Helicopter

A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forward, backward, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of VTOL (vertical takeoff and landing) aircraft cannot perform.

The word helicopter is adapted from the French language hélicoptère, coined by Gustave Ponton d'Amécourt in 1861, which originates from the Greek helix (ἕλιξ) "helix, spiral, whirl, convolution" and pteron (πτερόν) "wing". English-language nicknames for helicopter include "chopper", "copter", "helo", "heli", and "whirlybird".

Helicopters were developed and built during the first half-century of flight, with the Focke-Wulf Fw 61 being the first operational helicopter in 1936. Some helicopters reached limited production, but it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production, with 131 aircraft built. Though most earlier designs used more than one main rotor, it is the single main rotor with anti-torque tail rotor configuration that has become the most common helicopter configuration. Tandem rotor helicopters are also in widespread use due to their greater payload capacity. Coaxial helicopters, tiltrotor aircraft, and compound helicopters are all flying today. Quadcopter helicopters pioneered as early as 1907 in France, and other types of multicopter have been developed for specialized applications such as unmanned drones.

For Children (Bartók)

For Children (Hungarian: A Gyermekeknek) is a cycle of short piano pieces composed by Béla Bartók. The collection was originally started in 1908 and completed in 1909, and comprised 85 pieces which were issued in four volumes. Each piece is based on a folk tune, Hungarian in the first two volumes (42 pieces), and Slovakian in the last two (43 pieces). In 1945, Bartók revised the set, removing six pieces which used tunes which had been inaccurately transcribed or found not to be original folk tunes, and substantially changing the harmonisation of a number of others; the cycle, now of 79 pieces, was reissued in two volumes (of 40 and 39 pieces).

The pieces were written as student works, and progress slightly in difficulty through each half of the cycle. However, in modern times, some concert pianists (notably Zoltán Kocsis) have begun including some of them on their recital programs, citing their musical value even apart from their pedagogical origins.

See also

Mikrokosmos