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Pobjoy Niagara
Pobjoy Cataract
Pobjoy Cascade

 

Pobjoy-Niag
Pobjoy Niagara

 

The Pobjoy Niagara is a British seven-cylinder, air-cooled, radial, aero-engine first produced in 1934. The design ran at higher speeds than conventional engines, and used reduction gearing to lower the speed of the propeller. This led to a noticeable off-centre mounting for the propeller. The Niagara was a popular engine for light and experimental aircraft, well regarded due to their small diameter, smooth operation, low noise and innovative engineering.

 

Variants:
Niagara I
Bore/stroke 77 x 87 mm (3.03 x 3.43 in)
Swept volume 2,835 cc (173 cu in)
Compression 6.25:1
Gearing 0.47:1
Normal continuous power 84 hp (63 kW) at 3,200 rpm at sea level.
 
Niagara II
Bore/stroke 77 x 87 mm (3.03x3.43 in)
Swept volume 2,835 cc (173 cu in)
Compression 6.0:1
Gearing 0.39:1
Normal continuous power 84 hp (63 kW) at 3,200 rpm at sea level.
 
Niagara III
Bore/stroke 77 x 87 mm (3.03x3.43 in)
Swept volume 2,835 cc (173 cu in)
Gearing 0.47:1
Normal continuous power 88 hp (66 kW) at 3,300 rpm at sea level.
 
Niagara IV
Similar to Niagara III but with a higher operating rpm.
Normal continuous power 98 hp (73 kW) at 3,500 rpm at sea level.
 
Niagara V
Larger version of the basic Niagara.
Bore/stroke 81 x 87 mm (3.19 x 3.43 in)
Swept volume 3,138 cc (192.5 cu in).
Compression 8.0:1
Gearing 0.47:1
Normal continuous power 125 hp (93 kW) at 4,000 rpm at sea level.
 
Cataract I-III
De-rated, uncowled versions of Niagara I-III with simple inter-cylinder baffles for cooling and trickle-down lubrication for lower exhaust rockers.
Compression 5.7:1
Gearing 0.47:1

Cascade
Direct drive version of Cataract I.
Normal continuous power 66 hp (49 kW) at 2,100 rpm.
 
Applications:
Niagara -  
Aeroput MMS-3
Airspeed Fleet Shadower
CLW Curlew
Comper Kite
Comper Swift
General Aircraft Monospar ST-25
General Aircraft Fleet Shadower
Lambach HL.I
Pobjoy Pirate
Saro Shrimp
Shapley Kittiwake
Short Scion Senior
Short Scion
Short Stirling (half scale prototype)
Spartan Clipper

Cataract -
British Klemm Swallow
Hafner A.R.III Gyroplane
Hendy Hobo

Cascade -
Autogiro AC-35

 

Specifications:
Pobjoy Niagara IV
Type: 7-cylinder, air-cooled, radial engine
Bore: 3.03 in (77 mm)
Stroke: 3.43 in (87 mm)
Displacement: 173 cu in (2.8 lt)  
Diameter: 26.5 in (673 mm)
Dry weight: 130 lb (59 kg)
Valvetrain: 1 inlet and 1 exhaust valve per cylinder
Fuel system: 1 Claudel-Hobson carburettor
Fuel type: 70 octane
Cooling system: Air-cooled
Power output: 98 hp at 3,625 rpm max at sea level
Compression ratio: 6:1
Power-to-weight ratio: 0.75 hp/lb

 

 

 

 

 


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