The Douglas DC-3 is a fixed-wing propeller-driven airliner that revolutionized air transport in the 1930s and 1940s. Its lasting effect on the airline industry and World War II makes it one of the most significant transport aircraft produced, it has a cruise speed of 207 mph, capacity of 21 to 32 passengers or 6,000 lbs of cargo and a range of 1,500 mi. The DC-3 is a twin-engine metal monoplane with a tailwheel-type landing gear and was developed as a larger, improved 14-bed sleeper version of the Douglas DC-2, it had many exceptional qualities compared to previous aircraft. It had good range and could operate from short runways, it carried passengers in greater comfort. Before the war it pioneered many air travel routes, it made worldwide flights possible. It is considered the first airliner. Civil DC-3 production ended in 1942 at 607 aircraft. Military versions, including the C-47 Skytrain, Russian- and Japanese-built versions, brought total production to over 16,000. Following the war, the airliner market was flooded with surplus C-47s and other ex-military transport aircraft, Douglas' attempts to produce an upgraded DC-3 failed due to cost.
Post-war, the DC-3 was made obsolete on main routes by more advanced types such as the Douglas DC-6 and Lockheed Constellation, but the design proved exceptionally adaptable and useful. Large numbers continue to see service in a wide variety of niche roles well into the 21st century. In 2013 it was estimated that 2,000 DC-3s and military derivatives were still flying, a testament to the durability of the design. "DC" stands for "Douglas Commercial". The DC-3 was the culmination of a development effort that began after an inquiry from Transcontinental and Western Airlines to Donald Douglas. TWA's rival in transcontinental air service, United Airlines, was starting service with the Boeing 247 and Boeing refused to sell any 247s to other airlines until United's order for 60 aircraft had been filled. TWA asked Douglas to build an aircraft that would allow TWA to compete with United. Douglas' design, the 1933 DC-1, was promising, led to the DC-2 in 1934; the DC-2 was a success. The DC-3 resulted from a marathon telephone call from American Airlines CEO C. R. Smith to Donald Douglas, when Smith persuaded a reluctant Douglas to design a sleeper aircraft based on the DC-2 to replace American's Curtiss Condor II biplanes.
Douglas agreed to go ahead with development only after Smith informed him of American's intention to purchase twenty aircraft. The new aircraft was engineered by a team led by chief engineer Arthur E. Raymond over the next two years, the prototype DST first flew on December 17, 1935, its cabin was 92 in wide, a version with 21 seats instead of the 14–16 sleeping berths of the DST was given the designation DC-3. There was no prototype DC-3; the DC-3 and DST popularized air travel in the United States. Eastbound transcontinental flights could cross the U. S. in about 15 hours with three refueling stops. A few years earlier such a trip entailed short hops in slower and shorter-range aircraft during the day, coupled with train travel overnight. A variety of radial engines were available for the DC-3. Early-production civilian aircraft used Wright R-1820 Cyclone 9s, but aircraft used the Pratt & Whitney R-1830 Twin Wasp, which gave better high-altitude and single-engine performance. Five DC-3S Super DC-3s with Pratt & Whitney R-2000 Twin Wasps were built in the late 1940s, three of which entered airline service.
Total production of all variants was 16,079. More than 400 remained in commercial service in 1998. Production was as follows: 607 civil variants of the DC-3. Production of DSTs ended in mid-1941 and civil DC-3 production ended in early 1943, although dozens of DSTs and DC-3s ordered by airlines that were produced between 1941 and 1943 were impressed into the US military while still on the production line. Military versions were produced until the end of the war in 1945. A larger, more powerful Super DC-3 was launched in 1949 to positive reviews; the civilian market, was flooded with second-hand C-47s, many of which were converted to passenger and cargo versions. Only five Super DC-3s were built, three of them were delivered for commercial use; the prototype Super DC-3 served the U. S. Navy with the designation YC-129 alongside 100 R4Ds, upgraded to the Super DC-3 specification. From the early 1950s, some DC-3s were modified to use Rolls-Royce Dart engines, as in the Conroy Turbo Three. Other conversions featured Armstrong Siddeley Pratt & Whitney PT6A turbines.
The Greenwich Aircraft Corp DC-3-TP is a conversion with an extended fuselage and with Pratt & Whitney Canada PT6A-65AR or PT6A-67R engines fitted. The Basler BT-67 is a conversion of the DC-3/C-47. Basler refurbishes C-47s and DC-3s at Oshkosh, fitting them with Pratt & Whitney Ca
Southern Air Inc. a wholly owned subsidiary of Atlas Air Worldwide Holdings, is a global air cargo carrier headquartered in Florence, Kentucky. It is a certified U. S. FAA part 121 cargo carrier and is one of only two U. S.-based cargo airlines operating the 777F. Southern Air is the first company to provide ACMI service for the wide-body Boeing 777F; the airline operates an all-Boeing fleet of aircraft: Boeing 777F, the Boeing 737-400SF. Its wide range of services includes: long-term ACMI, on-demand commercial charters, as well as Department of Defense Civil Reserve Air Fleet. Southern Air’s operations support some of the world’s largest combination carriers as well as government agencies and non-government organizations; the airline was established on March 5, 1999 by James Neff, out of the assets of Southern Air Transport and started operations in November 1999. On September 7, 2007, Oak Hill Capital Partners acquired majority ownership of Southern Air and merged Cargo 360 into the airline. In early 2010, Southern Air took delivery of two Boeing 777 freighters.
At the same time, Southern Air introduced new aircraft livery as well as new corporate branding. In early 2011, Southern Air entered into a multiple year contract with DHL Aviation; the same year Southern Air retired the fleet of Boeing 747-200, 747-300 and 747-400BDSF models. On 28 September 2012, Southern Air filed for Chapter 11 bankruptcy protection and emerged from bankruptcy in early 2013. In 2014, Southern Air took delivery of five 737-400SF passenger-to-cargo converted aircraft. On April 7, 2016, Atlas Air Worldwide Holdings purchased Southern Air for $110 million in an all-cash deal; the transaction included Worldwide Air Logistics Group, Inc. and its two operating subsidiaries, Southern Air, Inc. and Florida West International Airways, Inc. In 2017 Atlas Air Worldwide Holdings shutdown Florida West International Airways and cancelled its operating certificate; as of 2018, Southern Air and the pilots' union have signed an agreement changing the work rules to match those work rules contained in the Atlas Air pilots' contract.
According to its union, Southern Air pilots have operated under one of the worst contracts in the aviation industry and the company has had problems with pilot hiring and retention. This has made it more difficult for Southern to meet growing customer demands. Official website
Myrtle Beach, South Carolina
Myrtle Beach is a coastal city on the East Coast of the United States in Horry County, South Carolina. It is in the center of a large and continuous 60-mile stretch of beach known as "The Grand Strand" in northeastern South Carolina. Ranked as the second fastest-growing metropolitan area in the country, Myrtle Beach is one of the major centers of tourism in South Carolina and the United States because of the city's warm subtropical climate and extensive beaches, attracting an estimated 14 million visitors each year; as of the 2010 census, the population of the city was 27,109, in 2016 the estimated population was 32,240. The Myrtle Beach metropolitan area had an estimated population in 2016 of 449,495. Prior to the arrival of Europeans, the Long Bay area was inhabited by the native Waccamaw tribe; the Waccamaw fished along the shore around Little River. Waties Island, the primary barrier island along Long Bay, has evidence of burial and shell mounds, remains of the visiting Waccamaw; the first European settlers along Long Bay arrived in the late 18th century, attempting to extend the plantation system outward towards the ocean.
Records are sparse from this period, with most of the recorded history pieced together from old land grant documents. These settlers were met with mixed results, producing unremarkable quantities of indigo and tobacco, as the coast's soil was sandy and most of the crop yields were of an inferior quality. Prior to the American Revolution, the area along the future Grand Strand was uninhabited. Several families received land grants along the coast, including the Witherses: John, Richard and Mary; this family received an area around present-day Wither's Swash known as Myrtle Swash or the Eight-Mile Swash. A separate grant was granted to James Minor, including a barrier island named Minor Island, now Waties Island, off the coast near Little River. Mary Withers' gravestone at Prince George Winyah Episcopal Church speaks to the remoteness of the former Strand: "She gave up the pleasures of Society and retired to Long Bay, where she resided a great part of her life devoted to the welfare of her children."As the American colonies gained independence, the area remained unchanged, the coast remained barren.
George Washington scouted out the Southern states during his term, traveling down the King's Highway. He was led across Wither's Swash to Georgetown by Jeremiah Vereen; the Withers family remained one of the few settlers around Myrtle Beach for the next half-century. In 1822, a strong hurricane swept the house of R. F. Withers into the ocean, drowning 18 people inside; the tragedy made. Left unattended, the area began to return to forest; the Burroughs and Collins Company of Conway, predecessor of modern-day Burroughs & Chapin, purchased much of the Withers family's land in 1881, the growing community was called "New Town" around the start of the 20th century. A post office named "Withers" was established to serve the site of the old Swash in 1888. On February 28, 1899, Burroughs and Collins received a charter to build the Conway & Seashore Railroad to transport timber from the coast to inland customers; the railroad began daily service on May 1900, with two wood-burning locomotives. One of the engines was dubbed The Black Maria and came second-hand from a North Carolina logging operation.
After the railroad was finished, employees of the lumber and railroad company would take train flatcars down to the beach area on their free weekends, becoming the first Grand Strand tourists. The railroad terminus was nicknamed contrasting it with the "Old Town", or Conway. Around the start of the 20th century, Franklin Burroughs envisioned turning New Town into a tourist destination rivaling the Florida and northeastern beaches. Burroughs died in 1897, but his sons completed the railroad's expansion to the beach and opened the Seaside Inn in 1901. Around 1900, a contest was held to name the area, Burroughs' wife suggested honoring the locally abundant shrub, the southern wax myrtle; the Withers post office changed its name to "Myrtle Beach" soon afterward. It incorporated as a town in 1938 and as a city in 1957. In 1937, Myrtle Beach Municipal Airport was built, it was converted into a military base. Commercial flights began in 1976 and shared the runway for over 15 years until the air base closed in 1993.
Since the airport has been named Myrtle Beach International Airport. In 2010 plans to build a new terminal were approved. In 1940, Kings Highway was paved, giving Myrtle Beach its first primary highway; the Myrtle Heights-Oak Park Historic District, Myrtle Beach Atlantic Coast Line Railroad Station, Ocean Forest Country Club, Pleasant Inn, Rainbow Court are listed on the National Register of Historic Places. Listed were the Chesterfield Inn and the Myrtle Beach Pavilion, both now demolished; the Gay Dolphin Gift Cove on the Boardwalk was built in 1946, sells seashells and Myrtle Beach souvenirs. It claims to be the "nation's largest gift shop". Myrtle Beach has been separated from the continental United States since 1936 by the Intracoastal Waterway, forcing the city and area in general to develop within a small distance from the coast. In part due to this separation, the area directly northwest of Myrtle Beach, across the waterway, remained rural for a while, whereas its northeastern and southwestern ends were bordered by other developed tourist towns, North Myrtle Beach and Surfside Beach.
Since the inland portion of the Myrtle Beach area has developed dramatically. Myrtle Beach is 67 miles (108 k
Georgia (U.S. state)
Georgia is a state in the Southeastern United States. It began as a British colony in 1733, the last and southernmost of the original Thirteen Colonies to be established. Named after King George II of Great Britain, the Province of Georgia covered the area from South Carolina south to Spanish Florida and west to French Louisiana at the Mississippi River. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788. In 1802–1804, western Georgia was split to the Mississippi Territory, which split to form Alabama with part of former West Florida in 1819. Georgia declared its secession from the Union on January 19, 1861, was one of the original seven Confederate states, it was the last state to be restored to the Union, on July 15, 1870. Georgia is the 8th most populous of the 50 United States. From 2007 to 2008, 14 of Georgia's counties ranked among the nation's 100 fastest-growing, second only to Texas. Georgia is known as the Empire State of the South. Atlanta, the state's capital and most populous city, has been named a global city.
Atlanta's metropolitan area contains about 55% of the population of the entire state. Georgia is bordered to the north by Tennessee and North Carolina, to the northeast by South Carolina, to the southeast by the Atlantic Ocean, to the south by Florida, to the west by Alabama; the state's northernmost part is in the Blue Ridge Mountains, part of the Appalachian Mountains system. The Piedmont extends through the central part of the state from the foothills of the Blue Ridge to the Fall Line, where the rivers cascade down in elevation to the coastal plain of the state's southern part. Georgia's highest point is Brasstown Bald at 4,784 feet above sea level. Of the states east of the Mississippi River, Georgia is the largest in land area. Before settlement by Europeans, Georgia was inhabited by the mound building cultures; the British colony of Georgia was founded by James Oglethorpe on February 12, 1733. The colony was administered by the Trustees for the Establishment of the Colony of Georgia in America under a charter issued by King George II.
The Trustees implemented an elaborate plan for the colony's settlement, known as the Oglethorpe Plan, which envisioned an agrarian society of yeoman farmers and prohibited slavery. The colony was invaded by the Spanish during the War of Jenkins' Ear. In 1752, after the government failed to renew subsidies that had helped support the colony, the Trustees turned over control to the crown. Georgia became a crown colony, with a governor appointed by the king; the Province of Georgia was one of the Thirteen Colonies that revolted against British rule in the American Revolution by signing the 1776 Declaration of Independence. The State of Georgia's first constitution was ratified in February 1777. Georgia was the 10th state to ratify the Articles of Confederation on July 24, 1778, was the 4th state to ratify the United States Constitution on January 2, 1788. In 1829, gold was discovered in the North Georgia mountains leading to the Georgia Gold Rush and establishment of a federal mint in Dahlonega, which continued in operation until 1861.
The resulting influx of white settlers put pressure on the government to take land from the Cherokee Nation. In 1830, President Andrew Jackson signed the Indian Removal Act, sending many eastern Native American nations to reservations in present-day Oklahoma, including all of Georgia's tribes. Despite the Supreme Court's ruling in Worcester v. Georgia that U. S. states were not permitted to redraw Indian boundaries, President Jackson and the state of Georgia ignored the ruling. In 1838, his successor, Martin Van Buren, dispatched federal troops to gather the tribes and deport them west of the Mississippi; this forced relocation, known as the Trail of Tears, led to the death of over 4,000 Cherokees. In early 1861, Georgia became a major theater of the Civil War. Major battles took place at Chickamauga, Kennesaw Mountain, Atlanta. In December 1864, a large swath of the state from Atlanta to Savannah was destroyed during General William Tecumseh Sherman's March to the Sea. 18,253 Georgian soldiers died in service one of every five who served.
In 1870, following the Reconstruction Era, Georgia became the last Confederate state to be restored to the Union. With white Democrats having regained power in the state legislature, they passed a poll tax in 1877, which disenfranchised many poor blacks and whites, preventing them from registering. In 1908, the state established a white primary, they constituted 46.7% of the state's population in 1900, but the proportion of Georgia's population, African American dropped thereafter to 28% due to tens of thousands leaving the state during the Great Migration. According to the Equal Justice Institute's 2015 report on lynching in the United States, Georgia had 531 deaths, the second-highest total of these extralegal executions of any state in the South; the overwhelming number of victims were male. Political disfranchisement persisted through the mid-1960s, until after Congress passed the Voting Rights Act of 1965. An Atlanta-born Baptist minister, part of the educated middle class that had developed in Atlanta's African-American community, Martin Luther King, Jr. emerged as a national leader in the civil rights movement.
King joining with others to form the Southern Christian Leadership Conference in Atlanta in 1957 to provide political leadership for the Civil Rights Movement across the South. By the 1960s, the proportion of
Washington, D. C. formally the District of Columbia and referred to as Washington or D. C. is the capital of the United States. Founded after the American Revolution as the seat of government of the newly independent country, Washington was named after George Washington, first President of the United States and Founding Father; as the seat of the United States federal government and several international organizations, Washington is an important world political capital. The city is one of the most visited cities in the world, with more than 20 million tourists annually; the signing of the Residence Act on July 16, 1790, approved the creation of a capital district located along the Potomac River on the country's East Coast. The U. S. Constitution provided for a federal district under the exclusive jurisdiction of the U. S. Congress, the District is therefore not a part of any state; the states of Maryland and Virginia each donated land to form the federal district, which included the pre-existing settlements of Georgetown and Alexandria.
The City of Washington was founded in 1791 to serve as the new national capital. In 1846, Congress returned the land ceded by Virginia. Washington had an estimated population of 702,455 as of July 2018, making it the 20th most populous city in the United States. Commuters from the surrounding Maryland and Virginia suburbs raise the city's daytime population to more than one million during the workweek. Washington's metropolitan area, the country's sixth largest, had a 2017 estimated population of 6.2 million residents. All three branches of the U. S. federal government are centered in the District: Congress and the U. S. Supreme Court. Washington is home to many national monuments, museums situated on or around the National Mall; the city hosts 177 foreign embassies as well as the headquarters of many international organizations, trade unions, non-profit, lobbying groups, professional associations, including the World Bank Group, the International Monetary Fund, the Organization of American States, AARP, the National Geographic Society, the Human Rights Campaign, the International Finance Corporation, the American Red Cross.
A locally elected mayor and a 13‑member council have governed the District since 1973. However, Congress may overturn local laws. D. C. residents elect a non-voting, at-large congressional delegate to the House of Representatives, but the District has no representation in the Senate. The District receives three electoral votes in presidential elections as permitted by the Twenty-third Amendment to the United States Constitution, ratified in 1961. Various tribes of the Algonquian-speaking Piscataway people inhabited the lands around the Potomac River when Europeans first visited the area in the early 17th century. One group known as the Nacotchtank maintained settlements around the Anacostia River within the present-day District of Columbia. Conflicts with European colonists and neighboring tribes forced the relocation of the Piscataway people, some of whom established a new settlement in 1699 near Point of Rocks, Maryland. In his Federalist No. 43, published January 23, 1788, James Madison argued that the new federal government would need authority over a national capital to provide for its own maintenance and safety.
Five years earlier, a band of unpaid soldiers besieged Congress while its members were meeting in Philadelphia. Known as the Pennsylvania Mutiny of 1783, the event emphasized the need for the national government not to rely on any state for its own security. Article One, Section Eight, of the Constitution permits the establishment of a "District as may, by cession of particular states, the acceptance of Congress, become the seat of the government of the United States". However, the Constitution does not specify a location for the capital. In what is now known as the Compromise of 1790, Alexander Hamilton, Thomas Jefferson came to an agreement that the federal government would pay each state's remaining Revolutionary War debts in exchange for establishing the new national capital in the southern United States. On July 9, 1790, Congress passed the Residence Act, which approved the creation of a national capital on the Potomac River; the exact location was to be selected by President George Washington, who signed the bill into law on July 16.
Formed from land donated by the states of Maryland and Virginia, the initial shape of the federal district was a square measuring 10 miles on each side, totaling 100 square miles. Two pre-existing settlements were included in the territory: the port of Georgetown, founded in 1751, the city of Alexandria, founded in 1749. During 1791–92, Andrew Ellicott and several assistants, including a free African American astronomer named Benjamin Banneker, surveyed the borders of the federal district and placed boundary stones at every mile point. Many of the stones are still standing. A new federal city was constructed on the north bank of the Potomac, to the east of Georgetown. On September 9, 1791, the three commissioners overseeing the capital's construction named the city in honor of President Washington; the federal district was named Columbia, a poetic name for the United States in use at that time. Congress held its first session in Washington on November 17, 1800. Congress passed the District of Columbia Organic Act of 1801 that organized the District and placed the entire territory under the exclusive control of the federal
Atlanta is the capital of, the most populous city in, the U. S. state of Georgia. With an estimated 2017 population of 486,290, it is the 38th most-populous city in the United States; the city serves as the cultural and economic center of the Atlanta metropolitan area, home to 5.8 million people and the ninth-largest metropolitan area in the nation. Atlanta is the seat of the most populous county in Georgia. A small portion of the city extends eastward into neighboring DeKalb County. Atlanta was founded as the terminating stop of a major state-sponsored railroad. With rapid expansion, however, it soon became the convergence point between multiple railroads, spurring its rapid growth; the city's name derives from that of the Western and Atlantic Railroad's local depot, signifying the town's growing reputation as a transportation hub. During the American Civil War, the city was entirely burned to the ground in General William T. Sherman's famous March to the Sea. However, the city rose from its ashes and became a national center of commerce and the unofficial capital of the "New South".
During the 1950s and 1960s, Atlanta became a major organizing center of the civil rights movement, with Dr. Martin Luther King Jr. Ralph David Abernathy, many other locals playing major roles in the movement's leadership. During the modern era, Atlanta has attained international prominence as a major air transportation hub, with Hartsfield–Jackson Atlanta International Airport being the world's busiest airport by passenger traffic since 1998. Atlanta is rated as a "beta" world city that exerts a moderate impact on global commerce, research, education, media and entertainment, it ranks in the top twenty among world cities and 10th in the nation with a gross domestic product of $385 billion. Atlanta's economy is considered diverse, with dominant sectors that include transportation, logistics and business services, media operations, medical services, information technology. Atlanta has topographic features that include rolling hills and dense tree coverage, earning it the nickname of "the city in a forest."
Revitalization of Atlanta's neighborhoods spurred by the 1996 Summer Olympics, has intensified in the 21st century, altering the city's demographics, politics and culture. Prior to the arrival of European settlers in north Georgia, Creek Indians inhabited the area. Standing Peachtree, a Creek village where Peachtree Creek flows into the Chattahoochee River, was the closest Indian settlement to what is now Atlanta; as part of the systematic removal of Native Americans from northern Georgia from 1802 to 1825, the Creek were forced to leave the area in 1821, white settlers arrived the following year. In 1836, the Georgia General Assembly voted to build the Western and Atlantic Railroad in order to provide a link between the port of Savannah and the Midwest; the initial route was to run southward from Chattanooga to a terminus east of the Chattahoochee River, which would be linked to Savannah. After engineers surveyed various possible locations for the terminus, the "zero milepost" was driven into the ground in what is now Five Points.
A year the area around the milepost had developed into a settlement, first known as "Terminus", as "Thrasherville" after a local merchant who built homes and a general store in the area. By 1842, the town had six buildings and 30 residents and was renamed "Marthasville" to honor the Governor's daughter. J. Edgar Thomson, Chief Engineer of the Georgia Railroad, suggested the town be renamed Atlanta; the residents approved, the town was incorporated as Atlanta on December 29, 1847. By 1860, Atlanta's population had grown to 9,554. During the American Civil War, the nexus of multiple railroads in Atlanta made the city a hub for the distribution of military supplies. In 1864, the Union Army moved southward following the capture of Chattanooga and began its invasion of north Georgia; the region surrounding Atlanta was the location of several major army battles, culminating with the Battle of Atlanta and a four-month-long siege of the city by the Union Army under the command of General William Tecumseh Sherman.
On September 1, 1864, Confederate General John Bell Hood made the decision to retreat from Atlanta, he ordered the destruction of all public buildings and possible assets that could be of use to the Union Army. On the next day, Mayor James Calhoun surrendered Atlanta to the Union Army, on September 7, Sherman ordered the city's civilian population to evacuate. On November 11, 1864, Sherman prepared for the Union Army's March to the Sea by ordering the destruction of Atlanta's remaining military assets. After the Civil War ended in 1865, Atlanta was rebuilt. Due to the city's superior rail transportation network, the state capital was moved from Milledgeville to Atlanta in 1868. In the 1880 Census, Atlanta surpassed Savannah as Georgia's largest city. Beginning in the 1880s, Henry W. Grady, the editor of the Atlanta Constitution newspaper, promoted Atlanta to potential investors as a city of the "New South" that would be based upon a modern economy and less reliant on agriculture. By 1885, the founding of the Georgia School of Technology and the Atlanta University Center had established Atlanta as a center for higher education.
In 1895, Atlanta hosted the Cotton States and International Exposition, which attracted nearly 800,000 attendees and promoted the New South's development to the world. During the first decades of the 20th century, Atlanta experienced a period of unprecedented growth. In three decades' time, Atlanta's population tripled as the city limits expanded to include nearby streetcar suburbs; the city's skyline emerged with the construction of the
A turboprop engine is a turbine engine that drives an aircraft propeller. In its simplest form a turboprop consists of an intake, combustor, a propelling nozzle. Air is compressed by the compressor. Fuel is added to the compressed air in the combustor, where the fuel-air mixture combusts; the hot combustion gases expand through the turbine. Some of the power generated by the turbine is used to drive the compressor; the rest is transmitted through the reduction gearing to the propeller. Further expansion of the gases occurs in the propelling nozzle, where the gases exhaust to atmospheric pressure; the propelling nozzle provides a small proportion of the thrust generated by a turboprop. In contrast to a turbojet, the engine's exhaust gases do not contain enough energy to create significant thrust, since all of the engine's power is used to drive the propeller. Exhaust thrust in a turboprop is sacrificed in favour of shaft power, obtained by extracting additional power from turbine expansion. Owing to the additional expansion in the turbine system, the residual energy in the exhaust jet is low.
The exhaust jet produces around or less than 10% of the total thrust. A higher proportion of the thrust comes from less at higher speeds. Turboprops can have bypass ratios up to 50-100 although the propulsion airflow is less defined for propellers than for fans; the propeller is coupled to the turbine through a reduction gear that converts the high RPM/low torque output to low RPM/high torque. The propeller itself is a constant speed type similar to that used with larger reciprocating aircraft engines. Unlike the small diameter fans used in turbofan jet engines, the propeller has a large diameter that lets it accelerate a large volume of air; this permits a lower airstream velocity for a given amount of thrust. As it is more efficient at low speeds to accelerate a large amount of air by a small degree than a small amount of air by a large degree, a low disc loading increases the aircraft's energy efficiency, this reduces the fuel use. Propellers lose efficiency as aircraft speed increases, so turboprops are not used on high-speed aircraft above Mach 0.6-0.7.
However, propfan engines, which are similar to turboprop engines, can cruise at flight speeds approaching Mach 0.75. To increase propeller efficiency, a mechanism can be used to alter their pitch relative to the airspeed. A variable-pitch propeller called a controllable-pitch propeller, can be used to generate negative thrust while decelerating on the runway. Additionally, in the event of an engine failure, the pitch can be adjusted to a vaning pitch, thus minimizing the drag of the non-functioning propeller. While most modern turbojet and turbofan engines use axial-flow compressors, turboprop engines contain at least one stage of centrifugal compression. Centrifugal compressors have the advantage of being simple and lightweight, at the expense of a streamlined shape. While the power turbine may be integral with the gas generator section, many turboprops today feature a free power turbine on a separate coaxial shaft; this enables the propeller to rotate independent of compressor speed. Residual thrust on a turboshaft is avoided by further expansion in the turbine system and/or truncating and turning the exhaust 180 degrees, to produce two opposing jets.
Apart from the above, there is little difference between a turboprop and a turboshaft. Alan Arnold Griffith had published a paper on turbine design in 1926. Subsequent work at the Royal Aircraft Establishment investigated axial turbine designs that could be used to supply power to a shaft and thence a propeller. From 1929, Frank Whittle began work on centrifugal turbine designs that would deliver pure jet thrust; the world's first turboprop was designed by the Hungarian mechanical engineer György Jendrassik. Jendrassik published a turboprop idea in 1928, on 12 March 1929 he patented his invention. In 1938, he built a small-scale experimental gas turbine; the larger Jendrassik Cs-1, with a predicted output of 1,000 bhp, was produced and tested at the Ganz Works in Budapest between 1937 and 1941. It was of axial-flow design with 15 compressor and 7 turbine stages, annular combustion chamber and many other modern features. First run in 1940, combustion problems limited its output to 400 bhp. In 1941,the engine was abandoned due to war, the factory was turned over to conventional engine production.
The world's first turboprop engine that went into mass production was designed by a German engineer, Max Adolf Mueller, in 1942. The first mention of turboprop engines in the general public press was in the February 1944 issue of the British aviation publication Flight, which included a detailed cutaway drawing of what a possible future turboprop engine could look like; the drawing was close to what the future Rolls-Royce Trent would look like. The first British turboprop engine was the Rolls-Royce RB.50 Trent, a converted Derwent II fitted with reduction gear and a Rotol 7 ft 11 in five-bladed propeller. Two Trents were fitted to Gloster Meteor EE227 — the sole "Trent-Meteor" — which thus became the world's first turboprop-powered aircraft, albeit a test-bed not intended for production, it first flew on 20 September 1945. From their experience with the Trent, Rolls-Royce developed the Rolls-Royce Clyde, the first turboprop engine to be type certificated for military and civil use, the Dart, which became one of the most reliable turboprop engines built.
Dart production continued for more than fifty years. The Dart-powered Vickers Vi