BRISTOL TYPE 142M BLENHEIM I - The Bristol team headed by Frank Barnwell designed the Type 142M during 1935 as a three-seat light bomber derivative of the Type 142 Britain First, the major differences being raising the wing to a mid position to make room for a bomb-bay in the fuselage, adding nose and dorsal armament plus a bomb-aiming station in the nose, the raising and enlarging the tailplane. A contract for 150 Type 142Ms to Specification 28/35 was placed by the Air Ministry in September 1935 and the name Bristol Blenheim was adopted in April 1936.

Bristol Blenheim I: Production contracts for 150 in 1935 and 434 in 1936, and 134 in 1937 to make a total of 718 built by Bristol, plus 250 by Avro at Chadderton and 422 by Rootes Securities at Speke. Two 840 hp Bristol Mercury VIII engines. One fixed for-ward-firing 0.303-in (7.7-mm) Browning gun in port wing and one 0.303-in (7.7-mm) Lewis gun in Bristol B.I Mk I powered dorsal turret. Internal bomb-load, 1,000 Ib (454 kg). First production Bristol Blenheim I flown June 25, 1936; initial deliveries to No 114 (B) Squadron in March 1937, and 16 other home bomber squadrons and 13 overseas bomber squadrons equipped, 1-937-39. Bristol Blenheim I bombers out of front-line service in UK by September 1939 but operational overseas, notably in the Western Desert and Greek theatres. Bristol built 18 Bristol Blenheim Is for the Finnish Air Force (Ilmavoimat) in 1937-38, adapted to carry Swedish bombs and to operate on skis, supplemented early-1940 by 12 ex-RAF Bristol Blenheim Is, and Finland's Valtion Lentokonetehdas at Tampere built 45 Bristol Blenheim Is under licence, the type being operational in the Winter War and Continuation War with LLv 42, 44, 46 and other units. The Yugoslav government purchased two Bristol Blenheim Is in 1937 and a licence to build 50, of which 16 had been completed by Ikarus AD at Zemun by the time of the German invasion in 1941, being supple-mented by another 20 ex-RAF in 1940, some adapted to have two 20-mm forward firing cannon. A few of the Bristol Blenheim Is that survived the fighting in 1941 later served with the Croat Air Force. The Turkish gov-ernment purchased 30 Bristol Blenheim Is, deliv-ered late 1937-February 1939, and in November 1939, 13 ex-RAF machines were supplied to Romania.

Bristol Blenheim IF: About 200 bomber Bristol Blenheims adapted as twin-engined fighters, with a pack of four fixed forward-firing 0.303-in (7.7-mm) Browning guns under the fuselage. Initial deliveries to No 25 Sqn, December 1938, and used by several squadrons at home and overseas for day and night fighting. Some fitted with AI Mk III radar for operational trials, gaining a first success on 2/3 July 1940.

Bristol Blenheim II: A single Bristol Blenheim I (LI222) with long-range tanks and gross weight of 14,000 Ib (6,356 kg), with provision for extra bombs externally under inner wings.

Max speed, 285 mph (459 km/h). Cruising speed, 200 mph (322 km/h). Initial rate of climb, 1,540 ftlmin (7.82 m/sec). Service ceil-ing, 32,000 ft (9,754 m). Range, 1,125 mis (1,810 km). Empty weight, 8,100 Ib (3,677 kg). Gross weight, 12,250 Ib (5,561 kg). Span, 56ft 4 in (17.17 m) . Length, 39ft 9 in (12.12 m) . Wing area, 469 sqft (43.57 m2).

Photo	Description
	Drawing Blenheim Mk.IF
	Bristol Blenheim Mk. I of Finland

Bibliography

• "Encyclopedia of military engineering" /Aerospace Publising/
• "American warplanes of World War II" /under cor. David Donald/