Ignition Sequence Start
The Apollo 11 F-1 Engine #5, and our space heritage.
Shadyside, Ohio, July 16, 1969. I assumed my regular position in front of the family black & white tv: head-first, laying flat on my belly, hands supporting my chin. I had been granted special temporary permission from my parents: a waiver to engage in unsafe television viewing (don’t sit so close to the screen, don’t squeeze your cheeks between your hands like that, for crying out loud, put your feet down!). That alone made the event important. I was excited, even though I wasn’t really sure what I was about to witness. Men were going to fly a spaceship to the Moon. I was all in, as any six year old boy had to be.
The picture was as good as you could expect. I could clearly make out the white needle that was the rocket, as well as the support tower through the morning Florida haze. A digital-mechanical clock super-imposed at the bottom of the screen counted down the time until launch. Walter Cronkite was providing the network commentary.
Occasionally the picture would begin rolling, which required delicate adjustment of the vertical hold control, an obscure plastic shaft located on the back of the set. As the tv warmed up, the fine-tuning collar that surrounded the channel knob required near-constant tweaking. One missed adjustment, one wrong twist of a knob or control, and your viewing window into space exploration history would be lost, never to return. No ability to record, pause, or rewind. Gone. In 1969, television was still a hands-on science. In my childhood mind, it required no less technical ability or risk taking than that of an astronaut.
Had NASA called me up back then, and asked me to join the program, I would have proudly accepted, gesturing toward the steady picture in the living room as proof of my technical prowess.
I turned up the volume, and heard a somewhat familiar voice speaking with authority.
Cape Kennedy, Florida. Jack King, known forever by some as the Voice of Apollo, spoke with his recognizable calm, monotone voice through the metallic-sounding public address speakers mounted at various locations facing the visitor stands. You could hear his microphone picking up the background murmur and pace of the control room.
(Edited June 12, 2015 — Jack King passed away June 11, 2015. He was 84 years old. ~ Rich)
Power transfer is complete. Forty seconds away from the Apollo 11 liftoff.
Four miles from the viewing area, and 363 feet atop the Apollo 11 Saturn V launch vehicle, three astronauts—Neil Armstrong, Buzz Aldrin, and Mike Collins waited for the first action and resulting reaction that would lift 6,200,000 pounds of rocket from the Earth and accelerate it into orbit, beginning their journey to the Moon and back.
At the opposite end of the stack, surrounded by four other Rocketdyne F1 engines dangling like a monstrous robotic foxglove from the bottom thrust structure of the Saturn V, center engine number five awaited the beginning of its first and last supper: a super-cooled, smelly mixture of refined kerosene and liquid oxygen that would be mixed together and force fed down its throat at the astonishing rate of 6,000 pounds per second. If everything operated correctly—if tens of thousands of components performed just as they were designed to, this dinner for all five engines would continue uninterrupted and unabated for the next two minutes and forty-five seconds.
Astronauts report it feels good. T minus twenty-five seconds…
The fuel and oxidizer tanks reached full pressurization, and the astronauts started hearing strange creaking and groaning noises from far below. Since the tanks were uninsulated, sheets of frosty ice formed on the outside skin of the vehicle. The cold contents inside were doing battle with the humid 85 degree ocean air of the Cape. What was not freezing was raining down around and onto the engines, and into the flame trench. Escaping vent gases swirled around and down the body of the spacecraft.
T minus fifteen seconds, guidance is internal.
The lowest tower arm pulled away from the first stage.
Twelve, eleven, ten, nine…
At precisely 8.9 seconds before liftoff, the S-1C engine start command was given.
Ignition sequence start.
The starting procedure was extremely complicated. Pressure-sensitive Hypergolic charges are set off, valves open, and the gigantic turbopumps quickly come up to speed. Engine #5 started slightly before the other four, to reduce structural loads on the vehicle. The astronauts could hear the valves banging open, the fuel and oxidizer rushing down the lines into the pumps, and the resulting explosions and vibration as all five engines came up to full thrust. The ice sheets began crashing down onto the launch pad, and were quickly vaporized by the intense heat. Parts of the concrete launch structure and flame trench melted to glass.
From zero thrust, all five engines were up and running—producing a combined 7.5 million pounds of thrust—in two seconds.
The hold-down arms released and the journey began. The four outside engines gimballed slightly to lean the spacecraft away from the tower until it was cleared (Engine #5 had no ability to gimbal: it was rigidly mounted to the bottom of the ship). Until the time that they rose above the launch tower, each engine had to do its part without failure of any kind. The first fifteen seconds were critical.
At the moment King shouted, “tower clear!”, the rocket had burned almost half a million pounds of fuel. Control and commentary was then handed over to Houston for the rest of the mission.
The Apollo 11 Saturn V first stage operated for less than three minutes to accelerate the entire spacecraft from zero to 6000 miles per hour while maintaining a proper trajectory.
Once its job was complete, center engine #5 was shutdown early to reduce the rapidly increasing acceleration. There were two reasons for this increase, that was now pushing the astronauts back in their seats at four times their weight. From the Apollo 11 Flight Journal:
The first is that the mass of the vehicle as a whole is dropping by over 13 tonnes every second. As a result, the engines have a decreasing mass to push against. A lesser factor is the rising efficiency of the engines as they rise out of sea-level air pressure into the near vacuum of the upper atmosphere. At sea-level, the atmosphere acts as an inefficient cap on an engine’s nozzle. In a vacuum, the exhaust gases can exit without hindrance. The result on the F-1 is a 20% rise in efficiency.
After all five engines were shut down, and its fuel and oxidizer tanks nearly empty, the first stage was jettisoned from the rest of the vehicle.
At forty-two miles high, the separated 280,000 pound first stage, including the massive engines, continued to climb ballistically another six miles. It then began its descent, impacting the Atlantic Ocean six minutes later.
Sinking three miles to the ocean floor, the Apollo 11 Saturn V S-1C stage would for nearly forty-five years remain as a dark, silent, immoveable memorial to extreme engineering.
At the same moment I was watching this historic event on the living room floor with my family in Ohio, a five-year old Jeff Bezos was sitting with his family in Texas, watching with the same unbridled excitement. Neither of us could have comprehended the enormity of what we were seeing. No one could have imparted the scale of the vehicle, the speeds, the temperatures, the fuel consumption, the weights, let alone the engineering that went into the mission. We didn’t give thought to what happened to the pieces after the mission was over.
Forty-four years later in March of 2013, I visited the National Air and Space Museum in Washington, D.C. There, inside the main foyer, I described to my daughter what was then the only tangible piece remaining of the Apollo 11 Saturn V, the command module that Buzz, Neil, and Mike used to safely return to Earth. Its name was Columbia, perhaps named after the Columbiad, the cannon shell “spacecraft” fired by a giant gun in Jules Verne’s 1865 novel From the Earth to the Moon. Its exterior, charred from its nearly 25,000 mile per hour reentry into Earth’s atmosphere on July 24, 1969, told a part of the Apollo story. This was the very same capsule I watched as a child on black & white tv. The same capsule that millions of people around the world focussed on for eight days in 1969. A relationship between man and machine. Something that we can point to, and use to explain history to those who were not there to experience it.
At nearly the same time that my daughter and I were examining the cramped interior of the command module, Jeff Bezos was commanding an expedition in the Atlantic Ocean, retrieving parts of two Saturn V F1 engines. One of the components, a thrust chamber, was later identified as being from Apollo 11's center engine #5. He had found the engines of that huge rocket that he and I watched from our living rooms; another tangible part of something that gave us, and many other kids of the sixties, inspiration. I was standing next to the top, while Bezos was pulling the bottom of the same historic rocket up from the deep, where it landed forty-five years ago.
These engines are now something we, our children, and their children will be able to look at, to see and touch, to be near. These objects were part of a program and an age that no longer exists.
As we celebrate Apollo 11's forty-five year anniversary, let us not forget that someday we will go back to the Moon. Men will set foot on Mars. We will be able to visit the sites where men and machines landed and conducted various experiments. Unchanged, these sites stand as a snapshot of our technical culture and ability, our fortitude, and our determination. It is vitally important that we preserve these sites and objects as carefully as possible, and protect them, in order that we may remind, enlighten, and excite future generations of space travelers.
There was indeed a time when the largest rockets left Earth for another celestial body. Mankind walked there, and returned home. It’s true… I saw it on tv.
Rich Dailey’s memoir, Heaven’s Machines releases in 2023.
