Editing Hawker Tempest (section)

=== Prototypes ===
[[File:Hawker Tempest II LA602 - Prototype.jpg|thumb|First prototype Tempest Mk. II ''LA602'', again with the small tail unit.]]
On 18 November 1941, a contract was issued by the Air Ministry for a pair of [[prototype]]s of the "Typhoon Mark II"; the new fighter was renamed "Tempest" on 28 February 1942.<ref name=Thomas105/><ref name=Mason67_4/>{{#tag:ref|The renaming of the "Typhoon II" to "Tempest" was considered to be an indication of the level of changes and increasing number of refinements that had made the two aircraft more unique and distinguished from one another.<ref name=Mason67_4/>|group=nb}}{{Efn|Buttler gives 6 August as the official renaming, and notes the suggestion came from Camm in January.<ref>Buttler 2004 p18</ref>}} Complications were added to the Tempest program by external factors in the form of engine issues: the [[Rolls-Royce Vulture]] engine and corresponding [[Hawker Tornado]] aircraft which was being developed in parallel to the Typhoon were both terminated.  This measure turned out to be prudent, as engine development was not trouble-free on some of the variants of the Tempest.<ref name=Mason67_4_6>Mason 1967, pp. 4-6.</ref> The [[Bristol Centaurus]] radial engine was now also considered for equipping the Typhoon and Camm was forewarned in October 1941 to expect a request for a Centaurus to be fitted. This was confirmed in February as an order for six prototypes with the Centaurus; the DTD stating that the development was highest priority.<ref>Buttler 2004 p18</ref>  

Delays with the Sabre IV development affected the project. With the expected first flight date for the Tempest was September 1942, the engine for ''HM595'' was changed to a Sabre II complete with the Typhoon cooling system and under nose radiator.<ref name=":0" /> Due to this previous experience on other programmes, the Air Ministry was sufficiently motivated to request that Tempest prototypes be built using different engines so that, if a delay hit one engine, an alternative powerplant would already be available.<ref name="Mason67_4" />An order was approved for six more prototypes with alternate engines in May and the contract for two with Sabres, two with Centaurus and two with [[Rolls-Royce Griffon|Rolls Royce Griffons]] followed in June.<ref name=":0" /> 

[[File:Hawker Tempest Mk III.jpg|thumb|Tempest Mk. III prototype ''LA610.'']]
The six prototypes built were as follows:<ref name=Mason91_331>Mason 1991, p. 331.</ref><ref name=Mason67_4_5>Mason 1967, pp. 4–5.</ref>
* One Tempest Mk.I ([[serial number]] ''HM599''), equipped with the Napier Sabre Mk.IV engine
* Two Tempest Mk.II (serial numbers ''LA602'' and ''LA607''), equipped with the Bristol Centaurus Mk.IV engine (LA607 later receiving a Centaurus Mk.V)<ref name="hawkertempest.se/markii"/>
* One Tempest Mk.III (serial number ''LA610''), equipped with the Rolls-Royce Griffon 85 engine (originally planned for the Griffon IIB)<ref>{{Cite web|date=2018-02-21|title=HAWKER'S FASTEST FURY – LA610|url=https://navalairhistory.com/2018/02/21/hawkers-fastest-fury-la610/|access-date=2021-08-14|website=navalairhistory.com}}</ref>
* One Tempest Mk.IV (serial number ''LA614''), which was never completed but planned to be equipped with a Griffon 61 engine
* One Tempest Mk.V (serial number ''HM595''), equipped with the Napier Sabre Mk.II engine

The Tempest Mk.I featured other new features, such as a clean single-piece sliding canopy in place of the car-door framed canopy, and it used wing radiators instead of the "chin" radiator.{{#tag:ref|The use of wing radiators was a point of controversy, with Air Ministry officials approaching Camm with doubts concerning its vulnerability to battle damage.<ref name=Mason67_5/>|group=nb}} Due to development difficulties with the Sabre IV engine and its wing radiators, the completion of the Mk.I prototype, ''HM599'', was delayed, and thus it was the Mk.V prototype, ''HM595'', that would fly first.<ref name=Mason67_5/>

{{Multiple image|total_width=230|perrow=1|header=Cockpit and rudder evolution|image1=Hawker Tempest ExCC.jpg|caption1=Tempest Mk.V prototype ''HM595'' with early "car door" cockpit structure and small tail unit.|image2=Hawker Tempest V parked 1944 (cropped).jpg|caption2=Tempest Mk.V production model with late "[[bubble canopy]]" cockpit structure and large tail unit.}}
On 2 September 1942, the Tempest Mk.V prototype, ''HM595'', conducted its [[maiden flight]], flown by Philip Lucas from [[Langley, Berkshire#Langley Airfield|Langley, Berkshire]], England.<ref name=Mason67_5/> ''HM595'', which was powered by a Sabre II engine, retained the Typhoon's framed [[Canopy (aircraft)|canopy]] and car-style door, and was fitted with the "chin" radiator, similar to that of the Typhoon.<ref name=Mason91_331/> It was quickly fitted with the same [[bubble canopy]] fitted to Typhoons, and a modified [[fin]] that almost doubled the vertical tail surface area, made necessary because the directional stability with the original Typhoon fin had been reduced over that of the Typhoon by the longer nose incurred by the new fuel tank. The horizontal tailplanes and [[Elevator (aircraft)|elevators]] were also increased in span and chord; these were also fitted to late production Typhoons.<ref name=Mason91_331/><ref name=Mason67_6/> [[Test pilot]]s found the Tempest a great improvement over the Typhoon in performance; in February 1943 the pilots from the [[Aeroplane and Armament Experimental Establishment|Aeroplane & Armament Experimental Establishment]] at [[MOD Boscombe Down|Boscombe Down]] reported that they were impressed by "a manoeuvrable and pleasant aircraft to fly with no major handling faults".<ref name=Thomas106/>

On 24 February 1943, the second prototype ''HM599'' first flew, representing the "Tempest Mk.I" equipped with the Napier Sabre IV engine; this flight had been principally delayed by protracted problems and slippages encountered in the development of the new Sabre IV engine.<ref name=Thomas106/> Construction had been on hold (so parts could be used for possible repairs to the first prototype) until ''HM595'' was converted to Sabre II.<ref name=":0" /> ''HM599'' was at first equipped with the older Typhoon cockpit structure and vertical tailplane. The elimination of the "chin" radiator did much to improve overall performance, leading to the Tempest Mk.I quickly becoming the fastest aircraft that Hawker had built at that time, having attained a speed of {{convert|466|mph|km/h|abbr=on}} during test flights.<ref name=Mason91_332/> The Sabre IV was failing testing and so the Mk I Tempest was abandoned by the MAP.<ref>Buttler 2004 p21</ref> 

On 27 November 1944, the Tempest Mk.III prototype, ''LA610'', conducted its first flight; it was decided to discontinue development work on the Mk.III, this was due to priority for the Griffon engine having been assigned to the [[Supermarine Spitfire (Griffon-powered variants)|Supermarine Spitfire]] instead.<ref name=Mason67_4_6/>{{#tag:ref|''LA610'' went on to serve as the prototype for the later [[Hawker Sea Fury|Hawker Fury/Sea Fury]], what would be the ultimate offshoot of the Typhoon and Tempest family as well as the fastest of all Hawker-built piston-engine fighters.<ref name=Mason67_6>Mason 1967, p. 6.</ref>|group=nb}}  The Air Ministry had seen the Mk III as a replacement for the Hurricane in ground attack, with the narrower engine giving a better view as well but the Typhoon would be the interim aircraft for the role. In practice the Typhoon proved very good for ground attack.<ref>Buttler, 2004 p 20</ref>

Work on the Tempest Mk.IV variant was abandoned without any prototype being flown at all.<ref name="Mason67_4_6" /> The Tempest Mk.II, which was subject to repeated delays due to its Centaurus powerplant, was persisted with, but would not reach production in time to see service during the Second World War.<ref name="Mason67_6" /> Continual problems with the Sabre IV meant that only the single Tempest Mk.I (''HM599'') was built; consequently, Hawker proceeded to take the Sabre II-equipped "Tempest V" into production instead.<ref name="Thomas107">Thomas and Shores 1988, p. 107.</ref>

In August 1942, even before the first flight of the prototype Tempest V had been conducted, a production order for 400 Tempests was placed by the Air Ministry.<ref name="Mason67_5">Mason 1967, p. 5.</ref>{{Efn|At the start of March 1942, the contract had been for 400 Mark I<ref>Buttler 2004 p 20</ref>}} This order was split, with the initial batch of 100 being Tempest V "Series I"s, powered by the {{convert|2,235|hp|kW|abbr=on}} Sabre IIA series engine, which had the distinctive chin radiator, while the rest were to have been produced as the Tempest I, equipped with the Sabre IV and leading-edge radiators. These 300 Tempest Is were intended to replace an order for a similar quantity of Typhoons placed with the [[Gloster Aircraft Company]].<ref name="Mason67_5" />{{#tag:ref|It had been intended that prefabricated Typhoon components could be reused on the Tempest, this proved to be impractical as the design production Tempest had diverged considerably from the Typhoon.<ref name=Mason67_5/>|group=nb}} As it transpired, the difficulties with the Sabre IV and the wing radiators led to this version never reaching production, the corresponding order was switched to 300 Tempest V "Series 2"s instead.<ref name="Mason67_5" /><ref name="Ovc1">Ovčáčík and Susa 2000, p. 1.</ref>{{#tag:ref|Although JNxxx serialled Tempest Vs are called "Series 1" and later ones called "Series 2", these definitions first appeared in 1957, and there is room for doubt about them being used by Hawker during the Second World War.<ref>[http://www.rafcommands.com/forum/showthread.php?s=3b945437fb56fc153bd6de6c7f848d7d&t=460 "Discussion on first 100 Tempest V."] ''rafcommands.com.'' Retrieved: 1 January 2012.</ref>|group=nb}}