Time: 8:46 a.m. Pacific Daylight. Date: August, 1960. Place: 45,000 feet over the trackless wastes of the California-Nevada divide. Sealed in the cockpit of the X-15 rocket plane, Maj. Robert White, USAF project pilot on the X-15 program, crouches forward ticking off the final items on his countdown checkoff list. In the B-52 carrying the X-15 under its right wing, Maj. Fitzhugh A. Fulton, piloting the eight-jet mother ship, reaches the last item on his countdown.
"Ready to go, Bob?" he intones into his lip mike. "Any time," Bob White answers. The long, agonizing countdown is nearly over. White flicks a switch on his cockpit panel and the red launch light comes on in the B-52 cockpit.
"Starting count," Fulton says. "Five . . . four . . . three . . . two . . . one . . . drop!" A dull distant clunk is the only sound as the X-15 falls from the bomber's wing as it cruises at nearly 475 knots. "Clean break," the launch panel operator, back in the B-52's belly, shouts. The time: 8:48 a.m. PDT.
White waits a split second, then triggers the toggle switches firing up all eight barrels of his two XLR-11 rocket engines. A burst of rocket flames shatters the crystal-clear void as the engines ignite. Then, with staggering swiftness, the X-15 leaps forward hungrily. White's altimeter reads 40,000 feet; he has fallen nearly a mile in starting up. Above him, the B-52 has turned out of his way. The machmeter in the X-15 shoots through Mach 1 as if it never existed; for this bird it doesn't. White climbs to 60,000 feet, levels off for about one minute as he builds a surge of speed to 1,700 mph, then, burning on all eight rockets, points the X-15 toward the heavens.
The manned rocket plane streaks upward, casually leaving behind it in scant seconds the altitude marks of two decades. Far ahead and below, at Edwards AFB, USAF's Flight Test Center, radars reach up to track him after the chase planes lose the X-15.
As White touches his peak speed, two and a half Gs of acceleration force crush him back into the man-shaped seat of the X-15. But now, as he soars toward the top of his Keplerian arc, the acceleration forces begin to fade. Back and forth go the brief words of flight data as Bob White relays speed and altitude figures. He streaks past the last remaining record—the 126,200-foot mark set by the late Capt. Iven Kincheloe, Jr., in the X-2 four years earlier.
Climbing past 130;000 feet, Bob White feels his speed falling off. His rockets have long since burned out, their fuel expended in a four-minute energy climax that has shot him far beyond the stratosphere. Now he "milks" the plane for all the altitude he feels it can safely achieve. At 131,000 feet, White goes over the hump and starts back down, weightless for nearly a full minute.
White has exceeded the X-2 by nearly a mile, or so he thinks. But the instrumentation data betters his record: He has reached 136,500 feet, nearly twenty-six miles into the void of near space.
Peering out from the X-15's slitlike cockpit windows, Bob White perceives a world unseen by any other man. "Three distinct bands—the earth, the light blue of the sky, and then the very deep blue of extreme altitude" loom upward and around him. "It's fantastic," White declares.
Soaring downward to Edwards, he levels off at 52,000 feet, then makes ready for a 200-knot landing on Rogers Dry Lake at the Flight Test Center. The total elapsed time, from takeoff of the B-52 to landing of the X-15, clocks out at fifty-four minutes. The X-15 itself flew for just eleven minutes.
Eight days earlier, the X-15 had smashed the world's speed record, as veteran rocket pilot Joe Walker, X-15 project pilot for the National Aeronautics and Space Administration, crashed through to 2,196 mph, topping the old mark of 2,094 mph set in 1956 by the late Capt. Milburn G. Apt in the last flight of the X-2. In eight days, the X-15 has taken both speed and altitude marks; the X-15 now can only top itself as it reaches out faster and higher.
And this is just the beginning: White and Walker set their records with the scanty 16,000 pounds of power provided by the twin XLR-11 rockets (originally designed for the X-1 program). In the months and years ahead, with the 50,000-pound XLR (for Experimental Liquid Rocket) 99 engine—most powerful manned-rocket power plant in the world installed in the bird—the records should fall almost routinely.
Joe Walker will aim at working the X-15 up as fast as it will safely go—perhaps to 4,500 mph, Mach 7. Bob White will aim to fly literally out of this world—to beyond 250,000 feet if all goes right—nearly fifty miles, and possibly even higher. No other piloted aircraft should come close to the X-15 as it takes man out of his atmosphere and back to earth, in a series of fabulous flights blazing the trail for Dyna-Soar and later piloted orbital vehicles.
Latest in the proud line of USAF experimental research aircraft, the X-15 had its beginnings eight years ago when scientists of the old National Advisory Committee for Aeronautics (NACA), predecessor of NASA, projected the X-1 and the X-2 (which had just begun flying), into the future. NACA laboratories began studying the problems of piloted spaceflight; two years later they came up with the characteristics of the X-15 and with USAF and Navy worked up what has developed into one of the nation's outstanding examples of interservice and interagency cooperation. NACA would supply technical direction; USAF most of the funding and project leadership; Navy aided in funding, research, and testing.
After a fast and furious competition between Bell, North American, Republic, and Douglas for the challenge of building the new research vehicle, North American was given the go-ahead to build three X-15s in December of 1955. But there was far more to it than building three airplanes: In a single sweep man was biting off more speed and altitude than ever had been dreamed of.
The X-2 had not yet penetrated 2,000 mph; some doubted it could. The faster you went the worse be-Came the controllability problem, that pilot-killing never-never land where few had dared to tread. And beyond Mach 3, fuselage heating literally threatened to first twist, then melt airplanes. Battling both problems, NAA, NACA, and USAF scientists and engineers ran a series of different models through no less than twelve different wind tunnels until they felt the X-15's unique system of conventional aerodynamic and reaction jet controls could take it out of and back into the earth's atmosphere safely. Inconel-X, a space-age alloy of nickel and stainless steel, capable of standing up to 1,200 degrees F, was chosen for the skin of the new bird.
The death of USAF Capt. Mel Apt in 1956 in the record-shattering last flight of the X-2, which came just before construction started on the X-15, offered further proof of the necessity for a good pilot survival system. The MC-2 pressure suit, made of heat-resistant armor plate of aluminized nylon, was designed to provide pressure and oxygen to the pilots even if they had to eject at extreme altitudes. The specially designed rocket-powered ejection seat, with stabilizing fins and booms, was tested over and over again on the rocket sled test track at Edwards until the engineers were sure it would get an X-15 pilot safely out of a crippled plane and stop him from tumbling or spinning through space under the majority of the conditions the X-15 will experience.
In September of 1957, North American began building the three X-15 rocket planes. Even before construction began, the three engineering test pilots who had been chosen to fly the ship were contributing. Scott Crossfield, who had left NACA and joined North American smack at the onset of the program, was a veteran of experimental rocket flying, as was Joe Walker, who would be the primary NASA pilot. The late USAF Capt. Iven Kincheloe had already been chosen by USAF as its X-15 project pilot. The three, having flown all of our rocket-powered planes, the X-1, X-2, and D-558-II, as well as many other experimental research planes, could work alongside designers and engineers and come up with the pilot's view.
These were the first of a new breed, the combined aeronautical engineer-test pilot, with the unique talent and ability of being able to come back from a flight and report in precise scientific terms just what didn't work right. Crossfield would handle the contractor's demonstration flights, then turn the ships over to Walker and Kincheloe for high-performance testing.
The X-15 was to be a labor of love all the way: Rocket-and-experimental flying veterans, an elite corps scattered over the nation, found their way to the program. USAF's Maj. Arthur "Kit" Murray, who'd set the old 94,000-foot altitude record in the X-1, became Weapons System Project Officer for USAF, based at Wright-Patterson AFB. The WSPO concept, brand new with USAF in the X-15, aimed and beautifully succeeded at eliminating confusion, red tape, and divided authority by having one office tie all the loose ends together.
Q. C. Harvey, North American's X-15 Flight Test Chief, is a hardy holdover of the Bell rocket planes. The X-15 hangars at Edwards are the secret refuge of the dedicated specialists who have watched and worked on the X planes, from the original X-1 on up. They have watched, and cried, and cheered as they witnessed success and failure and progress in the blistering 110-degree heat of the Mojave summer and in the bone-chilling predawn cold of the winters. To them, what they do is not a job, it is a way of life; and development of each new untried experimental vehicle is for them like raising a child.
The pilots at Edwards, now highly trained and educated graduates of USAF's Flight Test Pilots School on the base, fly more securely knowing the painstaking skill of the men on the ground. When Bob White, then a captain and X-15 backup pilot, took over after Iven Kincheloe's untimely death escaping from a crippled F-104, the Edwards crew joined behind White. The X-15 was nearly ready to be rolled out up at North American's Los Angeles plant.
White, a tall, restless thirty-six-year-old World War II and Korean fighter pilot, was the least experienced of the X-15 crew. He had never flown rockets before. But after graduating in 1954 from the Flight Test Pilots School he worked over various phase-testing of the F-86, F-89, F-102, and F-105, and the VTOL X-13.
Ruggedly handsome, Bob White has a face cast in a permanently youthful and enduring mold. Like most of the new breed, he flies for love, yet in a businesslike fashion. His mind thinks in the brief, corrected staccato inputs demanded by computers—the jagged pieces of data that make up human instrumentation—the uniquely-manlike-yet-suggestive-of-machine capability of the space-age pilot.
After the X-15's rollout, White, along with Crossfield and Walker, began practice-flying X-15 missions before the rocket plane itself was ready. Using F-100s and F-104s, they flew "dirty configurations"—with engine throttled back, dive brakes popped, tail chutes open, and nose way down—simulating the X-15's high rate of sink-landing habits. At the same time, they commuted south to Los Angeles to get in "simulator time" in an X-15 cockpit rigged to computers at the North American plant. Before Bob White ever handled the X-15 in the air, he'd "flown" hundreds of missions, building experience at controlling the manned missile under the worst possible conditions.
Six months elapsed after the X-15's delivery to Edwards in October 1958 before it was ready for its first captive flights, slung under the mother B-52's wing. On June 8, 1959, after four captive tests, Scott Crossfield made the first glide flight and successful landing. The second X-15, which had arrived at Edwards in April, was captive-flown with a full fuel load on July 24. All went well, but one week later, on the ground, it was damaged by an explosion as the crew purged its fuel lines.
Plans went ahead nevertheless for the first powered flight of number-two X-15 and, on September 17, Crossfield successfully flew it with Bob White as chase pilot in an F-104. A second powered flight went smoothly, but on the third mission with power, an engine fire broke out as Crossfield ignited his rockets and, in an emergency landing on Rosamond Dry Lake, the X-15 broke in half behind the cockpit.
The flight test program was held up while all three X-15s were beefed-up. Finally, in February of 1960, the first X-15 was turned over to the Joint Operating Committee (JOC) of USAF and NASA, which together would run the high-performance testing. The big XLR-99 engine was still not ready; Walker and Bob White would test out the rocket plane first with the two smaller XLR-11 engines.
Late in March, Joe Walker made the first JOC flight in the X-15, climbing to 48,500 feet and reaching Mach 2. On April 13, Bob White made his first X-15 flight, achieving 48,000 feet and Mach 1.9. It was no trick; the trick was to hold back. Even with the small engines, the rocket plane was capable of far higher speeds and altitudes. Into the spring and early summer, the flights went forward, as Walker and White worked upward, extending the "speed and altitude envelopes" of the plane. On May 12, Walker exceeded Mach 3; one week later, May 19, Bob White went up to 107,000 feet, flying the number-one X-15.
The big XLR-99 engine, meantime, had arrived at Edwards and, after it was installed in number-three X-15, Crossfield and North American went ahead with plans for the first flight. But on the second ground runup, an explosion shook the plane; it blew in two, with Crossfield in the cockpit, and the nose section was hurled forward of the main section of the fuselage. Miraculously, Crossfield escaped injury in the blast and fire, which was traced to fuel-line leakage. But the X-15 suffered major damage, and the flight program was set back while a new engine was installed in one of the two remaining undamaged rocket planes.
Despite the setback, Walker and White kept right on flying the X-15 with the smaller engine, climbing the peak until they had gone as high and as fast as it would take the X-15. In September, the XLR-99 was ready to go, set to begin taking the X-15 even higher.
In his small green office in Flight Test Ops at Edwards, Bob White goes over the engineering data and plans his flights with the quiet precision of a man who knows he is taking a volatile machine and a fragile man far above where other humans can do much to help him. At the next desk over is Capt. Bob Rush-worth, White's backup pilot on the X-15 project. Against one wall is a foldup three-part cardboard photographic mockup of the X-15's cockpit layout. Every instrument, each switch, has been etched into their minds. This is thinking time; in the air, there are only split seconds for deciding what to do. The first move has to be the right one.
The danger? "Sure, flying the X-15's dangerous," White says quietly and slowly, "but the same element of risk is in a lot of jet flying. With the X-15 we'll build knowledge about aerodynamic heating, about control at extreme altitudes, about exit and reentry to and from the earth. . . about weightlessness, and how pilots react to this kind of flying. The pilots can and will adapt to any and all conditions they have to . . . instruments lack this talent."
Capable and cool, ready to fly in or out of the atmosphere, Bob White is a symbol of the new breed of aerospace pilot, set to head for space not in a missile, but in an airplane he commands. Just as man had conquered the wildernesses of new continents and unknown oceans, so he would take himself into space and bring himself back. Guided by a chain of developments that began with the first fabric and wood airplanes, and went forward into X-1 and X-2, he would carry on with X-15, Dyna-Soar, and beyond.
The author, Jules V. Bergman, is a pilot and aviation-space-science reporter for the American Broadcasting Company. He is the author of two forthcoming books—one on the X-15 entitled Ninety Seconds to Space—the X-15 Story, and the other on learning to fly.
Daily Report: Read the day's top news on the US Air Force, airpower, and national security issues.
Daily Report: Read the day's top news on the US Air Force, airpower, and national security issues.
Tweets by @AirForceMag