Bristol Blenheim Light Bomber

Blenheim Mk.Is
Bristol Blenheim Light Bombers

The Blenheim was a development of the Bristol model 142 civil transport, that was faster than the R.A.F. fighters when it first appeared. It was the result of the initiative of Lord Rothermere, owner of the Daily Mail, who ordered a fast, twin-engined private transport plane, capable of carrying 6 passengers and 2 crew members. He wanted it to be the fastest commercial plane in Europe. It was. The Air Ministry immediately saw it's potential and began tests in 1935. The aircraft had to be substantially altered for military use. The wings were raised and the fusilage altered to accomodate a bomb load. It was first received in 1937, the Mk IV model was available in 1939.

Both models saw a great deal of use in the first three years of WWII. The MkI made the first Allied operational mission of the war flying a reconnaissance flight over Germany. The Blenheim Mk I, shown above, was used mostly as a light bomber, while the Mk IV model (shown below) was used as a light bomber, fighter, nightfighter, reconaissance aircraft and close-support aircraft depending on how it was equipped. All models of the Blenheim were very vulnerable to enemy fighters as they didn't have the power to evade them, and the rear-facing armament wasn't heavy enough to defend them properly. Early models had a blunt, glazed nose, while the Mk.IV and later Blenheims featured an elongated 'stepped' nose with an asymetric shape. Over 5500 were built, including 676 in Canada under the name "Bolingbroke".

Blenheim IV
Bristol Blenheim Mk.IV Light Bomber

Technical Details
The Mk.I bomber had a crew of 3 and used the 840 hp (618 kW) Bristol Mercury VIII radial engines with single-stage supercharger. Maximum speed was 260 mph (418km/h), with a ceiling of 27,280 ft (8300m) and a range of 1,215 mi (1810 km). It was armed with two 0.303 caliber machine guns, one in the port wing outboard of the engine and 1 in the rear turret (a Vickers K gun), and could carry 1,000 lb (454 kg) of bombs of assorted sizes (4x250 lb, 2x500 lb, etc.).

The Mk.IV variant had a crew of 3, and used the 995 hp Bristol Mercury XV radial engine. These engines gave it a maximum speed of 266 mph (428 km/h), a ceiling of 27,280 ft (8300 m) and a range of 1,215 mi (1810 km). The ground attack version mounted 5 machine guns and could also carry 1,325 lbs of bombs. It had the standard single machine gun in the port wing, a pair of rear firing 0.303 machine guns in a chin blister and a pair of machine guns in the rear turret. The Mk.IVF (fighter/attack plane) carried six 0.303 machine guns, four in a belly pack, 1 in the port wing and 1 in the rear turret. This model was also employed as a night-fighter using ground-controlled radar direction.

The Mk.V variant was the last in the line using the Bristol Mercury XXX radial engine with 950 hp (708 kW). This engine did not increase the speed at all, but gave it a ceiling of 31,000 ft (9450 m) and a range of 1600 miles (2575 km.). It was used mostly in the Far East theatre, but was withdrawn after nine months due to poor performance.



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Images From:
Mk Is - Richard Bickers. The Battle of Britain. Military Archive Research Service photo.
Mk IV - With permission of Herve Champain.

Information From:
Chris Chant, Aircraft of World War II. Prospero Books. 1999
Don Clark provided information on the positioning of the Blenheim guns. Check out his site on No. 211 Squadron RAF.