The Sopwith Pup was a British single-seater biplane fighter aircraft built by the Sopwith Aviation Company.
It entered service with the Royal Flying Corps and the Royal Naval Air Service in the autumn of 1916.
With pleasant flying characteristics and good manoeuvrability, the aircraft proved very successful.
The Pup was eventually outclassed by newer German fighters, but it was not completely replaced on the Western Front until the end of 1917.
Remaining Pups were relegated to Home Defence and training units.
The Pup's docile flying characteristics also made it ideal for use in aircraft carrier deck landing and takeoff experiments. In 1915, Sopwith produced a personal aircraft for the company's test pilot Harry Hawker, a single-seat, tractor biplane powered by a seven-cylinder 50 hp Gnome rotary engine.
This became known as Hawker's Runabout; another four similar aircraft have been tentatively identified as Sopwith Sparrows.
Sopwith next developed a larger fighter that was heavily influenced by this design, though more powerful and controlled laterally with ailerons rather than by wing warping.
The resulting aircraft was a single-bay, single-seat biplane with a fabric-covered wooden framework and staggered equal-span wings.
The cross-axle type main landing gear was supported by V-struts attached to the lower fuselage longerons. The prototype and most production Pups were powered by the 80 hp (60 kW) Le Rhône 9C rotary engine. Armament was a single 0.303 inch (7.7 mm) Vickers machine gun synchronized with the Sopwith-Kauper synchronizer.
A prototype was completed in February 1916 and sent to Upavon for testing in late March.
The Royal Naval Air Service (RNAS) quickly ordered two more prototypes, then placed a production order. Sopwith was heavily engaged in production of the 1½ Strutter, and produced only a small number of Pups for the RNAS. Deliveries commenced in August 1916.
The Royal Flying Corps (RFC) also placed large orders for Pups. The RFC orders were undertaken by sub-contractors Standard Motor Co. and Whitehead Aircraft. Deliveries did not commence until the beginning of 1917.
A total of 1,770 Pups were built by Sopwith (96), Standard Motor Co. In May 1916, the RNAS received its first Pups for operational trials with "A" Naval Squadron. The first Pups reached the Western Front in October 1916 with No. 8 Squadron RNAS, and proved successful, with the squadron's Pups claiming 20 enemy machines destroyed in operations over the Somme battlefield by the end of the year.
The first RFC Squadron to re-equip with the Pup was No. 54 Squadron, which arrived in France in December.
The Pup quickly proved its superiority over the early Fokker,
Halberstadt and Albatros biplanes.
After encountering the Pup in combat, Manfred von Richthofen said, "We saw at once that the enemy aeroplane was superior to ours."
The Pup's light weight and generous wing area gave it a good rate of climb.
Agility was enhanced by installing ailerons on both wings.
The Pup had half the horsepower and armament of the German Albatros D.III, but was much more manoeuvrable, especially over 15,000 ft (4,500 m) due to its low wing loading.
Ace James McCudden stated that "When it came to manoeuvring, the Sopwith [Pup] would turn twice to an Albatros' once ... it was a remarkably fine machine for general all-round flying.
It was so extremely light and well surfaced that after a little practice one could almost land it on a tennis court." However, the Pup was also longitudinally unstable.
At the peak of its operational deployment, the Pup equipped only four RNAS squadrons (Nos. 3, 4, 8 and 9), and three RFC squadrons (Nos. 54, 46 and 66). By the spring of 1917, the Pup had been outclassed by the newest German fighters.
The RNAS replaced their Pups, first with Sopwith Triplanes, and then with Sopwith Camels.
The RFC soldiered on with Pups, in spite of increasing casualties, until it was possible to replace them with Camels in December 1917.
Home Defence duties Pup with 100 hp Gnome Monosoupape engine The raids on London by Gotha bombers in mid-1917 caused far more damage and casualties than the earlier airship raids.
The ineffective response by British interceptor units had serious political repercussions.
In response, No. 66 Squadron was withdrawn to Calais for a short period, and No. 46 was transferred for several weeks to Sutton's Farm airfield near London.
Two new Pup squadrons were formed specifically for Home Defence duties, No.
112 in July, and No. 61 in August. The first Pups delivered to Home Defence units utilised the 80 hp Le Rhône, but subsequent Home Defence Pups standardised on the more powerful 100 hp Gnome Monosoupape, which provided improved rate of climb.
These aircraft were distinguishable by the addition of vents in the cowling face.
Shipboard use Sqn Cdr E. H. Dunning attempting a landing on HMS Furious in a Sopwith Pup (August 1917) Sopwith Pups were also used in many pioneering carrier experiments.
On 2 August 1917, a Pup flown by Sqn Cdr Edwin Dunning became the first aircraft to land aboard a moving ship, HMS Furious. Dunning was killed on his third landing when the Pup fell over the side of the ship.
The Pup began operations on the carriers in early 1917; the first aircraft were fitted with skid undercarriages in place of the standard landing gear.
Landings utilised a system of deck wires to "trap" the aircraft. Later versions reverted to the normal undercarriage. Pups were used as ship-based fighters on three carriers: HMS Campania, Furious and Manxman.
A number of other Pups were deployed to cruisers and battleships where they were launched from platforms attached to gun turrets.
A Pup flown from a platform on the cruiser HMS Yarmouth shot down the German Zeppelin L 23 off the Danish coast on 21 August 1917.
The U.S. Navy also employed the Sopwith Pup with famed Australian/British test pilot Edgar Percival testing the use of carrier-borne fighters. In 1926, Percival was catapulted in a Pup off the battleship USS Idaho at Guantanamo Bay, Cuba.