“And then on launch day it worked”: Marking the 50th anniversary of the first Saturn V launch (part 2)
by Charles Murray and Catherine Bly Cox
|Like everyone else at Marshall, Rudolph had thought that the all-up decision was madness—it was Rudolph to whom Mueller had said, “So what?” But whether all-up was madness or not, Rudolph was the man who had to implement it.|
Petrone watched through binoculars from across the marshy lake that separated the Launch Control Center from Pad 39A. The wind was blowing hard out of the north. Even from where Petrone was standing, he could see the wind meter spinning at the top of the tower and bits of debris swirling around. The winds were exceeding thirty-two knots, too high to launch, but Petrone’s weather chief assured him that they would be within limits by launch time. Petrone ordered the propellants team to begin loading. He remained at the Launch Control Center throughout the night, watching the tower. An hour before dawn, the wind began to fade.
When they had launched the first Redstones in the early 1950s, Albert Zeiler had crouched beside the slit window in the little blockhouse by the pad and watched as the engine fired up in pre-stage (with too little thrust to move the vehicle). He was deciding from the color of the flame whether the mix of fuel and oxidizer looked right. If the color was wrong, Zeiler told Debus (who stood beside him—the whole blockhouse was only a dozen feet square), and they shut down the engine and tried to figure out what the problem was. For the first launch of a Saturn V, 450 engineers and controllers were assembled in the Firing Room at the K.S.C. Launch Control Center, working at eight rows of consoles in a room 150 feet long and 90 feet wide. There was no human within three and a half miles of the vehicle itself, nor had there been since Corn’s team had begun to load the propellants eight hours earlier.
George Mueller waited in the large glassed-in viewing area set off at an angle toward the back of the Firing Room. Four years and one week had passed since he had sent his teletype to Marshall instructing them to fly the first Saturn V all-up. With Mueller sat others from headquarters, Seamans and Phillips among them. Not Webb, however, who always considered it his job to remain in Washington to cope with the political heat if something went wrong.
In the large Marshall contingent, sitting near Wernher von Braun, was Arthur Rudolph. Rudolph had been with von Braun for almost thirty-five years. The two of them had shared bachelors’ quarters in the early 1930s, and talked about going to Mars before they could even get their first liquid-fueled rocket, four and a half feet long, off the test stand. Today was Rudolph’s sixtieth birthday.
Like everyone else at Marshall, Rudolph had thought that the all-up decision was madness—it was Rudolph to whom Mueller had said, “So what?” But whether all-up was madness or not, Rudolph was the man who had to implement it, for he was the program manager for the Saturn, and therefore he was to Marshall and the Saturn what Shea and now Low were to Houston and the spacecraft. To get to this moment, Rudolph had surmounted years of engineering crises—the combustion instability on the F-l, the immature technology of the hydrogen-fueled J-2 engines in the upper two stages, endless difficulties in the construction of the S-II stage. Ever since Mueller’s decision, Rudolph’s worries had been augmented by the knowledge that, when this day came, he would be flying two stages that had never flown even once and a third stage that had never flown in this configuration. He hoped that he had been wrong and Mueller right.
Petrone was watching the countdown from his command post on Management Row. After the trials of the C.D.D.T., this countdown was proving to be startlingly smooth. In fact, as they approached T–3 minutes 7 seconds, they were right on schedule.
Some of the press buses didn’t leave the motels in Cocoa Beach until 6:00 that morning, but no one on board seemed worried about being late. Even if they got held up in traffic—not unlikely, considering the number of people trying to get onto Merritt Island to see the launch—it was inconceivable that A.S.-501 would launch on time, if it launched at all that day. During the last few months, everything involving the Saturn V had been late. As 7:00 approached, the buses were still inching their way up Route 3.
At T–3 minutes 7 seconds, control of the launch process was turned over to the computers. For almost three more minutes, Petrone would be able to stop the launch manually if he had to, but now the Saturn V was busy preparing itself to fly, receiving through the umbilical hoses still connecting it with the ground the helium that created the pressures within the propellant tanks necessary to feed the propellants into the pumps. At T–30 seconds, the 55,000-horsepower turbine that drove the S-IC’s five engines powered up. At T–8.9 seconds, an electrical signal was sent to the igniters, and four small, silent flames lit within the combustion chamber of each of the F-ls.
|Some of the press buses didn’t leave the motels in Cocoa Beach until 6:00 that morning, but no one on board seemed worried about being late… it was inconceivable that A.S.-501 would launch on time, if it launched at all that day.|
From that moment through liftoff, there was nothing Petrone or anyone else in the Firing Room could do. If something went wrong, the sensors would know it before the news could reach the Firing Room, and the Saturn V would shut down its engines without waiting for sluggish human beings to instruct them. So now the men in Management Row simultaneously swiveled around in their chairs—they got stuck if they didn’t do it at the same time—and put binoculars to their eyes. Through the bank of windows at the back of the Launch Control Center, they watched Pad 39A. Petrone kept his hand near the button that would close protective louvers over the windows if the Saturn V blew up, though he always suspected that, if it happened, he would just keep watching instead.
As soon as the sensors within the combustion chambers of the F-1s determined that the igniters were lit, the main LOX valves opened, releasing liquid oxygen into each combustion chamber where it combined with a fuel-rich combustion gas, an exhaust product from the turbine. The gas was comparatively cool—only 800 degrees Fahrenheit—and would help cool the nozzle during flight; now, it prepared the interior of the chamber for the thermal shock to come. This process took three seconds. The combustion of the exhaust gas produced a thick orange smoke.
At T–5.3 seconds, as sensors within each combustion chamber determined that the pressure at the face of the injector had reached 20 pounds per square inch, the main fuel valves opened and a torrent of kerosene burst through the painstakingly sized and angled orifices of the injection plate, past and through the copper baffles that had been redesigned so often. The streams of kerosene (a ton per second per engine) and liquid oxygen (two tons per second per engine) then impinged, formed their fans, and, mingling, ignited.
The viewing area for the press and V.I.P.s was across the road from the Launch Control Center. Bleachers were set up, with a corrugated iron roof to ward off sun and rain. At the top of a slight rise beside the bleachers, looking like so many unpretentious beach cottages built for a view of the sea, stood the little wooden studios with picture windows in front that the television networks had built for their launch coverage.
At T–8.9 seconds, the people in the bleachers could see an eruption of orange smoke pushing down and bouncing off the flame deflector under the launcher, then bursting out at either side. Then, a few seconds later, the flame directly under the engines turned to an incandescent white as the orange smoke billowed outward and upward, beginning to envelop the rocket. Still 501 didn’t move. Astronaut Mike Collins, who was hoping to ride a Saturn V someday, wondered momentarily whether this one was just going to sit there and be consumed in the holocaust.
The noise of the preparatory burn that had created the orange cloud was inaudible across the four miles separating the viewers from the launch site. Even as the engines went to mainstage and they saw the incandescent white flame, the sound had yet to reach them. For the people sitting in the viewing stand, the first seconds of the pyrotechnic display on Pad 39A remained eerily silent.
The main fuel valves in the S-IC’s five engines opened at slightly staggered intervals, so that neither launcher nor vehicle would have to withstand the pressure of all five engines coming to full power at the same instant. Now, as the fuel-injection pressure on each engine passed 1,060 pounds per square inch, a pressure switch sent a signal to the Instrument Unit (I.U.) high in the S-IVB stage of the stack, announcing that the thrust for that engine had reached 1.5 million pounds. At 7:00:00, the I.U., having tallied five good signals, sent a command from the vehicle through the electrical cables still connecting it to the earth, asking to be released.
At the base of the Saturn V, four hold-down arms restrained the rocket as the engines came up to mainstage power. The arms were massive, not so much to restrain the Saturn V from lifting off (the loaded weight of the Saturn V, over 6 million pounds, helped considerably to hold down the vehicle’s 7.5 million pounds of thrust) as to lessen the rebound load on the launcher if the engines were to shut down after reaching full power. In dealing with a normal liftoff, finesse was at least as important as strength, for all of the forces restrained by the hold-down arms were transmitted back into the structure of the Saturn V. To avoid putting stress on the body of the Saturn, the arms had been placed with great precision—Glover Robinson, the perfectionist engineer in charge of that operation, had used optical equipment to sight them in—and they had been designed so that there was absolutely no doubt whether they would simultaneously and instantaneously release the Saturn V upon command. Now, receiving the signal from the I.U., a helium-gas pneumatic device actuated the release, which occurred in all four arms within fifty milliseconds. If the pneumatic actuator had failed, an explosive bolt in each hold-down arm would have triggered the release.
|At the beginning, it seemed more a levitation than a liftoff—the Saturn rose so ponderously that it took more than ten seconds for it to clear the top of the umbilical tower.|
Still the Saturn V was not entirely free of the earth. When a vehicle producing 7.5 million pounds of thrust is suddenly and completely let go, the release itself produces an abrupt shock load. Rather than shockproof the vehicle to sustain this brief, one-time jolt, its designers tethered the Saturn V to the hold-down arms with soft steel bolts. Each bolt was an inch in diameter and protruded into a bell-shaped socket attached to the Saturn V. As the rocket began to lift, the soft steel was extruded through the sockets, giving the Saturn V a lingering release and attenuating the shock.
For the first milliseconds of its ascent, the Saturn V retained its umbilical plates. These plates, which held the fuel lines and electrical connections that would permit the Launch Control Team to regain control over the Saturn V if the engines were to shut down, remained connected until after liftoff—a lesson learned from M.R.-1 seven years before. After that instant of liftoff, however, the umbilicals could come out, for there was no possibility of the Saturn V rising an inch or two and then settling uneventfully back onto the pad as the Redstone had done. Once the Saturn V had moved even fractionally, the engines had to keep going or the Saturn would fall back, collapse, and explode. As the vehicle left the pad, it tripped two liftoff switches. Whereas until that moment it had been imperative that the umbilicals remain tightly connected to the rocket, it was now equally imperative that they disconnect.
Most of the connectors holding the umbilicals into the side of the Saturn V were of a ball-release type, meaning that when a pin within the umbilical was withdrawn, the balls which had been held in place by the pin collapsed, making the connection small enough to slip out. When the liftoff switches were tripped, the rods were pulled, the balls collapsed, and the umbilicals came free.
Now the swing arms, which carried the umbilicals and had given the Cape’s workers access to the Saturn V on the pad, had to get out of the way. For the Saturn V, there were nine arms on the umbilical tower, each weighing between ten and thirty tons and designed to be swung away—on a 73-degree arc for the bottom eight, a 135-degree arc in the opposite direction for the topmost arm containing the White Room. The arms had given the Cape more trouble than any other item in the ground support equipment except the crawler. At the moment of launch, four of them were safely out of the way, already retracted. The other five were called in-flight arms, meaning that they remained in place until after the hold-down arms had released and the vehicle was already in motion. First the outermost section of each arm retracted, and then the arms themselves began to swing, accelerating rapidly to get safely away from the vehicle. As the Saturn V slowly rose into the air beside them, the arms braked abruptly to avoid smashing into the umbilical tower.
For Don Buchanan, watching from the Launch Control Center, the hold-down period had seemed endless, until he had finally begun to think that his hold-down arms must somehow have failed after all. Now, as the Saturn lifted and all five in-flight swing arms moved smoothly away from the side of the vehicle, he began to breathe again.
As the Saturn V moved off the pad, the sound finally reached across the marsh and slammed into the viewing area. It came first through the ground, tremors that shook the viewing stand and rattled its corrugated iron roof. Then came the noise, 120 decibels of it, in staccato bursts. People who were there would recall it not as a sound, but as a physical force. In the C.B.S. broadcast booth, the plate-glass window began to shake so violently that Walter Cronkite had to hold it in place with his hands as he tried to continue his commentary.
One second after lifting off, only a few feet above the launch platform, 501 began to maneuver, yawing away from the umbilical tower. For the many viewers who didn’t know this was supposed to happen, the Saturn seemed to be tilting as ominously as the Vanguards and Atlases of only a few years earlier. Even for more knowledgeable viewers, it was a nervous moment. If everything was going nicely, why interfere by trying to steer the behemoth so soon? And yet that was what the I.U. was doing, sending a preprogrammed command to the engines of the F-l, which in response were gimbaling and guiding the Saturn V away from the umbilical tower.
At the beginning, it seemed more a levitation than a liftoff—the Saturn rose so ponderously that it took more than ten seconds for it to clear the top of the umbilical tower. Then, as the Saturn got farther from the ground, the scale of the F-ls’ inferno became more fully apparent: The rocket climbed, but the trail of flames continued to billow all the way down to the base of the launcher. Not until A.S.-50l was several hundred feet off the ground did its plume of flame lift from the launch platform.
|Today, in its first trial, they had launched a rocket the size and weight of a Navy destroyer, carrying eleven new engines, new fuels, new pumps, new technology of all kinds, and had done it perfectly. There was simply no way to explain it.|
Grady Corn, sitting on the lower level of the Firing Room in Propellant Row, was down too far to see the Saturn on the pad or the actual liftoff. All he knew was that the big windows in the Firing Room were vibrating violently and plaster dust was falling loose from the ceiling of the Launch Control Center onto his console. Now, as Corn looked back up at the window, the Saturn V came into view, rising majestically against a blue sky, and Grady Corn was cheering along with the rest of the team, jubilant that he had been so wrong.
Up in the V.I.P. viewing area, von Braun yelled, “Go, baby, go!” Arthur Rudolph decided he had gotten the finest birthday present of his life. George Mueller looked pleased.
Now the I.U.’s guidance system was controlling the rocket. Massive as the Saturn V seemed to an onlooker, it would not naturally go in a straight line. On the contrary, lacking a guidance system it would have been as unpredictable as a child’s skittering balloon. The job of the guidance system was to ensure that the line of thrust of the launch vehicle was aligned with the center of mass. To that end, the guidance system checked the vehicle’s position, attitude, velocity, propellant levels, and a few dozen other variables every two seconds, and then sent messages to the four outboard F-ls (the center engine was fixed). If an onlooker could have gotten close enough to see, and if he could have ignored the scale of the machine, the behavior of the F-ls would have seemed almost delicate, as each of the four engines swiveled briefly in small, tightly controlled arcs, a few seconds here, a few seconds there, not just maintaining the Saturn V in a steady climb, but guiding it through a complex trajectory that involved programmed changes in attitude as well as continual, ad hoc adjustments to compensate for wind.
At 135 seconds into the flight, as planned, the center engine of the S-IC shut down. Fifteen seconds later, the outboard engines did the same. Then a signal from the I.U. exploded a cord of explosive primer attached around the base of the S-II, cutting away the S-IC. As the final act of its two-and-a-half-minute lifetime, the S-IC fired eight small solid-fuel retro-rockets, slowing the S-IC so that the S-II would be safely separated when its engines ignited. The great S-IC quickly lost the rest of its upward momentum and, still carrying its exquisitely crafted pumps and piping and engines, fell back to crash into the Atlantic Ocean.
High above, eight small “ullage” motors on the S-II fired for four seconds to give the S-II a burst of acceleration and settle the propellants in their tanks. Then the five hydrogen-powered J-2 engines of the second stage came to life, developing a total of a million pounds of thrust. As the S-II accelerated, a second length of primer exploded, separating the “interstage”—the sixteen-foot part of the wall of the rocket that had covered the J-2 engines and connected with the top of the first stage.
The first Saturn V continued to perform perfectly. The five J-2 engines fired for six minutes, constantly gimbaling in their delicate minuet. They too shut down precisely at the planned moment, the primer cord exploded, the retro-rockets pushed the S-II back and away, and the single J-2 engine on the S-IVB stage fired.
And still everything worked. The S-IVB fired for two minutes and twenty-five seconds, putting itself and the C.S.M. into a perfect orbit 118 miles high, with a speed of 17,400 m.p.h.
Eleven and a half minutes after it had lifted off the pad, A.S.-501 was over for the people at the Cape. It wasn’t over for the flight controllers at Houston—they would relight the S-IVB a few hours later, bringing the spacecraft back into the earth’s atmosphere at an entry speed of 25,000 m.p.h. But it was over at Cape Kennedy, where the 450 men crowded into the Firing Room had cheered again with each new report of success and were now a little groggy.
A.S.-501, which the newspapers called Apollo 4, made the headlines the next day. But there was no way that the papers could convey what a von Braun or Petrone or Mueller—or, for that matter, a Rigell or Fannin or Corn—knew. Only a few years earlier, many of them had been hesitantly trying, often failing, to launch rockets with a single, small engine in each stage. Today, in its first trial, they had launched a rocket the size and weight of a Navy destroyer, carrying eleven new engines, new fuels, new pumps, new technology of all kinds, and had done it perfectly. There was simply no way to explain it. They could recite how heavy it was and how powerful and how many parts it contained, but that didn’t capture it. “We fought that thing for seventeen days,” Ike Rigell said, remembering the tortuous C.D.D.T. “And then on launch day it worked. It worked beautiful.” Thinking back on it, Rigell, a matter-of-fact man not given to exaggeration, could only shake his head and say, “It was fantastic. Unbelievable.” It was that, and more. A.S.-501 had opened the way to the moon.