The Beardmore WB III was nothing more than a highly-modified, navalized version of the successful land-based Sopwith Pup single-seat, single-engine biplane fighter of 1916. The William Beardmore and Company firm was already under contract to produce the land-based Sopwith Pup, this under legal license, and developed the WB III for shipboard use by the Royal Naval Air Service during World War 1. First flight was recorded in 1917 and some 100 examples were ultimately produced.
Design of the WB III was conventional for biplane fighter aircraft of the time, keeping up with features as found on the Sopwith Pup. The engine was held in a forward compartment at the front of the slab-sided fuselage. A cylindrical engine cowling was fitted over the front engine facing for a more streamlined approach. The engine, a single nine-cylinder Le Rhone 9C series engine or a seven-cylinder Clerget (each delivering up to 80 horsepower), turned a two-bladed wooden propeller. The biplane wing arrangement featured straight parallel struts unlike the Sopwith Pup's staggered formation, necessitated by the Navy requirement for manually folding wings (space on aircraft carriers was always at a premium). Additionally, the undercarriage - consisting of two fixed single-wheeled members - could be removed by the ground crew for improved stowage while the tail was supported by a simplistic tail skid. The fuselage tapered off to the empennage to which was affixed a rounded vertical tail fin and applicable horizontal planes.
Performance from the available powerplant allowed for a top speed of up to 103 miles per hour with a service ceiling of up to 12,400 feet and a rate-of-climb equal to 534 feet per minute. Endurance time (essentially the aircraft's operational range) was listed at 2 hours and 45 minutes. The WB.III maintained a wingspan of 25 feet with a running length of 20 feet, 3 inches. She sat with an 8 foot, 1 inch height. On empty, she weighed in at 890lbs and could take off with a weight of up to 1,290 lbs. Armament was a single fixed, upward-firing .303 Lewis machine gun, firing through a cut-out section of the upper wing assembly.
The prototype WB III was accepted by the British military on February 7th, 1917. A contract for 100 production examples soon followed. Furthermore, the official British designation for the WB III family became "SB 3". The initial production models fell under the designation of SB 3F and covered some thirteen examples until supplanted by the revised SB 3D. The SB 3D sported a jettisonable undercarriage as well as emergency flotation equipment in a slightly lengthened fuselage.
The WB III served on only three Royal aircraft carriers, these being the HMS Furious, HMS Nairana and the HMS Pegasus. Japan became the only other notable operator of the WB III/SB 3 series.