Bristol Berkeley

Bristol Aeroplane Company

Industry	Aerospace
Founded	1910
Headquarters	United Kingdom
Products	Aircraft

The Bristol Berkeley was developed in response to a British government requirement for a single-engine bomber capable of operating during day or night. Only three examples of this two-seat biplane were constructed, with no subsequent production contract awarded.

Development

In August 1923, the British Air Ministry issued Specification 26/23, seeking designs for a two-seat day or night bomber powered by a single Rolls-Royce Condor engine. The Bristol Aeroplane Company submitted the Berkeley, primarily designed by W.T. Reid, with final input from their chief designer, Frank Barnwell. This aircraft featured an all-metal framework covered with fabric and was a three-bay biplane with equal-span wings that were neither staggered nor swept. Both upper and lower wings incorporated Frise-type ailerons. The wing structure combined rolled steel and duralumin materials.

The fuselage construction utilised steel tubing with a rectangular cross-sectional shape. The pilot occupied an open cockpit positioned ahead of the wing's leading edge, while the gunner/observer was seated further back in an open cockpit equipped with a Scarff ring mounting for a .303 in (7.7 mm) Lewis Gun. Additionally, the gunner could assume a bomb aimer role by lying prone on the floor of the aircraft. The horizontal stabiliser was mounted atop the fuselage and supported underneath, featuring elevators with balance surfaces extending beyond the fixed tailplane. The rudder was tall and horn-balanced, designed with smooth integration into the fin for aerodynamic refinement. The undercarriage had a wide stance, attached beneath the centre section interplane struts of the wings and braced to the fuselage.

Powered by a 650 hp (490 kW) Condor engine driving a two-blade propeller, the Berkeley included a nose-mounted radiator placed beneath the propeller shaft following guidance from the Air Ministry. To expedite completion, the Ministry recommended that wooden wings be fitted to the first two Berkeleys out of three ordered, reserving all-metal wings for the third aircraft. The second and third machines were required to use Leitner-Watts metal airscrews. The maiden flight took place on 5 March 1925.

Significantly, the Type 90 Berkeley was Bristol's first design to be assigned a type number at the inception of its development rather than retrospectively.

Operational history

The initial Berkeley underwent evaluation trials at RAF Martlesham Heath starting in May 1925 and remained there until November of the same year. Other contenders vying for production contracts included the Handley Page Handcross, the Hawker Horsley, and the Westland Yeovil. Among these, the Handcross and Berkeley were the larger aircraft, which led to their consideration as more appropriate for night bombing missions. However, based on insights gained from operating the Avro Aldershot, the Air Ministry had already concluded that single-engine planes were unsuitable for night bombing tasks. Consequently, despite competition, only the Horsley was selected, fulfilling the day bomber role.

The Air Ministry accepted the second Berkeley in December 1925, followed by an all-metal third model in June of the following year. Each of these three aircraft was assigned to the Royal Aircraft Establishment (RAE) for experimental flight testing. During this period, the second Berkeley participated in comparative trials to evaluate a four-blade wooden propeller against its original two-blade steel counterpart. Notably, one of these three Berkeleys remained operational with the RAE as late as 1930.