Saturn V

This article is about the rocket. Saturn V may also refer to the numerical designation of Rhea, the moon of Saturn.

Saturn V

The first Saturn V, AS-501, before the launch of Apollo 4
Fact sheet
Size
Height	111 m (364 ft)
Diameter	10 m (33 ft)
Mass	2,800,000 kg (6,300,000 lb)
Stages	3 (2 for Skylab launch)
Capacity
Payload to LEO	127,000 kg (3-stage) 75,000 kg (2-stage)
Payload to the Moon	47,000 kg
First Stage - S-IC
Engines	5 F-1 engines
Thrust	33.4 MN (7,500,000 lb)
Burn time	150 s
Fuel	RP-1 and liquid oxygen
Second Stage - S-II
Engines	5 J-2 engines
Thrust	5 MN (1,000,000 lb)
Burn time	360 s
Fuel	Liquid hydrogen and liquid oxygen
Third Stage - S-IVB
Engines	1 J-2 engine
Thrust	1 MN (225,000 lb)
Burn time	165 + 335 s (2 burns)
Fuel	Liquid hydrogen and liquid oxygen

The Saturn V (popularly known as the Moon Rocket) was a multistage liquid-fuel expendable rocket used by NASA's Apollo and Skylab programs. It was the physically largest production (but not designed) model of the Saturn family of rockets designed under the direction of Wernher von Braun and Arthur Rudolph.

A total of 13 Saturn V rockets were launched from 1967 to 1973, with a perfect launch record. The main payloads of the rocket were the Apollo spacecraft which carried the NASA astronauts to the Moon. It also launched the Skylab space station.

Background

In the early 1960s the Soviet Union had beaten the United States in many firsts of space flight; most importantly the launch of the first artificial satellite Sputnik 1 in 1957, and Yuri Gagarin's first manned flight in 1961. The next major goal, and an achievement which would be rewarded with space leadership in the eyes of the world, was a manned Moon landing. Saturn V was the launch vehicle USA chose to turn the tide of the space race.

In 1961, when President Kennedy announced that America would try to get to the Moon by the end of the decade, there was nothing in the arsenal of the United States (or in fact anywhere in the world) that could launch a manned spacecraft to the Moon in one piece. The Saturn I was in development but had not yet flown and, due to its small size, would require several launches to place in orbit all the components of a lunar spacecraft.

On January 10, 1962, NASA announced plans to build the Saturn V, though at that point it was called the Saturn C-5. In 1963, the first engines were produced. They were qualified for manned flight in October 1966. After intensive design and testing of several years, the rocket was first launched on November 9, 1967 with the Apollo 4 unmanned spacecraft on board.

Technology

The Saturn V is arguably one of the most impressive machines in human history. Over 110 m high and 10 m in diameter, with a total mass of three thousand metric tonnes and a payload capacity of 118,000 kg to LEO, the Saturn V dwarfed and overpowered all other rockets which have ever successfully flown, with the exception of the Soviet Energia booster.

Saturn V was designed by the Marshall Space Flight Center in Huntsville, Alabama. It used the new powerful F-1 and J-2 rocket engines for propulsion. Designers decided early on to attempt to use as much technology from the Saturn I program as possible. As such the S-IVB third stage of the Saturn V was based on the S-IV second stage of the Saturn I. The instrument unit that controlled the Saturn V shared characteristics with that carried by the Saturn I.

Stages

Saturn V consisted of three separate stages and the instrument unit, which were developed by various contractors of NASA.

• The S-IC first stage was built by The Boeing Company. As with almost every rocket stage, most of its mass of over two thousand metric tonnes at launch was fuel, in this case RP-1 rocket fuel and liquid oxygen oxidiser. It was 42 meters tall and 10 meters in diameter, and provided 33.4 MN of thrust to get the rocket through the first 61 kilometers of ascent. The five F-1 engines were arranged in a cross pattern. The center engine was fixed, while the four on the outer ring could be hydraulically turned to control the rocket.

• The S-II second stage was built by North American Aviation. Using liquid hydrogen and liquid oxygen it had five J-2 engines in a similar arrangement to the S-IC. The second stage accelerated the Saturn V through the upper atmosphere with 5 MN of thrust.

• The S-IVB third stage was built by the Douglas Aircraft Company. It had one J-2 engine and was used twice during the mission: first for the orbit insertion after second stage cutoff, and then for the trans lunar injection (TLI) when the timing was right. It was not necessary for low earth orbit launches. This stage was also used as the second stage of the Saturn IB.

• The instrument unit, built by IBM, rode atop the third stage. It included guidance and telemetry systems for the rocket.

All three stages also used small solid-fuelled ullage motors that helped to separate the stages during the launch, and to ensure that the liquid propellants were in a proper position to be drawn into the pumps.

In the event of an abort requiring the destruction of the rocket, the range safety officer would send the signal for shaped explosive charges attached to its outer surfaces of the rocket to detonate. These would make cuts in fuel and oxidiser tanks to disperse the fuel quickly and to minimise mixing. After the Launch Escape Tower had been jettisoned the charges were safed.

Comparisons

The F-1 engines of the S-IC first stage engines dwarf their creator, Wernher von Braun.

The Soviet counterpart of the Saturn V was the N-1 rocket. It was even bigger than the Saturn V, but never made it even to first stage separation successfully. The decision to use five very powerful engines for the first stage of Saturn V resulted in a much more reliable configuration than the 30 smaller engines of the N-1. During several launches, the Saturn V was even able to recover from the loss of engines.

A few newer rockets have been able to successfully challenge the records set by Saturn V.

• The Soviet Energia was 46 MN heavy-lift booster to deliver up to 120-150 metric tonnes to LEO in the Vulkan configuration. It never flew at this capacity, and it was only launched twice.
• The Space Shuttle generates a peak thrust of 34.8 MN, although payload capacity to LEO (excl. Shuttle Orbiter itself) is only 28,800 kg.

Currently the most powerful expendable launch system of the U.S. is the Titan IV with a thrust of approximately 17 MN, with a lift capacity of 21,700 kg to LEO and 5,800 kg to geosynchronous transfer orbit (GTO) (thus being much weaker than the Saturn V). The European Ariane 5 performs slightly better with the newest versions delivering up to 10 metric tonnes to geosynchronous orbit.

Five giant F-1 engines hefted the Saturn V from a stop to near orbital speeds each providing 1.5 million pounds (6.7 million newtons) of thrust.

Lunar mission launch sequence

Saturn V carried the Apollo astronauts to the Moon. All Saturn V missions were launched from Launch Complex 39 at the John F. Kennedy Space Center. Mission control was transferred to the Johnson Space Center in Houston, Texas after the rocket cleared the launch tower.

These parts of the conversation between the mission control and the astronauts of the Apollo 13 mission demonstrate the details of the timing of the launches as well as the capabilities of the Saturn V.

S-IC sequence

The first stage burned for 2.5 minutes lifting the rocket to 61 kilometers and to a speed of 8600 km/h. In the process it used 2,000,000 kg of propellant.

• -00:00:08 "...eight, ignition sequence has started, six, five, four, three..."

The first stage ignition sequence involved having the center engine ignite first, followed by opposing outboard pairs at 300-millisecond stagger times, so as to reduce the structural loads on the rocket.

• 00:00:00 "...zero, we have commit, and we have liftoff at two-thirteen (EST)."

When full thrust had been confirmed by the onboard computers, the rocket was 'soft-released'. This was done in two stages: first, the hold-down arms were released, and as the rocket began to accelerate upwards, it was held back somewhat by tapered metal pins being pulled through holes. This lasted for half a second. Once the rocket had lifted off it could not safely settle back down onto the pad if the engines failed.

• 00:00:06 "The Saturn-V building up to seven point six million pounds of thrust, and it has cleared the tower."

As it moved past the tower, the rocket could be seen to noticably yaw away from the tower. This was to ensure adequate clearance. At an altitude of 130 meters the rocket began to roll and then pitch to the correct flight azimuth. This part of the flight is pre-programmed.

• 00:00:25 "Flight Dynamics Officer (FIDO) says the trajectory looks good. We show one-half mile in altitude at this time."
• 00:00:46 "Altitude one point two miles, velocity fifteen-hundred feet per second."
• 00:01:10 "And at one minute, ten seconds we show an altitude of four point one nautical miles, downrange one mile."
• 00:01:37 "And the booster engineer reports we're now through the region of maximum dynamic pressure. We're go."

A visible shockwave formed as the Apollo 11 Saturn V encountered Maximum Dynamic Pressure (Max Q) at about 1 minute 20 seconds into the flight (altitude 12.5 km, 4 km downrange, velocity 1,600 km/h).

• 00:02:15 "Inboard."

At 135.5 seconds the center engine shut down. This was again to reduce the structural load on the rocket, as opposed to having all the engines shutting down at once. The crew also experienced their greatest acceleration during the launch phase just before first stage cut off with 4 g

• 00:02:36 "Coming up on thirty miles altitude."

The other engines continued to burn until either the oxidiser or fuel was depleted as measured by sensors in the suction assemblies. 600 milliseconds after the engine cutoff the first stage separated with the help of the eight solid-retrorockets. This occured at an altitude of about 62 km. The first stage continued to an altitude of 110 km. It impacted in the Atlantic Ocean about 560 km from the launch pad.

• 00:02:44 "Staging."

S-II sequence

The second stage then burned for 6 minutes to propel the craft to 185 km and 24,600 km/h, nearly at orbital velocity. Apollo 13 had a problem with a premature shutdown of the center engine of the S-II. This had little effect on the mission but the second stage was used for about 10 seconds longer than planned to compensate. See Apollo abort modes for more information about the various abort modes that could have been used during a launch.

• 00:02:50 "S-II ignition."

The second stage had a two-part ignition process. Firstly, eight solid-fuel rockets ignited for four seconds to give positive acceleration, then the five J-2 engines ignited.

• 00:03:00 "13, Houston. Trajectory's good, thrust is good."
• 00:03:20 "We confirm skirt sep (separation). Roger, tower jett. Mode two, Jim. Looking good."

Still from footage of Apollo 6's interstage falling away (NASA)

The second part of the ignition was that about 30 seconds after the first stage separated, the aft interstage separates from the second stage. This was a precisely controlled manouver as the interstage must not touch the engines and only had a clearance of one meter.

At the same time as the interstage separated, Launch Escape System was jettisoned.

• 00:05:30 "And at five minutes, thirty seconds into the launch, we continue to look very good on the second stage. Jim Lovell just reported the inboard engine has shut down as scheduled."

As with the first stage, the center engine was shut down early to reduce structual loads.

• 00:09:15 "Our predicted shutdown time on the second stage is 9 minutes, 48 seconds, Flight Director Milton (L.) Windler (Maroon Team) getting a staging status now from his flight controllers."

Due to the premature loss of the center engine, the Instrument Unit had to compensate by burning the other four engines longer than usual. It should be noted that this early shut off had nothing to do with the later problems that Apollo 13 experienced.

• 00:09:49 "Staging."

There were five sensors in the bottom of each tank of the S-II. When two of these were uncovered, the Instrument Unit would intiate the staging sequence. One second after the second stage cut off it separated and a tenth of a second later the third stage ignited. The S-II impacted about 4200 km from the launch site.

S-IVB sequence

The third stage burned for a further 2.5 minutes, about 12 minutes after launch. The third stage remained attached while the spacecraft orbited the Earth two and a half times in a 'parking orbit' while astronauts examined the spacecraft and rocket to make sure everything functioned nominally.

• 00:09:51 "And S-IV ignition."

Unlike with the previous separation, there was no two-stage separation. The interstage between the second and third stages remained attached to the second stage.

• 00:10:32 "At ten minutes thirty seconds we are now one-hundred two in altitude, one-thousand eighty miles downrange."
• 00:13:08 "Apollo thirteen, Houston. You have a go orbit, all sources and the booster is safe. Over."
• 00:15:05 "Apollo 13, Houston. You're preliminary orbit down here is one-hundred two point five times one-hundred point three and everything is looking good."

The spacecraft was now in an orbit of about 180 km by 165 km. This is quite low by Earth orbit standards and would not have remained stable for very long due to interaction between the spacecraft and the Earth's atmosphere. The next two and a half orbits were spent checking out the systems of the spacecraft and preparing the spacecraft for Trans Lunar Injection (TLI).

• 02:35:44 "Ignition, Houston."

The S-IVB stage from the Apollo 7 flight in Earth orbit. Although Apollo 7 used a Saturn IB booster, the S-IVB stage was used on both the Saturn IB and Saturn V

• 02:41:40 "It's off. Engine off."

A couple of hours after TLI the Apollo Command Service Module (CSM) separated from the third stage, turned 180 degrees, and docked with the Lunar Module (LM) which rode below the CSM during launch. The CSM and LM then separated from the third stage.

If it was to remain on the same trajectory as the spacecraft, the booster could have presented a hazard later in the mission, so the remaining propellant in its tanks vented out of the engine, changing its trajectory. Controllers targeted the third stage either into a solar orbit or, as in the case of the third stages from Apollo 13 onwards, directed it to impact the Moon. Seismometers left behind by previous missions detected the impacts, and the information helped map the inside of the Moon.

Later use of Saturn V systems

The last Saturn V launch carried the Skylab space station to low Earth orbit in place of the third stage.

Apart from manned lunar flights, the Saturn V launched the Skylab space station into Earth orbit. Skylab replaced the third stage of the Saturn V and, as such, this last flown Saturn V had only two live stages.

The Space Shuttle was initially conceived of as a cargo transport to be used in concert with the Saturn V. The Shuttle would handle space station logistics, while Saturn V would launch components. Lack of funding for a second Saturn V production run killed this plan and left the United States without a heavy-lift booster for the next 30 years (and counting). Some in the U.S. space community have come to lament this situation, as continued production would have allowed the International Space Station to have been lofted with just a handful of launches.

Wernher von Braun and others also had plans for a rocket that would have featured eight F-1 engines in its first stage allowing it to launch a manned spacecraft on a direct ascent flight to the Moon. Other plans for the Saturn V called for using a Centaur as an upper stage or adding strap-on boosters. These enhancements would have increased its ability to send large unmanned spacecraft to the outer planets or manned spacecraft to Mars. The second production run of Saturn Vs (had it happened) would very likely have used the F-1A engine in its first stage, providing a substantial performance boost over the first run. Other likely changes would have been the removal of the fins, since they turned out to provide little benefit when compaired to their weight; a stretched S-IC first stage to support the more powerful F-1As; and uprated J-2s for the upper stages. Saturn V was also to be the launch vehicle for the nuclear rocket stage RIFT test program and the later NERVA. U.S. proposals for a rocket larger than the Saturn V from the late 1950s through the early 1980s were generally called Nova. Over thirty different large rocket proposals carried the Nova name.

Saturn V vehicles and launches

The Saturn V launched day or night in foul weather or fair at the appropriate time to reach its destination as shown in this montage of all launches.

Currently there are three Saturn Vs on display, all lying on the ground:

• At the Johnson Space Center made up of first stage of SA-514, the second stage from SA-515 and the third stage from SA-513.
• At the Kennedy Space Center made up of S-IC-T (test stage) and the second and third stages from SA-514.
• At the U.S. Space & Rocket Center, Huntsville, Alabama made up of S-IC-D, S-II-F/D and S-IVB-D (all test stages not meant for actual flight).

Of these three, only the one at the Johnson Space Center consists only of stages that were meant to be launched. The US Space & Rocket Center also has on display an erect full scale model of the Saturn V. The first stage from SA-515 resides at the Michoud Assembly Facility, New Orleans, Louisiana.

A popular, untrue (http://www.space.com/news/spacehistory/saturn_five_000313.html) urban legend, started in 1996, states that NASA has lost or destroyed the blueprints or other plans for the Saturn V. In fact, the plans still exist on microfilm at the Marshall Space Flight Center, though it seems unlikely that future engineers will find that the plans will come in handy after the subsequent 40-plus years of advances in rocket science.

References

• Bilstein, Roger E. (1980). Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles. NASA SP-4206. ISBN 0-16-048909-1.
  • Available for reading on-line: http://history.nasa.gov/SP-4206/sp4206.htm
  • and in softcover through the U.S. Government Printing Office: http://history.nasa.gov/gpo/order.html
• Apollo Saturn Reference Page (http://www.apollosaturn.com)
• Apollo Lunar Surface Journal (http://www.hq.nasa.gov/alsj/)
• Stages to Saturn: A Technological History of the Apollo/Saturn Launch Vehicles. NASA SP-4206 (PDF format) (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19970009949_1997011911.pdf)
• Saturn illustrated chronology: Saturn's first eleven years, April 1957 - April 1968 (PDF format) (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19740004382_1974004382.pdf)
• Moonport: A history of Apollo launch facilities and operations (http://www.hq.nasa.gov/office/pao/History/SP-4204/cover.html)
• Saturn 5 launch vehicle flight evaluation report: AS-501 Apollo 4 mission (PDF format) (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900066482_1990066482.pdf)
• Saturn 5 launch vehicle flight evaluation report: AS-508 Apollo 13 mission (PDF format) (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900066486_1990066486.pdf)
• Saturn V Flight Manual - SA-503 (PDF format) (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750063889_1975063889.pdf)
• Saturn V Press Kit (http://history.msfc.nasa.gov/saturnV/)
• Excerpts from the Apollo 13 Transcript (http://myweb.accessus.net/~090/as13.html)

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