I wrote this as a starter for a Gloster F5/34 naval fighter story but havent been able to construct a decent timeline.
In 1932 Armstrong Siddeley released its latest engine the 32.7 litre (1995ci) 14 cylinder Tiger a 700hp 2 speed supercharged engine perfect for high performance aircraft. It was a development of the 14 cylinder Armstrong Siddeley Big Cat series of engines that went back as far as the WWI RAF8 engine.
Unfortunately the big Cat engines had always had a problem with vibration which the AS engineers had tried to stop by increasing the strength of the crankcase and the bearings. These workarounds had so far ameliorated the problem but not made it go away and whilst the problems had been bearable in a 450hp engine the new faster revving 750hp plus Tiger had reached the limits of the 2 bearing crank design. The engine had the potential to give more power but increasing revs past 2000rpm just resulted in a big bang and a crank failure.
In 1935 Tommy Sopwith owner of Hawker Aircraft bought Armstrong Siddeley and Gloster Aircraft and he decided that stretching the old design was no longer possible or sensible and a clean sheet design was needed for a new engine. The Air Ministry was contacted to see if a new engine with a potential of 1000hp would be suitable for future aircraft designs, the Air Ministry gave non committal answer saying it would be evaluated for new bomber designs. This was enough for the Hawker Siddeley board to give the go ahead.
A new design incorporating all the latest technology and the all important 3 bearing crankshaft was laid out and by early 1936 the new engine called the Cougar was on the test bed.
The Tiger had managed to limp to 800hp at 2,100rpm by this time but the new Cougar romped to 2,700 rpm with no vibration problems. It was decided immediately to cancel all future development of the Tiger and concentrate on the new Cougar.
Work started on a flying version of the engine and a Hawker Hart biplane bomber was obtained to be the test aircraft. The hart with a 600hp Kestrel was good for 185 mph but with the new Cougar MkI in a neat full chord cowling rated at 975hp it managed to peak at 222mph.The Air Ministry was impressed by the new engine and financed the building of a new shadow factory to build it but still thought of it as a Bomber engine specifying it as the engine for the AW Whitley Night Bomber.
Glosters, Bristol and Vickers had all built prototypes for a new fighter to specification F5/34 but Bristol and Vickers were stuck with the comparatively weak Bristol Mercury. Glosters on the other hand fitted their aircraft with a AS Cougar MkX producing 1075hp on 87 Octane. The longer heavier engine caused some stability problems but a quick fix of a tail fillet solved the problems. In competition with the Hawker Hurricane MkI fitted with a RR Merlin MkII producing 1030hp showed the Gloster to be 5mph slower but with a climb to 20,000ft a whole minute quicker.
The RAF was impressed with the new Gloster fighter but preferred not to adopt an air cooled engine for home use. However the Admiralty heard of the new fighter and engine combination and requested a trial of the fighter loaded with ballast to replicate a navalised version. The Gloster F5/34 now called the Buzzard proved to be a fine handling aircraft but needed bigger flaps to slow down the landing speed for carriers.
In October 1939 the Royal Navy ordered 150 Buzzard MkIs equipped with an AS Cougar MkXII producing 1180hp and Fowler flaps but no folding wings. A 2nd order for 150 folding wing Buzzard MkIIs with a AS Cougar MkXV producing the same power but capable of using +12psi boost to give 1340hp for 5 minutes below 12,000ft was placed at the same time to be started as soon as the order for MkIs was finished.
Cougar 14-cylinder supercharged two-row air-cooled radial engine
Cougar MkVI 1200hp fitted with Claudel Hobson Carb, DeHavilland Constant speed propellor and 2 speed supercharger. Fitted to Whitley MkV
Cougar MkXXI 1400hp fitted with Claudel Hobson carb Rotol propellor and 2 speed supercharger. Fitted to Wellington MkX Halifax MkII and Short Sunderland MkIII.
Cougar MkX 1180hp fitted with Claudel Hobson carb, DeHavilland constant speed prop and 2 speed supercharger. Fitted to Buzzard MkI
Cougar MkXV 1180hp fitted with Bendix Stromberg pressure carb and 2 speed carb. Fitted to the Buzzard MkII
Cougar MkXXX 1600hp Fitted with Bendix carb, Rotol prop and single speed low level supercharger. Fitted to Fairey Barracuda MkII and Hawker Hurricane MkIV.
Cougar MkXXI 1600hp fitted with Bendix carb, DeHavilland prop and 2 speed 2 stage carb, Fitted to Buzzard MkIII and Beaufighter MkV.
In 1932 Armstrong Siddeley released its latest engine the 32.7 litre (1995ci) 14 cylinder Tiger a 700hp 2 speed supercharged engine perfect for high performance aircraft. It was a development of the 14 cylinder Armstrong Siddeley Big Cat series of engines that went back as far as the WWI RAF8 engine.
Unfortunately the big Cat engines had always had a problem with vibration which the AS engineers had tried to stop by increasing the strength of the crankcase and the bearings. These workarounds had so far ameliorated the problem but not made it go away and whilst the problems had been bearable in a 450hp engine the new faster revving 750hp plus Tiger had reached the limits of the 2 bearing crank design. The engine had the potential to give more power but increasing revs past 2000rpm just resulted in a big bang and a crank failure.
In 1935 Tommy Sopwith owner of Hawker Aircraft bought Armstrong Siddeley and Gloster Aircraft and he decided that stretching the old design was no longer possible or sensible and a clean sheet design was needed for a new engine. The Air Ministry was contacted to see if a new engine with a potential of 1000hp would be suitable for future aircraft designs, the Air Ministry gave non committal answer saying it would be evaluated for new bomber designs. This was enough for the Hawker Siddeley board to give the go ahead.
A new design incorporating all the latest technology and the all important 3 bearing crankshaft was laid out and by early 1936 the new engine called the Cougar was on the test bed.
The Tiger had managed to limp to 800hp at 2,100rpm by this time but the new Cougar romped to 2,700 rpm with no vibration problems. It was decided immediately to cancel all future development of the Tiger and concentrate on the new Cougar.
Work started on a flying version of the engine and a Hawker Hart biplane bomber was obtained to be the test aircraft. The hart with a 600hp Kestrel was good for 185 mph but with the new Cougar MkI in a neat full chord cowling rated at 975hp it managed to peak at 222mph.The Air Ministry was impressed by the new engine and financed the building of a new shadow factory to build it but still thought of it as a Bomber engine specifying it as the engine for the AW Whitley Night Bomber.
Glosters, Bristol and Vickers had all built prototypes for a new fighter to specification F5/34 but Bristol and Vickers were stuck with the comparatively weak Bristol Mercury. Glosters on the other hand fitted their aircraft with a AS Cougar MkX producing 1075hp on 87 Octane. The longer heavier engine caused some stability problems but a quick fix of a tail fillet solved the problems. In competition with the Hawker Hurricane MkI fitted with a RR Merlin MkII producing 1030hp showed the Gloster to be 5mph slower but with a climb to 20,000ft a whole minute quicker.
The RAF was impressed with the new Gloster fighter but preferred not to adopt an air cooled engine for home use. However the Admiralty heard of the new fighter and engine combination and requested a trial of the fighter loaded with ballast to replicate a navalised version. The Gloster F5/34 now called the Buzzard proved to be a fine handling aircraft but needed bigger flaps to slow down the landing speed for carriers.
In October 1939 the Royal Navy ordered 150 Buzzard MkIs equipped with an AS Cougar MkXII producing 1180hp and Fowler flaps but no folding wings. A 2nd order for 150 folding wing Buzzard MkIIs with a AS Cougar MkXV producing the same power but capable of using +12psi boost to give 1340hp for 5 minutes below 12,000ft was placed at the same time to be started as soon as the order for MkIs was finished.
Cougar 14-cylinder supercharged two-row air-cooled radial engine
- Bore: 5.5 in (139.7 mm)
- Stroke: 6.0 in (152.4 mm)
- Displacement: 1,995 in³ (32.7 l)
- Length: 64.6 in (1,641 mm)
- Diameter: 50.8 in (1,290 mm)
Cougar MkVI 1200hp fitted with Claudel Hobson Carb, DeHavilland Constant speed propellor and 2 speed supercharger. Fitted to Whitley MkV
Cougar MkXXI 1400hp fitted with Claudel Hobson carb Rotol propellor and 2 speed supercharger. Fitted to Wellington MkX Halifax MkII and Short Sunderland MkIII.
Cougar MkX 1180hp fitted with Claudel Hobson carb, DeHavilland constant speed prop and 2 speed supercharger. Fitted to Buzzard MkI
Cougar MkXV 1180hp fitted with Bendix Stromberg pressure carb and 2 speed carb. Fitted to the Buzzard MkII
Cougar MkXXX 1600hp Fitted with Bendix carb, Rotol prop and single speed low level supercharger. Fitted to Fairey Barracuda MkII and Hawker Hurricane MkIV.
Cougar MkXXI 1600hp fitted with Bendix carb, DeHavilland prop and 2 speed 2 stage carb, Fitted to Buzzard MkIII and Beaufighter MkV.
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