BMW 132

BMW 132. The BMW 132 was a nine-cylinder, air-cooled radial aircraft engine produced in Germany in the 1930s and 1940s. It was a licensed development of the American Pratt & Whitney R-1690 Hornet, extensively refined by BMW engineers for improved performance and reliability. This powerplant became a cornerstone for German civil and military aviation, powering numerous iconic transport and bomber aircraft throughout the Second World War.

Development and design

The genesis of the BMW 132 lies in BMW's 1929 acquisition of a license to manufacture the Pratt & Whitney R-1690 Hornet from the United States. Under the leadership of chief engineer Max Friz, the company's BMW Flugmotorenbau division in Eisenach undertook significant modifications to the original design. Key improvements included the adoption of a forged aluminum crankcase, sodium-cooled exhaust valves, and a redesigned cylinder head with better cooling fin geometry. These enhancements, coupled with the use of higher-octane aviation fuel, allowed for increased compression ratios and superior power output compared to the American progenitor. The development program, which began in earnest in 1932, resulted in a robust and dependable engine that first ran successfully in 1933, entering production shortly thereafter.

Operational history

The BMW 132 entered widespread service with Lufthansa and the nascent Luftwaffe in the mid-1930s, quickly establishing a reputation for durability and ease of maintenance. It became the standard powerplant for the ubiquitous trimotor transport, the Junkers Ju 52, which served as the workhorse of German air transport. During the Spanish Civil War, Ju 52s powered by the BMW 132 were used extensively as bombers and transports by the Condor Legion, providing valuable operational experience. Throughout the Second World War, the engine saw continuous use in transport, maritime patrol, and training roles, notably in the Focke-Wulf Fw 200 Condor long-range reconnaissance aircraft and the Junkers Ju 86. Its reliability made it a favored choice for demanding over-water and Arctic missions.

Variants

A wide array of variants was produced to meet different performance and installation requirements. The initial production model was the 132A, followed by the more powerful 132D. The 132H and 132K series featured a two-speed supercharger for improved high-altitude performance. Specialized versions included the 132Z, which coupled two engines to drive a single propeller via a common gearbox for the Focke-Wulf Fw 189, and the 132N, a low-compression model designed for operation in tropical climates. Military models often incorporated a Vokes air filter for desert operations. Continuous development increased power output from approximately 660 horsepower in early models to over 960 horsepower in the final 132L variant.

Specifications (BMW 132)

* **Type:** Nine-cylinder single-row supercharged air-cooled radial engine * **Bore:** 155.5 mm (6.12 in) * **Stroke:** 174 mm (6.85 in) * **Displacement:** 27.7 L (1,690 cu in) * **Length:** 1,357 mm (53.4 in) * **Diameter:** 1,380 mm (54.3 in) * **Dry weight:** 465 kg (1,025 lb) * **Valvetrain:** Two overhead valves per cylinder, pushrod-actuated * **Supercharger:** Gear-driven centrifugal type, single-speed or two-speed * **Fuel system:** BMW-Hirth injection carburetor * **Oil system:** Dry sump with pressure scavenge * **Cooling system:** Air-cooled * **Power output:** 660–960 hp (492–716 kW) depending on variant * **Compression ratio:** 6.5:1 to 7.2:1

Applications

The BMW 132 was the primary engine for several of the most significant German aircraft of its era. Its most famous application was the tri-motor Junkers Ju 52, used by Lufthansa and the Luftwaffe. It also powered the Focke-Wulf Fw 200 Condor maritime patrol bomber, the Junkers Ju 86 medium bomber and airliner, the Blohm & Voss Ha 139 flying boat, and the Arado Ar 196 shipboard reconnaissance floatplane. Furthermore, it was used in the Focke-Wulf Fw 189 tactical reconnaissance aircraft and various training aircraft like the Siemens-Schuckert and Bücker Bü 131 advanced trainers. Post-war, surplus engines were utilized in French aircraft such as the Nord Noralpha.

Category:Aircraft piston engines Category:BMW aircraft engines Category:Radial aircraft engines