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65-906: Lavochkin had produced a line of prop powered fighters in World War II. The Lavochkin La-150 was its first response to a 1945 order to build a single-seat jet fighter using a single German Junkers Jumo 004 turbojet from the Me 262 . The Lavochkin La-152 which flew in December 1946 moved the engine to the front of the nose, which reduced thrust loss. The Lavochkin La-160 was the first Soviet fighter to apply swept wings, and flew in June 1947. The Lavochkin La-168 first flew on April 22, 1948. It

130-416: A i r + m ˙ f ) V j − m ˙ a i r V {\displaystyle F_{N}=({\dot {m}}_{air}+{\dot {m}}_{f})V_{j}-{\dot {m}}_{air}V} where: If the speed of the jet is equal to sonic velocity the nozzle is said to be " choked ". If the nozzle is choked, the pressure at the nozzle exit plane

195-486: A "pod-and-boom" layout for their new fighter, based on advice from the Central Aerohydrodynamic Institute (TsAGI), although their design had a shoulder-mounted wing. The wings of the all-metal aircraft had fixed leading edges and slotted flaps . The cockpit was well forward, giving the pilot good visibility, and he was protected by an armored headrest. The windscreen of the teardrop-shaped canopy

260-450: A cramped cockpit without heating or ventilation, poor access to the engine, inadequate fuel capacity, compounded by the lack of a fuel gauge, and poor elevator control forces. Five aircraft were modified to correct these issues before resuming the factory's testing in late 1946. The modifications were not entirely successful and the lateral stability was now too great and the elevator forces remained too weak. Engine problems, however, plagued

325-580: A gas turbine to power an aircraft was filed in 1921 by Frenchman Maxime Guillaume . His engine was to be an axial-flow turbojet, but was never constructed, as it would have required considerable advances over the state of the art in compressors. In 1928, British RAF College Cranwell cadet Frank Whittle formally submitted his ideas for a turbojet to his superiors. In October 1929 he developed his ideas further. On 16 January 1930 in England, Whittle submitted his first patent (granted in 1932). The patent showed

390-542: A landing field, lengthening flights. The increase in reliability that came with the turbojet enabled three- and two-engine designs, and more direct long-distance flights. High-temperature alloys were a reverse salient , a key technology that dragged progress on jet engines. Non-UK jet engines built in the 1930s and 1940s had to be overhauled every 10 or 20 hours due to creep failure and other types of damage to blades. British engines, however, utilised Nimonic alloys which allowed extended use without overhaul, engines such as

455-454: A second generation SST engine using the 593 core were done more than three years before Concorde entered service. They evaluated bypass engines with bypass ratios between 0.1 and 1.0 to give improved take-off and cruising performance. Nevertheless, the 593 met all the requirements of the Concorde programme. Estimates made in 1964 for the Concorde design at Mach 2.2 showed the penalty in range for

520-411: A significant impact on commercial aviation . Aside from giving faster flight speeds turbojets had greater reliability than piston engines, with some models demonstrating dispatch reliability rating in excess of 99.9%. Pre-jet commercial aircraft were designed with as many as four engines in part because of concerns over in-flight failures. Overseas flight paths were plotted to keep planes within an hour of

585-405: A small helicopter engine compressor rotates around 50,000 RPM. Turbojets supply bleed air from the compressor to the aircraft for the operation of various sub-systems. Examples include the environmental control system , anti-icing , and fuel tank pressurization. The engine itself needs air at various pressures and flow rates to keep it running. This air comes from the compressor, and without it,

650-513: A turbojet application, where the output from the gas turbine is used in a propelling nozzle, raising the turbine temperature increases the jet velocity. At normal subsonic speeds this reduces the propulsive efficiency, giving an overall loss, as reflected by the higher fuel consumption, or SFC. However, for supersonic aircraft this can be beneficial, and is part of the reason why the Concorde employed turbojets. Turbojet systems are complex systems therefore to secure optimal function of such system, there

715-512: A turbojet engine is always subsonic, regardless of the speed of the aircraft itself. The intake has to supply air to the engine with an acceptably small variation in pressure (known as distortion) and having lost as little energy as possible on the way (known as pressure recovery). The ram pressure rise in the intake is the inlet's contribution to the propulsion system's overall pressure ratio and thermal efficiency . The intake gains prominence at high speeds when it generates more compression than

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780-494: A turbojet is high enough at higher thrust settings to cause the nozzle to choke. If, however, a convergent-divergent de Laval nozzle is fitted, the divergent (increasing flow area) section allows the gases to reach supersonic velocity within the divergent section. Additional thrust is generated by the higher resulting exhaust velocity. Thrust was most commonly increased in turbojets with water/methanol injection or afterburning . Some engines used both methods. Liquid injection

845-480: A two-stage axial compressor feeding a single-sided centrifugal compressor . Practical axial compressors were made possible by ideas from A.A. Griffith in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design"). Whittle later concentrated on the simpler centrifugal compressor only, for a variety of practical reasons. A Whittle engine was the first turbojet to run, the Power Jets WU , on 12 April 1937. It

910-413: Is a component of a turbojet used to divert air into the intake, in front of the accessory drive and to house the starter motor. An intake, or tube, is needed in front of the compressor to help direct the incoming air smoothly into the rotating compressor blades. Older engines had stationary vanes in front of the moving blades. These vanes also helped to direct the air onto the blades. The air flowing into

975-402: Is an airbreathing jet engine which is typically used in aircraft. It consists of a gas turbine with a propelling nozzle . The gas turbine has an air inlet which includes inlet guide vanes, a compressor, a combustion chamber, and a turbine (that drives the compressor). The compressed air from the compressor is heated by burning fuel in the combustion chamber and then allowed to expand through

1040-523: Is greater than atmospheric pressure, and extra terms must be added to the above equation to account for the pressure thrust. The rate of flow of fuel entering the engine is very small compared with the rate of flow of air. If the contribution of fuel to the nozzle gross thrust is ignored, the net thrust is: F N = m ˙ a i r ( V j − V ) {\displaystyle F_{N}={\dot {m}}_{air}(V_{j}-V)} The speed of

1105-568: Is modelled approximately by the Brayton cycle . The efficiency of a gas turbine is increased by raising the overall pressure ratio, requiring higher-temperature compressor materials, and raising the turbine entry temperature, requiring better turbine materials and/or improved vane/blade cooling. It is also increased by reducing the losses as the flow progresses from the intake to the propelling nozzle. These losses are quantified by compressor and turbine efficiencies and ducting pressure losses. When used in

1170-585: Is more commonly by use of a turboshaft engine, a development of the gas turbine engine where an additional turbine is used to drive a rotating output shaft. These are common in helicopters and hovercraft. Turbojets were widely used for early supersonic fighters , up to and including many third generation fighters , with the MiG-25 being the latest turbojet-powered fighter developed. As most fighters spend little time traveling supersonically, fourth-generation fighters (as well as some late third-generation fighters like

1235-662: The Izdeliye 150 – Aircraft or Article 150, USAF / DOD designation Type 3 ), was designed by the Lavochkin design bureau ( OKB ) in response to a 1945 order to build a single-seat jet fighter using a single German turbojet . By this time both the Americans and British, as well as the Germans, had already flown jet fighters and the single Soviet jet engine under development (the Lyulka TR-1 )

1300-613: The F-111 and Hawker Siddeley Harrier ) and subsequent designs are powered by the more efficient low-bypass turbofans and use afterburners to raise exhaust speed for bursts of supersonic travel. Turbojets were used on Concorde and the longer-range versions of the Tu-144 which were required to spend a long period travelling supersonically. Turbojets are still common in medium range cruise missiles , due to their high exhaust speed, small frontal area, and relative simplicity. The first patent for using

1365-679: The Gloster Meteor , entered service in 1944, towards the end of World War II , the Me 262 in April and the Gloster Meteor in July. Only about 15 Meteor saw WW2 action but up to 1400 Me 262s were produced, with 300 entering combat, delivering the first ground attacks and air combat victories of jet planes. Air is drawn into the rotating compressor via the intake and is compressed to a higher pressure before entering

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1430-571: The Heinkel HeS 3 ), or an axial compressor (as in the Junkers Jumo 004 ) which gave a smaller diameter, although longer, engine. By replacing the propeller used on piston engines with a high speed jet of exhaust, higher aircraft speeds were attainable. One of the last applications for a turbojet engine was Concorde which used the Olympus 593 engine. However, joint studies by Rolls-Royce and Snecma for

1495-560: The Mikoyan-Gurevich I-310 , on January 8, 1948. The first prototype was however lost on May 11, 1948 due to vibrations. Trials were continued with an improved second prototype, designated Aircraft 174D , which underwent State Acceptance Tests from August to September 25, 1948. In comparison with the Nene-powered MiG-15 it had almost the same maximum speed and better maneuverability, with somewhat reduced rate of climb. The type

1560-515: The North American XB-70 Valkyrie , each feeding three engines with an intake airflow of about 800 pounds per second (360 kg/s). The turbine rotates the compressor at high speed, adding energy to the airflow while squeezing (compressing) it into a smaller space. Compressing the air increases its pressure and temperature. The smaller the compressor, the faster it turns. The (large) GE90-115B fan rotates at about 2,500 RPM, while

1625-479: The Rolls-Royce Welland and Rolls-Royce Derwent , and by 1949 the de Havilland Goblin , being type tested for 500 hours without maintenance. It was not until the 1950s that superalloy technology allowed other countries to produce economically practical engines. Early German turbojets had severe limitations on the amount of running they could do due to the lack of suitable high temperature materials for

1690-424: The Tu-144 , also used afterburners as does Scaled Composites White Knight , a carrier aircraft for the experimental SpaceShipOne suborbital spacecraft. Reheat was flight-trialled in 1944 on the W.2/700 engines in a Gloster Meteor I . The net thrust F N {\displaystyle F_{N}\;} of a turbojet is given by: F N = ( m ˙

1755-542: The 150F the second-fastest Soviet fighter of the period, after the MiG-9 powered by two afterburning RD-21 engines. Nevertheless, Lavochkin decided not to submit the 150F for state acceptance trials as the fundamental design flaws of the airframe still had not been resolved. Data from Early Soviet Jet Fighters General characteristics Performance Armament Aircraft of comparable role, configuration, and era Related lists Turbojet The turbojet

1820-817: The MiG-15bis. The remaining La-15s in service were disarmed by 1953, and their engines reused on the KS-1 Komet air-to-surface missile. The aircraft were expended as targets at various nuclear bomb tests. An La-15 is on display at the Central Air Force Museum at Monino , outside of Moscow, Russia. Data from Lavochkins Last Jets General characteristics Performance Armament Related development Aircraft of comparable role, configuration, and era Related lists Lavochkin La-150 The Lavochkin La-150 (also known as

1885-620: The Soviets in 1947 and then copied as the Klimov RD-500 and Klimov RD-45 respectively. The Derwent-powered Aircraft 174 was designed as a backup for the main program, the Nene-powered Aircraft 168, in case the British failed to deliver more powerful Nene engines with afterburners (which they did fail to deliver). The first prototype of Aircraft 174 was flown just 9 days after its counterpart

1950-464: The aircraft decreases the efficiency of the engine because it has been compressed, but then does not contribute to producing thrust. Compressor types used in turbojets were typically axial or centrifugal. Early turbojet compressors had low pressure ratios up to about 5:1. Aerodynamic improvements including splitting the compressor into two separately rotating parts, incorporating variable blade angles for entry guide vanes and stators, and bleeding air from

2015-403: The aircraft from Gorky to Moscow and their wings could not be dismounted which meant that they could not be railed to Moscow either. Special three-wheeled trailers were built and the aircraft were driven to Moscow, but the flypast was cancelled because of bad weather. The tests conducted in preparation for the parade revealed a number of flaws in the design including poor directional stability,

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2080-404: The bottom of the rear fuselage from the engine's exhaust. Air was supplied by an intake in the aircraft nose that split around the cockpit before reaching the engine. Seven tanks, five in the fuselage and one in each wing, carried a total of 500 kilograms (1,100 lb) of fuel. Construction of a full-scale mockup was completed in June 1945 by Factory No. 81, but the order for five prototypes

2145-410: The combustion chamber. Fuel is mixed with the compressed air and burns in the combustor. The combustion products leave the combustor and expand through the turbine where power is extracted to drive the compressor. The turbine exit gases still contain considerable energy that is converted in the propelling nozzle to a high speed jet. The first turbojets, used either a centrifugal compressor (as in

2210-432: The combustor and pass through to the turbine in a continuous flowing process with no pressure build-up. Instead, a small pressure loss occurs in the combustor. The fuel-air mixture can only burn in slow-moving air, so an area of reverse flow is maintained by the fuel nozzles for the approximately stoichiometric burning in the primary zone. Further compressed air is introduced which completes the combustion process and reduces

2275-421: The compressor enabled later turbojets to have overall pressure ratios of 15:1 or more. After leaving the compressor, the air enters the combustion chamber. The burning process in the combustor is significantly different from that in a piston engine . In a piston engine, the burning gases are confined to a small volume, and as the fuel burns, the pressure increases. In a turbojet, the air and fuel mixture burn in

2340-401: The compressor is passed through these to keep the metal temperature within limits. The remaining stages do not need cooling. In the first stage, the turbine is largely an impulse turbine (similar to a pelton wheel ) and rotates because of the impact of the hot gas stream. Later stages are convergent ducts that accelerate the gas. Energy is transferred into the shaft through momentum exchange in

2405-521: The compressor stage. Well-known examples are the Concorde and Lockheed SR-71 Blackbird propulsion systems where the intake and engine contributions to the total compression were 63%/8% at Mach 2 and 54%/17% at Mach 3+. Intakes have ranged from "zero-length" on the Pratt & Whitney TF33 turbofan installation in the Lockheed C-141 Starlifter , to the twin 65 feet (20 m) long, intakes on

2470-475: The high-temperature materials used in their turbosuperchargers during World War II. Water injection was a common method used to increase thrust, usually during takeoff, in early turbojets that were thrust-limited by their allowable turbine entry temperature. The water increased thrust at the temperature limit, but prevented complete combustion, often leaving a very visible smoke trail. Allowable turbine entry temperatures have increased steadily over time both with

2535-441: The introduction of superior alloys and coatings, and with the introduction and progressive effectiveness of blade cooling designs. On early engines, the turbine temperature limit had to be monitored, and avoided, by the pilot, typically during starting and at maximum thrust settings. Automatic temperature limiting was introduced to reduce pilot workload and reduce the likelihood of turbine damage due to over-temperature. A nose bullet

2600-401: The jet V j {\displaystyle V_{j}\;} must exceed the true airspeed of the aircraft V {\displaystyle V\;} if there is to be a net forward thrust on the airframe. The speed V j {\displaystyle V_{j}\;} can be calculated thermodynamically based on adiabatic expansion . The operation of a turbojet

2665-402: The opposite way to energy transfer in the compressor. The power developed by the turbine drives the compressor and accessories, like fuel, oil, and hydraulic pumps that are driven by the accessory gearbox. After the turbine, the gases expand through the exhaust nozzle producing a high velocity jet. In a convergent nozzle, the ducting narrows progressively to a throat. The nozzle pressure ratio on

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2730-480: The original engine. Its power, however, was increased by an additional 340 kilograms-force (3.3 kN; 750 lbf), over 30% more thrust. This engine was designated the izdeliye YuF by the bureau and was fitted into an aircraft 150 prototype in July 1947, designated as the 150F. The additional power increased the aircraft's top speed to 950 km/h (590 mph) at sea level and 915 km/h (569 mph) at an altitude of 4,320 meters (14,170 ft). This made

2795-413: The program with three more aircraft built in record time with support from Factory No. 301. Tooling was constructed in 5–10 days with the first aircraft completed in a week and a half. All eight aircraft were complete by 1 November and had been tested to ensure their readiness to participate in the parade. They were later given the unofficial service designation of La-13. It was considered too risky to fly

2860-411: The rear fuselage, wings and tail needed to be reinforced, and the opportunity was taken to enlarge the vertical stabilizer as well. These tests and modifications required six months of work so that the first flying prototype was not completed until July 1946. Manufacturer's testing of the first prototype began on 27 August, after ground testing had required replacing the engine twice, and the first flight

2925-519: The same year. One unit was seemingly the 196th Fighter Aviation Regiment. Introduction was accompanied by numerous accidents, but the competing MiG-15 design fared little better. However, although the La-15 had a number of technical advantages over the MiG-15, a combination of easier manufacture and lower costs led to the MiG-15 being favoured. The Soviet authorities decided to produce only one fighter, and they chose

2990-468: The supersonic airliner, in terms of miles per gallon, compared to subsonic airliners at Mach 0.85 (Boeing 707, DC-8) was relatively small. This is because the large increase in drag is largely compensated by an increase in powerplant efficiency (the engine efficiency is increased by the ram pressure rise which adds to the compressor pressure rise, the higher aircraft speed approaches the exhaust jet speed increasing propulsive efficiency). Turbojet engines had

3055-446: The temperature of the combustion products to a level which the turbine can accept. Less than 25% of the air is typically used for combustion, as an overall lean mixture is required to keep within the turbine temperature limits. Hot gases leaving the combustor expand through the turbine. Typical materials for turbines include inconel and Nimonic . The hottest turbine vanes and blades in an engine have internal cooling passages. Air from

3120-437: The tests as the first prototype alone required four engine changes. After the conclusion of the manufacturer's trials in April 1947, one aircraft was returned to the factory for extensive modifications as the 150M. The wing tips were angled downward 35° to reduce the lateral stability, the wing was redesigned to detach from the fuselage, and the aerodynamic balancing of the elevators was reduced from 24% to 20%. The fuel capacity

3185-535: The thrust from a turbojet engine. It was flown by test pilot Erich Warsitz . The Gloster E.28/39 , (also referred to as the "Gloster Whittle", "Gloster Pioneer", or "Gloster G.40") made the first British jet-engined flight in 1941. It was designed to test the Whittle jet engine in flight, and led to the development of the Gloster Meteor. The first two operational turbojet aircraft, the Messerschmitt Me 262 and then

3250-563: The time that they were completed. Even one variant with a much more powerful engine was inferior to other aircraft that the OKB had under development and all work was terminated in 1947. The Lavochkin OKB was ordered to design a fighter using a single Junkers Jumo 004 B axial-flow turbojet in February 1945. Much like their rivals at the Mikoyan-Gurevich OKB with their MiG-9 , the OKB chose

3315-708: The turbine. The turbine exhaust is then expanded in the propelling nozzle where it is accelerated to high speed to provide thrust. Two engineers, Frank Whittle in the United Kingdom and Hans von Ohain in Germany , developed the concept independently into practical engines during the late 1930s. Turbojets have poor efficiency at low vehicle speeds, which limits their usefulness in vehicles other than aircraft. Turbojet engines have been used in isolated cases to power vehicles other than aircraft, typically for attempts on land speed records . Where vehicles are "turbine-powered", this

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3380-412: The turbines would overheat, the lubricating oil would leak from the bearing cavities, the rotor thrust bearings would skid or be overloaded, and ice would form on the nose cone. The air from the compressor, called secondary air, is used for turbine cooling, bearing cavity sealing, anti-icing, and ensuring that the rotor axial load on its thrust bearing will not wear it out prematurely. Supplying bleed air to

3445-464: The turbines. British engines such as the Rolls-Royce Welland used better materials giving improved durability. The Welland was type-certified for 80 hours initially, later extended to 150 hours between overhauls, as a result of an extended 500-hour run being achieved in tests. General Electric in the United States was in a good position to enter the jet engine business due to its experience with

3510-578: The unmodified aircraft. Given that a higher-performance design, the Aircraft 156 , had already been submitted for state acceptance trials, Semyon Lavochkin decided not to continue the development of the 150M. In the meantime, the OKB had been developing two afterburning versions of the RD-10 in an effort to increase the engine's power. The more successful model was only 100 millimeters (3.9 in) longer and weighed an additional 31 kilograms (68 lb) more than

3575-484: Was also armored. Two 23-millimetre (0.91 in) Nudelman-Suranov NS-23 autocannon were mounted on the lower side of the fuselage with 75 rounds per gun. The tricycle landing gear retracted into the fuselage which gave the 150 a very narrow track. The Soviet derivative of the Jumo engine, the RD-10, was rated at 900 kilograms-force (8.8 kN; 2,000 lbf) and was mounted behind the cockpit. A steel heat shield protected

3640-481: Was an advantage at high altitude. Nevertheless, official enthusiasm for the La-15 was mild, largely because it was a complex design that required complicated and expensive production tooling. Only 235 La-15s were built, serving with the Soviet Air Force until 1953. The La-15 was tested operationally by the 192nd Fighter Wing, based at Kubinka from 19 March 1949, and began appearing in front-line combat units later

3705-694: Was designed to use the new turbojet based on the Rolls-Royce Nene in response to a 1946 request for an advanced swept-wing jet fighter capable of transonic performance. The engine was placed behind the pilot, but with a high-mounted wing and T-tail compared to the similar MiG-15 . The La-15 which reached mass production was the outcome of a series of development aircraft that began with the Aircraft 150 bomber in 1945 and culminated in Aircraft 176, later in 1948. These aircraft were designed for British engines, Rolls-Royce Derwent V and Rolls-Royce Nene , acquired by

3770-428: Was given to Factory No. 381 as Factory No. 81 was already fully committed to other programs. Manufacturing drawings were delivered to Factory No. 381 by the end of August, but the prototypes were delayed because the plant had no experience building metal aircraft and lacked the necessary tooling. By the end of the year, the factory had only managed to complete a single airframe for static load testing. This showed that

3835-501: Was increased to 660 kilograms (1,460 lb), the cockpit was widened by 80 centimeters (31 in) and fitted with an ejection seat . Fore and aft armor plates were fitted to protect the pilot and a new radio aerial mast was installed. All these changes added 365 kilograms (805 lb) of weight and increased drag which reduced the aircraft's top speed by 73 to 805 km/h (45 to 500 mph), and slowed its time to 5,000 meters (16,400 ft) from 4.8 to 7.2 minutes in comparison to

3900-424: Was liquid-fuelled. Whittle's team experienced near-panic during the first start attempts when the engine accelerated out of control to a relatively high speed despite the fuel supply being cut off. It was subsequently found that fuel had leaked into the combustion chamber during pre-start motoring checks and accumulated in pools, so the engine would not stop accelerating until all the leaked fuel had burned off. Whittle

3965-659: Was made on 11 September. The following day, the Council of Ministers ordered that a small batch of jets from each OKB were to participate in the 7 November parade commemorating the October Revolution . Because of the tight deadline, the components for the two incomplete prototypes were turned over to Factory No. 301 at Khimki , the new headquarters for the Lavochkin OKB, for assembly by Factory No. 381. Factory No. 21 in Gorky joined

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4030-531: Was not yet ready for production. The design was completed quickly, but the construction of the five flying prototypes was protracted by the factory's inexperience in building metal aircraft. The aircraft made its first flight in September 1946, but proved to require extensive modifications to meet the Soviet Air Forces ' requirements. These took so long to make and test that the aircraft was essentially obsolete by

4095-412: Was ordered into production in September 1948, even while Aircraft 174D was undergoing flight trials, and given the official designation La-15 in April 1949. The La-15 had a barrel-like fuselage, shoulder-mounted swept wings with 6 degrees anhedral, and stabilizers mounted high on the fin, almost a T-tail. It was popular with pilots because of its easy handling and reliability, and its pressurized cockpit

4160-629: Was tested on the Power Jets W.1 in 1941 initially using ammonia before changing to water and then water-methanol. A system to trial the technique in the Gloster E.28/39 was devised but never fitted. An afterburner or "reheat jetpipe" is a combustion chamber added to reheat the turbine exhaust gases. The fuel consumption is very high, typically four times that of the main engine. Afterburners are used almost exclusively on supersonic aircraft , most being military aircraft. Two supersonic airliners, Concorde and

4225-479: Was unable to interest the government in his invention, and development continued at a slow pace. In Germany, Hans von Ohain patented a similar engine in 1935. His design, an axial-flow engine, as opposed to Whittle's centrifugal flow engine, was eventually adopted by most manufacturers by the 1950s. On 27 August 1939 the Heinkel He 178 , powered by von Ohain's design, became the world's first aircraft to fly using

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