The first prototype of the Sopwith Tri-plane passed by the Experimental Department on May 28 1916, shortly after the Sopwith Pup had been approved.
The project was headed by the designer Herbert Smith. This new and very different plane was completed in a very short time and that was no small achievement, especially considering the radical changes made to its design and configuration.
Designed as a single-seat fighter, the Tri-plane derived its basic fuselage construction and fittings from the Pup. It also included the same tail unit but was equipped with an adjustable tailplane. Although the wing span was the same as the Pup (26ft. 6 in.) the Triplane had a smaller wing area and its structure weight was greater, thus needing a more powerful engine like the Clerget 9B.
The Triplane was initially armed with a single mounted synchronized Vickers machine gun.
Structurally, the Triplane was an ingenious creation, with its three narrow-chord wings all of which were fitted with ailerons and strong interplane struts that needed less rigging wires. The most desirable features of the Triplane was its increased field of vision for the pilot and its maneuverability.
The first prototype Triplane, serial N500 was flown on 28 May 1916 by Sopwith test-pilot Harry Hawker who dazzled those present by looping the aircraft three times within minutes after take off.
It was next sent to France in mid 1916 to undergo service trials with the Naval A Fighting Squadron at Furnes. The Tri-plane was an instant success with pilots and servicemen. It was garnered high praise for its exceptional rate of climb and high maneuverability and apparently was sent up on an interception mission within a quarter of an hour of its arrival in Furnes.