The Bristol Blenheim originally was constructed
as a private venture. The Bristol Aeroplane Company in 1934 was ordered
to construct a high speed six to eight seater twin engined aircraft by
a Lord Rothermere as a civil aircraft. It was a low wing all metal monoplane
and in 1935 it managed 307mph at 14,000 feet, had excellent flying characteristics
and a retractable undercarriage. It is said that Lord Rothermere donated
the aircraft to the nation because of it was an aircraft ahead of its time.
It had a number change from G-ABCZ to K-7557 and in 1935 was submitted
to meet Specification B.28/35 which was called for at the time.
To meet the specified requirements of Specification
of B.28/35 the wings were raised to mid fuselage position, the Mercury
6.S.2 640hp radial engines were replaced by 840hp Mercury 8s and
it was accepted as the Blenheim Mk I light bomber. But by the time it would
be put into service as a war fighting machine, it was found to be slow
and would be vulnerable to enemy fighter attack aircraft. In 1938 the decision
was made to convert the Blenheim 1 to a long range fighter. But although
it was found to be just as cumbersome and its fire power was to prove quite
inadequate, the Air Ministry at the time thought that it was better to
put the aircraft into service than nothing at all.
Designated the Blenheim IF, the main difference
was the addition of a ventral pack of four .303 machine guns that were
manufactured by the Ashford workshops of the Southern Railway. Other armament
of the IF was a single wing mounted Browning machine gun and a Vickers
"K" gun and a semi-retractable hydraulically operated dorsal turret.
In all, there were some 200 Blenheim I
bombers converted to Blenheim IF's and the first squadron to take delivery
of these was 600 AAF Squadron based at Hendon, this was in September 1938.
By the time WWII broke out, seven squadrons were operating these twin engined
One of the greatest advantages that the
Blenheim had over other fighter aircraft was its range. It could penetrate
deep into enemy territory, that is provided that they did not come into
contact with any other enemy fighters. With only a top speed on 263 mph
(423 kph) and cumbersome and slow in turning it was to have the same
fate as the Defiant.
In May and June 1940 daylight Blenheim
losses was to cause concern for Fighter Command. It was then decided that
the IF would be relegated mainly to night fighter duties where 23 Squadron
who had already operated the IF under night time conditions had better
In the German night bombing raid on London
of June 18th, Blenheims accounted for five German bombers thus proving
they were better suited in the nocturnal role. In July, the 600 Squadron
from Manston had some of their IF's equipped with A1 Mk III radar and with
this equipment a Blenheim from FIU at Ford airfield achieved the first
success with this radar.
More successes came and before long the
Blenheim was to prove the backbone of Fighter Command's night fighter role.
The Bristol Blenheim was used by both Bomber and Fighter Commands.
||Fighter / Fighter Bomber
||2 x Bristol Mercury VIII
840hp radial engines
||8,840lb (4,100 kg)
||12,200 lb (5,534 kg)
|Max Speed (Sea Level)
||237 mph (381 kph)
|Max Speed (10,000 ft)
||263 mph (423 kph)
|Max Speed (15.000 ft)
||278 mph (447 kph)
||215 mph (346 kph) @ 15,000
ft (4,572 m)
|0 - 5,000 ft (1,524 m)
||1,050 miles (1,690 km)
||24,600 ft (7,498 m)
|Armament (Port Wing)
||1 x .303 Browning machine
||4 x Browning machine guns
||1 x Vickers K 303 machine
||56ft 4in (17.17m)
||39ft 9in (12.12m)
||9ft 10in (3.0m)
||469 sq ft (43.57 sq m)
Another version of the Blenheim was the Blenheim
IVF. This was a similar aircraft to the IF but was converted from the Blenheim
IVL long range bomber. This was to provide RAF Coastal Command with a long
range anti shipping strike fighter.
Similar modifications were made to the
IVL bomber as was done with the MK I. This being a four gun ventral pack,
reflector gunsight, armour plate protection for the pilot and self sealing
fuel tanks. An additional radio was also fitted to the IVF.
Extra power was provided by fitting Bristol
Mercury XV radial engines giving 995 hp, and the armament was the same
as for the IF.
Two Fighter Command stations also operated
IVF's as well as eight Coastal Command stations. These were 25 squadron
and 600 squadron. This was for shipping patrols over the North Sea and
the Thames Estuary.
Both Blenheims continued service well into
1941, but the IF's suffered many casualties and during the 1940-1941 period
they were slowly replaced by the Beaufighter which although still did not
have the performance of the single engined fighters, was an aircraft that
performed far better than the Blenheim.