The Saturn V Moon Rocket
Everybody at some time in their life has thrown an object into the air, and it always comes back down. If you throw it really hard it can go up a fair way, but gravity, although a fairly weak force is nevertheless quite hard to defeat if you want an object to leave the earth and not come back.
The boundary between earth's atmosphere and space is called the Karman line and its 100 km straight up or around 330,000 ft above sea level. You can not use a normal engine to get into space, as the higher you get, the thinner the atmosphere and eventually no oxygen to support combustion, if you want to leave earth you need a rocket as these carry the fuel they need plus the oxygen to burn it.
The Saturn V was 111 meters or 363 feet tall, about the same as a 36 story building and 18 meters taller than the Statue of Liberty, fully fueled it weighed 2.8 million kg. By comparison a fully loaded Boeing 747 is 1/10th of the weight while the even bigger Airbus A-380 has a maximum take off weight of 575 tonnes (575,000 kg).
So why the disparity in size, why did the Saturn V need to be so big? Well it had a huge job to do. To get a payload into low earth orbit you need to accelerate to 28,054 km/h at an altitude of 2,000 km or more.
The S1-C First Stage
Five Rocketdyne F1 engines powered the 5,100 tonne, 42m high and 10m diameter first stage, 94% of the weight being RP-1 fuel and liquid oxygen. Its job was to get the rocket off the ground. Nine seconds before liftoff the engines started and at full power produced a combined 7.6 million pounds of thrust.
In less than 3 minutes (168 seconds) all the fuel is gone but by then the rocket is traveling 8,300 km/h and is 67km above the earth and 93km down range due to the rotation of the earth after launch. Its job done, the first stage is discarded to fall into the pacific ocean.
The S-II second stage
The second stage was the same diameter but only 25m tall weighing in at 480,000kg, again mostly fuel (90% by weight). As the rocket is now quite a bit smaller the second stage only required five less powerful Rocketdyne J2 engines with a combined thrust of a mere 1.1 million pounds. The fuel this time was Liquid hydrogen but again using Liquid Oxygen as an oxidiser.
The second stage takes the rocket up to a near orbital speed of 25,000 km/h and an altitude of 176km in a further 384 seconds before the fuel is used up and the like the first stage it is discarded to burn up as it returns to earth.
The S-IVB third stage
The third stage at 18m tall and 6.6m diameter was the smallest. Weighing 119,000kg again mostly fuel its single F2 engine had to be run twice. The first 147 seconds boosted the speed to 28,054 km/h, a stable orbital speed, after one or two orbits and the completion of final checks it was then restarted to place the remaining 46,000Kg spacecraft with its three astronauts on a moon orbital trajectory with a further 347 second burn.
Its job then complete it was discarded, the third stage could not return to earth however as at the completion of the moon orbital trajectory burn is was already at escape velocity. The first few were put into a solar orbit with the last four deliberately crashed into the moon where seismographs placed by earlier moon missions registered the impacts. The third stage of Apollo 12 was located some years later and for a while thought to be an asteroid until images revealed its actual identity.
The boundary between earth's atmosphere and space is called the Karman line and its 100 km straight up or around 330,000 ft above sea level. You can not use a normal engine to get into space, as the higher you get, the thinner the atmosphere and eventually no oxygen to support combustion, if you want to leave earth you need a rocket as these carry the fuel they need plus the oxygen to burn it.
The Saturn V was 111 meters or 363 feet tall, about the same as a 36 story building and 18 meters taller than the Statue of Liberty, fully fueled it weighed 2.8 million kg. By comparison a fully loaded Boeing 747 is 1/10th of the weight while the even bigger Airbus A-380 has a maximum take off weight of 575 tonnes (575,000 kg).
So why the disparity in size, why did the Saturn V need to be so big? Well it had a huge job to do. To get a payload into low earth orbit you need to accelerate to 28,054 km/h at an altitude of 2,000 km or more.
The S1-C First Stage
Five Rocketdyne F1 engines powered the 5,100 tonne, 42m high and 10m diameter first stage, 94% of the weight being RP-1 fuel and liquid oxygen. Its job was to get the rocket off the ground. Nine seconds before liftoff the engines started and at full power produced a combined 7.6 million pounds of thrust.
In less than 3 minutes (168 seconds) all the fuel is gone but by then the rocket is traveling 8,300 km/h and is 67km above the earth and 93km down range due to the rotation of the earth after launch. Its job done, the first stage is discarded to fall into the pacific ocean.
The S-II second stage
The second stage was the same diameter but only 25m tall weighing in at 480,000kg, again mostly fuel (90% by weight). As the rocket is now quite a bit smaller the second stage only required five less powerful Rocketdyne J2 engines with a combined thrust of a mere 1.1 million pounds. The fuel this time was Liquid hydrogen but again using Liquid Oxygen as an oxidiser.
The second stage takes the rocket up to a near orbital speed of 25,000 km/h and an altitude of 176km in a further 384 seconds before the fuel is used up and the like the first stage it is discarded to burn up as it returns to earth.
The S-IVB third stage
The third stage at 18m tall and 6.6m diameter was the smallest. Weighing 119,000kg again mostly fuel its single F2 engine had to be run twice. The first 147 seconds boosted the speed to 28,054 km/h, a stable orbital speed, after one or two orbits and the completion of final checks it was then restarted to place the remaining 46,000Kg spacecraft with its three astronauts on a moon orbital trajectory with a further 347 second burn.
Its job then complete it was discarded, the third stage could not return to earth however as at the completion of the moon orbital trajectory burn is was already at escape velocity. The first few were put into a solar orbit with the last four deliberately crashed into the moon where seismographs placed by earlier moon missions registered the impacts. The third stage of Apollo 12 was located some years later and for a while thought to be an asteroid until images revealed its actual identity.
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