The Sopwith Menagerie, 1915 – 1916
This blog will examine four of Sopwith’s major First World War designs. With the publication of a second blog, the reader will be able to trace the continuous and gradual development of these famous aircraft, from the 1½ Strutter of 1915 to the Dragon of 1918. Photographs of each aircraft will illustrate the Sopwith “line of descent”.
Thomas Sopwith, already an accomplished pilot, began to produce his own aircraft at Brooklands in 1912. The Sopwith Aviation Company was established in a converted ice-rink in Kingston-on-Thames from early 1913 and, in the eighteen months or so before war was declared, the firm supplied a number of aircraft to the RNAS and RFC, as well as winning the 1914 Schneider Trophy at Monaco. At war’s outbreak, therefore, the company was well known, particularly to the Admiralty, and had won a reputation for building fast and well-designed aircraft.
The company, for much of the First World War, revolved around four men: founder Thomas Sopwith, designer Herbert Smith, works manager Fred Sigrist and test pilot Harry Hawker.
Sopwith 1½ Strutter
As related above, Sopwith had a special relationship with the Admiralty from the beginning and it is no surprise that the latter expressed an interest in the company’s new aircraft when it emerged in 1915. Although Sopwith described the aircraft as the LCT, (possibly the Land Clerget Tractor), the unusual centre-section strut design meant it quickly became known as the 1½ Strutter. Features of the prototype included a variable-incidence tailplane and air-brakes mounted at the lower wing roots, although the latter were not incorporated into production aircraft. Jack Bruce noted that the prototype was not equipped with a forward-firing machine gun, as “the superior performance to be expected from a tractor configuration outweighed the sacrifice of the unobstructed field of fire forward provided by a pusher”, which, he added, “was bold thinking with only 110hp available.” Instead, the observer was able to swivel a Lewis gun, using the French Etévé mounting, in any direction, including over the upper wing.
Nevertheless, a batch of 50 aircraft, followed by another for 100, was ordered by the Admiralty. The compact design and relatively high speed of the aircraft led to its designation as a fighter, although many airframes from the second batch were completed as single-seat bombers. In early 1916, it was decided that a forward-firing gun was desirable and all Strutters, with the exception of the very first aircraft, were so equipped. The problematic Lewis gun arrangement was also dropped in favour of a Scarff-ring-mounted weapon.
The 3rd and 5th Wings of the Royal Naval Air Service (RNAS) began using both versions of the Strutter as a bomber in spring 1916. While the single-seat version was to be used exclusively as a bomber, the two-seater was, somewhat optimistically, employed on patrol duties as well. However, the Admiralty’s planned bombing campaign did not materialise as originally hoped. The crisis on the Western Front, caused by the Battle of Verdun, and the subsequent moving forward of the British Somme offensive, forced the RFC to request the transfer of considerable numbers of aircraft from naval contracts, among which were over 70 Strutters. Naval Strutters continued the Western Front bombing campaign into 1917, while limited numbers were employed as anti-submarine aircraft in the Mediterranean and as bombers in Macedonia. Others were embarked on HMS Furious and HMS Vindex, fitted with wheeled undercarriages or with skids. A number were used to test hydrovanes and flotation gear at the Isle of Grain.
The Royal Flying Corps (RFC) was not far behind the Navy in ordering the new type and, with the Sopwith works running at full capacity, an initial order for fifty aircraft was given to Ruston, Proctor in March 1916. Further batches were built by a multitude of different companies and almost 700 were eventually delivered to the RFC.
Unfortunately, RFC units on the Western Front found the new aircraft to be inferior to the opposition. An improvement in performance was sought by the installation of the 130hp Clerget engine but “this was too late…it was mid-April 1917 before production 1½ Strutters could be so equipped in reasonable numbers, and…the Sopwith was by then hopelessly outclassed.” By October 1917, the Strutter had been withdrawn from the Western Front. Fifty-nine aircraft were converted to “Comic” specification for night-fighting operations and others continued as trainers in the UK.
While a total of approximately 1,300 Strutters was produced in the UK, over 4,500 were built in France, which made great use of the type as a bomber and reconnaissance aircraft. In addition, Belgium, Russia and the United States purchased the Strutter, making it one of the most widely-used aircraft of the First World War.
A Sopwith 1½ Strutter replica can be seen at the RAF Museum, Cosford.
Sopwith SL T B P
This aircraft, allegedly built straight from drawings chalked onto the floor of the Sopwith works by Harry Hawker, can claim to be the forerunner of the Pup. The tailplane and undercarriage followed Sopwith orthodoxy and similar versions were to be found on the Pup, as were the single-bay wings and wing-tips with significant backwards rake.
Harry Hawker used the aircraft as a personal runabout to fly between the various factories building Sopwith aircraft. It is known to have survived until at least 1926, by which time it was converted to a two-seater.
SL T B P may have stood for Sopwith Land Tractor BiPlane.
The late Jack Bruce wrote that “it has been said that the little Sopwith Scout which was to be known as the Pup was designed as a counter-weapon to the Fokker monoplane.” Whatever the truth of this, the Fokker began to make its presence felt in the late autumn of 1915 and the prototype of the Sopwith Pup first flew in February 1916. Possibly it was the exigencies of time, stemming from the Fokker menace, which caused Sopwith to use many of the design attributes of the SL T B P in the new aircraft.
The aircraft was, in comparison to its contemporaries, easy to fly and blessed with a high degree of manoeuvrability, made possible by the concentration of mass in the forward part of the fuselage. A low wing-loading, thanks to a generous chord, bestowed the Pup with an especially fine performance at higher altitudes, enabling it to retain full manoeuvrability to around 15,000 feet and Major James McCudden wrote that “when it came to manoeuvring, the Sopwith Scout would turn twice to an Albatros’ once.”
As Admiralty contractors, it is unsurprising that the first six aircraft were delivered to the RNAS and eventually some 175 Pups were built to naval contracts. Production aircraft first saw action with the RNAS in September 1916.
The RFC was not slow in following the Admiralty’s lead and large contracts were placed with both the Standard and Whitehead companies. The first RFC unit to be fully equipped with the Pup was 54 Squadron, which arrived in France on 24 December 1916. Shortly after production commenced, stronger cabane struts were introduced and although doubt was cast upon the structural strength of the little Sopwith by the Central Flying School, it was found to be satisfactory by the standards of the day. Nevertheless, units discovered that the mainplane panels of the Pup, irrespective of manufacturer or service, had to be replaced after about 40 hours of flying.
In late 1916, in response to a call from the RFC for reinforcements following the Battle of the Somme, the Admiralty dispatched 8 Squadron, RNAS to work with the army. Other RNAS Pup units active on the Western Front included 3, 4 and 9 Squadrons.
The Pup had only two major drawbacks. One was the 80hp Le Rhone or 100hp Le Rhone engine, which limited top speed and climb. The other was the single Vickers gun. In comparison, the Albatros D-series was fitted with a 160hp Mercedes engine and two machine guns. Consequently, as 1917 progressed, the Pup found itself increasingly hard-pressed by the Albatros D.III and D.V. The first Camels were delivered to the RNAS and RFC in June 1917 and thereafter the Pup was gradually withdrawn from service on the Western Front. The last Pup was relinquished by 54 Squadron in December 1917, by which time the type was thoroughly outclassed.
Attempts were made to increase the Pup’s performance. The 100hp Gnome Monosoupape was tried but did not confer any advantage. The 110hp Le Rhone was also tested and, although a slight improvement was gained, it was found that the extra weight of the engine made a three-point landing impossible. Trials confirmed that the static loading of this version was somewhat lower than the standard Pup and in November 1917, work on the aircraft was abandoned. However, as Bruce noted, “it is interesting that this work was still in progress at a time when the Camel and S.E.5a were in operational use [!]”
Some Pups were embarked upon battleships and cruisers during the latter stages of the war as an anti-airship deterrent, while others played a pioneering role in taking off and landing from early aircraft carriers.
A large number of Pups were used by flying schools for training pupils in aerial fighting and several are known to have been retained by instructors for their own use at the Central Flying School and the School of Special Flying, in which role the little fighters acquired a variety of eye-catching colour schemes.
A Sopwith Pup, rebuilt from original parts, can be seen at RAF Museum, Cosford.
This aircraft is chiefly remembered for the great impression it made in the spring of 1917. Excellent manoeuvrability and rate of climb made it more than a match for the Albatros D.III; the German reaction was to call for rival designs, the result of which was the famous Fokker Dr.I.
The Triplane was an almost exact contemporary of the Pup; the fuselage was similar in construction and the armament remained identical. The short chord of the wings endowed the aircraft with excellent manoeuvrability and the pilot with good all-round vision, while the short wingspan gave the Triplane a high rate of roll. From February 1917, the Triplane was fitted with a tailplane of eight feet span, replacing the earlier ten feet span version derived from that of the Pup. At the same time, the engine was upgraded from the 110hp Clerget to the 130hp version which, in spite of the Triplane’s greater drag, gave it a speed advantage over the Pup.
The Triplane only saw action on the Western Front with the RNAS. Although the Triplane was ordered by the War Office, only one example is known to have served with the RFC. There is some confusion in the records over which batch of Triplanes was in fact ordered for the RFC. A request for the transfer of naval aircraft to the army in the autumn of 1916 was eventually fulfilled, the terms of which were that the RFC would hand over its contract for Sopwith Triplanes to the RNAS, while the latter gave up its SPAD VIIs to the former, although “it is doubtful whether any handover to the RNAS of a triplane built for the RFC ever took place, even on paper.” However, in spite of this, the SPADs destined for the RNAS were handed over to the RFC! The firm of Oakley did eventually complete three aircraft, interestingly armed with two Vickers guns each, as were a batch of six Triplanes completed by Clayton & Shuttleworth.
The Triplane equipped a number of naval units, the most distinguished of which was 10 Squadron, RNAS. Led by Raymond Collishaw, the famous all-Canadian B Flight, or “Black Flight” of “Naval 10”, achieved remarkable success during May and June 1917. The aircraft of the Flight featured black engine cowlings and undercarriage wheels and were named Black Maria, Black Sheep, Black George, Black Prince and Black Death. Some of these names were given to more than one airframe, while Black Sheep was renamed Black Maria and Collishaw is known to have flown several Triplanes named Black Maria. The latter wrote:
The Triplane I found to be a delightful machine – in my estimation much preferable to the Pup.
Apart from its manoeuvrability and its rate of climb…the Triplane’s main virtue was the extreme altitude it could attain, and its performance at these heights…
As in the case of all other aircraft, the Triplane had its weaknesses. It was not quite as fast as it might have been, and it could not match a machine such as the Albatros D.III in a dive. Its main failing, though, by comparison with the enemy fighters that it faced, was its armament…It may not have been feasible to have equipped the early Triplanes, which had the 110hp Clerget, with twin Vickers, but I can think of no reason why the 130hp models, which “Naval 10” flew, could not have had two guns.
Six experimental models were in fact fitted with twin Vickers, and I was fortunate enough to obtain one of these before leaving “Naval 10”. When I brought it back to Droglandt it was greeted with mixed feelings. Some of the pilots considered that the extra firepower would be more than offset a reduction in its performance at height…Others, myself included, felt that a certain loss of performance would be acceptable in exchange for the extra gun. I found, in fact, that although there was a definite loss in performance above 10,000 feet, it was relatively slight, and…the firepower…made a big difference.
I continued to fly this machine – N533 – for the remainder of the time I was with “Naval 10”, and wished very much that we had all been given twin-gun types long before. 
The official historian, H.A. Jones, wrote that “the sight of a Sopwith Triplane formation, in particular, induced the enemy pilots to dive out of range.” Although not easily verified, this statement illustrates the high regard in which the Triplane was held by both sides during the spring and summer of 1917.
Unfortunately, the superiority of the Triplane proved to be short-lived, for the new generation of German fighters, notably the Albatros D.V, proved to have the edge in combat. Triplanes began to be phased from front-line service in July and August 1917, although 1 Squadron, RNAS, did not relinquish its last example until December.
Triplane production came to 147 aircraft and some remained on charge in training units in the UK until the end of the war. Ten examples are known to have gone to the French Government and one, still in existence, was operated in Russia.
An Oakley-built Triplane can be seen at the RAF Museum, Hendon.
An attempt to improve performance was made by producing an almost entirely new, and larger, aircraft. Two prototypes were completed, one (serial N509) powered by a 150hp direct-drive Hispano-Suiza engine, the second (serial N510) by a geared 200hp version. The latter aircraft crashed fatally on 20 October 1916. The first prototype was based at Manston for some time, where it flew a number of Home Defence sorties. No development of either version was undertaken.
 J.M. Bruce, The Aeroplanes of the Royal Flying Corps, Putnam, 1982, p. 499.
 Bruce, The Aeroplanes of the Royal Flying Corps, p. 504.
 J.M. Bruce, British Aeroplanes 1914-1918, Putnam, London, 1957, p. 552.
 Bruce, The Aeroplanes of the Royal Flying Corps, p. 517.
 Bruce, The Aeroplanes of the Royal Flying Corps, p. 521.
 Norman Franks, Sopwith Triplane Aces of World War 1, Osprey, Oxford, 2004, pp. 69-70.