Pratt & Whitney R-1690 Hornet
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|Pratt & Whitney Hornet, at the Deutsches Museum, Munich.|
|National origin||United States|
|Manufacturer||Pratt & Whitney|
|First run||June 1926|
|Major applications||Lockheed Lodestar
|Developed into||Pratt & Whitney R-1860
The Pratt & Whitney R-1690 Hornet was a widely used aircraft engine. Developed by Pratt & Whitney, 2,944 were produced from 1926 through 1942. It first flew in 1927. It was a single-row, 9-cylinder air-cooled radial design. Displacement was 1,690 cubic inches (27.7 L). It was built under licence in Italy as the Fiat A.59. In Germany, the BMW 132 was a developed version of this engine. The R-1860 Hornet B was an enlarged version produced from 1929.
- 525 hp (392 kW)
- 525 hp (392 kW)
- 775 hp (578 kW)
- 625 hp (466 kW)
- 700 hp (522 kW)
- 750 hp (559 kW)
- 750 hp (559 kW)
- 850 hp (634 kW)
- 1,050 hp (780 kW)
- Fiat A.59 R.
- Licence built in Italy with reduction gearing.
- Fiat A.59 R.C.
- Licence built in Italy with reduction gearing and supercharger.
- BMW Hornet
- Licence production of the Hornet in Germany, independently developed as the BMW 132.
- Bach Air Yacht
- Bellanca 31-40
- Boeing 80
- Boeing Model 95
- Boeing Model 299
- Burnelli UB-14
- Douglas O-38
- Focke-Wulf Fw 200 V1
- Junkers Ju-52
- Junkers Ju 86
- Junkers W 34
- Keystone B-3
- Lockheed Model 14 Super Electra (L-14H)
- Lockheed Lodestar (C-56A, C-56B, C-56C, C-56D, C-56E, C-59/Mk 1a)
- Martin XB-14
- Vought O2U Corsair
- Sikorsky S-40A
- Sikorsky S-42
- Sikorsky S-43
- Wedell-Williams Model 44
Engines on display
- There is a R-1690 on display at the New England Air Museum, Bradley International Airport, Windsor Locks, CT.
Specifications (R-1690 SIE-G)
Data from 
- Type: Nine-cylinder single-row supercharged air-cooled radial engine
- Bore: 6 1⁄8 in (155.6 mm)
- Stroke: 6 3⁄8 in (161.9 mm)
- Displacement: 1,690.5 in³ (27.7 l)
- Length: 50.98 in (1,295 mm)
- Diameter: 54.41 in (1,382 mm)
- Dry weight: 1,014 lb (460 kg)
- Valvetrain: Pushrod-actuated
- Supercharger: Single-speed centrifugal type supercharger, 12.0:1 gear ratio
- Fuel system: Two-barrel Stromberg carburetor
- Fuel type: 87 octane rating gasoline
- Cooling system: Air-cooled
- Reduction gear: Epicyclic gearing, 2:3
- Power output:
- 789 hp (589 kW) at 2,300 rpm for takeoff
- 740 hp (552 kW) at 2,250 rpm at 7,000 ft (2,135 m)
- Specific power: 0.47 hp/in³ (21.26 kW/l)
- Compression ratio: 6.0:1
- Specific fuel consumption: 0.6 lb/(hp•h) (362 g/(kW•h))
- Oil consumption: 0.42 oz/(hp•h) (16 g/(kW•h))
- Power-to-weight ratio: 0.78 hp/lb (1.28 kW/kg)
- Pratt & Whitney - R-1690 page Archived 2008-01-26 at the Wayback Machine. Retrieved: 25 October 2008
- http://neam.org/index.php?option=com_content&view=article&layout=edit&id=1129 "Pratt & Whitney R-1690 Hornet"
- Tsygulev (1939). Aviacionnye motory voennykh vozdushnykh sil inostrannykh gosudarstv (Авиационные моторы военных воздушных сил иностранных государств) (in Russian). Moscow: Gosudarstvennoe voennoe izdatelstvo Narkomata Oborony Soyuza SSR. Archived from the original on 2009-03-24.
- Gunston, Bill (2006). World Encyclopedia of Aero Engines, 5th Edition. Phoenix Mill, Gloucestershire, England, UK: Sutton Publishing Limited. ISBN 0-7509-4479-X.
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