Anzani 20
| Industry | Aircraft engines |
|---|---|
| Founded | 1913 |
| Products | Aircraft radial engines, including the Anzani 20 |
The Anzani 20, introduced in 1913, was a pioneering 20-cylinder air-cooled radial engine arranged in four rows. It represented the earliest example of a four-row radial configuration and ranked among the most powerful powerplants of its time, although its operational deployment was relatively scarce.
Development
In 1912, Anzani had already created the world's inaugural two-row radial engine, the ten-cylinder Anzani 10, available in two variants. The larger model featured a displacement of 12.1 litres and delivered between 100 and 110 horsepower. By the middle of 1913, Anzani unveiled an expanded design that effectively doubled the cylinder count by arranging four rows of five cylinders each, resulting in a rated output of 200 horsepower and designated as the Anzani 20. This engine was presented at the Paris exhibition in 1913 and retained numerous design characteristics from its ten-cylinder predecessor. Constructed as an air-cooled unit, its cylinders were made from cast iron with built-in cooling fins. Both pistons and piston rings were also precision-machined from cast iron. The flat cylinder heads incorporated conical valve seats for both intake and exhaust valves, which were nickel steel poppet types. While early versions retained Anzani’s automatic atmospheric inlet valves, the exhaust valves were actuated by push-rods and rocker arms.
The crankcase was fabricated from aluminium and consisted of three bolted components: a central drum flanked by two end plates. Cylinders were secured through long bolts passing entirely through the crankcase. Due to the alignment requirements for big end bearings on the crankshaft, significant overlap occurred between adjacent cylinder rows. The hollow crankshaft, made of nickel steel, was supported by ball bearings and featured two crankpins positioned 180 degrees apart; each served ten cylinders located either at the front or rear. Lubrication was managed by two oil pumps delivering oil via internal passages in the crankshaft, which was then dispersed by centrifugal force. The engine incorporated two separate crankcase mixing chambers, each supplied by its own carburettor and intake manifold situated on opposite sides. Each section operated with an independent magneto spinning at 3,000 revolutions per minute. The arrangement of inlet manifolds placed exhaust valves near the engine’s centerline, allowing exhaust gases to exit through short Y-shaped pipes.
Applications
Bibliography
- E. Charles Vivian A History of Aeronautics (1920) https://web.archive.org/web/20111007205336/http://www.daytonhistorybooks.com/page/page/3260348.htm