History of the jet engine
Encyclopedia
The jet engine has a long history, from early steam devices in the 2nd century BCE to the modern turbofans and scramjets.
around 150 BCE. This device used steam power directed through two nozzles so as to cause a sphere to spin rapidly on its axis. So far as is known, it was not used for supplying mechanical power, and the potential practical applications of this invention were not recognized. It was simply considered a curiosity.
Jet propulsion only literally and figuratively took off with the invention of the rocket
by the Chinese in the 13th century fireworks
but gradually progressed to propel formidable weaponry; and there the technology stalled for hundreds of years.
Archytas
, the founder of mathematical mechanics, as described in the writings of Aulus Gellius
five centuries after him, was reputed to have designed and built the first artificial, self-propelled flying device. This device was a bird-shaped model propelled by a jet of what was probably steam, said to have actually flown some 200 meters.
Ottoman Lagari Hasan Çelebi
is said to have taken off in 1633 with what was described to be a cone-shaped rocket and then to have glided with wings into a successful landing, winning a position in the Ottoman army. However, this was essentially a stunt. The problem was that rockets are simply too inefficient at low speeds to be useful for general aviation.
The earliest attempts at airbreathing jet engines were hybrid designs in which an external power source first compressed air, which was then mixed with fuel and burned for jet thrust. In one such system, called a thermojet by Secondo Campini
but more commonly, motorjet
, the air was compressed by a fan driven by a conventional piston engine. Examples include the Caproni Campini N.1 and the Japanese Tsu-11
engine intended to power Ohka
kamikaze planes towards the end of World War II
. None were entirely successful and the CC.2 ended up being slower than the same design with a traditional engine and propeller
combination.
In 1913 René Lorin
came up with a form of jet engine, the subsonic pulsejet, which would have been somewhat more efficient, but he had no way to achieve high enough speeds for it to operate, and the concept remained theoretical for quite some time.
Even before the start of World War II, engineers were beginning to realize that the piston engine was self-limiting in terms of the maximum performance which could be attained; the limit was due to issues related to propulsive efficiency
, which declined as blade tips approached the speed of sound
. If engine, and thus aircraft, performance were ever to increase beyond such a barrier, a way would have to be found to radically improve the design of the piston engine, or a wholly new type of powerplant would have to be developed. This was the motivation behind the development of the gas turbine engine, commonly called a "jet" engine, which would become almost as revolutionary to aviation as the Wright brothers
' first flight.
The key to a practical jet engine was the gas turbine, used to extract energy from the engine itself to drive the compressor
. The gas turbine
was not an idea developed in the 1930s: the patent for a stationary turbine was granted to John Barber in England in 1791. The first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling
. Limitations in design and practical engineering and metallurgy prevented such engines reaching manufacture. The main problems were safety, reliability, weight and, especially, sustained operation.
In Hungary
, Albert Fonó
in 1915 devised a solution for increasing the range of artillery, comprising a gun-launched projectile which was to be united with a ramjet propulsion unit. This was to make it possible to obtain a long range with low initial muzzle velocities, allowing heavy shells to be fired from relatively lightweight guns. Fonó submitted his invention to the Austro-Hungarian Army but the proposal was rejected. In 1928 he applied for a German patent on aircraft powered by supersonic ramjets, and this was awarded in 1932.
The first patent for using a gas turbine to power an aircraft was filed in 1921 by Frenchman Maxime Guillaume
. His engine was an axial-flow turbojet.
In 1923, Edgar Buckingham of the US National Bureau of Standard published a report expressing scepticism that jet engines would be economically competitive with prop driven aircraft at the low altitudes and airspeeds of the period: "there
does not appear to be, at present, any prospect whatever that jet propulsion of the sort here considered will ever be of practical value, even for military purposes."
Instead, by the 1930s, the piston engine in its many different forms (rotary and static radial, aircooled and liquid-cooled inline) was the only type of powerplant available to aircraft designers. This was acceptable as long as only low performance aircraft were required, and indeed all that were available.
In 1928, RAF College Cranwell cadet Frank Whittle
formally submitted his ideas for a turbo-jet 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 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 would later concentrate on the simpler centrifugal compressor only, for a variety of practical reasons. Whittle had his first engine running in April 1937. It was liquid-fuelled, and included a self-contained fuel pump. Whittle's team experienced near-panic when the engine would not stop, accelerating even after the fuel was switched off. It turned out that fuel had leaked into the engine and accumulated in pools. So the engine would not stop until all the leaked fuel had burned off. Whittle was unable to interest the government in his invention, and development continued at a slow pace.
In 1935 Hans von Ohain
started work on a similar design in Germany
, apparently unaware of Whittle's work. His first device was strictly experimental and could only run under external power, but he was able to demonstrate the basic concept. Ohain was then introduced to Ernst Heinkel
, one of the larger aircraft industrialists of the day, who immediately saw the promise of the design. Heinkel had recently purchased the Hirth engine company, and Ohain and his master machinist Max Hahn were set up there as a new division of the Hirth company. They had their first HeS 1
centrifugal engine running by September 1937. Unlike Whittle's design, Ohain used hydrogen
as fuel, supplied under external pressure. Their subsequent designs culminated in the gasoline-fuelled HeS 3
of 1,100 lbf (5 kN), which was fitted to Heinkel's simple and compact He 178
airframe and flown by Erich Warsitz
in the early morning of August 27, 1939, from Rostock
-Marienehe aerodrome, an impressively short time for development. The He 178 was the world's first jet plane.
The world's first turboprop
was the Jendrassik Cs-1
designed by the Hungarian mechanical engineer György Jendrassik
. It was produced and tested in the Ganz
factory in Budapest
between 1938 and 1942. It was planned to fit to the Varga RMI-1 X/H twin-engined reconnaissance bomber designed by László Varga in 1940, but the program was cancelled. Jendrassik had also designed a small-scale 75 kW turboprop in 1937.
Whittle's engine was starting to look useful, and his Power Jets
Ltd. started receiving Air Ministry
money. In 1941 a flyable version of the engine called the W.1, capable of 1000 lbf (4 kN) of thrust, was fitted to the Gloster E28/39 airframe
specially built for it, and first flew on May 15, 1941 at RAF Cranwell
.
A Scottish aircraft engine designer, Frank Halford
, working from Whittle's ideas developed a "straight through" version of the centrifugal jet; his design became the de Havilland Goblin.
One problem with both of these early designs, which are called centrifugal-flow
engines, was that the compressor worked by "throwing" (accelerating) air outward from the central intake to the outer periphery of the engine, where the air was then compressed by a divergent duct setup, converting its velocity into pressure. An advantage of this design was that it was already well understood, having been implemented in centrifugal supercharger
s, then in widespread use on piston engines. However, given the early technological limitations on the shaft speed of the engine, the compressor needed to have a very large diameter to produce the power required. This meant that the engines had a large frontal area, which made it less useful as an aircraft powerplant due to drag. A further disadvantage was that the air flow had to be "bent" to flow rearwards through the combustion section and to the turbine and tailpipe, adding complexity and lowering efficiency. Nevertheless, these types of engines had the major advantages of light weight, simplicity and reliability, and development rapidly progressed to practical airworthy designs.
Austria
n Anselm Franz
of Junkers' engine division (Junkers Motoren or Jumo) addressed these problems with the introduction of the axial-flow compressor. Essentially, this is a turbine in reverse. Air coming in the front of the engine is blown towards the rear of the engine by a fan stage (convergent ducts), where it is crushed against a set of non-rotating blades called stators (divergent ducts). The process is nowhere near as powerful as the centrifugal compressor, so a number of these pairs of fans and stators are placed in series to get the needed compression. Even with all the added complexity, the resulting engine is much smaller in diameter and thus, more aerodynamic. Jumo was assigned the next engine number in the RLM
numbering sequence, 4, and the result was the Jumo 004
engine. After many lesser technical difficulties were solved, mass production of this engine started in 1944 as a powerplant for the world's first jet-fighter aircraft, the Messerschmitt Me 262
(and later the world's first jet-bomber aircraft, the Arado Ar 234
). A variety of reasons conspired to delay the engine's availability, this delay caused the fighter to arrive too late to decisively impact Germany's position in World War II. Nonetheless, it will be remembered as the first use of jet engines in service.
In the UK, their first axial-flow engine, the Metrovick F.2
, ran in 1941 and was first flown in 1943. Although more powerful than the centrifugal designs at the time, the Ministry considered its complexity and unreliability a drawback in wartime. The work at Metrovick led to the Armstrong Siddeley Sapphire engine which would be built in the US as the J65.
Centrifugal-flow engines have improved since their introduction. With improvements in bearing technology the shaft speed of the engine was increased, greatly reducing the diameter of the centrifugal compressor. The short engine length remains an advantage of this design, particularly for use in helicopters where overall size is more important than frontal area. Also as their engine components are more robust they are less liable to foreign object damage
than axial-flow compressor engines.
Although German designs were more advanced aerodynamically, the combination of simplicity and the lack of requisite rare metals for the necessary advanced metallurgy (such as tungsten
, chromium
and titanium
) for high-stress components such as turbine blades and bearing
s, etc.) meant that the later produced German engines had a short service life and had to be changed after 10–25 hours. British engines were also widely manufactured under license in the US (see Tizard Mission
), and were sold to Soviet Russia who reverse engineered them with the Nene
going on to power the famous MiG-15. American and Soviet designs, independent axial-flow types for the most part, would strive to attain superior performance until the 1960s, although the General Electric J47
provided excellent service in the F-86 Sabre
in the 1950s.
By the 1950s the jet engine was almost universal in combat aircraft, with the exception of cargo, liaison and other specialty types. By this point some of the British designs were already cleared for civilian use, and had appeared on early models like the de Havilland Comet
and Avro Canada Jetliner. By the 1960s all large civilian aircraft were also jet powered, leaving the piston engine in such low-cost niche roles such as cargo
flights.
Relentless improvements in the turboprop
pushed the piston engine (an internal combustion engine) out of the mainstream entirely, leaving it serving only the smallest general aviation
designs and some use in drone aircraft. The ascension of the jet engine to almost universal use in aircraft took well under twenty years.
However, the story was not quite at an end, for the efficiency of turbojet engines was still rather worse than piston engines, but by the 1970s with the advent of high bypass jet engines, an innovation not foreseen by the early commentators like Edgar Buckingham, at high speeds and high altitudes that seemed absurd to them, only then did the fuel efficiency finally exceed that of the best piston and propeller engines, and the dream of fast, safe, economical travel around the world finally arrived, and their dour, if well founded for the time, predictions that jet engines would never amount to much, were killed forever.
Precursors
Jet engines can be dated back to the invention of the aeolipileAeolipile
An aeolipile , also known as a Hero engine, is a rocket style jet engine which spins when heated. In the 1st century AD, Hero of Alexandria described the device, and many sources give him the credit for its invention.The aeolipile Hero described is considered to be the first recorded steam engine...
around 150 BCE. This device used steam power directed through two nozzles so as to cause a sphere to spin rapidly on its axis. So far as is known, it was not used for supplying mechanical power, and the potential practical applications of this invention were not recognized. It was simply considered a curiosity.
Jet propulsion only literally and figuratively took off with the invention of the rocket
Rocket
A rocket is a missile, spacecraft, aircraft or other vehicle which obtains thrust from a rocket engine. In all rockets, the exhaust is formed entirely from propellants carried within the rocket before use. Rocket engines work by action and reaction...
by the Chinese in the 13th century fireworks
Fireworks
Fireworks are a class of explosive pyrotechnic devices used for aesthetic and entertainment purposes. The most common use of a firework is as part of a fireworks display. A fireworks event is a display of the effects produced by firework devices...
but gradually progressed to propel formidable weaponry; and there the technology stalled for hundreds of years.
Archytas
Archytas
Archytas was an Ancient Greek philosopher, mathematician, astronomer, statesman, and strategist. He was a scientist of the Pythagorean school and famous for being the reputed founder of mathematical mechanics, as well as a good friend of Plato....
, the founder of mathematical mechanics, as described in the writings of Aulus Gellius
Aulus Gellius
Aulus Gellius , was a Latin author and grammarian, who was probably born and certainly brought up in Rome. He was educated in Athens, after which he returned to Rome, where he held a judicial office...
five centuries after him, was reputed to have designed and built the first artificial, self-propelled flying device. This device was a bird-shaped model propelled by a jet of what was probably steam, said to have actually flown some 200 meters.
Ottoman Lagari Hasan Çelebi
Lagari Hasan Çelebi
Lagari Hasan Çelebi was a legendary Ottoman aviator who, according to an account written by Evliya Çelebi, made a successful manned rocket flight.-Account:...
is said to have taken off in 1633 with what was described to be a cone-shaped rocket and then to have glided with wings into a successful landing, winning a position in the Ottoman army. However, this was essentially a stunt. The problem was that rockets are simply too inefficient at low speeds to be useful for general aviation.
The earliest attempts at airbreathing jet engines were hybrid designs in which an external power source first compressed air, which was then mixed with fuel and burned for jet thrust. In one such system, called a thermojet by Secondo Campini
Secondo Campini
Secondo Campini was an Italian engineer and one of the pioneers of the jet engine.Campini was born at Bologna, Emilia-Romagna. In 1931 he wrote a proposal for the Italian Air Ministry on the value of jet propulsion and in 1932 demonstrated a jet-powered boat in Venice...
but more commonly, motorjet
Motorjet
A motorjet is a rudimentary type of jet engine which is sometimes referred to as thermojet, a term now commonly used to describe a particular and completely unrelated pulsejet design.- Design :...
, the air was compressed by a fan driven by a conventional piston engine. Examples include the Caproni Campini N.1 and the Japanese Tsu-11
Tsu-11
The Tsu-11 was a primitive, motorjet-style jet engine produced in small numbers in Japan in the closing stages of World War II. It was principally designed to propel the Japanese Ohka flying bomb, a kamikaze weapon....
engine intended to power Ohka
Ohka
The Yokosuka MXY-7 Ohka was a purpose-built, rocket powered human-guided anti-shipping kamikaze attack plane employed by Japan towards the end of World War II...
kamikaze planes towards the end of World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. None were entirely successful and the CC.2 ended up being slower than the same design with a traditional engine and propeller
Propeller (aircraft)
Aircraft propellers or airscrews convert rotary motion from piston engines or turboprops to provide propulsive force. They may be fixed or variable pitch. Early aircraft propellers were carved by hand from solid or laminated wood with later propellers being constructed from metal...
combination.
René Lorin
René Lorin , a graduate of the Ecole Centrale Paris, invented the ramjet. In 1908 he patented a subsonic ramjet design.Lorin published the principles of a ramjet in articles in the journal L'Aérophile from 1908 to 1913, expressing the idea that the exhaust from internal combustion engines could be...
came up with a form of jet engine, the subsonic pulsejet, which would have been somewhat more efficient, but he had no way to achieve high enough speeds for it to operate, and the concept remained theoretical for quite some time.
Even before the start of World War II, engineers were beginning to realize that the piston engine was self-limiting in terms of the maximum performance which could be attained; the limit was due to issues related to propulsive efficiency
Propulsive efficiency
In aircraft and rocket design, overall propulsive efficiency \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 the...
, which declined as blade tips approached the speed of sound
Speed of sound
The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....
. If engine, and thus aircraft, performance were ever to increase beyond such a barrier, a way would have to be found to radically improve the design of the piston engine, or a wholly new type of powerplant would have to be developed. This was the motivation behind the development of the gas turbine engine, commonly called a "jet" engine, which would become almost as revolutionary to aviation as the Wright brothers
Wright brothers
The Wright brothers, Orville and Wilbur , were two Americans credited with inventing and building the world's first successful airplane and making the first controlled, powered and sustained heavier-than-air human flight, on December 17, 1903...
' first flight.
Gas compressor
A gas compressor is a mechanical device that increases the pressure of a gas by reducing its volume.Compressors are similar to pumps: both increase the pressure on a fluid and both can transport the fluid through a pipe. As gases are compressible, the compressor also reduces the volume of a gas...
. The gas turbine
Gas turbine
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between....
was not an idea developed in the 1930s: the patent for a stationary turbine was granted to John Barber in England in 1791. The first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Ægidius Elling
Ægidius Elling
Jens William Ægidius Elling was a Norwegian researcher, inventor and pioneer of gas turbine who is considered to be the father of the gas turbine. He built the first gas turbine that was able to produce more power than needed to run its own components.Elling was born in and grew up in Oslo, Norway...
. Limitations in design and practical engineering and metallurgy prevented such engines reaching manufacture. The main problems were safety, reliability, weight and, especially, sustained operation.
In Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
, Albert Fonó
Albert Fonó
Albert Fonó , was a Hungarian mechanical engineer who was one of the early pioneers of turbojet and ramjet propulsion and was first to patent a ramjet engine in 1928, ....
in 1915 devised a solution for increasing the range of artillery, comprising a gun-launched projectile which was to be united with a ramjet propulsion unit. This was to make it possible to obtain a long range with low initial muzzle velocities, allowing heavy shells to be fired from relatively lightweight guns. Fonó submitted his invention to the Austro-Hungarian Army but the proposal was rejected. In 1928 he applied for a German patent on aircraft powered by supersonic ramjets, and this was awarded in 1932.
The first patent for using a gas turbine to power an aircraft was filed in 1921 by Frenchman Maxime Guillaume
Maxime Guillaume
In aerospace, Maxime Guillaume held a French patent for a turbojet engine in 1921.The first patent for using 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...
. His engine was an axial-flow turbojet.
In 1923, Edgar Buckingham of the US National Bureau of Standard published a report expressing scepticism that jet engines would be economically competitive with prop driven aircraft at the low altitudes and airspeeds of the period: "there
does not appear to be, at present, any prospect whatever that jet propulsion of the sort here considered will ever be of practical value, even for military purposes."
Instead, by the 1930s, the piston engine in its many different forms (rotary and static radial, aircooled and liquid-cooled inline) was the only type of powerplant available to aircraft designers. This was acceptable as long as only low performance aircraft were required, and indeed all that were available.
Pre World War II
Frank Whittle
Air Commodore Sir Frank Whittle, OM, KBE, CB, FRS, Hon FRAeS was a British Royal Air Force engineer officer. He is credited with independently inventing the turbojet engine Air Commodore Sir Frank Whittle, OM, KBE, CB, FRS, Hon FRAeS (1 June 1907 – 9 August 1996) was a British Royal Air...
formally submitted his ideas for a turbo-jet 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 a two-stage axial compressor
Axial compressor
Axial compressors are rotating, airfoil-based compressors in which the working fluid principally flows parallel to the axis of rotation. This is in contrast with other rotating compressors such as centrifugal, axi-centrifugal and mixed-flow compressors where the air may enter axially but will have...
feeding a single-sided centrifugal compressor. Practical axial compressors were made possible by ideas from A.A.Griffith
Alan Arnold Griffith
Alan Arnold Griffith was an English engineer, who, among many other contributions, is best known for his work on stress and fracture in metals that is now known as metal fatigue, as well as being one of the first to develop a strong theoretical basis for the jet engine.-Early work:A. A...
in a seminal paper in 1926 ("An Aerodynamic Theory of Turbine Design"). Whittle would later concentrate on the simpler centrifugal compressor only, for a variety of practical reasons. Whittle had his first engine running in April 1937. It was liquid-fuelled, and included a self-contained fuel pump. Whittle's team experienced near-panic when the engine would not stop, accelerating even after the fuel was switched off. It turned out that fuel had leaked into the engine and accumulated in pools. So the engine would not stop until all the leaked fuel had burned off. Whittle was unable to interest the government in his invention, and development continued at a slow pace.
Hans von Ohain
Hans Joachim Pabst von Ohain was a German engineer, one of the inventors of jet propulsion.Frank Whittle, who patented in 1930 in the United Kingdom, and Hans von Ohain, who patented in 1936 in Germany, developed the concept independently during the late 1930s...
started work on a similar design in Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
, apparently unaware of Whittle's work. His first device was strictly experimental and could only run under external power, but he was able to demonstrate the basic concept. Ohain was then introduced to Ernst Heinkel
Ernst Heinkel
Dr. Ernst Heinkel was a German aircraft designer, manufacturer, Wehrwirtschaftführer in the Third Reich, and member of the Nazi party. His company Heinkel Flugzeugwerke produced the Heinkel He 178, the world's first turbojet aircraft and jet plane, and the Heinkel He 176, the first rocket aircraft...
, one of the larger aircraft industrialists of the day, who immediately saw the promise of the design. Heinkel had recently purchased the Hirth engine company, and Ohain and his master machinist Max Hahn were set up there as a new division of the Hirth company. They had their first HeS 1
Heinkel HeS 1
The Heinkel HeS 1 was Germany's first jet engine, which was a stationary test item that ran on hydrogen.-History:In 1933, Hans von Ohain wrote his PhD thesis at the University of Göttingen on the topic of an optical microphone that could be used to record sound directly to film. Siemens bought the...
centrifugal engine running by September 1937. Unlike Whittle's design, Ohain used hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
as fuel, supplied under external pressure. Their subsequent designs culminated in the gasoline-fuelled HeS 3
Heinkel HeS 3
The Heinkel HeS 3 was the world's first operational jet engine to power an aircraft. Designed by Hans von Ohain while working at Heinkel, the engine first flew as the primary power of the Heinkel He 178, piloted by Erich Warsitz on 27 August 1939...
of 1,100 lbf (5 kN), which was fitted to Heinkel's simple and compact He 178
Heinkel He 178
|-See also:*List of firsts in aviation-Bibliography:* Warsitz, Lutz: The First Jet Pilot - The Story of German Test Pilot Erich Warsitz, Pen and Sword Books Ltd., England, 2009, ISBN 9781844158188.-External links:...
airframe and flown by Erich Warsitz
Erich Warsitz
Erich Warsitz was a German test pilot of the 1930s. He held the rank of Flight-Captain in the Luftwaffe and was selected by the Reich Air Ministry as chief test pilot at Peenemünde West...
in the early morning of August 27, 1939, from Rostock
Rostock
Rostock -Early history:In the 11th century Polabian Slavs founded a settlement at the Warnow river called Roztoc ; the name Rostock is derived from that designation. The Danish king Valdemar I set the town aflame in 1161.Afterwards the place was settled by German traders...
-Marienehe aerodrome, an impressively short time for development. The He 178 was the world's first jet plane.
The world's first turboprop
Turboprop
A turboprop engine is a type of turbine engine which drives an aircraft propeller using a reduction gear.The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...
was the Jendrassik Cs-1
Jendrassik Cs-1
The Jendrassik Cs-1 was the world's first working turboprop engine. It was designed by Hungarian engineer György Jendrassik in 1937, and was intended to power a Hungarian twin-engine heavy fighter, the RMI-1.-Design and development:...
designed by the Hungarian mechanical engineer György Jendrassik
György Jendrassik
György Jendrassik , Hungarian physicist and mechanical engineer.Jendrassik completed his education at Budapest's József Technical University, then at the University of Berlin attended lectures of the famous physicists Einstein and Planck. In 1922 he obtained his diploma in mechanical engineering in...
. It was produced and tested in the Ganz
Ganz
The Ganz electric works in Budapest is probably best known for the manufacture of tramcars, but was also a pioneer in the application of three-phase alternating current to electric railways. Ganz also made / makes: ships , bridge steel structures , high voltage equipment...
factory in Budapest
Budapest
Budapest is the capital of Hungary. As the largest city of Hungary, it is the country's principal political, cultural, commercial, industrial, and transportation centre. In 2011, Budapest had 1,733,685 inhabitants, down from its 1989 peak of 2,113,645 due to suburbanization. The Budapest Commuter...
between 1938 and 1942. It was planned to fit to the Varga RMI-1 X/H twin-engined reconnaissance bomber designed by László Varga in 1940, but the program was cancelled. Jendrassik had also designed a small-scale 75 kW turboprop in 1937.
Whittle's engine was starting to look useful, and his Power Jets
Power Jets
Power Jets Ltd was a United Kingdom company set up by Frank Whittle for the purpose of designing and manufacturing jet engines.-History:Founded on January 27, 1936, the company consisted of Whittle, Rolf Dudley-Williams, James Collingwood Tinling, and Lancelot Law Whyte of investment bankers O T...
Ltd. started receiving Air Ministry
Air Ministry
The Air Ministry was a department of the British Government with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964...
money. In 1941 a flyable version of the engine called the W.1, capable of 1000 lbf (4 kN) of thrust, was fitted to the Gloster E28/39 airframe
Airframe
The airframe of an aircraft is its mechanical structure. It is typically considered to include fuselage, wings and undercarriage and exclude the propulsion system...
specially built for it, and first flew on May 15, 1941 at RAF Cranwell
RAF Cranwell
RAF Cranwell is a Royal Air Force station in Lincolnshire close to the village of Cranwell, near Sleaford. It is currently commanded by Group Captain Dave Waddington...
.
Frank Halford
Major Frank Bernard Halford CBE FRAeS was an English aircraft engine designer.-Career:Educated at Felsted, In 1913 he left the University of Nottingham before graduating to learn to fly at Brooklands and Bristol Flying School and became a flight instructor using Bristol Boxkites.He served in the...
, working from Whittle's ideas developed a "straight through" version of the centrifugal jet; his design became the de Havilland Goblin.
One problem with both of these early designs, which are called centrifugal-flow
Centrifugal compressor
Centrifugal compressors, sometimes termed radial compressors, are a sub-class of dynamic axisymmetric work-absorbing turbomachinery.The idealized compressive dynamic turbo-machine achieves a pressure rise by adding kinetic energy/velocity to a continuous flow of fluid through the rotor or impeller...
engines, was that the compressor worked by "throwing" (accelerating) air outward from the central intake to the outer periphery of the engine, where the air was then compressed by a divergent duct setup, converting its velocity into pressure. An advantage of this design was that it was already well understood, having been implemented in centrifugal supercharger
Supercharger
A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...
s, then in widespread use on piston engines. However, given the early technological limitations on the shaft speed of the engine, the compressor needed to have a very large diameter to produce the power required. This meant that the engines had a large frontal area, which made it less useful as an aircraft powerplant due to drag. A further disadvantage was that the air flow had to be "bent" to flow rearwards through the combustion section and to the turbine and tailpipe, adding complexity and lowering efficiency. Nevertheless, these types of engines had the major advantages of light weight, simplicity and reliability, and development rapidly progressed to practical airworthy designs.
Austria
Austria , officially the Republic of Austria , is a landlocked country of roughly 8.4 million people in Central Europe. It is bordered by the Czech Republic and Germany to the north, Slovakia and Hungary to the east, Slovenia and Italy to the south, and Switzerland and Liechtenstein to the...
n Anselm Franz
Anselm Franz
Dr. Anselm Franz was a pioneering Austrian jet engine engineer known for the development of the Jumo 004, the world's first mass-produced turbojet engine by Nazi Germany during World War II, and his work on turboshaft designs in the U.S...
of Junkers' engine division (Junkers Motoren or Jumo) addressed these problems with the introduction of the axial-flow compressor. Essentially, this is a turbine in reverse. Air coming in the front of the engine is blown towards the rear of the engine by a fan stage (convergent ducts), where it is crushed against a set of non-rotating blades called stators (divergent ducts). The process is nowhere near as powerful as the centrifugal compressor, so a number of these pairs of fans and stators are placed in series to get the needed compression. Even with all the added complexity, the resulting engine is much smaller in diameter and thus, more aerodynamic. Jumo was assigned the next engine number in the RLM
Reich Air Ministry
thumb|300px|The Ministry of Aviation, December 1938The Ministry of Aviation was a government department during the period of Nazi Germany...
numbering sequence, 4, and the result was the Jumo 004
Junkers Jumo 004
The Jumo 004 was the world's first turbojet engine in production and operational use, and the first successful axial compressor jet engine ever built. Some 8,000 units were manufactured by Junkers in Germany during late World War II and powered the operational Messerschmitt Me 262 jet fighter,...
engine. After many lesser technical difficulties were solved, mass production of this engine started in 1944 as a powerplant for the world's first jet-fighter aircraft, the Messerschmitt Me 262
Messerschmitt Me 262
The Messerschmitt Me 262 Schwalbe was the world's first operational jet-powered fighter aircraft. Design work started before World War II began, but engine problems prevented the aircraft from attaining operational status with the Luftwaffe until mid-1944...
(and later the world's first jet-bomber aircraft, the Arado Ar 234
Arado Ar 234
The Arado Ar 234 was the world's first operational jet-powered bomber, built by the German Arado company in the closing stages of World War II. Produced in very limited numbers, it was used almost entirely in the reconnaissance role, but in its few uses as a bomber it proved to be nearly impossible...
). A variety of reasons conspired to delay the engine's availability, this delay caused the fighter to arrive too late to decisively impact Germany's position in World War II. Nonetheless, it will be remembered as the first use of jet engines in service.
In the UK, their first axial-flow engine, the Metrovick F.2
Metrovick F.2
The Metropolitan-Vickers F.2 was an early turbojet engine and the first British design to be based on an axial-flow compressor. It was considered too unreliable for use during the war, and never entered production...
, ran in 1941 and was first flown in 1943. Although more powerful than the centrifugal designs at the time, the Ministry considered its complexity and unreliability a drawback in wartime. The work at Metrovick led to the Armstrong Siddeley Sapphire engine which would be built in the US as the J65.
Post World War II
Following the end of the war the German jet aircraft and jet engines were extensively studied by the victorious allies and contributed to work on early Soviet and US jet fighters. The legacy of the axial-flow engine is seen in the fact that practically all jet engines on fixed wing aircraft have had some inspiration from this design.Centrifugal-flow engines have improved since their introduction. With improvements in bearing technology the shaft speed of the engine was increased, greatly reducing the diameter of the centrifugal compressor. The short engine length remains an advantage of this design, particularly for use in helicopters where overall size is more important than frontal area. Also as their engine components are more robust they are less liable to foreign object damage
Foreign object damage
Foreign Object Debris is a substance, debris or article alien to a vehicle or system which would potentially cause damage.Foreign Object Damage is any damage attributed to a foreign object that can be expressed in physical or economic terms that may or may not degrade the product's required...
than axial-flow compressor engines.
Although German designs were more advanced aerodynamically, the combination of simplicity and the lack of requisite rare metals for the necessary advanced metallurgy (such as tungsten
Tungsten
Tungsten , also known as wolfram , is a chemical element with the chemical symbol W and atomic number 74.A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as...
, chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
and titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
) for high-stress components such as turbine blades and bearing
Bearing (mechanical)
A bearing is a device to allow constrained relative motion between two or more parts, typically rotation or linear movement. Bearings may be classified broadly according to the motions they allow and according to their principle of operation as well as by the directions of applied loads they can...
s, etc.) meant that the later produced German engines had a short service life and had to be changed after 10–25 hours. British engines were also widely manufactured under license in the US (see Tizard Mission
Tizard Mission
The Tizard Mission officially the British Technical and Scientific Mission was a British delegation that visited the United States during the Second World War in order to obtain the industrial resources to exploit the military potential of the research and development work completed by the UK up...
), and were sold to Soviet Russia who reverse engineered them with the Nene
Rolls-Royce Nene
|-See also:-References:NotesBibliography* Bridgman, L, Jane's fighting aircraft of World War II. Crescent. ISBN 0-517-67964-7-External links:* *...
going on to power the famous MiG-15. American and Soviet designs, independent axial-flow types for the most part, would strive to attain superior performance until the 1960s, although the General Electric J47
General Electric J47
|-Specifications :-Nuclear-powered version – The X39:In the 1950s, interest in the development of nuclear-powered aircraft led GE to experiment with two nuclear-powered gas turbine designs, one based on the J47, and another new and much larger engine called the X211.The design based on the J47...
provided excellent service in the F-86 Sabre
F-86 Sabre
The North American F-86 Sabre was a transonic jet fighter aircraft. Produced by North American Aviation, the Sabre is best known as America's first swept wing fighter which could counter the similarly-winged Soviet MiG-15 in high speed dogfights over the skies of the Korean War...
in the 1950s.
By the 1950s the jet engine was almost universal in combat aircraft, with the exception of cargo, liaison and other specialty types. By this point some of the British designs were already cleared for civilian use, and had appeared on early models like the de Havilland Comet
De Havilland Comet
The de Havilland DH 106 Comet was the world's first commercial jet airliner to reach production. Developed and manufactured by de Havilland at the Hatfield, Hertfordshire, United Kingdom headquarters, it first flew in 1949 and was a landmark in aeronautical design...
and Avro Canada Jetliner. By the 1960s all large civilian aircraft were also jet powered, leaving the piston engine in such low-cost niche roles such as cargo
Cargo
Cargo is goods or produce transported, generally for commercial gain, by ship, aircraft, train, van or truck. In modern times, containers are used in most intermodal long-haul cargo transport.-Marine:...
flights.
Relentless improvements in the turboprop
Turboprop
A turboprop engine is a type of turbine engine which drives an aircraft propeller using a reduction gear.The gas turbine is designed specifically for this application, with almost all of its output being used to drive the propeller...
pushed the piston engine (an internal combustion engine) out of the mainstream entirely, leaving it serving only the smallest general aviation
General aviation
General aviation is one of the two categories of civil aviation. It refers to all flights other than military and scheduled airline and regular cargo flights, both private and commercial. General aviation flights range from gliders and powered parachutes to large, non-scheduled cargo jet flights...
designs and some use in drone aircraft. The ascension of the jet engine to almost universal use in aircraft took well under twenty years.
However, the story was not quite at an end, for the efficiency of turbojet engines was still rather worse than piston engines, but by the 1970s with the advent of high bypass jet engines, an innovation not foreseen by the early commentators like Edgar Buckingham, at high speeds and high altitudes that seemed absurd to them, only then did the fuel efficiency finally exceed that of the best piston and propeller engines, and the dream of fast, safe, economical travel around the world finally arrived, and their dour, if well founded for the time, predictions that jet engines would never amount to much, were killed forever.