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Sopwith 1½ Strutter

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Sopwith 1½ Strutter
Type Biplane general purpose aircraft
Manufacturer Sopwith Aviation Company
Maiden flight December 1915
Primary users RNAS & RFC
Aéronautique Militaire
Number built 4,500 France
1,439 Great Britain

The Sopwith 1½ Strutter was a British one or two-seat biplane multi-role aircraft of the First World War.[1] 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 RNAS, 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 .[1] The aircraft had airbrakes on the lower wings and was powered by a 130-hp (97 kW) Clerget rotary engine.

The main armament was a .303-in Vickers machine gun - and up to four 56 lb (25 kg) bombs could be carried. 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 RFC 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 by no means uncommon for propellers to be damaged, or even entirely shot away.

Some early production aircraft were initially built without pilot's guns – at the time 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 - so that 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 and production deliveries started to reach the RNAS in February 1916. By the end of April, No. 5 wing already had a complete flight of the new aircraft. 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 well 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.

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.

Strangely however, the largest user of the Sopwith two seater 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 so 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.

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.


  • Sopwith Type 9700 : The original 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.


Specifications (1½ Strutter)

General characteristics

  • Crew: two, pilot and observer
  • Length: 25 ft 3 in (7.7 m)
  • Wingspan: 33 ft 6 in (10.21 m)
  • Height: 10 ft 3 in (3.12 m)
  • Wing area: 346 ft² (32.14 m²)
  • Empty weight: 1,260 lb (570 kg)
  • Loaded weight: 2,149 lb (975 kg)
  • Max takeoff weight: 2,149 lb (975 kg)
  • Powerplant:Clerget 9B rotary engine, 130 hp (97 kW)





  1. 1.0 1.1 Lake 2002, p. 40.


  • 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.
  • 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.

See also

Related development
Sopwith Pup Comparable aircraft
Bristol F.2 Fighter

Template:Sopwith Aviation Company aircraft

cs:Sopwith 1 1/2 Strutter de:Sopwith 1 1/2 Strutter fr:Sopwith 1½ Strutter no:Sopwith 1½ Strutter pl:Sopwith 1½ Strutter

This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article "Sopwith 1½ Strutter".