The rarefied conditions into which Armstrong “zoomed” in his sleek fighter jet were far closer to those on the Martian surface than anything down on Earth. Streaking upward past 45,000 feet he passed the biological threshold at which a person could survive without the protection of a spacesuit. When his near-vertical climb reached 90,000 feet, atmospheric pressure fell to a scant 6 millibars, about 1 percent of the pressure at sea level. Outside his cockpit, the temperature dipped to 60 degrees below zero F.
This was space. The only way to control his plane at the top of its ballistic arc was to invoke Newton’s Third Law and expel some steam via jets of hydrogen peroxide. A pilot in a near vacuum could maneuver his airplane in pitch, yaw, and roll just as manned spacecraft would later do. With all the energy from the zoom dissipating, Armstrong’s jet came close to a virtual standstill, sitting on its tail. For over half a minute at the top of his climb, he experienced a feeling of weightlessness. At about 70,000 feet, Neil had shut down the engine to prevent it from exceeding its temperature limit. The cockpit’s ingenious auxiliary pressurization system released a squirt of compressed gas.
The engine’s not running at the top of the arc was critically important to the goal of the flight test. If not shut down, the engine would have introduced yaw motions challenging Neil’s capacity to control the aircraft.
Streaking down nose-first into the atmosphere, enough air molecules eventually passed through the jet’s intake ducts to allow Armstrong to restart his engine, and, at a speed of about Mach 1.8, begin his recovery from the unpowered dive. From that point on, with luck, the rest of the flight was routine all the way down to the runway. If Neil did not get an engine restart, he could make a dead-stick landing. If necessary, in the moments after touchdown, he could pull a lanyard to deploy a drag chute housed just below the plane’s vertical stabilizer to decrease his landing rollout distance.
In this fashion, Neil Armstrong and his fellow NASA test pilots at Edwards—at the controls of a long pointy jet plane nicknamed “The Missile with a Man”—made the country’s first dramatic excursions to the edge of space.7 They did so for research purposes more than half a year before Commander Alan B. Shepard became the first American astronaut to fly in space.
These facts fly in the face of popular lore. Thanks to author Tom Wolfe’s 1979 bestseller The Right Stuff, and the 1983 Hollywood film adaptation, most people believe that the man who first flew in an airplane to the edge of space was U.S. Air Force test pilot Captain Chuck Yeager. Yeager made his December 10, 1963, flight in a rocket-equipped version of the Lockheed F-104A (designated NF-104A), the episode providing the stirring conclusion to Wolfe’s provocative account of the early days of the Space Age. Wolfe’s final sequence begins when four of the seven celebrated astronauts still had not flown into space, with the solitary Yeager taking the NF-104A up over Edwards, firing its auxiliary rocket motor, and zooming up so high that in the movie version Yeager glimpsed stars. Never mind that such a sight was optically impossible due to light reflecting off the Earth. Shooting for the stars—in an airplane named Starfighter—was the stuff of legend.
Reaching the dizzying height of 108,700 feet (Yeager wanted to set a new altitude record), his plane pitched up and went out of control. In his 1985 autobiography, Yeager claimed that a rocket thruster on the nose malfunctioned and stuck open, but some pilots at Edwards knowledgeable about the NF-104A and Yeager’s piloting of the aircraft that day have suggested that Yeager “plain screwed up,” letting his pitch attitude and angle of attack get away from him.8
Whatever caused its pitch-up, Yeager’s plane fell over on its back and went into a flat spin. Spiraling down and down from over twenty miles high, Yeager struggled to right himself. At 21,000 feet, he popped open the parachute rig stored in the tail of the NF-104A, a desperate move that failed to get him out of the spin. At 14,000 feet, he had no option but to eject. Blasted out of his plane, Yeager became entangled in his ejection seat and, awash in leftover rocket fuel, suffered horrible burns to his face and hands. As shown in the movie, he hit the ground hard and in excruciating pain. Nonetheless, Yeager resolutely got to his feet, loosely gathered up his chute, and, with flight helmet under his arm, walked almost staidly away from the burning wreckage toward an oncoming ambulance. That is, at least, the glorified Hollywood image. More accurately, a motorist from a nearby highway immediately rushed to assist Yeager, only to vomit at the sight of Yeager using the man’s penknife to cut off one of his lined gloves, as well as parts of two badly burned fingers stuck to the rubber lining.
Unfortunately, so much else about Yeager and his December 1963 flight as romantically inflated in The Right Stuff and elsewhere is factually inaccurate.9 Most important, Yeager and the U.S. Air Force Test Pilot School at Edwards were not responsible for “develop[ing] the first techniques for maneuvering in outer space,” as some air force publications and Web sites have claimed; NACA/NASA was, with the F-104 and previously with the X-1B. (The X-1B flights occurred between November 1957 and January 1958, but they were not effective in terms of reaction-control research.) And Yeager was not even close to being the first pilot to zoom into the high stratosphere. As we have seen, some NASA test pilots began to make zooms to 90,000 feet as early as the fall of 1960, a full three years prior to Yeager’s December 1963 flight. And in the rocket-assisted NF-104A, air force pilots performed zooms into the upper stratosphere before Yeager, as did Lockheed test pilot Jack Woodman.
Also, well before December 1963, a far more remarkable and historically significant flying machine had pushed the envelope considerably further than any zooming F-104. This machine was the X-15, the fastest and highest-flying manned winged vehicle ever built—and one that Chuck Yeager never flew. Conceived by the NACA in the early 1950s and built by North American Aviation (later North American Rockwell) under the sponsorship of the air force, the navy, and the NACA, the X-15 was constructed not just to explore the hypersonic flight regime existing above Mach 5 but also to study the possibilities of flying a winged vehicle outside the sensible atmosphere (the region where aerodynamic control surfaces will function). First flown in June 1959, the rocket-powered X-15 was a veritable “aerospace plane.” By the end of 1961, the year President Kennedy committed the nation to the Moon landing, the X-15 attained its primary design goals of flying to a speed in excess of Mach 6 (over 4,000 mph) and to an altitude of over 200,000 feet (or nearly thirty-eight miles high). In 1962, a year that saw the Mercury flights of astronauts Glenn, Carpenter, and Schirra, air force pilot Robert White, in a pressure suit similar to the Mercury space suit, flew the X-15 more than fifty miles high (264,000 feet), the altitude that technically qualified him as an “astronaut” according to a policy invented by the U.S. Air Force (and never endorsed by NASA). The total number of X-15 pilots who earned “astronaut wings” according to the air force definition was eight. That was one more than the original group of Mercury astronauts, only six of whom made it into space (and only four into orbit) as part of the Mercury program. (Mercury astronaut, Deke Slayton, did eventually fly into space, in 1975, as part of the Apollo-Soyuz Test Program.)
Following over thirty zooms in the F-104, Neil Armstrong would fly the X-15 seven times before joining the second class of American astronauts in September 1962. Neil never made it above the fifty-mile mark, but on April 20, 1962, in his sixth X-15 flight, he did reach 207,500 feet, just under forty miles high.
• • •
In retrospect, the movement of aeronautics from subsonic to transonic, then to supersonic and on to hypersonic (and beyond that to “hypervelocity”) seems inevitable. As the emerging Cold War crystallized into an atomic face-off between the United States and the Soviet Union, the sharpest focus for hypersonic enthusiasm lay in the development of an intercontinental ballistic missile (ICBM) armed with nuclear warheads. Yet for those enthusiasts for whom aeronautics still meant piloted, winged airplanes, the ambition was to design a rocket-powered vehicle to take men and cargo on hyperfast flights across global distances, on trajectories that, at their apex, flew out into space.
Rocket-powered experimental research airplanes were air-dropped into flight. Armstrong piloted his first on August 15, 1957, the first check-out flight of the modified X-1B, zooming to about 60,000 feet. Although it was the highest altitude that Armstrong had yet flown, at only 11.4 miles the dynamic pressure simply was not low enough to test the reaction controls.
In landing the aircraft, his nose landing gear “failed.” According to Neil’s official report, he “inadvertently touched down at 170 KIAS [Knots Indicated Airspeed], nose wheel first.” “It didn’t really fail,” Neil admits, “I broke it. I was landing on the lake bed, and it was fairly normal. But at touchdown the airplane began to porpoise and, after several cycles of the porpoising, the nose wheel bracketry failed. I felt devastated, of course, but that was improved a little when I found out that was the thirteenth or fourteenth time [due to the coupling of the geometry] that had happened [with the X-1 series].”
In his second flight in the X-1B on January 16, 1958,10 Armstrong remembers, “we dropped too close to Edwards Dry Lake [due to some systems problems on the X-1B], so we aborted the zoom.” The X-1B flew only one more time, on January 23, 1958, when Armstrong and Stan Butchart air-dropped pilot Jack McKay for a zoom to 55,000 feet, one that did not slow enough at the top to check out reaction controls. Immediately after McKay’s flight, mechanics found irreparable cracks in the rocket motor’s liquid oxygen tank (by then, the X-1B was about a ten-year-old plane), ending the entire X-1B program.
Supersonic jets differed from their slower predecessors in the design of their relatively shorter swept-back wings, denser shapes, and a much greater mass concentration around their fuselages. Unexpectedly, this altered geometry brought on some serious aerodynamic difficulties known as “roll coupling” (also called “inertial coupling” or “roll divergence”).
As Armstrong reported to work at the HSFS in the summer of 1955, no problem was receiving more attention than roll coupling. Not only was the problem endangering the F-100, it had also threatened the D-558-2, X-2, and the NACA’s newest research airplane, the Douglas X-3. A long, slender, dart-shaped aircraft that rates as one of the fastest-looking aircraft ever designed, the X-3 Stiletto experienced coupling instability during abrupt roll maneuvers that caused it to go wildly out of control. Built for Mach 2, the X-3 was barely able to reach Mach 1.2 because it never received the higher-rated-thrust turbojets intended for it. The NACA retired the plane, which was underfunded and lacked expected engine performance, in May 1956 after only twenty flights. So all the attention turned to the F-100. Quickly, a fix was found—the addition of a much larger tail. Then, flying its own modified F-100C, the NACA tested a new automatic control technique—one that used pitch damping as a means of lessening the divergence of the yaw—to resolve the roll coupling problem more generally. Armstrong checked out in the airplane on October 7, 1955, and piloted many of the flights for that program during the next two years.
This partially automatic flight-control system that Armstrong helped to develop for the F-100 was one of the first to incorporate “feedback compensation.” In essence, the idea was for the control surfaces on the aircraft (ailerons, rudder, elevator, and such) to communicate as part of an integrated, self-regulating system. What was needed for the X-15 was a novel system that automatically monitored and changed the “gains,” i.e., the ups and downs in voltage necessary to adjust the flight control system, without requiring too much work from the pilot.
The stability augmentation system used on the first two X-15s did not live up to expectations. Armstrong explains: “Because the X-15 covered such a wide speed range, it was impossible to set the gains in the flight control system to a single value that was optimum for all flight conditions. You had to continually be changing the gains because at one minute you’re at Mach 1, the next minute you’re at Mach 5.” This was “a complex and bothersome nuisance, a high workload environment.”
Starting in April 1960, Neil consulted with engineers at the Minneapolis-Honeywell Corporation on “a very unique, self-adjusting system.” After Honeywell installed the prototype system—called MH-96—on an F-101 Voodoo in early 1961, Armstrong traveled to Minnesota in March 1961 to fly it. Based largely on Neil’s favorable written reports, NASA decided to install the MH-96 on the final X-15 (X-15-3), which was scheduled to be test flown for the first time late in 1961. Given his role in the MH-96’s development, NASA assigned Armstrong to pilot the first flight.
In Minneapolis as at Edwards, Neil explains, “We used airplanes like the mathematician might use a computer, as a tool to find answers in aerodynamics.”
The NACA’s High-Speed Flight Station virtually invented the flight simulator for research purposes. In 1952, the NACA convinced the air force to buy an analog computer known as GEDA (Goodyear Electronic Differential Analyzer). Set up on the military base and maintained by electronics technicians, the inspiration and talent for turning the machine into a real flight simulator fell to two young engineers from the NACA, Richard E. Day and Joseph Weil. They programmed the necessary equations of motions into GEDA, gave it a simple broom-handle control stick, and set it up to “fly” what amounted to the first “virtual” airplane with a variation on “degrees of freedom” (roll; move forward and backward; and go up, down, and sideways). Day and Weil chose to give their pioneering simulator one freedom less, massively simplifying the overall equations by holding the forward speed constant. Changes in any one of the five flight quantities fed back into the program’s equations, changing the quantities of the other four.
By the time Armstrong arrived at Edwards, flight simulators had made important contributions to a number of research programs, notably the X-1B and the X-2, the latter of which the NACA was supposed to receive after the air force finished testing it. Unfortunately, a needless tragedy with the X-2 stopped that from happening.
Dick Day warned his air force associates not to push ahead so fast with the X-2, piloted by Iven Kinchloe, Frank “Pete” Everest, and Milburn G. Apt. Data from their work with the GEDA was confirming evidence from NACA wind tunnel tests that the X-2 would experience “rapidly deteriorating directional and lateral (roll) stability near Mach 3.” On April 25, 1956, the X-2 broke the sound barrier for the first time. Less than a month later, it flew past Mach 2. By midsummer it was pushing Mach 3. When Mel Apt took the X-2 up on September 27, 1956, for his very first flight in the aircraft, his flight plan called for “the optimum maximum energy flight path,” one that, without question, would rocket him past Mach 3—and into roll coupling.
The fatal crash happened just as Dick Day thought it might. At 65,000 feet and a speed of Mach 3.2, Apt lost control of the X-2 due to roll coupling and became unconscious. By the time he came to, it was too late. He died instantly when the plane screamed into the desert floor.
On the ground that day in the company of air force test pilot Iven Kinchloe, Armstrong observed the disaster from start to finish: “Mel’s flight was to be the last air force flight of the X-2 prior to turning the aircraft over to the NACA. So there was a good deal of interest in each X-2 flight. NACA HSFS was wedded to the concept of step-by-step testing so we were appalled that the air force would be putting any pilot on such a difficult profile on his first flight. In the air force quest for yet another record, they were deviating substantially from the NACA approach. So we tended to blame the air force officials for the accident, the loss of Mel, and the loss of the one-of-a-kind aircraft.”
The irony is that, in Mercury, Gemini, and Apollo, NASA did approximately the same thing as the air force did with the X-2. The difference was, in Armstrong’s view, that “our simulators in the space program were so much more sophisticated and accurate, and our preparation was so much more intense, that we convinced ourselves that the pilots could handle whatever situation we might encounter in flight.”
The Apt tragedy deepened the NACA’s commitment to the development of its research simulators. From GEDA and Dick Day’s other very early simulators came the Sim Lab, which Armstrong inhabited with increasing frequency: “I was often in the Simulation Lab at the request of one of our flight test engineers or simulation engineers to check out something about some simulator mechanization. We were trying to increase our understanding of aircraft handling qualities, damping limits, and what was causing instability.”
In the Sim Lab, Neil learned “that there were many ways to induce errors into the programming. Often the outputs to the instruments were improperly mechanized so the instrument would not accurately represent the airplane motions. I found this to be true much later in Houston and always took the time with a new simulator to check the accuracy of its response.”
“In those days, pilots didn’t really trust simulators,” remembers flight simulation programmer Gene L. Waltman, who came to work at the HSFS in July 1957, shortly before the transition from the NACA to NASA, “especially the older pilots.” For most of them, “what went on in a simulator just didn’t look or feel right.” Dick Day remembers one older pilot who after being coaxed into the Sim Lab and making a single simulation, said to Day, “ ‘Well, that’s enough. Let’s go to the bar.’ And that’s the way his actual flights looked.” On the other hand, according to Day, “Neil believed in the simulations. . . . because he could see the results.” “Always picking up new things and researching new things,” Armstrong may have spent more time in simulators than any other pilot then at Edwards.
Long before the Mercury astronauts “rode the wheel,” Armstrong also became one of the first NASA test pilots to endure the torture of the navy’s Johnsville centrifuge “to see whether the g field that you had to go through in a rocket-launch profile would adversely affect your ability to do the precision job of flying into orbit.” Armstrong explains the purpose of the research: “We hypothesized that it would be possible to pilot an aircraft into orbit—that a vertically launched rocket could be manually flown into orbit without the need for an autopilot or any sort of remote control.”
A team of seven pilots took part in the experiment: Armstrong, Stan Butchart, and Forrest “Pete” Petersen from the FRC; two other NASA pilots, one from Langley and one from Ames; and two air force pilots. Lying on their backs and strapped into molded seats contoured to fit the form of the individual pilot in his pressure suit, Armstrong and his mates were put through the wringer. Every possible force and stress and every possible flight condition was brought to bear on the pilots as they whirled dizzily at the end of the fifty-foot-long arm. At the highest speed and angle of the wheel, they experienced acceleration rates as high as fifteen g’s. Only a couple of the pilots handled g forces that high, and Armstrong was one of them. Gene Waltman, one of the FRC technicians on the scene, remembers Armstrong saying that at fifteen g’s so much blood left his head that he could only really see one of the instruments in the simulated cockpit. “I’d watch them get sick!” recalls Roger Barnicki, another FRC technician specializing in pilots’ flight suits. “Neil was not one that got sick. Neil was one that did his fifteen and got out of there!”
Neil recalls, “We persuaded ourselves at least—I don’t think we persuaded others—that it was, indeed, a doable task, operating the controls of a launch vehicle or aircraft accelerating at those high rates.” With FRC engineers Ed Holleman and Bill Andrews, Armstrong coauthored a NASA report announcing the surprising results. Many people in the aerospace community questioned the finding that g-forces up to about eight g’s actually had very little effect on a pilot’s ability to operate flight controls until it was proven to be true in the X-15 and Mercury programs.
Armstrong later went back to Johnsville to fly X-15 entry trajectories with various flight control system settings. “This was the most complicated centrifuge simulation ever created, as it attempted to provide a complete closed-loop simulation with the lateral and vertical components of the accelerations produced due to the pilot control actions reproduced in the centrifuge’s gondola cockpit.”
But the key component of X-15 flight preparation was the electronic simulator. Two main X-15 simulators were built. Both of them were analog machines, because digital computers were still far too slow to do anything in “real time.” North American erected the simulator called the “XD” on company property on what is now the south side of Los Angeles International Airport. Armstrong visited several times to experience the simulation of all six degrees of freedom. Flying down in an R4D, Day remembers Neil regularly asking for an ILS (instruments) approach into Los Angeles airport. “We did several flights down, basically entries. We would go up to 2,500 or 3,000 feet and we would do entries at different angles of attack and then plot angle of attack versus maximum dynamic pressure. It turned out to be a straight line, which was a special equation. And Neil learned that in case he had trouble.”
Under Dick Day’s direction, NASA built at Edwards an X-15 simulator that replicated the X-15 cockpit. According to Armstrong, the machine was “probably the best simulator that had ever been built up to that time, in terms of its accuracy and dependability.” In preparation for each one of his seven X-15 flights, he spent fifty to sixty hours in the simulator.
“The actual X-15 flights were only ten minutes long, and generally in the simulator you didn’t have the ability to do the landing,” Neil explains. “You’d just do the in-flight, and they were only a couple minutes long. We would put together a little team—the pilot, one of the research engineers, and one of the guys from the computer group—and say, ‘Here’s what we want to do,’ and they’d take what data we had and put it in and find out what we could learn from it. You could kind of begin to understand a problem.”
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.
Armstrong’s second X-15 flight, and his first for research purposes, came ten days later, just before the noon hour on Friday, December 9, 1960, also in the number-one airplane. Flight number 1-19-32 first tested the X-15’s newly installed “ball nose.”
Until this flight, the X-15, typical of all research aircraft up to this time, had a front-mounted boom with vanes to sense airspeed, altitude, angle of attack, and angle of sideslip in a free aerodynamic flow field. At such high altitudes and high speeds, the X-15 would melt its nose boom, destroying measurement data.
The ingenious solution was to design a sphere that could be mounted on the front of the aircraft. The sphere would be subject to the highest temperatures on the airplane, but it could be cooled from the inside by liquid nitrogen. Equidistant from the circumference were sensor ports in the middle of the ball as well as on the top and bottom. The “eight ball” moved automatically in pitch and yaw to keep the pressure equal on both of the ports, pointing the center hole directly into the free flow. The angle of the ball movement amounted to the airplane’s angle of attack. Similarly, the ball nose received precise indications of angle of sideslip and dynamic pressure, which then gave airspeed.
“It wasn’t a particularly difficult thing to fly for the first time, if it worked,” Armstrong explains. Dropped by the B-52 at the standard 45,000 feet over the Palmdale VOR station by Captain Jack Allavie and Major Robert Cole, the X-15 climbed to 50,095 feet at a speed of Mach 1.8. Burnout of the rocket came immediately after Neil extended the aircraft’s speed brakes. The ball nose worked extremely well, so well that it would be used throughout the remainder of the X-15 program. Neil’s own performance was, again, solid. Flying chase were Lieutenant Commander Petersen and Major Bob White in F-104s and Major Daniel in an F-100F. Upon touchdown, Joe Walker, acting as “NASA 1,” radioed up from the control center, “Real nice flight, boy!”
It would be over a year before Armstrong would make another X-15 flight. Throughout 1961, Armstrong continued to work on the new automatic flight-control system for X-15-3, the aircraft in which he would make his third through sixth X-15 flights starting in December 1961. Until then, there would not be nearly so much test flying for Neil as in previous years. But there would be more travel than ever, much of it done on commercial airliners, back and forth to Minneapolis-Honeywell and, even more so, to Seattle, where he consulted for NASA on the air force’s new X-20 space plane program, known as Dyna-Soar.
It would be in Seattle in late spring 1961 where one of the worst tragedies that could ever befall a young family began.