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87-474: The Tumansky R-21 was a Soviet turbojet engine of the 1960s. Used for development only, the project was canceled. The Tumansky R-21 was developed at Tushino motor plant (part of OKB-300), headed by Nikolai Georgievich Metskhvarishvili , as a twin-spool axial-flow afterburning turbojet. It was based on the Tumansky R-11 with the goal of increasing thrust and airflow, using a new six-stage compressor with

174-416: 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

261-811: A Ye-8, exploded in mid-air after compressor failure; test pilot Georgy Mosolov survived the ejection at Mach 1.78, but he never fully recovered. Shortly afterward the Ye-8 program was cancelled along with R-21 development in favour of heavier fighter planes such as the Mikoyan-Gurevich MiG-23 , which required more powerful engines. Related development Related lists Turbojet 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

348-477: A centrifugal compressor with a radial inflow turbine, a design that proved to be impractical and as a result, despite much effort, was never put into production. By comparison, Whittle's centrifugal flow engines, in both straight-through and reverse flow configuration (developed further by Rolls Royce), powered all Allied World War II jets and the majority of immediate post-war fighters. They were built under licence in numerous countries including Australia, France and

435-455: A combustion chamber of unknown endurance to flight readiness, I came upon the idea of separating the turbine problem from the combustion chamber problem by using hydrogen fuel. As a physicist, I knew of course that the diffusion and combustion speed of gaseous hydrogen was substantially greater than that of petrol." A study of the model's airflow resulted in several improvements over a two-month period. Encouraged by these findings, Ohain produced

522-639: A fuel system to enable it to run self-contained on liquid fuel, which was achieved in September 1937. With the heavy backing of Heinkel, Ohain's jet engine was the first to power an aircraft, the Heinkel He 178 aircraft in 1939, which was followed by Whittle's engine within the Gloster E.28/39 in 1941. Turbojet powered fighter aircraft from both Germany and Britain entered operational use virtually simultaneously in July 1944:

609-580: 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

696-542: 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

783-595: A larger diameter and different rotor blades than its predecessor as well as a new afterburner chamber and variable exhaust nozzle. The increased pressure ratio and turbine inlet temperature required components to be fabricated from advanced alloys. Several contemporary Soviet aircraft were planned to use the R-21, including the Sukhoi T-58 , Sukhoi T-6 and the Mikoyan-Gurevich Ye-8 . On September 11, 1962 an R-21, fitted to

870-444: A local garage, Bartles and Becker. There he met an automotive mechanic, Max Hahn, and eventually arranged for him to build a demonstration model of his engine for 500  ℛ︁ℳ︁ . The completed model was larger in diameter than Whittle's fully working engine of 1937, although much shorter. Ohain took the model to the university for testing but ran into problems with combustion of the petrol fuel, which took place mostly after

957-662: A meeting between his engineers and Ohain, during which he argued that the current "garage engine" would never work, but that the concept upon which it was based was sound. The engineers were convinced, and in April Ohain and Hahn began working for Heinkel at the Marienehe airfield outside Rostock , in Warnemuende. Working with Engineer Gundermann and Hahn in Special Development, von Ohain states: "Under pressure of aiming to bring

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1044-549: A new "pet project" of his own, eventually becoming the Heinkel HeS 011 . Although this was the first of Schelp's "Class II" engines to start working well, production had still not started when the war ended. Work continued on the HeS 8 for some time, but it was eventually abandoned in the spring of 1943. Part of the challenge for von Ohain was his approach to designing a practical turbojet that could be developed. His primary design comprised

1131-466: A new prototype that would run on hydrogen gas supplied by an external pressurised source. The resulting Heinkel-Strahltriebwerk 1 (HeS 1), German for Heinkel Jet Engine 1, was built by hand-picking some of the best machinists in the company, much to the chagrin of the shop-floor supervisors. Hahn, meanwhile, worked on the combustion problem, an area in which he had some experience. The engine was extremely simple, made largely of sheet metal. Construction, by

1218-492: A patent of an idea ... We thought that it was not seriously being worked on." In February 1937, the turbine section was running on a test stand. According to von Ohain, "We were now working on a machine capable of powering an aircraft, the forerunner of the He-S3B. I had intended to put the combustion chamber between the compressor and the turbine, as we had done with the hydrogen unit, but Hahn suggested putting it ahead of them, which

1305-440: A patent on his version of a jet engine, Process and Apparatus for Producing Airstreams for Propelling Airplanes . Unlike Frank Whittle 's Power Jets WU design with its axial flow turbine, Ohain used a radial in-flow turbine to go with a centrifugal compressor , placing them back-to-back with an annular combustion space wrapped around the rotor. While working at the university, Ohain used to take his sports car to be serviced at

1392-583: A radial inflow turbine. Ultimately, this configuration had too many shortcomings to be put into production; however, aided by the enormous resources of the Heinkel Aircraft Company, a developed version was sufficient to power the He-178, and on 27 August 1939 von Ohain entered history as the designer of the world's first gas turbine to power an aircraft. Von Ohain stayed with centrifugal designs, contributing his research to Heinkel's other projects such as

1479-454: 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

1566-512: A second one was nearing completion at about the same time as a new test airframe, the Heinkel He 178 , which first flew on 27 August 1939, the first jet-powered aircraft to fly by test pilot Erich Warsitz . Heinkel had applied, May 31, 1939, for a patent: US2256198 Espacenet - Original document , an 'Aircraft power plant', inventor Max Hahn. First application for this patent in Germany was May, 1938. Work started immediately on larger versions, first

1653-411: 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

1740-405: 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,

1827-513: 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

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1914-512: 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

2001-494: 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

2088-483: A two-flow, dual entrance flow radial flow compressor that looked monstrous from an engine point of view. Its flow reversal looked to us to be an undesirable thing, but it turned out that it wasn't so bad after although it gave some minor instability problems ... Our patent claims had to be narrowed in comparison to Whittle's because Whittle showed certain things." He then somewhat understandably justified their knowledge of Whittle's work by saying: "We felt that it looked like

2175-480: 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

2262-531: Is a call for the newer models being developed to advance its control systems to implement the newest knowledge from the areas of automation, so increase its safety and effectiveness. Hans von Ohain Hans Joachim Pabst von Ohain (14 December 1911 – 13 March 1998) was a German physicist, engineer, and the designer of the first aircraft to use a turbojet engine. Together with Frank Whittle and Anselm Franz , he has been described as

2349-413: 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

2436-523: 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

2523-568: 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

2610-585: 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

2697-568: The BMW 003 . By early 1942 the HeS 8, officially the 109-001 (HeS 001), was still not progressing well. Meanwhile, Müller's HeS 30, officially the 109-006 (HeS 006), was developing much more quickly. Both engines were still some time from being ready for production, however, while the 003 and 004 appeared to be ready to go. In early 1942 the director of jet development at the RLM, Helmut Schelp , refused further funding for both designs, and ordered Heinkel to work on

Tumansky R-21 - Misplaced Pages Continue

2784-606: The Charles Stark Draper Prize for their work on turbojet engines. Ohain was elected a member of the U.S. National Academy of Engineering (NAE). Ohain was awarded the Ludwig-Prandtl-Ring from the Deutsche Gesellschaft für Luft- und Raumfahrt (German Society for Aeronautics and Astronautics) for "outstanding contribution in the field of aerospace engineering" in 1992. In 1982, Ohain was inducted into

2871-613: 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

2958-632: 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

3045-518: 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

3132-714: The International Air & Space Hall of Fame at the San Diego Air & Space Museum . In 1990, Ohain was inducted into the National Aviation Hall of Fame . Ohain died in Melbourne, Florida, in 1998, aged 86. He was survived by his wife and four children. One of his sons, Christopher von Ohain, joined the United States Marine Corps (USMC). Christopher’s son, Hans Christopher von Ohain, also joined

3219-501: The Me 262 on July 26 and the Gloster Meteor on July 27 of 1944. The Me 262 was the first operational fighter jet and saw flight combat with hundreds of machines, while the few dozen Meteors saw limited action. Although Von Ohain and Whittle both knew about axial flow compressors, they remained dedicated to improving centrifugal compressor engines to power respectively the Heinkel He 178 and

3306-515: 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

3393-479: 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

3480-424: 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 ˙

3567-897: The United States Air Force Exceptional Civilian Service Award, Systems Command Award for Exceptional Civilian Service, the Eugene M. Zuckert Management Award, the Air Force Special Achievement Award, and just before he retired, the Citation of Honor. In 1984–85, Ohain served as the Charles A. Lindbergh Chair in Aerospace History , a competitive senior fellowship at the National Air and Space Museum . In 1991 Ohain and Whittle were jointly awarded

Tumansky R-21 - Misplaced Pages Continue

3654-574: The Gloster E.28/39 until the end of the Second World War. Axial flow compressor jet engines were instead developed in parallel by Anselm Franz (Junkers) and Hermann Oestrich (BMW) to design the similar Jumo 004 and BMW 003 engines, designs that were eventually adopted by most manufacturers by the 1950s. After the war the two men met, became friends and received the Charles Stark Draper Prize for Engineering "for their independent development of

3741-452: The HeS 6 which was simply a larger HeS 3b, and then on a new design known as the HeS 8 which once again re-arranged the overall layout. The compressor and turbine were connected with a large-diameter drum long-enough to fit an annular combustion chamber between them. It was intended to install the engine on the Heinkel He 280 fighter , but the airframe development progressed much more smoothly than

3828-493: The RAF engineer ran the world's first jet engine on the 12th of April 1937), nevertheless Ohain had been given a copy of Whittle's patents by his lawyer, while his own patent application being prepared and before he had begun construction of an engine. In his biography, Ohain frankly critiqued Whittle's design: "When I saw Whittle's patent I was almost convinced that it had something to do with boundary layer suction combinations. It had

3915-707: The US and were copied by the Russians and Chinese to power the MiG-15 and MiG-17. Whittle's basic reverse flow design remains the most common gas turbine configuration in production today with over 80,000 built in the form of the Allison (RR) 250/300 and Pratt & Whitney PT6 series of engines. However, in his invention of HE S011 , von Ohain introduced a standard concept which combined axial and radial designs for most business jets today, along with turboprops and helicopters. In 1947, Ohain

4002-464: 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

4089-456: The airflow through the engine created a stable vortex that acted as the compressor and turbine. This interest in mass-flow led Ohain to research magnetohydrodynamics (MHD) for power generation, noting that the hot gases from a coal-fired plant could be used to extract power from their speed when exiting the combustion chamber, remaining hot enough to then power a conventional steam turbine. Thus an MHD generator could extract further power from

4176-500: The bent and folded sheet metal, and a re-arrangement of the layout to reduce the cross-sectional area of the engine by placing the annular combustor in an extended gap between the compressor and turbine. The original turbine was too small to work efficiently. In the beginning of 1939, the He-S3A was fitted into the He 178 airframe for a standing display at Roggentin on 3 July 1939. Yet this turbine

4263-473: The blacksmith in his village, started late in the summer of 1936 and was completed in March 1937. Two weeks later the engine was running on hydrogen, but the high temperature exhaust led to considerable "burning" of the metal. The tests were otherwise successful, and in September the combustor was replaced and the engine was run on gasoline for the first time. Running on gasoline caused the combustor to clog up. Although

4350-555: The co-inventor of the turbojet engine. However, the historical timelines show that von Ohain was still a university student when, in January 1930, Whittle filed his first patent for a turbojet engine and successfully tested his first engine in April 1937, some 6 months before von Ohain. Additionally, prior to designing his engine and filing his own patent in 1935, von Ohain had read and critiqued Whittle's patents. Von Ohain stated in his biography that "My interest in jet propulsion began in

4437-438: The coal, and lead to greater efficiencies. Unfortunately this design has proven difficult to build due to a lack of proper materials, namely high-temperature non-magnetic materials that are also able to withstand the chemically active exhaust. Ohain also investigated other power related concepts. He also invented the idea of the "jet wing", in which air from the compressor of a jet engine is bled off to large "augmented" vents in

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4524-607: The combined centrifugal/axial HeS8 and 011, but ultimately none of his designs was put into production. Other competing German designers at Junkers and BMW, following the axial design layout, saw their engines brought into production, although they never solved some of the basic power and durability problems. Von Ohain nevertheless started the world's first jet engine industry in his homeland of Germany, with many prototypes and series productions built until 1945 . Von Ohain, having entered turbojet design some time later than Whittle, began working on his first turbojet engine designs during

4611-410: 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

4698-432: 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

4785-421: 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

4872-401: 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

4959-521: 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

5046-643: The conclusion that a constant work process, i.e. constant compression, combustion, expansion, would have great advantages. Thus I chose a quite simple engine, a radial compressor with a radial turbine." However, the model he and Max Hahn built and tested in the courtyard of the Institute showed the combustion chamber needed further development. As a consequence, Pohl and von Ohain decided to approach Heinkel as someone who "doesn't back away from new ideas". In February 1936, Pohl wrote to Ernst Heinkel , telling him about Ohain's design and its possibilities. Heinkel arranged

5133-451: The early 1960s he did a fair amount of work on the design of gas core reactor rockets which would retain the nuclear fuel while allowing the working mass to be used as exhaust. The engineering needed for this role was also used for a variety of other "down to earth" purposes, including centrifuges and pumps. Ohain would later use the basic mass-flow techniques of these designs to create a fascinating jet engine with no moving parts, in which

5220-453: The engine was never intended to be a flight-quality design, it proved beyond a doubt that the basic concept was workable, and Ohain had at last caught up with Whittle. With vastly more funding and industry support, Ohain would soon overtake Whittle and forge ahead. It has often been claimed that Ohain was unaware of Whittle's work. While in a very strict sense this may be true (in that he was unaware of Whittle's experiments at Lutterworth where

5307-431: The engine, and had to be used in gliding tests while work on the engine continued. A flight-quality HeS 8 was installed in late March 1941, followed by the first flight on 2 April. Three days later the aircraft was demonstrated for a party of Nazi and RLM officials, all of whom were impressed. Full development funds soon followed. By this point there were a number of turbojet developments taking place in Germany. Heinkel

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5394-525: The entire tube. The final result of the changes was the He-S3B." A new design, the HeS 3b was proposed, which lengthened the combustor by placing the forward part of it in front of the compressor outer rim. While not as small as the original HeS 3 design, the 3b was nevertheless fairly compact. The 3b first ran in July 1939 (some references say in May), and was air-tested under the Heinkel He 118 dive bomber prototype. The original 3b engine soon burned out, but

5481-428: The fall of 1933 when I was in my seventh semester at Göttingen University. I didn't know that many people before me had the same thought." Unlike Whittle, von Ohain had the significant advantage of being supported by an aircraft manufacturer, Heinkel, who funded his work. When in 1935 von Ohain designed his overall engine layout, he based it for compactness on a centrifugal impeller (centrifugal or radial compressor) and

5568-475: 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

5655-441: 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

5742-401: 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

5829-476: The major centers for aeronautical research, with Ohain having attended lectures by Ludwig Prandtl . In 1933, while still a student, he conceived what he called "an engine that did not require a propeller ". After receiving his PhD in 1935, Ohain became the junior assistant of Robert Wichard Pohl , then director of the Physical Institute of the university. In 1936, while working for Pohl, Ohain registered

5916-594: The mind of Paul Bevilaqua , one of his students at WP-AFB , from math to engineering, which later enabled Bevilaqua to invent the Rolls-Royce LiftSystem for the JSF F35B STOVL : "in school I learned how to move the pieces, and Hans taught me how to play chess". Ohain also showed Bevilaqua "what those TS-diagrams actually mean". Ohain retired from Wright-Patterson in 1979 and took up an associate professor position teaching propulsion and thermodynamics at

6003-641: The nearby University of Dayton , spending winter sessions from 1981 to 1983 teaching the same subjects at the University of Florida . Ohain continued at the University of Dayton until 1992, when concerns about his health prompted a move with his wife, Hanny, to Melbourne, Florida . During his career, Ohain won many engineering and management awards, including (among others) the American Institute of Aeronautics and Astronautics (AIAA) Goddard Astronautics Award,

6090-402: 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

6177-454: The same period that Whittle was building his WU engine in Britain. Their turbojet designs have been said by some to be an example of simultaneous invention. However, von Ohain explains in his biography that, in 1935, while his own patent was being prepared (and before he had begun construction of an engine), his lawyer gave him a copy of Whittle's patent, which he read and critiqued. As a result, he

6264-468: 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

6351-446: 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

6438-535: 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

6525-443: The turbine, sending flames shooting out from the exhaust duct. The lack of combustion before the turbine contributed to the engine being unable to run without the assistance of the electric motor which subsequently overheated. According to von Ohain, "My interest in jet engines began in about 1933. I found that the elegance of flying was spoiled by the enormous vibrations and noise from the piston engine/propeller combination. I came to

6612-412: 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

6699-464: 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

6786-555: The turbojet engine." Born in Dessau , Germany, Ohain finished high school in 1930 at the Arndt-Gymnasium in Dahlem and earned a PhD in physics in 1935 at the University of Göttingen , with his thesis entitled An Interference Light Relay for White Light on an optical microphone to record sound directly to film, which led to his first patent. The University of Göttingen was then one of

6873-528: The wings to provide lift for VTOL aircraft. A small amount of high-pressure air is blown into a venturi , which in turn sucks a much larger volume of air along with it, thus leading to "thrust augmentation". The concept was used in the Rockwell XFV-12 experimental aircraft, although the market interest in VTOL aircraft was short-lived. He participated in several other patents. Ohain was the influence in shifting

6960-459: Was an excellent idea." The He-S3 turbine was test flown by Erich Warsitz and Walter Künzel in a Heinkel He 118 , providing additional throttled thrust to the conventional engine. While work on the HeS 1 continued, the Pohl-Ohain team had already moved on to the design of a flight-quality engine, the HeS 3 . The major differences were the use of machined compressor and turbine stages, replacing

7047-739: Was brought to the United States by Operation Paperclip and went to work for the United States Air Force at Wright-Patterson Air Force Base . In 1956 he was made the Director of the Air Force Aeronautical Research Laboratory and by 1975 he was the Chief Scientist of the Aero Propulsion Laboratory there. During his work at Wright-Patterson, Ohain continued his own personal work on various topics. In

7134-442: Was forced to modify his own application so as not to infringe on Whittle's design. The core of Ohain's first jet engine, the Heinkel HeS 1 , which he described as his "hydrogen test engine," was run "in March or early April" according to Ohain (although Ernst Heinkel's diaries record it as September 1937). Work on the hydrogen test engine continued, but the engine required modifications to fix overtemperature problems and to fit

7221-424: 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

7308-484: Was so impressed by the concept that he arranged the transfer to the project of Adolph Müller from Junkers , who was developing an axial compressor -powered design, renamed as the Heinkel HeS 30 . Müller left Junkers after they purchased the Junkers Motoren company, who had their own project under way, which by this time was known as the Junkers Jumo 004 . Meanwhile, BMW was making good progress with its own design,

7395-401: Was still not powerful enough for flight. According to von Ohain, "We experimented with various combinations to modify the compressor diffuser and turbine nozzle vanes to increase thrust sufficiently to qualify the aircraft for the first flight demonstration. We found that a small diffuser behind the engine with a collar and splitter to divert flows functioned better than a high speed flow through

7482-580: 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

7569-427: 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

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