Bristol 142M Blenheim I production
Bristol 142M Blenheim I production at Filton with prototype K7033 in foreground.


When Lord Rothermere, owner of the Daily Mail, first challenged the British Aircraft Industry to build a high-speed 6-passenger aircraft, it was his ambition to see Britain build 'the fastest commercial aeroplane in Europe, if not the world'. The year was 1934, and the German's led the world in high-speed designs and in addition to his motivation to recapture the title of the ‘fastest civilian aircraft’, he also wanted to own one for himself.
Bristol Aeroplane Company had been working on a twin-engine monoplane design, designated Bristol Type 135 and it was this that was further developed and adapted to produce what became the Bristol Type 142. 
Rothermere himself, placed an order for a single Bristol Type 142 with a 50% deposit and the balance payable upon the aircraft’s first flight.
The Bristol Type 142, christened ‘Britain First’, had its maiden flight at Filton on 12th April 1935, and the subsequent tests soon proved the aircraft to be much faster than predicted, so much so that it even outstripped all current RAF fighters.  The success of the Bristol Type 142, and its high performance resulted in immediate interest in a military version.
Designated Bristol Type 142M Blenheim, it differed slightly in that the wing was raised to allow a bomb-bay in the lower fuselage and a bomb-aiming station which was provided in the nose.  Further military equipment and defensive armaments were also installed whilst there were additional modifications to the tail plane and elevators.
The type was ordered ‘off the drawing board’ against Specification 28/35 with the first and only prototype (K7033) flying for the first time on 25th June 1936.
An initial contract for 150 aircraft followed in September 1935, whilst in addition to the RAF production, export orders were also received from Finland, Turkey and Yugoslavia. Licenced production was negotiated for Finland and Yugoslavia aircraft.
By the end of 1936, some 1,568 aircraft were on order and with contract production in the UK being undertaken by AV Roe & Co Ltd  at Chadderton and by Rootes Securities Ltd in Speke.


Bristol 142M Blenheim I K7059
Air to air photograph of RAF Bristol 142M Blenheim I K7059


The type was subsequently developed into the Bristol Type 149 Bolingbroke (Blenheim IV), Bristol Type 152 Beaufort and the Bristol Type 160 Bisley (Blenheim V), which are described separately elsewhere on this website.


Although arguably obsolescent against the best German fighters, the Bristol Blenheim gave most valuable service on operations in the early part of the Second World War.


The production numbers are widely quoted as 1,134 in the UK (634 Bristol, 250 AV Roe & Co Ltd, 250 Rootes Securities) plus 45 in Finland and 16 in Yugoslavia for a total of 1,195.


The Bristol Blenheim IF was a long-range night-fighter version, with a pack of 4 x 0.303 forward firing machine guns mounted under the fuselage and around 200 aircraft were converted to this role.


A single Blenheim I was converted to Blenheim II. It was fitted with long-range fuel tanks and had a maximum weight of 14,000 lb thereby allowing for an increased bomb load to be carried. This aircraft led to the Bristol Type 149 Bolingbroke (Blenheim IV), which was built in the UK and Canada and is described separately.



Specification (Blenheim 1)

Powerplant Two 840 hp Bristol Mercury VIII
Span 56 ft 4 in
Maximum Weight 12,250 lb
Capacity  Three crew (pilot, navigator / bomb aimer, gunner). Fixed forward firing Browning gun in port wing, one Lewis gun in dorsal turret, internal bomb load 1,000 lb. The Blenheim IF carried four additional forward firing Browning machine guns in an under-fuselage pannier. 
Maximum Speed 285 mph
Endurance / Range       1,125 miles


Numbers built

Blenheim I                   A total of 1,195 Blenheim I aircraft were built including licence production in Finland and Yugoslavia. See also Bristol 149 Blenheim IV / Bolingbroke, Bristol 152 Beaufort and Bristol 160 Bisley / Blenheim V.



Blenheim I                   No original Blenheim I aircraft survive.
Bolingbroke Mk IVT (RCAF10201) This aircraft was rebuilt at Duxford, flying in May 1993. Following an accident in August 2003 the aircraft was again rebuilt, this time with a Blenheim I nose, flying in November 2014, painted as Blenheim I L6739.


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