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Apollo 11
Day 1, part 1: Launch
Corrected Transcript and Commentary Copyright ? 2008 - 2009 by W. David Woods, Kenneth D. MacTaggart and Frank O'Brien. All rights reserved.
Last updated 2015-12-02
Index to events
F-1 ignition sequence begins T-8.9 seconds
Lift-off 000:00:00
Pitch and roll maneuver 000:00:13
End roll maneuver 000:00:34
Abort mode I-B 000:00:42
Max-Q 000:01:23
Abort mode I-C 000:01:57
S-IC inboard cut-off 000:02:15
S-IC/S-II staging 000:02:42
Interstage separation 000:03:12
LET jettison & Abort mode II 000:03:18
S-IVB to COI (Abort mode III) 000:05:27
S-II inboard cut-off 000:07:41
Mixture ratio change 000:08:18
Abort mode IV 000:09:00
S-II/S-IVB staging 000:09:09
Parking orbit insertion 000:11:49
[The transcript begins over two-and-a-half hours before launch. With the Apollo 11 spacecraft sitting atop its Saturn V launch vehicle on Pad 39A, announcements on the progress of the countdown are made by the Public Affairs Officer (PAO) Jack King, the 'Voice of Apollo'.
The record of communications between the crew and the Mission Control Center, through 'CapCom' (the Capsule Communicator) commences soon after lift-off. This section of the journal will follow the flight through the launch and staging of the Saturn V launch vehicle, and insertion into Earth orbit about 12 minutes later. It concludes with the confirmation of orbital parameters and the safe check-out of the S-IVB third stage in orbit.]
[MP3 audio file. 1,947 kB.]
PAO (Public Affairs Officer):
This is Apollo Saturn Launch Control; T minus 2 hours, 40 minutes, 40 seconds and counting. At this time, the prime crew for Apollo 11 has boarded the high-speed elevator from inside the A level of the mobile launcher which is the second level inside the launcher. This is the high-speed elevator; 600 feet per minute which will carry them to the 320-foot level, the spacecraft level. Shortly, we'll expect astronauts Neil Armstrong and Michael Collins to come across Swing Arm 9, the Apollo access arm, and proceed to the white room and stand by to board the spacecraft. The third member of the crew, astronaut Edwin Aldrin, will be the last one to board the spacecraft, will stand by in the elevator seated in a chair while his two comrades first board the spacecraft. Once Armstrong, who sits in the left-hand seat, and Collins, who will sit in the right-hand seat during lift-off are aboard, then Aldrin will be called and he will take his seat, the middle seat in the spacecraft, The spacecraft Commander Neil Armstrong and the Command Module Pilot Michael Collins now proceeding across the swing arm into the small white room that attaches at the spacecraft level. In the meantime, about 100 feet below, we have a technician a team of technicians working on a leaking valve which is a part of the Ground Support Equipment, a part of the system that's used to replenish the fuel supply for the third stage of the Saturn V rocket. He is proceeding to tighten a series of bolts around this valve in the hope that this will correct the leak. Once the technicians do depart, the hydrogen will again be flowed through the system to assure that the leak has been corrected. The spacecraft Commander Neil Armstrong and CMP, the Command Module Pilot Mike Collins, now standing by in the white room. T minus 2 hours, 38 minutes, 45 seconds and counting; this is Launch Control.
The Shuttle Launch Experience mimics the lift-off.
우주왕복선 진수 체험(관)은 발사 순간을 흉내낸다.
Lift off pan and carefully peel off paper.
팬을 들어 올려 조심스럽게 종이를 벗긴다.
Lift chocolate off paper, using a thin knife if necessary.
필요하다면 얇은 칼을 사용해서 초콜렛을 종이에서 들어낸다.
Five, four, three, two, one, zero… We have lift-off.
5, 4, 3, 2, 1, 제로… 이륙했습니다.
The lid won’t lift (off).
뚜껑이 열리지 않는다.
Ten minutes to lift-off.
발사 10분 전.
Carefully lift the bread bowls off the custard cups.
커스터드 컵에 있는 빵 껍데기를 조심이 들어올려라
The plane lifted off on time.
비행기는 제 시간에 이륙하였다.
When the shuttle lifted off the launch pad, I almost cried.
우주왕복선이 발사대에서 이륙하자 나는 감격에 눈물 겨웠다.
The term stems from the days when a telephone handset was lifted off of a hook.
이 용어는 전화 송수화기가 들려진 데서 유래한 것이다.
Whenever the mouse is lifted off the surface, it shifts into a lower power mode.
표면에서 떨어질 때마다 마우스는 절전 모드로 전환된다.
The space shuttle won't lift off the launch pad until Sunday at the earliest.
우주 왕복선은 빨라야 일요일에나 발사대에서 이륙할 것이다.
I don’t seem to be lifting off.
몸이 뜰 것 같지 않아.
He has lifted off with the panel.
남자가 널빤지를 갖고 뛰어올랐다.
Our plane has lifted off the runway and is now airborne.
우리의 비행기는 활주로를 이륙하여 현재 비행 중이다.
http://history.nasa.gov/ap11fj/01launch.htm
PAO: This is Apollo Mission Control. Flight Director Cliff Charlesworth's team is on station here in the Mission Operations Control Room, ready to assume the control of this flight at tower clearance. There is a possibility that Apollo 11 will check out the Command Module color TV camera during the first Earth revolution while in contact with the Goldstone station. If this checkout does occur, we acquire Goldstone at 1 hour, 29 minutes elapsed time. We have loss of signal at 1 hour, 33 minutes, 50 seconds elapsed time. This TV camera checkout is a possibility. This is Mission Control, Houston.
[The commentary now resumes with the PAO at Launch Control, Florida.]
[MP3 audio file. 1,545 kB.]
PAO: This is Apollo Saturn Launch Control. We've just passed the 31-minute mark in our count. At T minus 30 minutes, 52 seconds and counting; aiming toward our planned lift-off time of 32 minutes past the hour, the start of our launch window on this, the mission to land men on the Moon. The countdown still proceeding very satisfactorily at this time. We've just got by an important test with the launch vehicle checking out the various batteries in the three stages and Instrument Unit of the Saturn V. We remain on external power through most of the count to preserve those batteries which must be used during the powered flight. We've just taken a look at them by going internal and then switching back to external again. The batteries all look good. The next time we go internal will be at the 50-second mark with those batteries and they will remain, of course, on internal power during the flight. The Lunar Module, which has been rather inactive during these latter phases of the count also is going on internal power at this time on the 2 batteries on the ascent stage and the 4 batteries of the descent stage. For the next 20 minutes we'll take a look at some systems in the Lunar Module, then power down at about the 10-minute mark in the count, power down the telemetry to preserve the power of the LM. The Lunar Module on Apollo 11, of course, when it separates from the Command Module in lunar orbit, will have the call sign Eagle. The Command Module call sign, once the two vehicles separate, will be Columbia. Both Columbia and Eagle are Go at this time. At 29 minutes, 24 seconds and counting; this is Kennedy Launch Control.
[At the very top of the launch vehicle, between the S-IVB and the spacecraft, is a 1-metre-tall ring called the IU (Instrument Unit). The ring's diameter matches the rocket stage below it. It carries systems concerned with the guidance and control of the vehicle. These include a digital computer and an inertially stabilised platform. With help from a theodolite located directly south of the vehicle, the platform is orientated to be aligned with the bearing the rocket is to take, 72° or ENE. This orientation will be maintained until just a few seconds before launch so that the turning of Earth does not take it out of alignment.]
[MP3 audio file. 3,899 kB.]
PAO: This is Apollo Saturn Launch Control. We've just passed the 26-minute mark in the count; T minus 25 minutes, 53 seconds and counting; still proceeding very satisfactorily. At this time Spacecraft Test Conductor Skip Chauvin working with astronaut Buzz Aldrin in the middle seat covering the final pressurization of the Reaction Control System for the spacecraft. These are those big thrusters on the side of the Service Module that are used for maneuvers in space. Each one of these thrusters is capable of 100 pounds of thrust [445 Newtons]; there are 16 of them located in 4 quadrants around the Service Module. We pressurize the system with helium prior to launch to make sure that all will be in readiness for use in space.
PAO: The countdown still proceeding satisfactorily. It picked up at the T minus 9-hour mark at 11:00 pm Eastern Daylight Time last evening. We've just had two comparatively minor problems since that time. The major portion of the countdown during the early morning hour; some five hours of work was taken to load the various propellants aboard the stages of the Saturn V launch vehicle. As we came into the count this morning, we did already have the fuel aboard the first stage, but it was necessary to bring the liquid oxygen aboard all three stages and the liquid hydrogen fuel aboard the second and third stages. Close to three-quarters of a million gallons of propellants were loaded during these 5 hours. Following that, the astronauts, the prime crew, were awakened at 4:15 am Eastern Daylight as planned in their countdown, and proceeded to have a physical examination in which they were declared flight-ready. They sat down for the normal astronaut fare on launch day, as far as breakfast is concerned; orange juice, steaks, scrambled eggs, toast and coffee. The three pilots were joined by two of their colleagues at breakfast, Director of Flight Crew Operations Deke Slayton, and the backup Command Module Pilot Bill Anders, who has been named the Executive Secretary of the National Aeronautics and Space Council. The astronauts departed from their crew quarters - After checking out their suits, they departed from the crew quarters at 6:27 am and some 27 minutes later, 8 miles away from the crew quarters at the Kennedy Space Center atop the launch pad at complex 39, 6:54 am, the commander, astronaut Neil Armstrong, was the first to board the spacecraft. He was followed about 5 minutes later by Mike Collins, and finally Buzz Aldrin, the man who is sitting in the middle seat during lift-off, was the third astronaut to come aboard.
PAO: Two minor problems have been encountered during the count. Early in the count, a malfunction light came on here in the control center indicating that we might have a communication problem at the launch pad. Nothing to do with the spacecraft, but it indicated we possibly might not be able to talk to some key technicians we had at the pad. The problem turned out to be very minor; a simple adjustment of some equipment beneath the pad remedied the problem. There was no, in fact, no equipment problem involved. The second problem, we did encounter a leaky valve in part of the equipment that's used to replenish the hydrogen fuel supply on the third stage of the Saturn V launch vehicle. A team of technicians were sent out to the launch pad at about the time the astronauts were traveling to the pad. They tightened some bolts and we were able to bypass this valve and proceed with our countdown. The weather is certainly Go. It's a beautiful morning for a launch to the Moon. We expect a temperature of about 85 degrees in the Kennedy Space Center area. The wind's about 10 miles - 10 knots, rather, from the southeast, and the weather conditions in the round-the-world track, according to reports from the Manned Space Flight Meteorology Group, indicate all weather conditions are acceptable for launch. That's our general status. We've just passed the 22-minute mark in the count. 21 minutes, 55 seconds and counting; this is Kennedy Launch Control.
[MP3 audio file. 1,471 kB.]
PAO: This is Apollo Saturn Launch Control. We're now less than 16 minutes away from the planned lift-off of the Apollo 11 space vehicle. All still going well with the countdown at this time. The astronauts aboard the spacecraft have had a little chance to rest over the last few minutes or so. At least they haven't been busy with procedures with the Spacecraft Test Conductor. In the meantime we have been performing final checks on the tracking beacons in the Instrument Unit which is used as the guidance system during the powered phase of flight. Once we get down to the 3-minute-and-10-second mark in the countdown, we'll go on an automatic sequence. As far as the launch vehicle is concerned, all aspects from there on down will be automatic, run by the ground master computer here in the firing room. This will lead up to the 8.9-minute [means 'second'] mark in the countdown when the ignition sequence will begin in those five engines of the first stage, the S-IC stage of the Saturn V. At the 2-second mark we'll get information and a signal that all engines are running, and at the zero mark in the countdown, once we get the commit signal, the signal that says that the thrust is proper and acceptable, we then will get a commit and lift-off as the hold-down arms release the vehicle. We have some 7.6 million pounds of thrust pushing the vehicle upward, a vehicle that weighs close to 6½ million pounds. We're now at 14 minutes, 30 seconds and counting, and this is Kennedy Launch Control.
[MP3 audio file. 1,098 kB.]
PAO: This is Apollo Saturn Launch Control. We've passed the 11-minute mark. Now T minus 10 minutes, 54 seconds on our countdown for Apollo 11. All still Go at this time. The astronauts in the spacecraft busy again. The Commander Neil Armstrong has performed some final switch settings for the Stabilization and Control System of the spacecraft. The spacecraft also now is on full internal power. This came shortly after the 15-minute mark. Spacecraft now on the full power of its fuel cells. Up to this time, it had been sharing the load with an external power source. Both Armstrong and Buzz Aldrin have armed their rotational hand controllers - the controllers they use in flight - and we have now gone to automatic system with the Emergency Detection System. That system - it would cue the astronauts if there's trouble down below with the Saturn V rocket during the powered flight. We're now coming up on the 10-minute mark. Ten minutes away from our planned lift-off. Mark T minus 10 minutes and counting, T minus 10. We're aiming for our planned lift-off at 32 minutes past the hour. This is Kennedy Launch Control.
[MP3 audio file. 1,544 kB.]
PAO: This is Apollo Saturn Launch Control. We've passed the 6 minute mark in our countdown for Apollo 11. Now 5 minutes, 52 seconds and counting. We're on time at the present time for our planned lift-off of 32 minutes past the hour. Spacecraft Test Conductor, Skip Chauvin, now has completed the status check of his personnel in the control room. All report they are Go for the mission, and this has been reported to the Test Supervisor, Bill Schick. The test supervisor now going through some status checks. Launch Operations Manager Paul Donnelly reports Go for launch. Launch Director Rocco Petrone now gives a Go. We're 5 minutes, 20 seconds and counting. Coming up shortly, that swing arm up at the spacecraft level will come back to its fully retracted position. This should occur at the 5-minute mark in the count. In the meantime the Lunar Module telemetry has been powered down. We took a good look at Eagle, and it looks good. The Spacecraft Test Conductor for the Lunar Module reported that Eagle was Go. The swing arm now coming back to its fully retracted position as our countdown continues. T minus 4 minutes, 50 seconds and counting. Skip Chauvin informing the astronauts that the swing arm now coming back. The astronauts will have a few more reports coming up in the countdown. The last business report will be from Neil Armstrong at the 45-second mark in the count when he gives the status on the final alignment of the Stabilization and Control System. We're now passing the 4 minute, 30 second mark in the countdown - still Go at this time.
[MP3 audio file. 2,539 kB.]
PAO: Four minutes, 15 seconds - the Test Supervisor now has informed Launch Vehicle Test Conductor Norm Carlson, you are Go for launch. From this time down, Carlson handles the countdown as the launch vehicle begins to build up. We're now hitting the 4-minute mark. Four minutes and counting. We are Go for Apollo 11. We'll go on an automatic sequence as standing at 3 minutes and 7 seconds.
PAO: Three minutes, 45 seconds and counting. In the final abort checks between several key members of the crew here in the control center and the astronauts, Launch Operations Manager Paul Donnelly wished the crew, on the launch teams' behalf, "Good luck and Godspeed."
PAO: Three minutes, 25 seconds and counting; we're still Go at this time. We'll be coming up on the automatic sequence about 10 or 15 seconds from this time. All still Go at this time. Neil Armstrong reported back when he received the good wishes: "Thank you very much. We know it will be a good flight." Firing command coming in now. We are on the automatic sequence. We're approaching the 3 minute mark in the count. T minus 3 minutes and counting. T minus 3 - we are Go with all elements of the mission at this time. We're on an automatic sequence as the master computer supervises hundreds of events occurring over these last few minutes.
PAO: T minus 2 minutes, 45 seconds and counting. The members of the launch team here in the control center monitoring a number of what we call red-line values. These are tolerances we don't want to go above and below in temperatures and pressures. They're standing by to call out any deviations from our plans. Two minutes, 30 seconds and counting; we're still Go on Apollo 11 at this time. The vehicle starting to pressurize as far as the propellant tanks are concerned, and all is still Go as we monitor our status board. Two minutes, 10 seconds and counting. The target for the Apollo 11 astronauts, the Moon, at lift-off, will be at a distance of 218,096 miles away. We just passed the 2-minute mark in the countdown. T minus 1 minute, 54 seconds and counting. Our status board indicates that the oxidizer tanks in the second and third stages now have pressurized. We continue to build up pressure in all three stages here at the last minute to prepare it for lift-off.
[MP3 audio file. 1,861 kB.]
PAO: T minus 1 minute, 35 seconds on the Apollo mission, the flight to land the first men on the Moon. All indications coming in to the control center at this time indicate we are Go. One minute, 25 seconds and counting. Our status board indicates the third stage completely pressurized. Eighty-second mark has now been passed. We'll go on full internal power at the 50-second mark in the countdown. Guidance system goes on internal at 17 seconds leading up to the ignition sequence at 8.9 seconds. We're approaching the 60-second mark on the Apollo 11 mission.
PAO: T minus 60 seconds and counting. We have passed T minus 60. 55 seconds and counting. Neil Armstrong just reported back: "It's been a real smooth countdown". We've passed the 50-second mark. Power transfer is complete - we're on internal power with the launch vehicle at this time. 40 seconds away from the Apollo 11 lift-off. All the second stage tanks now pressurized. 35 seconds and counting. We are still Go with Apollo 11. 30 seconds and counting. Astronauts report, "It feels good". T minus 25 seconds.
PAO: Twenty seconds and counting. T minus 15 seconds, guidance is internal. Twelve, 11, 10, 9, ignition sequence starts...
[The F-1 engine has a complex ignition sequence which will be described here. First, a description of the engine.]
Labelled diagram of F-1 engine
[ A large combustion chamber and bell have an injector plate at the top, through which RP-1 fuel and LOX are injected at high pressure. Above the injector is the LOX dome which also transmits the force of the thrust from the engine to the rocket's structure. A single-shaft turbopump is mounted beside the combustion chamber. The turbine is at the bottom and is driven by the exhaust gas from burning RP-1 and LOX in a fuel-rich mixture in a gas generator. After powering the turbine, the exhaust gases pass through a heat exchanger, then to a wrap-around exhaust manifold which feeds it into the periphery of the engine bell. The final task for these hot gases is to cool and protect the nozzle extension from the far hotter exhaust of the main engine itself. Above the turbine, on the same shaft, is the fuel pump with two inlets from the fuel tank and two outlets going, via shut-off valves, to the injector plate. A line from one of these 'feeds' supplies the gas generator with fuel. Fuel is also used within the engine as a lubricant and as a hydraulic working fluid, though before launch, RJ-1 ramjet fuel is supplied from the ground for this purpose. At the top of the turbopump shaft is the LOX pump with a single, large inlet in-line with the turboshaft axis. This pump also has two outlet lines, with valves, to feed the injector plate. One line also supplies LOX to the gas generator. The interior lining of the combustion chamber and engine bell consists of a myriad of pipework through which a large portion of the fuel supply is fed. This cools the chamber and bell structure while also pre-warming the fuel. Lastly, an igniter, containing a cartridge of hypergolic fluid with burst diaphragms at either end, is in the high pressure fuel circuit and has its own inject point in the combustion chamber. This fluid is triethylboron with 10-15% triethylaluminium.]
[At T minus 8.9 seconds, a signal from the automatic sequencer fires four pyrotechnic devices. Two of them cause the fuel-rich turbine exhaust gas to ignite when it enters the engine bell. Another begins combustion within the gas generator while the fourth ignites the exhaust from the turbine. Links are burned away by these igniters to generate an electrical signal to move the start solenoid. The start solenoid directs hydraulic pressure from the ground supply to open the main LOX valves. LOX begins to flow through the LOX pump, starting it to rotate, then into the combustion chamber. The opening of both LOX valves also causes a valve to allow fuel and LOX into the gas generator, where they ignite and accelerate the turbine. Fuel and LOX pressures rise as the turbine gains speed. The fuel-rich exhaust from the gas generator ignites in the engine bell to prevent backfiring and burping of the engine. The increasing pressure in the fuel lines opens a valve, the igniter fuel valve, letting fuel pressure reach the hypergol cartridge which promptly ruptures. Hypergolic fluid, followed by fuel, enters the chamber through its port where it spontaneously ignites on contact with the LOX already in the chamber.]
PAO: ...6, 5, 4...
[Rising combustion-induced pressure on the injector plate actuates the ignition monitor valve, directing hydraulic fluid to open the main fuel valves. These are the valves in the fuel lines between the turbopump and the injector plate. The fuel flushes out ethylene glycol which had been preloaded into the cooling pipework around the combustion chamber and nozzle. The heavy load of ethylene glycol mixed with the first injection of fuel slows the build-up of thrust, giving a gentler start. Fluid pressure through calibrated orifices completes the opening of the fuel valves and fuel enters the combustion chamber where it burns in the already flaming gases. The exact time that the main fuel valves open is sequenced across the five engines to spread the rise in applied force that the structure of the rocket must withstand.]
PAO: ...3...
graph of engine thrust rise during F-1 startup
[This diagram shows how the thrust rose during the start-up of each engine. It takes two seconds for full performance to be attained on all engines once the first has begun increasing. The engines are started in a staggered 1-2-2 sequence so that the rocket's structure would be spared a single large load increase, with the centre engine being the first to start. The outboard engines exhibit a hiccup in their build-up due to the ingestion of helium from the pogo suppression system installed in each one. The centre engine does not have this installed.]
[As the flow of fuel and LOX rises to maximum, the chamber pressure, and therefore thrust, is monitored to confirm that the required force has been achieved. With the turbopump at full speed, fuel pressure exceeds hydraulic pressure supplied from ground equipment. Check valves switch the engine's hydraulic supply to be fed from the rocket's fuel instead of from the ground.]
PAO: ...2, 1, zero, all engine running, LIFT-OFF!
[Public Affairs Officer Jack King, whose coolness is legendary, finally succumbs to the tension and is clearly heard to say "all engine running" instead of "all engines running".]
PAO: We have a lift-off, 32 minutes past the hour. Lift-off on Apollo 11.
[MP3 audio file. 2,899 kB.]
[MP3 audio file (11,435 kB) of the entire air/ground audio during ascent to orbit, but without the PAO's commentary.]
000:00:04 Armstrong: Roger. Clock.
PAO: Tower cleared.
[As planned, control of the flight now passes from the Launch Control Center at Cape Kennedy, Florida to the Mission Control Center in Houston, Texas. There, communication with the crew is handled by an astronaut sitting at the CapCom console; in this case, Bruce McCandless. The PAO also switches, and Jack King relinquishes the commentary to the Houston PAO, whose voice is heard from now on.]
000:00:13 Armstrong: Roger. We got a roll program.
000:00:15 McCandless: Roger. Roll. [Long pause.]
PAO: Neil Armstrong reporting their roll and pitch program which puts Apollo 11 on a proper heading. Plus 30 seconds.
[When it sat on the launch pad, the space vehicle's coordinate system matched the cardinal points of Earth's geograpic system. Its X-axis pointed straight up and its Y-axis pointed to true north. The third component of this system, the Z-axis, therefore was pointed directly west. Before it begins to tilt over, the vehicle needs to roll 18° so that the minus X-axis, previously facing east, faces along the planned heading, in this case 72° east of north. Then the tilt motion will be a simple pitch motion around the Y-axis.]
[Prior to the roll maneuver, the vehicle executed a small yaw maneuver to deliberately lean away from the launch tower during its first few seconds of ascent.]
[20.6 seconds after launch, the Saturn's guidance system aims the four outboard engines slightly away from the centreline of the vehicle. This is in case an outboard engine fails whereupon the resultant off-centre thrust vector would be nearer to acting through the centre-of-mass of the rocket.]
000:00:34 Armstrong: Roll's complete and the pitch is programming. [Pause.]
000:00:44 Armstrong: One Bravo. [Long pause.]
PAO: One Bravo is a abort control mode.
[Like the Space Shuttle that came after it, the flight of a Saturn V had defined times during which, the means by which the crew could escape from a failing vehicle were defined. Unlike the Shuttle with its solid rocket boosters which gave no escape option, the Saturn had so-called 'abort modes' throughout its ascent.]
[For the first two of these, one-alpha and one-bravo, rotation rates exceeding ±4° per second in pitch and yaw, ±20° per second in roll would will entail an abort.] [The first 42 seconds were flown in mode one-alpha. If things went wrong, the Launch Escape Tower (LET) would lift the Command Module away from the booster. The problem is that the CM needs to be taken away out to sea and the vehicle has not yet imparted much horizontal velocity. Therefore, a small 'pitch control' motor would additionally fire to send the CM away from the vicinity of the impending conflagration. The CM then goes through an automatic sequence to carry out a safe landing on Earth.]
[Mode one-bravo is similar except the pitch control motor is dispensed with since the vehicle would have tilted over enough to aim a CM out to sea. Instead, during an abort, a pair of canards at the tip of the LET would deploy to force the CM-tower combination to adopt a CM-first attitude. This was because hypersonic testing had shown that the stack had a stable tower-frst attitude. This mode extends to about 35.5 km altitude.]
PAO: Altitude's 2 miles.
000:01:02 McCandless: Apollo 11, Houston. You're good at 1 minute.
000:01:06 Armstrong: Roger. [Long pause.]
PAO: Down range 1 mile, altitude 3, 4 miles now. Velocity 2,195 feet per second.
PAO: We're through the region of maximum dynamic pressure now.
[As it flies through the air, the rocket must withstand an aerodynamic pressure imparted by its speed through the molecules of the atmosphere. This is like the pressure felt on a hand stuck out of the window of a fast-travelling car. In the rocketry situation, two things are happening to vary this pressure: the vehicle's rising speed makes it higher; the rapidly thinning atmosphere brings it down. The interaction of these two variables leads to a point in the ascent when the aerodynamic pressure, denoted by the letter 'Q', reaches a peak. This is known as Max-Q and is the point when weaknesses in the rocket's structure are most likely to be found out. It occurs at 1 minute and 23 seconds into the flight.]
PAO: Eight miles down range, 12 miles high, velocity 4,000 feet per second.
000:01:54 McCandless: Stand by for Mode One Charlie.
000:01:57 McCandless: Mark.
000:01:58 McCandless: Mode One Charlie.
000:01:59 Armstrong: One Charlie.
PAO: Cliff Charlesworth taking a staging status.
[Mode one-charlie begins at an altitude of about 30.5 km. At this altitude and beyond, the air is too thin for the LET canards to be effective so control of the CM's attitude during an abort would initially go to the its maneuvering thrusters. The safe range for vehicle rotation changes to be ±9° per second in pitch and yaw, ±20° per second in roll.]
000:02:03 McCandless: Apollo 11, this is Houston. You are Go for staging. [Pause.]
000:02:17 Armstrong: Inboard cut-off.
PAO: Inboard engines out.
000:02:19 McCandless: We confirm inboard cut-off. [Long pause.]
[The central or inboard engine of the Saturn V is shut down early to limit the vehicle's rapidly rising acceleration. There are two reasons for this rise. 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.]
Graph of Saturn V acceleration
[This graph is redrawn from the AS-506 Flight Evaluation Report. It shows how teh acceleration experienced by the crew varies over the course of the Saturn's ascent. The key events in the graph are:
Lift-off under S-IC power. Note how the acceleration rises rapidly as the propellant tanks empty and the engines increase in efficiency.
Cut-off of the central or inboard engine engine of the S-IC.
Cut-off of the remaining four outboard engines of the S-IC at a peak of 4g.
S-II stage ignition. Note the reduced angle of the graph. Although the mass of the first stage has been discarded, the thrust of the S-II stage is one ninth of the final S-IC thrust.
Cut-off of the inboard engine of the S-II at a peak of approximately 1.8g.
Change in mixture ratio caused by the operation of the PU valve. The richer mixture reduces the thrust slightly but also increases engine efficiency.
Outboard engine cut-off of the S-II at approximately 1.7g.
S-IVB stage ignition. Note again the reduced angle of the graph caused by the thrust being cut by a fifth.
With the cut-off of the S-IVB's first burn, the vehicle is in orbit and the acceleration drops to zero.
[The 4g experienced at the end of the S-IC burn is the highest that will be reached during ascent. The only time a greater g-force will be experienced during the mission is upon re-entry at the end when over 6g will be imparted on the crew.]
[The Saturn's guidance computer then performs 'tilt arrest'. Throughout the S-IC burn (and for the start of the S-II), the vehicle has been flying a series of pre-programmed maneuvers called the tilt sequence. The yaw at launch and the roll to align the rocket with the launch azimuth were two of these. The major maneuver of the tilt sequence has been a slow tilt towards horizontal as the vehicle climbs. Note that this form of guidance is not trying to aim for a particular point. It takes no account of where it is or how the winds are affecting it and so it described as open-loop guidance. At the end of the S-IC burn, it is no longer desirable to have the vehicle rotating whioe staging takes place so the tilt maneuver is stopped or arrested.]
PAO: Down range 35 miles, 30 miles high. Standing by for the outboard engine cut-down [means "shutdown"] now.
000:02:44 Armstrong: Staging.
[The S-IC first stage has shut down and separated from the S-II second stage.]
[The sequence for separation is as follows: Half a second after shutdown of the first stage, four ullage motors mounted around the interstage ignite, followed a fifth of a second later by a command to fire the first separation explosive and ignition of the eight retro rockets mounted in the conical fairings near the base of the S-IC. The two sets of rockets fire in opposite directions to pull the two sections of the vehicle apart. Physical separation comes soon after and half a second later, the J-2 engines on the S-II stage are started. The S-II ullage rockets were eventually deleted from the later Saturn V's. Ullage is a brewer's term for the space in a barrel taken up by air rather than liquor. The rocket people modify its use to mean the establishment of that space at the opposite end of a tank from the outlet so that the liquid leaves the tank cleanly without gas and with a degree of pressure to help it flow to the engine. They usually achieve this by firing small rockets to settle the tank's contents to one end.]
000:02:46 Armstrong: And ignition. [Pause.]
[The S-II stage carries five J-2 uprated engines which burn LH2 and LOX to produce a total of 5,141 kN (1,155,859 pounds) thrust. The engine design allows for restarting in flight but this feature is only implemented in the engine used in the S-IVB.]
Labelled diagram of J-2 engine
[The thrust chamber and bell of each engine is fabricated from stainless steel tubes brazed together in a single unit. Supercold LH2 is pumped through these tubes to cool the thrust chamber and simultaneously prewarm the fuel. The engine carries two separate turbopumps, both powered in turn by the exhaust from a gas generator which burns the stage's main propellants. The hot gas exhaust is fed from the gas generator, first to the fuel turbopump, then to the LOX turbopump before being routed to a heat exchanger and finally into the engine bell. The fuel and LOX outputs of both turbopumps are fed, via main control valves, to the thrust chamber injector via the LOX dome. Unlike the solid steel injector of the F-1, the J-2 injector is fabricated from layers of stainless steel mesh sintered into a single porous unit. A solid LOX injector behind this carries 614 posts which pass LOX through the injector and into the combustion chamber. Each post has a concentric fuel orifice around it and these orifices are attached to the porous injector. The fuel delivery is arranged to ensure that about 5 percent seeps through the injector face to cool it, the rest passing through the annular orifices.]
[The ASI (Augmented Spark Igniter), fed with propellant and mounted to the injector face, provides a flame to initiate full combustion. Valves are provided to bleed propellant through the supply system well before ignition to chill all components to their operating temperatures otherwise gas would be formed which would interfere with the engine's use of propellant as a lubricant in the turbopump bearings. A tank of gaseous helium is fabricated within a larger tank of gaseous hydrogen. This is the Start Tank. The helium provides control pressure for the engine's valves while the hydrogen spins up the turbopumps before the gas generator is ignited. A PU (Propellant Utilization) valve on the output of the LOX turbopump can open to reduce the LOX flowrate. This adjusts engine thrust during flight to optimise engine performance.]
[To start the J-2 engine, spark plugs in the ASI and gas generator are energised. The Helium Control and Ignition Phase valves are actuated. Helium pressure closes the Propellant Bleed valves, it purges the LOX dome and other parts of the engine. The Main Fuel valve and the ASI Oxidiser valves are opened. Flame from the ASI enters the thrust chamber while fuel begins to circulate through its walls under pressure from the fuel tank. After a delay to allow the thrust chamber walls to become conditioned to the chill of the fuel, the Start Tank is discharged through the turbines to spin them up. This delay depends on the role of the engine. A one second delay is used for the S-II engines. Half a second later, the Mainstage Control Solenoid begins the major sequence of the engine start. It opens the control valve of the gas generator where combustion begins and the exhaust supplies power for the turbopumps. The Main Oxidiser valve is opened 14° allowing LOX to begin burning with the fuel which has been circulating through the chamber walls. A valve which has been allowing the gas generator exhaust to bypass the LOX turbopump is closed allowing its turbine to build up to full speed. Finally, the pressure holding the Main Fuel valve at 14° is allowed to bleed away and the valve gradually opens, building the engine up to its rated thrust.]
[As the thrust of each second stage engine reaches 65%, it causes its indicator light on the Main Display Console to be extinguished.]
[MP3 audio file. 6,224 kB.]
000:02:55 McCandless: 11, Houston. Thrust is Go, all engines. You're looking good.
000:02:59 Armstrong: Ah, Roger. You're loud and clear, Houston. [Pause.]
PAO: At 3 minutes, downrange 70 miles, 43 miles high, velocity 9,300 feet per second.
000:03:13 Armstrong: We got skirt sep.
000:03:15 McCandless: Roger. We confirm skirt sep.
[Between the first and second stages is a large ring, 10 metres in diameter to match the stages above and below, with a height of 5.5 metres. This ring, the interstage, is there to make room for the S-II's engines which protrude some distance below the bottom edge of the stage's wall. If, at staging, the interstage were to stay with the S-IC, there is a danger that any slight rotation of the massive first stage would cause contact between it and the engine bells on the S-II. Therefore a cut is made directly above the S-IC using a shaped explosive charge. This leaves the interstage attached to the S-II. However, the ring imposes a significant mass penalty on the second stage. So much so that it is considered a mandatory abort if the interstage doesn't separate. It too is dropped 30 seconds after the first separation. This gives time for the second stage engines to establish smooth acceleration with minimal rotation.]
[It is interesting to note that the interstage failed to separate on the Saturn V that lofted Skylab to space. Nevertheless, controllers allowed the S-II stage to continue and it successfully inserted the orbital workshop into orbit.]
000:03:17 Armstrong: Tower's gone.
000:03:19 McCandless: Roger, tower. [Pause.]
PAO: Neil Armstrong confirming both the engine skirt separation and the launch escape tower separation.
000:03:28 Armstrong: Houston, be advised the visual is Go today.
000:03:32 McCandless: This is Houston. Roger. Out.
000:03:36 Collins: Yeah, they finally gave me a window to look out. [Pause.]
[Although Armstrong as Commander has his own window through the Boost Protection Cover attached to the Launch Escape Tower, and Aldrin in the center couch can see through the hatch window above his head, Collins in the right-hand couch has had his windows covered up to this point.]
[With the loss of the escape tower, the flight moves to abort mode two. Now if the vehicle goes awry, the CSM would separate from the Saturn and either the Service Module's main engine or its small thrusters would be used to gain distance before the CM continues to a normal landing in the sea.]
[Six seconds after the jettison of the escape tower, the guidance mode of the Saturn changes from dumb to smart, from open loop to closed loop. This is the Iterative Guidance Mode (IGM) whereby the guidance system is now actively plotting a course to the point in space and velocity where it will insert the vehicle into orbit. While the Saturn was in the thicker parts of the atmosphere, it was undesirable to allow it to make large attitude changes, hence the pre-programmed tilt sequence. Now that the vehicle is essentially in a vacuum, the computer can react to its actual position and velocity and issue steering commands to the engines as required to reach its goal.]
000:03:44 McCandless: 11, Houston. Your guidance has converged; you're looking good.
000:03:52 Armstrong: Roger. [Pause.]
PAO: Downrange 140 miles, altitude 62 miles, velocity 10,300 feet per second.
000:04:01 McCandless: 11, Houston. You are Go at 4 minutes.
000:04:04 Armstrong: Roger. [Long pause.]
PAO: Apollo 11 right on the ground track.
PAO: 190 miles down range now, 72 miles high, velocity 11,000 feet per second.
PAO: Booster says it's looking good at 5 minutes.
000:05:03 McCandless: 11, Houston. You are Go at 5 minutes.
000:05:06 Armstrong: Roger. It'll - Apollo 11. Go. [Pause.]
PAO: Down range 270 miles, altitude 82 miles, velocity 12,472 feet per second.
000:05:21 McCandless: Stand by for S-IVB to COI capability.
[COI is Contingency Orbit Insertion. It is essentially abort mode three and means that if the S-II were to fail, the S-IVB would have the capability to take the stack far enough towards orbit where the Service Module could ignite its large main engine to place the CSM in Earth orbit. Of course, the spacecraft would not be able to depart for the Moon as the S-IVB's power would have been consumed in reaching orbit. Instead, the spacecraft would embark on a planned for, but hopefully unrequired Earth orbit mission.]
000:05:25 Armstrong: Okay.
000:05:27 McCandless: Mark. S-IVB to COI capability.
000:05:30 Armstrong: Roger.
PAO: Apollo 11 could now get into orbit using the S-IVB if necessary.
000:05:35 Collins: You sure sound clear down there, Bruce. Sounds like you're sitting in your living room.
000:05:39 McCandless: Ah, thank you. You all are coming through beautifully, too. [Long pause.]
PAO: Everyone is reporting Go here in the Control Center.
000:06:00 Armstrong: We're Go at 6 minutes. Starting the gimbal motors.
[In case the Service Module's engine has to be used in the event of an abort, power is applied to four gimbal motors that will slightly rotate the engine in its mount so that its thrust is applied through the spacecraft's centre of mass.]
000:06:03 McCandless: Roger, 11. You're Go from the ground at 6 minutes. [Long pause.]
000:06:20 McCandless: Apollo 11, this is Houston. Level sense arm at 8 plus 17; outboard cut-off at 9 plus 11. [Long pause.]
PAO: Level sense arm is the sequence that arranges the staging between the second stage and the third stage. The fuel uncovers a sensor starting that sequence. Predicting that will be uncovered at 8 minutes, 17 seconds with outboard engine cut-off 9 minutes, 11 seconds on the second stage.
000:07:01 Armstrong: Apollo 11's Go at 7 minutes.
000:07:04 McCandless: 11, this is Houston. Roger. You're Go from the ground at 7 minutes. Level sense arm at 8 plus 17; outboard cut-off at 9 plus 11.
000:07:09 Armstrong: Roger. [Long pause.]
PAO: Downrange 530 miles, altitude 95 miles, velocity 17,358 feet per second.
PAO: Apollo 11 is still right down the ground track. Still Go at 7 minutes, 41 seconds.
000:07:42 Armstrong: Inboard cut-off.
000:07:45 McCandless: Roger. We confirmed. [Long pause.]
PAO: Inboard engines are out, on the second stage as planned.
[Actually, it's just the one engine, the central engine in the cluster of J-2s. On early Saturn V flights, it was noted how severe vibrations would build towards the end of the S-II burn. The solution adopted from Apollo 10 onwards was to shut that engine down before the vibrations were expected.]
PAO: Apollo 11 Go on all sources.
000:08:19 McCandless: Apollo 11, Houston. You are Go at 8 minutes.
000:08:22 Armstrong: Ah, just got the mixture ratio shift.
000:08:24 McCandless: Roger. We got PU shift down here, too. [Pause.]
[The J-2 engine included a valve that allowed the mixture ratio (MR, the ratio of fuel to oxidiser) to be altered during the burn. This MR change was made to maximise propellant utilisation, hence the name PU shift.]
[On the S-II, the strategy was for most of the burn to be made at a high MR of 1:5.5 which also yielded the stage's maximum thrust. Once a specific velocity had been reached, which occurred 5 minutes, 31.8 seconds after the engines were commanded to start, the MR for the remaining four engines was reduced to 1:4.34 for the rest of the burn. The effect of this was two-fold: it reduced the thrust from the stage by a quarter but it also increased the specific impulse and therefore the efficiency of the engines. If engineers had the timing of the MR change right, the intention was that the LH2 and LOX should both be as close as possible to depletion when sensors in the tanks indicated it would be prudent to shut down the stage.]
[On the very early Saturn V flights (Apollos 4, 6 and 9), the timing was based on a closed-loop decision. Level gauges within the tank monitored how the propellants were being consumed and the change made based on that data. Mathematical modelling had shown benefits to an open-loop decision, one based on the change in MR occurring when a specific velocity had been reached.]
000:08:34 Collins: Well, it looks like a nice day for it. These thunderstorms down range is about all.
000:08:52 McCandless: 11, this is Houston. You are Go for staging. Over.
000:08:56 Armstrong: Understand, Go for staging. And...
000:08:57 McCandless: Stand by for Mode IV capability.
000:08:59 Armstrong: Okay. Mode IV.
000:09:00 McCandless: Mark.
000:09:01 McCandless: Mode IV capability. [Long pause.]
PAO: Mode IV on Apollo 11 could get into orbit using the Service Propulsion System now. Altitude is 100 miles, downrange is 883 miles. Outboard engine cutoff.
000:09:15 Armstrong: Staging, and ignition.
000:09:19 McCandless: Ignition confirmed. Thrust is Go, 11. [Long pause.]
PAO: And we have a good third stage now.
[The sequence of events for the first ignition of the single J-2 engine in the third stage is essentially the same as for the engines in the S-II (see earlier description). The main change is that the supercold fuel is allowed to flow through the walls of the thrust chamber to condition it for three seconds, instead on one, before the Start Tank discharges through the turbines, spinning them up in preparation for operation.]
[MP3 audio file. 5,399 kB.]
PAO: Velocity is 23,128 feet per second. Down range 1,000 miles, altitude 101 miles.
000:10:01 McCandless: Apollo 11, this is Houston. At 10 minutes, you are Go.
000:10:06 Armstrong: Ah, roger. 11's Go. [Long pause.]
PAO: Capcom Bruce McCandless giving the reports here from the Control Center.
000:10:24 McCandless: Apollo 11, this is Houston. Predicted cut-off at 11 plus 42. Over.
000:10:29 Armstrong: 11:42. Rog. [Long pause.]
PAO: Downrange 1,175 miles, velocity 24,190 mile - feet per second, altitude 102 nautical miles.
PAO: Apollo 11 still Go on all sources.
000:11:03 McCandless: Apollo 11, this is Houston. You are Go at 11.
000:11:08 Armstrong: That's a Go. [Long pause.]
PAO: We're predicting third stage shutdown at 11 minutes, 42 seconds. Velocity 25,254 feet per second. Downrange 1,400 miles now. Altitude 102.8 nautical miles.
000:11:42 Armstrong: Shutdown.
PAO: Shutdown right on time.
000:11:45 Collins: SECO. We are showing 101.4 by 103.6.
000:11:51 McCandless: Roger. Shutdown. We copy 101.4 by 103.6.
000:12:06 McCandless: Apollo 11, this is Houston. You are confirmed Go for orbit.
000:12:12 Armstrong: Roger. [Long pause.]
PAO: We show insert...
000:12:24 McCandless: Apollo 11, this is Houston. The booster is safe.
000:12:29 Armstrong: Ah, roger. [Long pause.]
PAO: We show velocity at insertion, 25,568 feet per second.
000:13:27 McCandless: Apollo 11, this is Houston. The booster has been configured for orbital coast. Both spacecraft are looking good. Over.
000:13:35 Armstrong: Roger. [Long pause.]
000:14:33 McCandless: Apollo 11, this is Houston. Vanguard LOS at 15:35. AOS Canaries at 16:30. Over.
000:14:43 Armstrong: Okay. Thank you.
[Comm break.]
PAO: This is Apollo Control. Based on a vector from the Instrument Unit of the third stage of the Saturn V, here on the ground we're showing an orbit of 102.5 by 99.7 nautical miles. The Flight Dynamics Officer Dave Reed wants to get some radar tracking to refine this orbit. He will report a refined orbit after more radar tracking.
(from) Left to right : Armstrong, Collins, Aldrin