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
First World War
.
Development of the Siskin was heavily influenced by
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
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
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 Bulldogs
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
Second World War
. Several Siskins were also entered in various
air races
.
Development
[
edit
]
Background
[
edit
]
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.
[3]
A major impetus for the aircraft's development was the
Air Ministry
's issuing of
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.
[3]
[4]
The SR.2 Siskin was a single-
bay
biplane
of wood and fabric construction. It angular in form, with little attention paid to obvious avenues for
drag
reduction.
[5]
Perhaps its most distinctive feature was its fixed
conventional landing gear
, which had relatively lengthy
oleo strut
shock absorbers
carrying the
axle
, which was in turn connected by
radius rods
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, which was installed on the nose in a
streamlined
cowling
. To regulate the engine's temperature, each individual
cylinder
had its own cooling channel. Armament consisted of a pair of
Vickers machine guns
mounted directly in front of the pilot.
[1]
[6]
The Siskin made its first flight in May 1919.
[6]
While the initial aircraft was powered by the intended Dragonfly engine, it would only deliver 270 hp (200 kW) rather than the expected 320 hp (240 kW).
[1]
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.
[7]
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.
[8]
[6]
Redesign
[
edit
]
In 1919, Siddeley-Deasy merged with
Armstrong Whitworth
, with the aviation interests becoming
Armstrong Whitworth Aircraft
.
[9]
Siddeley-Deasy had inherited the design of the RAF 8 fourteen-cylinder radial engine and its designer
Sam D. Heron
. By 1920, this engine, as the
Jaguar
, had been developed sufficiently to replace the Dragonfly.
[10]
[6]
A prototype Siskin fitted with a Jaguar flew on 20 March 1921.
[1]
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).
[11]
During 1922,
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.
[12]
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.
[13]
[14]
Into production
[
edit
]
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.
[15]
The Siskin III made its first flight on 7 May 1923.
[16]
[5]
A comprehensive evaluation was conducted, during which the
ailerons
were
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
[16]
for flight trials on
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.
[17]
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.
[18]
Political pressure by France may have also contributed to the order's cancellation however.
[19]
The Siskin IIIA was the main production version, which was first ordered during 1926,
[20]
and was the first all-metal framed aircraft to be procured in quantity for the RAF.
[21]
This variant was to have been powered with a Jaguar IV, but was given a
supercharged
Jaguar IVA engine instead. The supercharger had little effect on performance below 10,000 ft (3,000 m), but greatly improved speed and climb above that height.
[18]
The
Royal Canadian Air Force
received 12 IIIAs between 1926 and 1931 after evaluating two Siskin IIIs.
[
citation needed
]
Early production examples were built by Armstrong Whitworth but
[22]
due to production demands for the
Atlas
, some Siskin IIIA production was
subcontracted
out to
Blackburn
,
Bristol
,
Gloster
, and
Vickers
.
[23]
Operational history
[
edit
]
Royal Air Force
[
edit
]
During May 1924, the RAF's first Siskin IIIs were delivered to
No. 41 Squadron
at
RAF Northolt
.
[16]
Shortly thereafter,
No. 111 Squadron
also received the model; its adoption enabled No. 111 to become the RAF's first high-altitude fighter squadron.
[24]
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.
[25]
During September 1926, the first deliveries of the improved Siskin IIIA variant were made to No. 111 Squadron.
[26]
[27]
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.
[28]
During October 1932, the final Siskins in RAF service were withdrawn, the type having been replaced by the newer and more capable
Bristol Bulldog
.
[26]
Sweden
[
edit
]
The second Siskin II aircraft was sold to the
Royal Swedish Air Force
in 1925.
[29]
It was equipped with skis and flown in an experimental capacity for a time.
[30]
Canada
[
edit
]
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
Clennell H. Dickins
.
[31]
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.
[31]
The Siskin equipped the Fighter Flight at
Camp Borden
and
Trenton
. During 1937, the Flight became No. I (Fighter) Squadron, and was transferred from Trenton to
Calgary
in August 1938.
[32]
RCAF Siskins were also frequently used in aerial displays and long distance tours around North America.
[33]
The unit continued to operate the Siskin up until the outbreak of the
Second World War
, shortly after which the type was rapidly retired and replaced by
Hawker Hurricane
monoplane
fighters.
[32]
Following the Siskin's withdrawal by the RCAF, the airframes were turned over to various technical establishments for use as instructional airframes.
[
citation needed
]
Like its RAF counterparts, in 1929, a three-plane
Siskin air demonstration team
was formed at Camp Borden, Ontario ? the RCAF's first official flight demonstration team.
[34]
The aerobatic team put on popular solo and formation displays from coast to coast.
[35]
Air racing
[
edit
]
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.
[36]
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 151 mph (243 km/h).
[37]
Variants
[
edit
]
- Siddeley Deasy S.R.2 Siskin
? Prototype fighter aircraft built by Siddeley-Deasy and powered by Dragonfly engine. Three built.
[6]
- Siskin II
? fabric covered steel-tube fuselage and wooden wings. Two built, one two-seater and one single-seater.
[38]
- Siskin III
? all-metal production version (64 built for RAF
[39]
)
- Siskin IIIA
? main production variant ordered in 1926
[20]
(Total 348 built, 340 for RAF, eight for RCAF
[39]
)
- Siskin IIIB
? prototype with improved engine. Single example converted from Siskin IIIA.
[40]
- Siskin IIIDC
? two-seat dual control version (Total 53 built, 47 for RAF, two for RCAF, two for AST, two for Estonia
[39]
) a further 32 were converted from Siskin IIIs.
- Siskin IV
? civil racing version (one built
[39]
)
- Siskin V
? single-seat fighter for Romania. 65 ordered and at least 10 completed before order cancelled. Two used for racing.
[41]
Operators
[
edit
]
Military operators
[
edit
]
-
Canada
-
Estonia
-
Sweden
-
United Kingdom
Civil operators
[
edit
]
-
United Kingdom
Specifications (Siskin IIIA)
[
edit
]
Data from
The British Fighter since 1912
[45]
General characteristics
- Crew:
1
- Length:
25 ft 4 in (7.72 m)
- Wingspan:
33 ft 2 in (10.11 m)
- Height:
10 ft 2 in (3.10 m)
- Wing area:
293 sq ft (27.2 m
2
)
- Empty weight:
2,061 lb (935 kg)
- Max takeoff weight:
3,012 lb (1,366 kg)
- Powerplant:
1 ×
Armstrong Siddeley Jaguar IV
14-cylinder air-cooled
radial piston engine
, 385 hp (287 kW)
[46]
- Propellers:
2-bladed fixed-pitch propeller
Performance
- Maximum speed:
156 mph (251 km/h, 136 kn) at sea level
- Range:
280 mi (450 km, 240 nmi)
[47]
- Endurance:
72 minutes
- Service ceiling:
27,000 ft (8,200 m)
- Rate of climb:
2,953 ft/min (15.00 m/s)
- Time to altitude:
10,000 ft (3,048 m) in 7 minutes and 5 seconds
Armament
See also
[
edit
]
Aircraft of comparable role, configuration, and era
Related lists
References
[
edit
]
Citations
[
edit
]
- ^
a
b
c
d
Mason 1992, p. 149.
- ^
Tapper 1988, p. 140.
- ^
a
b
Mason 1992, p. 148.
- ^
Tapper 1988, p. 117.
- ^
a
b
Tapper 1988, p. 123.
- ^
a
b
c
d
e
Tapper 1988, p. 118.
- ^
Gunston 1986, pp. 8?9.
- ^
Lumsden 1991, p. 74.
- ^
Tapper 1988, p. 18.
- ^
Lumsden 1991, pp. 73?74.
- ^
Tapper 1988, pp. 118-119.
- ^
Meekcoms and Morgan 1994, p. 51.
- ^
Ritchie, 1997, pp.25-26
- ^
Tapper 1988, pp. 119-121.
- ^
Meekcoms and Morgan 1994, p. 66.
- ^
a
b
c
Mason 1992, p. 164.
- ^
Tapper 1988, pp. 17-18.
- ^
a
b
Mason 1992, p. 165.
- ^
Tapper 1988, p. 128.
- ^
a
b
Moss, Roger.
"Armstrong Whitworth Siskin"
.
British Aviation ? Projects to Production
. Archived from
the original
on 12 August 2011
. Retrieved
4 May
2011
.
- ^
Tapper 1988, p. 141.
- ^
Tapper 1988, p. 124.
- ^
Tapper 1988, pp. 140?141.
- ^
Tapper 1988, p. 129.
- ^
Tapper 1988, p. 132.
- ^
a
b
Donald 1997, p. 64.
- ^
Tapper 1988, p. 131.
- ^
Tapper 1988, pp. 133-134.
- ^
Jackson 1973, p. 45.
- ^
Tapper 1988, p. 122.
- ^
a
b
Tapper 1988, p. 135.
- ^
a
b
Tapper 1988, pp. 136.
- ^
Tapper 1988, pp. 135-136.
- ^
Millberry 1984, p. 45.
- ^
Dempsey 2002, pp. 25?41.
- ^
Tapper 1988, pp. 124-126.
- ^
Jackson 1973, p. 57.
- ^
Tapper 1988, pp. 121?122.
- ^
a
b
c
d
Tapper 1988, p. 371.
- ^
Tapper 1988, pp. 369, 371.
- ^
Tapper 1988, pp. 126?128.
- ^
Gerdesson 1982, pp. 69, 76
- ^
Thetford 1991, pp. 143?144.
- ^
Jackson 1973, p. 47.
- ^
Mason 1992, p. 166.
- ^
Tapper 1988, p. 142.
- ^
Angelucci 1981, p. 118.
Bibliography
[
edit
]
- 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
- 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. 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
- Ritchie, Sebastian (1997).
Industry and Air Power The Expansion of British Aircraft Production 1935-1941
. Routledge Taylor and Francis Group.
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. 138?144. London: IPC. ISSN 0143-7240.
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