GERMAN DEVELOPMENT: Work on the gas turbine engine was going on in Germany concurrently with Whittle’s work in Britain. Serious efforts toward aircraft jet propulsion were started in the mid 1930s. The main German development took place in 1940, when  Willi Messerschmitt produced  the Me 262, a 805 Km/h fighter, powered by two axial-flow engines, the Jumo 109-004a. More than 1600 Me 262 fighters were built in the closing stages of World War II, but they reached operational status too late to challenge the overwhelming air superiority gained by the Allies seriously.     TYPICAL OPERATION: A gas turbine engine is an internal combustion engine that consists of three main parts: The axial-flow compressor The combustor The turbine The front, or inlet, duct is almost entirely open to permit outside air to enter the front of the engine. The compressor works on this incoming air and sends it to the combustion or burner section at high pressures. In the burner section, the fuel, similar to kerosene, is sprayed and mixed with the compressor air. The mixture is then ignited by devices similar to spark plugs. Extremely hot gas streams from the combustor and escapes through the blades of the turbine, spinning them at high speed. The turbine extracts most of the energy from the gas stream and uses this energy to turn the compressor and the accessories. After leaving the turbine, there is still enough pressure left to force the hot gases through the exhaust duct and jet nozzle at the rear of the engine at very high speed.     AXIAL-FLOW COMPRESSOR ENGINES: The Me 262 fighter used an axial-flow compressor engine, chosen because of its ability to handle large volumes of airflow. Unfortunately, it is more susceptible to external-object damage, it is expensive to manufacture and it is very heavy in comparison with the centrifugal compressor with the same compression ratio. The axial-flow compressor is made up of a series of rotating airfoils called rotor blades, which are made up of an alloy of stainless steel containing Nickel (30%) and Chromium (15%), and a stationary set of airfoils called stator vanes made up of a particular steel alloy containing Chromium and Manganese. A stage is a row of rotating and stationary blades. The entire compressor is made up of a series of alternating rotor and stator vane stages. As its name implies, the air is being compressed in a direction parallel to the axis of the engine. This axial compressor has the advantage of being capable of very high compression ratios with relatively high efficiency with respect to the British centrifugal compressor engines developed in the same years.     COMBUSTION CHAMBER: In the Jumo 109-004A/B/C/D engines there are six combustion chambers located around the structure. The combustion chamber is able to move axially as a consequence of the thermic dilatation that happens during ignition. The first stage consists in the separation of the primary and secondary  air as shown in the figure: Then the fuel is forced to go out against the stream, is mixed with the primary air and ignited. A bulkhead prevents the combustion chamber from being subject to the high temperatures caused by the hot exhaust gases. After they have passed through the chamber, the secondary air is added to them to prevent the overheating of the turbine.     TURBINE CONSTRUCION: The turbine wheel is one of the most highly stressed parts of the Jumo 109-004. The turbine assembly is made up of two main parts, the disk and the blades. The disk or wheel is a statically and dynamically balanced unit of specially alloyed steel containing mainly Chromium, Vanadium but also Manganese, Magnesium, Silicon, and Carbon. The blades are attached to the disk by means of gudgeon pins designed to allow for different  rates of expansion between the disk and the blade while still holding the blade firmly against centrifugal loads. The 61 blades of the Jumo turbine engine are made up of stainless steel containing mainly Nickel and Chromium (0.15%C; 0.7%Si; 0.6%Mn; 1.7%Ti; 30%Ni; 19%Cr). The buckets are empty inside and supported by an air cooling system.     JET NOZZLE: The nozzle of the Jumo 109-004 is variable, so as to maintain sufficient efficiency at low speed. In the part near to the engine there is a device that can move along the structure of the engine for 0.20 meters, restricting the section of the nozzle. By doing that, the pilot can also control the temperature of the exhaust gases.