How A Work BMW 801 Engine


The BMW 801 was a powerful German 41.8-litre 2,550 cu in air-cooled 14-cylinder-radial aircraft engine built by BMW and used in a number of German Luftwaffe aircraft of World War II.

Production versions of the twin-row engine generated between 1,560 and 2,000 PS 1,540–1,970 hp, or 1,150–1,470 kW. It was the most produced radial engine of Germany in World War II with more than 61,000 built.

The 801 was originally intended to replace existing radial types in German transport and utility aircraft. At the time, it was widely agreed among European designers[citation needed that an inline engine was a requirement for high performance designs due to its smaller frontal area and resulting lower drag.

Kurt Tank successfully fitted a BMW 801 to a new fighter design he was working on, and as a result the 801 became best known as the power plant for the famous Focke-Wulf Fw 190. The BMW 801 radial also pioneered the use of what would today be designated an engine control unit: its Kommandogerät engine management system took over the operation of several aviation engine management control parameters of the era, allowing proper operation of the engine with just one throttle lever.

The new design was given the name BMW 801 after BMW was given a new block of "109-800" engine numbers by the RLM to use after their merger with Bramo. The 801 retained the 139's older-style single-valve intake and exhaust, while most in-line engines of the era had moved to either three as Junkers had done or four valves per cylinder, or in British use for their own radials, sleeve valves. Several minor advances were worked into the design, including the use of sodium-cooled valves and a direct fuel injection system, manufactured by Friedrich Deckel AG of Munich.

The supercharger was rather basic in the early models, using a single-stage two-speed design directly geared to the engine unlike the DB 601's hydraulically clutched version which led to rather limited altitude performance, in keeping with its intended medium-altitude usage.

One key advancement for the 801 was the Kommandogerät command-device, a mechanical-hydraulic unit that automatically adjusted engine fuel flow, propeller pitch, supercharger setting, mixture and ignition timing in response to a single throttle lever, dramatically simplifying engine control. The Kommandogerät could be considered to be a precursor to the engine control units used for many vehicles' internal combustion engines of the late 20th and early 21st centuries.

There was a considerable amount of wind tunnel work done on the engine and BMW-designed forward cowling incorporating the engine's oil cooler at the Luftfahrtforschungsanstalt LFA facility in Völkenrode, leading to the conclusion it was possible to reduce drag equivalent to 150–200 hp 110–150 kW;

150–200 PS. It also maximized the use of positive air pressure to aid cooling of cylinders, heads, and other internal parts.