Bristol Blenheim Mk.IVF
BRISTOL TYPE 149 BLENHEIM IV - The Bristol 149 was developed in 1935 to Specification G.24/35 for a general recon-naissance and coastal bomber, being basically a Bristol Blenheim I airframe with nose length-ened by 3 ft (0.91) to provide space for a navigator/radio operator ahead of pilot. Initially named Bolingbroke I and 134 ordered to Specification 11/36. Prototype (Bristol Blenheim I K7072 converted) flown September 24, 1937, and entered production after changes to nose shape and introduction of long range tanks in wings. Renamed Bristol Blenheim IV for RAF service; Bolingbroke name retained for Canadian production versions.
Bristol Blenheim III: Projected variant of Bristol Blenheim I with Bristol Blenheim Mk IV long nose but without extra fuel tankage of Mk IV.
Bristol Blenheim IV: Contracts for 312 with Bristol in 1937-38, plus 750 built by Avro at Chadderton and 2,060 by Rootes Securities at Speke and Blythe Bridge. Two 920 hp Mercury XV engines. Initial armament of one fixed forward firing Browning and one Lewis or Vickers K gun in dorsal turret, both of 0.303-in (7.7-mm) calibre, later one gimbal-mounted nose gun, one or two rear-ward-firing Brownings in blister under nose and two Vickers 'K' or Browning guns in dorsal turret; bomb load 1,000 lb (454 kg) internal and 320lb (145 kg) external. Deliveries began March 1939, to No 90 Squadron; equipped 18 RAF squadrons by August 1939 and one aircraft of No 139 Sqn flew first RAF sortie of World War II to cross enemy lines, on September 3, 1939. Six Bristol Blenheim IV squadrons attached to BEF in France, 1939-41. Used extensively for day and night bombing and reconnaissance operations from the UK and in North Africa and Greece. Twelve Bristol Blenheim IVs (ex-RAF) supplied to Finnish Air Force, 1940, and ten built under licence in Finland, used along-side Mk Is in Winter War and Continuation War. Twelve (ex-RAF) supplied to Greece, October 1939-February 1940.
Bristol Blenheim IVF: Bomber Bristol Blenheims adapted to serve as long-range fighters, primarily with Coastal Command squadrons in 1940, carrying a pack of four fixed forward-firing 0.303-in (7,7-mm) guns under the fuselage.
Max speed, 266 mph (428 km/h) at 11,800 ft (3,597 m). Cruising speed, 198 mph (319 km/h). Initial rate of climb, l,500ftlmin (7.82 m/sec). Service ceiling, 27,260 ft (8,309 m). Max range, 1,460 mis (2,350 km) at 169 mph (272 km/h). Empty weight, 9,790 Ib (4,445 kg). Gross weight, 14,500 Ib (6,583 kg). Span, 56ft 4 in (17.17 m). Length, 42ft 7 in (12.98 m). Wing area, 469 sqft (43.57 m2).