It is amazing just how fast the X-15 program came together. The contract was awarded to North American at the end of September 1955, then, barely a year after building began on the aircraft in September 1957, the first one rolled out of the factory. Six months later, in March 1959, the X-15 made its first captive flight and, three months after that, its first glide flight. On September 17, 1959, less than four years since the project’s inception, Scott Crossfield took the most complicated and radically new aircraft design ever conceived through the paces of its first powered flight.
Armstrong was very much a part of the intense preparation: “The systems were pretty complex, a lot of things were new. The pressure came from the fact that you had to recognize what you’re going to do when the systems go wrong.”
Wind tunnel tests indicated that the X-15 at low speed possessed a very low lift-drag ratio (L/D), that is, one producing very little aerodynamic lift. Once its rocket burned itself out, the X-15 would come down fast and steep. Normal power-off landing techniques were inadequate.
Under the direction of a talented HSFS engineer by the name of Wendell H. Stillwell, flight tests involving the X-4 raised “some fairly significant concerns” for the X-15. As the unpowered F-104 “came down like a streamlined brick,” Stillwell suggested a low L/D landing program using the F-104A (and the F-102 though the plane did not have as low an L/D).
Beginning in the summer of 1958, Armstrong flew L/D approaches testing “various and sundry combinations of speed brakes and flaps” well into 1961.
Everybody involved in the X-15 program seemed to hold an opinion about the best landing approach. Scott Crossfield believed the X-15 should descend in a smooth curve as in carrier landings. Crossfield used speed brakes and a drogue chute to replicate this approach in an F-100, and to his way of thinking it worked well. Then there was the concept from Fred Drinkwater, a test pilot at NASA Ames. Based on his own low L/D studies made in a F-104, Drinkwater felt that a long, straight-in approach—one made at relatively high speed—was ideal.
Armstrong and the other NASA pilots at Edwards had issues with both approaches. Based on their own low L/D program, they proposed a third version, which they believed offered greater flexibility. According to project engineer Gene Matranga, “Our technique involved a 360-degree spiraling descent starting at about 40,000 feet” right above the desired touchdown point on the runway. From that “high key” position, the pilot moved into a 35-degree bank (usually made to the left) while maintaining an air speed of 285 to 345 miles per hour. At roughly 20,000 feet, after some 180 degrees of the spiral had been completed, the X-15 reached the “low key.” At this point, the aircraft was headed in the opposite direction of the landing runway and was about four miles abeam of the touchdown point. From the low key, the turn continued through the other 180 degrees until the X-15 lined up with the runway at about a five-mile distance. The rate of descent through the spiral averaged over two miles per minute, which meant it took on average about three minutes to go from high key to that point where the X-15 was ready to head straight in for landing.
To determine where the flare should begin, Armstrong and Walker were forced to resort to the imprecise explanation of “I feel it.” In this case Matranga understood: “We tried to work mathematical models for determining the starting point, and it just could not be done. It was just something that the pilots, with their own experience, knew intuitively, and it could, from flight to flight, vary pretty significantly.”
Scott Crossfield still preferred his way, even though his low and slow technique involved a substantially higher sink rate. In June 1959, in the X-15’s very first free flight, Crossfield’s landing was a little touchy due to a pitch damper failure and pilot-induced oscillation. In its second powered flight three months later, also flown by Crossfield, the vehicle’s nose gear door failed due to a rough landing on Rogers Dry Lake. In the following flight, in November 1959, Crossfield broke the back of the airplane when it hit hard coming down on Rosamond Dry Lake. According to the official report, the structural failure occurred on landing “due to design flaw and excessive propellant weight,” but the NASA engineers at Edwards knew otherwise. Even North American questioned Crossfield’s landing technique. According to Gene Matranga, “We had a big meeting at North American following that incident, and I can remember Larry Green, who was the company’s chief engineer on the X-15, saying, ‘Scottie, you’ve used your technique three times. You almost bought the farm on the first flight, and you almost bought the farm on the last flight. Let’s try theirs for a change.’”
North American adopted the spiral technique that Armstrong and his mates worked out in their F-104 program. The Crossfield approach was scrapped, and the technique developed by NASA became standard. In fact, the basic technique developed at the Flight Research Center worked well later in the so-called lifting body program, and it also worked well for the Space Shuttle.
Along with Matranga, Armstrong coauthored two papers on the F-104 low L/D landing investigations. The first (also coauthored by HSFS engineer Tom Finch) Neil presented at a meeting of the Institute of Aeronautical Sciences (IAS) in Los Angeles in July 1958. Dick Day, who was present at the meeting, tells the story: “Tom Finch was going to make the presentation, but they wanted the pilot there who had been through these lower L/D landings. So, Walt Williams [the head of the High-Speed Flight Station] went out and found Neil and dragged him through the back door by his ear! Literally, by his ear! It wasn’t really that Neil didn’t want to do it. I think Walt was just showing him off to the audience, ‘Here he is!’ And Neil went along with it.”
Another technical paper coauthored by Armstrong during this period involved the design of the sidearm controller for the X-15. The traditional center-stick control was difficult to position accurately under the high accelerations during rocket firing and the high decelerations of atmospheric entry. Armstrong and his mates at the Flight Research Center proposed that a small, secondary control stick be mounted on the right console, whereby the pilot could make all control movements by small wrist actions from a fully supported position. A third, left-hand control stick would operate the reaction controls. “We were not certain whether such a controller should command rotation or nose position,” Armstrong explains. “It wasn’t easy even to decide what that flight stick should look like,” and indeed it did not end up looking like the others. “We decided that the stick would pivot at the panel and then a motion up would lift the nose and a motion right would push the nose right.”
Armstrong’s systematic engineering approach again shined through: “We had worked on sidesticks for a number of years ahead of time, and what we found was quite surprising. We tried to find where the hinge points were in the wrist—and the wrist is a complex mechanism. If you picked something that seemed right to one pilot, the next pilot wouldn’t like that at all. So we took ergonomic measurements of the motions of the hand, and it turned out that the hinge points for one person won’t be the same for another. So we developed a variety of kinds of sticks and tried them in various kinds of jet aircraft. We had the opportunity to put those ideas into the X-15 during its design process so that, in fact, the sidestick turned out pretty usable. We were able to find a design that would be okay for everybody.”
Part of the sidearm controller test program took place in conjunction with Cornell Aero Lab at Cornell University in Ithaca, New York, a laboratory to which Armstrong made a few visits. Cornell had a variable-stability aircraft, a Lockheed NT-33A Shooting Star, which Armstrong flew and which the lab’s test pilot eventually took out to Edwards. In one of the test flights he flew in the T-33, Armstrong inadvertently broke off the experimental sidestick installed in the airplane.
Other technical papers coauthored by Armstrong came out of his work on the creation of the X-15’s so-called High Range. This was the supersonic flight-test instrumentation range stretching through Nevada and California through which the X-15 would be flown. Armstrong explains: “The X-15 needed several
hundred miles of space to fly the hypersonic trajectories it would fly. I was involved in the development of this high-speed range, or ‘High Range,’ and the combination of radar, communications, and telemetry that would be required to get data quickly, accurately, and in a minimum amount of time. The airplanes were a big investment, and the cost per flight was high, so it was important to be able to maximize the efficiency of getting the data.”
In one paper coauthored with NACA/NASA researcher Gerald M. Truszynski that was presented at the winter 1959 meeting of the Society of Experimental Test Pilots, Armstrong spoke about “Future Range and Flight Test Area Needs for Hypersonic and Orbital Vehicles.” With the development of more and more high-speed aircraft such as the B-58 and B-70 that could fly at Mach 2 for extended periods of time, it was important to plan to pinpoint the vast geometric space necessary to test the data. Armstrong discussed the development of the High Range (through which the X-15 had not yet been flown), but went beyond it to consider future—so-called Round Three needs—for flight test areas. (The X-1 and what followed from it had come to be called Round One; the X-15 represented Round Two. These were not terms invented by Truszynski and Armstrong but had emerged in the aerospace industry in the late 1950s as the air force started talking about a successor to the X-15 capable of a speed of Mach 12.) Along with Truszynski, an expert on radar tracking and telemetry instrumentation, Armstrong wrote a number of papers on instrumentation ranges for aircraft, including classified ones that dealt with even more advanced test ranges “where we were proposing taking off from a Caribbean island and flying westbound against the Earth’s rotation and landing at Edwards, which could allow you to get quite high Mach numbers in a relatively short space—into almost nearly orbital Mach numbers, while still being suborbital.”
Crossfield flew the X-15 a total of thirteen times before North American turned it over to NASA–air force–navy partnership. Armstrong watched as many of those flights as he could. Two of Crossfield’s flights were in the number-one airplane, the rest in number two. The highest speed he reached in any of them was Mach 2.9, the highest altitude 88,116 feet, and the farthest distance 114.4 miles. As Armstrong explains, “The contractor was expected to demonstrate certain basic, acceptable characteristics of the airplanes operationally, and that was a negotiation between buyer and seller. Beyond that, when it got into areas that had not ever been investigated, that was the responsibility of NACA/NASA.”
Armstrong was the last of the first group of NASA pilots to fly the X-15. The first to do so was Joe Walker, followed by Jack McKay. Walker, NASA’s senior pilot, flew after Crossfield’s eighth flight, and Major Robert M. White, the senior air force pilot, flew for the first time after Crossfield’s tenth. The air force wanted White to go before Walker, but negotiations between all the parties involved, which included the U.S. Navy, put NASA first. “I was not party to those discussions,” Armstrong notes. “The air force did like to set records—and that’s understandable. They could use that as a motivational tool and as a promotional, advertising tool to encourage people to join the air force, ‘That’s where the action is.’ I’ve never had any problem with that. Walker and White were sort of taking stair steps, the two of them, alternating flights, and the rest of us filled in behind. I was the most junior guy there, so I was kind of at the tail end, and that was fine with me.”
Armstrong did not fly the X-15 for the first time until November 30,1960. Prior to that, he did fly chase on two occasions, for Bob White’s flight past Mach 3 on September 10, 1960, and for the flight made five weeks later, on October 20, 1960, by Lieutenant Commander Forrest Petersen, the first successful program flight for the navy. In all, Neil flew chase for the X-15 on six occasions. Many more times than that, Neil was located in the Edwards control center, on the microphone with the pilot, and monitoring the radar and telemetry. The last time he flew chase as an Edwards employee was on June 29, 1962, when NASA colleague Jack McKay flew the number-two airplane nearly to Mach 5. After becoming an astronaut and transferring to Houston, he did fly chase one other time when he happened to be visiting Edwards on NASA-related business. This happened on August 15, 1964, during an X-15-1 flight piloted by Jack McKay, when Neil took NASA pilot John Manke with him for an “informal” chase: “We were interested in seeing how a T-38 would perform as a chase aircraft…. We were with the B-52 at launch and accelerated to about Mach 1.4, but we couldn’t make it back to Edwards in time for the X-15 landing.”
For the majority of X-15 flights, four chase planes were employed; in the longer-range flights, a fifth was added. Armstrong remembers his duties as chase: “We would have chase aircraft at the launch flying in formation with the B-52 with the X-15 under its wing and watching all the procedures. It helped to be knowledgeable about both airplanes [the X-15 and B-52], to know what you were watching for as they would go through the prelaunch checklist. If anything was going wrong, it was the chase pilot’s responsibility to report on what he could see at the back end—the business end—of the aircraft. If the engine lit [on the first try], then the X-15 pulled away very rapidly and the chase pilot just went home. On some flights the launch chase might be able to get to Edwards at the same time as the X-15. But most flights, he couldn’t beat him home. There were ‘catchers’ at the other end that would intercept, and sometimes there might be an ‘intermediate’ chase plane in case the X-15 landed at one of the intermediate landing fields. The job of the catcher was to look for the X-15—and it wasn’t easy to see sometimes—catch up, join up, and rendezvous with the airplane, so you were available if there was anything inside the X-15 that wasn’t working—airspeed, altitude, or so forth. We had windows break in the X-15; visibility in it was poor. For the X-15 pilot, it was nice to have somebody along, outside, looking at the airplane.”
At 10:42 A.M. Pacific time, on Wednesday, November 30, 1960, Armstrong sat in the cockpit of the number one airplane high over Rosamond Dry Lake anxiously waiting to be launched in an X-15 for the first time. At the controls of the B-52 drop plane were Major Robert Cole and Major Fitzhugh L. “Fitz” Fulton. Flying the chase planes for Neil were Joe Walker and Lieutenant Commander Forrest S. Petersen in F-104s and Captain William R. Looney in an F-100. Overall, it was the twenty-ninth flight in the X-15 program, the seventeenth involving the X-15-1, and the seventh made by a NASA pilot.
With Neil at the controls for the first time, the purpose of flight number 1-18-31 was simply pilot familiarization, but there was nothing ever very simple about flying the X-15. “The first one was just a checkout for me,” Armstrong relates. He had been in the X-15 simulators for hundreds of hours, but the real thing was very different. “When you’re dressed up in that pressure suit, and you get the hatch closed down on you, you find that it is a very, very confined world in there. The windshield fits over you so snugly that it’s very difficult to see inside the cockpit. You realize that this is a real different machine!” Looking out of the windshield, Neil saw nothing at all of the aircraft he was flying. “It’s exciting. There’s a lot of tension when you’re in that situation even though you know it’s been done before. Everybody else has been able to handle it, so you ought to be able to. Still, a high-tension time.”
At 45,000 feet, Fitzhugh in the B-52 started the same sort of countdown that would be used later in space shots: “Ten seconds, launch light is on. Five, four, three, two, one, launch.” Armstrong had been air-launched before, in the X-1B, but the X-15 came off much more dramatically, with more of a clank. Then came the challenge of getting the rocket motor started, right away.
The engine powering Neil’s X-15 was the XLR-11, built by Reaction Motors. The XLR-11 was comprised of two rocket motors, an upper and a lower. Each motor had four chambers and each chamber gave 1,500 pounds of thrust, a total of 12,000 pounds of thrust. But chamber number three, on the upper (number-one) engine, would not light, reducing the total thrust to 10,500 pounds. Even if up to four chambers had not been operating, the vehicle still could have been flown, though it
would have had to stay close to base and immediately enter into a constant turn that prepared it for landing. More than four chambers missing and the pilot had to shut down whatever chambers were firing, jettison fuel, and get down. Fellow test pilot Jack McKay, acting akin to what in the manned space program would come to be known as the “CapCom” (for capsule communications officer), told Neil to “go ahead and proceed with the original flight plan.”
If Reaction Motors had not been behind schedule with its new XLR-99 engine, Armstrong could have been flying a much more powerful machine. The XLR-99 produced 60,000 pounds of thrust, five times more than the XLR-11. Crossfield flew the new engine on contractor flights in November and December 1960, but the engine was not ready for government flights until March 1961. With the XLR-99, the X-15 could fly much faster and higher. But the original XLR-11, Neil explains, “gave us the ability to be flying the airplane and learning about its subsonic, transonic, and low supersonic characteristics. The landing would be the same as it would be with the bigger engine, so we faced the same challenges, learning how to properly get that thing onto the ground.” The first two flights Armstrong made in the X-15 were with the XLR-11, his last five with the more powerful XLR-99 engine.
Other than the number three chamber on the upper engine failing to light, Armstrong’s first X-15 flight went without incident. After the aircraft came level at 37,300 feet, Neil put it into an eight-degree climb that took him to an altitude of 48,840 feet before “pushover,” or nosing back downwards. His maximum speed was only 1,155 mph, or Mach 1.75, a fact that provoked him to say over the radio, “I bet those [chase] [F-]104s are outrunning me today.” At one point, Walker even taunted, “We’re overrunning you,” to which Neil countered, “No, you’re not.” But Walker and the rest were pleased with what they saw from Armstrong that day. During Neil’s approach to landing on Rogers Dry Lake, one that took place less than ten minutes after launch, Walker exclaimed, “Atta boy!” Armstrong answered teasingly, “Thanks, Dad,” his humorous moniker for the thirty-nine-year-old Walker, nine years his senior.
First Man Page 19