Pratt & Whitney R-1535 Twin Wasp Junior

R-1535 Twin Wasp Junior
	Pratt & Whitney Twin Wasp Junior, at the National Museum of Naval Aviation, Pensacola, Florida
Type	Radial engine
National origin	United States
Manufacturer	Pratt & Whitney
First run	1932
Major applications	Bristol Bolingbroke; Curtiss SBC-3 Helldiver; Hughes H-1 Racer; Vought SB2U Vindicator; ;
Developed from	Pratt & Whitney R-985 Wasp Junior

The Pratt & Whitney R-1535 Twin Wasp Junior is an American aircraft engine developed in the 1930s. The engine was introduced in 1932 as a 14-cylinder version of the 9-cylinder R-985, and was a two-row, air-cooled radial design. Displacement was 1,535 cu in (25.2 L); bore and stroke were both 5 3⁄16 in (132 mm).^[1]

Variants

R-1535-11 - 750 hp (560 kW)
R-1535-13 - 750 hp (560 kW), 825 hp (615 kW)
R-1535-44 - 625 hp (466 kW)
R-1535-72 - 650 hp (480 kW)
R-1535-94 - 825 hp (615 kW)
R-1535-96 - 825 hp (615 kW)
R-1535-98 - 700 hp (520 kW)
R-1535-SB4-G - 825 hp (615 kW)

Applications

Bellanca 28-70
Boeing XF6B
Breguet 695
Bristol Fairchild Bolingbroke (Canadian licence-built version of the Blenheim)
Canadian Car and Foundry FDB-1
Consolidated XB2Y
Curtiss SBC-3 Helldiver
Douglas O-46
Fokker G.I (G.I The Wasp)
Fokker D.XXI (Finnish licence-built series 4 and 5)
Great Lakes BG
Grumman F2F
Grumman F3F-1
Grumman XJF-1 Duck (prototype only)
Grumman XSBF
Grumman XSF-2
Hughes H-1 Racer
Miles Master
Northrop A-17
Northrop BT
Northrop XFT-2
Vought SBU Corsair
Vought SB2U Vindicator
Vought V-141
Vought XF3U
Vought XO4U-2

Engines on display

There is a R-1535-96 on display at the New England Air Museum, Bradley International Airport, Windsor Locks, CT.^[2]
There is an R-1535 on display at the San Diego Air and Space Museum. It is now being installed in the museum's Hughes H-1 Racer reproduction project.^{[citation needed]}

Specifications (R-1535-SB4-G)

Data from ^[3]

General characteristics

Type: Fourteen-cylinder two-row supercharged air-cooled radial engine
Bore: 5 3⁄16 in (131.8 mm)
Stroke: 5 3⁄16 in (131.8 mm)
Displacement: 1,534.9 cu in (25.153 L)
Length: 53.27 in (1,353 mm)
Diameter: 44.13 in (1,121 mm)
Dry weight: 1,087 lb (493 kg)

Components

Valvetrain: Two overhead valves per cylinder
Supercharger: Single-speed centrifugal type supercharger, 11:1 step-up
Fuel system: Two-barrel Stromberg carburetor
Fuel type: 87 octane rating gasoline
Cooling system: Air-cooled
Reduction gear: Epicyclic gearing, 0.75:1

Performance

Power output: 825 hp (615 kW) at 2,625 rpm for takeoff
Specific power: 0.54 hp/cu in (24.57 kW/L)
Compression ratio: 6.75:1
Specific fuel consumption: 0.49 lb/(hp•h) (295 g/(kW•h))
Oil consumption: 0.39 oz/(hp•h) (15 g/(kW•h))
Power-to-weight ratio: 0.76 hp/lb (1.25 kW/kg)

References

Notes

^ "P&W Twin Wasp Junior(R-1535)". www.enginehistory.org. Retrieved 2024-09-23.
^ "Pratt & Whitney R-1535-96 Twin Wasp Junior"
^ 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.

Bibliography

Gunston, Bill. World Encyclopedia of Aero Engines: From the Pioneers to the Present Day. 5th edition, Stroud, UK: Sutton, 2006.ISBN 0-7509-4479-X
White, Graham. Allied Aircraft Piston Engines of World War II: History and Development of Frontline Aircraft Piston Engines Produced by Great Britain and the United States During World War II. Warrendale, Pennsylvania: SAE International, 1995. ISBN 1-56091-655-9

External links

[1] "P&W Twin Wasp Junior(R-1535)". www.enginehistory.org. Retrieved 2024-09-23.

[2] "Pratt & Whitney R-1535-96 Twin Wasp Junior"

[tsygulev-3] 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.

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