The Whirlwind was a twin-engine, heavy fighter developed by Westland Aircraft, not to be confused by the Westland Whirlwind helicopter of many years later. It was developed in the 1930s as a heavy fighter and potential bomber escort. As a result of German resurgence and experience in the Spanish Civil War, it began to dawn on the planners of air power doctrine that the bomber might not always get through.
When it first flew in 1938, the Whirlwind was the fastest and the most heavily armed combat aircraft in the world. Unfortunately it suffered with development problems with its Rolls Royce Peregrine engines, which delayed the project at a crucial time. War with Germany was seen as inevitable and limited production was required for proven, single-seat fighters such as the Hurricane and Spitfire. The aircraft was only produced in sufficient numbers to equip three RAF Squadrons and it was withdrawn from service in 1943.
From the mid-1930s aircraft designers theorised that increased attack speeds meant that fighter pilots would only have a limited time on target, which might be insufficient to fire enough rifle-calibre rounds to destroy a target. The designers of the Hurricane and Spitfire mitigated this by installing eight Browning machine-guns in each fighter. Even so, in the early dogfights of 1940, it took long bursts to bring down a target, especially if the fighter pilot was inexperienced and opened fire at too great a distance. The French had developed the 20mm Hispano-Suiza HS.404 cannon, which fired explosive ammunition. Aircraft designers began to look into aircraft designs that could carry four of these cannons. Single engine fighters because of their limited range were seen as defensive or interceptor aircraft, whereas the cannon-armed fighter would be larger, carry more fuel and could be used in an offensive role.
In the two photographs below, the difference between rifle calibre bullets and explosive cannon shells can clearly be seen. The Heinkel 111 has been riddled with bullets before it was brought down. The Halifax was hit once from underneath by a Schräge Musik equipped night fight and was lucky to make it home.
The RAF Air Staff urgently drew up Air Ministry Specification F37/35, calling for an experimental single-seat day fighter aircraft and possible night fighter armed with four cannons. The top speed had to be at least 40 mph greater than that of contemporary bombers – at least 330 mph at 15,000 ft. It was a complex specification and Boulton Paul and Bristol tendered single-seat designs with twin engines. Hawker and Supermarine tendered single-engine designs. The Westland P.9 had two Rolls Royce Kestrel engines with wing- mounted cannons and a twin tail design.
The designs were considered in 1938 and there was concern that two engines would render the aircraft less manoeuvrable than a single-engine fighter and that the recoil of the cannons in the wings would result in inaccurate fire. Therefore the cannons should be concentrated in the nose. Because of vested interests and the development of the Spitfire, the Supermarine design would have been the preferred option, but realistically, neither they nor Hawker were in a position to deliver the specification’ especially with nose-mounted guns. Westland had less production programmes and was more advanced with the project, so the Supermarine and Hawker concepts were cancelled and Westland became the bidder of choice.
Westland’s design team was led by W.E.W Petter who would go on to design the English Electric Canberra, Lightning and the Folland Gnat. The Whirlwind would have state-of-the-art technology, a monocoque, tubular fuselage with a high T-tail empennage to move the elevators up, out of the turbulence caused by the Fowler Flaps. The engines were Rolls Royce Peregrines, a derivative of the Kestrel and were cooled by radiators set in the leading edge of the wing, inboard from the engines to reduce drag. The aircraft had an all metal stress-skinned covering and was aerodynamically very clean. The pilot sat under one of the first bubble canopies, which gave an unrestricted view and excellent field of vision, except for directly under the nose, which mounted the four 20mm cannons. The 20mm Hispano-Suiza HS.404 had a rate of fire of 700 rounds per minute, and a two second burst could lay down 93 rounds of exploding cannon shells. For its day, the Whirlwind should have been an awesome aircraft.
The Whirlwind was only slightly larger than the Hurricane and its twin 885 hp Peregrine engines powered it to over 360mph in level flight, the same as the Spitfire Mk I, but it had a short range of under 300 miles, which made it of limited value as an escort fighter. The first deliveries of the Peregrine engines were not delivered to Westland until January 1940. The Whirlwind was a victim of timing and cold, hard necessity. The delay in engine delivery, caused by Rolls Royce concentrating on the Merlin, delayed introduction into front line service. By late 1940, Spitfires and Hurricanes successfully trialled the fitting of cannons and escort fighters became unnecessary when Bomber Command began operating at night, due to high losses. Fighter Command were looking for a larger aircraft that could be fitted with the early large and cumbersome Airborne Interception Radar. The Bristol Blenheim and later the Bristol Beaufighter fitted this role perfectly.
Full-scale production was dependent on the test programme, but the Whirlwind needed more than 250 modifications, which held up the initial production order for 200 aircraft. Delivery to the front-line squadrons was scheduled to begin in September 1940 and the second tranche of 600 that was due to be built at the Castle Bromwich works was dropped in favour of Spitfire production. Production was halted in January 1942. Rolls Royce were concentrating engine manufacture on the Merlin and the much-troubled Vulture engine. The Vulture caused endless problems with overheating and fires in the Avro Manchester bomber. A redesign of the aircraft resulted in the superlative Lancaster bomber, but development time and effort was lost on the Vulture, which could have been used to improve the Peregrine engine; hindsight is a wonderful thing, especially in wartime. However, it should be noted that there was absolutely nothing wrong with the Peregrine engine, it just lacked the additional horsepower and high-altitude performance that routine development and the fitting of a supercharger could have provided.
Westland had designed and built an outstanding fighter, but the design was tied to the Peregrine engine, and it would have taken an extensive redesign for the aircraft to be fitted with larger Merlin engines. And fitting Merlins wasn’t always the panacea as the Fairy Battle, Vickers Wellington and Handley Page Halifax proved. Petter campaigned for the Whirlwind Mk II which would have been powered by a more powerful 1,010 hp Peregrine fitted with a high altitude supercharger and using 100 octane fuel. But it was the bottom line that did for the aircraft. The construction of each Whirlwind consumed three times the material and man hours of a Spitfire.
The aircrew who flew the Whirlwind considered themselves to be a privileged elite. Sergeant Buckwell of 263 Squadron concluded:
… In retrospect the lesson of the Whirlwind is clear… A radical aircraft requires either prolonged development or widespread service to exploit its concept and eliminate its weaknesses. Too often in World War II, such aircraft suffered accelerated development or limited service, with the result that teething difficulties came to be regarded as permanent limitations.”
The pilots did criticise the aircraft’s high landing speed and its lack of power at higher altitude. As a result the Whirlwind was used in the low-level ground attack, specifically the highly dicey attacks on German airfields, marshalling yards and railway locomotives. It was a stable gun platform and the concentrated cannons could rip a locomotive to pieces on a single pass. It was also used against E-boats and coastal shipping in the Channel. At lower altitude the Whirlwind could hold its own against the Messerschmitt BF 109 E and F. Being twin engined it gave their pilots a better chance of making it home across the Channel if the aircraft were damaged.
The first squadron to be equipped with the Whirlwind was 263 Squadron based at Grangemouth in Scotland, after being almost wiped out during the Norwegian Campaign, but deliveries were slow, there being only five by August 1940. Despite the need for fighters down south during the Battle of Britain, Dowding CinC Fighter Command stated that 263 could not be deployed south because “there was no room for passengers,” in that part of the country.
Number 263 Squadron moved south to Exeter and was declared fully operational in December 1940, with the Whirlwind on 7 December 1940. Initial operations consisted of convoy patrols and anti E-boat missions. The Whirlwind’s first confirmed kill occurred on 8 February 1941, when an Arado 196 floatplane was shot down; the Whirlwind responsible also crashed into the sea and the pilot was killed. From then on the squadron was to have considerable success with the Whirlwind while flying against enemy Junkers 88s, Dornier Do 217s, Messerschmitt Bf 109s and Focke-Wulf 190s.
263 Squadron also occasionally carried out day bomber escort missions with the Whirlwinds. They formed part of the escort of 54 Blenheims on a low-level raid against power stations near Cologne on 12 August 1941; owing to the relatively short range of the escorts, including the Whirlwinds, the fighters turned back near Antwerp, with the bombers continuing on without escort. Ten Blenheims were lost.
The Whirlwinds of 263 and 137 Squadrons mostly flew low-level attack sorties across into France, called Rhubarbs against ground targets and Roadstead against shipping. On 6th August 1941, four Whirlwinds on an anti-shipping strike were intercepted by a large formation of BF 109s. The Whirlwinds claimed three of the German aircraft for no loss. In the summer of 1942, both 263 and 137 squadrons were fitted with racks to carry two 250 or 500 lb bombs, and nicknamed the Whirlybomber. These undertook low-level cross-channel Rhubarb sweeps, attacking locomotives, bridges, shipping and other targets.
No 137 Squadron Flew its last sortie in the Whirlwind on 21st June 1943, an airfield attack at Poix. One aircraft was damaged and crash-landed near Manston. The pilot walked away unhurt. No. 263 Squadron, the first and last squadron to operate the Whirlwind, flew its last Whirlwind mission on 29 November 1943, turning in their aeroplanes and converting to the Hawker Typhoon in December that year.
Bearing in mind the relatively small number of Whirlwinds that reached the RAF, the type remained in combat service, virtually unmodified, for a remarkably long time… The Whirlwind, once mastered, certainly shouldered extensive responsibilities and the two squadrons were called upon to attack enemy targets from one end of the Channel to the other, by day and night, moving from airfield to airfield within southern England.
The twin-engine heavy fighter concept and aircraft design accelerated during the late 1930’s a keen proponent being Herman Goering. Largely it was somewhat of a blind alley of aircraft design during World War II. The Messerschmitt BF 110s sent over England during the Battle of Britain ended up requiring fighter escorts of BF 109s, which rather defeated the whole idea. The only truly successful examples being the Lockheed P-38 Lightening and the de Havilland Mosquito. Many would serve as excellent night fighters, a role that even converted bombers found their niche, such as the Junkers JU 88 and Dornier 217. The heavy fighter came into its own over Vietnam such as the McDonnell Douglas F-4 Phantoms or the Grumman F-14 Tomcat a few years later. Advances in Beyond Visual range (BVR) missiles negated the advantages of manoeuvrability and Mig 21s were effectively swept from the skies over North Vietnam and Libya.
But it is impossible not to speculate just how effective the Westland Whirlwind could have been, given a different set of priorities and circumstances.