Bell XS-1
The Bell X-1 is a groundbreaking rocket-powered aircraft developed in collaboration between the US military and Bell Aircraft during the mid-1940s. It is celebrated as the first crewed aircraft to surpass the sound barrier, achieving this milestone on October 14, 1947, piloted by Charles "Chuck" Yeager. The design of the X-1 was inspired by the aerodynamics of a bullet, allowing it to stabilize at supersonic speeds, which can exceed 750 miles per hour. Yeager's historic flight, during which he surpassed Mach 1, was notable for the sonic boom it produced, a phenomenon likened to an explosion by onlookers.
The X-1 program marked the beginning of the US X-plane series and served as a precursor to significant advancements in military and civilian aviation. Following its successful flights, the Bell X-1 gained fame, becoming part of American cultural history and contributing to the Space Race's context during the Cold War. The aircraft remains a prominent exhibit at the National Air and Space Museum, where it has been restored to its original paint scheme, showcasing its legacy in aviation history. The achievements associated with the Bell X-1 continue to be recognized as pivotal in the evolution of aeronautics and space exploration.
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Bell XS-1
The Bell X-1 is a rocket-powered plane designed to break the sound barrier. It was the first of a series of experimental aircraft developed by the US military known as X-planes. The US government worked with Bell Aircraft to develop and build the plane in the mid-1940s in the final years of World War II (1939–1945). In October 1947, the Bell X-1 achieved its primary ambition, becoming the first crewed aircraft to travel faster than the speed of sound. The information did not become public until the following June, as the military sought to keep news of the flight secret. The Bell X-1 represents one of the early technological achievements to emerge from the Cold War (1947–-1991), during which the United States and the Soviet Union used scientific accomplishment as a marker of ideological superiority. With the two global superpowers setting their sights on the stars, the inaugural flight of the Bell X-1 signaled a monumental step toward the lofty goals of crewed spaceflight and exploration.
Background
Physicists, engineers, and natural philosophers have long sought to better understand how speed travels. English scientist Isaac Newton (1643–1727) introduced an early formula for determining the speed of sound in the late seventeenth century. The speed of sound refers to how fast sound can travel through an environment, such as underwater or through a piece of wood. Sound accelerates as temperatures warm, making the speed of sound decrease as one moves higher in Earth’s atmosphere, where temperatures become colder. The sound barrier at sea level assumes a temperature of 59°F (15°C). An aircraft approaches the speed of sound faster as it travels above the planet. The Bell X-1 was designed to pass the speed of sound in dry conditions at about 32°F (0°C). This speed is approximately 750 miles per hour (1200 kilometers per hour), but the speed of sound according to surrounding conditions may be referred to as Mach 1. Aircraft that travel less than Mach 1 are subsonic because the speed is less (sub) than sound (sonic), while aircraft capable of speeds faster than Mach 1 are supersonic.
The sound barrier refers to the intense resistance an object encounters as it approaches the speed of sound. It is sometimes referred to as the sonic barrier, and travel faster than the speed of sound can be referred to as supersonic flight. When an object breaks the sound barrier, the resulting sound is called a sonic boom. This sound occurred when the Bell X-1 surpassed the speed of sound. Another common example of a sonic boom can be heard in the crack of a whip. Representatives from Bell Aircraft, including the company’s founder Larry Bell, worked with members of the US military and the National Advisory Committee for Aeronautics (NACA) for several years on developing an aircraft to break the sound barrier before arriving at the Bell X-1.
The Bell X-1 served as the first model in the US X-plane program and also the designation of XS-1, with “X” standing for “experimental” and “S” standing for “supersonic.” Testing had proven a fifty-caliber bullet stable when traveling beyond the speed of sound after being fired from a gun. Developers used the bullet as a model when designing the body of the plane. Building began in 1945, and several glide-tests were performed in 1946. These tests involved dropping the plane and assessing how it handled without its engines turned on. In September 1946, scientists began conducting tests using the plane’s rocket engines.
Overview
During the testing stages of the Bell X-1, the military assumed control over the project. The passage of the National Security Act of 1947 established the US Air Force as a separate military branch, having previously been a part of the Army. After more than a year of testing with other pilots at relatively slow speeds, the military selected Charles “Chuck” Yeager to pilot the plane in the final tests to break the sound barrier. Yeager named the plane “Glamorous Glennis” after his wife, and the military had it painted orange to make it easier to see in the sky.
After conducting some preliminary tests, Yeager took flight in the X-1 over the Mojave Desert in California on October 14, 1947, and became the first pilot to officially break the sound barrier. During that historic flight, the plane surpassed Mach 1 at a speed of more than 800 miles per hour (1287.5 kilometers per hour) at 43,000 feet (13,106.4 meters) above sea level, maintaining supersonic speed for about twenty seconds. Yeager reported that he did not experience a major shock when breaking the sound barrier. However, spectators on the ground reported that the sonic boom sounded and felt like an explosion.
Though Yeager’s flight was successful and noteworthy, the military sought to keep the achievement secret. They failed in their efforts to contain the information, and reports began to appear in the media over the next several months. Further, the US National Aeronautic Association recognized the achievement in 1947 by bestowing the prestigious Robert J. Collier Trophy upon Yeager and those involved in the plane’s development. With the information widely available, the government made an official announcement in June 1948. The X-1 program continued into 1958.
Yeager and the X-1 gained some celebrity after its historic flight. Many Americans continue to regard Yeager as a hero in the twenty-first century. The final flights of “Glamorous Glennis” in 1950 provided footage of the plane to make its Hollywood debut in the 1957 film Jet Pilot, in which Yeager also appeared as a stunt pilot. The filmmakers had repainted the plane. In 1950, the plane entered the collection of the National Air Museum (later renamed the National Air and Space Museum) at the Smithsonian Institution in Washington, DC. For the first several years, the Bell X-1 retained the paint job it received during the film. However, the museum restored the original paint job, including the name “Glamorous Glennis” along the nose, in 1976.
Historians identify Yeager’s flight as an important precursor to the Space Race (1955–1975), an era of the Cold War in which the United States and Soviet Union pursued space exploration to establish geopolitical advantage and foster national pride. The Soviet Union achieved supersonic flight in 1953 and accomplished several early achievements in space travel. In 1958, NACA, the federal agency behind the development of the X-1, joined other federal agencies in forming the National Aeronautics and Space Administration (NASA).
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