William Beardmore and Co developed their W.B.III as a carrier version of the Sopwith Pup fighter with manually-folding mainplanes and folding main undercarriage members. 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.

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 (a modified Pup) was accepted by the British military on February 7th, 1917. A contract for 100 production examples soon followed under the official British designation of SB 3.

Armament comprised a single 7.7mm Lewis gun which fired upwards through a cut-out in the upper wing centre section, and the W.B.III could be fitted with either the seven-cylinder Clerget or nine cylinder Le Rhone 9C rotary, both of 80hp. The first 13 production W.B.IIIs had folding undercarriages similar to the prototype and were known as S.B.3Fs, but subsequent W.B.Ills had jettisonable undercarriages (S.B.3D) and flotation equipment.

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. One S.B.3D was used in an unsuccessful attempt to fly from the forecastle of the battle cruiser HMS Renown. Japan became the only other notable operator of the WB III/SB 3 series.

Beardmore SB 3F
Engine: 1 x Le Rhone 9C OR 1 x Clerget rotary, 80 hp
Length: 20 ft 3 in (6.16m)
Wingspan: 25.00ft (7.62m)
Height: 8 ft 1 in (2.47m)
Wing area: 22.57 sq.m / 242.94 sq ft
Maximum Speed: 103mph (166kmh; 90kts)
Maximum Range: 171miles (275km)
Rate-of-Climb: 534ft/min (163m/min)
Service Ceiling: 12,402ft (3,780m)
Armament: 1 x 7.7mm (0.303 caliber) Lewis machine gun
Accommodation: 1
Empty Weight: 891lbs (404kg)
Maximum Take-Off Weight: 1,290lbs (585kg)