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Aircraft of the Royal Air Force

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 Blenhein 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 fighters.

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 success.

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.
 
Bristol Blenheim IF Specifications
Type Fighter / Fighter Bomber
Power Plant 2 x Bristol Mercury VIII 840hp radial engines
Unladen weight 8,840lb (4,100 kg)
Laden weight 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)
Cruising Speed 215 mph (346 kph) @ 15,000 ft (4,572 m)
0 - 5,000 ft (1,524 m) 3.9 minutes
Max range 1,050 miles (1,690 km)
Service Ceiling 24,600 ft (7,498 m)
Armament (Port Wing) 1 x .303 Browning machine gun
Armament (C.Fairing) 4 x Browning machine guns
Armament (Turret) 1 x Vickers K 303 machine gun
Wingspan 56ft 4in (17.17m)
Length 39ft 9in (12.12m)
Height 9ft 10in (3.0m)
Wing Area 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.



The Battle of Britain - 1940 website Battle of Britain Historical Society 2007