retorted, "Look, what I did one second depended on what I had done the second before, and I'm here talking to you!"