The Blenheim Mk I entered RAF service in March 1937. It closely resembled the final prototype, other than the engines, which were changed to Bristol Mercury VIIIs, producing 850 hp. The Mk I had the distinctive short nose, with the front of the aircraft almost in line with the propellers. Armament was provided by one fixed forward firing .303in machine gun in the port wing, and another .303in machine mounted in a semi-retractable Bristol designed turret. By the time war broke out, the Blenheim Mk I had been withdrawn from service in Britain, and instead was equipping squadrons in North Africa and the Far East.
All versions of the Blenheim were awkward to get in and out of. The pilot and navigator had to lower themselves in via a hatch above the cockpit, and minor scrapes and cuts were common. The navigator/ bomb aimers position in the Mk I was cramped, with no space for a proper map table. However, the pilot did have excellent visibility. In all 1,280 Mk Is were built, production overlapping with the Mk IV.
A number of Blenheims were converted to act as long range escort fighters. This involved fitting a gun pod, containing four .303in Browning machine guns in the bomb bay. The Blenheim Mk IF was not a great success as a day fighter, not having the required speed. During 1940 it also served as night fighter, carrying some of the first Airborne Intercept radar, achieving some success in this role. However, the Blenheim was barely fast enough to catch German bombers, and was soon replaced by more suitable aircraft.
Introduction - Combat Record - Mk I - Mk IV - Mk V - Bisley - Bolingbroke - Stats - Picture Gallery