Sikorsky R-4
The Sikorsky R-4 is a two-seat helicopter designed by Igor Sikorsky with a single, three-bladed main rotor and powered by a radial engine. The R-4 was the world's first large-scale mass-produced helicopter and the first helicopter used by the United States Army Air Forces, the United States Navy, the United States Coast Guard and the United Kingdom's Royal Air Force and Royal Navy. In U. S. Navy and U. S. Coast Guard service, the helicopter was known as the Sikorsky HNS-1. In British service it was known as the Hoverfly; the VS-316 was developed from the famous experimental VS-300 helicopter, invented by Igor Sikorsky and publicly demonstrated in 1940. The VS-316 was designated the XR-4, under the United States Army Air Forces' series for "Rotorcraft"; the XR-4 first flew on 14 January 1942 and was accepted by the Army on 30 May 1942. The XR-4 exceeded all the previous helicopter endurance altitude and airspeed records, set before it; the XR-4 completed a 761 mi cross-country flight from Bridgeport, Connecticut, to Wright Field Ohio set a helicopter peak altitude record of 12,000 ft, while achieving 100 flight hours without a major incident and top airspeed approaching 90 mph The British Admiralty, having learned of the VS-300, made a ship available, Empire Mersey, fitted with an 80 ft × 40 ft landing platform, intended to show the USN their work with ship-borne autogyros.
After her loss in 1942 to a U-boat, she was replaced by SS Daghestan. The first deck-landing trials aboard Daghestan were carried out in 1944; the British received. On 5 January 1943, the United States Army Air Forces ordered 29 prototypes; the first three were used for evaluation testing. The YR-4A benefited from a 180 hp Warner R-550-1 engine, compared to the 165 hp R-500-3 in the prototype, a rotor diameter increased by 1 ft. Evaluation of the YR-4A demonstrated a need for further improvements, including moving the tailwheel further aft on the tailboom, venting the exhaust to the side instead of downward, increasing the fuel capacity by 5 US gal; these and other design changes led to the designation of prototypes as YR-4B, which were used for service testing and flight training. United Aircraft announced on 5 November 1944 that the one hundredth helicopter had been completed, that the production rate had reached five every six days. Following the sinking in January 1944 of USS Turner, a Sikorsky R-4 flew life saving blood plasma for the casualties from New York.
On 22–23 April 1944, U. S. Army Lieutenant Carter Harman of the 1st Air Commando Group conducted the first combat rescue by helicopter using a YR-4B in the China-Burma-India theater. Despite the high altitude and capacity for only a single passenger, Harman rescued a downed liaison aircraft pilot and his three British soldier passengers, two at a time. On 22–23 January 1945, another rescue by the R-4 involved several legs for refueling and navigating through passes between mountains nearly 10,000 feet tall, to reach a weather station located at an elevation of 4,700 feet; the higher-than-normal altitude required a downhill run of 20 ft to get airborne. While the R-4 was being used for rescues in Burma and China, it was being used to ferry parts between floating Aviation Repair Units in the South Pacific. On 23 May 1944, six ships set sail with two R-4s on board each vessel; the ships had been configured as floating repair depots for damaged Army Air Forces aircraft in the South Pacific. When the helicopters were not being used to fly the parts from one location to another, they were enlisted for medical evacuation and other mercy missions.
In Royal Air Force service, the R-4 was called the Hoverfly. The Helicopter Training School, formed January 1945 at RAF Andover, was the first British military unit to be equipped with the helicopter. Many RAF Hoverfly Mark Is were transferred to the Royal Navy for training and one was used in 1945/46 by Fairey Aviation to develop rotor systems for their Gyrodyne helicopter; some R-4s had the tailwheel located at the extreme aft end of the boom near the tail rotor while others had it positioned at the midpoint of the boom. Additionally, some had short "stub" exhaust pipes from the engine while others had a much longer one which extended vertically and aft above the main landing gear struts. XR-4 One prototype Model VS-316A with a crew of two and dual controls, 165 hp R-500-3 engine, became XR-4C YR-4A Version with larger rotor diameter and a 180 hp R-550-1 engine. YR-4B Version with detailed changes. R-4B Production version with 200 hp R-550-3 engine. XR-4C Prototype XR-4 re-engined with 180 hp R-550-1 engine with the larger YR-4A-type rotor.
HNS-1 Three YR-4Bs and 22 R-4Bs transferred to the US Navy. Hoverfly I UK military designation of the R-4 for the Royal Air Royal Navy. Sikorsky S-54 An R-4B modified with an observer's seat aft of the main rotor gearbox for trials. United KingdomFleet Air Arm703 Naval Air Squadron 705 Naval Air Squadron 771 Naval Air Squadron Royal Naval Flying School Royal Air ForceHelicopter Training Flight No. 529 Squadron RAF No. 657 Squadron RAF United StatesUnited States Army Air Forces United States Coast Guard United States Navy United KingdomHoverfly Mk.1, KL110 at the Royal Air Force Museum London. Supplied under lend-lease, it arrived in Britain in February 1945, it flew with the RAF the Royal Navy, until 1951. It was used
AeroVironment RQ-11 Raven
The AeroVironment RQ-11 Raven is a small hand-launched remote-controlled unmanned aerial vehicle developed for the United States military, but now adopted by the military forces of many other countries. The RQ-11 Raven was introduced as the FQM-151 in 1999, but in 2002 developed into its current form, resembling an enlarged FAI class F1C free flight model aircraft in general appearance; the craft is powered by a pusher configuration electric motor. The plane can fly up to 6.2 miles at altitudes of appx 500 feet above ground level, over 15,000 feet above mean sea level, at flying speeds of 28–60 mph. The U. S. Army deploys the Raven at company-level; the Raven RQ-11B UAS is manufactured by AeroVironment. It was the winner of the US Army's SUAV program in 2005, went into Full-Rate Production in 2006. Shortly afterwards, it was adopted by the US Marines, the US Air Force for their ongoing FPASS Program, it has been adopted by the military forces of many other countries. More than 19,000 Raven airframes have been delivered to customers worldwide to date.
A new Digital Data Link-enabled version of Raven now in production for US Forces and allies has improved endurance, among many other improvements. The Raven can be either remotely controlled from the ground station or fly autonomous missions using GPS waypoint navigation; the UA can be ordered to return to its launch point by pressing a single command button. Standard mission payloads include an infrared night vision camera; the RQ-11B Raven UA weighs about 1.9 kg, has a flight endurance of 60–90 minutes and an effective operational radius of 10 km. The RQ-11B Raven UA is launched by hand, thrown into the air like a free flight model airplane; the Raven lands itself by auto-piloting to a pre-defined landing point and performing a 45° slope controlled "Autoland" descent. The UAS can provide day or night aerial intelligence, target acquisition, reconnaissance. In mid-2015, the U. S. Marine Corps tested Harris Corporation's Small Secure Data Link, a radio device that fits onto a Raven's nose to provide beyond line-of-sight communications for Marines down to squad level.
Acting as communications nodes for ground forces has become an important function for UASs, but has been restricted to larger platforms like the RQ-4 Global Hawk or RQ-21 Blackjack. Being certified for'Secret' classification and at just 25 cubic inches and weighing 18 oz, the Harris SSDL allows the small Raven UAS to extend communications for troops in the field. In August 2015, selected units began receiving upgrades to their Raven sensors; the Raven Gimbal is a rotating camera with a 360-degree gimbal, which replaces the fixed camera that required maneuvering the entire aircraft to look. The new camera can be switched between day and night settings without landing and swapping sensors. In August 2017 Belgium bought 32 Raven-drones, Luxembourg: 16. RQ-11A Raven A RQ-11B Raven B RQ-11B eight channel RQ-11B DDL Solar Raven – In November 2012, the Air Force Research Laboratory integrated 20 cm2 flexible solar panels into the Raven platform's wing sections using a clear, protective plastic film and an adhesive to augment the existing battery power system, increasing endurance by 60%.
Future improvements include reducing their weight. Integration work is being conducted on the AeroVironment Wasp and the RQ-20 Puma; the Raven is used by the United States Army, Air Force, Marine Corps, Special Operations Command. Additionally, foreign customers include Australia, Italy, Denmark and Czech Republic; as of early 2012, over 19,000 airframes have been shipped, making it the most adopted UAV system in the world today. The British forces in Iraq used Raven equipment; the Royal Danish Army acquired 12 Raven systems in September 2007. A 2010 documentary film, shows Danish forces deploying a Raven in operations around FOB Armadillo in the Helmand province of Afghanistan; the drone makes an appearance being used by the SEAL operators in the 2012 film Act of Valor. The Netherlands MoD has acquired 72 operational RQ-11B systems with a total value of $23.74 million for use within Army reconnaissance units, its Marine Corps and its Special Forces. At the turn of the year 2009 to 2010 the systems were deployed above the village Veen, as part of the Intensification of Civil-Military Cooperation.
In 2012 and 2013 the Raven was loaned by the Defense department to the police department of Almere to combat burglary. In April 2011, the U. S. announced. In June 2011, the U. S. announced $145.4 million in proposed aid for anti-terror efforts in north and east Africa, including four Raven systems to be used by forces from Uganda and Burundi as part of the ongoing African Union peacekeeping mission in Somalia. The US has announced its intent to supply an unspecified number of Ravens to the Ukrainian armed forces. Ukrainian operators criticized the Raven's analog control system that made them vulnerable to jamming and hacking by sophisticated Russian-backed separatists. Iran has claimed it has captured two RQ-11, one "in Shahrivar 1390 and the other one in Aban", it indicated that "much of the data of these drones has been dec
Stinson L-5 Sentinel
The Stinson L-5 Sentinel was a World War II era liaison aircraft used by all branches of the U. S. military and by the British Royal Air Force. It was produced by the Stinson Aircraft Company. Along with the Stinson L-1 Vigilant, the L-5 was the only other American liaison aircraft of World War II, purpose-built for military use and had no civilian counterpart. All other military liaison airplanes adopted during World War II were modified "off-the-shelf" civilian models; the origins of the L-5, affectionately known as the "Flying Jeep", can be traced to the prewar civilian Stinson HW-75. The 75 horsepower civilian high-wing design was built by the Stinson Aircraft Company at Wayne and first flew in 1939; the HW-75 featured two seats up front side-by-side, a third "jumpseat" in the rear on which a small passenger could sit sideways. The design was easy to fly. Shortly after the introduction of the HW-75, Stinson became a subsidiary of the Vultee Aircraft Corporation. Under Vultee management, the HW-75 was equipped with an 80-horsepower four-cylinder engine for the 1940 model year and the HW-75 became known as the Model 105 "Voyager", touting its 105 mph cruise speed.
Fitted with a four-cylinder 90 hp Franklin engine for the 1941 model year, the type became known as the Model 10A. In the postwar era, the fuselage of the Model 10A was enlarged to accommodate four seats, the four-cylinder powerplant was replaced with a Franklin 150 hp six-cylinder engine; this conversion became the Stinson Model 108 Voyager and the only civilian aircraft commercially produced by Stinson after WWII. Six examples of the Model 105 Voyager were equipped with 80 horsepower Continental O-170 engines and provided to the military for testing under the experimental designation YO-54. Evaluated by the Air Corps in 1940 for potential use as a low-cost short-range observation aircraft, it failed to meet performance requirements; the Voyager was completely re-engineered by Stinson into a much stronger and more powerful tandem-seat airplane that met rigorous Army engineering handbook standards for the design of military aircraft. The prototype, designated as the Model V-76 by Vultee / Stinson was accepted by the military after accelerated service trials and entered into service in December 1942 as the Army O-62.
The L-5 carried a pilot and observer in a tandem-seating configuration, preferred by the military for observation work. In March 1943, with the creation of the liaison category of light observation aircraft the designation for Stinson's new purpose-built military design was changed to the L-5; the primary purpose as a liaison aircraft was courier and communication work, artillery spotting and casualty evacuation. The fuselage of models was redesigned so the aircraft could be used as an air ambulance, or for cargo work. With a wider and deeper rear fuselage section and a large rear door that folded downward, a litter patient or 250 pounds of cargo could be loaded aboard; the L-5 series was manufactured between December 1942 and September 1945, during which time 3,590 of the unarmed two-seaters were built for the United States armed forces, making it the second most used light observation aircraft of the war behind the Piper L-4 Cub. The fuselage was constructed using chrome-moly steel tubing covered with doped cotton fabric and the wings and empennage were constructed of spruce and mahogany plywood box spars and plywood ribs and skins covered with fabric.
The use of aluminum, in critically short supply and more urgently needed for other aircraft, was limited to the engine cowling, tail cone, framework for the ailerons and elevator and the landing gear fairings. The L-5 was powered by a six-cylinder 190 horsepower Lycoming O-435 engine. Capable of operating from short unimproved airstrips, the L-5 "Sentinel" delivered personnel, critical intelligence and needed supplies to the front line troops. On return flights, wounded soldiers were evacuated to rear area field hospitals for medical treatment, boosting the morale of combat troops fighting in remote areas. L-5s were used for aerial photography, controlling vehicle convoys, para-dropping food, medical supplies and ammunition, laying communication wire, distributing propaganda leaflets, spraying pesticide, transporting prisoners, directing fighter-bombers to ground targets; the L-5 was popular with Generals and other high-ranking officers for fast, efficient short-range transportation. During the Battle of Okinawa, L-5s operated from an LST using the Brodie landing system which allowed a light aircraft to take off and land without a flat surface by snagging a wire hung between two booms.
One of the L-5s that used the Brodie system off Okinawa is now on display in the Boeing Aviation Hangar facility of the Smithsonian's NASM's Udvar-Hazy Center annex at Dulles Airport just west of Washington, DC. The USAAF, US Marines, US Navy used this aircraft in the European and Far East theaters during World War II, in Korea during the Korean War; the Navy and Marine version of the L-5 through L-5E were designated OY-1, all these aircraft has 12-volt electrical systems. The 24-volt L-5G became the OY-2. Neither the L-5G nor OY-2 saw combat during World War II because production did not begin until July, 1945, just weeks before the war ended, but they were used extensively during the Korean War; the British Royal Air Force procured 40 L-5s and 60 L-5Bs, designated them Sentinel Is and Sentinel II's respectively. These aircraft were used in the India-Burma theater of operations. After World War II, the L-5 was used by the Civil Air Patrol for search and rescue work. M
Vietnam War
The Vietnam War known as the Second Indochina War, in Vietnam as the Resistance War Against America or the American War, was an undeclared war in Vietnam and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. It was the second of the Indochina Wars and was fought between North Vietnam and South Vietnam. North Vietnam was supported by the Soviet Union and other communist allies; the war is considered a Cold War-era proxy war from some US perspectives. It lasted some 19 years with direct U. S. involvement ending in 1973 following the Paris Peace Accords, included the Laotian Civil War and the Cambodian Civil War, resulting in all three countries becoming communist states in 1975. American military advisors began arriving in what was French Indochina in 1950 to support the French in the First Indochina War against the communist-led Viet Minh. Most of the funding for the French war effort was provided by the U. S. After the French quit Indochina in 1954, the US assumed financial and military responsibility for the South Vietnamese state.
The Việt Cộng known as Front national de libération du Sud-Viêt Nam or NLF, a South Vietnamese communist common front aided by the North, initiated a guerrilla war against the South Vietnamese government in 1959. U. S. involvement escalated in 1960, continued in 1961 under President John F. Kennedy, with troop levels surging under the MAAG program from just under a thousand in 1959 to 16,000 in 1963. By 1964, there were 23,000 U. S. troops in Vietnam, but this escalated further following the 1964 Gulf of Tonkin incident, in which a U. S. destroyer was alleged to have clashed with North Vietnamese fast attack craft. In response, the Gulf of Tonkin Resolution gave President Lyndon B. Johnson broad authorization to increase U. S. military presence, deploying ground combat units for the first time and increasing troop levels to 184,000. Past this point, the People's Army of Vietnam known as the North Vietnamese Army engaged in more conventional warfare with US and South Vietnamese forces; every year onward there was significant build-up of US forces despite little progress, with Robert McNamara, one of the principal architects of the war, beginning to express doubts of victory by the end of 1966.
U. S. and South Vietnamese forces relied on air superiority and overwhelming firepower to conduct search and destroy operations, involving ground forces and airstrikes. The U. S. conducted a large-scale strategic bombing campaign against North Vietnam. The Tet Offensive of 1968, proved to be the turning point of the war; the Tet Offensive showed that the end of US involvement was not in sight, increasing domestic skepticism of the war. The unconventional and conventional capabilities of the Army of the Republic of Vietnam increased following a period of neglect and became modeled on heavy firepower-focused doctrines like US forces. Operations crossed international borders. S. forces. Gradual withdrawal of U. S. ground forces began as part of "Vietnamization", which aimed to end American involvement in the war while transferring the task of fighting the communists to the South Vietnamese themselves and began the task of modernizing their armed forces. Direct U. S. military involvement ended on 15 August 1973 as a result of the Case–Church Amendment passed by the U.
S. Congress; the capture of Saigon by the NVA in April 1975 marked the end of the war, North and South Vietnam were reunified the following year. The war exacted a huge human cost in terms of fatalities. Estimates of the number of Vietnamese soldiers and civilians killed vary from 966,000 to 3.8 million. Some 275,000–310,000 Cambodians, 20,000–62,000 Laotians, 58,220 U. S. service members died in the conflict, a further 1,626 remain missing in action. The Sino-Soviet split re-emerged following the lull during the Vietnam War and confllict between North Vietnam and its Cambodian allies in the Royal Government of the National Union of Kampuchea, the newly-formed Democratic Kampuchea begun immediately in a series of border raids by the Khmer Rouge and erupted into the Cambodian–Vietnamese War, with Chinese forces directly intervening in the Sino-Vietnamese War; the end of the war and resumption of the Third Indochina War would precipitate the Vietnamese boat people and the bigger Indochina refugee crisis, which saw an estimated 250,000 people perish at sea.
Within the US the war gave rise to what was referred to as Vietnam Syndrome, a public aversion to American overseas military involvements, which together with Watergate contributed to the crisis of confidence that affected America throughout the 1970s. Various names have been applied to the conflict. Vietnam War is the most used name in English, it has been called the Second Indochina War and the Vietnam Conflict. As there have been several conflicts in Indochina, this particular conflict is known by the names of its primary protagonists to distinguish it from others. In Vietnamese, the war is known as Kháng chiến chống Mỹ, but less formally as'Cuộc chiến tranh Mỹ', it is called Chiến tranh Việt Nam. The primary military organizations involved in the war were as follows: One side consisted of th
Helicopter
A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, to fly forward and laterally; these attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft and many forms of VTOL aircraft cannot perform. The English word helicopter is adapted from the French word hélicoptère, coined by Gustave Ponton d'Amécourt in 1861, which originates from the Greek helix "helix, whirl, convolution" and pteron "wing". English language nicknames for helicopter include "chopper", "copter", "helo", "heli", "whirlybird". Helicopters were developed and built during the first half-century of flight, with the Focke-Wulf Fw 61 being the first operational helicopter in 1936; some helicopters reached limited production, but it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production, with 131 aircraft built. Though most earlier designs used more than one main rotor, it is the single main rotor with anti-torque tail rotor configuration that has become the most common helicopter configuration.
Tandem rotor helicopters are in widespread use due to their greater payload capacity. Coaxial helicopters, tiltrotor aircraft, compound helicopters are all flying today. Quadcopter helicopters pioneered as early as 1907 in France, other types of multicopter have been developed for specialized applications such as unmanned drones; the earliest references for vertical flight came from China. Since around 400 BC, Chinese children have played with bamboo flying toys; this bamboo-copter is spun by rolling a stick attached to a rotor. The spinning creates lift, the toy flies when released; the 4th-century AD Daoist book Baopuzi by Ge Hong describes some of the ideas inherent to rotary wing aircraft. Designs similar to the Chinese helicopter toy appeared in some Renaissance paintings and other works. In the 18th and early 19th centuries Western scientists developed flying machines based on the Chinese toy, it was not until the early 1480s, when Italian polymath Leonardo da Vinci created a design for a machine that could be described as an "aerial screw", that any recorded advancement was made towards vertical flight.
His notes suggested that he built small flying models, but there were no indications for any provision to stop the rotor from making the craft rotate. As scientific knowledge increased and became more accepted, people continued to pursue the idea of vertical flight. In July 1754, Russian Mikhail Lomonosov had developed a small coaxial modeled after the Chinese top but powered by a wound-up spring device and demonstrated it to the Russian Academy of Sciences, it was powered by a spring, was suggested as a method to lift meteorological instruments. In 1783, Christian de Launoy, his mechanic, used a coaxial version of the Chinese top in a model consisting of contrarotating turkey flight feathers as rotor blades, in 1784, demonstrated it to the French Academy of Sciences. Sir George Cayley, influenced by a childhood fascination with the Chinese flying top, developed a model of feathers, similar to that of Launoy and Bienvenu, but powered by rubber bands. By the end of the century, he had progressed to using sheets of tin for rotor blades and springs for power.
His writings on his experiments and models would become influential on future aviation pioneers. Alphonse Pénaud would develop coaxial rotor model helicopter toys in 1870 powered by rubber bands. One of these toys, given as a gift by their father, would inspire the Wright brothers to pursue the dream of flight. In 1861, the word "helicopter" was coined by Gustave de Ponton d'Amécourt, a French inventor who demonstrated a small steam-powered model. While celebrated as an innovative use of a new metal, the model never lifted off the ground. D'Amecourt's linguistic contribution would survive to describe the vertical flight he had envisioned. Steam power was popular with other inventors as well. In 1878 the Italian Enrico Forlanini's unmanned vehicle powered by a steam engine, rose to a height of 12 meters, where it hovered for some 20 seconds after a vertical take-off. Emmanuel Dieuaide's steam-powered design featured counter-rotating rotors powered through a hose from a boiler on the ground. In 1887 Parisian inventor, Gustave built and flew a tethered electric model helicopter.
In July 1901, the maiden flight of Hermann Ganswindt's helicopter took place in Berlin-Schöneberg. A movie covering the event was taken by Max Skladanowsky. In 1885, Thomas Edison was given US$1,000 by James Gordon Bennett, Jr. to conduct experiments towards developing flight. Edison built a helicopter and used the paper for a stock ticker to create guncotton, with which he attempted to power an internal combustion engine; the helicopter was damaged by explosions and one of his workers was badly burned. Edison reported that it would take a motor with a ratio of three to four pounds per horsepower produced to be successful, based on his experiments. Ján Bahýľ, a Slovak inventor, adapted the internal combustion engine to power his helicopter model that reached a height of 0.5 meters in 1901. On 5 May 1905, his helicopter flew for over 1,500 meters. In 1908, Edison patented his own design for a helicopter powered by a gasoline engine with box kites attached to a mast by cables for a rotor, but it never flew.
In 1906, two French brothers and Louis Breguet, began experimenting with airfoils for helicopters. In
Myanmar
Myanmar the Republic of the Union of Myanmar and known as Burma, is a country in Southeast Asia. Myanmar is bordered by India and Bangladesh to its west and Laos to its east and China to its north and northeast. To its south, about one third of Myanmar's total perimeter of 5,876 km forms an uninterrupted coastline of 1,930 km along the Bay of Bengal and the Andaman Sea; the country's 2014 census counted the population to be 51 million people. As of 2017, the population is about 54 million. Myanmar is 676,578 square kilometres in size, its capital city is Naypyidaw, its largest city and former capital is Yangon. Myanmar has been a member of the Association of Southeast Asian Nations since 1997. Early civilisations in Myanmar included the Tibeto-Burman-speaking Pyu city-states in Upper Burma and the Mon kingdoms in Lower Burma. In the 9th century, the Bamar people entered the upper Irrawaddy valley and, following the establishment of the Pagan Kingdom in the 1050s, the Burmese language and Theravada Buddhism became dominant in the country.
The Pagan Kingdom fell. In the 16th century, reunified by the Taungoo dynasty, the country was for a brief period the largest empire in the history of Mainland Southeast Asia; the early 19th century Konbaung dynasty ruled over an area that included modern Myanmar and controlled Manipur and Assam as well. The British took over the administration of Myanmar after three Anglo-Burmese Wars in the 19th century and the country became a British colony. Myanmar was granted independence as a democratic nation. Following a coup d'état in 1962, it became a military dictatorship under the Burma Socialist Programme Party. For most of its independent years, the country has been engrossed in rampant ethnic strife and its myriad ethnic groups have been involved in one of the world's longest-running ongoing civil wars. During this time, the United Nations and several other organisations have reported consistent and systematic human rights violations in the country. In 2011, the military junta was dissolved following a 2010 general election, a nominally civilian government was installed.
This, along with the release of Aung San Suu Kyi and political prisoners, has improved the country's human rights record and foreign relations, has led to the easing of trade and other economic sanctions. There is, continuing criticism of the government's treatment of ethnic minorities, its response to the ethnic insurgency, religious clashes. In the landmark 2015 election, Aung San Suu Kyi's party won a majority in both houses. However, the Burmese military remains a powerful force in politics. Myanmar is a country rich in jade and gems, natural gas and other mineral resources. In 2013, its GDP stood at its GDP at US$221.5 billion. The income gap in Myanmar is among the widest in the world, as a large proportion of the economy is controlled by supporters of the former military government; as of 2016, Myanmar ranks 145 out of 188 countries in human development, according to the Human Development Index. Both the names Myanmar and Burma derive from the earlier Burmese Mranma, an ethnonym for the majority Bamar ethnic group, of uncertain etymology.
The terms are popularly thought to derive from "Brahma Desha" after Brahma. In 1989, the military government changed the English translations of many names dating back to Burma's colonial period or earlier, including that of the country itself: "Burma" became "Myanmar"; the renaming remains a contested issue. Many political and ethnic opposition groups and countries continue to use "Burma" because they do not recognise the legitimacy of the ruling military government or its authority to rename the country. In April 2016, soon after taking office, Aung San Suu Kyi clarified that foreigners are free to use either name, "because there is nothing in the constitution of our country that says that you must use any term in particular"; the country's official full name is the "Republic of the Union of Myanmar". Countries that do not recognise that name use the long form "Union of Burma" instead. In English, the country is popularly known as either "Burma" or "Myanmar". Both these names are derived from the name of the majority Burmese Bamar ethnic group.
Myanmar is considered to be the literary form of the name of the group, while Burma is derived from "Bamar", the colloquial form of the group's name. Depending on the register used, the pronunciation would be Myamah; the name Burma has been in use in English since the 18th century. Burma continues to be used in English by the governments of countries such as the United Kingdom. Official United States policy retains Burma as the country's name, although the State Department's website lists the country as "Burma" and Barack Obama has referred to the country by both names; the government of Canada has in the past used Burma, such as in its 2007 legislation imposing sanctions, but as of the mid-2010s uses Myanmar. The Czech Republic uses Myanmar, although its Ministry of Foreign Affairs mentions both Myanmar and Burma on its website; the United Nations uses Myanmar, as do the Association of Southeast Asian Nations, Russia, China, Bangladesh, Norway and Switzerland. Most English-speaking international news media refer to the country by the name Myanmar, including the BBC, CNN, Al Jazeera and the Australian Broadcasting Corporation /Ra
Sikorsky UH-60 Black Hawk
The Sikorsky UH-60 Black Hawk is a four-bladed, twin-engine, medium-lift utility helicopter manufactured by Sikorsky Aircraft. Sikorsky submitted the S-70 design for the United States Army's Utility Tactical Transport Aircraft System competition in 1972; the Army designated the prototype as the YUH-60A and selected the Black Hawk as the winner of the program in 1976, after a fly-off competition with the Boeing Vertol YUH-61. Named after the Native American war leader Black Hawk, the UH-60A entered service with the U. S. Army in 1979, to replace the Bell UH-1 Iroquois as the Army's tactical transport helicopter; this was followed by the fielding of electronic warfare and special operations variants of the Black Hawk. Improved UH-60L and UH-60M utility variants have been developed. Modified versions have been developed for the U. S. Navy, Air Force, Coast Guard. In addition to U. S. Army use, the UH-60 family has been exported to several nations. Black Hawks have served in combat during conflicts in Grenada, Iraq, the Balkans and other areas in the Middle East.
In the late 1960s, the United States Army began forming requirements for a helicopter to replace the UH-1 Iroquois, designated the program as the Utility Tactical Transport Aircraft System. The Army initiated the development of a new, common turbine engine for its helicopters that would become the General Electric T700. Based on experience in Vietnam, the Army required significant performance and reliability improvements from both UTTAS and the new powerplant; the Army released its UTTAS request for proposals in January 1972. The RFP included air transport requirements. Transport within the C-130 limited length; the UTTAS requirements for improved reliability and lower life-cycle costs resulted in features such as dual-engines with improved hot and high altitude performance, a modular design. Four prototypes were constructed, with the first YUH-60A flying on 17 October 1974. Prior to delivery of the prototypes to the US Army, a preliminary evaluation was conducted in November 1975 to ensure the aircraft could be operated safely during all testing.
Three of the prototypes were delivered to the Army in March 1976, for evaluation against the rival Boeing-Vertol design, the YUH-61A, one was kept by Sikorsky for internal research. The Army selected the UH-60 for production in December 1976. Deliveries of the UH-60A to the Army began in October 1978 and the helicopter entered service in June 1979. After entering service, the helicopter was modified for new missions and roles, including mine laying and medical evacuation. An EH-60 variant was developed to conduct electronic warfare and special operations aviation developed the MH-60 variant to support its missions. Due to weight increases from the addition of mission equipment and other changes, the Army ordered the improved UH-60L in 1987; the new model incorporated all of the modifications made to the UH-60A fleet as standard design features. The UH-60L featured more power and lifting capability with upgraded T700-GE-701C engines and an improved gearbox, both from the SH-60B Seahawk, its external lift capacity increased by 1,000 lb up to 9,000 lb.
The UH-60L incorporated the SH-60B's automatic flight control system for better flight control with the more powerful engines. Production of the L-model began in 1989. Development of the next improved variant, the UH-60M, was approved in 2001, to extend the service life of the UH-60 design into the 2020s; the UH-60M incorporates upgraded T700-GE-701D engines, improved rotor blades, state of the art electronic instrumentation, flight controls and aircraft navigation control. After the U. S. DoD approved low-rate initial production of the new variant, manufacturing began in 2006, with the first of 22 new UH-60Ms delivered in July 2006. After an initial operational evaluation, the Army approved full-rate production and a five-year contract for 1,227 helicopters in December 2007. By March 2009, 100 UH-60M helicopters had been delivered to the Army. In November 2014, US military ordered 102 aircraft of various H-60 types, worth $1.3 billion. Following an operation in May 2011, it emerged that the 160th SOAR used a secret version of the UH-60 modified with low-observable technology which enabled it to evade Pakistani radar.
Analysis of the tail section, the only remaining part of the aircraft which crashed during the operation, revealed extra blades on the tail rotor and other noise reduction measures, making the craft much quieter than conventional UH-60s. The aircraft appeared to include features like special high-tech materials, harsh angles, flat surfaces found only in stealth jets. Low observable versions of the Black Hawk have been studied as far back as the mid-1970s. In September 2012, Sikorsky was awarded a Combat Tempered Platform Demonstration contract to further improve the Black Hawk's durability and survivability; the company is to develop new technologies such as a zero-vibration system, adaptive flight control laws, advanced fire management, a more durable main rotor, full-spectrum crashworthiness, damage tolerant airframe. Improvements to the Black Hawk are to continue until the Future Vertical Lift program is ready to replace it. In December 2014, the 101st Airborne Division began testing new resupply equipment called t