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75-508: Boeing adapted many systems used in jet airplanes for hydrofoils. Robert Bateman led development. Boeing launched its first passenger-carrying waterjet-propelled hydrofoil in April 1974. It could carry from 167 to 400 passengers. It was based on technology developed for the U.S. Navy patrol hydrofoil Tucumcari , and shared technology with the Pegasus -class military patrol hydrofoils . The product line

150-416: 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

225-580: 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

300-510: A highly flammable fabric surface. During the 1920s and 1930s a number of approaches were tried. A variety of motorjet , turboprop , pulsejet and rocket powered aircraft were designed. Rocket-engine research was being carried out in Germany and the first aircraft to fly under rocket power was the Lippisch Ente , in 1928. The Ente had previously been flown as a glider. The next year, in 1929,

375-553: A jet fighter on 26 July 1944, the day before the British Gloster Meteor entered operational service. The Me 262 had first flown on April 18, 1941, but mass production did not start until early 1944, with the first squadrons operational that year, too late for any effect on the outcome of the World War II . While only around 15 Meteors were operational during WW2, up to 1,400 Me 262 were produced, with 300 entering combat. Only

450-516: A jet-powered aircraft in 1910, the Coandă-1910 . However, to support this claim, he had to make substantial alterations to the drawings which he used to support his subsequently debunked claims. In fact the ducted-fan engine backfired, setting the aircraft on fire before any flights were ever made, and it lacked nearly all of the features necessary for a jet engine - including a lack of fuel injection, and any concern about hot jet efflux being directed at

525-542: 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

600-509: A lower exhaust speed than turbojets, and are mostly used for high sonic, transonic, and low supersonic speeds. High bypass turbofans are relatively efficient, and are used by subsonic aircraft such as airliners. Jet aircraft fly considerably differently than propeller aircraft . One difference is that jet engines respond relatively slowly. This complicates takeoff and landing maneuvers. In particular, during takeoff, propeller aircraft engines blow air over their wings and that gives more lift and

675-454: 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

750-413: A shorter takeoff. These differences caught out some early BOAC Comet pilots. In aircraft overall propulsive efficiency η {\displaystyle \eta } is the efficiency, in percent, with which the energy contained in a vehicle's propellant is converted into useful energy, to replace losses due to air drag , gravity, and acceleration. It can also be stated as the proportion of

825-411: 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

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900-405: 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,

975-422: A speed that is the same as, or nearly the same as, the vehicle velocity. The exact formula for air-breathing engines as given in the literature, is where c is the exhaust speed, and v is the speed of the aircraft. For a long range jet operating in the stratosphere , the speed of sound is constant, hence flying at fixed angle of attack and constant Mach number causes the aircraft to climb, without changing

1050-513: 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

1125-512: 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

1200-494: 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

1275-480: 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

1350-495: A version of the Whittle engine built by General Electric . The Meteor was the first production jet, with the first orders for production examples being made on 8 August 1941, the prototype first flying on 5 March 1943 and the first production aircraft flying on 12 January 1944, while the first orders for production Me 262 aircraft were not issued until 25 May 1943, and the first production Me 262 did not fly until 28 March 1944 despite

1425-413: 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

1500-523: 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

1575-533: Is known as the Breguet range equation after the French aviation pioneer Louis Charles Breguet . Turbojet The turbojet 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

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1650-568: 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

1725-585: 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

1800-650: Is the X-15 at Mach 6.85. The Space Shuttle , while far faster than the X-43 or X-15, was not regarded as an aircraft during ascent as it was carried ballistically by rocket thrust, rather than the air. During re-entry it was classed (like a glider) as an unpowered aircraft. The first flight was in 1981. The Bell 533 (1964), Lockheed XH-51 (1965), and Sikorsky S-69 (1977-1981) are examples of compound helicopter designs where jet exhaust added to forward thrust. The Hiller YH-32 Hornet and Fairey Ultra-light Helicopter were among

1875-427: Is the cycle efficiency and η p {\displaystyle \eta _{p}} is the propulsive efficiency. The cycle efficiency, in percent, is the proportion of energy that can be derived from the energy source that is converted to mechanical energy by the engine . For jet aircraft the propulsive efficiency (essentially energy efficiency ) is highest when the engine emits an exhaust jet at

1950-565: Is therefore an important consideration. Jet aircraft are usually designed using the Whitcomb area rule , which says that the total area of cross-section of the aircraft at any point along the aircraft from the nose must be approximately the same as that of a Sears-Haack body . A shape with that property minimises the production of shockwaves which would waste energy. There are several types of engine which operate by expelling hot gas: The different types are used for different purposes. Rockets are

2025-647: The Boeing 707 to enter service in 1958 and thus to dominate the market for civilian airliners. The underslung engines were found to be advantageous in the event of a propellant leak, and so the 707 looked rather different from the Comet: the 707 has a shape that is effectively the same as that of contemporary aircraft, with marked commonality still evident today for example with the 737 (fuselage) and A340 (single deck, swept wing, four below-wing engines). Turbofan aircraft with far greater fuel efficiency began entering service in

2100-671: The English Channel , the Canary Islands , the Korea Strait , Saudi Arabia , and Indonesia . In 1979, the Royal Navy purchased a Boeing Jetfoil, HMS Speedy , to provide the Royal Navy with an opportunity to gain practical experience in the operation and support of a modern hydrofoil, to establish technical and performance characteristics, and to assess the capability of a hydrofoil in

2175-613: 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

2250-760: The Fishery Protection Squadron . In 1980, B&I shipping lines opened a Jetfoil service from Dublin to Liverpool with the Jetfoil Cú Na Mara (English: Hound of the Sea ). The service was not a success and was discontinued at the end of the 1981 season. The Belgian Regie voor Maritiem Transport (RMT) operated the Jetfoils Princesse Clementine and Prinses Stephanie on the Ostend – Dover route from 1981 until 1997. In North America ,

2325-631: 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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2400-571: 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

2475-721: The Nakajima J9Y Kikka , a modified, and slightly smaller version of the Me 262 that had folding wings. By the end of 1945, the US had introduced their first jet fighter, the Lockheed P-80 Shooting Star into service and the UK its second fighter design, the de Havilland Vampire . The US introduced the North American B-45 Tornado , their first jet bomber, into service in 1948. It was capable of carrying nuclear weapons, but

2550-515: 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

2625-554: The Opel RAK.1 became the first purpose-built rocket aircraft to fly. The turbojet was invented in the 1930s, independently by Frank Whittle and later Hans von Ohain . The first turbojet aircraft to fly was the Heinkel He 178 , on August 27, 1939 in Rostock (Germany), powered by von Ohain's design. This was largely a proof of concept, as the problem of " creep " (metal fatigue caused by

2700-479: 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

2775-424: 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 ˙

2850-488: The speed of sound . Jet aircraft generally cruise most efficiently at about Mach 0.8 (981 km/h (610 mph)) and at altitudes around 10,000–15,000 m (33,000–49,000 ft) or more. The idea of the jet engine was not new, but the technical problems involved did not begin to be solved until the 1930s. Frank Whittle , an English inventor and RAF officer, began development of a viable jet engine in 1928, and Hans von Ohain in Germany began work independently in

2925-541: The 1950s and 1960s, and became the most commonly used type of jet. The Tu-144 supersonic transport was the fastest commercial jet aircraft at Mach 2.35 (2,503 km/h (1,555 mph)). It went into service in 1975, but was withdrawn from commercial service shortly afterwards. The Mach 2 Concorde entered service in 1976 and flew for 27 years. The fastest military jet aircraft was the SR-71 Blackbird at Mach 3.35 (3,661 km/h (2,275 mph)). Most people use

3000-610: The Boeing Jetfoil saw regularly scheduled service between Seattle, Washington and Victoria, British Columbia during the summer tourist season of 1980. Leased from Boeing, a single Jetfoil, the Flying Princess , was operated by the non-profit Flying Princess Transportation Corp., with the close co-operation and assistance of the B.C. Steamship Company. Regularly scheduled service ran from Seattle to Victoria to Vancouver from April to September 1985 by Island Jetfoil. Boeing reclaimed

3075-712: The Island Jetfoil boat and sold it for service in Japan. Built under license by Kawasaki Heavy Industries Ltd. in Kobe, Japan Built under license by Shanghai Simno Marine Ltd. CSSC, China Jet airplanes A jet aircraft (or simply jet ) is an aircraft (nearly always a fixed-wing aircraft ) propelled by one or more jet engines . Whereas the engines in propeller-powered aircraft generally achieve their maximum efficiency at much lower speeds and altitudes, jet engines achieve maximum efficiency at speeds close to or even well above

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3150-472: The Me 262 program having started earlier than that of the Meteor, as Projekt 1065, with initial plans drawn up by Waldemar Voigt's design team in April 1939. The Messerschmitt Me 262 was the first operational jet fighter , manufactured by Germany during World War II and entering service on 19 April 1944 with Erprobungskommando 262 at Lechfeld just south of Augsburg. An Me 262 scored the first combat victory for

3225-464: 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

3300-410: 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

3375-432: 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

3450-421: 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

3525-810: The compressor is heated by burning fuel in the combustion chamber and then allowed to expand through 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

3600-401: 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

3675-521: 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

3750-492: The early 1930s. In August 1939 the turbojet powered Heinkel He 178 , the world's first jet aircraft, made its first flight. A wide range of different types of jet aircraft exist, both for civilian and military purposes. After the first instance of powered flight, a large number of jet engine designs were suggested. René Lorin , Morize, Harris proposed systems for creating a jet efflux. After other jet engines had been run, Romanian inventor Henri Coandă claimed to have built

3825-458: The first commercial jet service, from London to Johannesburg , in 1952 with the de Havilland Comet jetliner . This highly innovative aircraft travelled far faster and higher than propeller aircraft, was much quieter, smoother, and had stylish blended wings containing hidden jet engines. However, due to a design defect, and use of aluminium alloys, the aircraft suffered catastrophic metal fatigue which led to several crashes, which gave time for

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3900-485: The high temperatures within the engine) had not been solved, and the engine quickly burned out. Von Ohain's design, an axial-flow engine, as opposed to Whittle's centrifugal flow engine, was eventually adopted by most manufacturers by the 1950s. The first flight of a jet-propelled aircraft to come to public attention was the Italian Caproni Campini N.1 motorjet prototype which flew on August 27, 1940. It

3975-475: 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

4050-441: 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

4125-401: 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

4200-476: The many helicopters where the rotors were driven by tip jets . Jet-powered wingsuits exist – powered by model aircraft jet engines – but of short duration and needing to be launched at height. Because of the way they work, the typical exhaust speed of jet engines is transonic or faster, therefore most jet aircraft need to fly at high speeds, either supersonic or speeds just below the speed of sound (" transonic ") so as to achieve efficient flight. Aerodynamics

4275-576: The mechanical energy actually used to propel the aircraft. It is always less than 100% because of kinetic energy loss to the exhaust, and less-than-ideal efficiency of the propulsive mechanism, whether a propeller , a jet exhaust, or a fan. In addition, propulsive efficiency is greatly dependent on air density and airspeed. Mathematically, it is represented as η = η c η p {\displaystyle \eta =\eta _{c}\eta _{p}} where η c {\displaystyle \eta _{c}}

4350-399: The oldest type, and are mainly used when extremely high speeds are needed, or operation at extremely high altitudes where there is insufficient air to operate a jet engine. Due to the extreme, typically hypersonic , exhaust velocity and the necessity of oxidiser being carried on board, they consume propellant extremely quickly, making them impractical for routine transportation. Turbojets are

4425-402: 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

4500-549: The rocket-propelled Messerschmitt Me 163 Komet was a faster operational aircraft during the war. Around this time, mid 1944, the United Kingdom's Meteor was being used for defence of the UK against the V-1 flying bomb  – the V-1 itself a pulsejet -powered aircraft and direct ancestor of the cruise missile  – and then ground-attack operations over Europe in the last months of

4575-409: The second oldest type; they have a high, usually supersonic, exhaust speed and low frontal cross-section, and so are best suited to high-speed, usually supersonic, flight. Although once widely used, they are relatively inefficient compared to turboprop and turbofans for subsonic flight. The last major aircraft to use turbojets were Concorde and Tu-144 supersonic transports . Low bypass turbofans have

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4650-468: 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

4725-446: 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

4800-484: The term 'jet aircraft' to denote gas turbine based airbreathing jet engines , but rockets and scramjets are both also propelled by jet propulsion. Cruise missiles are single-use unmanned jet aircraft, powered predominantly by ramjets or turbojets or sometimes turbofans, but they will often have a rocket propulsion system for initial propulsion. The fastest airbreathing jet aircraft is the unmanned X-43 scramjet at around Mach 9–10. The fastest manned (rocket) aircraft

4875-485: 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

4950-412: 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

5025-464: 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

5100-578: The value of the local speed of sound. In this case: V = a M {\displaystyle V=aM} where M {\displaystyle M} is the cruise Mach number and a {\displaystyle a} the local speed of sound. The range equation can be shown to be: R = a M c T C L C D l n W 1 W 2 {\displaystyle R={\frac {aM}{c_{T}}}{\frac {C_{L}}{C_{D}}}ln{\frac {W_{1}}{W_{2}}}} which

5175-481: The war. In 1944 Germany introduced the Arado Ar 234 jet reconnaissance and bomber aircraft into service, though chiefly used in the former role, with the Heinkel He 162 Spatz single-jet light fighter appearing at the end of 1944. USSR tested its own Bereznyak-Isayev BI-1 in 1942, but the project was scrapped by leader Joseph Stalin in 1945. The Imperial Japanese Navy also developed jet aircraft in 1945, including

5250-755: Was licensed to the Japanese company Kawasaki Heavy Industries . Boeing launched three Jetfoil 929-100 hydrofoils that were acquired in 1975 for service in the Hawaiian Islands , which were operated by Honolulu -based operator Seaflite. Seaflite operated three Boeing 929-100 Jetfoils between 1975 and the company's demise in 1979. When the service ended, the three hydrofoils were acquired by Shun Tak Holdings ' Far East Hydrofoil (now TurboJET ) for service between Hong Kong and Macau . About two dozen Boeing Jetfoils saw service in Hong Kong–Macau, Japan , South Korea ,

5325-424: 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

5400-629: 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

5475-697: Was the first jet aircraft recognised by the Fédération Aéronautique Internationale (at the time the German He 178 program was still kept secret). Campini began development of the motorjet in 1932; it differed from a true turbojet in that the turbine was driven by a piston engine, rather than combustion of the turbine gases - which was a much more complex solution. The British experimental Gloster E.28/39 first flew on May 15, 1941, powered by Sir Frank Whittle 's turbojet. The United States Bell XP-59A flew on October 1, 1942, using two examples of

5550-427: 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

5625-622: Was used for reconnaissance over Korea. On November 8, 1950, during the Korean War , United States Air Force Lt. Russell J. Brown, flying in an F-80 , intercepted two North Korean MiG-15s near the Yalu River and shot them down in the first jet-to-jet dogfight in history. The UK put the English Electric Canberra into service in 1951 as a light bomber . It was designed to fly higher and faster than any interceptor . BOAC operated

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