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57-701: The Miles M.25 Martinet was a target tug aircraft of the Royal Air Force (RAF) and Fleet Air Arm (FAA) that was in service during the Second World War . It was the first British aircraft to be designed specifically for target towing. Work on the Martinet was started in response to the RAF's shortage of obsolete frontline aircraft for target towing duties. A derivative of the Master trainer, it

114-518: A Hungarian fighter-bomber of WWII which had one model completed, but before its first flight it was destroyed in 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

171-438: A derivative of the Martinet that functioned as a radio-controlled target drone to meet Specification Q.10/43 . This variant, designated M.50 Queen Martinet , was quickly prototyped and a modest production contact was issued to Miles, leading to 69 examples being manufactured as a new-builds, while a further 17 aircraft were produced via the conversion of production Martinets. During its development and initial years of operation,

228-480: A detailed cutaway drawing of what a possible future turboprop engine could look like. The drawing was very 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 (2.41 m) five-bladed propeller. Two Trents were fitted to Gloster Meteor EE227 —

285-418: 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 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

342-467: 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, 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

399-482: A more heavy-duty cooling system was also installed to aid the engine in coping with the greater power output needed to offset the elevated drag that was induced while towing. Numerous RAF units received Martinets during the Second World War. Specifically, the type became a staple of air gunnery schools, operational training units, anti-aircraft cooperation squadrons, and air-sea reconnaissance units. During

456-577: 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. 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

513-537: 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 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

570-464: A relatively high degree of commonality, particularly in terms of components, there were also major differences, including the strengthening of the airframe to better handle the stresses of towing a target drogue. Other differences from the Master included a longer nose, greater wingspan, and higher cockpit, while the dual flying controls of the Master were omitted as unnecessary in its new capacity. Both

627-550: A relatively secret aircraft in response to Specification Q.10/43 , which called for a radio-controlled target drone . This aircraft, designated the M.50 Queen Martinet , was only produced in small numbers, and its existence was a state secret until 1946. Several other derivatives of the basic airframe were also produced, including a dedicated glider tug and a trainer variant. Before 1941, the target tug role had been met by reusing former frontline aircraft which had either become obsolete or were surplus to requirements. However, while

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684-462: A ship of the Taiwanese Navy during a live-fire exercise . All four occupants were killed. Turboprop A turboprop is a turbine engine that drives an aircraft propeller . A turboprop consists of an intake , reduction gearbox , compressor , combustor , turbine , and a propelling nozzle . Air enters the intake and is compressed by the compressor. Fuel is then added to

741-719: A specialised target tug aircraft based upon the Miles Master trainer aircraft. The requirements were formalised by the Ministry as Specification 12/41 . Amongst the listed requirements was a stipulation that, in order simplify manufacturing as much as possible, the envisioned aircraft ought maximise the use of standardised components wherever feasible. On 24 April 1942, the first prototype Martinet made its maiden flight from Woodley Aerodrome , flown by chief test pilot Flight Lieutenant Thomas Rose . Results were satisfactory enough for production to begin immediately, leading to

798-415: 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 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

855-418: 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 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

912-410: Is distinguished from the reciprocating engine constant-speed propeller by the control system. The turboprop system consists of 3 propeller governors , 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

969-705: Is owned by the Museum of Berkshire Aviation in the United Kingdom. The aircraft (RAF serial number MS902 ) was built in 1943, and spent its operational life in Iceland at RAF Reykjavik . In 1949, MS902 was sold to the Akureyri Flying Club and given the Icelandic civil registration TF-SHC . The club flew it until it crashed in 1951 near Kopasker in north-east Iceland. The wreckage remained at

1026-440: 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 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

1083-558: The Hawker Sea Fury , Fairey Firefly and Douglas Skyraider . Many air arms however continued to operate target tugs on their own behalf. In later years the use of civilian companies expanded significantly worldwide, with many companies forming or entering the field in the 1960s and 1970s. The trend was still to use ex-military aircraft, for example Fawcett Aviation in Australia used two ex- RAAF CAC Mustangs from 1960 until

1140-634: 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

1197-841: 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

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1254-453: 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 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

1311-563: The TBD Devastator as target tugs. The Luftwaffe and the VVS (Red Army) also used tugs. The chief modifications to the aircraft were a station for the drogue operator and a winch to reel in the cable prior to landing. The winch was typically powered by a small wind turbine on the outside of the aircraft, driven by the airflow and attached to the winch via a clutch . Such devices are still used by some aerial refueling tankers to retract

1368-614: 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,

1425-620: The UK and associated companies AVdef (in France ) and Falcon Special Air Services (in Malaysia ) using Falcon 20s ; Pel-Air in Australia using Learjets and (in something of a reversal of recent trends) EIS Aircraft Gmbh in Germany using Pilatus PC-9 aircraft. Target towing operations are not without risk. On September 17, 1994 a Golden Eagle Aviation Lear 35A was accidentally shot down by

1482-498: The air arms on behalf of which they flew, and were usually conversions of aircraft that had failed in combat or that were otherwise unsuitable or obsolete in their design roles (see Fairey Battle and Short Sturgeon ). These aircraft typically trailed a drogue fabric sleeve at the end of a several-thousand metre long cable. Student fighter pilots or air gunners would shoot at the target from other aircraft using painted bullets so that hits could be recorded and later analysed. In

1539-640: The airshow circuit or under restoration to fly, and in aviation museums. Today, more air arms have turned to civilian companies for provision of target towing services. Many companies operating in this field today do so using modified corporate jet aircraft instead of ex-military aircraft. Advantages of operating civil aircraft types include ease of registration (it being difficult in many countries to register ex-military jets as civil aircraft), ease of maintenance and lower operating costs when compared to ex-military aircraft. Companies active in 2007 providing target towing services include FR Aviation Services Ltd. in

1596-463: The Martinet rapidly supplanting the Master II on Miles' assembly lines at Woodley. In total 1,724 Martinets were produced; the majority of which served with either the RAF or Fleet Air Arm (FAA), although a minority of the type were adopted by overseas operators as well during the post war era. The Martinet became the basis for further projects by the company. During 1943, it was decided to produce

1653-910: The RAF, Miles Master IIs were used for this purpose as part of the Target Towing Flight at the Central Gunnery School whilst the School was based at RAF Sutton Bridge from April 1942 to March 1944. Other aircraft used in this role were the Hawker Henley , the Boulton Paul Defiant and the Westland Lysander , although the RAF was by no means the only air arm to use target tugs. They were used by most air forces. The USAAF used older aircraft such as

1710-533: 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

1767-482: 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 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

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1824-725: The crash site until 1977, when it was recovered and placed in storage by the Icelandic Aviation Historical Society. The aircraft was returned to the United Kingdom in 1996 by the Museum of Berkshire Aviation and has since been the subject of a lengthy restoration project. Data from Miles Aircraft since 1925 , The Hamlyn Concise Guide to British Aircraft of World War II. General characteristics Performance Related development Related lists Target tug Prior to and during World War II target tugs were typically operated by

1881-464: The crucial Battle of Britain was being waged and attrition rates were driven high amongst either side, the RAF found itself with a shortage of frontline aircraft. Seeking to avoid withdrawing existing combat-capable aircraft to perform as target tugs, the Air Ministry opted to procure new build aircraft specifically for this need, approaching Miles Aircraft Ltd with a request to rapidly produce

1938-551: 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 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

1995-409: The drogue could be jettisoned (see Hawker Henley ). The use of such aircraft continued post-war, although a trend developed whereby ex-military aircraft were purchased, modified and operated by civilian companies under contract. Deutsche-Luftfahrt Beratungsdienst of West Germany and Svensk Flygtjänst AB of Sweden were two notable companies in the field in the post-war years, operating such types as

2052-426: 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 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

2109-402: 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 the additional expansion in the turbine system, the residual energy in the exhaust jet is low. Consequently, the exhaust jet produces about 10% of

2166-682: The existence of the Queen Martinet was classified and the programme was held on the UK Government's Secrets List ; it was first publicly displayed at the Farnborough Airshow in June 1946, although details about the type remained protected for a number of years thereafter. By 1941, officials were considered a proposed improved model of the Master trainer, but such ambitions were sidelined to focus manufacturing resources on

2223-499: 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

2280-564: 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

2337-467: 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 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

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2394-660: The late 1940s and early 1950s, the type was gradually withdrawn from service within Britain's armed forces. A total of five former RAF Martinets received civil registrations and were flown by civilians both in Britain and overseas. Efforts were made to promote surplus Martinet to fulfil additional roles, one such proposal involved the type's adoption by the Royal Hellenic Air Force to perform missions such as artillery spotting, general observation, and close air support . Data from: A single Martinet survives; it

2451-744: The latter part of the 1970s. Flight Systems Inc. commenced operations at Mojave, California with Canadair Sabres converted as QF-86E missile targets, the first aircraft making its first unmanned flight in April 1975; this company later also operated Sabres as target tugs. Flight Systems Inc was later purchased by Tracor and these operations are still performed by BAE Systems Flight Systems with Douglas Skyhawks . The practice of using ex-military aircraft as target tugs (and of air arms retaining older aircraft themselves for such use) resulted in them surviving into an era where such aircraft became desirable as Warbirds ; many former target tugs are now to be found on

2508-671: 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

2565-450: 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 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

2622-402: The refueling hose after the operation is completed. The drogue would often be jettisoned at some location convenient for recovery prior to the aircraft's landing. The drogue itself caused a great deal of drag and could be dangerous, particularly to less-powerful aircraft. If the engine failed, the drag from the drogue could be enough to reduce the airspeed of the aircraft below stall speed before

2679-505: The removal of the outboard wing fuel tanks, the installation of a revised cabin with dual controls fitted, and a reduction in overall weight. A pair of prototypes were built, the first of which made its maiden flight on 11 April 1946. However, by the time it was ready for quantity production, more advanced trainers, such as the Avro Athena and Boulton Paul Balliol , had also reached an advanced stage of development, leaving no purpose for

2736-592: 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

2793-698: The sole "Trent-Meteor" — which thus became the world's first turboprop-powered aircraft to fly, albeit as 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

2850-473: 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 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

2907-466: The standard Martinet model. By 1945, production pressures had alleviated to the point where serious work could commence, thus Miles set about developing a trainer model of the aircraft, designated M.37 Martinet Trainer . From the onset, this aircraft was intended to be a stopgap measure as the Air Ministry had envisioned its long term trainer to harness turboprop propulsion. The conversion involved

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2964-412: The targets and towing gear were contained in a fairing beneath the fuselage, which could be deployed and retracted by a winch ; multiple implementations of this apparatus were used, including winches that were alternatively driven via electric motors or wind power. Due to the aircraft's centre of gravity being altered by the design modifications, the engine was brought forwards slightly to compensate; while

3021-493: 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 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

3078-476: The type and thus it received no orders. A more numerous variant of the Martinet was the adaption of the type for operating as a tug for gliders ; it shared broad similarities to the Master II tug, the rudder having its lower portion removed along with the installation of stronger towing apparatus. The Miles Martinet draws heavily upon the Miles Master II trainer aircraft. While the two aircraft shared

3135-405: Was designed to have as much commonality with existing production aircraft as possible. The first prototype Martinet made its maiden flight on 24 April 1942; quantity production started immediately. A total of 1,724 Martinets were produced, of which the majority were operated either by the RAF or FAA, although some were used by overseas and civilian operators. The Martinet was also developed into

3192-714: 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

3249-603: 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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