An interesting video of US Military conducting refueling operations of their Bell Boeing V-22 Osprey aircraft. The Bell Boeing V-22 Osprey is an American multi-mission, military, tiltrotor aircraft with both a vertical takeoff and landing (VTOL), and short takeoff and landing (STOL) capability. It is designed to combine the functionality of a conventional helicopter with the long-range, high-speed cruise performance of a turboprop aircraft. The V-22 originated from the United States Department of Defense Joint-service Vertical take-off/landing Experimental (JVX) aircraft program started in 1981. The team of Bell Helicopter and Boeing Helicopters was awarded a development contract in 1983 for the tiltrotor aircraft. The Bell Boeing team jointly produce the aircraft.[4] The V-22 first flew in 1989, and began flight testing and design alterations; the complexity and difficulties of being the first tiltrotor intended for military service in the world led to many years of development. The United States Marine Corps began crew training for the Osprey in 2000, and fielded it in 2007; it supplemented and then replaced their Boeing Vertol CH-46 Sea Knights. The Osprey's other operator, the U.S. Air Force, fielded their version of the tiltrotor in 2009. Since entering service with the U.S. Marine Corps and Air Force, the Osprey has been deployed in both combat and rescue operations over Iraq, Afghanistan, Sudan and Libya. Role V/STOL transport National origin United States Manufacturer Bell Helicopter Boeing Rotorcraft Systems First flight 19 March 1989 Introduction 13 June 2007[1] Status In service Primary users United States Marine Corps United States Air Force Produced 1988–present Number built 200+ as of 2014[2] Program cost US$35.6 billion after planned procurement of 408 aircraft[3] Unit cost MV-22: US$69.3 million (flyaway cost for FY2012)[3] Developed from Bell XV-15 Design Overview The Osprey is the world's first production tiltrotor aircraft, with one three-bladed proprotor, turboprop engine, and transmission nacelle mounted on each wingtip. It is classified as a powered lift aircraft by the Federal Aviation Administration.[84] For takeoff and landing, it typically operates as a helicopter with the nacelles vertical and rotors horizontal. Once airborne, the nacelles rotate forward 90° in as little as 12 seconds for horizontal flight, converting the V-22 to a more fuel-efficient, higher speed turboprop aircraft. STOL rolling-takeoff and landing capability is achieved by having the nacelles tilted forward up to 45°.[85][86] Other orientations are possible, such as the "80 Jump" takeoff which uses nacelles at 80° to quickly achieve high altitude and speed.[87] Composite materials make up 43% of the airframe, and the proprotor blades also use composites.[85] For storage, the V-22's rotors fold in 90 seconds and its wing rotates to align, front-to-back, with the fuselage.[88] Due to the requirement for folding rotors, their 38-foot diameter is 5 feet less than optimal for vertical takeoff, resulting in high disk loading.[87] Most missions use fixed wing flight 75% or more of the time, reducing wear and tear and operational costs. This fixed wing flight is higher than typical helicopter missions allowing longer range line-of-sight communications for improved command and control.[25] Heat from the V-22's engines can potentially damage the flight decks of ships. Naval Air Systems Command devised a temporary fix of portable heat shields placed under the engines, and determined that a long-term solution would require redesigning decks with heat resistant coating, passive thermal barriers, and ship structure changes. Similar changes are required for F-35B operations.[89] In 2009, DARPA requested solutions for installing robust flight deck cooling.[90] Propulsion The V-22's two Rolls-Royce AE 1107C engines are connected by drive shafts to a common central gearbox so that one engine can power both proprotors if an engine failure occurs.[66] However, if a proprotor gearbox fails that proprotor cannot be feathered, and both engines must be stopped before an emergency landing.[65] The aircraft's autorotation characteristics are poor partly because the rotors have low inertia.[65] The V-22 has a maximum rotor downwash speed above 80 knots, more than the 64 knots lower limit of a hurricane.[91][92] The rotorwash usually prevents usage of the starboard door in hover, instead the rear ramp is used for rappelling and hoisting.[65][93] Boeing has stated the V-22 design loses 10 percent of its vertical lift over a tiltwing design when operating in helicopter mode because of airflow resistance due to the wings, but that the tiltrotor design has better short takeoff and landing performance.[94] In September 2013, Rolls-Royce announced it had increased the AE-1107C engine's power by 17 percent via the adoption of a new Block 3 turbine, an increase in fuel valve flow capacity, and accompanying software updates.

• published: 18 Dec 2014
• views: 68634