Irwin Meteor Model 72, X-4 Radial Engine

Type: Reciprocating, radial, 4 cylinders, x-configuration; 2-stroke cycle, air-cooled

Power rating: 14.9 kW (20 hp) at 2,000 rpm

Displacement: 1.18 L (72 cu. in.)

Bore and Stroke: 73 mm (2.875 in.) x 70 mm (2.75 in.)

Weight: 27 kg (60 lb)

Beginning around 1922, J.F. Irwin’s Irwin Aircraft Company of Watsonville, California designed and provided blueprints for small, single seat sport aircraft which were supposedly simple enough for enthusiastic amateurs to build. In 1925, it introduced its Meteormotor. In 1926, it was improved by using copper instead of iron for cylinder cooling fins. Although classified as a radial, it was actually two opposed twins at ninety degrees to each other. This engine powered the Irwin M-T-2 and C-C-1 aircraft.