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Sopwith 1-1/2 Strutter (One-and-One-Half Strutter)

Fighter / Reconnaissance / Light Bomber

The Sopwith Strutter was the first British aircraft to feature synchronized firing machine guns.
Authored By: Dan Alex | Edited: 3/12/2019
National Flag Graphic


Year: 1916
Status: Retired, Out-of-Service
Manufacturer(s): Sopwith Aviation Company - UK
Production: 5,939
Capabilities: Fighter; Ground Attack; Reconnaissance (RECCE);
Crew: 1 or 2
Length: 25.23 ft (7.69 m)
Width: 33.50 ft (10.21 m)
Height: 10.24 ft (3.12 m)
Weight (Empty): 1,257 lb (570 kg)
Weight (MTOW): 2,150 lb (975 kg)
Power: 1 x Clerget 9B rotary engine developing 130 horsepower.
Speed: 102 mph (164 kph; 89 kts)
Ceiling: 12,992 feet (3,960 m; 2.46 miles)
Range: 351 miles (565 km; 305 nm)
Operators: Afghanistan; Argentina; Australia; Belgium; Brazil; Estonia; France; Japan; Latvia; Lithuania; Mexico; Netherlands; Poland; Romania; Imperial Russia; Soviet Union; Sweden; Switzerland; Ukraine; United Kingdom; United States
Like other Sopwith Aviation Company aircraft, the wartime Sopwith 1-1/2 Strutter owed its existence to the arrival of the Sopwith Tabloid, a boxy, competition aircraft that sat two in a side-by-side arrangement constructed while being constructed of canvas and wood. The Tabloid design proved a success, earning speed and performance accolades that pushed it to the attention of the British military Despite its limited value as a military mount, the Tabloid nonetheless paved the way for more capable Sopwith designs to come. The 1-1/2 Strutter held two British aviation "firsts" when it was adopted for service - becoming its first "puller" engine arrangement (the engine mounted at the front of the fuselage) two-seater and its first to implement an effective machine gun synchronizer.

Britain went to war in the summer of 1914 and all manner of aircraft were sought for the initiative. This included the Sopwith Tabloid and its floatplane derivatives, the Sopwith Baby and Sopwith Schneider. While these aircraft proved adequate for their given roles of scout (sometimes being armed for the role, sometimes not), they were hardly military-grade end -products built for the rigors of war time abuses. As such, Sopwith engineers took to designing a whole new biplane fighter in the same mold though with changes to incorporate the latest in construction methods while attempting to fulfill the military requirements of a rapidly evolving war in Europe.

Company founder, Thomas Sopwith, along with engineers R.J. Ashfield and Herbert Smith ironed out a new aircraft fuselage with a biplane wing arrangement and inline seating for two - a pilot and an observer/gunner. The powerplant of choice was the French Clerget 9Z rotary engine of 110 horsepower. A single .303 machine gun was fitted in a fixed, forward-firing emplacement, synchronized to fire through the two-bladed spinning propeller blade via a Vickers-Challenger interruptor. For the rear observer, a .303 Lewis machine gun was mounted along a Scarff No. 2 Ring Mounting for trainable fire along the airframe's crucial "six". The wings were supported by struts in a conventional way through full-length, staggered parallel struts making single bays - though half-length struts were used to connect the upper wing assembly to the fuselage (known as cabane struts) and, thusly, this garnered the aircraft the nickname, and ultimately its formal designation, of "1-1/2 Strutter" (One-and-One Half Strutter"). An adjustable rudder surface was added to the vertical tail fin and the wings proved notable in their implementation of pivoting surfaces which were essentially equivalent to later dive brakes. Testing of the 1-1/2 Strutter was undertaken in December of 1915.

The Royal Naval Air Service (RNAS) found interest in this newer dedicated Sopwith military development and procured the type in number with deliveries beginning in February of 1916. Requiring a steady stable of airplanes all its own, the Royal Flying Corps (RFC) joined in procurement of the type, eventually fielding it across nine complete squadrons - No. 37, No. 39, No. 43 (bomber), No. 44, No. 45 (bomber), No. 46, No. 70 (bomber), No. 78 and No. 143. RNAS No. 5 Wing, operating in France, became the first 1-1/2 Strutter squadron in April of 1916. The 1-1/2 Strutter was eventually in such great demand that other British concerns were charged with its production and license manufacture was also handled overseas in factories across France and Imperial Russia. The aircraft would prove to be a commercial success for Sopwith in that operators ultimately spanned the globe in wartime and post-war use - Afghanistan, Australia, Belgium, Brazil, Estonia, France, Greece, Japan, Latvia, Lithuania, Mexico, Netherlands, Poland, Romania, Russia (then later as the Soviet Union), Ukraine, the United Kingdom and the United States. For the United States, the 1-1/2 Strutter stocked the inventories of its US Signal Corps, the United States Navy and the American Expeditionary Force (the latter in action across Europe during World War 1). Civilian use extended to Argentina, France, Japan, Sweden, Switzerland and the United Kingdom.

In practice, the 1-1/2 Strutter compared favorably to the offerings of the Imperial German and Austro-Hungarian air services of the time. The type was utilized initially as a bomber escort and became an effective scout platform all its own. When armed with conventional drop ordnance, the 1-1/2 Strutter proved equally effective as a light two-man bomber. The fuselage eventually came in two flavors for its required roles - produced in twin-seat and single-seat fuselage forms. In 1916, the original Vickers-Challenger interrupter gear was replaced by the more effective Scarff-Dobovsky system. When utilizing a two-man crew, the aircraft was a capable "fighting scout" and benefitted from the "two heads are better than one" mentality. In its single-seat form, construction was simplified and the aircraft lightened to an extent, though more responsibility fell to the single operator now. Within time, a dedicated night-fighter form emerged to combat German incursions over British soil after dark and made up a critical portion of homeland defense squadrons.

Production of 1-1/2 Strutters included 1,439 built for British forces and an additional 4,200 to 4,500 examples built in France brining the combined reported total to nearly 6,000 units.

While quickly brought about to fight in a frontline role, the 1-1/2 Strutter suffered the fate of many-a-World War 1 aircraft - the evolution of technology in the period often led to once-proud mounts being quickly outmoded by arriving enemy designs. 1-1/2 Strutters were superseded by Sopwith Pups and Triplanes beginning to come online throughout 1916 and Strutters were therefore pressed into second-line roles thereafter. All of these designs eventually laid the groundwork for the war-winning Sopwith Camel of mid-1917. 1-1/2 Strutters proved a modest ace-maker as well, Englishman Geoffrey Cock leading the way with 13 confirmed kills.


1 x 7.7mm Vickers Machine Gun in fixed, forward-firing mounting.
1 x 7.7mm Lewis Machine Gun on trainable mounting in rear cockpit position.

Up to 224lb of external ordnance (drop bombs).

Graphical image of an aircraft conventional drop bomb munition

Variants / Models

• Sopwith Type 9400 - Initial Admiralty Designation.
• Sopwith Type 9700 - Initial Admiralty Designation.
• Sopwith Type Two-Seater - Initial RFC Designation.
• Sopwith 1-1/2 Strutter - Fighter-Scout/Bomber/Reconnaissance Variant; produced in single and twin-seat versions.
• Sopwith Comic - Home Defense Variant
• Ship Strutter - Naval Version
• SOP. 1 - French Production Designation
• SOP. 1A2 - French Two-Seat Reconnaissance Variant.
• SOP. 1B2 - French Two-Seat Bomber Variant.
• SOP. 1B1 - French Single Seat Bomber Variant.
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