View source for Westland Whirlwind (fighter)

{{Short description|1938 fighter aircraft family by Westland}}
{{About|the Second World War fighter aircraft|the postwar helicopter of the same name|Westland Whirlwind (helicopter)}}
{{Use dmy dates|date=November 2019}}
{{Use British English|date=March 2018}}
{{Infobox aircraft
  |name = Whirlwind
  |image =Westland_whirlwind.jpg
  |image_caption =Westland Whirlwind in a rare [[Second World War]] colour photograph
  |aircraft_type = [[Fighter aircraft]]
  |national_origin= United Kingdom
  |manufacturer =[[Westland Aircraft]]
  |designer =
  |first_flight =11 October 1938
  |introduction = June 1940
  |retired = December 1943
  |status =
  |primary_user = [[Royal Air Force]]
  |more_users =
  |produced = 1940 – January 1942
  |number_built = 114
  |variants =
}}

The '''Westland Whirlwind''' was a British twin-engined [[Fighter aircraft|fighter]] developed by [[Westland Aircraft]]. A contemporary of the [[Supermarine Spitfire]] and [[Hawker Hurricane]], it was the first single-seat, twin-engined, cannon-armed fighter of the [[Royal Air Force]].

When it first flew in 1938, the Whirlwind was one of the fastest combat aircraft in the world and, with four 20&nbsp;mm [[Hispano-Suiza HS.404]] [[autocannon]] in its nose, the most heavily armed.<ref>{{cite web|url=http://www.historyofwar.org/articles/weapons_westland_whirlwind.html|title = Westland Whirlwind |website=historyofwar.org  |last=Rickard |first= J |date=21 November 2007 }}</ref><ref name="Moyes 1967, pp. 278–279">Moyes 1967, pp. 278–279.</ref> Protracted development problems with its [[Rolls-Royce Peregrine]] engines delayed the project and only 114 Whirlwinds were built. During the Second World War, only three RAF squadrons were equipped with the aircraft and, despite its success as a fighter and [[ground attack]] aircraft, it was withdrawn from service in 1943.

==Design and development==
[[File:Westland Whirlwind prototype.jpg|thumb|Westland Whirlwind second prototype, ''L6845'', photographed at [[RAF Martlesham Heath|Martlesham Heath]] while being tested by the [[Aeroplane and Armament Experimental Establishment|A&AEE]], July 1939. Note the overall aluminium paint scheme, with polished spinners.<ref>Franks 2014, pp. 44–45, 56.</ref>]]

By the mid-1930s, aircraft designers around the world perceived that increased attack speeds were imposing shorter firing times on fighter pilots. This implied less ammunition hitting the target and ensuring destruction. Instead of two rifle-calibre machine guns, six or eight were required; studies had shown that eight machine guns could deliver 256 rounds per second.<ref>Buttler 2004, p.7</ref> The eight machine guns installed in the Hurricane fired rifle-calibre rounds, which did not deliver enough damage to quickly knock out an opponent, and were dispersed at ranges other than that at which they were [[Gun harmonisation|harmonised]]. Cannon, such as the French 20&nbsp;mm [[Hispano-Suiza HS.404]], which could fire explosive ammunition, offered more firepower and attention turned to aircraft designs which could carry four cannon. While the most agile fighter aircraft were generally small and light, their meagre fuel capacity limited their range and tended to restrict them to defensive and interception roles. The larger airframes and bigger fuel loads of twin-engined designs were favoured for long-range, offensive roles.

The first British specification for a high-performance machine-gun monoplane was [[List of Air Ministry Specifications|Air Ministry specification]] F.5/34 for a radial-engined fighter for use in the tropics which led to four aircraft designs{{Efn|these were the [[Gloster F.5/34]], [[Martin-Baker MB 2]], [[Bristol Type 146]], and [[Vickers Venom]]}}  but the aircraft produced were overtaken by the development of the new Hawker and Supermarine fighters.<ref>Buttler 2004, p.8</ref> The RAF [[Staff (military)|Air Staff]] thought that an experimental aircraft armed with the 20&nbsp;mm cannon was needed urgently and specification F.37/35 was issued to British aircraft companies in 1935. The specification called for a single-seat day and night fighter armed with four cannon. The top speed had to be at least {{convert|40|mph|abbr=on}} greater than that of contemporary bombers – at least {{convert|330|mph|abbr=on}} at {{convert|15000|ft|m|abbr=on}}.<ref>Bingham 1987, pp. 14–15.</ref><ref>Meekoms & Morgan 1994, pp. 217–218.</ref>

Eight aircraft designs from five companies were submitted in response to the specification. [[Boulton Paul Aircraft|Boulton Paul]] offered the P.88A and P.88B (two related single engine designs differing in engine: [[Bristol Hercules]] radial or [[Rolls-Royce Vulture]] in-line respectively), Bristol the single-engined Type 153 with cannon in wings and the twin-engined Type 153A with cannon in nose. Hawker offered a variant of the Hurricane, the [[Supermarine]] Type 312 was a variant of the company's [[Supermarine Spitfire|Spitfire]]{{efn|The Spitfire was then in development for F.37/34 and Supermarine suggested that a second set of wings would mean one aircraft design could meet both specifications}} and the Supermarine Type 313 a twin-engined ([[Rolls-Royce Goshawk]] or [[Hispano 12Y]]) design with four guns in the nose and potentially a further two firing through the propeller hubs if the 12T was used, the Westland P.9 had two [[Rolls-Royce Kestrel]] K.26 engines and a twin tail.<ref>Bingham 1987, pp. 14–16.</ref><ref>Buttler 2004, pp. 34–35</ref>

When the designs were considered in May 1936, there was concern that on the one hand a two engine design would be less manoeuvrable than a single-engined design and on the other that uneven recoil from cannon set in the wings would give less accurate fire. The conference favoured two engines with the cannon set in the nose and recommended the Supermarine 313.<ref name="secp36-7">Buttler 2004, pp. 36–37</ref> Although Supermarine's efforts were favoured due to their success with fast aircraft and the promise of the Spitfire which was undergoing trials, neither they nor Hawker were in a position to deliver a modified version of their single-engined designs quickly enough - over two years for Supermarine.<ref name="secp36-7"/> Westland, which had less work and was further advanced in their project, was chosen along with the P.88 and the Type 313 for construction. A contract for two P.9s was placed in February 1937 which were expected to be flying in mid-1938. The P.88s were ordered in December along with a Supermarine design to F37/35 but both were cancelled in January.<ref name="secp36-7"/>

The Westland design team, under the new leadership of [[W. E. W. Petter|W. E. W. "Teddy" Petter]]{{efn|Petter left Westland in 1944 and  later designed the [[English Electric Canberra]], [[English Electric Lightning]] and [[Folland Gnat]] }} designed an aircraft that employed state-of-the-art technology. The monocoque [[fuselage]] was tubular, with a [[T-tail]] at the end, although as originally conceived, the design featured a twin tail, which was discarded when large [[Flap (aeronautics)#Fowler flap|Fowler flaps]] were added that caused large areas of turbulence over the tail unit.<ref name="Green p. 51"/> By the employment of the T-tail, the elevator was moved up out of the way of the disturbed airflow caused when the flaps were down.<ref name="Green p. 51">Green 1964, p. 51.</ref> [[Leading-edge slats|Handley Page slats]] were fitted to the outer wings and to the leading edge of the radiator openings; these were interconnected by [[duraluminium]] torque tubes.<ref>Bingham 1987, p. 55.</ref> In June 1941, the slats were wired shut on the recommendation of the Chief Investigator of the Accident Investigation Branch, after two Whirlwinds crashed when the outer slats failed during vigorous manoeuvres; tests by the [[Aeroplane and Armament Experimental Establishment]] (A&AEE) confirmed that the Whirlwind's take-off and landing was largely unaffected with the slats locked shut, while the flight characteristics improved under the conditions in which the slats normally deployed.<ref>Corduroy 2013, p. 68.</ref>

The engines were developments of the Rolls-Royce Kestrel K.26, later renamed [[Rolls-Royce Peregrine|Peregrine]]. The first prototype, ''L6844'', used long exhaust ducts that were channelled through the wings and fuel tanks, exiting at the wing's trailing edge. This configuration was quickly changed to more conventional, external exhausts after Westland's chief test pilot [[Harald Penrose]] nearly lost control when an exhaust duct broke and heat-fractured an aileron control rod.<ref>Bingham 1987, p. 28.</ref> The engines were cooled by ducted radiators, which were set into the leading edges of the wing centre-sections to reduce drag.<ref name="Buttler37" /> The airframe was built mainly of stressed-skin [[duralumin]], with the exception of the rear-fuselage, which used a [[magnesium]] alloy stressed skin.<ref>Bingham 1987, p. 57.</ref><ref name="Buttler37">Buttler 2004, p. 37.</ref> With the pilot sitting high under one of the world's first full [[bubble canopy|bubble canopies]] and the low and forward location of the wing, all round visibility was good (except for directly over the nose). Four 20&nbsp;mm cannon were mounted in the nose; the 600&nbsp;round/minute fire rate made it the most heavily armed fighter aircraft of its era.<ref>Moyes 1967, p.3.</ref> The clustering of the weapons also meant that there were no convergence problems as with wing-mounted guns. Hopes were so high for the design that it remained top secret for much of its development, although it had already been mentioned in the French press.

''L6844'' first flew on 11 October 1938, construction having been delayed chiefly due to the new features and also because of the late delivery of the engines and undercarriage.<ref name="Buttler37" /> ''L6844'' was passed to RAE Farnborough at the end of the year, while further service trials were later carried out at [[RAF Martlesham Heath|Martlesham Heath]].<ref>Moyes 1967, p. 5.</ref> The Whirlwind exhibited excellent handling characteristics and proved to be very easy to fly at all speeds. The only exception was the inadequate directional control during take-off which necessitated an increased rudder area above the tailplane.<ref name="Green p. 51"/>

[[File:Whirlwind Mk I in flight, loaded w 2 500-lb GP bombs underwing, AAEE Boscombe Down.jpg|thumb|Whirlwind I undergoing fighter-bomber trials at the A&AEE.]]
The Whirlwind was quite small, only slightly larger than the Hurricane but with a smaller frontal area. The landing gear was fully retractable and the entire aircraft had a very clean finish with few openings or protuberances. Radiators were in the leading edge on the inner wings rather than below the engines, which contributed to the overheating problems.<ref>{{cite web|url=https://www.dingeraviation.net/westland/whirlwind.html |title=The Westland Whirlwind British fighter aircraft of WW2 |publisher=Dingeraviation.net |date= |accessdate=2022-05-02}}</ref> This careful attention to streamlining and two {{cvt|885|hp}} Peregrine engines powered it to over {{cvt|360|mph}}, the same speed as the latest single-engine fighters.<ref name="Green p. 51"/> The aircraft had short range, under {{convert|300|mi|km|abbr=on}} combat radius, which made it as marginal as an escort as the Hurricane and Spitfire. The first deliveries of Peregrine engines did not reach Westland until January 1940.

By late 1940, the Spitfire was scheduled to mount {{cvt|20|mm}} cannon so the "cannon-armed" requirement was being met and by this time, the role of escort fighters was becoming less important as [[RAF Bomber Command]] turned to night flying. The main qualities the RAF were looking for in a twin-engine fighter were range and carrying capacity (to allow the large radar apparatus of the time to be carried), in which requirements the [[Bristol Beaufighter]] could perform just as well as or even better than the Whirlwind.

Production orders were contingent on the success of the test programme; although ACAS was impressed by the design the highly experimental design needed careful examination.<ref name="Buttler37" /> Delays caused by over 250 modifications to the two prototypes led to an initial production order for 200 aircraft being held up until January 1939, followed by a second order for a similar number, deliveries to fighter squadrons being scheduled to begin in September 1940.<ref>James 1991, p. 263.</ref> Earlier, due to the lower expected production at Westland, there had been suggestions that production should be by other firms ([[Fairey Aviation Company|Fairey]] or Hawker) and an early 1939 plan to build 800 of them at the [[Castle Bromwich Assembly#Castle Bromwich Aircraft Factory|Castle Bromwich shadow factory]] was dropped in favour of Spitfire production; instead a further 200 would be built by Westland.<ref name="Buttler37" /><ref>Corduroy 2013, p. 33.</ref>

Despite the Whirlwind's promise, production ended in January 1942, after the completion of just 112 production aircraft (plus the two prototypes). Rolls-Royce needed to concentrate on the development and production of the [[Rolls-Royce Merlin|Merlin]] engine, and the troubled [[Rolls-Royce Vulture|Vulture]] engines, rather than the Peregrine.<ref>Corduroy 2013, pp. 35–36.</ref> Westland was aware that its design – which had been built around the Peregrine – was incapable of using anything larger without an extensive redesign.<ref>Buttler 2004, p. 38.</ref> After the cancellation of the Whirlwind, Petter campaigned for the development of a Whirlwind '''Mk II''', which was to have been powered by an improved {{cvt|1,010|hp}} Peregrine, with a better, higher-altitude supercharger, also using 100 octane fuel, with an increased boost rating.{{efn|Using 100 octane fuel, the standard Peregrine could use up to {{cvt|+9|lb/sqin|kPa}} boost for take-off or operations.<ref>Air Ministry 1940, Vol 1, Sect 2 Para 29.</ref> The improved Peregrine envisaged by Petter would use {{cvt|+12|lb/sqin|kPa}} and be rated to {{cvt|20000|ft}}.<ref name="Cor44">Corduroy 2013, p. 44.</ref> }} This proposal was aborted when Rolls-Royce cancelled work on the Peregrine.<ref>Corduroy 2013, pp. 40–42</ref>{{efn|Additional proposals included the use of Bristol-built or American radial engines, while another possibility mooted in 1941 was to use two {{cvt|1400|hp}} Merlin XX engines.<ref>Bingham 1987, pp. 40, 42.</ref><ref name="Cor44"/> }} Building a Whirlwind consumed three times as much alloy as a Spitfire.<ref name="Cor44"/>

==Operational history==

[[File:Whirlwind 263 Squadron Winter 1941-1942.jpg|thumb|Whirlwind Mark I, P7116 ''HE-F'' ''Bellows Argentina No. 2'', flown by the Officer Commanding 263 Squadron RAF based at Colerne, Wiltshire, on the snow-covered airfield at Charmy Down, Somerset.]]
Many pilots who flew the Whirlwind praised its performance. Sergeant G. L. Buckwell of 263 Squadron, who was shot down in a Whirlwind over [[Cherbourg]], later commented that the Whirlwind was "great to fly – we were a privileged few... 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".<ref>Mason 1969</ref> Another 263 Squadron pilot said "It was regarded with absolute confidence and affection".<ref name="Robertson p. 16."/> In contrast, the test pilot [[Eric Brown (pilot)|Eric Brown]] described the aircraft as "under-powered" and "a great disappointment".<ref>{{citation |archive-url=https://web.archive.org/web/20130330111728/http://www.youtube.com/watch?v=PkicKdqxPSc&gl=US&hl=en |archive-date=2013-03-30 |publisher=Royal Aeronautical Society |date=27 Sep 2010 |title=Captain Eric 'Winkle' Brown - test pilot legend (Part2)  |url=https://www.youtube.com/watch?v=PkicKdqxPSc|via=Youtube |url-status=live}}</ref>

An aspect of the type often criticised was the high landing speed imposed by the wing design.{{citation needed|date=February 2016}} Because of the low production level, based on the number of Peregrines available, no redesign of the wing was contemplated, although Westland did test the effectiveness of leading-edge slats to reduce speeds. When the slats were activated with such force that they were ripped off the wings, the slats were wired shut.<ref>James 2006, p. 65.</ref>

As the performance of the Peregrine engines fell off at altitude, perhaps a function of the propeller profile and the constant speed prop controller,<ref>{{cite web |last1=Bearman |first1=Matt |title=It Wasn't the Engine That Did in the Westland Whirlwind — What Was It? |url=https://www.historynet.com/it-wasnt-the-engine-that-did-in-the-westland-whirlwind-what-was-it/ |website=HistoryNet |date=2 August 2023 |access-date=24 August 2023}}</ref> the Whirlwind was most often used in ground-attack missions over France, attacking German airfields, [[marshalling yard]]s, and railway traffic. The Whirlwind was used to particularly good effect as a gun platform for destroying locomotives. Some pilots were credited with several trains damaged or destroyed in a mission. The aircraft was also successful in hunting and destroying German [[E-boats]] which operated in the [[English Channel]]. At lower altitudes, it could hold its own against the [[Messerschmitt Bf 109]]. Though the Peregrine was a much-maligned engine, it was more reliable than the troubled [[Napier Sabre]] engine used in the [[Hawker Typhoon]], the Whirlwind's successor.{{citation needed|date=December 2010}} The twin engines meant that seriously damaged aircraft were able to return with one engine knocked out.<ref>Bingham 1987, p. 45</ref> The placement of the wings and engines ahead of the cockpit allowed the aircraft to absorb a great deal of damage, while the cockpit area remained largely intact. The rugged frame of the Whirlwind gave pilots greater protection than contemporary aircraft during crash landings and ground accidents.{{citation needed|date=December 2010}} According to P. J. R. Moyes

{{Blockquote|The basic feature of the Whirlwind was its concentration of firepower: its four {{sic|hide=y|closely|-}}grouped heavy cannon in the nose had a rate of fire of 600 lb./minute – which, until the introduction of the Beaufighter, placed it ahead of any fighter in the world. Hand in hand with this dense firepower went a first-rate speed and climb performance, excellent manoeuvrability, and a fighting view hitherto unsurpassed. The Whirlwind was, in its day, faster than the Spitfire down low and, with lighter lateral control, was considered to be one of the nicest "twins" ever built… From the flying viewpoint, the Whirlwind was considered magnificent.<ref name="Moyes 1967, pp. 278–279"/>}}

The first Whirlwinds went to [[No. 25 Squadron RAF|25 Squadron]] based at North Weald. The squadron was fully equipped with [[radar]]-equipped [[Bristol Blenheim|Bristol Blenheim IF]] night fighters when [[Squadron Leader]] K. A. K. MacEwen flew prototype Whirlwind ''L6845'' from [[RAF Boscombe Down]] to [[RAF North Weald]] on 30 May 1940.<ref name="James west p268">James 1991, p. 268.</ref> The following day it was flown and inspected by four of the squadron's pilots and the next day was inspected by the [[Secretary of State for Air]], Sir [[Archibald Sinclair]] and [[Hugh Trenchard, 1st Viscount Trenchard|Lord Trenchard]].{{citation needed|date=May 2012}} The first two production Whirlwinds were delivered in June to 25 Squadron for night-flying trials.<ref name="James west p268-9">James 1991, pp. 268–269.</ref><ref name="ae99 p11">Buttler 2002, p. 11.</ref> It was then decided to re-equip 25 Squadron with the two-seat Bristol Beaufighter night fighter, as it was already an operational night fighter squadron.<ref name="James west p269">James 1991, p. 269.</ref>

The first Whirlwind squadron would be [[No. 263 Squadron RAF|263 Squadron]], which was reforming at [[RAF Grangemouth]], after disastrous losses in the Norwegian Campaign. The first production Whirlwind was delivered to 263 Squadron by its commander, Squadron Leader H. Eeles on 6 July.<ref name="Aerofeb85 p62">Heffernan 1985, p. 62.</ref> Deliveries were slow, with only five on strength with 263 Squadron on 17 August 1940 and none serviceable.<ref name="aiMar95 p162">Price 1995, p. 162.</ref> (The squadron supplemented its strength with Hawker Hurricanes to allow the squadron's pilots to fly in the meantime.)<ref name="James west p269"/> Despite the [[Battle of Britain]] and the consequent urgent need for fighters, 263 Squadron remained in Scotland, [[Air Chief Marshal]] [[Hugh Dowding]], in charge of [[RAF Fighter Command]], stated on 17 October that 263 could not be deployed to the south because "there was no room for 'passengers' in that part of the world".<ref name="ae99 p11"/>

[[File:Westland Whirlwind 263 Sqn Exeter, banking awf cam, fighter paint 1940nov27-crop.jpg|thumb|Whirlwind showing the new "Type B" paint scheme introduced in November 1940: while the black underside to the port wing was temporary, the sky fuselage band was a longer-lasting change.]]
The first Whirlwind was written off on 7 August when [[Pilot Officer]] McDermott had a tyre blow out while taking off in ''P6966''. In spite of this he managed to get the aircraft airborne. Flying Control advised him of the dangerous condition of his undercarriage. PO McDermott bailed out of the aircraft between Grangemouth and Stirling. The aircraft dived in and buried itself eight feet into the ground.<ref name="RAF Westland Whirlwind / P6966.">{{citation |url=http://www.aircrashsites-scotland.co.uk/whirlwind_lanton.htm |archive-url=https://web.archive.org/web/20181026000045/http://www.aircrashsites-scotland.co.uk/whirlwind_lanton.htm |archive-date=2018-10-26 |title= RAF Westland Whirlwind / P6966. |website=Air Crash Sites Scotland |date=2011 |access-date=20 September 2013}}</ref> On recent inspection of the salvaged wreck of P6966, it was noticed that the defective tyre fitted was not of the correct size for a Whirlwind. Instead, it was the correct size for a Hurricane which 263 Squadron was also flying.

No. 263 Squadron moved south to [[Exeter International Airport|RAF Exeter]] and was declared operational with the Whirlwind on 7 December 1940.<ref name="Aerofeb85 p62"/> Initial operations consisted of convoy patrols and anti [[E-boat]] missions.<ref name="Aerofeb85 p62"/><ref name="High p70-1">James 2006, pp. 70–71.</ref> The Whirlwind's first confirmed kill occurred on 8 February 1941, when an [[Arado Ar 196]] floatplane was shot down; the Whirlwind responsible also crashed into the sea and the pilot was killed.<ref name="High p71">James 2006, p. 71.</ref> From then on the squadron was to have considerable success with the Whirlwind while flying against enemy [[Junkers Ju 88]], [[Dornier Do 217]], Messerschmitt Bf 109s and [[Focke-Wulf Fw 190]]s.

263 Squadron also occasionally carried out day bomber escort missions with the Whirlwinds. One example was when 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.<ref name="aimar95 p163">Price 1995, p. 163.</ref><ref name="hardest p118-9">Richards 1995, pp. 118–119.</ref>

The squadron mostly flew low-level attack sorties across the channel ("[[Glossary of RAF code names#rhubarb|Rhubarbs]]" against ground targets and "[[Glossary of RAF code names#roadstead|Roadstead]]" attacks against shipping).<ref name="High p71"/> The Whirlwind proved a match for German fighters at low level, as demonstrated on 6 August 1941, when four Whirlwinds on an anti-shipping strike were intercepted by a large formation of Messerschmitt Bf 109s and claimed three Bf 109s destroyed for no losses.<ref name="aimar95 p163"/> A second Whirlwind squadron, [[No. 137 Squadron RAF|137]], formed in September 1941, specialising in attacks against railway targets.<ref name="High p71"/><ref name="ae99 p15">Buttler 2002, p. 15.</ref> In the summer of 1942, both squadrons were fitted with racks to carry two {{convert|250|or|500|lb|kg|abbr=on}} bombs, and nicknamed 'Whirlibombers'.<ref>Buttler 2002, pp. 14–15.</ref><ref name="James west p270">James 1991, p. 270.</ref> These undertook low-level cross-channel "Rhubarb" sweeps, attacking locomotives, bridges, shipping and other targets.

[[File:3 Westland Whirlwinds of 263 Sqn Exeter(Devon), flying in stepped line-astern formation over West Country.jpg|thumb|Three Westland Whirlwinds of 263 Squadron in stepped line-astern formation]]
The last Whirlwind mission to be flown by 137 Squadron was on 21 June 1943, when five Whirlwinds took off on a "Rhubarb" attack against the German airfield at Poix.<ref name="ae99 p15"/> P6993 was unable to locate the target and instead bombed a supply train north of [[Rue, Somme|Rue]]. While returning, the starboard throttle jammed in the fully open position and the engine eventually lost power. It made a forced landing in a field next to [[RAF Manston]] but the aircraft was a write-off, although, as in many other crash landings in the type, 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.<ref name="High p71-2">James 2006, pp. 71–72.</ref> On 1 January 1944, the type was declared obsolete.<ref name="High p73">James 2006, p. 73.</ref> The remaining serviceable aircraft were transferred to No. 18 Maintenance Unit, while those undergoing repairs or overhaul were allowed to be repaired only if they were in near-flyable condition. An official letter forbade aircraft needing repair to be worked on.

[[File:Whirlwind Mk I, 263 Sqn Exeter, in flight over West Country.jpg|thumb|''P6969 'HE-V''' of 263 in flight over the West Country]]
The aircraft was summed up by Francis Mason as follows:

{{Blockquote|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.<ref>Mason 1969, p. 64.</ref>}}

==Variants==
'''P.9 prototype'''
:Single-seat twin-engine fighter aircraft prototype. Two built (L6844 and L6845), can be distinguished from later production samples by the mudguards above the wheels (as did the first production sample, P6966), the exhaust system and the so-called 'acorn' on the joint between fin and rudder. L6844 had a distinctive downward kink to the front of its pitot tube, atop the tail not seen again in following models. L6844's colour was dark grey. L6844 had opposite-rotation engines, L6845 had engines that rotated in the same direction; this carried over to production machines.

'''Whirlwind I'''
:Single-seat twin-engine fighter aircraft, 400 ordered, 116 built (2 prototypes and 114 production versions).

'''Whirlwind II'''
:Single-seat twin-engine fighter-bomber aircraft, fitted with underwing bomb racks, were nicknamed "Whirlibombers". At least 67 conversions made from the original Mk I fighter.

'''Experimental variants'''
A Mk I Whirlwind was tested as a night fighter in 1940 with No. 25 Squadron.
The first prototype was armed with an experimental twelve 0.303 (7.7&nbsp;mm) machine guns and another one 37&nbsp;mm cannon.<ref name="Robertson p. 16.">Robertson 1970, p. 16.</ref><ref>Green 1961, p. 125.</ref>
<!-- Exhaust "muffs" were fitted to conceal flames, as well as landing lights suitable for night flying.<ref>[http://www.flightglobal.com/pdfarchive/view/1942/1942%20-%200500.html p196] ''Flight'' 5 March 1942.</ref>   -->

'''Merlin variant'''
Westland proposed fitting Merlin engines in a letter to Air Marshal [[Sholto Douglas, 1st Baron Douglas of Kirtleside|Sholto Douglas]].<ref>[http://discovery.nationalarchives.gov.uk/details/r/C506723 PRO/NA air 16-326 page 82A]</ref> The proposal was rejected but Westland used the design work already performed in developing the [[Westland Welkin|Welkin]] high-altitude fighter.

==Operators==
'''{{UK}}'''
* [[Royal Air Force]]
** [[No. 25 Squadron RAF]] tested three aircraft between May and July 1940. (might have carried code letters "ZK")
** [[No. 263 Squadron RAF]] operated Whirlwinds between July 1940 and December 1943. Aircraft had applied the squadron's "HE" code letters.
** [[No. 137 Squadron RAF]] operated Whirlwinds between September 1941 and June 1943. Aircraft had applied the squadron's "SF" code letters.
'''US Navy'''
One aircraft P6994 was sent to the US for trials in June 1942 and survived there until at least late 1944.

==Survivors==
After retirement in December 1943, all but one of the surviving Whirlwinds were sent to [[No. 18 Maintenance Unit RAF]] at [[RAF Dumfries]], Scotland, where they were scrapped. ''P7048'' was retained by Westland and was granted a civil [[certificate of airworthiness]] on 10 October 1946, with the [[Aircraft registration|registration]] ''G-AGOI''. It was used as a company hack for a short time before being withdrawn in 1947 and scrapped.<ref name="High p73"/><ref name="ae99 p16">Buttler 2002, p. 16.</ref> In October 1979, the remains of Whirlwind P6966, the first Whirlwind to be lost, were recovered near Grangemouth by enthusiasts in a dig group. The two Peregrine engines were recovered, as well as many pieces of the airframe.<ref name="RAF Westland Whirlwind / P6966."/> The Whirlwind Fighter Project began building a full-scale replica Whirlwind in 2011–2012. By 2023 an authentic cockpit section had been built and put on display at the [[Kent Battle of Britain Museum]] in [[Hawkinge]].<ref>{{Cite web |title=whirlwind |url=https://www.whirlwindfp.org/ |access-date=2023-07-23 |website=WFP |language=en}}</ref> Plans for a 2/3 scale replica were marketed for home building in the late 1970s and early 1980s as the [[Butterworth Westland Whirlwind]].{{sfn|Taylor|1982|p=534}}

==Specifications (Whirlwind I)==
[[File:Whirlwindfighterproject FA 18181s.jpg|thumb|Chief test pilot of Westland, [[Harald Penrose]] flying one of the last production Whirlwinds ''P7110''.]]
{{Aircraft specs
|ref=Westland's Double Trouble<ref name="Aeromay06 p69">James 2006, p. 69.</ref>
|prime units?=imp
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|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil='''root:''' [[NACA airfoil|NACA 23017]]; '''tip:''' [[NACA airfoil|NACA 23008]]
|empty weight lb=8310
|empty weight note=
|gross weight lb=10356
|gross weight note=
|max takeoff weight lb=11445
|max takeoff weight note=
|fuel capacity=
|more general=
<!--
        Powerplant
-->
|eng1 number=2
|eng1 name=[[Rolls-Royce Peregrine I]]
|eng1 type=V-12 liquid-cooled piston engines
|eng1 hp=885
|eng1 note=at {{cvt|10000|ft}} with [[100 octane]] fuel

|prop blade number=3
|prop name=[[de Havilland]]-Hydromatic
|prop dia ft=10
|prop dia note= variable-pitch propellers
<!--
        Performance
-->
|max speed mph=360
|max speed note=at {{cvt|15000|ft}}
|max speed mach=<!-- supersonic aircraft -->
|cruise speed mph=
|cruise speed note=
|stall speed mph=95
|stall speed note=flaps down
|never exceed speed mph=
|never exceed speed note=
|minimum control speed mph=
|minimum control speed note=
|range miles=800
|range note=<ref name="James west p370-1">James 1991, pp. 370–371.</ref>
|combat range miles=150
|combat range note=as low altitude fighter, with normal reserves<ref name="aimar95 p163"/>
|ferry range miles=
|ferry range note=
|endurance=<!-- if range unknown -->
|ceiling ft=30300
|ceiling note=
|g limits=<!-- aerobatic -->
|roll rate=<!-- aerobatic -->
|climb rate ftmin=
|climb rate note=
|time to altitude={{cvt|15000|ft}} in 5 minutes 54 seconds, {{cvt|30000|ft}} in 20 minutes 30 seconds
|wing loading lb/sqft=45.6
|wing loading note=
|fuel consumption lb/mi=
|power/mass=
|more performance=
<!--
        Armament
-->
|guns=4 × [[Hispano 20 mm cannon]] with 60 rounds per gun
|bombs=optionally 2 × 250 lb (115 kg) or 500 lb (230 kg) bombs
}}

==See also==
{{aircontent
|related=
* [[Westland Welkin]]
|similar aircraft=
* [[Focke-Wulf Fw 187]]
* [[Fokker D.XXIII]]
* [[Gloster F.9/37]]
* [[Grumman XF5F Skyrocket]]
* [[Grumman XP-50]]
* [[IMAM Ro.57]]
* [[Kawasaki Ki-45]]-II
* [[Lockheed P-38 Lightning]]
* [[Mikoyan-Gurevich DIS]]
* [[Tairov Ta-3]]

|lists=<!-- related lists -->
* [[List of aircraft of the Royal Air Force]]
* [[List of aircraft of World War II]]
|see also=<!-- other relevant information -->
}}

==References==

===Notes===
{{Reflist|group=nb}}
{{notelist}}

===Citations===
{{Reflist|20em}}

===Bibliography===
* Air Ministry. ''Pilot's Notes: The Whirlwind I Aeroplane, Two Peregrine I Engines. Air Publication 1709A''. London, UK: Air Ministry, June 1940.
*{{cite journal |last1=Bearman |first1=Matt |title=The Whirlwind Becalmed|journal=The Aviation Historian |date=2017 |issue=20 |pages=36–44 |issn=2051-1930}}
* Bingham, Victor. ''Whirlwind, The Westland Whirlwind Fighter''. Shrewsbury, UK: Airlife Publishing Ltd., 1987. {{ISBN|1-85310-004-8}}.
* Buttler, Tony. ''British Secret Projects: Fighters and Bombers 1935–1950''. Earl Shilton, Leicester, UK: Midland, 2004. {{ISBN|1-85780-179-2}}.
* Buttler, Tony. "Reap The Whirlwind: Britain's Pioneer Cannon Fighter". ''[[Air Enthusiast]]''. No. 99, May/June 2002, pp.&nbsp;2–16. {{ISSN|0143-5450}}.
* Cordury, Niall. ''Whirlwind; Westland's Enigmatic Fighter''. Stroud, UK: Fonthill Media Limited, 2013. {{ISBN|978-1-78155-037-3}}
* Franks, Richard A. ''The Westland Whirlwind: A Detailed Guide to the RAF's Twin-engine Fighter (Airframe Album 4)''. Bedford, UK: Valiant Wings Publishing, 2014. {{ISBN|978-0-9575866-3-5}}
* Green, William, ed. "Foremost with Four Cannon." ''Flying Review International'', Volume 19, No. 7, April 1964.
* Green, William. ''Warplanes of the Second World War, Fighters, Vol. 2''. London: Macdonald, 1961.
* Heffernan, Terry. "Something Special from Somerset – Part 2". ''[[Aeroplane Monthly]]''. Vol. 13, No. 2, February 1985, pp.&nbsp;60–64. {{ISSN|0143-7240}}.
* James, Derek N. ''Westland Aircraft since 1915''. Annapolis, Maryland: Naval Institute Press, 1991. {{ISBN|1-55750-921-2}}.
* James, Derek N. "Westland's Double Trouble" (Database). ''[[Aeroplane Monthly|Aeroplane]]'', Vol. 34, No. 5, May 2006, pp.&nbsp;60–73. {{ISSN|0143-7240}}.
* {{cite book |last = Lawrence |first = Joseph |title = The Observer's Book Of Airplanes |location = London and New York |publisher = Frederick Warne & Co |year = 1945}}
* Mason, Francis K. ''Royal Air Force Fighters of World War Two, Volume One''. Windsor, Berkshire, UK: Hylton Lacy Publishers Ltd., 1969.
* Meekoms, K. J. and E. B Morgan. ''The British Aircraft Specifications File: British Military and Commercial Aircraft Specifications 1920–1949''. Tonbridge, Kent, UK: Air-Britain (Historians) Ltd., 1994. {{ISBN|0-85130-220-3}}
* Moyes, Philip J.R. ''Westland Whirlwind (Profile No. 191)''. London: Profile Publications, 1967.
* Price, Alfred. "The Vortex from Yeovil: The Story of the Westland Whirlwind Fighter". ''[[Air International]]''. Vol. 48 No. 3, March 1995, pp.&nbsp;157–164. {{ISSN|0306-5634}}.
* Richards, Denis. ''The Hardest Victory: RAF Bomber Command in the Second World War''. London: Coronet, 1995. {{ISBN|0-340-61720-9}}.
* {{cite journal |last1=Roba |first1=Jean-Louis |last2=Cony |first2=Christophe |name-list-style=amp |title=Donnerkeil: 12 février 1942 |journal=Avions: Toute l'Aéronautique et son histoire |date=September 2001 |issue=102 |pages=46–53 |trans-title=Operation Donnerkeil: 12 February 1942 |language=fr |issn=1243-8650}}
* Robertson, Bruce. ''Westland Whirlwind Described''. Dandenong, Victoria, Australia: Kookaburra Technical Publications, 1970. {{ISBN|0-85880-004-7}}
* {{cite book |last=Taylor |first=J. W. R. |author-link=John W. R. Taylor |title=Jane's All The World's Aircraft 1982–83 |year=1982 |location=London |publisher=Jane's Yearbooks |isbn=0-7106-0748-2}}

==Further reading==
* Crawford, Alex and Phil H. Listemann. "Westland Whirlwind Mk.I." (Allied Wings No.4). London: Casemate Pub & Book Dist. Llc, 2008. {{ISBN|2-9526381-8-7}}
* Green, William and Gordon Swanborough. ''WW2 Aircraft Fact Files – RAF Fighters, Part 3''. London: Jane's, 1981. {{ISBN|0-7106-0119-0}}
* Hall, Alan W. ''Westland Whirlwind F.Mk.I'' (Warpaint Series no.54). Luton, Berfordshire, UK: Warpaint Books, 2006. No ISBN.
* James, Derek N. ''Westland'' (Images of England). Gloucestershire, UK: Tempus Publishing Ltd., 1997. {{ISBN|0-7524-0799-6}}
* James, Derek N. ''Westland: A History''. Gloucestershire, UK: Tempus Publishing Ltd., 2002. {{ISBN|0-7524-2772-5}}
* Mondey, David. '' Westland '' (Planemakers 2). London: Jane's Publishing Company, 1982. {{ISBN|0-7106-0134-4}}
* Morgan, Eric B. "Westland P.9 Whirlwind." ''Twentyfirst Profile'', Vol. 2, No. 14. New Milton, Hertfordshire, UK: 21st Profile Ltd. {{issn|0961-8120}}
* Ovcácík, Michal and Karel Susa. '' Westland Whirlwind: Mk.I Fighter, Mk.I fighter-bomber''. Prague, Czech Republic: Mark 1 Ltd., 2002. {{ISBN|80-902559-6-5}}
*{{cite journal |last1=Stoddart |first1=Paul |title=Storming Performance: The Westland Whirlwind Revisisted / Part One |journal=The Aviation Historian |date=2023 |issue=42 |pages=86–93 |issn=2051-1930}}
*{{cite journal |last1=Stoddart |first1=Paul |title=Storming Performance: The Westland Whirlwind Revisisted / Part Two |journal=The Aviation Historian |date=2023 |issue=43 |pages=76–84 |issn=2051-1930}}
* Taylor, John W.R. "Westland Whirlwind" ''Combat Aircraft of the World from 1909 to the Present''. New York: G.P. Putnam's Sons, 1969. {{ISBN|0-425-03633-2}}

==External links==
{{Commons category}}
* [http://www.flightglobal.com/pdfarchive/view/1942/1942%20-%200498.html The Westland Whirlwind] ''Flight'' 5 March 1942
* [https://books.google.com/books?id=RicDAAAAMBAJ&dq=popular+science+1930&pg=PA65 "Flying Arsenal Pace Bombers on Raids."] ''Popular Science'', June 1942, p.&nbsp;65.
* [http://www.cbrnp.com/profiles/quarter2/whirlwinds.htm colour profiles]
* [http://www.flightglobal.com/pdfarchive/view/1942/1942%20-%201295.html Aircraft Types and their Characteristics – Whirlwind] ''Flight'' 18 June 1942
* [https://www.whirlwindfighterproject.co.uk/ Whirlwind Fighter Project]

{{Westland aircraft}}
{{Authority control}}

{{DEFAULTSORT:Westland Whirlwind (Fighter)}}
[[Category:1930s British fighter aircraft]]
[[Category:Westland aircraft|Whirlwind (Fighter)]]
[[Category:Low-wing aircraft]]
[[Category:Cruciform tail aircraft]]
[[Category:Twin piston-engined tractor aircraft]]
[[Category:Aircraft first flown in 1938]]
[[Category:Aircraft with retractable conventional landing gear]]