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Pratt & Whitney R-1340 Wasp


 The first Pratt & Whitney Wasp


The Pratt & Whitney R-1340 Wasp was a radial aircraft engine that was widely used in American aircraft from the 1920s onward. It was the Pratt & Whitney aircraft companys first engine, and the first of the famed Wasp series. It was a single-row, nine-cylinder, air-cooled, radial design, and displaced 1,344 cubic inches (22 L); bore and stroke were both 5.75 in (146 mm).
The Wasp C featured a solid master connecting rod and two piece crankshaft. The master connecting rod has a solid instead of detachable cap big end allowing higher crank speeds. The single throw two-pice crankshaft is divided into a forward and rear section. The crankpin is integral with the forward section which transmits power to the propeller hub carried by it. The rear section telescopes into the crankpin and is carried completely through it. The two sections are united by a hrough bolt and kept in the proper angular relation by splines.
The main crankcase of forged aluminium is divided into two similar sections in the plane of the cylinder and united by nine through bolts between the cylinders as well as by the cylinder flanges.
All valve perating parts are enclosed. The rocker arms are supporte by ball bearngs and are ounted in the rocker housings which are part of the cylinder head. The push rods are enclosed by telescopic covers held in place by springs.
Pratt & Whitney Wasp A Serial Number 1, (R-1340), Radial 9 Engine at the National Air and Space Museum.
After taking delivery of the prototype Wright XF3W-1, the Navy installed the Pratt & Whitney Wasp number two. The Wright XF3W-1 was the first airplane to fly with a Pratt & Whitney Wasp engine.


Every Pratt & Whitney engine is provided with a General Electric rotary induction fan used to provide proper mixture distribution. With suitable gear ratio it is possible for certain specialised purposes to provide a reasonable amount of supercharging without additional weight or complication.
All the accessories are grouped at the rear of the engine protected by the cowling.
On geared engines a 2:1 propeller speed reduction is provided by a geared unit of patented Pratt & whiney design, weighing 775 lb.
First run on 29 December 1925, a total of 34,966 engines were produced.


R-1340-7: 450 hp (336 kW), 600 hp (447 kW)
R-1340-8: 425 hp (317 kW)
R-1340-9: 450 hp (336 kW), 525 hp (391 kW)
R-1340-16: 550 hp (410 kW)
R-1340-17: 525 hp (391 kW)
R-1340-19: 600 hp (447 kW)
R-1340-19F: 600 hp (447 kW)
R-1340-21G: 550 hp (410 kW)
R-1340-22: 550 hp (410 kW)
R-1340-23: 575 hp (429 kW)
R-1340-30: 550 hp (410 kW)
R-1340-31: 550 hp (410 kW)
R-1340-33: 600 hp (447 kW)
R-1340-48: 600 hp (447 kW)
R-1340-49: 600 hp (447 kW)
R-1340-AN1: 550 hp (410 kW), 600 hp (447 kW)
R-1340-AN2: 550 hp (410 kW), 3:2 geared prop shaft
R-1340-B: 450 hp (336 kW)
R-1340-D: 500 hp (373 kW)
R-1340-S1H1-G: 550 hp (410 kW), 600 (447 kW)
R-1340-S3H1: 600 hp (447 kW)


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Westland Whirlwind (helicopter)




Wasp A
Nine-cylinder radial direct-drive
Displacement: 1,343.8-cubic-inch / 22.021 lt
Compression ratio: 5.25:1
Power rating: 410 hp at 1,900 rpm at SL
Fuel: 58 octane gasoline
Length: 3 ft 6.63 in / 1.083 m
Diameter: 4 ft 3.44 in / 1.307 m
Weight: 745 lb / 338 kg


Wasp C
Type: 9 cylinder fixed radial, air cooled
Military Rating: 450 hp at 2100 rpm
Commercial Rating Direct: 420 hp at 2000 rpm
Commercial Rating Geared: 420 hp at 2100 rpm
Displacement: 1344
Compression ratio: 5.24-1
Bore: 5 3/4 in
Stroke: 5 3/4 in
Length: 42 9/16 in
Diameter: 51 1/2 in
Weight: 695 lb
Fuel consumption: not more than .55 lb/hp/hr
Oil consumption: not more than .035 lb/hp/hr
Lubrication: Pressure (gear pump) 75-100 lb
Ignition: Scintilla, dual
Carburation: Stromberg, 2 bbls
Starter: Eclipse
Spark plugs: B.G.
Price Series C: $7200
Price Series C.G: $8200


Type: Nine-cylinder single-row supercharged air-cooled radial engine
Bore: 5.75 in (146 mm)
Stroke: 5.75 in (146 mm)
Displacement: 1,344 in3 (22 L)
Diameter: 51.75 in (1.314 m)
Dry weight: 930 lb (422 kg)
Valvetrain: Two overhead valves per cylinder
Supercharger: Single-speed centrifugal type supercharger, 1:10 step-up
Fuel system: Two-barrel Stromberg carburetor
Fuel type: 91 octane rating gasoline
Cooling system: Air-cooled
Reduction gear: 3:2
Power output: 600 hp (447 kW) at 2,250 rpm at 6,200 ft (1,890 m)
Specific power: 0.45 hp/in³ (20.3 kW/L)
Compression ratio: 6:1
Power-to-weight ratio: 0.65 hp/lb (1.05 kW/kg)



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