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Inherently Unstable
In aviation, an aircraft is said to have relaxed stability if it has low or negative stability. An aircraft with negative stability will have a tendency to change its pitch and bank angles spontaneously. An aircraft with negative stability cannot be trimmed to maintain a certain attitude, and will, when disturbed in pitch or roll, continue to pitch or roll in the direction of the disturbance at an ever-increasing rate. This can be contrasted with the behaviour of an aircraft with positive stability, which can be trimmed to fly at a certain attitude, which it will continue to maintain in the absence of control input, and, if perturbed, will oscillate in simple harmonic motion on a decreasing scale around, and eventually return to, the trimmed attitude. A positively stable aircraft will also resist any bank movement. A Cessna 152 is an example of a stable aircraft. Similarly, an aircraft with neutral stability will not return to its original attitude without control input, but wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aviation
Aviation includes the activities surrounding mechanical flight and the aircraft industry. ''Aircraft'' include fixed-wing and rotary-wing types, morphable wings, wing-less lifting bodies, as well as lighter-than-air aircraft such as hot air balloons and airships. Aviation began in the 18th century with the development of the hot air balloon, an apparatus capable of atmospheric displacement through buoyancy. Clément Ader built the "Ader Éole" in France and made an uncontrolled, powered hop in 1890. This was the first powered aircraft, although it did not achieve controlled flight. Some of the most significant advancements in aviation technology came with the controlled gliding flying of Otto Lilienthal in 1896. A major leap followed with the construction of the '' Wright Flyer'', the first powered airplane by the Wright brothers in the early 1900s. Since that time, aviation has been technologically revolutionized by the introduction of the jet engine which enabl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wright Brothers
The Wright brothers, Orville Wright (August 19, 1871 – January 30, 1948) and Wilbur Wright (April 16, 1867 – May 30, 1912), were American aviation List of aviation pioneers, pioneers generally credited with inventing, building, and flying the world's first successful airplane. They made the first controlled, sustained flight of an engine-powered, Aircraft#Heavier-than-air – aerodynes, heavier-than-air aircraft with the ''Wright Flyer'' on December 17, 1903, four miles (6 km) south of Kitty Hawk, North Carolina, at what is now known as Kill Devil Hills, North Carolina, Kill Devil Hills. In 1904 the Wright brothers developed the ''Wright Flyer II'', which made longer-duration flights including the first circle, followed in 1905 by the first truly practical fixed-wing aircraft, the ''Wright Flyer III''. The brothers' breakthrough invention was their creation of a Flight dynamics (aircraft), three-axis control system, which enabled the pilot to steer the aircraft effec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
McDonnell Douglas MD-11
The McDonnell Douglas MD-11 is an American trijet wide-body aircraft, wide-body airliner manufactured by American manufacturer McDonnell Douglas (MDC) and later by Boeing. Following McDonnell Douglas DC-10, DC-10 development studies, the MD-11 program was launched on December 30, 1986. Assembly of the first prototype began on March 9, 1988. Its maiden flight occurred on January 10, 1990, and it achieved Federal Aviation Administration (FAA) certification on November 8. The first delivery was to Finnair on December 7 and it entered service on December 20, 1990. It retains the basic trijet configuration of the DC-10 with updated GE CF6-80C2 or PW4000 turbofan engines. Its wingspan is slightly larger than the DC-10 and it has Wingtip device, winglets. Its maximum takeoff weight (MTOW) is increased by % to . Its fuselage is stretched by % to to accommodate 298 passengers in three classes over a Range (aeronautics), range of up to . It features a glass cockpit that eliminates the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fly-by-wire
Fly-by-wire (FBW) is a system that replaces the conventional aircraft flight control system#Hydro-mechanical, manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals, and flight control computers determine how to move the actuators at each control surface to provide the ordered response. Implementations either use Aircraft flight control system, mechanical flight control backup systems or else are fully electronic.Fly by Wire Flight Control Systems Sutherland Improved fully fly-by-wire systems interpret the pilot's control inputs as a desired outcome and calculate the control surface positions required to achieve that outcome; this results in various combinations of rudder, Elevator (a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar Cross Section
Radar cross-section (RCS), denoted σ, also called radar signature, is a measure of how detectable an object is by radar. A larger RCS indicates that an object is more easily detected. An object reflects a limited amount of radar energy back to the source. The factors that influence this include: *the material with which the target is made; *the size of the target relative to the wavelength of the illuminating radar signal; *the absolute size of the target; *the incident angle (angle at which the radar beam hits a particular portion of the target, which depends upon the shape of the target and its orientation to the radar source); *the reflected angle (angle at which the reflected beam leaves the part of the target hit; it depends upon incident angle); *the polarization of the radiation transmitted and received with respect to the orientation of the target. While important in detecting targets, strength of emitter and distance are not factors that affect the calculation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-117
The Lockheed F-117 Nighthawk is an officially retired American single-seat, subsonic, Twinjet, twin-engined, stealth aircraft, stealth attack aircraft developed by Lockheed Corporation, Lockheed's secretive Skunk Works division and operated by the United States Air Force (USAF). It was the first operational aircraft to be designed with stealth technology. Work on what would become the F-117 commenced in the 1970s as a means of countering increasingly sophisticated Soviet surface-to-air missiles (SAMs). During 1976, the Defense Advanced Research Projects Agency (DARPA) issued Lockheed a contract to produce the ''Lockheed Have Blue, Have Blue'' technology demonstrator, the test data from which validated the concept. On 1 November 1978, Lockheed decided to proceed with the F-117 development program. Five prototypes were produced; the first of which performed its maiden flight in 1981 at Groom Lake, Nevada. The first production F-117 was delivered in 1982, and its initial operat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lockheed Martin
The Lockheed Martin Corporation is an American Arms industry, defense and aerospace manufacturer with worldwide interests. It was formed by the merger of Lockheed Corporation with Martin Marietta on March 15, 1995. It is headquartered in North Bethesda, Maryland, United States. As of January 2022, Lockheed Martin employs approximately 121,000 employees worldwide, including about 60,000 engineers and scientists. Reports from 2024 estimate that Lockheed Martin Corporation (LMT) holds a market cap of around $139.7 billion. Lockheed Martin is one of the largest companies in the aerospace, military support, security, and technologies industry. It was the world's largest defense contractor by revenue for fiscal year 2014.POC Top 20 Defence Contractors of 2014 . Retrieved: July 2015 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stealth Aircraft
Stealth aircraft are designed to avoid detection using a variety of technologies that reduce reflection/emission of radar, infrared, visible light, radio frequency (RF) spectrum, and audio, collectively known as stealth technology. The F-117 Nighthawk was the first operational aircraft explicitly designed around stealth technology. Other examples of stealth aircraft include the Northrop Grumman B-2 Spirit, B-2 Spirit, the B-21 Raider, the Lockheed Martin F-22 Raptor, F-22 Raptor, the F-35 Lightning II, the Chengdu J-20, and the Sukhoi Su-57. While no aircraft is completely invisible to radar, stealth aircraft make it more difficult for conventional radar to detect or track the aircraft effectively, increasing the odds of an aircraft avoiding detection by enemy radar and/or avoiding being successfully targeted by Semi-active radar guidance, radar guided weapons. Stealth is a combination of passive low observable (LO) features and active emitters such as low-probability-of-interc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Usaf
The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its origins to 1 August 1907, as a part of the United States Army Signal Corps, the USAF was established by transfer of personnel from the Army Air Forces with the enactment of the National Security Act of 1947. It is the second youngest branch of the United States Armed Forces and the fourth in United States order of precedence, order of precedence. The United States Air Force articulates its core missions as air supremacy, intelligence, surveillance, target acquisition, and reconnaissance, global integrated intelligence, surveillance and reconnaissance, airlift, rapid global mobility, Strategic bombing, global strike, and command and control. The United States Department of the Air Force, Department of the Air Force, which serves as the USAF's ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piper PA-25 Pawnee
The PA-25 Pawnee is an agricultural aircraft produced by Piper Aircraft between 1959 and 1981. It remains a widely used aircraft in agricultural spraying and is also used as a tow plane, or tug, for launching Glider aircraft, gliders or for towing banners. In 1988, the design rights and support responsibility were sold to Latino Americana de Aviación of Argentina. Design and development Most agricultural aircraft before 1949 were converted military aircraft and it was in that year that Fred Weick, based at Texas A&M University, designed a dedicated agricultural aircraft: the Texas A&M College Ag-1, AG-1. The AG-1 first flew on 1 December 1950.Peperell/Smith 1987, pp.113-120 During 1953, Fred Weick was approached by Piper to become a consultant on the agricultural version of the Piper PA-18 Super Cub, PA-18, the PA-18A, in particular to design and test a distributor for dust and seeds. A few weeks later, Piper sponsored Texas A&M University to design a dedicated agricultural air ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coordinated Flight
In aviation, coordinated flight of an aircraft is flight without sideslip.Clancy, L.J., ''Aerodynamics'', Section 14.6 When an aircraft is flying with zero sideslip a turn and bank indicator installed on the aircraft's instrument panel usually shows the ball in the center of the spirit level. The occupants perceive no lateral acceleration of the aircraft and their weight to be acting straight downward into their seats. Particular care to maintain coordinated flight is required by the pilot when entering and leaving turns.Transport Canada: ''Flight Training Manual'', 4th edition, page 9. Gage Publishing, 1994. Advantages Coordinated flight is usually preferred over uncoordinated flight for the following reasons: *it is more comfortable for the occupants *it minimises the drag force on the aircraft *it causes fuel to be drawn equally from tanks in both wings *it minimises the risk of entering a spin Instrumentation Airplanes and helicopters are usually equipped with a t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wilbur Wright
The Wright brothers, Orville Wright (August 19, 1871 – January 30, 1948) and Wilbur Wright (April 16, 1867 – May 30, 1912), were American aviation List of aviation pioneers, pioneers generally credited with inventing, building, and flying the world's first successful airplane. They made the first controlled, sustained flight of an engine-powered, Aircraft#Heavier-than-air – aerodynes, heavier-than-air aircraft with the ''Wright Flyer'' on December 17, 1903, four miles (6 km) south of Kitty Hawk, North Carolina, at what is now known as Kill Devil Hills, North Carolina, Kill Devil Hills. In 1904 the Wright brothers developed the ''Wright Flyer II'', which made longer-duration flights including the first circle, followed in 1905 by the first truly practical fixed-wing aircraft, the ''Wright Flyer III''. The brothers' breakthrough invention was their creation of a Flight dynamics (aircraft), three-axis control system, which enabled the pilot to steer the aircraft effec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
