He 162

The Heinkel He 162 Volksjäger (People's Fighter) was the second jet engined fighter aircraft to be fielded by the Luftwaffe in WWII. It was a rival to the Messerschmitt Me 262 and was the fastest of the first generation of Axis and Allied jets. Volksjäger was the official Reichsluftfahrtministerium name given to the He 162. Other names given to the plane include Salamander, which was the codename of its construction program, and Spatz, (sparrow) which was the name given to the plane by Heinkel.

Development

When the US 8th Air Force re-opened the bombing campaign on Germany in early 1944, the bombers returned to the skies along with the P-51 Mustang in escort. This changed the nature of the air war entirely; formerly German fighter units could form up for attack on the bombers unmolested, but with escort they were soon spending more time avoiding the US patrols than attacking the bombers. Changes made over the previous year to improve the fighter's bomber-killing abilities with extremely heavy guns also had the side effect of turning them into deathtraps when the much lighter Mustangs were able to easily outperform the now overweight German aircraft. The US now had both superior numbers and technology, and by the end of April the backbone of the Luftwaffe fighter groups had been broken. With few planes coming up to fight, the US fighters were let loose on the German airbases, railways and truck traffic. Logistics soon became a serious problem, maintaining aircraft in fighting condition almost impossible. What to do about this was a considerable problem for the Luftwaffe. Two camps quickly developed, both demanding the immediate introduction of large numbers of jet aircraft. One group, led by General der Jäger Adolf Galland, reasoned that superior numbers had to be countered with superior technology, and demanded that all possible effort be put into increasing the production of the Messerschmitt Me 262, even if that meant reducing production of other aircraft in the meantime. Another camp pointed out that this would likely do little to address the problem; the Me 262 was notoriously unreliable, and the existing logistics problems would mean there would simply be more of them sitting on the ground waiting for parts that would never arrive. Instead they suggested that a new design be built, one so inexpensive that if it did break it could simply be thrown away. The concept was derided by most fighter pilots, but gained significant political backing. The argument eventually came down to Galland on one side with support from Willy Messerschmidt and Kurt Tank, opposed by Reichsmarshall Goering and Armaments Minister Albert Speer. Unsurprisingly, a contract tender for a single-engined jet fighter that was suited for cheap and rapid mass production was established under the name Volksjäger ("People's Fighter"). The official RLM requirement specified a single-seat fighter, powered by a single BMW 003 and a weight of no more than two tonnes (4,400 pounds), most fighters of the era were twice that. Maximum speed was specified as 750 km/h (466 mph) at sea level, operational endurance was to be at least a half hour, and the takeoff run was to be no more than 500 meters (1,640 feet). Armament was specified as either two 20mm MG 151/30's with 100 rounds per gun, or two 30mm MK 108 with 50 rounds per gun. The requirement was sent out on 10 September 1944, with basic designs to be returned within 10 days and production to start in January.

Design

Heinkel had already been working on a series of "paper projects" for light single-engine fighters over the last year under the designation P.1073, and had gone so far as to build and test several models and conduct some wind tunnel testing. Although some of the competing designs were technically superior, with Heinkel's head start the outcome was largely a forgone conclusion. The results of the competition were announced in October 1944, only three weeks after being announced, and to no-one's surprise the Heinkel entry was selected for production. Heinkel had designed a neat, sporty-looking little aircraft, with a sleek, streamlined fuselage, a BMW 003 engine carried in a nacelle on the back of the aircraft, twin tailfins allowing the vertical tailplanes to clear the jet exhaust, a high-mounted straight wing with a shallow dihedral, an ejection seat for the pilot and tricycle landing gear that retracted into the fuselage. The plane was in the air within an astoundingly short period of time: the design was chosen on 25 September and first flew on December 6th, less than 90 days later. The first flight was fairly successful, but during a high-speed run at 840 km/h the glue holding the nose gear cover on failed and the pilot was forced to land. Other problems were noted as well, notably a pitch instability and "snaking". Neither was considered important. On a second flight on 10 December in front of various Nazi officials the glue failed again, this time on the wing. This allowed the aileron to separate, and the plane slowly rolled over and crashed, killing the pilot. An investigation into the failure revealed that the wing structure had to be re-designed for more stength, but the schedule was so tight that testing was forced to continue with the current design. Speeds were limited to 500 km/h when the second prototype flew on 22 December. This time the stability problems proved to be more serious, and were tracked to dutch roll which could be solved by reducing the dihedral. However, with the plane supposed to enter production within weeks, there was no time to change the design. Two prototypes with the strengthened wings flew on 16 January. These versions also included small attachements on the wing tips in an attempt to cure the stability problems, but these had little effect. Both were equipped with two MK 108's in the He 162A-1 bomber hunter version, but in testing the recoil proved to be too much for the wooded fuselage to handle, and plans for production turned to the A-2 fighter with two MG 151/20's instead while a redesign for added strength started as the A-3. Various changes had raised the weight over the original 2 tonne limit, but even at 2,800 kg the aircraft was still the fastest jet aircraft in the air at 890 km/h (553 mph) at sea level, and even faster at 905 km/h (562 mph) at 6,000 meters (20,000 feet).

Operations

In January 1945, the Luftwaffe formed a special "Erprobungskommando 162" He 162 test pilot evaluation group to which the first 46 aircraft were delivered. The group was based at the Luftwaffe test center at Rechlin under the command of Heinz Bär. Bär, an experienced combat pilot credited with 200 kills, familiarized himself and his group with the new airplanes. February saw deliveries of the He 162 to its first operational unit, I/JG-1, the 1st Group of Jagdgeschwader 1 (fighter squadron), which had previously flown the Focke-Wulf Fw 190. I/JG-1 was transferred to Parchim, near the Heinkel factory at Marienehe, where the pilots could pick up their new jets and start intensive training beginning in March, all while the transportation network and fuel supply of the Third Reich was collapsing under the pressure of Allied air attacks. On April 7, the USAAF bombed the field at Parchim with 134 B-17 Flying Fortresses, inflicting serious losses and damage to the infrastructure. Two days later, I/JG-1 transferred to a airfield at nearby Ludwigslust and, less than a week later, moved again to an airfield at Leck, near the Danish border. In the meantime, on April 8 the 2nd Group of JG-1 (II/JG-1) moved to the Heinkel airfield at Marienehe and started converting from Fw 190s to He 162s. The 3rd Group of JG-1 (III/JG-1) was also scheduled to convert to the He 162, but the Group was disbanded on April 24 and its personnel used to fill in the vacancies in other units. The He-162 finally saw combat in mid-April. On April 19, a captured Royal Air Force fighter pilot informed his Germans interrogators that he had been shot down by a jet fighter matching the description of a He 162. The Heinkel and its pilot were lost as well, shot down by a RAF Hawker Tempest while on approach. Though still in training, I/JG-1 had scored a number of kills beginning in mid-April, but had also lost thirteen He 162s and ten pilots. Ten of the aircraft losses were the result of various technical malfunctions, such as engine flameouts and sporadic structural failures: just two were shot down. The He 162's 30-minute fuel capacity also caused problems, as at least two of JG-1's pilots were killed attempting emergency landings after exhausting their fuel. In the last days of April, as the Soviet troops approached, II/JG-1 evacuated from Marienhe and on May 2 joined the I/JG-1 at Leck. On May 3, all of JG-1's surviving He 162s were restructured into two groups, I. Einsatz (Combat) and II. Sammel (Replacement). All the JG-1's aircraft where grounded May 5 when General Admiral von Friedeburg signed the surrender of all German armed forces in Holland, Northwest Germany and Denmark. On May 6 when the British reached their airfields, JG-1 turned their He 162s over to the Allies, and examples of the fighter were then shipped to the US, Britain, France, and the USSR for further evaluation. Erprobungskommando 162 fighters, which had been passed on to JV 44, an elite jet unit under Adolf Galland a few weeks earlier, were all destroyed by their crews to keep the jets from falling into Allied hands. By the time of the German unconditional surrender May 8 1945, 120 He 162s had been delivered; a further 200 aircraft had been completed and were awaiting collection or flight-testing; about 600 more were in various stages of production. The difficulties experienced by the He 162 were caused mainly by its rush into production, not by any inherent design flaws. One experienced Luftwaffe pilot who flew it called it a "first-class combat aircraft." Though a RAF pilot was killed in November 1945 when one of the tailfins broke off during the Farnborough air show, a British pilot who evaluated the He 162 praised it.

Variants

Farnborough
- A-0 - designation of the first ten pre-production aircraft.
- A-1 - armed with 2 × 30 mm MK 108 cannons, 50 rounds each.
- A-2 - armed with 2 × 20 mm MG 151/20 cannons, 120 rounds each.
- A-3 - proposed upgrade with reinforced nose mounting twin 30 mm MK 108 cannons.
- A-8 - proposed upgrade with the more powerful Jumo 004D-4 engine.
- B-1 - a proposed follow on planned for 1946, was to include more powerful Heinkel-Hirth 011A turbojet, a stretched fuselage to provide more fuel and endurance as well as increased wingspan, with proper dihedral and discarding the turned-down wingtip extensions. The He 162B-1 was to be armed with twin 30 mm MK 108 cannon.
- He 162B airframe was also used as the basis for possible designs powered by one or two Argus As-044 pulsejet engines.
- C - proposed upgrade featuring the B-series fuselage, Heinkel-Hirth 011A engine, swept wing, a new V shaped tail assembly, and twin MK 108 cannon featuring a Schräge Musik weapons assembly.
- D - proposed upgrade with a configuration similar to C-series but a forward-swept wing.
- E - He 162A fitted with the BMW 003R mixed power plant, a BMW 003A turbojet with an integrated BMW 718 liquid-fuel rocket engine for boost power. At least one prototype was built and flight-tested for a short time.
- S - two-seat training glider.

External links

- [http://www.vectorsite.net/avhe162.html Air Vectors - The Heinkel He 162 Volksjaeger]
- [http://balsi.de/Waffen+Gebaeude/Flugzeuge/he162.htm Heinkel He 162 "Volksjäger"(in German)]
- [http://users.bestweb.net/~kcoyne/he162seat.htm Heinkel 162 Ejection Seat] Category:German fighter aircraft 1940-1949 Category:World_War_II_German_jet_aircraft

Jet engine

is tested at Robins Air Force Base, Georgia, USA. The tunnel behind the engine muffles noise and allows exhaust to escape. The mesh cover at the front of the engine (left of photo) prevents debris—or people—from being pulled into the engine by the huge volume of air rushing into the inlet.]] A jet engine is any engine that accelerates and discharges a fast moving jet of fluid to generate thrust in accordance with Newton's third law of motion. This broad definition of jet engines includes turbojets, turbofans, turboprops, rockets and ramjets, but in common usage, the term generally refers to a gas turbine used to produce a jet of high speed exhaust gases for propulsive purposes.

Turbojet engines

A turbojet engine is a type of internal combustion engine often used to propel aircraft. Air is drawn into the rotating compressor via the intake and is compressed to a higher pressure before entering the combustion chamber. Fuel is mixed with the compressed air and ignited by flame in the eddy of a flame holder. This combustion process significantly raises the temperature of the gas. Hot combustion products leaving the combustor expand through the turbine, where power is extracted to drive the compressor. Although this expansion process reduces both the gas temperature and pressure at exit from the turbine, both parameters are usually still well above ambient conditions. The gas stream exiting the turbine expands to ambient pressure via the propelling nozzle, producing a high velocity jet in the exhaust plume. If the jet velocity exceeds the aircraft flight velocity, there is a net forward thrust upon the airframe. Under normal circumstances, the pumping action of the compressor prevents any backflow, thus facilitating the continuous flow process of the engine. Indeed, the entire process is similar to a four-stroke cycle, but with induction, compression, ignition, expansion and exhaust taking place simultaneously. The efficiency of a jet engine is strongly dependent upon the Overall Pressure Ratio (Combustor Entry Pressure/Intake Delivery Pressure) and the Turbine Inlet Temperature of the cycle. It is also perhaps instructive to compare turbojet engines with propeller engines. Turbojet engines take a relatively small mass of air and accelerate it by a large amount, whereas a propeller takes a large mass of air and accelerates it by a small amount. The high-speed exhaust of a jet engine makes it efficient at high speeds (especially supersonic speeds) and high altitudes. On slower aircraft and those required to fly short stages, a gas turbine-powered propeller engine, commonly known as a turboprop, is more common and much more efficient. Very small aircraft generally use conventional piston engines to drive a propeller but small turboprops are getting smaller as engineering technology improves. The turbojet described above is a single spool design, where a single shaft connects the turbine to the compressor. Higher Overall Pressure Ratio designs often have two concentric shafts, to improve compressor stability during engine throttle movements. The outer (HP) shaft connects the High Pressure (HP) Compressor to the HP turbine. This HP Spool, with the combustor, forms the core or gas generator of the engine. The inner shaft connects the Low Pressure (LP) Compressor to the LP Turbine to create the LP Spool. Both spools are free to operate at their optimum shaft speed.

Turbofan engines

Most modern jet engines are actually turbofans, where the LP Compressor acts as a fan, supplying supercharged air to not only the engine core, but to a bypass duct. The bypass airflow either passes to a separate Cold Nozzle or mixes with LP Turbine exhaust gases, before expanding through a Mixed Flow Nozzle. Forty years ago there was little difference between civil and military jet engines, apart from the use of afterburning in some (supersonic) applications. Turbofans, today, have a low specific thrust (net thrust/airflow) to keep jet noise to a minimum and to improve fuel efficiency. Consequently the bypass ratio (bypass flow/core flow) is relatively high (usually much greater than 3.0). Only a single fan stage is required, because a low specific thrust implies a low fan pressure ratio. Today's military turbofans, however, have a relatively high specific thrust, to maximize the thrust for a given frontal area, jet noise being of little consequence. Multi-stage fans are normally required to achieve the relatively high fan pressure ratio needed for a high specific thrust. Although high Turbine Inlet Temperatures are frequently employed, the bypass ratio tends to be low (usually significantly less than 2.0). An approximate equation for calculating the net thrust of a jet engine is: :F_net = m(v_jfe - v_a ) where: :m = intake mass flow :v_jfe = fully expanded jet velocity (in the exhaust plume) :v_a = aircraft flight velocity While the m·v_jfe term represents the gross thrust of the nozzle, the m·v_a term represents the ram drag of the intake. Most types of jet engine have an air intake, which provides the bulk of the gas exiting the exhaust. There is, however, a penalty for picking this air up and this is known as the ram drag. Conventional rocket motors, however, do not have an air intake, the oxidizer being carried within the airframe. Consequently, rocket motors do not have ram drag; the gross thrust of the nozzle is the net thrust of the engine. Consequently, the thrust characteristics of a rocket motor are completely different from that of an air breathing jet engine; at full throttle, the thrust of a rocket motor improves slightly with increasing altitude (because the back pressure from the atmosphere falls), whereas with a turbojet (or turbofan) the falling density of the air entering the intake causes the net thrust to decrease with increasing altitude.

History

Before the advent of the jet engine, the reciprocating piston engine in its different forms (rotary and static radial, aircooled and liquid-cooled inline) had been the only type of powerplant available to aircraft designers. This was understandable so long as low aircraft performance parameters were considered acceptable, and indeed inevitable. However, by approximately the late 1930s, engineers were beginning to realize that conceptually the piston engine was self-limiting in terms of the maximum performance which could be obtained from it; the limit was essentially one of propeller efficiency, which seemed to peak as blade tips approached supersonic tangential velocity. 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 conceived. The latter would prove to be the case. The gas turbine (turbojet, or simply jet) engine, as subsequently developed, would become almost as revolutionary to aviation as the Wright brothers' first flight. 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, although Colin Sullivan of Cowplain, England was said to have drawn up identical blueprints 2 years beforehand. The earliest attempts at jet engines were hybrid designs in which an external power source supplied the compression. In this system (called a thermojet by Secondo Campini) the air is first compressed by a fan driven by a conventional piston engine, then it is mixed with fuel and burned for jet thrust. The examples of this type of design were the Henri Coanda's Coanda-1910 aircraft, and the much later Campini Caproni CC.2, 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. World War II The key to the useful jet engine was the gas turbine, used to extract energy to drive the compressor from the engine itself. The first gas turbine to successfully run self-sustaining was built in 1903 by Norwegian engineer Aegidius Elling. The first patents for jet propulsion were issued in 1917. Limitations in design and practical engineering and metallurgy prevented such engines reaching manufacture. The main problems were safety, reliability, weight and, especially, sustained operation. On January 16, 1930, in England Frank Whittle submitted patents for his own design for a full-scale aircraft engine (granted in 1932). In 1935 Hans von Ohain started work on a similar design in Germany, seemingly unaware of Whittle's work. Ohain approached 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 engine running by September 1937. Unlike Whittle's design, Ohain used hydrogen as fuel, which he credits for the early success. 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 Marienehe aerodrome, an impressively short time for development. The He 178 was the world's first jetplane. The engine was starting to look useful, and Whittle's 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, and first flew on May 15, 1941 at RAF Cranwell. RAF Cranwell One problem with both of these early designs, which are called centrifugal-flow engines, was that the compressor works by "throwing" (accelerating) air outward from the central intake to the outer periphery of the engine where the air is then compressed by a divergent duct setup—converting velocity into pressure. The advantage was that such compressor designs were well understood in centrifugal superchargers but this leads to a very large cross section for the engine at rotational speeds that were usable at the time. A disadvantage was that the air flow had to be "bent" to flow rearwards through the combustion section and to the turbine and tailpipe. With improvements to bearings, the shaft speed of the engine would increase and the diameter of the centrifugal compressor would reduce greatly. The shortness of this engine is an advantage. The strength of this type of compressor is an advantage over the later axial-flow compressors that are still liable to foreign object damage (FOD in aviation parlance). Austrian Anselm Franz of Junkers' engine division (Junkers Motoren or Jumo) addressed this problem 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 to 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. Jumo was assigned the next engine number, 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. Because Hitler wanted a new bomber the Me 262 came too late to decisively impact Germany's position in World War II, but it will be remembered as the first use of jet engines in service. After the end of the war the German Me 262 aircraft were extensively studied by the victorious allies and contributed to work on early Soviet and US jet fighters. British engines also were licensed widely in the US (see Tizard Mission). Their most famous design, the Nene would also power the USSR's jet aircraft also after a technology exchange. American designs would not come fully into their own until the 1960s.

Types

There are a large number of types of jet engines, which get propulsion from a high speed exhaust jet. Some examples are as follows:

Type	Description	Advantages	Disadvantages
Water jet	Squirts water out the back of a boat	Can run in shallow water, powerful, less harmful to wildlife	Can be less efficient than a propeller, more vulnerable to debris
Thermojet	Most primitive airbreathing jet engine		Very inefficient and underpowered
Turbojet	Generic term for simple turbine engine	Simplicity of design	Basic design, misses many improvements in efficiency and power
Turbofan	Power tapped off exhaust used to drive bypass fan	Quieter due to greater mass flow and lower total exhaust speed, more efficient for a useful range of subsonic airspeeds for same reason	Greater complexity (additional ducting, usually multiple shafts), large diameter engine, need to contain heavy blades. More subject to FOD and ice damage. Different degrees of bypass are possible - this is the design most commonly used on commercial airliners
Rocket	Carries own propellant onboard, emits jet for propulsion	Very few moving parts, Mach 0 to Mach 25+, efficient at very high speed (> Mach 10.0 or so), thrust/weight ratio over 100, relatively simple, no air inlet, doesn't require atmosphere, high compression ratio, very high speed exhaust	very low specific impulse- typically 100-450 seconds. Typically requires carrying oxidiser onboard which increases risks.
Ramjet	Intake air is compressed entirely by speed of oncoming air and duct shape (divergent)	Very few moving parts, Mach 0.8 to Mach 5+, efficient at high speed (> Mach 2.0 or so), lightest of all airbreathing jets (thrust/weight ratio up to 30 at optimum speed)	Must have a high initial speed to function, inherently inefficient at slow speeds due to poor compression ratio, difficult to arrange shaft power for accessories, difficult to engineer to be efficient over a wide range of airspeeds.
Turboprop (Turboshaft similar)	Strictly not a jet at all- a gas turbine engine is used as powerplant to drive (propeller) shaft	High efficiency at lower subsonic airspeeds(300 knots plus), high shaft power to weight	Limited top speed (aeroplanes), somewhat noisy, complexity of propeller drive, very large yaw (aeroplane) if engine fails
Propfan	Turboprop engine drives one or more propellers. much like a turbofan but without ductwork	Higher fuel efficiency, some designs are less noisy than turbofans, could lead to higher-speed commercial aircraft, popular in the 1980s during fuel shortages,	Development of propfan engines has been very limited, typically more noisy than turbofans, complexity
Pulsejet	Air enters a divergent-duct inlet, the front of the combustion area is shut, fuel injected into the air ignites, exhaust vents from other end of engine	Very simple design, commonly used on model aircraft	Noisy, inefficient (low compression ratio), works best at small scale, valves need to be replaced very often
Pulse detonation engine	Similar to a pulsejet, but combustion occurs as a detonation instead of a deflagration, may or may not need valves	Maximum theoretical engine efficiency	Extremely noisy, parts subject to extreme mechanical fatigue, hard to start detonation, not practical for current use
Integral rocket ramjet	Essentially a ramjet where intake air is compressed and burnt with the exhaust from a rocket	Mach 0 to Mach 4.5+ (can also run exoatmospheric), good efficiency at Mach 2 to 4	Similar efficiency to rockets at low speed or exoatmospheric, inlet difficulties, a relatively undeveloped and unexplored type, cooling difficulties
Scramjet	Intake air is compressed but not slowed to below supersonic, intake, combustion and exhaust occur in a single constricted tube	can operate at very high Mach numbers (Mach 8 to 15)[http://www.dod.mil/ddre/downloads/ddre_briefings/Merging_Air_and_Space071603.pdf]	still in development stages, must have a very high initial speed to function (Mach >6), cooling difficulties, inlet difficulties, very poor thrust/weight ratio (~2), airframe difficulties, testing difficulties
Turborocket	An additional oxidizer such as oxygen is added to the airstream to increase max altitude	Very close to existing designs, operates in very high altitude, wide range of altitude and airspeed	Airspeed limited to same range as turbojet engine, carrying oxidizer like LOX can be dangerous
Precooled jets / LACE	Intake air is chilled to very low temperatures at inlet	Very high thrust/weight ratios are possible (~14) together with good fuel efficiency over a wide range of airspeeds, mach 0-5+	Exists only at the lab protoyping stage. Examples include RB545, SABRE, ATREX

Components

The components of a jet engine are standard across the different types of engines, although not all engine types have all components. The parts include:

Air Induction
The standard reference frame for a jet engine is the aircraft itself. For subsonic aircraft, the air intake to a jet engine presents no special difficulties, and consists essentially of an opening which is designed to minimise drag, as with any other aircraft component. However, the air reaching the compressor of a normal jet engine must be travelling below the speed of sound, even for supersonic aircraft, to sustain the flow mechanics of the compressor and turbine blades. At supersonic flight speeds, shockwaves form in the intake system and reduce the recovered pressure at inlet to the compressor. So some supersonic intakes use devices, such as a cone or ramp, to increase pressure recovery, by more making more efficient use of the shock wave system.
Compressor or Fan
In many cases, the compressor is a series of fans that are spaced very closely together. Each fan compresses the air a little more. Energy is derived from the turbine (see below), passed along the shaft.
Shaft
This carries power from the turbine to the compressor, and runs most of the length of the engine. There may be as many as three concentric shafts, rotating at independent speeds, with as many sets of turbines and compressors. Other services, like a bleed of cool air, may also run down the shaft.
Combustor or Can or Flameholders or Combustion Chamber
This is a chamber where fuel is continuously burned in the compressed air.
Turbine
The turbine acts like a windmill, extracting energy from the hot gases leaving the combustor. This energy is used to drive the compressor through the shaft, or bypass fans, or props, or even (for a gas turbine-powered helicopter) converted entirely to rotational energy for use elsewhere.
Afterburner or reheat (chiefly UK)
(mainly military) Produces extra thrust by burning extra fuel, usually inefficiently, to significantly raise Nozzle Entry Temperature at the exhaust. Owing to a larger volume flow (i.e. lower density) at exit from the afterburner, an increased nozzle flow area is required, to maintain satisfactory engine matching, when the afterburner is alight.
Exhaust or Nozzle
Hot gases leaving the engine exhaust to atmospheric pressure via a nozzle, the objective being to produce a high velocity jet. In most cases, the nozzle is convergent and of fixed flow area.
Supersonic Nozzle
If the Nozzle Pressure Ratio (Nozzle Entry Pressure/Ambient Pressure) is very high, to maximize thrust it may be worthwhile, despite the additional weight, to fit a convergent-divergent (de Laval) nozzle. As the name suggests, initially this type of nozzle is convergent, but beyond the throat (smallest flow area), the flow area starts to increase to form the divergent portion. The expansion to atmospheric pressure and supersonic gas velocity continues downstream of the throat, whereas in a convergent nozzle the expansion beyond sonic velocity occurs externally, in the exhaust plume. The former process is more efficient.

Design considerations

The various components named above have constraints on how they are put together to generate the most efficiency or performance. Important here is air intake design, overall size, number of compressor stages (sets of blades), fuel type, number of exhaust stages, metallurgy of components, amount of bypass air used, where the bypass air is introduced, and many other factors. For instance, let us consider design of the air intake.

Air intakes

See also: Inlet cone
Subsonic inlets
At low speeds a subsonic inlet is little more than a hole, with an aerodynamic fairing around it. However, from around mach 0.85, the air entering the inlet can start to experience shock waves, and then careful radiusing is required for optimum performance at all speeds.
Supersonic inlets
Inlet cone For aircraft travelling at supersonic speeds, a design complexity arises, since the air ingested by the engine must be below supersonic speed, otherwise the engine will "choke" and cease working. This subsonic air speed is achieved by passing the approaching air through a deliberately generated shock wave (since one characteristic of a shock wave is that the air flowing through it is slowed). Therefore, some means is needed to create a shockwave ahead of the intake. The earliest types of supersonic aircraft featured a central shock cone, called an inlet cone, which was used to form the shock wave. This type of shock cone is clearly seen on the English Electric Lightning and MiG-21 aircraft, for example. The same approach can be used for air intakes mounted at the side of the fuselage, where a half cone serves the same purpose with a semicircular air intake, as seen on the F-104 Starfighter and BAC TSR-2. A more sophisticated approach is to angle the intake so that one of its edges forms a leading blade. A shockwave will form at this blade, and the air ingested by the engine will be behind the shockwave and hence subsonic. The Century series of US jets featured a number of variations on this approach, usually with the leading blade at the outer vertical edge of the intake which was then angled back inwards towards the fuselage. Typical examples include the Republic F-105 Thunderchief and F-4 Phantom. Later this evolved so that the leading edge was at the top horizontal edge rather than the outer vertical edge, with a pronounced angle downwards and rearwards. This approach simplified the construction of the intakes and permitted the use of variable ramps to control the airflow into the engine. Most designs since the early 1960s now feature this style of intake, for example the F-14 Tomcat, Panavia Tornado and the Concorde.
SR 71
The SR-71's engines were rather unusual in that a variable air intake design was used to convert the engine from a turbojet to a ramjet, in flight. To get good efficiency over a wide range of speeds the Pratt & Whitney J58 could move a conical spike fore and aft within the engine nacelle, to keep the supersonic shock wave just in front of the inlet. In this manner, the airflow behind the shock wave, and more importantly, through the engine, was kept subsonic at all times. At high mach, the compressor for the J58 was unable to carry the high air flow entering the inlet without stalling its blades, and so the engine directed the excess air through 6 bypass pipes straight to the afterburner. At high speeds the engine actually obtained 80% of its thrust, versus 20% through the turbines itself, in this way. Essentially, this allowed the engine to operate as a ramjet, actually improving specific impulse (fuel efficiency) by 10%–15%.
Heat exchangers
For engines that may need to operate at almost hypersonic speeds (mach 0 to 6), there is strong theoretical and experimental support for using a heat-exchanger to cool the air at the intake. This can increase the density of the air and thus reduce the necessary compression. The lower temperatures also permit lighter alloys to be used hence reducing the engine's weight by several times. This leads to plausible designs like SABRE and ATREX that might permit jet engined vehicles to be used to launch to space. ATREX
Compressors
Each design of compressor has an operating map or characteristic peculiar to that unit. At a given throttle condition, the compressor operates somewhere along the steady state running line. Unfortunately, this operating line is displaced during transients and under extreme conditions can cross the surge or stall line (see compressor map), causing, in some cases, the compressor flow to reverse direction violently. Many compressors are fitted with variable geometry to decrease the likelihood of surge. Another ploy is to split the compressor into two or more units, operating on separate concentric shafts. Another design consideration is the average stage loading. This can be kept at a sensible level either by increasing the number of compression stages (more weight/cost) or the mean blade speed (more blade/disc stress). Although large flow compressors are usually all-axial, the rear stages on smaller units are too small to be robust. Consequently, these stages are often replaced by a single centrifugal unit. Very small flow compressors often employ two centrifugal compressors, connected in series. Although in isolation centrifugal compessors are capable of running at quite high pressure ratios (e.g. 10:1), impeller stress considerations (i.e. T3, NH implications) limit the CF pressure ratio that can be employed in high overall pressure ratio engine cycles. Increasing overall pressure ratio implies a higher (HP) compressor exit temperature (i.e. T3. This implies a higher HP shaft speed, to maintain the datum blade tip Mach number on the rear compressor stages. Stress considerations, however, may limit shaft speed increases, leading to a reduction in the pressure ratio of the rear stages. compressor map
Combustors
Care must be taken to keep the flame burning in a moderately fast moving airstream, at all throttle conditions, as efficiently as possible. Since the turbine cannot withstand stoichiometric temperatures, resulting from the optimum combustion process, some of the compressor air is used to quench the exit temperature of the combustor to an acceptable level.
Turbines
stoichiometric Because a turbine expands from high to low pressure, there is no such thing as turbine surge or stall. Designers must, however, prevent the turbine blades and vanes from melting in a very high temperature and stress environment. Consequently bleed air extracted from the compression system is often used to cool the turbine blades/vanes internally. Other solutions are improved materials and/or special insulating coatings. The discs must be specially shaped to withstand the huge stresses imposed by the rotating blades. Improved materials help to keep disc weight down.
Nozzles
stresses Most jet engines use a simple convergent nozzle, which is relatively easy to design. However, afterburning engines require a variable area nozzle, to maintain sensible engine matching when the afterburner is alight. This is usually accommodated by using a series of interlocking petals (driven by pneumatic or hydraulic rams) to adjust the throat area. Even more complexity is introduced if a convergent-divergent nozzle is fitted, especially if the throat and exit areas are adjusted independently. convergent-divergent nozzle Rocket motors also employ convergent-divergent nozzles, but these are usually of fixed geometry, to minimize weight. Because of the much higher nozzle pressure ratios experienced, rocket motor con-di nozzles have a much greater area ratio (exit/throat) than those fitted to jet engines. At the other extreme, some high bypass ratio civil turbofans use an extremely low area ratio (less than 1.01 area ratio), convergent-divergent, nozzle on the bypass (or mixed exhaust) stream, to control the fan working line. The nozzle acts as if it has variable geometry. At low flight speeds the nozzle is unchoked (less than a Mach number of unity), so the exhaust gas speeds up as it approaches the throat and then slows down slightly as it reaches the divergent section. Consequently, the nozzle exit area controls the fan match and, being larger than the throat, pulls the fan working line slightly away from surge. At higher flight speeds, the ram rise in the intake increases nozzle pressure ratio to the point where the throat becomes choked (M=1.0). Under these circumstances, the throat area dictates the fan match and being smaller than the exit pushes the fan working line slightly towards surge. This is not a problem, since fan surge margin is much better at high flight speeds.
Engine Performance

TS Diagram
Mach number °R) = 1 Btu/(lb °F) = 1 kcal/(kg °C) = 4.184 kJ/(kg·K).]] Temperature vs. entropy diagrams (see example, above) are usually used to illustrate the cycle of gas turbine engines. All the reader really needs to know about entropy is that it represents the degree of disorder of the molecules in the fluid and that it tends to increase! Apart from stations 0 and 8s, stagnation pressure and stagnation temperature are used. Station 0 is ambient. The processes depicted are: ;Freestream (stations 0 to 1) :In the example, the aircraft is stationary, so stations 0 and 1 are coincident. Station 1 is not depicted on the diagram. ;Intake (stations 1 to 2) :In the example, a 100% intake pressure recovery is assumed, so stations 1 and 2 are coincident. ;Compression (stations 2 to 3) :The ideal process would appear vertical on a TS diagram. In the real process there is friction, turbulence and, possibly, shock losses, making the exit temperature, for a given pressure ratio, higher than ideal. The shallower the positive slope on the TS diagram, the less efficient the compression process. ;Combustion (stations 3 to 4) :Heat (usually by burning fuel) is added, raising the temperature of the fluid. There is an associated pressure loss, some of which is unavoidable ;Turbine (stations 4 to 5) :The temperature rise in the compressor dictates that there will be an associated temperature drop across the turbine. Ideally the process would be vertical on a TS diagram. However, in the real process, friction and turbulence cause the pressure drop to be greater than ideal. The shallower the negative slope on the TS diagram, the less efficient the expansion process. ;Jetpipe (stations 5 to 8) :In the example the jetpipe is very short, so there is no pressure loss. Consequently, stations 5 and 8 are coincident on the TS diagram. ;Nozzle (stations 8 to 8s) :These two stations are both at the throat of the (convergent) nozzle. Station 8s represents static conditions. Not shown on the TS diagram is the expansion process, external to the nozzle, down to ambient pressure.
Design Point Performance Equations
In theory, any combination of flight condition/throttle setting can be nominated as the engine performance Design Point. Usually, however, the Design Point corresponds to the highest corrected flow at inlet to the compression system (e.g. Take-off Rating, Sea Level Static, ISA) The design point net thrust of any jet engine can be estimated by working through the engine cycle, step by step. Below are the equations for a single spool turbojet. Freestream
$T_1 = t_0 \cdot (1 + (_c-1)\cdot M^2/2)$ $P_1 = p_0 \cdot (T_1/t_0)^$ Intake
$T_2=T_1 \,$ $P_2=P_1 \cdot \mathrm$ Compressor
$T_3 = T_2 \cdot ((P_3/P_2) ^$ $P_3 = P_2 \cdot (P_3/P_2)$ Combustor
$T_4 = \mathrm \,$ $P_4 = P_3 \cdot (P_4/P_3)$ Turbine
Equating the turbine and compressor powers, we have:
$w_4 \cdot C_(T_4-T_5) = w_2 \cdot C_(T_3-T_2)$ A simplyfying assumption sometimes made is for the addition of fuel flow to be exactly offset by an overboard compressor bleed, so mass flow remains constant throughout the cycle. $P4/P5 = (T4/T5)^$ Jetpipe
$T_8 = T_5 \,$ $P_8 = P_5 (P_8/P_5) \,$ Nozzle
$t_ = T_8/((_t+1)/2) \,$ $p_ = P_8/((T_8/t_)^)$ $V_8^2 = 2gJC_(T_8 - t_)$ $_ = p_/(R \cdot t_)$ $A_8 = w_8/(_ \cdot V_8)$ Gross Thrust
$F_g = C_\mathrm((w_8 \cdot V_8/g) + A_8(p_ - p_0))$ Ram Drag
$F_r = w_0 \cdot V_0/g$ Net Thrust
$F_n = F_g - F_r \,$ Note that mass flow is the sizing parameter: doubling the airflow, doubles the thrust. Note:
- A flow area
- C_pc specific heat at constant pressure for air
- C_pt specific heat at constant pressure for combustion products
- C_x thrust coefficient
- g acceleration of gravity
- J mechanical equivalent of heat
- M flight Mach number
- p static pressure
- P total pressure
- prf intake pressure recovery factor
- R gas constant
- RIT (turbine) rotor inlet temperature
- t static temperature
- T total temperature
- V velocity
- w mass flow
- ρ density
- γ_c ratio of specific heats for air
- γ_t ratio of specific heats for combustion products
- η_pc compressor polytropic efficiency
- η_pt turbine polytropic efficiency
Off-design
An engine is said to be running off-design if any of the following apply: :a) change of throttle setting :b) change of altitude :c) change of flight speed :d) change of climate :e) change of installation (e.g. customer bleed or power off-take) Although each off-design point is effectively a design point calculation, the resulting cycle (normally) has the same turbine and nozzle geometry as that at the engine design point. Obviously the final nozzle cannot be over or underfilled with flow. This rule also applies to the turbine nozzle guide vanes, which act like small nozzles. Design point calculations are normally done by a computer program. By the addition of an iterative loop, such a program can also be used to create a crude off-design model. The variables for the single spool turbojet iteration would typically be: RIT (or some other function of fuel flow), w₂,P₃/P₂ Typically, the constraints imposed would be: Engine match (e.g. F_n , fuel flow, etc), A_{8 geometric},w4cor The latter two are the physical constraints that must be met. Corrected flow is the flow that would pass through a device, if the entry pressure and temperature corresponded to ambient conditions at sea level on a Standard Day. A more refined off-design model can be created using compressor maps and turbine maps to predict off-design efficiencies, relative shaft speeds, etc. The nominal net thrust quoted for a jet engine usually refers to the Sea Level Static (SLS) condition, either for the International Standard Atmosphere (ISA) or a hot day condition (e.g. ISA+10 °C). As an example, the GE90-76B has a take-off static thrust of 76,000 lbf (360 kN) at SLS, ISA+15 °C. Naturally, net thrust will decrease with altitude, because of the lower density. There is also, however, a flight speed effect. Initially as the aircraft gains speed down the runway, there will be little increase in nozzle pressure and temperature, because the ram rise in the intake is very small. There will also be little change in mass flow. Consequently, nozzle gross thrust initially only increases marginally with flight speed. However, being an air breathing engine (unlike a conventional rocket) there is a penalty for taking on-board air from the atmosphere. This is known as ram drag. Although the penalty is zero at static conditions, it rapidly increases with flight speed causing the net thrust to be eroded. As flight speed builds up after take-off, the ram rise in the intake starts to have a significant effect upon nozzle pressure/temperature and intake airflow, causing nozzle gross thrust to climb more rapidly. This term now starts to offset the still increasing ram drag, eventually causing net thrust to start to increase. In some engines, the net thrust at say Mach 1.0, sea level can even be slightly greater than the static thrust. Above Mach 1.0, with a subsonic inlet design, shock losses tend to decrease net thrust, however a suitably designed supersonic inlet can give a subsonic airspeed entering the compressor, while giving a useful compression, and thus net thrust and efficiency can continue to climb. The thrust lapse described above depends on the design specific thrust and, to a certain extent, on how the engine is rated with intake temperature.
Rated Performance

Civil
turbine map Nowadays, civil engines are usually flat-rated on net thrust up to a 'break-point' climate. So at a given flight condition, net thrust is held approximately constant over a very wide range of ambient temperature, by increasing (HP) turbine rotor inlet temperature (RIT or SOT). However, beyond the break-point, SOT is held constant and net thrust starts to fall for further increases in ambient temperature. Consequently, aircraft fuel load and/or payload must be decreased. Usually, for a given rating, the kink-point SOT is held constant, regardless of altitude or flight speed. Some engines have a special rating, known as the 'Denver Bump'. This invokes a higher RIT than normal, to enable fully laden aircraft to Take-off safely from Denver, CO in the summer months. Denver Airport is extremely hot in the summer and the runways are over a mile above sea level. Both of these factors affect engine thrust.
Military
turbine map The rating systems used on military engines vary from engine to engine. A typical military rating structure is shown on the left. At low intake temperatures, the engine tends to operate at maximum corrected speed or corrected flow. As intake temperature rises, a limit on (HP) turbine rotor inlet temperature (SOT) takes effect, progressively reducing corrected flow. At even higher intake temperatures, a limit on compressor delivery temperature (T₃) is invoked, which decreases both SOT and corrected flow. corrected flow The impact of design intake temperature is shown on the right hand side. An engine with a low design T₁ combines high corrected flow with high rotor turbine temperature (SOT), maximizing net thrust at low T₁ conditions (e.g. Mach 0.9, 30000 ft, ISA). However, although turbine rotor inlet temperature stays constant as T₁ increases, there is a steady decrease in corrected flow, resulting in poor net thrust at high T₁ conditions (e.g. Mach 0.9, sea level, ISA). Although an engine with a high design T₁ has a high corrected flow at low T₁ conditions, the SOT is low, resulting in a poor net thrust. Only at high T₁ conditions is there the combination of a high corrected flow and a high SOT, to give good thrust characteristics. A compromise between these two extremes would be to design for a medium intake temperature (say 290 K).
See also

- Jet aircraft
- Jetboat
- Spacecraft propulsion
- Supercharger
- Turbocharger
- Gas turbine
- Kurt Schreckling who built practical jet engines for model aircraft
- Wikibooks: Jet propulsion
External link

- [http://www.rmcybernetics.com/projects/DIY_Devices/homemade_jet_engine.htm RMCybernetics - A simple Homemade Jet Engine]
- [http://www.rolls-royce.com/education/schools/journey02/flash.html Journey through a jet engine(flash)]
- [http://travel.howstuffworks.com/turbine.htm How Stuff Works article on how a Gas Turbine Engine works]
- [http://www.generalatomic.com/jetmakers/chapter15.html Influence of the Jet Engine on the Aerospace Industry]
- [http://www.rand.org/publications/MR/MR1596/MR1596.appb.pdf An Overview of Military Jet Engine History] (Rand Corp., 24 pgs, PDF)
- [http://bikerodnkustom3.homestead.com/danger.html A jet propulsion bicycle] Category:Energy conversion Category:Gas turbines Category:Jet engines ja:ジェットエンジン

Luftwaffe

right The (German: "air force", IPA: ['luftvafə]) is the commonly used term for the German air force. The history of the Luftwaffe began in 1910 with the founding of the Imperial German Army Air Service (Luftstreitkräfte), yet it has not been continuous because Germany lost both World Wars (1914-1918 and 1939-1945). As a result, the Germans had no military air force between 1918 and 1935 and again between 1945 and 1955. For many English speakers, the term "Luftwaffe" is synonymous with the air force of Nazi Germany. In 1939-1940, this Luftwaffe helped the German army to astonishingly rapid success in both Eastern and Western Europe, but which failed to win control of the skies over England. Later on, despite its best efforts, it could not prevent the defeat of the Third Reich either by day, or by night, owing to constant Allied bombing of Germany's factories and cities by a numerically overwhelming force of bombers based in England. This was coupled with the advances of the Soviet armies from the East, as numbers of available German aircraft dwindled in the face of ever-growing numbers of Soviet aircraft. The Luftwaffe was, however, notable in putting the world's first jet fighter and the world's only rocket-powered fighter into action during the war. Between 1955 and 1990, there were two German air forces as a result of the splitting of the defeated Germany in 1945 into two, but the air force of the GDR was dissolved and its structure taken over by the Luftwaffe in 1990 upon the German reunification. Only in Bosnia in 1999 has the Luftwaffe ever seen war action since the end of World War II.

History

World War I

World War II The forerunner of the Luftwaffe, the Imperial German Army Air Service—the Luftstreitkräfte ("Air-fighting Forces"), was founded in 1910 before the outbreak of World War I (1914–1918) with the emergence of military aircraft, although they were intended to be used primarily for reconnaissance in support of armies on the ground, just as balloons had been used in the same fashion during the Franco-Prussian War of 1870–1871 and even as far back as the Napoleonic Wars. It was not the world's first air force, however, because France's embryonic army air service, which eventually became the L'Armée de l'Air, had also been founded in 1910, and Britain's Royal Flying Corps,( which merged in 1918 with the Royal Naval Air Service to form the Royal Air Force), was founded in 1912. During the war, the Imperial Army Air Service utilised a wide variety of aircraft, ranging from fighters (such as those manufactured by Albatros-Flugzeugwerke and Fokker), reconnaissance aircraft (Aviatik and DFW) and heavy bombers (Gothaer Waggonfabrik, better known simply as Gotha, and Zeppelin-Staaken). Gothaer Waggonfabrik However, the fighters received the most attention in the annals of military aviation, since it produced "aces" such as Manfred von Richthofen, popularly known as "The Red Baron", Ernst Udet, Hermann Göring, Oswald Boelcke (considered the first master tactician of "dogfighting"), Max Immelmann (the first airman to win the Pour le Mérite, Imperial Germany's highest decoration for gallantry, as a result of which the decoration became popularly known as the "Blue Max"), and Werner Voss. As well as the German Navy, the German Army also used Zeppelins as airships for bombing military and civilian targets in occupied France and Belgium as well as the United Kingdom. All aircraft in service until early 1918 were distinguishable as being German from the Iron Cross that was being used as the German military aircraft insignia. (It should be noted, though, that Germany's closest ally, Austria-Hungary, also adopted the Iron Cross for its aircraft.) Iron Cross and so became one of the best-known fighter planes of World War I.]] From early 1918, German military aircraft began to sport the straight-line Balken Cross (Balkenkreuz, Balken = beam), which would become better known the world over during the era of the Third Reich. After the war ended in German defeat, the service was dissolved completely under the conditions of the Treaty of Versailles, which demanded that its aeroplanes be completely destroyed. As a result of this disbanding, the present-day Luftwaffe (which dates from 1955, in any case) is not the oldest independent air force in the world, since the Royal Air Force of the United Kingdom is older, having been founded on 1 April 1918.

Inter-war period

Since Germany had been banned by the Treaty of Versailles from having an air force, there existed the need to train its pilots for a future war in secret. Initially, civil aviation schools within Germany were used, yet only light training planes could be used in order to maintain the facade that the trainees were going to fly with civil airlines such as Lufthansa. In order to train its pilots on the latest combat aircraft, Germany solicited the help of its future enemy, the USSR. A secret training airfield was established at Lipetsk in 1924 and operated for approximately nine years using mostly Dutch and Russian, but also some German, training aircraft before being closed in 1933. USSR On February 26, 1935, Adolf Hitler ordered Hermann Göring to reinstate the Luftwaffe, breaking the Treaty of Versailles signed in 1919. Germany broke it without sanction from Britain and France or the League of Nations, yet neither the two nations nor the League did anything to oppose either this or any other action which broke the provisions of the Treaty. Although the new air force was to be run totally separately from the army, it retained the tradition of according army ranks to its officers and airmen, a tradition retained today by the Bundesluftwaffe of the unified Germany and by many air forces throughout the world. However, it is worth noting that, before the official promulgation of the Luftwaffe, what was a paramilitary air force was known as the Deutscher Luftverband ("German Air Union"; DLV for short), with Ernst Udet as its head, and the DLV uniform insignia became those of the new Luftwaffe, although the DLV "ranks" were actually given special names that made them sound more civilian than military. It is of interest to note that Dr. Fritz Todt, the engineer who founded the Organisation Todt that organised the construction of roads before the war and of fortifications, such as the so-called "Atlantic Wall", using thousands of forced labourers during World War II, was appointed to the rank of Generalmajor in the Luftwaffe even if he was not, strictly speaking, an airman, although he had served in an observation squadron during World War I, winning the Iron Cross. (Ironically, he died in an air crash in February 1942.) The Luftwaffe had the ideal opportunity to test its pilots, aircraft and tactics in the Spanish Civil War of 1936–1939, when the Condor Legion was sent to Spain in support of the anti-Republican government revolt led by Francisco Franco. Modern machines included names which would become world famous: the Junkers Ju 87 Stuka dive-bomber and the Messerschmitt Bf 109 fighter plane. However, as aircraft seconded to Franco's Nationalist air force, Luftwaffe markings were replaced so as not to make the world believe that Germany was actively supporting the revolt. Instead of the Nazi Party's swastika on the tailplane, the German planes used the Nationalist air force aircraft markings (a Saint Andrew's cross over a white background, painted on the rudder of the aircraft and, on the fuselage and wings, meanwhile, instead of the Balkankreuz, there was a black disc. All aircraft in the Legion were affiliated to units given a designation ending in the number 88. For example, bombers were in Kampfgruppe ("Battle Group") 88, abbreviated to K/88, and fighters in Jagdgruppe ("Hunt Group") 88, J/88. swastika A grim foretaste of the systematic bombing of cities during World War II came in April 1937 when a combined force of German and Italian bombers under National Spanish command destroyed most of the Basque city of Guernica in north-east Spain. This bombing received worldwide condemnation, and the collective memory of the horror of the bombing of civilians has ever since become most acute via the famous painting, named after the town, by the Cubist artist, Pablo Picasso. Many feared that this would be the way that future air wars would be conducted, since the Italian strategist, General Giulio Douhet (who had died in 1930), had formulated theories regarding what would be dubbed "strategic bombing", the idea that wars would be won by striking from the air at the heart of the industrial muscle of a warring nation, and thus demoralising the civilian population to the point where the government of that nation would be driven to sue for peace—a portent of things to come, certainly, and not just during the war which would break out in Europe only months after the end of the civil war in Spain.

World War II

Giulio Douhet By the summer of 1939, on the eve of the outbreak of World War II, the Luftwaffe had become the most powerful air force in the world. As such it played a major role in Germany's early successes in the war and formed a key part of the Blitzkrieg concept, much due to the use of the innovative Junkers Ju 87 dive bomber (Sturzkampfflugzeug—Stuka). Germany swept through Poland, Norway, Denmark, Luxembourg, Belgium, The Netherlands and France in a matter of months between September 1939 and June 1940 due in no small part to the Luftwaffe, which seemed invincible, causing Göring to become over-confident in its abilities and boasting that the RAF would be defeated in a matter of a month before the planned launch of Operation Sealion (Seelöwe), the invasion of the United Kingdom. Faulty German intelligence and poor leadership did as much to save Fighter Command as Dowding's careful husbanding of his precious pilots; Hitler's decision to shift the focus of operations to bombing industrial targets in cities instead of British airfields was crucial mistake. When Churchill praised "the few" for their victory in his famous speech, he omitted the Germans, who deserved at least some of the credit. German air power was preserved in the succeeding period as much by RAF Bomber Command's faulty strategy as by German tenacity. Advanced by Sir Charles Portal, accepted by Churchill, & ruthlessly executed by Sir Arthur Harris, it produced a calamity with overtones of Haig in World War One, throwing men and machines against increasingly strong defenses, with little to show for it. The postulated "breaking" of German morale was a dim sight on the horizon, with no carefully articulated plan to achieve it. The entry of the United States into the conflict in December 1941 drew American bomber forces into the same futile project. Unlike the Germans, the U.S. Army Air Forces (USAAF), under the command of General Henry H. Arnold, developed a strategic bomber force. The USAAF bombers penetrated deep into Reich territory and maintained daylight bombing of industrial targets, without fighter escort (which had been demonstrated as necessary even against derisively weak Chinese fighter attacks), while their RAF colleagues (who had learned better) continued with the offensive by conducting night operations. Nevertheless, the Luftwaffe remained strong, and both the day fighters and the night fighters (see below) were able to shoot down hundreds of Allied bombers, including 95 on a single night (October 30–31, 1944) when the RAF bombed the southern city of Nuremberg, famous as the place where pre-war Nazi Party rallies took place (and, post-war, where the trials of Nazi criminals, including Göring, would take place). Henry H. Arnold German superiority was especially felt on the Eastern Front, given that the Luftwaffe enjoyed an advanced technical standard as well as employing highly trained and experienced pilots such as Hans-Ulrich Rudel, who, flying the Stuka, was to become the most highly decorated pilot of the war, winning the Knight's Cross with Golden Oakleaves, Swords and Diamonds (Das Ritterkreuz mit Goldenem Eichenlaub, Schwertern und Brillanten) by the end of 1944 and being promoted to Oberst (Colonel). Unlike other officers of such high rank, Oberst Rudel would remain in the front line until his surrender as Kommodore of SG 2 (a combined dive-bomber and fighter unit) to the U.S. Army at Kitzingen in Czechoslovakia on V-E Day, May 8, 1945. Amongst the Experten (the name given to German aces), Erich Hartmann would emerge at the end of the war with the highest number of enemy aircraft shot down—352, a total initially disputed but eventually accepted. In contrast, the highest number of aircraft shot down by any Allied pilot was 62, achieved by Colonel (later Colonel-General) Ivan Kozhedub of the Soviet Army Air Force. Nevertheless, the vast land mass of Russia allowed the Soviets to manufacture war matériel well away from the front line, and so it was partly due to overwhelming numbers of weapons made available to the ground and air forces of the USSR that the Soviets managed to push the Germans back west, especially after the crushing defeats of the German Army at both Kursk and Stalingrad and the Germans' failure to take Leningrad (St. Petersburg). The Luftwaffe saw action on many fronts, including in North Africa in support of ground operations conducted by General Erwin Rommel's Afrika Korps, and in the offensives against Yugoslavia and Greece prior to the invasion of the USSR in June 1941. Many Luftwaffe units were stationed in Italy, including after the Italians switched sides in September 1943 and remained there until the end of the war in May 1945. There were units also present in Romania, since fighter units stationed there were charged with the protection of the oilfields at Ploesti that were providing vital fuel for the German war machine in its continuation of its offensive against the USSR. Afrika Korps One of the unique characteristics of the Luftwaffe (as opposed to other independent air forces) was the possession of an elite organic paratrooper force (Fallschirmjäger). These saw action during 1940–1941, most notably in the capture of the Belgian army fortress at Eben-Emael in May 1940 and the island of Crete in May 1941. However, more than 3,000 Fallschirmjäger were killed during the Crete operation, and a shocked Adolf Hitler ordered these elite paratroopers would never be used for such large-scale operations again, but only for smaller-scale operations, such as the successful rescue of Benito Mussolini, the then-deposed dictator of Italy, in 1943. This put paid to a proposal (Operation Herkules) to seize Malta and eliminate the threat to Rommel's supply lines. Although night fighting had been undertaken in embryonic form way back in World War I, the German night fighter force, the Nachtjagd, had virtually to start from scratch when British bombers began to attack targets in Germany in strength from 1940 as far as tactics were concerned. A chain of radar stations was established all across the Reich territory from Norway to the border with Switzerland known as the "Kammhuber Line", named for Generalleutnant Josef Kammhuber, and nearby night fighter wings, Nachtjagdgeschwader (NJG), were alerted to the presence of the enemy. These wings were equipped mostly with Messerschmitt Bf 110 and Junkers Ju 88 aircraft, which would later be outfitted with the Lichtenstein nose-mounted radar. Junkers Ju 88 The Heinkel He 219 Uhu (Owl) was considered one of the best night fighters in the Luftwaffes inventory, yet thankfully for the Allies, not enough of them were built to stem the tide of bombers, which became effective at using strips of aluminium foil called "Window" (American name, chaff; German, Duëppel) to jam the radar signals. Two notable names amongst the night fighter pilots were Helmut Lent, who shot down 110 enemy aircraft before being killed in a landing accident in October 1944, and Wolfgang Schnaufer, who shot down 102 enemy aircraft and survived the war, only to die in a car crash in France in 1950. Wolfgang Schnaufer After playing a pioneering role in the development of aircraft powered by jet engines ("TL Triebwerke") with prototypes such as the Heinkel He 178 and Heinkel He 280, the Luftwaffe became the first air force in the world to press an operational jet fighter into service—the twin-engine Messerschmitt Me 262. The aircraft was still plagued by reliability problems of its powerplants; however, while the Junkers Jumo 004 engines were of the advanced axial-flow design, they suffered from a lack of high-quality strategic materials required during the manufacturing process, a result of the Allied bombing offensive and the turn of war fortunes for Germany. The Me 262 was soon joined by other highly advanced aircraft designs, such as the Arado Ar 234 twin- and four-engine jet bomber/reconnaissance aircraft, the Heinkel He 162 single-engine jet fighter (powered by a BMW jet engine), the Messerschmitt Me 163 rocket fighter and others. A variety of further highly advanced aircraft designs, such as the Horten Ho 229 flying wing (originally designated Horten Ho IX and later to be manufactured by the Gothaer Waggonfabrik aircraft factory), were either at the testing stage or even ordered into production by the time the war ended. The German aviation industry also developed the first cruise missile used operationally on large scale, the Fieseler Fi 103 (V-1), and the first ballistic missile, the Aggregat 4 (A-4, V-2). These were Hitler's vaunted Vergeltungswaffen (vengeance or retaliation weapons). As modern as these aircraft were, they could not prevent Germany's total defeat in the air. The Luftwaffe lacked fuel, trained pilots, organisational unity and "safe" airfields. The Luftwaffes final offensive was on January 1, 1945, when it launched Operation Bodenplatte (Baseplate). The idea was to destroy as many Allied aircraft on the ground as possible, yet the Germans lost over 300 aircraft and were henceforth entirely on the defensive as the western Allies and the Soviets closed in and invaded the Reich itself. The Allies were able to harvest Germany's advanced technical efforts as many German aircraft were abandoned after being deliberately wrecked for the most part; Operation Paperclip, for example, was one of many designed in 1944–45 to obtain either technical specimens, data, or the design personnel themselves and "evacuate" them to the United States, England, the USSR or France. Many aircraft designers were also captured by the Red Army and sent to the USSR to design and build potential fighters and bombers for the Soviet Army and Navy Air Forces. This research benefited the development of the NAA F-86, Hawker Hunter, and MiG-15, and directly produced the Yak-9 and -15 (little more than copies of the Focke-Wulf P.011-45). The early U.S. and Soviet space programs also employed German hardware and were staffed with many German scientists and engineers, the most famous of which was Wernher von Braun, subsequently the head of the design team of the American Saturn V moon rocket. Saturn V Amongst the designers sent to Russia was Dr. Hans Wocke, the man who designed the world's first forward-swept-wing jet bomber, the Junkers Ju 287, the first prototype of which, the Ju 287V1, had flown during the war on test flights. The Ju 287 design work was incorporated into the Junkers EF (Erprobungsflugzeug = test aircraft) 140 bomber prototype, yet neither this nor any other aircraft designed by the Germans would ever be accepted into the Soviet Army or Navy Air Forces, since the Germans themselves were technically prisoners and were denied access to the latest facilities for designing and perfecting modern warplanes. Most of the captured designers had been allowed to return to either West or East Germany by the end of 1953. Junkers Ju 287 Throughout the history of the Third Reich, the Luftwaffe had only two commanders-in-chief. The first was, of course, Göring, yet he was fired by Hitler near the end of the war in Europe on account of his having contacted (western) Allied forces without his authorisation with a view to securing a ceasefire before the Soviets overran Berlin. Hitler thus appointed Generaloberst Robert Ritter von Greim as the second (and last) commander-in-chief of the Luftwaffe, concomitant with his promotion to Generalfeldmarschall, the last German officer in World War II to be promoted to the highest rank. One other officer, who happened to have been promoted to this rank himself, had been Wolfram von Richthofen, the cousin of the "Red Baron", but he had retired in late 1944 on medical grounds and would die of a brain tumour while in American captivity at Bad Ischl on July 12, 1945. Operational and training units of the Luftwaffe were organised roughly similarly to those of the U.S. Army Air Corps (which later became the U.S. Army Air Forces). Fighter wings (Jagdgeschwader) (JG) consisted of groups (Gruppen), which in turn consisted of fighter squadrons (Jagdstaffel). Hence, Fighter Wing 1 was JG 1, its first group was I/JG 1 and its first squadron was 1./JG 1. (As a point of interest, JG 1 was operating the aforementioned Heinkel He 162 at the end of the war. In the final two months, JG 1 lost 22 of them, mostly in crashes, resulting in ten pilots being killed and another six injured.) Similarly, a bomber wing was a Kampfgeschwader (KG), a night fighter wing was a Nachtjagdgeschwader (NJG), a dive-bomber wing was a Stukageschwader (StG), and units equivalent to those in RAF Coastal Command, with specific responsibilities for coastal patrols and search and rescue duties, were Küstenfliegergruppen (Kü.Fl.Gr.). Specialist bomber groups were known as Kampfgruppen (KGr). Each Geschwader was commanded by a Kommodore, a Gruppe by a Kommandeur, and a Staffel by a Staffelkapitãn. However, these were appointments, not ranks, within the Luftwaffe. Usually, the Kommodore would hold the rank of Oberstleutnant (lieutenant colonel) or, exceptionally, an Oberst (colonel). Even a Leutnant (second lieutenant) could find himself commanding a Staffel. Some of the Luftwaffe's units came from countries under German control such as 13 JG 52 (Slovakia) and Luftwaffen-Legion Lettland (Latvia). From before the war, the German Ministry of Propaganda disseminated a magazine specialising in the Luftwaffe called Der Adler (The Eagle), not just in German but also in the first languages, including French, of several countries which eventually became incorporated into the Reich territory. While the U.S. remained officially neutral (from September 1939 until December 1941), the magazine was also published in English. Many colour photographs of the Luftwaffe in action during the war originally came from this publication. See also
- List of aircraft of the WW2 Luftwaffe
- Luftwaffe serviceable aircraft strengths (1940-1945)

Cold war

Luftwaffe serviceable aircraft strengths (1940-1945) Following the war, German aviation in general was severely curtailed, and military aviation was completely forbidden when the Luftwaffe was officially disbanded in August 1946 by the Allied Control Commission. This changed when West Germany joined NATO in 1955, as the Western Allies believed that Germany was needed in view of the increasing threat militarily from the USSR and its Warsaw Pact allies. Throughout the following decades, the West German Luftwaffe was equipped mostly with U.S.-designed aircraft manufactured locally under licence. All aircraft sported—and continue to sport—the Iron Cross on the fuselage, harking back to the days of World War I, while the national flag of West Germany could be seen on the tailplanes. Many well-known fighter pilots, who had fought with the Luftwaffe in World War II, joined the new post-war air force and underwent refresher training in the U.S. before returning to West Germany to upgrade on the latest U.S.-supplied hardware. These included Erich Hartmann, the highest-ever scoring ace (352 enemy aircraft destroyed), Gerhard Barkhorn (301), Günther Rall (275) and Johannes Steinhoff (176). Steinhoff, who suffered a crash in a Messerschmitt Me 262 shortly before the end of the war which resulted in lifelong scarring of his face and other parts of his body, would eventually become commander-in-chief of the Luftwaffe, with Rall as his immediate successor. Hartmann retired as an Oberst (colonel) in 1970 aged 48. The aforementioned Josef Kammhuber also served with the post-war Luftwaffe, retiring in 1962 as Inspekteur der Bundesluftwaffe. During the 1960s, the "Starfighter crisis" was a big problem for German politics, as many of these Lockheed F-104 fighters crashed after being modified to serve for Luftwaffe purposes. Therefore, the Starfighter was dubbed the "widow maker" (German: Witwenmacher). (It is of note that the F-104 served with the USAF for only a few years.) On the other hand, the Canadian version of the North American F-86 Sabre, the Canadair CL-13, enjoyed a long career with Luftwaffe fighter squadrons, since seventy-five of them entered service in and after 1957. The United States provides nuclear weapons for use by Germany under a NATO nuclear sharing agreement. As of 2005, 60 tactical B61 nuclear bombs are provided, stored at Büchel and Ramstein Air Bases, which in time of war would be delivered by Luftwaffe Panavia Tornados [http://www.nrdc.org/nuclear/euro/euro.pdf]. Many countries believe this violates Articles I and II of the Nuclear Non-Proliferation Treaty. The DDR's equivalent air force the Luftstreitkräfte, sharing the name with Germany's WWI air force. It was supplied exclusively with Eastern Bloc-produced aircraft and served primarily as an extension of Red Air Force units in Eastern Germany. The Luftstreitkräfte was unique among Warsaw Pact countries in that it was often equipped with Soviet-standard combat aircraft, instead of downgraded export models. As an extension of Soviet air power, the Luftstreitkräfte enjoyed less autonomy than other Eastern Bloc air forces.

Reunification

Warsaw Pact Typhoon. The name "Typhoon" caused controversy since the Hawker Typhoon was an RAF ground-attack aircraft which destroyed many targets in support of the ground forces invading France in June 1944 and afterwards.]] The air force of the Communist German Democratic Republic /East Germany used the same name as the one used during World War I, that is, the Luftstreitkräfte. It flew Soviet-built aircraft, such as the Sukhoi Su-7 "Fitter" and the more famous Mikoyan-Gurevich (MiG) family of aircraft, such as the MiG-21, MiG-23 and MiG-29 fighters. Unlike the West German Luftwaffe, however, the markings sported on the aircraft reflected the identity of the country as belonging to the Communist bloc. As such, the markings consisted of a diamond-shaped design, in which could be seen the vertically oriented three stripes in black, red and gold surmounted by the stylised hammer, compass and wreath-like ears-of-grain design, which was also seen on the Flag of East Germany, although the stripes were a 90-degree orientation from those to be seen on either national flag of the two German nations between 1959 and 1990. After the GDR and West Germany were reunified in October 1990, the aircraft of the Luftstreitkräfte were taken over by the unified Federal Republic of Germany, and their GDR markings replaced by those of the Iron Cross, thus creating the somewhat anomalous situation of Soviet-built aircraft serving in a NATO air force. However, most of these would eventually be taken out of service altogether, in many cases being sold to the new Eastern European allies now part of NATO, such as Poland and the Baltic states. The exception to this is the 73rd Steinhoff Fighter Wing in Laage, Germany. The pilots of this squadron fly MiG-29s acquired during the reunification and are the most experienced MiG-29 pilots in the world. One of their primary duties is to serve as aggressor pilots, training other pilots in dissimilar combat tactics. The United States has sent a group of fighter pilots to Germany during the Red October exercise to practice real tactics against the type aircraft they are most likely to meet in real combat. Since the 1970s, the Luftwaffe of West Germany and later the reunited Germany has actively pursued the construction of European combat aircraft such as the Panavia Tornado and more recently the Eurofighter Typhoon. Eurofighter, Labrador]] In March 1999, for the first time since 1945, the Luftwaffe engaged in combat operations as part of the NATO-led Kosovo War. This event was noted as significant in the British press with The Sun running the headline "Luftwaffe and the RAF into battle side by side"[http://news.bbc.co.uk/1/hi/world/europe/303314.stm]. No strike sorties were flown, and the role of the Luftwaffe was restricted to providing support, for example, with suppression of enemy air defence (SEAD) sorties. No Luftwaffe aircraft were lost during the campaign, but the force's role proved to be controversial in Germany because of the strong pacifist sentiment still present in the population that is opposed to the use of force by Germany in international affairs. Moreover, there were constitutional concerns, because Germany was not and, indeed, still is not—allowed to participate in "wars of aggression" owing to its 1949 Grundgesetz ("Basic Law" - constitution). Because of something like a paradigm shift, Germany can use its Luftwaffe for crisis reaction and conflict prevention.

External links

- [http://www.luftwaffe.de Luftwaffe official website (in German)]
- [http://www.luftarchiv.de The archive about the assignment of persons and material of the German Air Force in the Second World War]
- [http://www.galaxy.com/galaxy/Leisure-and-Recreation/Aviation/History/World-War-II Galaxy.com (a link to other aviation web sites of interest)]
- [http://www.DDR-LUFTWAFFE.de German Democratic Republic (1955-1990) Air Force website (in German)]
- [http://www.lwag.org/index.php Luftwaffe Archives & Records Reference Group (LWAG) (dedicated to research into the history of the Luftwaffe of the Third Reich)]
- [http://www.luftwaffe-experten.co.uk Luftwaffe Experten (detailing many aspects of 1939-1945 Luftwaffe operations)]
- [http://www.luftwaffe.cz/experten.html Luftwaffe Experten (English-language Czech website containing biographies of leading Luftwaffe pilots)]
- [http://www.luft46.com Luft46.com (paintings of "might-have-been" Luftwaffe aircraft)]
- [http://www.ww2incolor.com/gallery/german-luftwaffe Color Photographs of German Luftwaffe] - rare color photographs of the Luftwaffe during WWII
- [http://www.ww2images.com ww2images.com (photos of World War II aircraft from all nations)]
- [http://www.ww2.dk/ Luftwaffe, 1933-1945]
- [http://forum.12oclockhigh.net/ 12 O'clock High - Luftwaffe and Allied Forces discussion forum]

Select bibliography

There have been literally hundreds of books, magazines and articles written about the Luftwaffe. It is only possible to list a select few here.
- Aders, Gebhard (1992), History of the German Night-Fighter Force, 1917-1945 (edited and translated by Alex Vanags-Baginskis), Crecy. ISBN 0947554211. (Originally published by Jane's in 1979.)
- Amadio, Jill (2002), Günther Rall: A Memoir, Seven Locks Press. ISBN 0971553300.
- Galland, Adolf (2000 [1957]), The First and the Last, Buccaneer Books, Inc. ISBN 0899667287.
- Green, William (1990), Warplanes of the Third Reich, Galahad. [Second edition, following from original work published in 1970.] ISBN 0883656663.
- Held, Werner and Nauroth, Holger (1982), The Defence of the Reich: Hitler's Nightfighter Planes and Pilots (translated by David Roberts), London, Arms and Armour Press. ISBN 0853684146.
- Mermet, Jean-Claude and Ehrengardt, Christian-Jacques (2002), Les Jets de la Luftwaffe: Aéro-Journal Hors-Série No.4, Aéro-Éditions International (French language edition only). ISSN 03361055.
- Orbis Publishing Limited, London (1974-77), Wings, a part-work encyclopedia of aviation in eight volumes, which included many articles about the battles during World War II in which the Luftwaffe took part, as well as biographies of some of its high-profile airmen.
- Orbis Publishing Limited, London (1981-84) (second edition), World War II, a part-work encyclopedia in eight volumes about the 1939-1945 War.
- Philpott, Bryan (1986), History of the German Air Force, Hamlyn. ISBN 0600502937.
- Price, Alfred (2005), Battle Over The Reich: The Strategic Bomber Offensive Against Germany 1939-1945, Classic Publications. [Revised, second edition based on the previous work with the same title first published in 1973.] ISBN 1903223474.
- Price, Alfred (2000), Blitz on Britain, 1939-1945, Sutton. [Revised edition of Blitz on Britain : the bomber attacks on the United Kingdom, 1939-1945, first published by Ian Allan in 1977]. ISBN 0711007233 (1977 edition).
- Sobolev, D. A. and Khazanov, D.B. (2001), The German Imprint on the History of Russian Aviation, Moscow, Rusavia (English edition). ISBN 5900078086.
- Wood, Tony, and Gunston, Bill (1984), Hitler's Luftwaffe: A Pictorial History and Technical Encyclopedia of Hitler's Air Power in World War II, Book Sales (originally published by Salamander Books). ISBN 0890097585. Category:Air forces Luftwaffe Category:Military of Germany Category:German loanwords ja:ドイツ空軍 simple:Luftwaffe

World War II

, and the use of new, extremely devastating weapons such as the atom bomb. From top going counterclockwise: Allied landing on D-Day 1944, the Nuremberg Rally 1936, the Nagasaki atom bomb 1945, the Soviet flag over the Reichstag in Berlin 1945 and the Gate of Auschwitz.]] World War II, also known as the Second World War, was a mid-20th Century conflict that engulfed much of the globe and is accepted as the largest and deadliest continuous war in human history. It was the first time that a number of newly developed technologies, including nuclear weapons, were used against either military or civilian targets. World War II resulted in the direct or indirect death of anywhere from 50 to 60 million or more people, over 3% of the world population at that time. It is estimated to have cost more money and resources than all other wars combined: about 1 trillion US dollars in 1945 (adjusted for inflation; roughly 10.5 trillion in 2005), not including subsequent reconstruction [http://www.historychannel.com/worldwartwo/?page=triumph5]. The outcomes of the war, including new technology and changes to the world's geopolitical, cultural and economic arrangement, were unprecedented. The conflict began by most Western accounts on September 1 1939 with the German invasion of Poland (the Pacific war is taken to have started on July 7 1937 with the Japanese attack on China) and lasted until mid-1945, involving many of the world's countries. Virtually all countries that participated in World War I were involved in World War II. Britain, France, Australia and New Zealand declared war on Germany on September 3, 1939 and Canada followed on September 10, 1939. The United States entered the conflict in December of 1941 after the Japanese attack on Pearl Harbor.

Summary

Attributed in varying degrees to the Treaty of Versailles, the Great Depression, and the rise in nationalism, racism, fascism, National socialism, Japanese imperialism, and militarism, the causes of the war are a matter of debate. The war was fought between the Axis Powers and the Allies. The Axis initially consisted of an alliance between Germany and Italy, which later expanded to include Japan and Eastern European countries such as Romania and Bulgaria. Some of the nations that Germany conquered sent military forces, particularly to the Eastern front. Among the expeditionary forces that joined Germany were forces from Vichy France, The Netherlands, Belgium, Spain (though Spain was itself a neutral country) and armies of Russians and Ukrainians under the command of the general Andrey Vlasov. The Allies were initially the United Kingdom, including the Commonwealth, France and Poland, later joined by the USSR, the United States of America and China. Fighting occurred across the Atlantic Ocean, in Western and Eastern Europe, in the Mediterranean Sea, Africa, the Middle East, in the Pacific and South East Asia, and it continued in China. In Europe, the war ended with the surrender of Germany on 8 May 1945 (V-E and Victory Days), but continued in Asia until Japan surrendered on 15 August 1945 (V-J Day). At least 50 million people died as a result of the war. This figure includes acts of genocide such as the Holocaust and General Ishii Shiro's Unit 731 experiments in Pingfan, incredibly bloody battles in Europe and the Pacific Ocean, and massive bombings of cities, including the atomic bombings of Hiroshima and Nagasaki in Japan and the firebombing of Dresden (and even worse but less known) of Pforzheim in Germany. Few areas of the world were unaffected; the war involved the "home front" and bombing of civilians to a new degree. Atomic weapons, jet aircraft, rockets and radar, the blitzkrieg, or "lightning war", the massive use of tanks, submarines, torpedo bombers and destroyer/tanker formations, are only a few of many wartime inventions and new tactics that changed the face of the conflict. Post–World War II Europe was partitioned into Western and Soviet spheres of influence, the former undergoing economic reconstruction under the Marshall Plan and the latter becoming satellite states of the Soviet Union. This partition was, however, informal; rather than coming to terms about the spheres of influence, the relationship between the victors steadily deteriorated, and the military lines of demarcation finally became the de facto country boundaries. Western Europe largely aligned as NATO, and Eastern Europe largely as the Warsaw pact countries, alliances which were fundamental to the ensuing Cold War. In Asia, the United States' military occupation of Japan led to Japan's democratisation. China's civil war continued through and after the war, resulting eventually in the establishment of the People's Republic of China. The war sparked a wave of independence for colonies of European powers, who were exhausted from fighting the war. There was a fundamental shift in power from Western Europe to the new superpowers, the United States and the Soviet Union, though there were few actual boundary changes. __TOC__

Causes

People's Republic of China]] Main articles: Causes of World War II, Events preceding World War II in Europe, Events preceding World War II in Asia The causes of World War II are naturally a debated subject, but a common view, particularly among the allies in the early post-war years, ties them to the expansionism of Germany and Japan: Germany had lost wealth, power and status following the First World War and the expansion was to make Germany great again.
- In Germany there was a strong desire to escape the bonds of the World War I Treaty of Versailles, and eventually, Hitler and the Nazis assumed control of the country. They led Germany through a chain of events: rearmament, reoccupation of the Rhineland, a merger with Austria (Anschluss), incorporation of Czechoslovakia and finally the invasion of Poland.
- In Asia, Japan's efforts to bec