Alfa Romeo 128 R.C.21, Radial 9 Engine

Type: Reciprocating, 9 cylinders, geared, supercharged, radial, air-cooled

Power rating: 708 kW (950 hp) at 2,300 rpm

Displacement: 28.6 L (1,746 cu in.)

Bore and Stroke: 146 mm (5.75 in.) x 190 mm (7.50 in.)

Weight: 516.2 kg (1,138 lb)

Societa Anonima Alfa Romeo of Milan, Italy, manufacturer of the famous Alfa Romeo automobiles, entered the aircraft engine business in 1917, and acquired a license for the Roy Fedden designed Bristol Jupiter in 1925 and, later in 1931, licenses for the Bristol Mercury and Pegasus engines. These actions were largely directed by the Italian government following World War I as a means of regenerating Italian aviation. A Jupiter license was also acquired by the well-known French manufacturer Gnome-Rhone, indicating the connected international development of aircraft engine technology.

From the Pegasus engine, the company developed the Alfa 125 R.C.35 and 125 R.C.10. From the Alfa 125 R.C., in 1936, Alfa-Romeo developed the Alfa R.C.34 and 126 R.C.10, and later the Alfa 128 R.C.21. This was a family of nine-cylinder, air-cooled, radial engines with 4 valves per cylinder whose performance was progressively uprated.