Development and Design
In 1918, the British Air Ministry drew up specification A.2 (B) for the replacement of the Airco DH.10 medium bomber, despite the fact that the DH.10 Amiens had not yet entered service. In response, J.D North, chief designer of Boulton & Paul's aircraft department designed a twin-engined aircraft, the P.7 Bourges, powered, like most of the types designed to replace the DH.10, by two of the new ABC Dragonfly radial engines. The ABC was ordered off the drawing board by the Ministry and high hopes were held for it. The Bourges was a three-seat, three bay biplane with unstaggered wings of all-wooden construction. Three prototypes were ordered by the Air Ministry.
Delays in delivery of airworthy examples of the Dragonfly lead to the decision to fit the first prototype with the much less powerful (230 hp/172 kW), but reliable Bentley BR2 rotary engine, allowing a first flight as the Bourges Mk IIA in June 1919.
Frank Courtney demonstrated the Bourges at Hendon at the end of May 1919 for a reception for Commander Read who had led the crossing of the Atlantic by US seaplanes. The magazine Flight commenting on its aerobatic capabilities and general performance though having already flown about 3,500 miles.
It was fitted with Dragonflys in July, becoming the Bourges Mk IA,. Both the Bentley and ABC engined Bourges demonstrated excellent performance and manoeuvrability, being able to be looped and rolled with ease.
The second aircraft was fitted with a gulled upper wing to improve the field of fire for its gunners - the engines moved down to the top of the lower wing. Fitted with Dragonflys, it was designated the Bourges Mk IB. It would crash in 1919 and its structure reused for a different project. The third Bourges was also originally built as a Mk IB, but when Boulton Paul realised that the reliability problems with the Dragonfly could not be cured, it was refitted with BR2s, being redesignated Bourges Mk IIB.
In 1920-21 the third prototype, the Bourges P.7B F2905 was again re-engined, this time with 450 hp (336 kW) Napier Lion engines, and was flown both with the original straight upper wing (Bourges Mk IIIA) and with the gulled wing (Bourges Mk IIIB). While in this form it was superior to the other types planned as DH.10 replacements, the RAF had by this time abandoned the requirement, and the Bourges was used for extensive testing at the Royal Aircraft Establishment, Farnborough continuing in use until 1924.
Read more about this topic: Boulton Paul Bourges
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