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Sunday, July 24, 2011

Modern rocketry

Modern rocketry was the rocket progress after World War 1, World War 2, post war, Cold war and current. It all started when Robert Goddard fired the world's first liquid-fuel rocket in Auburn, Massachusetts. In this page, more information is given on modern rocketry.





Modern rocketry

Pre–World War II


Robert Goddard and the first liquid-fueled rocket.
Modern rockets were born when Goddard attached a supersonic (de Laval) nozzle to a liquid-fueled rocket engine's combustion chamber. These nozzles turn the hot gas from the combustion chamber into a cooler, hypersonic, highly directed jet of gas, more than doubling the thrust and raising the engine efficiency from 2% to 64%. In 1926, Robert Goddard launched the world's first liquid-fueled rocket in Auburn, Massachusetts.
During the 1920s, a number of rocket research organizations appeared worldwide. In 1927 the German car manufacturer Opel began to research rocket vehicles together with Mark Valier and the solid-fuel rocket builder Friedrich Wilhelm Sander. In 1928, Fritz von Opel drove with a rocket car, the Opel-RAK.1 on the Opel raceway in Rüsselsheim, Germany. In 1928 the Lippisch Ente flew, rocket power was used to launch the manned glider, although it was destroyed on its second flight. In 1929 von Opel started at the Frankfurt-Rebstock airport with the Opel-Sander RAK 1-airplane, which was damaged beyond repair during a hard landing after its first flight.
In the mid-1920s, German scientists had begun experimenting with rockets which used liquid propellants capable of reaching relatively high altitudes and distances. In 1927 and also in Germany, a team of amateur rocket engineers had formed the Verein für Raumschiffahrt (German Rocket Society, or VfR), and in 1931 launched a liquid propellant rocket (using oxygen and gasoline).
From 1931 to 1937 in Russia, extensive scientific work on rocket engine design occurred in Leningrad at the Gas Dynamics Laboratory there. Well-funded and staffed, over 100 experimental engines were built under the direction of Valentin Glushko. The work included regenerative cooling, hypergolic propellant ignition, and fuel injector designs that included swirling and bi-propellant mixing injectors. However, the work was curtailed by Glushko's arrest during Stalinist purges in 1938. Similar work was also done by the Austrian professor Eugen Sänger who worked on rocket-powered spaceplanes such as Silbervogel. 
On November 12, 1932 at a farm in Stockton NJ, the American Interplanetary Society's attempt to static fire their first rocket (based on German Rocket Society designs) failed in a fire.
In 1930s, the Reichswehr (which in 1935 became the Wehrmacht) began to take an interest in rocketry. Artillery restrictions imposed by the Treaty of Versailles limited Germany's access to long distance weaponry. Seeing the possibility of using rockets as long-range artillery fire, the Wehrmacht initially funded the VfR team, but because their focus was strictly scientific, created its own research team. At the behest of military leaders, Wernher von Braun, at the time a young aspiring rocket scientist, joined the military (followed by two former VfR members) and developed long-range weapons for use in World War II by Nazi Germany.

World War II


A German V-2 rocket on a Meillerwagen

Layout of a V2 rocket
In 1943, production of the V-2 rocket began in Germany. It had an operational range of 300 km (190 mi) and carried a 1,000 kg (2,200 lb) warhead, with an amatol explosive charge. It normally achieved an operational maximum altitude of around 90 km (56 mi), but could achieve 206 km (128 mi) if launched vertically. The vehicle was similar to most modern rockets, with turbopumps, inertial guidance and many other features. Thousands were fired at various Allied nations, mainly Belgium, as well as England and France. While they could not be intercepted, their guidance system design and single conventional warhead meant that it was insufficiently accurate against military targets. A total of 2,754 people in England were killed, and 6,523 were wounded before the launch campaign was ended. There were also 20,000 deaths of slave labour during the construction of V-2s. While it did not significantly affect the course of the war, the V-2 provided a lethal demonstration of the potential for guided rockets as weapons.
In parallel with the guided missile programme in Nazi Germany, rockets were also used on aircraft, either for assisting horizontal take-off (JATO), vertical take-off (Bachem Ba 349 "Natter") or for powering them (Me 163, etc.). During the war Germany also developed several guided and unguided air-to-air, ground-to-air and ground-to-ground missiles. Here is a list of World War II guided missiles of Germany:

List of missiles

Surface-to-Surface missiles

The V-1 cruise missile was used operationally against London and Antwerp. The V-2 ballistic missile was used operationally against London, Antwerp, and other targets. The Rheinbote was fired against Antwerp.
  • V-1 flying bomb
  • V-2 rocket
  • Rheinbote
  • A4b
  • Ruhrstahl X-7 (Rotkäppchen) Guided anti-tank missile.

Surface-to-Air missiles

Germany developed a number of surface-to-air missile systems, none of which were used operationally:
  • Enzian (Gentian)
  • Rheintochter (Rhine Daughter) (an air-to-air variant was also planned)
  • Schmetterling (Butterfly) (an air-to-air variant was also planned)
  • Wasserfall (Waterfall)
  • Feuerlilie (Fire Lily)

Air-to-Air missiles

  • R4M rocket (unguided air-to-air rocket)
  • Werfer-Granate 21 (unguided air-to-air variant of the Nebelwerfer rockets)
  • Ruhrstahl X-4 (guided; anti-tank variants of this were also designed, such as the X-7 and X-10)

Anti-ship missiles

Anti-ship missiles were used operationally against allied shipping in 1943, notably in the Mediterranean Sea:
  • Fritz X anti-ship missile
  • Henschel Hs 293 air-to-ship gliding guided bomb


The Allies rocket programs were much less sophisticated, relying mostly on unguided missiles like the Soviet Katyusha rocket.

Post World War II


Dornberger and Von Braun after being captured by the Allies
At the end of World War II, competing Russian, British, and US military and scientific crews raced to capture technology and trained personnel from the German rocket program at Peenemünde. Russia and Britain had some success, but the United States benefited the most. The US captured a large number of German rocket scientists (many of whom were members of the Nazi Party, including von Braun) and brought them to the United States as part of Operation Overcast. In America, the same rockets that were designed to rain down on Britain were used instead by scientists as research vehicles for developing the new technology further. The V-2 evolved into the American Redstone rocket, used in the early space program.
After the war, rockets were used to study high-altitude conditions, by radio telemetry of temperature and pressure of the atmosphere, detection of cosmic rays, and further research; notably for the Bell X-1 to break the sound barrier. This continued in the US under von Braun and the others, who were destined to become part of the US scientific community.

R-7 8K72 "Vostok" permanently displayed at the Moscow Trade Fair at Ostankino; the rocket is held in place by its railway carrier, which is mounted on four diagonal beams that constitute the display pedestal. Here the railway carrier has tilted the rocket upright as it would do so into its launch pad structure -- which is missing for this display.
Independently, in the Soviet Union's space program research continued under the leadership of the chief designer Sergei Korolev. With the help of German technicians, the V-2 was duplicated and improved as the R-1R-2 and R-5 missiles. German designs were abandoned in the late 1940s, and the foreign workers were sent home. A new series of engines built by Glushko and based on inventions of Aleksei Mihailovich Isaev formed the basis of the first ICBM, the R-7.The R-7 launched the first satellite- Sputnik 1, and later Yuri Gagarin-the first man into space, and the first lunar and planetary probes. This rocket is still in use today. These prestigious events attracted the attention of top politicians, along with additional funds for further research.
One problem that had not been solved was atmospheric reentry. It had been shown that an orbital vehicle easily had enough kinetic energy to vaporize itself, and yet it was known that meteorites can make it down to the ground. The mystery was solved in the US in 1951 when H. Julian Allen and A. J. Eggers, Jr. of the National Advisory Committee for Aeronautics (NACA) made the counterintuitive discovery that a blunt shape (high drag) permitted the most effective heat shield. With this type of shape, around 99% of the energy goes into the air rather than vehicle, and this permitted safe recovery of orbital vehicles.

Prototype of the Mk-2 Reentry Vehicle (RV), based on blunt body theory
The Allen and Eggers discovery, though initially treated as a military secret, was eventually published in 1958. The Blunt Body Theory made possible the heat shield designs that were embodied in the Mercury and all other space capsules and space planes, enabling astronauts to survive the fiery re-entry into Earth's atmosphere.

Cold war

Rockets became extremely important militarily as modern intercontinental ballistic missiles(ICBMs) when it was realized that nuclear weapons carried on a rocket vehicle were essentially impossible for existing defense systems to stop once launched, and ICBM/Launch vehicles such as the R-7, Atlas and Titan became the delivery platform of choice for these weapons.

The Apollo 10 Command Module in orbit around the moon
Fueled partly by the Cold War, the 1960s became the decade of rapid development of rocket technology particularly in the Soviet Union (VostokSoyuzProton) and in the United States (e.g. the X-15 and X-20 Dyna-Soar aircraft). There was also significant research in other countries, such as Britain, Japan, Australia, etc., and a growing use of rockets for Space exploration, with pictures returned from the far side of the Moon and unmanned flights for Mars exploration.
In America the manned programmes, Project MercuryProject Gemini and later the Apollo programme culminated in 1969 with the first manned landing on the moon via the Saturn V, causing the New York Times to retract their earlier editorial implying that spaceflight couldn't work:
Further investigation and experimentation have confirmed the findings of Isaac Newton in the 17th century and it is now definitely established that a rocket can function in a vacuum as well as in an atmosphere. The Times regrets the error.
—New York Times, 17 June 1969 - A Correction
In the 1970s America made further lunar landings, before cancelling the Apollo programme in 1975. The replacement vehicle, the partially reusable 'Space Shuttle' was intended to be cheaper, but this large reduction in costs was largely not achieved. Meanwhile in 1973, the expendable Ariane programme was begun, a launcher that by the year 2000 would capture much of the geosat market.

Current day

Rockets remain a popular military weapon. The use of large battlefield rockets of the V-2 type has given way to guided missiles. However rockets are often used by helicopters and light aircraft for ground attack, being more powerful than machine guns, but without the recoil of a heavy cannon and by the early 1960s air-to-air missiles became favored. Shoulder-launched rocket weapons are widespread in the anti-tank role due to their simplicity, low cost, light weight, accuracy and high level of damage. Current artillery systems such as the MLRS or BM-30 Smerch launch multiple rockets to saturate battlefield targets with munitions.

SpaceShipOne
Economically, rocketry is the enabler of all space technologies particularly satellites, many of which impact people's everyday lives in almost countless ways.
Scientifically, rocketry has opened a window on the universe, allowing the launch of space probes to explore the solar system and space-based telescopes to obtain a clearer view of the rest of the universe.
However, it is probably manned spaceflight that has predominantly caught the imagination of the public. Vehicles such as the Space Shuttle for scientific research, the Soyuz increasingly for orbital tourism and SpaceShipOne for suborbital tourism may show a trend towards greater commercialisation of manned rocketry.

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For details, please visit http://en.wikipedia.org/wiki/Rocket

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