__NOTOC__ The BMW VII was a

water-cooled Cooling tower and water discharge of a nuclear power plant Water cooling is a method of heat removal from components and industrial equipment. Evaporative cooling using water is often more efficient than air cooling. Water is inexpensive and non ...

twelve-cylinder engine derived from the successful

BMW VI The BMW VI was a water-cooled V-12 aircraft engine built in Germany in the 1920s. It was one of the most important German aero engines in the years leading up to World War II, with thousands built. It was further developed as the BMW VII and B ...

. The engine was not as popular as the VI, due in no small part to the

Great Depression The Great Depression (19291939) was an economic shock that impacted most countries across the world. It was a period of economic depression that became evident after a major fall in stock prices in the United States. The economic contagio ...

, and only a small number were built. Experiments with

supercharging In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement. The current categorisation is that a supercharger is a form of forced induct ...

led to the related BMW IX.

Design and development

The main change from the VI to the VII was the addition of a 0.62 ratio propeller reduction gearing system, allowing the engine to run at higher RPM, and thus higher power settings, while still efficiently driving the same propellers. A more minor change was the movement of the

magneto A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, ...

s from the back of the

cylinder bank The engine configuration describes the fundamental operating principles by which internal combustion engines are categorized. Piston engines are often categorized by their cylinder layout, valves and camshafts. Wankel engines are often categorize ...

s to the front, which allowed easier access for maintenance, (similar changes to the original six-cylinder

BMW V __NOTOC__ The BMW V was a six-cylinder, water-cooled inline aircraft engine built in Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe a ...

led to the BMW VIII) . The crankcase was offered in

aluminum alloy An aluminium alloy (or aluminum alloy; see spelling differences) is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There are two principal ...

or Elektron.

Operational history

The engine was first built in 1928 and passed its acceptance tests in June 1930. Only a few examples of the BMW VII went into operation, in the single-engined version of the

Junkers Ju 52 The Junkers Ju 52/3m (nicknamed ''Tante Ju'' ("Aunt Ju") and ''Iron Annie'') is a transport aircraft that was designed and manufactured by German aviation company Junkers. Development of the Ju 52 commenced during 1930, headed by German Aeros ...

, for example, and in the Dornier Wal which

Wolfgang von Gronau Hans Wolfgang von Gronau (25 February 1893 - 17 March 1977) was a German aviation pioneer. Biography Wolfgang von Gronau was born in Berlin in a family hailing from the ancient dynasty of the House of Berg. He was the son of artillery General Han ...

flew around the world in 1932. The VII was also used for forced-aspiration experiments with a "mixture blower" (a radial fan located behind the

carburettor A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meterin ...

); this led in due course to the development of the BMW IX aircraft engine.

Variants

;Low compression: A low compression variant ran at 5.5:1 compression ratio, delivering at 1,565 rpm ;Medium compression: A medium compression variant ran at 6:1 compression ratio, delivering at 1,650 rpm ;BMW VIIaU:A high compression variant running at 7.3:1 compression ratio, delivering for take-off.

Specifications (variant)

References

{{BMW aeroengines BMW aircraft engines 1920s aircraft piston engines