The Eurocopter X3 (X-Cubed) is an experimental high-speed compound helicopter under development by Eurocopter. On June, 20th 2013 a Bloomberg L.P. special video report stated that the X3 is the World's Fastest Helicopter by reaching a top speed of 472 km/h on several test flights.[1] The X3 demonstrator is based on a Eurocopter EC155 helicopter with the addition of short span wings each fitted with a tractor propeller. The tractor propellers are gear driven from the two main turboshaft engines which also drive the five-bladed main rotor. The helicopter is designed to prove the concept of a high-speed helicopter which depends on the slowing down of the rotor speed to avoid drag from the advancing blade tip, and to avoid retreating blade stall by unloading the rotor while a small wing[2] is intended to provide up to 80% lift instead.[3] The X3 first flew on 6 September 2010 from French Délégation Générale de l'Armement facility at Istres-Le Tubé Air Base. On 12 May 2011 the X3 flew at a speed of 430 km/h (267 mph) for several minutes.[4][5] Conventional helicopters use tail rotors to counter the torque effect of the main rotor. The starboard propeller of the X3 has a higher rotational speed than the port to counter the torque effect.[6] Eurocopter intends to demonstrate the X3 in the USA in summer 2012. A product using X3 technology may come in 2020.[7] On May 12, 2011 it demonstrated a speed of 232 knots (267 mph; 430 km/h).[8][9] On June 7, 2013 it demonstrated a speed of 255 knots (293 mph; 472 km/h)[10][11] beating Sikorsky X2's world record, becoming the fastest compound helicopter as of June 2013. General characteristics Crew: 2 Powerplant: 2 × Rolls-Royce Turbomeca RTM322 turboshaft engines, 1,693 kW (2,270 hp) each Propellers: 2-bladed five-bladed tractor propellers gear driven from main engines. Performance Maximum speed: 472 km/h; 293 mph (255 kn) at roughly 10,000 ft (3,048 m)[11] Cruising speed: 407 km/h (253 mph; 220 kn) [8] Service ceiling: 3,810 m (12,500 ft) Rate of climb: 25 m/s (5,000 ft/min) [13][14] Radio-controlled helicopters (also RC helicopters) are model aircraft which are distinct from RC airplanes because of the differences in construction, aerodynamics, and flight training. Several basic designs of RC helicopters exist, of which some (such as those with collective pitch, meaning blades which rotate on their longitudinal axis to vary or reverse lift so the pitch can be altered and can therefore change the angle of attack) are more maneuverable than others. The more maneuverable designs are often harder to fly, but benefit from greater aerobatic capabilities. Flight controls allow pilots to control the collective and throttle (usually linked together), the cyclic controls (pitch and roll), and the tail rotor (yaw). Controlling these in unison enables the helicopter to perform most[citation needed] of the same maneuvres as full-sized helicopters, such as hovering and backwards flight, and many that full-sized helicopters cannot, such as inverted flight (where collective pitch control provides negative blade pitch to hold heli up inverted, and pitch/yaw controls must be reversed by pilot). 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 forwards, backwards, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft would usually not be able to take off or land. The capability to hover efficiently for extended periods of time allows a helicopter to accomplish tasks that fixed-wing aircraft and other forms of vertical takeoff and landing aircraft cannot perform. The word helicopter is adapted from the French language hélicoptère, coined by Gustave de Ponton d'Amecourt in 1861, which originates from the Greek helix/helik- (ἕλιξ) = "twisted, curved"[1] and pteron (πτερόν) = "wing".[2][3][4] English-language nicknames used for helicopters include chopper, helo 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,[5] with 131 aircraft built.[6] 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. Quadrotor helicopters and other types of multicopter have been developed for specialized applications. The earliest references for vertical flight have come from China. Since around 400 BC,[7] Chinese children have played with bamboo flying toys.[8][9][10] The bamboo-copter is spun by rolling a stick attached to a rotor.

• published: 07 Aug 2014
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