View source for Armstrong Whitworth Siskin

{{Short description|Former fighter aircraft}}
{{Use dmy dates|date=August 2017}}
{{Use British English|date=August 2017}}
{{Infobox aircraft
 |name=Siskin
 |image=Siskins.jpg
 |caption = "The Siskins" flight demonstration team
 |type=Fighter
 |manufacturer=[[Armstrong Whitworth Aircraft|Sir W.G. Armstrong Whitworth Aircraft Limited]]
 |designer=F.M. Green
 |first_flight=May 1919 as ''Siddeley-Deasy S.R.2 Siskin''<ref name="mason fighter p149"/>
 |introduction=1923
 |retired=1932
 |primary_user=[[Royal Air Force]]
 |more_users=[[Royal Canadian Air Force]] <br/> [[Royal Swedish Air Force]]
 |produced=<!--years in production, e.g. 1970-1999, if still in active use but no longer built-->
 |number_built=485<ref name="Tapper p140">Tapper 1988, p. 140.</ref>
 |variants=[[Armstrong Whitworth Starling]]
}}

The '''Armstrong Whitworth Siskin''' was a [[sesquiplane]] single-seat [[fighter aircraft]] developed and produced by the British aircraft manufacturer [[Armstrong Whitworth Aircraft]]. It was also the first all-metal fighter to be operated by the [[Royal Air Force]] (RAF), as well as being one of the first new fighters to enter service following the end of the [[World War I|First World War]].

Development of the Siskin was heavily influenced by [[List_of_Air_Ministry_specifications#RAF_specifications_(1918–1920)|RAF Specification Type I]], including its initial use of the [[ABC Dragonfly]] [[radial engine]]. Making its first flight in May 1919, the Siskin possessed good qualities in spite of the Dragonfly's poor performance. In the following year, the much better [[Armstrong Siddeley Jaguar]] was installed and flight with this powerplant was made on 20 March 1921. In response to [[List_of_Air_Ministry_specifications#RAF_specifications_(1918–1920)|Air Ministry Specification 14/22]], the aircraft was redesigned with an all-metal structure, and orders were placed in 1922.

In May 1924, the first of the RAF's Siskin IIIs were delivered to [[No. 41 Squadron RAF|No. 41 Squadron]] at [[RAF Northolt]]. Eleven squadrons would operate the type. Relatively popular with pilots, it served for over eight years before the last of them were replaced by [[Bristol Bulldog]]s during October 1932. In addition to the RAF, various other nations evaluated the Siskin and several placed orders. The [[Royal Canadian Air Force]] (RCAF)  introduced the type in the late 1920s and operated its Siskins until shortly after the outbreak of the [[World War II|Second World War]]. Several Siskins were also entered in various [[air racing|air races]].

==Development==
===Background===
The Armstrong Whitworth Siskin was a development of the Siddeley-Deasy S.R.2 Siskin designed by Major [[F. M. Green]] (formerly chief engineer of the [[Royal Aircraft Factory]]) of the [[Siddeley-Deasy]] Motor Car Company.<ref name="mason fighter p148"/> A major impetus for the aircraft's development was the [[Air Ministry]]'s issuing of [[List_of_Air_Ministry_specifications#RAF_specifications_(1918–1920)|RAF Specification Type I]], which called for a single-seat fighter that was powered by the [[ABC Dragonfly]] [[radial engine]]. The Dragonfly would prove to be a disappointment as it failed to meet its anticipated performance.<ref name="mason fighter p148">Mason 1992, p. 148.</ref><ref name="Tapper p117">Tapper 1988, p. 117.</ref>

The SR.2 Siskin was a single-[[interplane strut|bay]] [[biplane]] of wood and fabric construction. It was angular in form, with little attention paid to obvious avenues for [[Aerodynamic drag|drag]] reduction.<ref name="Tapper p123"/> Perhaps its most distinctive feature was its fixed [[conventional landing gear]], which had relatively lengthy [[oleo strut]] [[shock absorber]]s carrying the [[axle]], which was in turn connected by [[radius rod]]s to a pair of V-struts situated behind the axle. Its wings were of unequal span. It was powered by a single [[ABC Dragonfly]] [[radial engine|radial]] engine, which was installed on the nose in a [[wikt:streamlined|streamline]]d [[cowling]]. To regulate the engine's temperature, each individual [[Cylinder (engine)|cylinder]] had its own cooling channel. Armament consisted of a pair of [[Vickers machine gun]]s mounted directly in front of the pilot.<ref name="mason fighter p149"/><ref name="Tapper p118"/>

The Siskin made its first flight in May 1919.<ref name="Tapper p118"/> While the initial aircraft was powered by the intended Dragonfly engine, it would only deliver {{cvt|270|hp}} rather than the expected {{cvt|320|hp}}.<ref name="mason fighter p149">Mason 1992, p. 149.</ref> Despite early promise, the Dragonfly was disastrous, being less powerful, unreliable, and prone to overheating while excessive vibration resulted in [[crankshaft]] failures after only a few hours of use.<ref name="Gunen p8-9">Gunston 1986, pp. 8–9.</ref> Despite the engine, the Siskin displayed generally good properties, possessing favourable stability and handling characteristics, along with performance that could outmatch its direct rivals for RAF orders.<ref name="silver pt5 p74">Lumsden 1991, p. 74.</ref><ref name="Tapper p118"/>

===Redesign===
In 1919, Siddeley-Deasy merged with [[Armstrong Whitworth]], with the aviation interests becoming [[Armstrong Whitworth Aircraft]].<ref name="Tapper p18">Tapper 1988, p. 18.</ref> Siddeley-Deasy had inherited the design of the RAF 8 fourteen-cylinder radial engine and its designer [[Samuel Dalziel Heron|Sam D. Heron]]. By 1920, this engine, as the [[Armstrong Siddeley Jaguar|Jaguar]], had been developed sufficiently to replace the Dragonfly.<ref name="silver pt5 p73-4">Lumsden 1991, pp. 73–74.</ref><ref name="Tapper p118"/> A prototype Siskin fitted with a Jaguar flew on 20 March 1921.<ref name="mason fighter p149"/> Air Ministry officials were impressed but urged Armstrong Whitworth to continue developing the aircraft as only an all-metal design would be acceptable to the [[Royal Air Force]] (RAF).<ref name="Tapper p1189">Tapper 1988, pp. 118-119.</ref>

During 1922, [[List_of_Air_Ministry_specifications#RAF_specifications_(1918–1920)|Air Ministry Specification 14/22]] was issued for an all-metal single-seat high performance landplane. The Siskin was submitted leading to an order for a single Jaguar-powered prototype.<ref name="basf51">Meekcoms and Morgan 1994, p. 51.</ref> Aside from the engine change, Major Green redesigned it with an all-metal structure, as the ''Siskin III''. The all-metal Siskin was the start of the British transition to metal for military aircraft.<ref name=Ritchie>Ritchie, 1997, pp.25-26</ref><ref name="Tapper p11921">Tapper 1988, pp. 119-121.</ref>

===Into production===
[[File:Armstrong_Whitworth_Siskin_III_RAF.jpg|thumb|left|Armstrong Whitworth Siskin III, J7147, construction no. 31, issued to [[No. 41 Squadron RAF|No. 41 Squadron]] on 7 May 1924. It was destroyed in a flying accident on 9 October 1924.]]
On 13 October 1922, an initial contract for three production aircraft was placed, and a follow-on order for a further six followed on 26 January 1923, including a single two-seat variant.<ref name="basf66">Meekcoms and Morgan 1994, p. 66.</ref> The Siskin III made its first flight on 7 May 1923.<ref name="mason fighter p164">Mason 1992, p. 164.</ref><ref name="Tapper p123">Tapper 1988, p. 123.</ref> A comprehensive evaluation was conducted, during which the [[aileron]]s were [[wikt:tapered|tapered]] to prevent them jamming, as happened during one test flight. Shortly thereafter, Armstrong Whitworth commenced construction of the production standard Siskin, the first of which were delivered to the [[Royal Air Force]] (RAF) in January 1924<ref name="mason fighter p164"/> for flight trials on [[No. 41 Squadron RAF|No. 41 Squadron]]. The fighter was constructed with a composite wood and aluminium frame, covered in doped linen fabric.

Following the orders from the RAF, Armstrong Whitworth worked on securing export sales for the Siskin. Siskin sales played a major role in the company's fortunes for a time.<ref name="Tapper p178">Tapper 1988, pp. 17-18.</ref> [[Romania]] ordered 65 aircraft, but cancelled the order following a fatal accident at Whitley Abbey, [[Coventry]] on 18 February 1925 when a Romanian pilot died in a crash on take off, during acceptance tests.<ref name="mason fighter p165">Mason 1992, p. 165.</ref> Political pressure by France may have also contributed to the order's cancellation however.<ref name="Tapper p128">Tapper 1988, p. 128.</ref>

The Siskin IIIA was the main production version, which was first ordered during 1926,<ref name="b">{{cite web|last=Moss |first=Roger |title=Armstrong Whitworth Siskin |url=http://britishaviation-ptp.com/id122.html |work=British Aviation – Projects to Production |access-date=4 May 2011 |url-status=dead|archive-url=https://web.archive.org/web/20110812212702/http://britishaviation-ptp.com/id122.html |archive-date=12 August 2011 }}</ref> and was the first all-metal framed aircraft to be procured in quantity for the RAF.<ref name="Tapper p141">Tapper 1988, p. 141.</ref> This variant was to have been powered with a Jaguar IV, but was given a [[supercharger|supercharged]] Jaguar IVA engine instead. The supercharger had little effect on performance below {{cvt|10000|ft}}, but greatly improved speed and climb above that height.<ref name="mason fighter p165"/> The [[Royal Canadian Air Force]] received 12 IIIAs between 1926 and 1931 after evaluating two Siskin IIIs.{{CN|date=January 2021}}

Early production examples were built by Armstrong Whitworth but<ref name="Tapper p124">Tapper 1988, p. 124.</ref> due to production demands for the [[Armstrong Whitworth Atlas|Atlas]], some Siskin IIIA production was [[subcontract]]ed out to [[Blackburn Aircraft|Blackburn]], [[Bristol Aeroplane Company|Bristol]], [[Gloster Aircraft Company|Gloster]], and [[Vickers]].<ref name="Tapper p1401">Tapper 1988, pp. 140–141.</ref>

==Operational history==
===Royal Air Force===
[[File:Siskins of 29.jpg|thumb|29 Squadron Siskin lineup, late 1920s.]]

During May 1924, the RAF's first Siskin IIIs were delivered to [[No. 41 Squadron RAF|No. 41 Squadron]] at [[RAF Northolt]].<ref name="mason fighter p164"/> Shortly thereafter, [[No. 111 Squadron RAF|No. 111 Squadron]] also received the model; its adoption enabled No. 111 to become the RAF's first high-altitude fighter squadron.<ref name="Tapper p129">Tapper 1988, p. 129.</ref> The Siskin III was relatively popular amongst its pilots, being a highly manoeuvrable aircraft, although slightly underpowered. Between 1925 and 1931, Siskins were frequently presented at RAF exhibitions of flying; one particular feat performed was the linking of three aircraft by cords between their interplane struts, necessitating careful formation flying to not break these cords until the finishing manoeuvre was performed.<ref name="Tapper p132">Tapper 1988, p. 132.</ref>

During September 1926, the first deliveries of the improved Siskin IIIA variant were made to No. 111 Squadron.<ref name="donald">Donald 1997, p. 64.</ref><ref name="Tapper p131">Tapper 1988, p. 131.</ref> In total, the Siskin was operated by eleven RAF squadrons. By 1931, the type was showing its age, leading to the Air Ministry considering either to recondition them or to procure new-built fighters to replace them.<ref name="Tapper p1334">Tapper 1988, pp. 133-134.</ref> During October 1932, the final Siskins in RAF service were withdrawn, the type having been replaced by the newer and more capable [[Bristol Bulldog]].<ref name="donald"/>

===Sweden===
The second Siskin II aircraft was sold to the [[Royal Swedish Air Force]] in 1925.<ref name="Jackson45">Jackson 1973, p. 45.</ref> It was equipped with skis and flown in an experimental capacity for a time.<ref name="Tapper p122">Tapper 1988, p. 122.</ref>

===Canada===
[[File:AW Siskin 2-seater trainer.jpg|thumb|left|RCAF Siskin IIIDC, c. 1937 (PAC Photo).]]
Between 1926 and 1939, Canada operated a sizable fleet of Siskins. During 1926, the British Air Ministry had dispatched a pair of Siskin IIIs to Canada, where they underwent testing by the [[Royal Canadian Air Force]] (RCAF) under winter flying conditions by test pilot [[Punch Dickins|Clennell H. Dickins]].<ref name="Tapper p135">Tapper 1988, p. 135.</ref> The Siskin was considered a modern type at the time of its acquisition by the RCAF, which opted to purchase the Mark IIIA. The Canadian procurement involved both new-built aircraft and second-hand RAF Siskins being supplied to numerous RCAF squadrons.<ref name="Tapper p135"/>

The Siskin equipped the Fighter Flight at [[Camp Borden]] and [[CFB Trenton|Trenton]]. During 1937, the Flight became No. I (Fighter) Squadron, and was transferred from Trenton to [[RCAF Station Calgary|Calgary]] in August 1938.<ref name="Tapper p136"/> RCAF Siskins were also frequently used in aerial displays and long distance tours around North America.<ref name="Tapper p1356">Tapper 1988, pp. 135-136.</ref>

[[File:Armstrong-Whitworth Siskin ExCC.jpg|thumb|RAF Armstrong-Whitworth Siskin IIIa from No. 41 Squadron at Northolt being serviced with oxygen]]
The unit continued to operate the Siskin up until the outbreak of the [[World War II|Second World War]], shortly after which the type was rapidly retired and replaced by [[Hawker Hurricane]] [[monoplane]] fighters.<ref name="Tapper p136">Tapper 1988, pp. 136.</ref> Following the Siskin's  withdrawal by the RCAF, the airframes were turned over to various technical establishments for use as instructional airframes.{{CN|date=January 2021}}

Like its RAF counterparts, in 1929, a three-plane [[Siskins|Siskin air demonstration team]] was formed at Camp Borden, Ontario – the RCAF's first official flight demonstration team.<ref>Millberry 1984, p. 45.</ref> The aerobatic team put on popular solo and formation displays from coast to coast.<ref>Dempsey 2002, pp. 25–41.</ref>

===Air racing===
The Siskin frequently participated in [[air racing]], often triumphing in such events. Multiple examples were entered into the 1924 [[King's Cup air race]], one of which achieving the fastest course time despite arriving fourth.<ref name="Tapper p1246">Tapper 1988, pp. 124-126.</ref> In the 1925 King's Cup, a Siskin V flown by [[Flight Lieutenant]] Barnard emerged as the winner, having reportedly achieved a speed in excess of {{cvt|151|mph}}.<ref name="jackson 1 p57">Jackson 1973, p. 57.</ref>

==Variants==
* '''Siddeley Deasy S.R.2 Siskin''' – Prototype fighter aircraft built by Siddeley-Deasy and powered by Dragonfly engine. Three built.<ref name="Tapper p118">Tapper 1988, p. 118.</ref>
* '''Siskin II''' – fabric covered steel-tube fuselage and wooden wings. Two built, one two-seater and one single-seater.<ref name="Tapper p121-2">Tapper 1988, pp. 121–122.</ref>
* '''Siskin III''' – all-metal production version (64 built for RAF<ref name="Tapper p371">Tapper 1988, p. 371.</ref>)
* '''Siskin IIIA''' – main production variant ordered in 1926<ref name="b"/> (Total 348 built, 340 for RAF, eight for RCAF<ref name="Tapper p371"/>)
* '''Siskin IIIB''' – prototype with improved engine. Single example converted from Siskin IIIA.<ref name="Tapper p369,1">Tapper 1988, pp. 369, 371.</ref>
* '''Siskin IIIDC''' – two-seat dual control version (Total 53 built, 47 for RAF, two for RCAF, two for AST, two for Estonia<ref name="Tapper p371"/>) a further 32 were converted from Siskin IIIs.
* '''Siskin IV''' – civil racing version (one built<ref name="Tapper p371"/>)
* '''Siskin V''' – single-seat fighter for Romania. 65 ordered and at least 10 completed before order cancelled. Two used for racing.<ref name="Tapper p126-8">Tapper 1988, pp. 126–128.</ref>

==Operators==

===Military operators===
;{{flag|Canada|1921}}
*[[Royal Canadian Air Force]]
**Fighter Flight
**[[No. 1 Squadron RCAF|No. 1 Squadron]] (1937–1939)
**[[Siskins]] Aerobatic team (1929–1932)
;{{EST}}
*[[Estonian Air Force]] - operated two Siskin IIIDCs from 1930 to 1940.<ref>Gerdesson 1982, pp. 69, 76</ref>
;{{SWE}}
*[[Royal Swedish Air Force]]
;{{UK}}
*[[Royal Air Force]]<ref name="silver pt6 p143-4">Thetford 1991, pp. 143–144.</ref>
**[[No. 1 Squadron RAF|No. 1 Squadron]]
**[[No. 17 Squadron RAF|No. 17 Squadron]]
**[[No. 19 Squadron RAF|No. 19 Squadron]]
**[[No. 25 Squadron RAF|No. 25 Squadron]]
**[[No. 29 Squadron RAF|No. 29 Squadron]]
**[[No. 32 Squadron RAF|No. 32 Squadron]]
**[[No. 41 Squadron RAF|No. 41 Squadron]]
**[[No. 43 Squadron RAF|No. 43 Squadron]]
**[[No. 54 Squadron RAF|No. 54 Squadron]]
**[[No. 56 Squadron RAF|No. 56 Squadron]]
**[[No. 111 Squadron RAF|No. 111 Squadron]]

===Civil operators===
;{{UK}}
* [[Air Service Training]]<ref name="Jackson47">Jackson 1973, p. 47.</ref>

==Specifications (Siskin IIIA)==
{{Aircraft specs
|ref= ''The British Fighter since 1912''<ref name="mason fighter p166">Mason 1992, p. 166.</ref>
|prime units?= imp
<!--General characteristics-->
|crew= 1
|length ft=25
|length in=4
|span ft=33|
|span in=2
|height ft=10|
|height in=2
|wing area sqft= 293
|airfoil=
|empty weight lb= 2,061
|max takeoff weight lb= 3,012
<!--Powerplant-->
|eng1 number= 1
|eng1 name=[[Armstrong Siddeley Jaguar IV]]
|eng1 type=14-cylinder air-cooled [[radial engine|radial piston engine]]
|eng1 hp=385
|eng1 note=<ref name="Tapper p142">Tapper 1988, p. 142.</ref>
|prop blade number= 2
|prop name= fixed-pitch propeller
|prop dia ft=|
|prop dia in=
<!--Performance-->
|max speed mph= 156
|max speed note= at sea level 
|range miles=280
|range note=<ref name="Angelucci">Angelucci 1981, p. 118.</ref>
|endurance=72 minutes
|ceiling ft=27,000
|climb rate ftmin=2,953
|climb rate note=
|time to altitude={{cvt|10000|ft}} in 7 minutes and 5 seconds
|more performance=
<!--Armament-->
|guns= Two × {{cvt|0.303|in|1}} [[Vickers machine guns]]
|bombs= Four × {{cvt|20|lb}} bombs under-wing
}}

==See also==
{{aircontent|
|related=
|similar aircraft=
* [[Gloster Gamecock]]
* [[Gloster Grebe]]
* [[Hawker Woodcock]]
|lists=
* [[List of aircraft of Canada's air forces]]
* [[List of aircraft of the Royal Air Force]]
|see also=
}}

==References==
{{Commons category}}
===Citations===
{{reflist|30em}}

===Bibliography===
* Angelucci, Enzo. ''World Encyclopedia of Military Aircraft''. London: Jane's Publishing, 1981. {{ISBN|0-7106-0148-4}}
* Dempsey, Daniel V. ''A Tradition of Excellence: Canada's Airshow Team Heritage''. Victoria, BC: High Flight Enterprises, 2002. {{ISBN|0968781705}}
* Donald, David (ed.). ''The Encyclopedia of World Aircraft''. London: Aerospace Publishing, 1997. {{ISBN|185605375-X}}
* Gerdessen, F. "Estonian Air Power 1918 – 1945". ''[[Air Enthusiast]]'', No. 18, April – July 1982. pp. 61–76. {{ISSN|0143-5450}}
* [[Bill Gunston|Gunston, Bill]]. ''World Encyclopaedia of Aero Engines''. Book Club Associates, 1986
* Jackson, A.J. ''British Civil Aircraft since 1919, Volume 1''. London: Putnam, 2nd Edition, 1973. {{ISBN|0370100069}}
* Lumsden, Alec. "On Silver Wings — Part 5". ''[[Aeroplane Monthly]]'', February 1991, Vol 19 No 2, Issue 214. pp.&nbsp;72–78. ISSN 0143-7240
* Mason, Francis K. ''The British Fighter Since 1912''. Annapolis, Maryland: Naval Institute Press, 1992. {{ISBN|1-55750-082-7}}
* Meekcoms, K J and Morgan, E B. ''The British Aircraft Specification File.'' Tonbridge, Kent, UK: [[Air-Britain]], 1994. {{ISBN|0851302203}}
* Milberry, Larry. ''Aviation in Canada''. Toronto: McGraw-Hill Ryerson Limited, 1979. {{ISBN|0070827788}}
* Milberry, Larry. ''60 Years: The RCAF and CF Air Command 1924–1984''. Toronto: Canav Books, 1984. {{ISBN|0969070349}}
* {{cite book|last=Ritchie|first=Sebastian|title=Industry and Air Power The Expansion of British Aircraft Production 1935-1941|publisher=Routledge Taylor and Francis Group|year=1997|isbn=0714643432}}
* Tapper, Oliver. ''Armstrong Whitworth Aircraft since 1913''. London:Putnam, 1988. {{ISBN|0851778267}}.
* Thetford, Owen. "On Silver Wings — Part 6". ''Aeroplane Monthly'', March 1991, Vol 19 No 3, Issue 215, pp.&nbsp;138–144. London: IPC. ISSN  0143-7240.

{{Armstrong Whitworth aircraft}}
{{Aircraft manufactured in Canada}}

[[Category:Racing aircraft]]
[[Category:Single-engined tractor aircraft]]
[[Category:1920s British fighter aircraft]]
[[Category:Armstrong Whitworth aircraft|Siskin]]
[[Category:Sesquiplanes]]
[[Category:Aircraft first flown in 1919]]