The BMW 003 was an early turbojet engine produced in Germany during World War II. Work on its design began earlier than the contemporary Junkers Jumo 004 engine, but prolonged developmental problems meant that the BMW 003 entered production much later, and the aircraft projects that had been designed with it in mind had been re-engined with the Jumo powerplant instead. The most famous case of this was the Messerschmitt Me 262, and the same was true of the Arado Ar 234 and Gotha Go 229. The only production aircraft to use the BMW 003 were the Heinkel He 162 and late, four-engined versions of the Arado Ar 234. After the war, the engine continued to be produced in the Soviet Union, and also formed the basis for turbojet development in Japan during the war, and France afterwards. Some 500 engines were built in Germany, but very few were ever installed in aircraft.
The practicality of jet propulsion had been demonstrated in Germany in early 1937 by Hans von Ohain working with the Heinkel company. Recognising the potential of the invention, the Reichsluftfahrtministerium (RLM - Reich Aviation Ministry) encouraged Germany's aero engine manufacturers to begin their own programmes of jet engine development. The BMW 003 began development as a project of the Brandenburgische Motorenwerke (The Brandenburg Motor Works, known as "Bramo") under the direction of Hermann Ístrich and assigned the RLM designation 109-003 (the 109- prefix common to all jet engine projects). Bramo was also developing another turbojet, the 109-002. In 1939, BMW bought out Bramo, and in the acquisition, obtained both engine projects. The 109-002 had a very sophisticated contra-rotating compressor design intended to eliminate torque, but was abandoned in favour of the simpler engine, which in the end proved to have enough development problems of its own.
Construction began late in the same year and the engine ran for the first time in 1940, but produced less than half of the thrust expected - 260 kg instead of 640 kg. The first flight test took place in mid-1941, mounted underneath a Messerschmitt Bf 110. Problems continued, however, meaning that while the Me 262 (the first aircraft intended fo the engine) was ready for flight-testing, there were no powerplants available for it, meaning that it had to begin testing with a piston engine in the nose instead. It was not until November 1941 that the Me 262 was flown with BMW engines, which both failed during the test, the prototype having to return to the airfield on the power of the piston engine still fitted.
The powerplant was abandoned for the Me 262, but work on it continued at BMW, and by late 1942 it had been made far more powerful and reliable. With the new designation 109-006 the improved engine was flight tested under a Junkers Ju 88 in October 1943 and was finally ready for mass production in August 1944, in time only to power last-ditch projects like the He 162.
One late version of the engine added a small rocket motor (BMW 109-718) at the rear of the engine, which added some 1,000 kg of thrust for take off and short dashes. In this configuration, it was known as the BMW-003R and was tested on a single Me 262, and perhaps a He 162 as well.
The BMW-003 was intended for export to Japan, but working examples of the engine were never supplied. Instead, Japanese engineers used drawings and photos of the engine to design an indigenous turbojet, the Ne-20.
Following the war, two captured BMW-003s powered the prototype of the first Soviet jet, the Mikoyan-Gurevich MiG-9, and copies of this engine, designated RD-20 powered this aircraft in series production.
At the end of the war, Ístrich fled to Switzerland, but soon accepted an offer from the French government to work on further refining the -003 for Voisin, a division of SNECMA. The result was the Atar engine, which in various forms powered French military aircraft for decades to come.