Rocket

C

1

Stability and Control

In order to build safe launch vehicles and accurate missiles, engineers needed to improve rocket stability and control. Robert Goddard used aerodynamic air vanes for his early liquid-fueled rockets. These air vanes helped stabilize and steer rockets by deflecting in desired directions the air through which the rockets moved. Goddard also succeeded with another control—a battery-operated gyroscope within the rocket. The gyroscope was linked to exhaust vanes and straightened the rocket when it began to tilt.

The V-2 rocket used a similar method of control. The exhaust gases passed over a set of four heat-resistant, movable, gyro-controlled graphite exhaust vanes. When the rocket swerved, the vanes were moved to deflect the exhaust, forcing the rocket back to a straight path.

In 1948 the experimental U.S. MX-774 missile pioneered the technique of gimballing, in which the liquid-fueled rocket engine could be tilted for precise steering and stability in its flight. The following year, the Viking sounding rocket started using small maneuvering thrusters around the vehicle.This method was widely adopted and is often used in conjunction with gimballing.

C

2

Rockets for Spaceflight

In the early 1950s, more than 60 captured V-2 rockets were tested at the U.S. Army’s White Sands Proving Grounds in New Mexico. The V-2s gave the Americans valuable experience in handling large rockets, while von Braun’s team helped the Americans develop their own missile program. The first American von Braun rocket was the Redstone, developed in 1951. The engine in the Redstone was a great improvement over that in the V-2. The V-2 had a cumbersome arrangement of 16 cup-shaped injectors, leading some rocket engineers to dub the V-2 “a plumber’s nightmare.” The Redstone used an engine that was originally meant for the Navaho missile and had a flat plate into which the injectors were set.

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The USSR also test-fired captured V-2 rockets and accelerated the Soviet rocket development program. The USSR developed its first intercontinental ballistic missile, the V-2 inspired R-7, around 1954. The world was shocked when, on October 4, 1957, the USSR used a modified version of the R-7 to put Sputnik 1, the world’s first artificial satellite, into orbit around Earth. The United States responded by attempting to launch a satellite with the Vanguard rocket, developed in 1957. The Vanguard fell back to its launch pad and exploded after a few seconds of flight. The United States turned to von Braun’s Redstone, modifying it and renaming it Jupiter-C, to place America’s first satellite, Explorer 1, into orbit on January 31, 1958.

In 1961, after more space “firsts” by the USSR, United States president John F. Kennedy declared a national goal to send a man to the Moon and bring him back safely. Von Braun’s team started work on the huge Saturn V rocket in 1962. On July 20, 1969, Saturn V allowed two Apollo 11 astronauts to land on the Moon. The Saturn V was a magnificent engineering achievement that successfully placed a dozen men on the Moon.

C

3

Missiles of the Cold War

At the same time that the USSR and the United States were racing to build rockets to get them farther into space, the two countries were constantly striving to build bigger ballistic missiles. Ballistic missiles with the power to travel between the two countries are typically three-stage rockets carrying nuclear warheads. Ballistic missiles are designed to destroy targets in enemy countries, but the sheer number and power of the missiles that both countries had in their possession acted as a deterrent to either country ever launching one. The energy put into the ballistic missile programs did benefit the space program, because many rockets designed for missiles were ultimately used as launch vehicles.

The first U.S. intercontinental ballistic missiles (ICBMs), such as the Atlas and the Titan, used liquid propellants. The preparation time, including fueling, of these missiles was long, causing military planners to consider the missiles vulnerable to attack. The next generation Titan II saw improvements in its safe, ordinary temperature, hypergolic (meaning that the oxidizer and fuel ignite on contact) liquid propellant, which cut down the preparation time to a minute. Titan IIs were also kept and launched from underground bombproof structures called silos. Sliding doors in the silo roof opened just prior to launch. The next generation ICBM, the solid-fueled Minuteman, required even less maintenance than its liquid-fueled predecessors, but also launched from silos. During the Cold War, plans were made to carry and launch missiles from specially equipped trains to make detection of the missiles’ location more difficult for the enemy. These schemes were never enacted.

D

Reusable Rockets—The Space Shuttle

Rockets such as the large missiles and launch vehicles in the U.S. Atlas or Titan families, first introduced in the 1950s, were expendable. Each rocket could be used only one time, and each was very expensive. The world’s first reusable rocket engines were those that propel the space shuttle, which was first flown in 1981. The solid rocket boosters that launch the shuttle into orbit can be retrieved and refurbished but are not really reusable. The reusable engines are actually part of the orbiter (the planelike craft often thought of as the shuttle). The space shuttle’s main engine has a built-in electronic controller computer that automatically monitors, regulates, and records all phases of the engine. This computer insures utmost reliability and makes the engine the most sophisticated liquid-fueled rocket engine ever developed. Each of the shuttle’s three engines, clustered at the rear of the orbiter, generates about 1.65 million N (about 375,000 lb) of thrust.

Today, the U.S. space program relies on the fleet of space shuttle orbiters and a number of expendable launch vehicles. Private companies play an increasingly larger role in the design and use of rockets. The European Space Agency (ESA) has developed several launch vehicles, including the advanced Ariane family of rockets. Despite fiscal problems after the breakup of the USSR, Russia still designs and uses rockets, such as the Proton.

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