Undoubtedly the crowning engineering achievement of the Apollo space program was the mighty Saturn V rocket, which stood 363 feet tall, weighed nearly 33,500 tons, and was capable of rocketing a payload of 130 tons out of Earth orbit and on its way to the Moon. To date, the Saturn V is both the largest and most powerful rocket, as well as the most powerful machine ever built by mankind, delivering a mind-boggling 7.8 million pounds of lift-off thrust.
The Saturn V project was supervised by Dr. Werner Von Braun, the controversial German scientist who developed the V2 ICBM before being smuggled to America at the end of World War II. Von Braun brought enough spare components with him to build several functioning V2 rockets for the US Army during the 1950’s. Nearly all of the rockets and missiles developed by the United States during the 1950’s and 1960’s were in some way based on Dr. Von Braun’s designs. His cooperation and leadership were essential to the development of American rocketry, and it can be argued that he truly was the “secret weapon” that allowed us to defeat the Soviets during the “Space Race.”
A rocket works by ejecting a tremendous amount of mass in a controlled, direction-dependent flow. Newton’s third law (action and reaction) ensures that such an ejection will create momentum in the opposite direction. The fuel is burned because combustion increases the expansion of the rocket fuel as it exits the rocket, which in turn increases its velocity and therefore greatly improves the rocket’s thrust.
The main problem with building large rockets involves the weight of the rocket fuel. The bigger the rocket, the more fuel must be expended in order for the rocket to fly. This in turn means that essentially most of the payload for a large rocket will be its own fuel. Von Braun’s team solved this problem by creating multi-stage rockets. In a multi-stage rocket, the first stage contains the most powerful engines and the most fuel, because the first stage must lift not only itself, but also the upper stages of the rocket and the payload. But when the first stage’s fuel is spent, the first stage can be separated, leaving a much lighter rocket in flight. Consequently, the rocket engines of the upper stages do not need to be nearly as powerful, which saves considerable weight both in mechanical components and fuel.
Another problem encountered by rockets is vibration. Vibration, especially if it is amplified by the structure of the rocket and becomes mechanical resonance, can be incredibly destructive, compromising structural integrity and tearing rocket engines, pumps, and fuel lines apart. Large rockets are particularly susceptible to “pogo oscillation,” so named because during pogo the fuel in the rocket begins sloshing up and down, subjecting the rocket to an effect similar to being bounced up and down on a pogo stick.
Von Braun and his team of engineers developed elegant solutions to virtually all of these problems. The Saturn V consisted of three stages: S-IC, powered by five enormous F-1 engines that together consumed 1350 gallons of kerosene and 2000 gallons of liquid oxygen per second, burning its 2200 tons of fuel in two and a half minutes; S-II, powered by five much smaller J-2 engines burning liquid hydrogen (much lighter than kerosene) and liquid oxygen, and S-IVB, powered by one J-2 engine and carrying the payload (the lunar module and the command/service module). Because of the velocity achieved by the S-IB and S-II stages, combined with the loss of their mass during separation, the S-IVB stage was capable of pushing itself and its payload out of Earth orbit and on a course for the moon. The Saturn V vehicle was also revolutionary in that it housed all of its monitoring, computing, and telemetry circuitry in two inter-stage rings between the first and second, and the second and third stages.
The five F-1 engines in the S-IC first stage included a gimbal support that allowed the thrust of the engines to be redirected during flight, thus giving the Saturn V a superior steering capability. And because the Saturn V’s stages contained no more than five engines, engineers were able to solve mechanical problems with relative ease, including a revolutionary technique of injecting hydrogen into the fuel mixture via the main fuel pumps as a way to dampen vibrations and eliminate pogo. The Soviet N-1 booster, developed to carry their cosmonauts to the moon, contained thirty rocket engines in its first stage, and suffered from serious mechanical problems that Soviet engineers could never solve. All four N-1 launch attempts by the Soviets ended with the destruction of the rocket before it reached the upper atmosphere.
In all thirteen Saturn V rockets were launched: Apollo 4 and 6 were unmanned test flights; Apollo 8 – 17 were manned flights with only Apollo 9 remaining in Earth orbit (that mission tested the docking and flight capabilities of the lunar module). The final Saturn V launch blasted the Skylab station into space. Components for three additional Saturn V rockets were manufactured, and today those components exist as museum displays at the NASA space centers in Houston, Huntsville, Alabama, and Cape Kennedy.
The Los Angeles Times has a good write-up about the development of the Saturn V, including interviews with many of the engineers who designed the rocket.
Here is a NASA film of the launch of the Apollo 11 Saturn V. The film begins as the rocket fuel (kerosene and liquid oxygen) begins streaming out of the engine nozzles (3350 gallons per second) and is ignited by an outboard system that resembles a 4th of July sparkler. (You can see these igniters burn very clearly underneath the Space Shuttle during a Shuttle launch). We also get good views of the numerous mechanical clamps and arms swinging away as the rocket begins to ascend. The ice forms on the rocket as the pumps begin to deplete the liquid fuel in the tanks and the outside of the rocket plunges in temperature (the same effect that causes an aerosol can to grow cold when its contents are released). Vibrations from the rocket cause the ice to fall off in huge sheets. By the way, if anyone knows how the filming inside the service tower and under the launch pad was accomplished without the film being destroyed by intense heat, I would be interested in hearing about it.
Incidentally, in what must be a major blow to conspiracy theorists everywhere (well, not really – they’ll probably just claim the photos are fakes) the Lunar Reconnaissance Orbiter has just photographed several Apollo mission landing sites, and its images clearly show the lunar module descent stages, scientific instruments, and foot paths left behind by our astronauts.