View source for Engineering:Hawker Hart

{{Short description|1928 bomber airplane family by Hawker}}
{|{{Infobox aircraft begin
  |name = Hart
  |image = File:Camm hart 500.jpg
  |caption = Hawker Hart ''G-ABMR''
}}{{Infobox aircraft type
  |type = Light bomber
  |manufacturer = Hawker Aircraft Limited
  |designer = [[Biography:Sydney Camm|Sydney Camm]]
  |first flight = June 1928
  |introduced =1930
  |retired = 1943
  |status = 
  |primary user = {{wipe|Royal Air Force}}<!--please list only one-->
  |more users = <!--up to three more. please separate with <br/>.-->
  |produced = <!--years in production, e.g. 1970-1999, if still in active use but no longer built-->
  |number built = 
  |unit cost = 
  |variants with their own articles = [[Engineering:Hawker Hind|Hawker Hind]] <br> [[Engineering:Hawker Hector|Hawker Hector]]
}}
|}

The '''Hawker Hart''' is a British two-seater [[Engineering:Biplane|biplane]] light bomber aircraft that saw service with the {{wipe|Royal Air Force}} (RAF). It was designed during the 1920s by [[Biography:Sydney Camm|Sydney Camm]] and manufactured by Hawker Aircraft. The Hart was a prominent British aircraft in the inter-war period, but was obsolete and already side-lined for newer [[Engineering:Monoplane|monoplane]] aircraft designs by the start of the Second World War, playing only minor roles in the conflict before being retired.

Several major variants of the Hart were developed, including a navalised version for the Royal Navy's [[Engineering:Aircraft carrier|aircraft carrier]]s. Beyond Britain, the Hart would be operated by a number of foreign nations, including Sweden, [[Place:Yugoslavia|Yugoslavia]], Estonia, {{wipe|South Africa}}, and Canada.

==Design and development==
In 1926, the Air Ministry stated a requirement for a two-seat high-performance light day-bomber, to be of all-metal construction and with a maximum speed of 160&nbsp;mph (258&nbsp;km/h). Designs were tendered by Hawker, [[Company:Avro|Avro]] and de Havilland.<ref>Lewis 1974, p. 146.</ref> Fairey, who had sold a squadron's worth of its wooden [[Engineering:Fairey Fox|Fox]] bomber in 1925, was not at first invited to tender to the specification, and was sent a copy of the specification only after protesting to the Chief of the Air Staff, Hugh Trenchard.<ref name="Jarret May95 p13">Jarrett ''Aeroplane Monthly'' May 1995, p. 13.</ref><ref name="Fairey p196">Taylor 1974, p. 196.</ref>

Hawker's design was a single-bay [[Engineering:Biplane|biplane]] powered by a Rolls-Royce F.XI water-cooled V12 engine (the engine that later became known as the Rolls-Royce Kestrel). It had, as the specification required, a metal structure, with a fuselage structure of steel-tube covered by [[Chemistry:Aluminium|aluminium]] panels and fabric, with the wings having steel spars and [[Chemistry:Duralumin|duralumin]] ribs, covered in fabric. The crew of two sat in individual tandem cockpits, with the pilot sitting under the wing trailing edge, and operating a single .303&nbsp;in (7.7&nbsp;mm) [[Engineering:Vickers machine gun|Vickers machine gun]] mounted on the port side of the cockpit. The observer sat behind the pilot, and was armed with a single [[Engineering:Lewis gun|Lewis gun]] on a ring mount, while for bomb-aiming, he lay prone under the pilot's seat.<ref name="Jarrett Jun95 p30-2">Jarrett ''Aeroplane Monthly'' June 1995, pp. 30–32.</ref> Up to 520&nbsp;pounds (240&nbsp;kg) of bombs could be carried under the aircraft's wings.<ref name="Mason Hawker p170">Mason 1991, p. 170.</ref>

The prototype Hart, [[Engineering:United Kingdom military aircraft serial numbers|serial]] ''J9052,'' first flew in June 1928, being delivered to the Aeroplane and Armament Experimental Establishment at RAF Martlesham Heath on 8 September. It demonstrated good performance and handling, reaching 176&nbsp;mph (283&nbsp;km/h) in level flight and {{convert|282|mph|km/h}} in a vertical dive.<ref name="Jarrett May95 p14">Jarrett ''Aeroplane Monthly'' May 1995, p. 14.</ref><ref name="Mason Bomber p205">Mason 1994, p. 205.</ref> The competition culminated in the choice of the Hawker Hart in April 1929. The de Havilland Hound was rejected due to handling problems during landing and because of its part-wooden primary structure. While the [[Engineering:Avro Antelope|Avro Antelope]] demonstrated similar performance and good handling, the Hart was preferred as it was far cheaper to maintain, a vital aspect to a programme during defence budget constraints that the British armed forces faced during the 1920s. The [[Engineering:Fairey Fox|Fairey Fox IIM]] (which despite the name was a new aircraft), delayed by Fairey's late start on the design compared to the other competitors, only flew for the first time on 25 October 1929, long after the Hart had been selected.<ref name="Jarrett May95 p14"/>

A total of 992 aircraft were built as Harts.<ref name="Mason Bomber p207"/>{{#tag:ref|This excludes the six Hart Fighters, later re-designated Demon, but includes the prototype Audax, Osprey, Demon and Hardy, which were converted Harts.<ref name="Mason Bomber p207"/>|group=N}}  It became the most widely used light bomber of its time and the design would prove to be a successful one with a number of derivatives, including the [[Engineering:Hawker Hind|Hawker Hind]] and [[Engineering:Hawker Hector|Hector]]. There were a number of Hart variants, though only slight alterations were made to the design. The ''Hart India'' was a tropical version, the ''Hart Special'' was a tropical Hawker Audax, a Hart variant with desert equipment; a specialised ''Hart Trainer'' was also built which dispensed with the gunner's ring. Vickers built 114 of the latter model at Weybridge between 1931 and June 1936.<ref>Lewis 1974, pp. 176, 233.</ref>

The production Hart day bomber had a 525&nbsp;hp (390&nbsp;kW) Rolls-Royce Kestrel IB 12-cylinder V-type engine; a speed of 184&nbsp;mph (296&nbsp;km/h) and a range of 470&nbsp;mi (757&nbsp;km).<ref name="Jarrett Jun95 p32"/> It was faster than most contemporary fighters, an astonishing achievement considering it was a light bomber. It also enjoyed excellent manoeuvrability, making the Hart one of the most effective biplane bombers ever produced for the Royal Air Force. In particular, it was faster than the Bristol Bulldog, which had recently entered service as the RAF's front line fighter. This disparity in performance led the RAF to gradually replace the Bulldog with the [[Engineering:Hawker Fury|Hawker Fury]].<ref>Lewis 1974, p. 176.</ref>

Demand was such that production was spread out among a wide selection of aircraft companies. Of the 962 built in the United Kingdom, Hawker produced 234, [[Company:Armstrong Whitworth|Armstrong Whitworth]] 456, Gloster 46, Vickers 226 and 42 were produced in Sweden under licence by ASJA who built 18, Götaverken who built three and the Central Workshops of the Air Force (CVM) who built 21.<ref name="aeroflight.co.uk">[http://www.aeroflight.co.uk/aircraft/types/hawker-hart.htm "Hawker Hart."] ''aeroflight.co.'' Retrieved: 4 December 2012.</ref> 1004 Harts were produced.<ref name="aeroflight.co.uk"/>

==Operational history==
The Hart entered service with No. 33 Squadron RAF in February 1930, replacing the larger and slower [[Engineering:Hawker Horsley|Hawker Horsley]]. No. 12 Squadron replaced its Foxes with Harts in January 1931, with a further two British-based Hart light bomber squadrons forming during 1931.<ref name="Thetford July95 p51">Thetford ''Aeroplane Monthly'' July 1995, p. 51.</ref>

Harts were deployed to the Middle East during the Abyssinia Crisis of 1935–1936. The Hart saw extensive and successful service on the North-West Frontier, British India during the inter-war period. Four Hawker Harts from the {{wipe|Swedish Air Force}} saw action as dive bombers during the 1939–1940 Winter War as part of a Swedish volunteer squadron, designated F19, fighting on the Finnish side. Though obsolete compared to the United Kingdom's opposition at the start of the [[Social:World War II|Second World War]], the Hart continued in service, mainly performing in the communications and training roles until being declared obsolete in 1943.<ref>Lewis 1974, p. 233.</ref>

The Hart proved to be a successful export, seeing service with the Royal {{wipe|Egyptian Air Force}}, Royal {{wipe|Indian Air Force}}, {{wipe|South African Air Force}}, {{wipe|Estonian Air Force}}, Southern Rhodesia, Sweden (where it was designated B4) and the Kingdom of Yugoslavia. The Rhodesian Hardys saw service on the Allied side during the opening moves of the East African theatre of World War II.

Swedish Air Force General Björn Bjuggren wrote in his memoirs<ref>Bjuggren, Björn (1965). Attack: minnen från trettiofem års flygtjänst (in Swedish). Stockholm: Norstedt.</ref> how his squadron developed dive-bombing techniques in the mid-1930s for their B4s.{{#tag:ref|Bjuggren claims that he got this idea from watching a Hollywood movie with dive bombers.|group=N}} When the Hawker engineers found out, they issued a formal objection, saying that the aircraft had not been designed for that purpose. However, the Swedish pilots proved that the aircraft was up to the task and dispelled their concerns.<ref>Lewis 1974, p. 224.</ref>

==Variants==

===Hart===
;Hart I
:Two-seat light bomber aircraft for the RAF. 525&nbsp;hp Kestrel IB engine.<ref name="Mason Hawker p488">Mason 1991, p. 488.</ref>
;Hart SEDB
:Two-seat single-engined light bomber aircraft for the RAF, powered by a 525&nbsp;hp Rolls-Royce Kestrel IB, or a 510&nbsp;hp Kestrel X (DR) piston engine.<ref name="Mason Hawker p492">Mason 1991, p. 492.</ref>
;Hart (India)
:Tropicalised version for the RAF, used by RAF in the North West Frontier of India, with larger radiator and extra equipment.<ref name="Jarrett May95 p15">Jarrett ''Aeroplane Monthly'' May 1995, p. 15.</ref>
;Hart (C)
:Two-seat unarmed communications aircraft for the RAF, a small number were used by No. 24 Squadron RAF; eight built.<ref name="Mason Hawker p,490,494">Mason 1991, pp. 490, 494.</ref>
;Hart Trainer (Interim)
:Hart light bombers converted into training aircraft. Two built.<ref name="Mason Hawker p160">Mason 1991, p. 160.</ref>
;Hart Trainer
:Two-seat dual-control trainer aircraft, with reduced sweepback on top wings to compensate for movement in center of gravity caused by removal of military equipment.<ref name="Mason Hawker p161">Mason 1991, p. 161.</ref>
;Hart Fighter
:Two-seat fighter version for the RAF used by No. 23 Squadron RAF, with Kestrel IIS. Later redesignated as the ''Demon''; six built.<ref name="Mason Hawker p489">Mason 1991, p. 489.</ref>
;Hart (Special)
:Tropicalised version for the RAF, used by the RAF in the Middle East. Based on Audax airframe with desert equipment, and de-rated Kestrel X engine.<ref name="Wixey AE97 p57-8">Wixey ''Air Enthusiast'' January/February 2002, pp. 57–58.</ref><ref name="Mason Hawker p159">Mason 1991, p. 159.</ref>
;Hart (Testbeds)
:Several Harts were used as engine testbeds, including ''G-ABMR'' and ''G-ABTN'' which were used to test several variants of Kestrel engines. ''K2434'' was used by Napier to test the Napier Dagger I, II and III. ''K3036'' was used by Rolls-Royce to test the Merlin C and E, complete with a ventral radiator.<ref>Mason 1991, pp. 166–170.</ref>
;Estonian Hart
:Export version for Estonia, equipped with an interchangeable wheel or float undercarriage; eight built.<ref name="Mason Hawker p165">Mason 1991, p. 165.</ref><ref name="Wixey AE96 p28-9">Wixey ''Air Enthusiast'' November/December 2001, pp. 28–29.</ref>
[[File:Hawker Hart, B 4.jpg|thumb|A preserved Hart of the Swedish Air Force, powered by a Bristol Pegasus radial engine, in Finnish Air Force markings (1976)]]
;Swedish Hart
:Light bomber for Swedish Air Force. Four Hawker-built pattern aircraft, powered by a Bristol Pegasus IM2 radial piston engine were delivered in 1934. Following successful evaluation, 42 were built under licence in Sweden by AB Götaverken of Göteborg, powered by a Swedish-built NOHAB Pegasus IU2.<ref name="Mason Hawker p165"/><ref name="Wixey AE96 p28-9"/>

===Audax===

The ''Hawker Audax'' was a Hart variant, designed for army cooperation, seeing much service in the [[Place:British Empire|British Empire]]. The first Audax flew in late 1931 and over 700 Audaxes were produced (including export). The Audax was similar to the Hart, though had some modifications, including a hook to pick up messages.<ref name="Smith">{{cite book |last1=Smith |first1=Peter |title=Combat Biplanes of World War II |date=2014 |publisher=Pen & Sword |location=United Kingdom |isbn=978-1783400546 |pages=501}}</ref> It was armed with a single Scarff ring-mounted .303&nbsp;in (7.7&nbsp;mm) [[Engineering:Lewis gun|Lewis gun]] and a fixed forward-firing .303&nbsp;in (7.7&nbsp;mm) [[Engineering:Vickers machine gun|Vickers machine gun]]<ref name="Smith" /> and was powered by a version of the Kestrel engine and had a maximum speed of {{convert|170|mph|km/h|sigfig=3|abbr=on}}. A number of variants of the Audax were produced, including the ''Audax India'', a tropicalised version of the Audax for service in India and the ''Audax Singapore'' for service there.<ref>[http://www.211squadron.org/audax___hind.html "Hawker Audax and Hawker Hind."] ''211squadron.org''. Retrieved: 13 July 2013.</ref>

[[File:HAudax.jpg|thumb|Audax prototype]]
Other air forces which also used the Audax included the {{wipe|Royal Canadian Air Force}}, the {{wipe|Royal Indian Air Force}}, the {{wipe|South African Air Force}}, the Royal Egyptian Air Force, the Royal Iraqi Air Force, the {{wipe|History of the Iranian Air Force}}, the Straits Settlements and the {{wipe|Southern Rhodesian Air Force}}. During the Second World War the Audax saw limited service in Africa on the Kenya–Abyssinia border during the Second Italo-Ethiopian War.<ref name="Smith" /> The Audax also saw service in Iraq, at RAF Habbaniya, west of [[Place:Baghdad|Baghdad]], after the uprising there, during the Anglo-Iraqi War. In the days leading up to that battle crews began to upgrade the Audaxes stationed there, despite having received orders forbidding such actions. They fitted some to carry {{convert|250|lb|kg|sigfig=3|abbr=on}} bombs instead of {{convert|20|lb|kg|sigfig=1|abbr=on}} bombs.<ref name="Smith" />

The Audax ended its service by 1945. A derivative of the Audax, the ''Hawker Hartebeest'', a light bomber, was built for the South African Air Force with modifications made from the Audax. Sixty-nine of these aircraft were built, the majority in South Africa.<ref>{{cite web |title=Hawker Hartbees |publisher=BAE Systems |url=https://www.baesystems.com/en-uk/heritage/hawker-hartbees |access-date=24 January 2024}}</ref> The aircraft saw action in East Africa during clashes against Italy who occupied Abyssinia.<ref>Arthur, Max. ''Lost Voices of the RAF.'' London: Hodder & Stoughton, 20055. {{ISBN|978-0-34083-813-6}}.</ref>

[[File:Hawker Audax K3077 26 Sq BTN 08.09.34 edited-2.jpg|thumb|Audax of 26 Squadron in 1934]]
A.V. Roe built 287 Audaxes as part of the RAF expansion scheme during 1935–1937. These did not warrant an Avro type number but between 1937 and 1938, Avro built 24 modernised Audaxes for the Egyptian government, powered by {{convert|750|hp|kW|sigfig=2|abbr=on}} Armstrong Siddeley Panther VIA radials. Acknowledging the amount of redesign work done, these were designated the ''Avro Type 674''.

'''Audax I'''
:Two-seat army cooperation aircraft for the RAF, powered by a 530&nbsp;hp (395&nbsp;kW) Rolls-Royce Kestrel IB, or 580&nbsp;hp Kestrel X piston engine.
'''Audax''' (India)
:Tropicalised version for the RAF, used by the RAF in India.
'''Audax''' (Singapore)
:Tropicalised version for the RAF, powered by a Rolls-Royce Kestrel V piston engine, used by the RAF in Singapore and British Malaya.
'''Canadian Audax'''
:Modified version of the Audax I for the RCAF; one built for Canada.
'''Egyptian Audax'''
:Six aircraft fitted with the 750 hp Armstrong Siddeley Panther radial piston engine, plus 18 aircraft fitted with the Panther X radial piston engine; 34 built for Egypt.
'''Iraqi Audax''' (Nisr)
:24 aircraft fitted with the Bristol Pegasus IIM2 radial piston engine, plus ten aircraft fitted with the Pegasus VIP8 radial piston engine; 34 built for Iraq.<ref>{{cite news |url=http://nla.gov.au/nla.news-article32804842 |title=MOTORING. |newspaper=The West Australian |location=Perth |date=8 November 1934 |access-date=16 August 2013 |page=7 |publisher=National Library of Australia}}</ref>
'''Persian Audax'''
:30 aircraft fitted with the Pratt & Whitney Hornet S2B radial piston engine, plus 26 aircraft fitted with the Bristol Pegasus IIM or IIM2 radial piston engine; 56 built for Persia.
{{anchor|Hartebeest}}
'''Hartebeest'''
:Hawker-built pattern aircraft; 4 built and exported to South Africa.
'''Hartebeest I'''
:Two-seat general-purpose, ground support aircraft for the South African Air Force, powered by a 608&nbsp;hp (453&nbsp;kW) Rolls-Royce Kestrel VFP piston engine; 4 aircraft built by Hawker Aircraft in the UK, 65 aircraft built under licence by SAAF Roberts Heights Depot, Pretoria, in South Africa.

===Demon===

[[File:Hawker Demon I K8200 64 Sqn RWY 25.06.38 edited-2.jpg|thumb|Boulton Paul built Demon I of 64 Squadron in 1938]]
The Hawker Demon was a fighter variant of the Hart light bomber. During air defence exercises the RAF's Siskins and Bulldogs were often unable to intercept the new Hart bombers, which were sometimes instructed to restrict their height and speed in order to give the fighters a chance, which prompted the development of a fighter variant of the Hart.<ref name="Thetford July95 p56">Thetford ''Aeroplane Monthly'' July 1995, p. 56.</ref>

While the [[Engineering:Hawker Fury|Hawker Fury]] offered better performance, lower production volumes made it more expensive and therefore it remained available only in small numbers, so when a fighter version of the Hart was suggested, the Air Ministry selected the type as an interim fighter until higher-performance fighters could be bought in larger numbers.<ref name="Mason Fighter p234">Mason 1992, p. 234.</ref> The new fighter variant added a second Vickers machine gun, while the coaming of the rear cockpit was angled to give a better field of fire, and a [[Engineering:Supercharger|supercharged]] Kestrel IS engine was fitted. Evaluation of an initial batch of six aircraft, known as Hart Fighters by one flight of 23 Squadron during 1931 was successful, and larger orders followed for the fighter Hart, now known as the Hawker Demon.<ref name="Mason Hawker p219">Mason 1991, p. 219.</ref> The production Demon's first flight was on 10 February 1933.<ref name="am1091p588">Lumsden ''Aeroplane Monthly'' October 1991, p. 588</ref>

305 Hawker Demons were built, including 232 for the RAF.<ref>{{cite web|url=http://www.historyofwar.org/articles/weapons_hawker_demon.html|title=Hawker Demon|website=www.historyofwar.org}}</ref> The Demon was powered by versions of the Kestrel engine. It had an armament of a single rear .303&nbsp;in (7.7&nbsp;mm) Lewis Gun with two fixed .303&nbsp;in (7.7&nbsp;mm) Vickers machine guns in the nose. Many were fitted with a hydraulically-powered turret in the rear gunner's position, which had been tested on the Hawker Hart. Demons were also sold to the {{wipe|Royal Australian Air Force}}. It saw only second-line operations during the Second World War.

[[File:Hawker Demon ExCC.jpg|thumb|Hawker Demons of No. 23 Squadron RAF]]
Production of the Demon was undertaken by Hawker and by Boulton Paul Aircraft at their Wolverhampton factory, where their last example of 106 to be completed was delivered to the RAF in December 1937.

;Hart two-seat fighter
:Two-seat fighter version of the Hart for the RAF. Later redesignated as the ''Hart Fighter''.
;Demon I
:Two-seat fighter aircraft for the RAF.
;Australian Demon I
:Two-seat fighter aircraft for the RAAF, similar to RAF version but fitted with a 600&nbsp;hp (447&nbsp;kW) Rolls-Royce Kestrel V engine; 54 built (the first 18 delivered as general-purpose fighters in 1935 and an additional 36 for army co-operation duties delivered in 1936).
;Australian Demon II
:Two-seat training version for the RAAF, standard Demon fitted with dual controls and provision for target towing, 10 built
;Turret Demon
:Two-seat fighter version, fitted with a Frazer-Nash gun turret in the rear cockpit.

===Hardy===
[[File:Hawker Hardy LOC matpc.18774.jpg|thumb|Hawker Hardy aircraft operating from RAF Ramleh airfield in the 1930s]]
The ''Hawker Hardy'' was a general-purpose variant of the ''Hawker Hart'' tropicalised to meet Air Ministry Specification G.23/33 as a Wapiti replacement in Iraq. The prototype was a production Hart which was modified with a modified radiator, a message pick-up hook, water containers and a desert survival kit. The prototype first flew on 7 September 1934, and the first production aircraft were delivered to 30 Squadron in January 1935. The ''Hardy'' saw some service during the Second World War, in Africa and the Middle East; the ''Hardys'' performing a number of operations against Italian-occupied Abyssinia as well as other areas of Africa. The ''Hardy'' also saw service with Southern Rhodesia. The last operational sortie by a Hardy was on 9 May 1941 and most of the survivors were scrapped, although some continued in service as communications aircraft. On 14 May 1941, the Belgian Colonial authorities obtained a Hawker Hardy from the South African Air Force. Painted in Belgian colours, the machine was used for observation missions, but unfortunately overturned while landing at Gambela airfield on 26 May 1941, effectively writing off the aircraft.

;Hardy I
:Two-seat general-purpose aircraft for the RAF, 47 built excluding one prototype modified from a Hart

===Hind===
{{main|Engineering:Hawker Hind}}
[[File:HawkerHindShuttleworth2004.jpg|thumb|Hawker Hind, flying example in Shuttleworth Collection]]
[[File:Hawker Hind K5414 (Shuttleworth Uncovered).jpg|thumb|Hawker Hind (Afghan) flying at Old Warden]]

The ''Hawker Hind'' was a derivative of the Hart and was intended to replace it. The [[Engineering:Hawker Hector|Hawker Hector]] was a variant of the Hind and was used in the army co-operation role. It saw only limited service during the Second World War with the Royal Air Force. Hectors were also sold to Ireland.

===Osprey===
[[File:HMS Enterprise 1936 LOC matpc 20251.jpg|thumb|A Hawker Osprey IV on the catapult of the cruiser {{HMS|Enterprise|D52|6}} in 1936]]
[[File:Hawker Osprey.jpeg|thumb|A Swedish Osprey ready to launch from the cruiser {{HSwMS|Gotland|1933|6}}]]

The ''Hawker Osprey'' was the navalised carrier-borne version of the Hart, performing in the fighter and reconnaissance roles. The Osprey had a single Rolls-Royce Kestrel II engine, and had a max speed of 168&nbsp;mph (270&nbsp;km/h). Its armament consisted of a single forward .303&nbsp;in (7.7&nbsp;mm) Vickers machine gun and one .303&nbsp;in (7.7&nbsp;mm) Lewis gun. The Osprey joined the Fleet Air Arm (FAA) in 1932, with 103 being built, and ended its career in 1944 after serving as a trainer for FAA pilots during the Second World War. By December 1936, Ospreys were being deployed by 701 Squadron based at RAF Kalafrana in the anti-submarine and anti-piracy role. The Osprey was also sold to the {{wipe|Swedish Air Force}} being used on the seaplane cruiser {{HSwMS|Gotland|1933|6}}, which carried six Ospreys. Ospreys were also sold to the Portuguese Naval Aviation and the {{wipe|Spanish Republican Air Force}}.

;Osprey I
:Two-seat fleet spotter and reconnaissance aircraft, powered by a 630&nbsp;hp (470&nbsp;kW) Rolls-Royce Kestrel IIMS inline piston engine; 37 built.
;Osprey II
:Two-seat fleet spotter and reconnaissance aircraft, powered by a 630&nbsp;hp (470&nbsp;kW) Rolls-Royce Kestrel IIMS piston engine, equipped with redesigned floats; 14 built.
;Osprey III
:Two-seat fleet spotter and reconnaissance aircraft, powered by a 630&nbsp;hp (470&nbsp;kW) Rolls-Royce Kestrel IIMS piston engine, equipped with a dinghy stowed away in the starboard upper wing; 26 built.
;Osprey IV
:Two-seat fleet spotter and reconnaissance aircraft, powered by a 640&nbsp;hp Rolls-Royce Kestrel V.<ref name="Marriott2010p296">{{Harvnb|Marriott|2010|p=296.}}</ref> Twenty-six built in 1935.<ref name="Mason Hawker p228">Mason 1991, p. 228.</ref>
;Portuguese Osprey
:Two aircraft equivalent to Osprey III built for Portugal and powered by Kestrel IIMS piston engine. Delivered in 1935. Six aircraft more in 1939.<ref name="Mason Hawker p228"/><ref name="Wixley AE97 p63"/>
;Spanish Osprey
:One aircraft fitted with a Hispano-Suiza 12Xbrs engine; one built for the {{wipe|Spanish Republican Air Force}}.
;Swedish Osprey
:Version for Sweden fitted with a {{convert|600|hp|kW}} Swedish-built NOHAB Bristol Mercury radial piston engine and interchangeable wheel and float landing gear. Six built. Given the designation ''S 9'' by the {{wipe|Swedish Air Force}}.<ref name="Wixley AE97 p63">Wixley ''Air Enthusiast'' January/February 2002, p. 63.</ref><ref name="hybrid p41-2">Layman and McLaughlin 1991, pp. 41–42.</ref>

==Operators==
[[File:Hawker Hart G-ABMR CVT 19.06.54 edited-3.jpg|thumb|Hawker Aircraft's demonstrator Hart airworthy in 1954 painted in their dark blue house colours]]

===Hawker Hart===
*{{flag|Kingdom of Afghanistan|name=Afghanistan}}
*{{flag|Canada|1921}}
*{{flag|Egypt|1922}}
*{{EST}}
*{{flag|British India}}
*{{flag|Iran|1925|name=Persia}}
*{{flag|South Africa|1928}}
*{{flag|Southern Rhodesia}}
*{{SWE}}
*{{flagu|United Kingdom}}
*{{flag|Kingdom of Yugoslavia}}

===Hawker Audax===
*{{flag|British India}}
*{{flag|Canada|1921}}
*{{flag|Egypt|1922}}
*{{flag|Iraq|1924}} - No. 3 Squadron IqAF<ref name=MalovanyAF>Pesach Malovany, "Wars of Modern Babylon", University Press of Kentucky, June 2017, {{ISBN|0813169437}} / {{ISBN|978-0813169439}}, fn. 2, p.813.</ref>
*{{flag|Iran|1925|name=Persia}}
*{{flag|Southern Rhodesia}}
*{{flag|Straits Settlements}}
*{{flagu|United Kingdom}}

===Hawker Demon===
*{{flagu|Australia}}
*{{flagu|United Kingdom}}

===Hawker Hardy===
*{{flagu|United Kingdom}}
*{{flag|Southern Rhodesia}}
*{{BEL}} (one aircraft, ex-RAF K4316)
*{{flag|Belgian Congo}}

===Hawker Hartebeest===
*{{flag|South Africa|1928}}

===Hawker Osprey===
*{{POR}}
*{{flag|Spanish Republic}}
*{{SWE}}
*{{flagu|United Kingdom}}

==Surviving aircraft==
[[File:Hawker Hart II RAF Museum.jpg|thumb|Hawker Hart II ''G-ABMR'', RAF Museum (2007)]]
[[File:Hawker Demon K8203 (Suttleworth uncovered).jpg|thumb|Demon I, Shuttleworth Collection]]

;Australia
* A1-8 – Demon I on static display at the RAAF Museum in Point Cook, Victoria. Delivered 1935, served with No. 3 Squadron RAAF until 1937 when it was wrecked in Tasmania and reduced to components. Restored 1987 by 2AD in Richmond, New South Wales.<ref>{{cite web |last1=McGuiness |first1=Paul |last2=Crick |first2=Darren |last3=Cowan |first3=Brendan |title=RAAF A1 Hawker Demon Mk.I & Mk.II |url=http://www.adf-serials.com.au/2a1.htm |website=ADF Serials |access-date=24 November 2018 |date=29 November 2017}}</ref>

;Sweden
* 714 – B 4 on static display at the {{wipe|Swedish Air Force Museum}} near Linköping, Östergötland.<ref>{{cite web |title=B 4 |url=https://www.flygvapenmuseum.se/samlingar/flygplan/flygvapenmuseum-linkoping/b-4---hawker-hart |website=Flygvapenmuseum |access-date=24 November 2018 |language=sv}}</ref>

;United Kingdom
* G-ABMR – Hart II on static display at the Royal Air Force Museum London in [[Place:London|London]]. The 13th off the production line, it first flew in 1931 but never saw military use. Under the civilian registration ''G-ABMR'', it was used by Hawker in various roles, including testbed, demonstration aircraft and a camera aircraft. It flew throughout the Second World War and continued flying until 1971. Still airworthy, it was then transferred to the RAF Museum, on loan from Hawker Siddeley, Hawker Aircraft's successor company. It remains there, painted to represent RAF Hart serial number ''J9941''.<ref>{{cite web |title=Hawker Hart II |url=http://www.rafmuseum.org.uk/research/collections/hawker-hart-ii |website=Royal Air Force Museum |access-date=24 November 2018}}</ref><ref>{{cite web |last1=Simpson |first1=Andrew |title=INDIVIDUAL HISTORY [G-ABMR] |url=http://www.rafmuseum.org.uk/documents/collections/74-A-29-Hawker-Hart-II-G-ABMR.pdf |website=Royal Air Force Museum |access-date=24 November 2018 |date=2013}}</ref>
* K4972 – Hart Trainer on static display at the {{wipe|Royal Air Force Museum Cosford}} in Cosford, Shropshire. Built in 1935 by Armstrong Whitworth, it flew as a training aircraft before being used as an instructional airframe. In 1943, it passed on to the Air Training Corps unit at Nelson Tomlinson School, Wigton, where it remained until recovered in 1962 by a group of aviation enthusiasts. They passed it on to the RAF Museum in 1962.<ref>{{cite web |title=Hawker Hart Trainer |url=http://www.rafmuseum.org.uk/research/collections/hawker-hart-trainer |website=Royal Air Force Museum |access-date=24 November 2018}}</ref><ref>{{cite web |last1=Simpson |first1=Andrew |title=INDIVIDUAL HISTORY [K4972] |url=http://www.rafmuseum.org.uk/documents/collections/71-A-1415-Hawker-Hart-Trainer-K4972.pdf |website=Royal Air Force Museum |access-date=24 November 2018 |date=2012}}</ref>
* K8203 – Demon airworthy at the Shuttleworth Collection in Old Warden, Bedfordshire.<ref>{{cite web |title=HAWKER DEMON |url=http://www.shuttleworth.org/collection/hawkerdemon |website=Shuttleworth |access-date=24 November 2018}}</ref>

== Specifications Hart  (Kestrel IB-powered day bomber) ==
{{Aircraft specs
|ref=''The British Bomber since 1914''.<ref name="Mason Bomber p207">Mason 1994, p. 207.</ref>
|prime units?=imp
<!--
        General characteristics
-->
|genhide=

|crew=2
|capacity=
|length m=
|length ft=29
|length in=4
|span m=
|span ft=37
|span in=3
|height m=
|height ft=10
|height in=5
|wing area sqm=
|wing area sqft=349.5
|wing area note=
|aspect ratio=<!-- sailplanes -->
|airfoil=RAF 28<ref name="Jarrett Jun95 p32">Jarrett ''Aeroplane Monthly'' June 1995, p. 32.</ref>
|empty weight kg=
|empty weight lb=2530
|empty weight note=
|gross weight kg=
|max takeoff weight lb=4596
|gross weight note=
|fuel capacity={{convert|83|impgal|USgal L|abbr=on}}<ref name="Mason Hawker p170"/>
|more general=
<!--
        Powerplant
-->
|eng1 number=1
|eng1 name=Rolls-Royce Kestrel IB
|eng1 type=water-cooled V12 engine
|eng1 kw=<!-- prop engines -->
|eng1 hp=525<!-- prop engines -->

|prop blade number=<!-- propeller aircraft -->
|prop name=
|prop dia m=<!-- propeller aircraft -->
|prop dia ft=<!-- propeller aircraft -->
|prop dia in=<!-- propeller aircraft -->
|prop note=
<!--
        Performance
-->
|perfhide=

|max speed kmh=
|max speed mph=185
|max speed kts=
|max speed note=at {{convert|13000|ft|m|abbr=on}}
|cruise speed kmh=<!-- if max speed unknown -->
|cruise speed mph=<!-- if max speed unknown -->
|cruise speed kts=
|stall speed mph=45
|stall speed note=<ref name ="ferry pilots notes">"Hawker Hart". ''Air Transport Auxiliary Ferry Pilots Notes''. (reproduction). Elvington, York, UK: Yorkshire Air Museum, 1996. {{ISBN|0-9512379-8-5}}.</ref>
|range km=
|range miles=430
|range nmi=
|endurance=<!-- if range unknown -->
|ceiling m=
|ceiling ft=22800
|climb rate ms=
|climb rate ftmin=
|time to altitude=8 min 30 s to {{convert|10000|ft|m|abbr=on}}
|more performance=
<!--
        Armament
-->
|guns=1 × synchronised forward firing .303 in (7.7&nbsp;mm) [[Engineering:Vickers machine gun|Vickers machine gun]], 1 × .303 in (7.7 mm) Lewis Gun on Scarff ring in rear cockpit. 
|bombs= Up to {{convert|520|lb|kg|abbr=on}} bombs under wings<ref name="Mason Hawker p170"/>
|avionics=
}}

==See also==
{{aircontent|
|related=*[[Engineering:Hawker Hind|Hawker Hind]]
|similar aircraft=
|lists=
* [[Engineering:List of aircraft of World War II|List of aircraft of World War II]]
* List of aircraft of the Spanish Republican Air Force
|see also=
}}

==References==

===Notes===
{{Reflist|group=N}}

===Citations===
{{Reflist|30em}}

===Bibliography===
* {{cite journal |last1=Andersson|first1=Lennart|title=Le Hawker Hart en Suède: pas si neutres que ça! |journal=Avions: Toute l'aéronautique et son histoire |date=June 2003 |issue=123 |pages=4–9 |trans-title=The Hawker Hart in Sweden: Not so Neutral! |language=fr |issn=1243-8650}}
* {{cite journal |last1=Andersson|first1=Lennart|title=Le Hawker Hart en Suède (fin) |journal=Avions: Toute l'aéronautique et son histoire |date=August 2003 |issue=125 |pages=24–33 |trans-title=The Hawker Hart in Sweden (Last Part) |language=fr |issn=1243-8650}}
*{{cite journal |last1=Andersson|first1=Lennart|title=Histoire de l'aéronautique persane, 1921–1941: La première aviation du Chah d'Iran |journal=Avions: Toute l'aéronautique et son histoire |date=July 1998 |issue=76 |pages=2–12 |trans-title=History of the Persian Air Force, 1921–1941: The First Aircraft of the Shah of Iran |language=French |issn=1243-8650}}
*{{cite journal |last1=Andersson|first1=Lennart|title=Round-Out: Aeroflot Audaxes |journal=Air Enthusiast |date=March–April 2001|issue=92|page=79 |issn=0143-5450}}
* Crawford, Alex. ''Hawker Hart Family''. Redbourn, Hertfordshire, UK: Mushroom Model Publications Ltd., 2008. {{ISBN|83-89450-62-3}}.
* Gerdessen, Frederik. "Estonian Air Power 1918 – 1945". ''Air Enthusiast'', No. 18, April – July 1982. pp.&nbsp;61–76. {{ISSN|0143-5450}}.
* Goulding, James and Robert Jones. ''Gladiator, Gauntlet, Fury, Demon'' (Camouflage & Markings 5: RAF Fighter Command Northern Europe, 1936 to 1945). London: Ducimus Books Ltd., 1971. OCLC 872045486
* Hannah, Donald. ''Hawker FlyPast Reference Library''. Stamford, Lincolnshire, UK: Key Publishing Ltd., 1982. {{ISBN|0-946219-01-X}}.
* James, Derek N. ''Hawker: An Aircraft Album No. 5''. New York: Arco Publishing Company, 1973. {{ISBN|0-668-02699-5}} (first published in the UK by Ian Allan in 1972).
* Jarrett, Philip. "By Day and by Night: Hawker Harts and Hinds: Part One". ''Aeroplane Monthly'', May 1995, Vol. 23 No. 5, Issue No 265, pp.&nbsp;12–18. London: IPC. ISSN 0143-7240.
* Jarrett, Philip. "By Day and by Night: Hawker Harts and Hinds: Part Two". ''Aeroplane Monthly'', June 1995, Vol. 23 No. 6, Issue No 266, pp.&nbsp;28–33. London: IPC. ISSN 0143-7240.
* Layman, R. D. and Stephen McLaughlin. ''The Hybrid Warship: The Amalgamation of Big Guns and Aircraft''. London: Conway Maritime Press, 1991. {{ISBN|0-85177-555-1}}.
* Lewis, Peter. ''The British Bomber since 1914 Sixty Years of Design and Development.'' London: Putnam, 1974. {{ISBN|0-370-10040-9}}.
* Lumsden, Alec. "On Silver Wings – Part 13". ''Aeroplane Monthly'', October 1991, Vol. 19 No. 10. pp. 586–590. {{ISSN|0143-7240}}.
*{{wikicite|ref={{harvid|Marriott|2010}}|reference=Marriott, L. ''Battleships''. Sywell, Northamptonshire, UK: Igloo Books, 2010. {{ISBN|978-0-85734-421-2}}.}}
* Mason, Francis K. ''The British Bomber Since 1914''. London: Putnam Aeronautical Books, 1994. {{ISBN|0-85177-861-5}}.
* Mason, Francis K. ''The British Fighter since 1912''. Annapolis, Maryland, USA:Naval Institute Press, 1992. {{ISBN|1-55750-082-7}}.
* Mason, Francis K. ''Hawker Aircraft since 1920.'' London: Putnam Aeronautical Books, 1991. {{ISBN|0-85177-839-9}}.
* Mason, Francis K. ''The Hawker Audax & Hardy'' (Aircraft in Profile 140). Leatherhead, Surrey, UK: Profile Publications, 1966. OCLC 45091982
* Rimell, Raymond Laurence. ''The Hart Family: Hawker Hart and Derivatives'' (Aeroguide Classics Number 5). Chipping Ongar, Essex, UK: Linewrights Ltd., 1989. {{ISBN|0-946958-34-3}}.
* Taylor, H. A. ''Fairey Aircraft since 1915''. London: Putnam, 1974. {{ISBN|0-370-00065-X}}.
* Thetford, Owen. "By Day and by Night: Hawker Hart and Hind": Operational History Part One. ''Aeroplane Monthly'', July 1995, Vol. 24 No. 1, Issue No 267, pp.&nbsp;50–57. London: IPC. ISSN 0143-7240.
* Thetford, Owen. "On silver wings – Part 14". ''Aeroplane Monthly'', November 1991, Vol. 19, No. 11, pp. 650–655, 661. {{ISSN|0143-7240}}.
* Wixey, Ken. "Hart of the Matter: Part One – Hawker's Hart 'Family': The Hart Bomber and the Army Co-Op Audax". ''Air Enthusiast'', No 96, November/December 2001, pp.&nbsp;24–33. Stamford UK:Key Publishing. ISSN 0143-5450
* Wixey, Ken. "Hart of the Matter: Part Two- Hawker's Hart 'Family': Demon, Hart Special, Trainer, Osprey, Hardy". ''Air Enthusiast'', No 97, January/February 2002, pp.&nbsp;54–65. Stamford UK:Key Publishing. ISSN 0143-5450

== External links ==


[[Category:Biplanes]]
[[Category:Single-engined tractor aircraft]]

{{Sourceattribution|Hawker Hart}}