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MD Helicopters MD 500
The MD Helicopters MD 500 series is an American family of light utility civilian and military helicopters. The MD 500 was developed from the Hughes 500, a civilian version of the US Army's OH-6A Cayuse/Loach. The series currently includes the MD 500E, MD 520N, and MD 530F. The MD 500 was initially produced by Hughes Helicopters as the ''Hughes 500''. Since being introduced in 1967, numerous models have been produced, often featuring a more powerful engine or a five-bladed main rotor in place of the original four-blade counterpart. The MD 500 has been commonly used for utility work, particularly the ''MD 530F''; it has also proven to be popular with law enforcement agencies. Production of the type was continued into the twenty-first century by Hughes' successor companies, McDonnell Douglas Helicopter Systems, and subsequently MD Helicopters. While the MD 500 series has been largely operated by civil customers, it has occasionally seen military use, even to the extent of perfor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
WikiProject Aircraft
A WikiProject, or Wikiproject, is an affinity group for contributors with shared goals within the Wikimedia movement. WikiProjects are prevalent within the largest wiki, Wikipedia, and exist to varying degrees within Wikimedia project, sibling projects such as Wiktionary, Wikiquote, Wikidata, and Wikisource. They also exist in different languages, and translation of articles is a form of their collaboration. During the COVID-19 pandemic, CBS News noted the role of Wikipedia's WikiProject Medicine in maintaining the accuracy of articles related to the disease. Another WikiProject that has drawn attention is WikiProject Women Scientists, which was profiled by ''Smithsonian Magazine, Smithsonian'' for its efforts to improve coverage of women scientists which the profile noted had "helped increase the number of female scientists on Wikipedia from around 1,600 to over 5,000". On Wikipedia Some Wikipedia WikiProjects are substantial enough to engage in cooperative activities with outsi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Light Observation Helicopter
The Light Observation Helicopter (LOH) program was a United States Army program to evaluate, develop and field a light scout helicopter to replace the Army's aging Bell OH-13 Sioux. It gained impetus with the advent of the Vietnam War, and was aided by advances in helicopter technology, specifically the development of the turboshaft engine. History In July 1953, the Office of Lieutenant General (United States), Lieutenant General John E. Dahlquist, Chief, Army Field Forces (AFF), forwarded desirable military characteristics for a two-place reconnaissance helicopter to Army Headquarters. Nearly a year later, in May 1954, Dahlquist's office once again emphasized the need for replacement aircraft and recommended procurement of troop test quantities of the YH-32 Hornet, YH-32. Preliminary evaluation of the YH-32 design revealed that the aircraft was unsuitable for the mission, and the tests were canceled.Weinert 1991, p. 205. In 1955, the Army Field Forces were transformed into t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Torque
In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. When being referred to as moment of force, it is commonly denoted by . Just as a linear force is a push or a pull applied to a body, a torque can be thought of as a twist applied to an object with respect to a chosen point; for example, driving a screw uses torque to force it into an object, which is applied by the screwdriver rotating around its axis to the drives on the head. Historical terminology The term ''torque'' (from Latin , 'to twist') is said to have been suggested by James Thomson and appeared in print in April, 1884. Usage is attested the same year by Silvanus P. Thompson in the first edition of ''Dynamo-Electric Machinery''. Thompson describes his usage of the term as follows: Today, torque is referred to using d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coandă Effect
The Coandă effect ( or ) is the tendency of a jet (fluid), fluid jet to stay attached to a surface of any form. ''Merriam-Webster'' describes it as "the tendency of a jet of fluid emerging from an orifice to follow an adjacent flat or curved surface and to entrain fluid from the surroundings so that a region of lower pressure develops." It is named after Romanian inventor Henri Coandă, who was the first to recognize the practical application of the phenomenon in aircraft design around 1910. It was first documented explicitly in two patents issued in 1936. Discovery An early description of this phenomenon was provided by Thomas Young (scientist), Thomas Young in a lecture given to The Royal Society in 1800: More than a hundred years later, Henri Coandă identified an application of the effect during experiments with his Coandă-1910 aircraft, which mounted an unusual engine he designed. The motor-driven turbine pushed hot air rearward, and Coandă noticed that the airflow w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NOTAR
NOTAR ("no tail rotor") is a helicopter system which avoids the use of a tail rotor. It was developed by MD Helicopters, McDonnell Douglas Helicopter Systems (through their acquisition of Hughes Helicopters). The system uses a fan inside the tail boom to build a high volume of low-pressure air, which exits through two slots and creates a boundary layer flow of air along the tailboom utilizing the Coandă effect. The boundary layer changes the direction of airflow around the tailboom, creating thrust opposite the motion imparted to the fuselage by the torque effect of the main rotor. Directional yaw control is gained through a vented, rotating drum at the end of the tailboom, called the direct jet thruster. Advocates of NOTAR assert that the system offers quieter and safer operation than a traditional tail rotor. Development The use of directed air to provide anti-torque control had been tested as early as 1945 in the British Cierva W.9. During 1957, a Spanish prototype designed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Md500n
The MD5 message-digest algorithm is a widely used hash function producing a 128-bit hash value. MD5 was designed by Ronald Rivest in 1991 to replace an earlier hash function MD4, and was specified in 1992 as RFC 1321. MD5 can be used as a checksum to verify data integrity against unintentional corruption. Historically it was widely used as a cryptographic hash function; however it has been found to suffer from extensive vulnerabilities. It remains suitable for other non-cryptographic purposes, for example for determining the partition for a particular key in a partitioned database, and may be preferred due to lower computational requirements than more recent Secure Hash Algorithms. History and cryptanalysis MD5 is one in a series of message digest algorithms designed by Professor Ronald Rivest of MIT (Rivest, 1992). When analytic work indicated that MD5's predecessor MD4 was likely to be insecure, Rivest designed MD5 in 1991 as a secure replacement. ( Hans Dobbertin did indee ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MD 500 Defender
The McDonnell Douglas Helicopter Systems MD 500 Defender is a light multi-role military helicopter based on the MD Helicopters MD 500, MD 500 light utility helicopter and Hughes OH-6 Cayuse, OH-6 Cayuse Light Observation Helicopter. Design and development The original OH-6 Cayuse helicopter proved its worth during the Vietnam War in the light helicopter role. The designers at Hughes Helicopters, Hughes realized there was a market for a light multi-mission helicopter with an improved equipment fit than the OH-6 and Model 500M. The resulting design was the ''Model 500MD Defender'' which first flew in 1976. It was tailored for specific roles including unarmed observation and an armed scout helicopter equipped with BGM-71 TOW, TOW anti-tank missiles. An Anti-submarine warfare, anti-submarine version was developed with a search radar, magnetic anomaly detector and the capability to carry lightweight aerial torpedoes. The helicopter was popular with customers like Kenya Air Force, Ken ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boeing
The Boeing Company, or simply Boeing (), is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, and missiles worldwide. The company also provides leasing and product support services. Boeing is among the largest global aerospace manufacturers; it is the fourth-largest defense contractor in the world based on 2022 revenue and is the largest exporter in the United States by dollar value. Boeing was founded by William E. Boeing in Seattle, Washington, on July 15, 1916. The present corporation is the result of the merger of Boeing with McDonnell Douglas on August 1, 1997. As of 2023, the Boeing Company's corporate headquarters is located in the Crystal City neighborhood of Arlington County, Virginia. The company is organized into three primary divisions: Boeing Commercial Airplanes (BCA), Boeing Defense, Space & Security (BDS), and Boeing Global Services (BGS). In 2021, Boeing recorded $62.3billion in sales. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
McDonnell Douglas
McDonnell Douglas Corporation was a major American Aerospace manufacturer, aerospace manufacturing corporation and defense contractor, formed by the merger of McDonnell Aircraft and the Douglas Aircraft Company in 1967. Between then and its own merger with Boeing in 1997, it produced well-known commercial and military aircraft, such as the McDonnell Douglas DC-10, DC-10 and the McDonnell Douglas MD-80, MD-80 airliners, the McDonnell Douglas F-15 Eagle, F-15 Eagle air superiority fighter, and the McDonnell Douglas F/A-18 Hornet, F/A-18 Hornet multirole combat aircraft, multirole fighter. The corporation's headquarters were at St. Louis Lambert International Airport, near St. Louis, Missouri. History Background The company was formed from the firms of James Smith McDonnell and Donald Wills Douglas, Sr., Donald Wills Douglas in 1967. Both men were of Scottish ancestry, were graduates of the Massachusetts Institute of Technology, and had worked for the aircraft manufacturer Glenn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hot And High
In aviation, hot and high is a condition of low air density due to high ambient temperature and high airport elevation. Air density decreases with increasing temperature and altitude. The lower air density reduces the power output from an aircraft's engine and also requires a higher true airspeed before the aircraft can become airborne. Aviators gauge air density by calculating the density altitude. An airport may be especially hot ''or'' high, without the other condition being present. Temperature and pressure altitude can change from one hour to the next. The fact that temperature generally decreases as altitude increases mitigates the "hot and high" effect to a small extent. Negative effects of reduced engine power due to hot and high conditions * Airplanes require a longer takeoff run, potentially exceeding the amount of available runway. * Reduced take-off power hampers an aircraft's ability to climb. In some cases, an aircraft may be unable to climb rapidly enough to cl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bell 206
The Bell 206 is a family of two-bladed, single- and twin-engined helicopters, manufactured by Bell Helicopter at its Mirabel, Quebec, plant. Originally developed as the Bell YOH-4 for the United States Army's Light Observation Helicopter program, it was not selected by the Army. Bell redesigned the airframe and successfully marketed the aircraft commercially as the five-place Bell 206A JetRanger. The new design was eventually selected by the Army as the OH-58 Kiowa. Bell also developed a seven-place LongRanger, which was later offered with a twin-engined option as the TwinRanger, while Tridair Helicopters offers a similar conversion of the LongRanger called the Gemini ST. The ICAO-assigned model designation "B06" is used on flight plans for the JetRanger and LongRanger, and the designation "B06T" is used for the twin-engined TwinRangers. Development Origins and JetRanger On October 14, 1960, the United States Navy solicited responses from 25 aircraft manufacturers to a req ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maiden Flight
The maiden flight, also known as first flight, of an aircraft is the first occasion on which it leaves the ground under its own power. The same term is also used for the first launch of rockets. In the early days of aviation it could be dangerous, because the exact handling characteristics of the aircraft were generally unknown. The maiden flight of a new type is almost invariably flown by a highly experienced test pilot. Maiden flights are usually accompanied by a chase plane, to verify items like altitude, airspeed, and general airworthiness. A maiden flight is only one stage in the development of an aircraft type. Unless the type is a pure research aircraft (such as the X-15), the aircraft must be tested extensively to ensure that it delivers the desired performance with an acceptable margin of safety. In the case of civilian aircraft, a new type must be certified by a governing agency (such as the Federal Aviation Administration in the United States) before it can enter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
