Sopwith 1½ Strutter

Infobox Aircraft


name=Sopwith 1½ Strutter
type=Biplane general purpose aircraft
manufacturer=Sopwith Aviation Company
number built=4,500 France
1,439 Great Britain
first flight = December 1915
introduction = April 1916
primary user = Royal Naval Air Service
more users = Royal Flying Corps
"Aéronautique Militaire"

The Sopwith 1½ Strutter was a British one or two-seat biplane multi-role aircraft of the First World War. Lake 2002, p. 40.] It is significant as the first British designed two seater tractor fighter, and the first British aircraft to enter service with a synchronised machine gun. It also saw widespread but rather undistinguished service with the French "Aéronautique Militaire".

Design and development

Designed by the Sopwith Aviation Company, originally for service with the Royal Naval Air Service, the 1½ Strutter was so nicknamed because each of the upper wings (there was no true centre section) were connected to the fuselage by a pair of short (half) struts and a pair of longer struts, forming a "W" when viewed from the front. The aircraft had airbrakes on the lower wings and was powered by a 130-hp (97 kW) Clerget rotary engine.

The main armament was one fixed .303-in Vickers machine gun and up to four 56 lb (25 kg) bombs. In the two seat version, the observer was armed with a Lewis gun on a Scarff ring mount. In December 1915, the Vickers-Challenger interrupter gear was put into production for the Royal Flying Corps and in a few weeks a similar order for the Scarff-Dibovski gear was placed for the RNAS. These gears were fitted to early 1½ Strutters until it was possible to standardise on the improved Ross gear. Early mechanical synchronisation gears were notoriously unreliable and it was not uncommon for propellers to be damaged, or even entirely shot away.

Some early production aircraft were initially built without the forward firing gun because Vickers guns, as well as the necessary synchronisation gears, were in short supply. The Scarff ring mounting was also very new, and production was at first slower than that of the aircraft requiring them. Various makeshift Lewis mountings, as well as the older Nieuport ring mounting, were fitted to some early 1½ Strutters as an interim measure.

From the beginning, a dedicated light bomber version was planned, with the observer's cockpit eliminated to allow for more fuel and bombs to be carried, in the manner of the Martinsyde Elephant and the B.E.12.

Operational history

The prototype two-seater flew in December 1915 Bruce 28 September 1956, p.544.] and production deliveries started to reach the RNAS in February 1916. By the end of April, No. 5 Wing RNAS had a complete flight of the new aircraft, using them both to escort the Wing's Caudron G.4 and Breguet bombers and to carry out bombing raids themselves. Bruce 28 September 1956, p.545.] Thetford 1978, p.292] The War Office had ordered the type for the RFC at the same time, but because Sopwiths were contracted to the Navy for their entire production, the RFC orders had to be placed with Ruston Proctor and Vickers, and production from these manufacturers did not get into its stride until August. Since the Somme offensive was planned for the end of June, and the type was far more urgently required by the RFC than by the RNAS the situation was clearly farcical, and in the event some aircraft had to be transferred from one service to the other - allowing No. 70 squadron to reach the front by early July 1916, with Sopwith-built Strutters originally intended for the navy.

At first No. 70 did very well with their new mounts. The period of German ascendency known as the Fokker scourge was long over, and the 1½ Strutter's long range, coupled with its excellent armament for the period, enabled effective offensive patrolling deep into German held territory. Unfortunately, by the time No. 45 Squadron reached the front in October the new Albatros fighters were appearing in the Jagdstaffeln. By January 1917, when No 43 Squadron arrived in France, the type was totally outclassed as a fighter; although it was still a useful long-range reconnaissance aircraft. Like most early Sopwith types, the 1½ Strutter was very lightly built, and its structure did not stand up very well to arduous war service. It was also far too stable to make a good dogfighter. The last front line 1½ Strutters in the RFC were replaced by Camels in late October 1917. Bruce 5 October 1956, p.588.]

This was by no means the end of the story as far the Sopwith two seater's service was concerned. The type's long range and stability were both good qualities for a home defence fighter, and it served with three home defence squadrons, No. 37, No. 44 and No. 78 Squadrons. Most of the 1½ Strutters supplied to home defence units had been built as two seaters, but many were converted "in the field" to single seaters in order to improve performance. Some of these single seaters were similar to the bomber variant, but others were of different type, known (like similarly adapted Sopwith Camels) as the Sopwith Comic. The cockpit was moved back, behind the wings, and one or two Lewis guns, either mounted on Foster mountings, or fixed to fire upwards, outside the arc of the propeller, replaced the synchronised Vickers.

The RNAS used most of their 1½ Strutters as bombers (in the Aegean and Macedonia as well as in France) and as shipboard aircraft. In this service it was known as the Ship's Strutter and flew from aircraft carriers and other warships of the Royal Navy.

Both the RNAS and the RFC (and, after April 1918, the RAF) used the type as a trainer after its operational days were over. Like the Pup, it proved a popular personal aircraft for senior officers.

The largest user of the Sopwith, however, was the French "Aéronautique Militaire". By October 1916 it was obvious that the pusher Farman and Breguet bombers of the time had become totally obsolete, and pending the appearance of French tractor aircraft the Sopwith was ordered in very large numbers from French manufacturers - in three versions, the SOP. 1A2 (two seater reconnaissance), SOP. 1B2 (two seater bomber) and SOP. 1B1 (single seater bomber). For want of a better alternative the French Sopwiths had to soldier on long after they had become obsolete, and were not fully replaced by later types until early 1918. Three Belgian and three American squadrons also flew French-built Sopwiths, and some seem to have been supplied to Russia. Surplus French Sopwiths were used by several countries post-war.

1½ Strutters were also used by the Soviets and White Russians during the Russian civil war and Polish-Soviet war. Three were captured during this war and used by the Poles in 1919-1920.Kopański, Tomasz Jan: Samoloty brytyjskie w lotnictwie polskim 1918-1930 (British aircraft in the Polish air force 1918-1930), Bellona, Warsaw 2001, ISBN 83-11-09315-6, p.73-78 (in Polish)] Other captured ones were used by Baltic states.

Around 1,500 1½ Strutters were built for the Royal Flying Corps and the Royal Naval Air Service, and between 4,200 and 4,500 were built in France.

Variants

;Sopwith Type 9400 : An original Admiralty designation.;Sopwith Type 9700 : Another Admiralty designation.;Sopwith Two-seater : The original RFC designation.;Sopwith 1½ Strutter : Single or two-seat fighter-scout, bomber and reconnaissance biplane.;Sopwith Comic : Single seat home defence fighter;Ship Strutter : Shipboard version;SOP. 1: French built version.

Operators

;flagcountry|Afghanistan|1919
*Afghanistan Air Force acquired a few aircraft from 1921 and retired in 1925.;AUS
*Australian Flying Corps
**No. 2 Squadron AFC operated one aircraft for training only.
**No. 4 Squadron AFC used Strutters for training.
**No. 6 (Training) Squadron AFC in the United Kingdom;BEL
*Belgian Air Force.;EST
*Estonian Air Force operated a single ex-Soviet aircraft. [Gerdessen 1982, p.64, 76] ;FRA
*"Aéronautique Militaire";JPN
*Imperial Japanese Army Air Service;LAT
*Latvian Air Force operated at least 1 aircraft captured on the Soviets in 1920;flag|Lithuania|1918
*Lithuanian Air Force;NLD
*Netherlands Air Force;POL
*Polish Air Force operated 3 aircraft captured on the Soviets in 1919-1920;flag|Romania
*Royal Romanian Air Force;RUS
*Imperial Russian Air Force and White Russian forces;USSR
*Soviet Air Force;UK
*Royal Flying Corps
**No. 37 Squadron RFC
**No. 43 Squadron RFC
**No. 44 Squadron RFC
**No. 45 Squadron RFC
**No. 70 Squadron RFC
**No. 78 Squadron RFC
*Royal Naval Air Service;flagcountry|United States|1912
*Aviation Section, U.S. Signal Corps purchased 384 two-seat observation aircraft and 130 single seat bombers from France in 1917-18. Swanborough and Bowers 1963 p.560] While mainly used for training, they were used operationally by the 90th Aero Squadron. Bruce 5 October 1956, p.590.]
*United States Navy Swanborough and Bowers 1976, p.495]

pecifications (1½ Strutter)

aircraft specifications
plane or copter?=plane
jet or prop?=prop
ref=
crew=two, pilot and observer
capacity=
payload main=
payload alt=
length main= 25 ft 3 in
length alt= 7.7 m
span main= 33 ft 6 in
span alt= 10.21 m
height main= 10 ft 3 in
height alt= 3.12 m
area main= 346 ft²
area alt= 32.14 m²
airfoil=
empty weight main= 1,260 lb
empty weight alt= 570 kg
loaded weight main= 2,149 lb
loaded weight alt= 975 kg
useful load main=
useful load alt=
max takeoff weight main= 2,149 lb
max takeoff weight alt= 975 kg
more general=
engine (prop)= Clerget 9B
type of prop=rotary engine
number of props=1
power main= 130 hp
power alt= 97 kW
power original=
max speed main=102 mph
max speed alt= 164 km/h
cruise speed main=
cruise speed alt=
stall speed main=
stall speed alt=
never exceed speed main=
never exceed speed alt=
range main= 350 miles
range alt=565 km
ceiling main= 13,000 ft
ceiling alt= 3,960 m
climb rate main=
climb rate alt=
loading main= 6.21 lb/ft²
loading alt=30.34 kg/m²
thrust/weight=
power/mass main=
power/mass alt=
more performance=
armament=
* 1 × .303 in (7.7 mm) forward-firing Vickers machine gun with Ross interrupter gear
* 1 × .303 in (7.7 mm) Lewis gun in observer's cockpit
* Up to 224 lb (100 kg) bombs
avionics=

ee also

aircontent
related=
*Sopwith Pup
similar aircraft=
*Bristol F.2 Fighter
sequence=
lists=
*List of aircraft of the Royal Flying Corps
*List of aircraft of the Royal Naval Air Service
see also=

References

Notes

Bibliography

* Bruce, J.M. " [http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201390.html The Sopwith 1½ Strutter: Historic Military Aircraft No. 14 Part I] ". "Flight", 28 September 1956, Pages 542-546.
* Bruce, J.M. " [http://www.flightglobal.com/pdfarchive/view/1956/1956%20-%201434.html The Sopwith 1½ Strutter: Historic Military Aircraft No. 14 Part II] ". "Flight", 5 October 1956, Pages 586-591.
* Gerdessen, F. "Estonian Air Power 1918 - 1945". "Air Enthusiast" No 18, April - July 1982. Pages 61-76. ISSN 0143-5450.
* Lake, Jon. "The Great Book of Bombers: The World's Most Important Bombers from World War I to the Present Day". St. Paul, MN: MBI Publishing Company, 2002. ISBN 0-7603-1347-4.
* Swanborough, F.G. and Bowers, Peter. "United States Military Aircraft since 1909". London:Putnam, 1963.
* Swanborough Gordon and Bowers, Peter. "United States Navy Aircraft since 1911".London:Putnam, Second edition 1976. ISBN 0 370 10054 9.
* Taylor, John W.R. "Sopwith 1½ Strutter". "Combat Aircraft of the World from 1909 to the Present". New York: G.P. Putnam's Sons, 1969. ISBN 0-425-03633-2.
* Thetford, Owen. "British Naval Aircraft since 1912". London:Putnam, Fourth edition 1978. ISBN 0 370 30021 1.