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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,[1] well regarded due to its small diameter, smooth operation, low noise and innovative engineering.

Niagara
Pobjoy Niagara on display at the Science Museum, London
Type	Piston radial aero engine
Manufacturer	Pobjoy Airmotors
First run	1934

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.[2]

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.[2]

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.[2]

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.[2]

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 (191.5 cu in). Compression 8.0:1, gearing 0.47:1. Normal continuous power 125 hp (93 kW) at 4,000 rpm at sea level.[2][3]

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.[2][3][4]

Cascade

Direct drive version of Cataract I. Normal continuous power 66 hp (49 kW) at 2,100 rpm.[4]

Applications

Niagara

• Aeroput MMS-3
• Airspeed Fleet Shadower
• CLW Curlew
• Comper Kite
• Comper Swift
• General Aircraft Monospar ST-25
• General Aircraft Fleet Shadower
• Gribovsky G-25
• Lambach HL.I
• Moss M.A.1
• Pobjoy Pirate
• Saro Shrimp
• Shapley Kittiwake
• Short Scion Senior
• Short Scion
• Short S.31 (half scale Stirling)
• Spartan Clipper
• Westland CL.20

Cataract

• British Klemm Swallow
• Hafner A.R.III Gyroplane
• Hendy Hobo
• Pitcairn PA-22

Cascade

• Autogiro AC-35

Survivors

A Pobjoy Niagara powered Comper Swift G-ACTF that is owned and operated by The Shuttleworth Collection, Old Warden remains airworthy in 2017 and displays to the public at home airshows during the flying season.[5]

Engines on display

A preserved Pobjoy Niagara engine is on public display at the Science Museum (London).

Specifications (Pobjoy Niagara IV)

Data from Lumsden.[2]

General characteristics

• 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 L)
• Diameter: 26.5 in (673 mm)
• Dry weight: 130 lb (59 kg)

Components

• Valvetrain: 1 inlet and 1 exhaust valve per cylinder
• Fuel system: 1 Claudel-Hobson carburettor
• Fuel type: 70 octane
• Cooling system: Air-cooled

Performance

• Power output: 98 hp at 3,625 rpm max at sea level
• Compression ratio: 6:1
• Power-to-weight ratio: 0.75 hp/lb

See also

Related development

• Pobjoy R

Comparable engines

• Rotec R2800
• Warner Scarab

Related lists

• List of aircraft engines

References

Notes

Bibliography

External links

• Pobjoy Niagara at oldengine.org
• "A New Pobjoy Engine" - article in Flight

На других языках

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[de] Pobjoy Niagara

Der Pobjoy Niagara war ein britischer luftgekühlter 7-Zylinder-Sternmotor. Der Motor wurde ab 1934 vom Unternehmen Pobjoy Airmotors hergestellt und zeichnete sich durch seine für einen Sternmotor ungewöhnliche Gestaltung aus. Aufgrund des in das Motorgehäuse eingebauten Untersetzungsgetriebes trat die Motorwelle außermittig aus dem Motor aus. Der Niagara war ein häufig in Leicht- und Versuchsflugzeugen eingesetzter Motor. Die gesamte Reihe der von Pobjoy Motors produzierten Triebwerke bestand aus 7-Zylinder-Sternmotoren mit sehr kompakten Abmessungen und sehr hohen Drehzahlen. Pobjoy Airmotors genoss für ihre Motoren aufgrund deren geringen Abmessungen, der niedrigen Betriebskosten, des niedrigen Geräuschpegels sowie für ihre originellen technischen Lösungen ein hohes Ansehen.

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- [en] Pobjoy Niagara

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[it] Pobjoy Niagara

Il Pobjoy Niagara era un motore aeronautico radiale 7 cilindri a singola stella raffreddato ad aria, introdotto dall'azienda britannica Pobjoy Airmotors & Aircraft, Ltd. nel 1934.

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