page_title: Bristol Blenheim
section_title: Production
hierarchical_section_title: Bristol Blenheim / Development / Production
caption_attribution_description: Imperial War Museum, Duxford, UK.
context_page_description: The Bristol Blenheim is a British light bomber aircraft designed and built by the Bristol Aeroplane Company which was used extensively in the first two years and in some cases throughout the Second World War. The aircraft was developed as Type 142, a civil airliner, in response to a challenge from Lord Rothermere to produce the fastest commercial aircraft in Europe. The Type 142 first flew in April 1935, and the Air Ministry, impressed by its performance, ordered a modified design as the Type 142M for the Royal Air Force as a bomber. Deliveries of the newly named Blenheim to RAF squadrons commenced on 10 March 1937.
  A development of the Type 142M was the Type 149 which Bristol named the Bolingbroke, retrospectively changed by the Air Ministry to Blenheim Mk IV and the Type 142M to the Blenheim Mk I. Fairchild Canada built the Type 149 under licence as the Bolingbroke. Blenheims Mk I and the Mk IV were adapted as fighters by the addition of a gun pack of four Browning .303 machine guns in the bomb bay. The Mk IV was used as a long range fighter and as a maritime patrol aircraft; both aircraft were also used as bomber/gunnery trainers.
context_section_description: In September 1935, an initial contract for 150 aircraft was placed. The Air Ministry had chosen to order the type directly from the drawing board, having been urgently sought as one piece of a wider and rapid expansion of the RAF. The first aircraft built of this production model, K7033, served as the only prototype; on 25 June 1936, K7033 conducted its first flight from Filton. The service name for the aircraft became Blenheim Mk I after the famous battle during the War of the Spanish Succession. On 10 March 1937, production deliveries to the RAF formally started; 114 Squadron became the first squadron to receive the Blenheim. On 13 January 1938, the Blenheim entered service with No. 30 Squadron, the first overseas squadron to receive the type; in early 1939, the first Blenheims arrived in India.
  From July 1936 onwards, various additional orders were placed for the Blenheim Mk I, including multiple orders for the export market. By the end of 1936, 1,568 aircraft were on order. In order to meet the demand, secondary assembly lines were established at Chadderton by Avro and at Speke by Rootes Securities. The aircraft was built under licence by overseas countries, including Finland, who completed a total of 55 aircraft, and Yugoslavia, which completed 16 aircraft with a further 24 in advanced stages of completion when Germany invaded Yugoslavia. Other countries also procured the Blenheim, including Romania, Greece and Turkey. By September 1939, orders for the Blenheim had risen to 2,088 aircraft. Total production of the Blenheim Mk I in England was 1,351 aircraft prior to the end of the production run in 1939; production had been terminated in favour of more advanced variants.
  The Blenheim production program saw several shifts in requirements and in capacity. A modified Blenheim design, given the name Bolingbroke, was manufactured under licence in Canada by Fairchild Aircraft. The Bolingbroke, which had been developed in response to Air Ministry Specification G.24/35 to procure a coastal reconnaissance/light bomber as a replacement for the Avro Anson, had substantial improvements that would serve as the basis for improved variants of the Blenheim. According to aviation author James D. Oughton, both the navigator's station and range limitations of the Blenheim Mk I had been subject to considerable criticism, thus an improved model of the aircraft was desired in order to rectify these shortcomings. On 24 September 1937, an experimental Blenheim Mk I, modified with an extended forward fuselage beyond its original stepless cockpit, smooth-fronted nose enclosure, made its first flight from Filton.
caption: Blenheim Mk I reconstruction by the Aircraft Restoration Co at Duxford, for the owners, Blenheim (Duxford) Ltd. The reconstruction is based upon a restored Bolingbroke airframe with restored Blenheim Mk I nose section with its "stepless cockpit".
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