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Pilot-induced Oscillation
Pilot-induced oscillations (PIOs), as defined by MIL-HDBK-1797A, are ''sustained or uncontrollable oscillations resulting from efforts of the pilot to control the aircraft''. They occur when the pilot of an aircraft inadvertently commands an often increasing series of corrections in opposite directions, each an attempt to cover the aircraft's reaction to the previous input with an overcorrection in the opposite direction. An aircraft in such a condition can appear to be "porpoising" switching between upward and downward directions. As such it is a coupling of the frequency of the pilot's inputs and the aircraft's own frequency. During flight test, pilot-induced oscillation is one of the handling qualities factors that is analyzed, with the aircraft being graded by an established scale (chart at right). In order to avoid any assumption that oscillation is necessarily the fault of the pilot, new terms have been suggested to replace ''pilot-induced oscillation''. These include ''airc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stall (flight)
In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases.Crane, Dale: ''Dictionary of Aeronautical Terms, third edition'', p. 486. Aviation Supplies & Academics, 1997. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is typically about 15°, but it may vary significantly depending on the fluid, foil, and Reynolds number. Stalls in fixed-wing flight are often experienced as a sudden reduction in lift as the pilot increases the wing's angle of attack and exceeds its critical angle of attack (which may be due to slowing down below stall speed in level flight). A stall does not mean that the engine(s) have stopped working, or that the aircraft has stopped moving—the effect is the same even in an unpowered glider aircraft. Vectored thrust in aircraft is used to maintain altitude or controlled flight with wings stalled by replacing lost wing lift with engine or propeller t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Owners And Pilots Association
The Aircraft Owners and Pilots Association (AOPA) is a Frederick, Maryland-based American non-profit political organization that advocates for general aviation. AOPA's membership consists mainly of general aviation pilots in the United States. AOPA exists to serve the interests of its members as aircraft owners and pilots and to promote the economy, safety, utility, and popularity of flight in general aviation aircraft. With 384,915 members in 2012, AOPA is the largest aviation association in the world, although it had decreased in membership from 414,224 in 2010, a loss of 7% in two years. AOPA is affiliated with other similar organizations in other countries through membership in the International Council of Aircraft Owner and Pilot Associations (IAOPA). In 2015, AOPA was inducted into the International Air & Space Hall of Fame at the San Diego Air & Space Museum. History The organization started at Wings Field in Blue Bell, Pennsylvania. On 24 April 1932, The Philadelp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phugoid
In aviation, a phugoid or fugoid is an aircraft motion in which the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes "downhill" and "uphill". This is one of the basic flight dynamics modes of an aircraft (others include short period, roll subsidence, dutch roll, and spiral divergence), and is a classic example of a positive feedback system. Detailed description The phugoid has a nearly constant angle of attack but varying pitch, caused by a repeated exchange of airspeed and altitude. It can be excited by an elevator singlet (a short, sharp deflection followed by a return to the centered position) resulting in a pitch increase with no change in trim from the cruise condition. As speed decays, the nose drops below the horizon. Speed increases, and the nose climbs above the horizon. Periods can vary from under 30 seconds for light aircraft to minutes for larger aircraft. Microlight aircraft typically s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thomas A
Thomas may refer to: People * List of people with given name Thomas * Thomas (name) * Thomas (surname) * Saint Thomas (other) * Thomas Aquinas (1225–1274) Italian Dominican friar, philosopher, and Doctor of the Church * Thomas the Apostle * Thomas (bishop of the East Angles) (fl. 640s–650s), medieval Bishop of the East Angles * Thomas (Archdeacon of Barnstaple) (fl. 1203), Archdeacon of Barnstaple * Thomas, Count of Perche (1195–1217), Count of Perche * Thomas (bishop of Finland) (1248), first known Bishop of Finland * Thomas, Earl of Mar (1330–1377), 14th-century Earl, Aberdeen, Scotland Geography Places in the United States * Thomas, Illinois * Thomas, Indiana * Thomas, Oklahoma * Thomas, Oregon * Thomas, South Dakota * Thomas, Virginia * Thomas, Washington * Thomas, West Virginia * Thomas County (other) * Thomas Township (other) Elsewhere * Thomas Glacier (Greenland) Arts, entertainment, and media * ''Thomas'' (Burton novel) 1969 nove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edwards Air Force Base
Edwards Air Force Base (AFB) is a United States Air Force installation in California. Most of the base sits in Kern County, but its eastern end is in San Bernardino County and a southern arm is in Los Angeles County. The hub of the base is Edwards, California. The base was named after World War II USAAF veteran and test pilot Capt. Glen Edwards in 1950; prior to then the facility was named Muroc Air Force Base. It is the home of the Air Force Test Center, Air Force Test Pilot School, and NASA's Armstrong Flight Research Center. It is the Air Force Materiel Command center for conducting and supporting research and development of flight, as well as testing and evaluating aerospace systems from concept to combat. It also hosts many test activities conducted by America's commercial aerospace industry. Notable occurrences at Edwards include Chuck Yeager's flight that broke the sound barrier in the Bell X-1, test flights of the North American X-15, the first landings of the S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
F-22 Raptor
The Lockheed Martin F-22 Raptor is an American single-seat, twin-engine, all-weather stealth tactical fighter aircraft developed for the United States Air Force (USAF). As the result of the USAF's Advanced Tactical Fighter (ATF) program, the aircraft was designed as an air superiority fighter, but also has ground attack, electronic warfare, and signals intelligence capabilities. The prime contractor, Lockheed Martin, built most of the F-22's airframe and weapons systems and conducted final assembly, while Boeing provided the wings, aft fuselage, avionics integration, and training systems. The aircraft first flew in 1997 and was variously designated F-22 and F/A-22 before it formally entered service in December 2005 as the F-22A. Although the USAF had originally planned to buy a total of 750 ATFs, the program was cut to 187 operational aircraft in 2009 due to high costs, a lack of air-to-air missions due to the focus on counterinsurgency operations at the time of production, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accidents And Incidents Involving The JAS 39 Gripen
The JAS 39 Gripen is a fighter aircraft manufactured by the Swedish aerospace company Saab. Eight Gripens were destroyed in crashes, two of them before the delivery to the Swedish Air Force. These aircraft included one prototype, one production aircraft and three in service with the Swedish Air Force. Two Gripens in service with the Hungarian Air Force, and one in service with the Royal Thai Air Force, were also destroyed in crashes. In addition, one aircraft was lost in a ground accident during an engine test, for a total of nine hull losses. Crashes during testing February 1989 On 2 February 1989, the first prototype JAS 39-1 crashed on its sixth flight, when attempting to land in Linköping. The accident was filmed in a now-famous recording by a crew from Sveriges Television's news program ''Aktuellt''.. The pilot, Lars Rådeström, remained in the tumbling aircraft, and escaped with a fractured elbow and some minor injuries. The crash was the result of pilot-induced oscill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
JAS 39 Gripen
The Saab JAS 39 Gripen (; English: ''griffin'') is a light single-engine multirole fighter aircraft manufactured by the Swedish aerospace and defense company Saab AB. The Gripen has a delta wing and canard configuration with relaxed stability design and fly-by-wire flight controls. Later aircraft are fully NATO interoperable. , more than 271 Gripens of all models, A–F, have been built. In 1979, the Swedish government began development studies for "an aircraft for fighter, attack, and reconnaissance" (''ett jakt-, attack- och spaningsflygplan'', hence "JAS") to replace the Saab 35 Draken and 37 Viggen in the Swedish Air Force. A new design from Saab was selected and developed as the JAS 39. The first flight occurred in 1988, with delivery of the first serial production airplane in 1993. It entered service with the Swedish Air Force in 1996. Upgraded variants, featuring more advanced avionics and adaptations for longer mission times, began entering service in 2003. To mark ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fly-by-wire
Fly-by-wire (FBW) is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires, and flight control computers determine how to move the actuators at each control surface to provide the ordered response. It can use mechanical flight control backup systems (like the Boeing 777) or use fully fly-by-wire controls.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, aileron, flaps and engine controls in different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Popular Mechanics
''Popular Mechanics'' (sometimes PM or PopMech) is a magazine of popular science and technology, featuring automotive, home, outdoor, electronics, science, do-it-yourself, and technology topics. Military topics, aviation and transportation of all types, space, tools and gadgets are commonly featured. It was founded in 1902 by Henry Haven Windsor, who was the editor and—as owner of the Popular Mechanics Company—the publisher. For decades, the tagline of the monthly magazine was "Written so you can understand it." In 1958, PM was purchased by the Hearst Corporation, now Hearst Communications. In 2013, the US edition changed from twelve to ten issues per year, and in 2014 the tagline was changed to "How your world works." The magazine added a podcast in recent years, including regular features ''Most Useful Podcast Ever'' and ''How Your World Works''. History ''Popular Mechanics'' was founded in Chicago by Henry Haven Windsor, with the first issue dated January 11, 1902. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Dynamics F-16 Fighting Falcon
The General Dynamics F-16 Fighting Falcon is a single-engine Multirole combat aircraft, multirole fighter aircraft originally developed by General Dynamics for the United States Air Force (USAF). Designed as an air superiority day fighter, it evolved into a successful night fighter, all-weather multirole aircraft. Over 4,600 aircraft have been built since production was approved in 1976. Although no longer being purchased by the U.S. Air Force, improved versions are being built for export customers. In 1993, General Dynamics sold its aircraft manufacturing business to the Lockheed Corporation, which in turn became part of Lockheed Martin after a 1995 merger with Martin Marietta. The Fighting Falcon's key features include a frameless bubble canopy for good visibility, side-stick, side-mounted control stick to ease control while maneuvering, an ejection seat reclined 30 degrees from vertical to reduce the effect of g-forces on the Aircraft pilot, pilot, and the first use of a rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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