Following the release of
Air Ministry Specification F.7/30 for a single-seat day and night fighter, eight companies proposed twelve designs and three, including Blackburn Aircraft, received contracts to produce a prototype. Blackburn's design, the F.3, was a single-bay
biplane of unequal wingspan and with an unusual configuration, the upper wing being mounted approximately halfway up the
stressed-skin fuselage and the lower wing about two feet below it, the gap being occupied by an enclosure for the condenser of the evaporatively-cooled Goshawk III engine. The undercarriage was attached to the front spar of the lower wing, with diagonal struts transmitting the landing loads to the fuselage
longerons. The wheels were fitted with spats but these were later removed. Four Vickers machine-guns were fuselage mounted, two in mid-position on the fuselage and the other two on either side of the top of the condenser housing. ==Operational history==