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Dutch Roll
Dutch roll is an aircraft motion consisting of an out-of- phase combination of "tail-wagging" (yaw) and rocking from side to side (roll). This yaw-roll coupling is one of the basic flight dynamic modes (others include phugoid, short period, and spiral divergence). This mode resembles the motion of a skier who is simultaneously yawing and rolling from side to side. This motion is normally well damped in most light aircraft, though some aircraft with well-damped Dutch roll modes can experience a degradation in damping as airspeed decreases and altitude increases. Dutch roll stability can be artificially increased by the installation of a yaw damper. Wings placed well above the center of gravity, swept wings, and dihedral wings tend to increase the roll restoring force, and therefore increase the Dutch roll tendencies; this is why high-winged aircraft often are slightly anhedral, and transport-category swept-wing aircraft are equipped with yaw dampers. A similar phenomenon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slip (aerodynamic)
A slip is an aerodynamic state where an aircraft is moving ''somewhat'' sideways as well as forward relative to the oncoming airflow or relative wind. In other words, for a conventional aircraft, the nose will be pointing in the opposite direction to the bank of the wing(s). The aircraft is not in coordinated flight and therefore is flying inefficiently. Background Flying in a slip is aerodynamically inefficient, since the lift-to-drag ratio is reduced. More drag is at play consuming energy but not producing lift. Inexperienced or inattentive pilots will often enter slips unintentionally during turns by failing to coordinate the aircraft with the rudder. Airplanes can readily enter into a slip climbing out from take-off on a windy day. If left unchecked, climb performance will suffer. This is especially dangerous if there are nearby obstructions under the climb path and the aircraft is underpowered or heavily loaded. A slip can also be a ''piloting maneuver'' where the pilot d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Academy Of Sciences
The National Academy of Sciences (NAS) is a United States nonprofit, NGO, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the National Academy of Medicine (NAM). As a national academy, new members of the organization are elected annually by current members, based on their distinguished and continuing achievements in original research. Election to the National Academy is one of the highest honors in the scientific field in the United States. Member of the National Academy of Sciences, Members of the National Academy of Sciences serve ''pro bono'' as "advisers to the nation" on science, engineering, and medicine. The group holds a congressional charter under Title 36 of the United States Code. Congress legislated and President Abraham Lincoln signed an Act of Congress (1863) establishing the National Academy of Sciences as an independent, trusted nongovernmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proceedings Of The National Academy Of Sciences Of The United States Of America
''Proceedings of the National Academy of Sciences of the United States of America'' (often abbreviated ''PNAS'' or ''PNAS USA'') is a peer-reviewed multidisciplinary scientific journal. It is the official journal of the National Academy of Sciences, published since 1915, and publishes original research, scientific reviews, commentaries, and letters. According to ''Journal Citation Reports'', the journal has a 2022 impact factor of 9.4. ''PNAS'' is the second most cited scientific journal, with more than 1.9 million cumulative citations from 2008 to 2018. In the past, ''PNAS'' has been described variously as "prestigious", "sedate", "renowned" and "high impact". ''PNAS'' is a delayed open-access journal, with an embargo period of six months that can be bypassed for an author fee ( hybrid open access). Since September 2017, open access articles are published under a Creative Commons license. Since January 2019, ''PNAS'' has been online-only, although print issues are available ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jerome C
Jerome (; ; ; – 30 September 420), also known as Jerome of Stridon, was an early Christian priest, confessor, theologian, translator, and historian; he is commonly known as Saint Jerome. He is best known for his translation of the Bible into Latin (the translation that became known as the Vulgate) and his commentaries on the whole Bible. Jerome attempted to create a translation of the Old Testament based on a Hebrew version, rather than the Septuagint, as prior Latin Bible translations had done. His list of writings is extensive. In addition to his biblical works, he wrote polemical and historical essays, always from a theologian's perspective. Jerome was known for his teachings on Christian moral life, especially those in cosmopolitan centers such as Rome. He often focused on women's lives and identified how a woman devoted to Jesus should live her life. This focus stemmed from his close patron relationships with several prominent female ascetics who were members of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Skating
Ice skating is the Human-powered transport, self-propulsion and gliding of a person across an ice surface, using metal-bladed ice skates. People skate for various reasons, including recreation (fun), exercise, competitive sports, and commuting. Ice skating may be performed on naturally frozen bodies of water, such as ponds, lakes, canals, and rivers, and on human-made ice surfaces both indoors and outdoors. Natural ice surfaces used by skaters can accommodate a variety of winter sports which generally require an enclosed area, but are also used by skaters who need Ice rink#Tracks and trails, ice tracks and trails for Tour skating, distance skating and speed skating. Man-made ice surfaces include ice rinks, ice hockey rinks, bandy fields, ice tracks required for the sport of ice cross downhill, and arenas. Various formal sports involving ice skating have emerged since the 19th century. Ice hockey, bandy, rinkball, and ringette are team sports played with, respectively, a flat sl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adverse Yaw
Adverse yaw is the natural and undesirable tendency for an aircraft to yaw in the opposite direction of a roll. It is caused by the difference in lift and drag of each wing. The effect can be greatly minimized with ailerons deliberately designed to create drag when deflected upward and/or mechanisms which automatically apply some amount of coordinated rudder. As the major causes of adverse yaw vary with lift, any fixed-ratio mechanism will fail to fully solve the problem across all flight conditions and thus any manually operated aircraft will require some amount of rudder input from the pilot in order to maintain coordinated flight. History Adverse yaw was first experienced by the Wright brothers when they were unable to perform controlled turns in their 1901 glider which had no vertical control surface. Orville Wright later described the glider's lack of directional control. Causes Adverse yaw is a secondary effect of the inclination of the lift vectors on the wing due to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aircraft Pilot
An aircraft pilot or aviator is a person who controls the flight of an aircraft by operating its directional flight controls. Some other aircrew members, such as navigators or flight engineers, are also considered aviators because they are involved in operating the aircraft's navigation and engine systems. Other aircrew members, such as drone operators, flight attendants, mechanics and ground crew, are not classified as aviators. In recognition of the pilots' qualifications and responsibilities, most militaries and many airlines worldwide award aviator badges to their pilots. Definition The first recorded use of the term ''aviator'' (''aviateur'' in French) was in 1887, as a variation of ''aviation'', from the Latin ''avis'' (meaning ''bird''), coined in 1863 by in ''Aviation Ou Navigation Aérienne'' ("Aviation or Air Navigation"). The term ''aviatrix'' (''aviatrice'' in French), now archaic, was formerly used for a female pilot. The term ''aviator'' (''aviateur'' i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerobatic Maneuver
Aerobatic maneuvers are flight paths putting aircraft in unusual attitudes, in air shows, dogfights or competition aerobatics. Aerobatics can be performed by a single aircraft or in Formation flying, formation with several others. Nearly all aircraft are capable of performing aerobatics maneuvers of some kind, although it may not be legal or safe to do so in certain aircraft. Aerobatics consist of five basic maneuvers: * Lines (both horizontal and vertical), * loops, * rolls, * spins, and * hammerheads. Most aerobatic figures are composites of these basic maneuvers with rolls superimposed. A loop is when the pilot pulls the plane up into the vertical, continues around until they are heading back in the same direction, like making a 360 degree turn, except it is in the vertical plane instead of the horizontal. The pilot will be inverted (upside down) at the top of the loop. A loop can also be performed by rolling inverted and making the same maneuver but diving towards the gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tex Johnston
Alvin Melvin "Tex" Johnston (August 18, 1914 – October 29, 1998) was an American test pilot for Bell Aircraft and the Boeing Company. Early life Johnston was born August 18, 1914, in Admire, Kansas, to farmers Alva and Ella Johnston. He had his first airplane ride in 1925, at 11 years old, when a barnstormer landed near his family farm. At the age of 15, Johnston used his newspaper route money to purchase a wrecked Cessna glider. After repairing the glider, Johnston's father would pull it behind their car and Johnston would release the tow cable and glide to a landing in a nearby field. After graduating from Emporia High School in 1932, Johnston enrolled in the airplane mechanic program at the Spartan School of Aeronautics in Tulsa, Oklahoma. Once Johnston became an apprentice mechanic, he was able to offset his flight training costs by working on the school's aircraft. After graduating from Spartan, Johnston joined Inman's Flying Circus, working as both a pilot and mec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Airliner
An airliner is a type of airplane for transporting passengers and air cargo. Such aircraft are most often operated by airlines. The modern and most common variant of the airliner is a long, tube shaped, and jet powered aircraft. The largest of them are wide-body jets which are also called twin-aisle because they generally have two separate aisles running from the front to the back of the passenger cabin. These are usually used for long-haul flights between airline hubs and major cities. A smaller, more common class of airliners is the narrow-body or single-aisle. These are generally used for short to medium-distance flights with fewer passengers than their wide-body counterparts. Regional airliners typically seat fewer than 100 passengers and may be powered by turbofans or turboprops. These airliners are the non- mainline counterparts to the larger aircraft operated by the major carriers, legacy carriers, and flag carriers, and are used to feed traffic into the large a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light-sport Aircraft
A light-sport aircraft (LSA), or light sport aircraft, is a category of small, lightweight aircraft that are simple to fly. LSAs tend to be heavier and more sophisticated than ultralight (aka "microlight") aircraft, but LSA restrictions on weight and performance separates the category from established general aviation, GA aircraft. There is no standard worldwide description of an LSA. LSAs in different countries The Civil aviation authority, civil aviation authorities in different countries have their own particular specifications and regulations which define the LSA category. For example, in Australia the Civil Aviation Safety Authority defines a light-sport aircraft as a heavier-than-air or lighter-than-air craft, other than a helicopter, with a maximum gross takeoff weight of not more than for lighter-than-air craft; for heavier-than-air craft not intended for operation on water; or for aircraft intended for operation on water. It must have a maximum stall (flight), stall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
