Helicopters

Aircraft that use rotating blades to achieve lift and are characterized by vertical flight and the ability to hover, or remain stationary in the air. The first rudimentary helicopters saw action during World War II, but helicopter development accelerated greatly during the following decades. Today, helicopters are a critical component of U.S. military force and are used in a variety of roles, including ground attack, troop transport, and supply.

Early Evolution

The first recorded examples of vertical flying machines are Chinese tops dating from the 400s BCE. They consisted of feathers mounted on the end of a stick, which, when twirled rapidly between the hands and released, took flight. The Italian Renaissance artist and inventor Leonardo da Vinci designed an “aerial screw” in 1483 that anticipated some of the principles of helicopter flight. However, he never built his machine.

For years, the main impediment to creating a workable helicopter was the lack of an engine powerful enough to lift an aircraft but light enough not to weigh the craft down. In the early 1900s, designers from many different countries attempted to build machines capable of vertical flight. Quite a few of these actually made short hops, but none was able to sustain flight for more than a minute or two. Russian designer Igor Sikorsky, considered the father of the modern helicopter, built several unsuccessful prototypes during this time. He stated that he had to await “better engines, lighter materials, and experienced mechanics.”

In the 1920s and 1930s, Spaniard Juan de la Cierva designed the first working predecessor to the helicopter, a device called the autogyro. The early models were essentially airplanes with a rotating blade attached to enable near-vertical flight. Later models were closer in design and performance to a modern helicopter, but they still lacked the ability to hover.

The First Modern Helicopters

Work on the autogyro led to the development of more sophisticated vertical-flight aircraft during the mid-to late 1930s. In 1935, the French aviation pioneers Louis Breuget and Rene Dorand built a large craft that broke records for distance (44 km, or about 25 miles) and sustained flight (62 minutes) by a vertical lift machine. German aircraft designers also created workable helicopter models at this time, but both the French and German design programs were interrupted by the start of World War II.

Sikorsky, who had emigrated to the United States before the war, received a patent for a machine of his own in 1935, known to workers at his Connecticut factory as “Igor's Nightmare” because of its complexity. Despite the doubts of many of his own people, by 1941 Sikorsky had perfected a craft designated the R-4, which became the first helicopter to go into mass production. Two years later, Sikorsky introduced the improved R-5, several hundred of which saw service in World War II.

Evolving Technology

Helicopter technology and the use of helicopters by the military accelerated substantially after World War II. During the Korean War (1950–53), UN and U.S. forces used helicopters for reconnaissance, for evacuation of wounded soldiers from combat areas, and for small deliveries of supplies or troops. The mid-1950s saw the development of helicopters that were capable of carrying larger numbers of troops and supplies. The Sikorsky Company led the way in developing craft such as the Sky Crane, which was capable of lifting several tons of equipment, including vehicles such as trucks and artillery pieces.

...