Pratt & Whitney Hornet Aviation Models
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The Pratt & Whitney R-1690 Hornet.
In the mid 1930s, Pratt & Whitney produced five basic engines:
The single-row   Wasp Junior.
The single-row   Wasp.
The single-row   Hornet.
The double-row Twin Wasp.
The double-row Twin Wasp Junior.
    The Pratt & Whitney Hornet was a 9 cylinder, single-row, air-cooled radial engine. Horsepower ranged from 525 hp to 1,050 hp depending on the model and configuration. It was produced in two ranges:
The R-1690 Hornet A.
The R-1860 Hornet B.
    The series began with the R-1690 Hornet A in 1926 following production of the air-cooled R-1340 Wasp. It was enlarged in 1929 as the R-1860 Hornet B, but it was not a commercial success. The Hornet competed with its own Pratt & Whitney R-1830 Twin Wasp and the Wright Cyclone R-1820. Even though the Hornet was cheaper and simpler than the Twin Wasp, the Twin Wasp was a much more powerful engine and the Hornet's larger diameter was its main drawback. In the end, the Twin Wasp became a more sought after engine and the Hornet was dropped from production. 1

    Production was a modest 2,944 engines produced from 1926 to 1942 and it was used in a range of aircraft that included the Boeing B-9 and Boeing Model 299. By 1934, the Sikorsky S-42 was using four Hornets rated at 750 hp each.2 The Hornet was also built under license in Italy as the Fiat A.59 and in Germany as the BMW 132 which powered the Junkers Ju-52.3

Pratt & Whitney Hornet
Displacement: 1,690 cu. in. (27.7 liters) 1,860 cu. in. (30.5 liters)
Date: 1926 1929
Cylinders: 9 9
Configuration: Single-row, air-cooled radial Single-row, air-cooled radial
Horsepower: 525 hp (392 kW) 575 hp (429 kW)
RPM: 1,900 1,950
Bore and Stroke: 6.1 in. (156 mm) X
6.4 in. (162 mm)
6.3 in. (171 mm) X
6.8 in. (171 mm)
Diameter: 54.41 inches (1,382 mm) 54.41 inches (1,382 mm)
Weight: 800 lbs. (362 kg) 860 lbs. (390 kg)


1. Herschel Smith. A History of Aircraft Piston Engines. Manhattan, Kansas: Sunflower University Press, 1993. 107.
2. The Pratt & Whitney Aircraft Story. Pratt & Whitney: 1950. 77.
3. Herschel Smith. 134-136.

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© Larry Dwyer. The Aviation History On-Line Museum. All rights reserved.
Created January 19, 2013. Updated October 12, 2013.