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60-652: The Aero Commander 500 family is a series of light-twin piston-engined and turboprop aircraft originally built by the Aero Design and Engineering Company in the late 1940s, renamed the Aero Commander company in 1950, and later a division of Rockwell International in 1965. Final production occurred under the Gulfstream Aerospace name. The initial production version was the 200 mph (320 km/h; 170 kn), seven-seat Aero Commander 520 . An improved version,

120-400: A Pratt & Whitney Canada PT6 , and an under-speed governor on a Honeywell TPE331 . The turboprop is also distinguished from other kinds of turbine engine in that the fuel control unit is connected to the governor to help dictate power. To make the engine more compact, reverse airflow can be used. On a reverse-flow turboprop engine, the compressor intake is at the aft of the engine, and

180-424: A propelling nozzle . Air enters the intake and is compressed by the compressor. Fuel is then added to the compressed air in the combustor, where the fuel-air mixture then combusts . The hot combustion gases expand through the turbine stages, generating power at the point of exhaust. Some of the power generated by the turbine is used to drive the compressor and electric generator . The gases are then exhausted from

240-605: A Bob Hoover tribute routine. One U-4B became a presidential transport aircraft for Dwight D. Eisenhower between 1956 and 1960. This was the smallest " Air Force One ", and the first to wear the now-familiar blue-and-white livery. This aircraft is now owned by the Commemorative Air Force . As of 2004 Shrike Commanders remained in service with the United States Customs Service , United States Coast Guard , and United States Forest Service . A single 560F

300-510: A bombing raid. In 1941, the engine was abandoned due to war, and the factory converted to conventional engine production. 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 very close to what

360-442: A governor, and overspeed governor, and a fuel-topping governor. The governor works in much the same way a reciprocating engine propeller governor works, though a turboprop governor may incorporate beta control valve or beta lift rod for beta operation and is typically located in the 12 o'clock position. There are also other governors that are included in addition depending on the model, such as an overspeed and fuel topping governor on

420-410: A mode typically consisting of zero to negative thrust, is used for all ground operations aside from takeoff. The Beta mode is further broken down into 2 additional modes, Beta for taxi and Beta plus power. Beta for taxi as the name implies is used for taxi operations and consists of all pitch ranges from the lowest alpha range pitch, all the way down to zero pitch, producing very little to zero-thrust and

480-451: A number of federal law enforcement officers throughout the 19th and 20th centuries. Customs Special Agents investigated smuggling and other violations of customs, narcotics and revenue laws. Customs Inspectors were uniformed officers at airports, seaports and land border ports of entry who inspected people and vehicles entering the U.S. for contraband and dutiable merchandise. Customs Patrol Officers conducted uniformed and plainclothes patrol of

540-465: A single, unified border agency for the U.S. The investigative office of U.S. Customs was split off and merged with the INS investigative office and the INS interior detention and removal office to form Immigration and Customs Enforcement , which, among other things, is responsible for interior immigration enforcement. The United States Customs Service had three major missions: collecting tariff revenue, protecting

600-581: A small amount of air by a large degree, a low disc loading (thrust per unit disc area) increases the aircraft's energy efficiency , and this reduces the fuel use. Propellers work well until the flight speed of the aircraft is high enough that the airflow past the blade tips reaches the speed of sound. Beyond that speed, the proportion of the power that drives the propeller that is converted to propeller thrust falls dramatically. For this reason turboprop engines are not commonly used on aircraft that fly faster than 0.6–0.7 Mach , with some exceptions such as

660-575: 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 receive a type certificate for military and civil use, and the Dart , which became one of the most reliable turboprop engines ever built. Dart production continued for more than fifty years. The Dart-powered Vickers Viscount

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720-485: Is coupled to the turbine through a reduction gear that converts the high RPM /low torque output to low RPM/high torque. This can be of two primary designs, free-turbine and fixed. A free-turbine turboshaft found on the Pratt & Whitney Canada PT6 , where the gas generator is not connected to the propeller. This allows for propeller strike or similar damage to occur without damaging the gas generator and allowing for only

780-407: Is that it can also be used to generate reverse thrust to reduce stopping distance on the runway. Additionally, in the event of an engine failure, the propeller can be feathered , thus minimizing the drag of the non-functioning propeller. 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

840-421: Is typically accessed by moving the power lever to a beta for taxi range. Beta plus power is a reverse range and produces negative thrust, often used for landing on short runways where the aircraft would need to rapidly slow down, as well as backing operations and is accessed by moving the power lever below the beta for taxi range. Due to the pilot not being able to see out of the rear of the aircraft for backing and

900-639: The 500S , manufactured after 1967, is known as the Shrike Commander . Larger variants are known by numerous model names and designations, ranging up to the 330 mph (530 km/h; 290 kn), 11-seat Model 695B/Jetprop 1000B turboprop. As of recent, the Aero Commander is known as the Twin Commander. The idea for the Commander light business twin was conceived by Ted Smith , a project engineer at

960-547: The Douglas Aircraft Company . Working part-time after hours throughout 1944, a group of A-20 engineers formed the Aero Design and Engineering Company to design and build the proposed aircraft with a layout similar to their A-20 bomber. Originally, the new company was going to build three pre-production aircraft, but as the first aircraft was being built, they decided to build just one prototype. The final configuration

1020-547: The Federal Bureau of Investigation , U.S. Postal Inspection Service , U.S. Immigration and Naturalization Service and U.S. Border Patrol —to investigate cases often far from international airports, bridges and land crossings. The original World Trade Center complex, Building 6 , housed offices of the U.S. Customs Service. With the passage of the Homeland Security Act , the U.S. Customs Service passed from under

1080-616: The P-3 Orion , and the C-130 Hercules military transport aircraft. The first turbine-powered, shaft-driven helicopter was the Kaman K-225 , a development of Charles Kaman 's K-125 synchropter , which used a Boeing T50 turboshaft engine to power it on 11 December 1951. December 1963 saw the first delivery of Pratt & Whitney Canada's PT6 turboprop engine for the then Beechcraft 87, soon to become Beechcraft King Air . 1964 saw

1140-830: The Piper Meridian , Socata TBM , Pilatus PC-12 , Piaggio P.180 Avanti , Beechcraft King Air and Super King Air . In April 2017, there were 14,311 business turboprops in the worldwide fleet. Between 2012 and 2016, the ATSB observed 417 events with turboprop aircraft, 83 per year, over 1.4 million flight hours: 2.2 per 10,000 hours. Three were "high risk" involving engine malfunction and unplanned landing in single‑engine Cessna 208 Caravans , four "medium risk" and 96% "low risk". Two occurrences resulted in minor injuries due to engine malfunction and terrain collision in agricultural aircraft and five accidents involved aerial work: four in agriculture and one in an air ambulance . Jane's All

1200-590: The Tupolev Tu-114 can reach 470 kn (870 km/h; 540 mph). Large military aircraft , like the Tupolev Tu-95 , and civil aircraft , such as the Lockheed L-188 Electra , were also turboprop powered. The Airbus A400M is powered by four Europrop TP400 engines, which are the second most powerful turboprop engines ever produced, after the 11 MW (15,000 hp) Kuznetsov NK-12 . In 2017,

1260-403: The Tupolev Tu-95 . However, propfan engines, which are very similar to turboprop engines, can cruise at flight speeds approaching 0.75 Mach. To maintain propeller efficiency across a wide range of airspeeds, turboprops use constant-speed (variable-pitch) propellers. The blades of a constant-speed propeller increase their pitch as aircraft speed increases. Another benefit of this type of propeller

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1320-593: The U.S. economy from smuggling and illegal goods, and processing people and goods at ports of entry . Responding to the urgent need for revenue following the American Revolutionary War , the First United States Congress passed and President George Washington signed the Tariff Act of July 4, 1789, which authorized the collection of duties on imported goods. Four weeks later, on July 31,

1380-636: The critical engine , at that), then both engines out, and gliding. Then in his final airshow performance, in a supreme demonstration of conservation of momentum, he did all that, then landed the Shrike Commander dead stick (engines off), coasted the airplane down the runway then from the runway down the taxiway and silently let the craft roll slowly to a full stop right in front of the crowd. The turboprop twin-Commanders—with much more powerful engines (and most with longer bodies, allowing greater rudder leverage, critical for single-engine control) – came out on

1440-804: The Customs Service seal that was an eagle with three arrows in his left talon, an olive branch in his right and surrounded by an arc of 13 stars. In 1951, this was changed to the eagle depicted on the Great Seal of the United States . Its actual name is the Revenue Ensign , as it was flown by ships of the Revenue Cutter Service , later the Coast Guard , and at customs houses. In 1910, President William Howard Taft issued an order to add an emblem to

1500-516: The Shrike Commander 500S for decades in a variety of "managed energy" routines, including single-engine and engine-out aerobatics. His Shrike Commander is displayed in the colors of his last sponsor, Evergreen International Aviation , at the Steven F. Udvar-Hazy Center of the Smithsonian National Air and Space Museum . Bob Odegaard continued the tradition in 2012, flying a 1975 Shrike 500S in

1560-519: The Soviet Union had the technology to create the airframe for a jet-powered strategic bomber comparable to Boeing's B-52 Stratofortress , they instead produced the Tupolev Tu-95 Bear, powered with four Kuznetsov NK-12 turboprops, mated to eight contra-rotating propellers (two per nacelle) with supersonic tip speeds to achieve maximum cruise speeds in excess of 575 mph, faster than many of

1620-652: The World's Aircraft . 2005–2006. United States Customs Service In March 2003, as a result of the homeland security reorganization , the U.S. Customs Service was renamed the Bureau of Customs and Border Protection, and most of its components were merged with the border elements of the Immigration and Naturalization Service , including the entire U.S. Border Patrol and former INS inspectors, together with border agriculture inspectors, to form U.S. Customs and Border Protection ,

1680-420: The additional expansion in the turbine system, the residual energy in the exhaust jet is low. Consequently, the exhaust jet produces about 10% of the total thrust. A higher proportion of the thrust comes from the propeller at low speeds and less at higher speeds. Turboprops have bypass ratios of 50–100, although the propulsion airflow is less clearly defined for propellers than for fans. The propeller

1740-414: The amount of debris reverse stirs up, manufacturers will often limit the speeds beta plus power may be used and restrict its use on unimproved runways. Feathering of these propellers is performed by the propeller control lever. The constant-speed propeller is distinguished from the reciprocating engine constant-speed propeller by the control system. The turboprop system consists of 3 propeller governors ,

1800-455: The borders on land, sea and air to deter smuggling and apprehend smugglers. In the 20th century, as international trade and travel increased dramatically, the Customs Service transitioned from an administrative bureau to a federal law enforcement agency. Inspectors still inspected goods and took customs declarations from travelers at ports of entry, but Customs Special Agents used modern police methods—often in concert with allied agencies, such as

1860-464: The company leased, at no cost, a new 26,000 square feet (2,400 m) factory at Bethany near Oklahoma City to build a production version, certified on 30 June 1950. Nearly 10,000 hours of redesign work went into the model, including more powerful Lycoming GO-435-C2 engines, with a combined rating of 520 horsepower (390 kW). The production model was named the Commander 520 . The first Commander 520

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1920-570: The conventional manner. The flight received nationwide coverage in the press. In 1979, the National Transportation Safety Board reviewed light-twin engine-failure accidents, involving the 24 most popular model-groups of light twins between 1972 and 1976. They found that the piston -engined twin-Commanders had averaged slightly over 3.4 engine-failure accidents per hundred-thousand hours, the second worst number of all aircraft under review. The most engine failures were suffered by

1980-426: The developers were working to satisfy Civil Aeronautics Authority (CAA) regulations for certification of the 500, they chose a novel method of demonstrating its single-engine safety and performance: they removed one of the two-bladed propellers, secured it in the aft cabin, and flew from Bethany to Washington, D.C., on one engine. There they met with CAA personnel, then replaced the propeller and returned to Oklahoma in

2040-407: The exhaust is situated forward, reducing the distance between the turbine and the propeller. Unlike the small-diameter fans used in turbofan 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. Since it is more efficient at low speeds to accelerate a large amount of air by a small degree than

2100-601: The fifth act of Congress established the United States Customs Service and its ports of entry. As part of this new government agency, a new role was created for government officials which was known as "Customs Collector". In this role, one person would have responsibility to supervise the collection of custom duties in a particular city or region, such as the Collector of the Port of New York . For over 100 years after it

2160-493: The first jet aircraft and comparable to jet cruising speeds for most missions. The Bear would serve as their most successful long-range combat and surveillance aircraft and symbol of Soviet power projection through to the end of the 20th century. The USA used turboprop engines with contra-rotating propellers, such as the Allison T40 , on some experimental aircraft during the 1950s. The T40-powered Convair R3Y Tradewind flying-boat

2220-546: The first deliveries of the Garrett AiResearch TPE331 , (now owned by Honeywell Aerospace ) on the Mitsubishi MU-2 , making it the fastest turboprop aircraft for that year. In contrast to turbofans , turboprops are most efficient at flight speeds below 725 km/h (450 mph; 390 knots) because the jet velocity of the propeller (and exhaust) is relatively low. Modern turboprop airliners operate at nearly

2280-524: The first half of 2024. Beginning in June 1991, senior engineers met with FAA officials to discuss concerns over the Aero Commander's main wing spar, which was believed to be susceptible to stress fatigue and subsequent cracking, and was believed to have resulted in a number of fatal crashes. From approximately 1961 to 1993, 24 aircraft crashed when spar failures caused the loss of the wing in flight. 35 more spars were found cracked during inspections. In 1950, when

2340-501: The flag flown by ships from the one flown on land at customs houses. The version with the badge continues to be flown by Coast Guard vessels. Until 2003, the land version was flown at all United States ports of entry. The renamed CBP Ensign is currently flown at CBP's headquarters in Washington, D.C., at its Field Offices, overseas duty locations including preclearance ports, and at all land, air, and sea ports of entry. Beginning in 1927,

2400-458: 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 (2.41 m) 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 to fly, albeit as

2460-527: The investigative arms of the U.S. Customs Service and the Immigration and Naturalization Service, combined to form U.S. Immigration and Customs Enforcement . The flag of the Customs Service was designed in 1799 by Secretary of the Treasury Oliver Wolcott Jr. and consists of 16 vertical red and white stripes with a coat of arms depicted in blue on the white canton . The original design had

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2520-737: The jurisdiction of the Treasury Department to under the jurisdiction of the Department of Homeland Security . On March 1, 2003, parts of the U.S. Customs Service combined with the Inspections Program of the Immigration and Naturalization Service , Plant Protection and Quarantine of the USDA and the Border Patrol of the Immigration and Naturalization Service to form U.S. Customs and Border Protection . The Federal Protective Service , along with

2580-657: The most widespread turboprop airliners in service were the ATR 42 / 72 (950 aircraft), Bombardier Q400 (506), De Havilland Canada Dash 8 -100/200/300 (374), Beechcraft 1900 (328), de Havilland Canada DHC-6 Twin Otter (270), Saab 340 (225). Less widespread and older airliners include the BAe Jetstream 31 , Embraer EMB 120 Brasilia , Fairchild Swearingen Metroliner , Dornier 328 , Saab 2000 , Xian MA60 , MA600 and MA700 , Fokker 27 and 50 . Turboprop business aircraft include

2640-471: The opposite end of the rankings, with one of the lowest rates of engine-failure accidents of all "light" twins examined, at only 0.4 per hundred-thousand hours. Data from Jane's all the world's aircraft 1976–77. General characteristics Performance Turboprop A turboprop is a turbine engine that drives an aircraft propeller . A turboprop consists of an intake , reduction gearbox , compressor , combustor , turbine , and

2700-485: The power section (turbine and gearbox) to be removed and replaced in such an event, and also allows for less stress on the start during engine ground starts. Whereas a fixed shaft has the gearbox and gas generator connected, such as on the Honeywell TPE331 . The propeller itself is normally a constant-speed (variable pitch) propeller type similar to that used with larger aircraft reciprocating engines , except that

2760-522: The propeller to rotate freely, independent of compressor speed. Alan Arnold Griffith had published a paper on compressor design in 1926. Subsequent work at the Royal Aircraft Establishment investigated axial compressor-based designs that would drive a propeller. From 1929, Frank Whittle began work on centrifugal compressor-based designs that would use all the gas power produced by the engine for jet thrust. The world's first turboprop

2820-403: The propeller-control requirements are very different. Due to the turbine engine's slow response to power inputs, particularly at low speeds, the propeller has a greater range of selected travel in order to make rapid thrust changes, notably for taxi, reverse, and other ground operations. The propeller has 2 modes, Alpha and Beta. Alpha is the mode for all flight operations including takeoff. Beta,

2880-585: The same speed as small regional jet airliners but burn two-thirds of the fuel per passenger. Compared to piston engines, their greater power-to-weight ratio (which allows for shorter takeoffs) and reliability can offset their higher initial cost, maintenance and fuel consumption. As jet fuel can be easier to obtain than avgas in remote areas, turboprop-powered aircraft like the Cessna Caravan and Quest Kodiak are used as bush airplanes . Turboprop engines are generally used on small subsonic aircraft, but

2940-560: The small-engine versions of the Piper Apache , at 6.9 failures per hundred thousand hours; the third-worst, the Beechcraft Travel Air , averaged 2.9 failures; the average for all models was only 1.6. Countering the statistical evidence, Rockwell demonstration pilot Bob Hoover 's famous airshow stunt routine, with the Shrike Commander, included a full aerobatic routine performed first with both engines, then with one engine out (and

3000-415: The turbine. In contrast to a turbojet or turbofan , the engine's exhaust gases do not provide enough power to create significant thrust, since almost all of the engine's power is used to drive the propeller. Exhaust thrust in a turboprop is sacrificed in favor of shaft power, which is obtained by extracting additional power (beyond that necessary to drive the compressor) from turbine expansion. Owing to

3060-546: Was completed in July 1946 and was designated the Model L3805 . Registered NX1946 , the prototype first flew on 23 April 1948. The L3805 accommodated up to five people and was powered by two Lycoming O-435-A piston engines ., it was an all-metal high-wing monoplane with retractable undercarriage using components from a Vultee BT-13 Valiant . The market segment planned for this aircraft to be sold to small feeder airliner firms and

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3120-557: Was designed by the Hungarian mechanical engineer György Jendrassik . Jendrassik published a turboprop idea in 1928, and on 12 March 1929 he patented his invention. In 1938, he built a small-scale (100 Hp; 74.6 kW) 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

3180-623: Was founded, the U.S. Customs Service was the primary source of funds for the entire government, paying for the country's early growth and infrastructure. Purchases include the Louisiana and Oregon territories; Florida and Alaska ; funding the National Road and the Transcontinental Railroad ; building many of the nation's lighthouses ; the U.S. Military and Naval academies, and Washington, D.C. The U.S. Customs Service employed

3240-460: Was of axial-flow design with 15 compressor and 7 turbine stages, annular combustion chamber. First run in 1940, combustion problems limited its output to 400 bhp. Two Jendrassik Cs-1s were the engines for the world's first turboprop aircraft – the Varga RMI-1 X/H . This was a Hungarian fighter-bomber of WWII which had one model completed, but before its first flight it was destroyed in

3300-536: Was operated as a small package freighter by Combs Freightair in the 1970s and 1980s, and by Suburban Air Freight in the 1980s and 1990s. The aircraft was popular with pilots, because it was extremely "pilot friendly" and with its 380 hp (280 kW) supercharged engines did well in icing meteorological conditions. A number are still operated on contracts for cargo and fire control applications, as their piston engines offer good fuel specifics at low altitudes and longer loiter times. Suburban retired their last 680FLs in

3360-564: Was operated by the Belgian Air Force as the personal transport of the late king Baudouin of Belgium from 1961 to 1973. According to the July 1, 1968, Frontier Airlines system timetable, series 500 aircraft were being operated on scheduled passenger flights by Combs Aviation on behalf of Frontier via a contract agreement with service to several smaller communities in Montana and Wyoming at this time. The unpressurized, long-fuselage 680FL

3420-686: Was operated by the U.S. Navy for a short time. The first American turboprop engine was the General Electric XT31 , first used in the experimental Consolidated Vultee XP-81 . The XP-81 first flew in December 1945, the first aircraft to use a combination of turboprop and turbojet power. The technology of Allison's earlier T38 design evolved into the Allison T56 , used to power the Lockheed Electra airliner, its military maritime patrol derivative

3480-484: Was originally designed to carry seven passengers, but instead found use in the private business aircraft and military market. Walter Beech test flew the aircraft in 1949 and expressed interest in buying the project, but passed on it, to instead develop the Beechcraft Twin Bonanza . Fairchild Aircraft also evaluated the prototype at its Hagerstown, Maryland , headquarters. The prototype flew successfully and

3540-780: Was rolled out of the new factory in August 1951. Serial number 1 was used as a demonstrator, then sold in October 1952 to the Asahi Shimbun Press Company of Tokyo. In military service it was initially designated the L-26 , though in 1962 this was changed to U-4 for the United States Air Force and U-9 for the United States Army . Under ownership of Rockwell in the 1960s, World War II pilot R. A. "Bob" Hoover demonstrated

3600-593: Was the first turboprop aircraft of any kind to go into production and sold in large numbers. It was also the first four-engined turboprop. Its first flight was on 16 July 1948. The world's first single engined turboprop aircraft was the Armstrong Siddeley Mamba -powered Boulton Paul Balliol , which first flew on 24 March 1948. The Soviet Union built on German World War II turboprop preliminary design work by Junkers Motorenwerke, while BMW, Heinkel-Hirth and Daimler-Benz also worked on projected designs. While

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