Royal Air Force History

Bristol Blenheim

Part 1 - BRISTOL TYPE 142 ‘BRITAIN FIRST’

As early as 1933 the Bristol chief designer Frank Barnwell began to consider the possibility of a light civil aircraft able to carry six passengers and a crew of two. He also believed that the aircraft should be capable of a cruising speed of at least 250mph. To appreciate the scale his ambition, one need only consider that the fastest RAF fighter of the day, the single seat Hawker Fury II, was capable of only 223mph. The majority of the RAF’s other biplane fighters and light bomber types were considerably slower, most were incapable of even 200mph.

An all-metal monocoque monoplane, twin engined machine with a fully enclosed cabin was proposed and Bristol type number 135 was allocated to the design. Much consideration was given to the location of the wing and in parallel to research in America a low wing configuration was considered to give the best high-speed performance. Despite being given a type number, no moves were made to produce a prototype by the company.

The Bristol Aeroplane Company not only produced fine military aeroplanes such as the contemporary Bulldog or Bristol Fighter of First World War fame; it was also a major aero-engine manufacturer. While Barnwell finalised his design for the new aircraft, the engineers led by Roy Fedden, were busy producing a new six-cylinder radial engine with an expected maximum output of 500hp. The first test runs of this new sleeve valved engine, which became known as the Aqulia, began in September 1934. Barnwell anticipated using the Aqulia for the Type 135, which despite its obvious potential, was still firmly grounded on the drawing board.

Lord Rothermere, the prosperous proprietor of the Daily Mail national newspaper and an ardent supporter of British aviation then became unintentionally involved in the history of the Blenheim. He boasted over an editorial lunch that he intended to have the fastest commercial aircraft in Europe built to his personal requirement. He was no doubt aware of the claims emanating from the other side of the Atlantic about the new and very impressive Douglas airliner. The DC-1 could carry 12 passengers and cruise at 190mph (it was later developed into the world famous DC-3 Dakota). Although the Bristol Type 135 existed only as a series of drawings it was by no means a secret. The editor of the grandly titled Bristol Evening World, Robert Lewis, certainly knew of the design and its promised performance. He made Rothermere aware that plans for a machine matching his very requirements existed on paper. Lewis liased with Barnwell and Fedden at Bristols and on 26 March 1934 the company were advised that Rothermere would order a single Type 135. Later that same month a price of £18,500 was agreed and assembly of the sleek new aeroplane began.

Rothermere was well known for his outspoken criticism of the prevalent state of the British military and civil aircraft industry, indeed he had quite a reputation for making political points. Therefore, it must have been with some trepidation that Bristol’s agreed to provide one of the Air Ministry’s greatest critics with an aircraft that would out perform any aircraft in service with the RAF. Not wishing to upset their biggest customer the company approached the Air Ministry and appraised them of the order and the potential performance of the Type 135. It was received with some relief when not only did the Ministry not object, it was actually very enthusiastic about the project and followed its progress with interest.

Suitably encouraged and at the request of Barnwell, who had recognised the aircraft’s military potential, the construction of two prototypes was soon started. Rothermere’s aircraft was to be fitted with powerful 650hp Bristol Mercury engines driving fixed pitch propellers and the new designation Type 142 was applied. The other machine was given the type number 143. It had shared approximately 70% of its components with the Type 142 and although its fuselage was 3ft 5in shorter, it could accommodate eight passengers. The Type 143 was powered by the intended 500hp Aqulias and was fitted with two bladed propellers. Both machines had provision for a crew of two.

Even before the aircraft flew there was immediate interest in the new Bristol machines. The Finnish government expressed great interest in a militarised version of the Type 143 with Mercury VI engines and a detailed study to incorporate the necessary modifications was made by Bristol’s. Designated the Type 143F this new variant had provision for a dorsal Lewis machine gun and a forward firing 20mm Madsen cannon. Interchangeable nose and rear fuselage sections enabled it to be configured to perform a wide variety of roles including that of transport, ambulance and light bomber. None of this went unnoticed by the Air Ministry who expressed their interest in a bomber version for themselves. The first flight of the Type 142 took place on 12 April 1935 from Filton; Rothermere himself named this modern and attractive aircraft Britain First. Shortly afterwards the four bladed fixed pitch propellers were replaced with more efficient three bladed Hamilton Standard units. Rothermere must have been delighted with the aircraft’s performance and generously made a gift of the aircraft to the Air Ministry.

In June the aircraft began its acceptance trials at the Aeroplane and Armament Experimental Establishment (AAEE) at Martlesham Heath bearing the serial number K7557. There it caused a great deal of excitement, the test pilots had only recently completed trials of the decidedly old fashioned biplane, Bolton Paul Overstrand bomber, capable of a lamentable 148mph. Pilots enthused about the new aircraft, which had a considerable speed advantage over the RAF’s latest fighter the Gloster Gladiator. The situation would not be redressed until the arrival of the Hawker Hurricane fighter. On the 17 July, K7557 was badly damaged during a landing accident in the hands of an AAEE pilot. The undercarriage had failed to lock down and collapsed under load. Such was the official embarrassment that Rothermere was given his original investment of £18,000 as compensation.

Meanwhile the Type 143 remained on the ground until the Aqulia engines were tested in a Bulldog and it eventually flew in January 1936. Although interest was expressed from Imperial Airways no serious attempt was made to proceed with this civil version mainly because of the non-existence of a suitable variable pitch propeller. Possibly for this reason the Aqulia engine was cancelled in 1938. Despite this the Type 143 did achieve a very respectable 250mph while the Type 142 excelled at 307mph.

Civil applications were brushed aside by the urgent need to re-equip the RAF with modern military aircraft. Barnwell had already proposed a bomber version of the 142 to the Air Ministry. By moving the wing to a mid-mounted position he was able to provide room for an internal bomb bay in the fuselage which could accommodate four standard 250lb bombs. For defence, a dorsal turret mounting a single machine gun was sited just aft of the trailing edge and this could be partially retracted to reduce drag when not in use. A fixed .303 machine gun was mounted in the port wing for use by the pilot. Numerous other modifications were incorporated in the Type 142M; a cramped workstation for the bomb aimer was created in the nose section and the tail plane was raised to prevent it being blanked by the new wing position.

In August 1935 the company received an order for 150 Type 142Ms before the first flight of the prototype K7033. This act of faith in Bristol’s design ensured that the RAF at least had a modern light bomber in production at a time of great crisis. The name Blenheim was adopted but sadly Captain Frank Barnwell was killed in a light aircraft crash on 2 August 1938.

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