Rockets.


 

Newton's third law states that, "For every action, there is an equal and opposite reaction.".

A bird pushes its wings against the air. A fish pushes its fins against the water. A gun recoils against the expelled bullet and it's propellent gas.

Rockets are unique, in that in the vacuum of space, they have nothing to react against except the jet of high speed gas blasting from the tail. For that, they carry fuel and an oxidizer (usually liquid oxygen).

Early Chinese Rockets.

 



 

It was the Chinese who invented gunpowder, and after that, rockets.

Rocket technology first became known to Europeans following their use by the Mongols - Genghis Khan and Ögedei Khan, when they conquered parts of Russia, Eastern, and Central Europe. . .

The Mongols in turn had acquired the Chinese technology by conquest of the northern part of China and also by the subsequent employment of Chinese rocketry experts as mercenaries for the Mongol military. .

The Battle of Sejo in the year 1241 describes the use of rocket-like weapons by the Mongols against the Magyars.

German V2 Rocket.

   
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It was in Germany during WWII, when a team led by Wernher von Braun constructed the first successful liquid fueled rocket.
It was the V2, and the tailfins and engine are shown here. Liquid oxygen and kerosene are pumped into the engine.
To stop the engine melting, the cold oxygen passed through pipes in its walls, becoming a gas before being fed into the combustion chamber and ignited.

Below the engine are thin fins of carbon which steered the rocket. This was around 1942.

They were launched high across the English channel, and aimed at London. Carrying one ton of explosive, they travelled faster than sound, so could not be heard coming.

 

Russian Vostok Rocket.

   
 

The Vostok 3KA spacecraft was launched on April 12, 1961. The flight made Yuri Gagarin, a cosmonaut from the Soviet Union, not only the first man into space, but also the first to orbit the earth.

The four outside cylinders drop off after they have exhausted their fuel. This means the main central rocket now has a much smaller load to lift

Soyuz Space Rocket.

   

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Whilst the German V2 rocket had one engine, this Soyuz has 20 main engines for thrust.

In addition, there are 12 small "vernier" engines for steering.. These all have to ignite together.

 

 

Preparing Soyuz for Launch.

 

 

 

After forty years of development, in 2000, this Russian Soyuz space rocket is being transported on a special train to its launching pad, where it will launch the first live-in crew to the International Space Station. The large wide section at the top will carry the 3 man crew.

The thin section above that, is a small solid fuel rocket, and some of the rocket nozzles can be seen pointing outwards.
Should the huge main rocket fail on the launching pad, then this small one fires and drags the crew compartment away from danger, and high enough for a parachute to open.

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The huge, but empty rocket has now been moved from a horizontal position, to the vertical. The gantry arms are being swung up to the vertical.

The launch crew and the flight crew now have access to the various levels, and they can begin filling the tanks with liquid kerosene and liquid oxygen.
At launch, these two components are pumped into the rocket engines, where they ignite and provide enormous thrust, lifting the rocket off the ground.

 

Design Differences - American-Russian.

 

 

The Russians have their stages beside the main rocket, unlike the Americans who stack them one above the other.

American Apollo Moon Rocket.

   
 

This rocket in one of the American Apollo series which went to the moon. It also has fuel tanks holding liquid oxygen, and a fuel. It stands 363ft (110.6m) tall, each stage mounted one on top of the other.

Above the conical crew compartment can be seen the "escape tower", the same type as that used on the Russian Soyuz. Once the Apollo rocket had launched to a safe height, small bolts would explode and the escape tower fired away.

The 3 man crew compartment was the only part of this rocket which returned to earth. It had to be turned so that its blunt base faced the earth. It needed to enter the atmosphere at a shallow angle. If that angle was too steep the module would burn up. If too gradual, the module would skip off into space, like a flat stone off water.

Once through the atmosphere, a small "drogue" parachute would open first, then 3 huge parachutes would lower it in the sea.

American Moon Landing.

 

 

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The Apollo rocket carried this "Lunar Landing Module".When it was launched from earth, it was concealed within the rocket's streamlined body, and so is not visible in the above view.

A small vehicle it carried a crew of two, and landed on the moon. Because there is no atmosphere, there is no need for it to be a streamlined shape.
A single rocket engine pointing straight down provided all the lift. If it failed, it could not glide, even a parachute would be useless.

On the first moon landing Neil Armstrong and Buzz Aldren had only 30 seconds of fuel left, when they finally touched down.

This later mission was able to carry a vehicle.

 
When leaving the moon, the lower part stayed on the moon, acting as a launch pad while the top section, now with a smaller load, carried the crew back up into a lunar orbit about 60 miles above the moon.
There, they met up with the third crewman Richard Collins who had been waiting in orbit.
As moon gravity is only 1/6 that of Earth, then a small rocket can be used for this particular launch.

The Space Shuttle.

   

 

Although the Apollo moon missions were successful, they were very expensive, one reason being that non of the parts survived to be re-used. So the Americans designed a vehicle which could carry large heavy loads into space, and they hoped, be re-usable.
This was the space shuttle.

The huge white section is not a rocket, it is simply an enormous tank, 47 metres high, divided into two compartments. It holds 2 million litres.
The top holds liquid oxygen, and a yellow pipe can be seen which feeds it into the base of the shuttle to drive three rocket engines. Liquid hydrogen in the base of the tank also feeds those engines.

Because these liquids are extremely cold, the tank is coated with an insulating layer of foam. Otherwise the liquids would boil off, and ice condense on the outside, adding to the load.

     

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On either side of the fuel tank are two solid fuel rockets.

These are 45.5 metres tall, and contain a mixture of aluminium powder and iron oxide.

When launched, the solid rocket boosters (SRB's) last for only 2 minutes. At a height of 45kms (28 miles) they are released, lightening the load remaining. Parachutes deploy, lowering the empty rockets to the ocean for recovery and re-use.

After 8 minutes, the shuttle has reached about 109kms (68 miles). The tank is released. This tank is not re-usable. After its release, it falls back and is burnt up in the atmosphere.

 

In Orbit.

   
 

When it is in earth orbit, the shuttle is travelling at around 16,000 mph. It uses its two low powered orbital manoeuvring engines ( inside the two white bulges at the rear) to reach its final orbit.

Depending on the mission, this may be between 115 and 690 miles above the earth.

It is then turned to face backwards, the cargo doors can be opened, and the astronauts float outside and release the cargo.


For the descent, the engines fire and the speed drops, so that the shuttle begins to fall towards the earth.

It turns again, and facing forward enters the atmosphere. The air friction slows the shuttle, but generates temperatures up to 1,430'C (2,606'F).

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Unlike earlier manned space vehicles, the shuttle can lower it's wheels and land on a runway.

The black areas of the shuttle heat the most, and special tiles are needed to avoid the shuttle melting.

The crew do not have to endure dangerous stresses, as in rocket launches. At launch it's only 3g. At re-entry 1.5g.



The shuttle proved to be far more expensive than hoped. Two shuttles have been destroyed, killing both crews. The design has been abandoned.
Americans can now only venture into space on board Russian rockets.
 
 

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