The Same, But Different

Autogiros are similar to helicopters, but operate on different principles. These machines have unpowered blades above the fuselage that rely on airflow to rotate them and provide lift. A conventional propeller, however, drives the aircraft forward. Autogiros have several advantages, including a relatively short takeoff and a near vertical descent. Juan de la Cierva of Spain perfected the autogiro in the early 1920s.

Helicopters made autogiros obsolete in the 1940s and '50s, but today, autogiros -- or gyroplanes, as they're often called -- are making a comeback. Companies like Carter Aviation Technologies in Texas and AutoGyro in Germany are producing modern versions of the autogiro for personal and commercial use.

Helicopter History: Along Came Igor

It was Igor Sikorsky, a Russian-born aeronautical engineer, who developed the first machine with all of the qualities we associate with modern helicopters. Interestingly, Sikorsky's early helicopters -- circa 1910 -- were failures, and he abandoned his efforts so he could focus on fixed-wing airplanes.

After emigrating to the United States and starting Sikorsky Aviation Corporation in Bridgeport, Conn., he once again turned his attention to vertical flight. In 1931, Sikorsky submitted a patent for a modern-looking helicopter design featuring a single main rotor and tail rotor. Eight years later, the first incarnation of this design -- the VS-300 -- lifted Sikorsky into the air. The VS-300 featured a 75-horsepower Lycoming engine connected to a main rotor with three blades and a two-bladed tail rotor. It also provided mechanisms to control the machine's flight. Two inputs, known as the collective and cyclic-pitch sticks, enabled a pilot to change the orientation of the blades to produce lift and enable lateral movement.

This was the first practical helicopter, but it still needed some refinement so it didn't ride like a bucking bronco. Sikorsky continued to make improvements, and on May 6, 1941, the VS-300 broke the world helicopter endurance record by staying aloft for 1 hour, 32 minutes and 26.1 seconds. Other engineers and innovations quickly followed. Notable among the early helicopter pioneers were Arthur Young, Frank Piasecki and Stanley Hiller. Young, backed by Bell Aircraft Corp., developed the Bell 30 helicopter and then the Bell 47, the first commercially certified helicopter. Piasecki designed the single-seater PV2 in 1943, but became better known for large cargo helicopters powered by two main rotors. And Hiller produced several helicopter models including the UH-12, which saw action in Korea and Vietnam.

Up next, we'll look at the basic parts of a modern helicopter to understand what makes these strange machines fly.