Bristol Blenheim
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| Blenheim (Types 142M, 149, 160) | |
|---|---|
 Work takes place on a Blenheim Mk. IV |
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| Type | Light bomber/fighter |
| Manufacturer | Bristol Aeroplane Company |
| Designed by | Frank Barnwell |
| Maiden flight | 12 April 1935 |
| Introduction | 1937 |
| Retired | 1944 (United Kingdom) 1956 (Finland) |
| Primary users | Royal Air Force Royal Canadian Air Force Finland Yugoslavia |
| Number built | 4,422 |
The Bristol Blenheim was a British light bomber aircraft designed and built by the Bristol Aeroplane Company that was used extensively in the early days of the Second World War. It was later adapted into a successful long-range fighter and night fighter. A Canadian-made variant named the Bolingbroke was used as an anti-submarine and training aircraft. It was one of the first British aircraft to have all-metal stressed skin construction, to utilise retractable landing gear, flaps, powered gun turret and variable-pitch propellers.
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[edit] Design and development
In 1934 Lord Rothermere, owner of the Daily Mail, issued a challenge to the British aviation industry to build a high-speed aircraft capable of carrying six passengers and two crew members. At the time German firms were producing a variety of high-speed designs that were breaking records, and Rothermere wanted to recapture the title of fastest civilian aircraft in Europe. Bristol had been working on a suitable design as the Type 135 since July 1933, and further adapted it to produce the Type 142 to meet Rothermere's requirements.
When it first flew as Britain First at Filton on 12 April 1935[1] , it proved to be faster than any fighter in service with the Royal Air Force at the time.[1] The Air Ministry was obviously interested in such an aircraft and quickly sent out Specification B.28/35 for prototypes of a bomber version; the Type 142M (M for military). The main changes were to move the wing from a low-wing to a mid-wing position, allowing room under the main spar for a bomb bay. The aircraft was all-metal with two Bristol Mercury VIII air-cooled radial engines, each of 860 hp (640 kW). It carried a crew of three – pilot, navigator/bombardier and telegraphist / air gunner. Armament comprised a single forward-firing 0.303 inch (7.7 mm) Browning gun outboard of the port engine and a 0.303 inch Lewis gun in a semi-retracting Bristol Type B Mk.I dorsal turret firing to the rear. From 1939 onwards, the Lewis gun was replaced by the more modern Vickers K of the same calibre. A 1,000 lb (454 kg) bomb load could be carried in the internal bay.
To achieve its relatively high speed, the Blenheim had a very small fuselage cross-section. Pilot's quarters on the left side of the nose were so cramped that the control yoke obscured all flight instruments while engine instruments eliminated the forward view on landings. Most secondary instruments were arranged along the left side of the cockpit with essential items like propeller pitch control actually placed behind the pilot where they had to be operated by feel alone. Like most contemporary British aircraft, the bomb bay doors were kept closed with bungee cords and opened under the weight of the released bombs. Because there was no way to predict how long it would take for the bombs to force the doors open, bombing accuracy was consequently poor.[2]
The aircraft was ordered directly from the drawing board with the first production model, known at the time as the Bolingbroke (pronounced Bolling-brook), serving as the first and only prototype[3]. The name then became Blenheim Mk.I with subsequent deliveries started in March 1937, with 114 Squadron being the first squadron to receive the Blenheim.[3] The aircraft would prove to be so successful that it was licensed by a number of countries, including Finland and Yugoslavia. Other countries bought it outright, including Romania, Greece and Turkey. Total production of the Blenheim in England amounted to 1,351 Mk Is.
[edit] Variants
Work on an extended range reconnaissance version started as the Blenheim Mk.II, which increased tankage from 278 to 468 gallons, but only one was completed. Another modification resulted in the Blenheim Mk.III, which lengthened the nose to provide more room for the bombardier. This required the nose to be "scooped out" in front of the pilot to maintain visibility during takeoff and landing. However both of these modifications were instead combined, along with a newer version of the Mercury engine with 905 hp (675 kW) and the turret acquired a pair of Brownings instead of the Vickers K; creating the Blenheim Mk.IV. In total, 3,307 would eventually be produced.
Another modification led to a long range fighter version; the Blenheim Mk.IF. For this role, about 200 Blenheims were fitted with a gun-pack under the fuselage for four 0.303 in Brownings. Later, the Airborne Intercept (AI) Mk III or IV radar would be fitted to some aircraft in use as night fighters, becoming the first British fighters equipped with radar. Their performance was marginal as a fighter, but sufficient for the task in hand and they served before the advent of more sophisticated machines. About 60 of Mk IVs were also equipped with the gun pack as the Mk.IVF and were used by Coastal Command to protect convoys from German long-range bombers.
The last bomber variant was conceived as an armoured ground attack aircraft, with a solid nose containing four more Browning machine guns. Originally known as the Bisley, the production aircraft were renamed Blenheim Mk.V and featured a strengthened structure, pilot armour, interchangeable nose gun pack or bombardier position and, yet another Mercury variant, this time with 950 hp (710 kW). The Mk.V was ordered for conventional bombing operations, with the removal of armour and most of the glazed nose section. The Mk V or Type 160, was used primarily in the Middle East and Far East.
The Blenheim would serve as the basis for the Beaufort torpedo bomber, which itself led to the Beaufighter; the lineage performing two complete circles of bomber to fighter.
[edit] Bolingbroke
The longer range also fulfilled a Canadian requirement for a maritime patrol aircraft. Consequently, Fairchild Aircraft Ltd. (Canada) of Quebec started production of the Blenheim Mk.IV as the Bolingbroke, nicknamed the "Bolly". After a small run of aircraft constructed to British specifications, as the Bolingbroke Mk.I, Fairchild switched production to the Bolingbroke Mk IV with American instruments and equipment. These versions also included anti-icing boots and a dinghy. Some of these aircraft served as bombers during the Aleutians campaign, but most of the 150 served in the intended role as patrol bombers on the Atlantic coast. Another 450 were completed as the Bolingbroke Mk IVT as trainers and saw extensive use in the Commonwealth Air Training Plan. One of the final variants was the Bolingbroke Mk IVW which was powered by two 634 kW (850-hp) Pratt & Whitney SB4G Twin Wasp Junior engines. A total of 676 Bolingbrokes was produced.
[edit] Operational history
By the start of the Second World War, fighter technology had eclipsed the Blenheim's speed advantage and it would only achieve moderate success in its intended role as a bomber. One of the greatest advantages that the Blenheim had over other fighter aircraft was its range. It could penetrate deep into enemy territory but it was vulnerable if it came into contact with any enemy fighters. With a top speed of only 263 mph (423 km/h) and cumbersome and slow in turning, it was soon eclipsed by other more modern types. Nonetheless, the Blenheim continued in frontline service throughout the early years of the conflict.
After France fell to Germany in June 1940, the Free French Air Force was formed at RAF Odiham in the form of Groupe Mixte de Combat (GMC) 1, consisting of a mixed bag of Blenheims and Westland Lysander liaison/observation aircraft, which eventually went to North Africa and saw action against the Italians and Germans.
[edit] Long-range fighter
The Bristol Blenheim was used by both Bomber and Fighter Commands. Some 200 Mk.I bombers were modified into Mk.IF long-range fighters with 600 (Auxiliary Air Force) Squadron based at Hendon, the first squadron to take delivery of these variants in September 1938. By 1939, at least seven squadrons were operating these twin engined fighters and within a few months some 60 squadrons had experience of the type. The Mk.IF proved to be slower and less nimble than expected and by 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 No. 23 Squadron RAF who had already operated the type under night time conditions had better success.
[edit] Night fighter
In the German night bombing raid on London, 18 June 1940, Blenheims accounted for five German bombers thus proving they were better suited in the nocturnal role. In July, No. 600 Squadron, by then based at RAF Manston, had some of its IFs equipped with AI Mk.III radar. With this radar equipment, a Blenheim from FIU at RAF Ford achieved the first success on the night of 2/3 July 1940, accounting for a Dornier Do 17 bomber. More successes came and, before long, the Blenheim was to prove invaluable in the night fighter role. Gradually, with the introduction of the Bristol Beaufighter in 1940-1941, its role was supplanted by its faster, better armed progeny.
[edit] Eastern service
Blenheims continued to operate widely in many combat roles until about 1943, equipping RAF squadrons in the UK and in British bases in Egypt, Iraq, Aden, India, Malaya, Singapore and Dutch East Indies. Many Blenheims were lost to Japanese fighters during the Malayan campaign and battles for Singapore and Sumatra. By that point, most fighters could carry similar bombloads at much higher speeds and the surviving examples were relegated to training duties. Bristol's intended successor to the Blenheim, the Buckingham, was considered inferior to the Mosquito, and did not see combat.
The final ground attack version - the Mk.V - first equipped 139 Squadron in June 1942. Eventually 13 squadrons - mainly in the Middle East and Far East - received this variant but operated them generally only for a few months. [4]
[edit] Finland
In 1936, the Finnish Air Force ordered 41 Mk.Is from Britain and two years later, they obtained a manufacturing license for the aircraft. Fifteen aircraft were constructed in Finland prior to the Winter War at the Valtion lentokonetehdas and a further 41 were constructed later on, bringing the total number up to 97 aircraft (75 Mk Is and 22 Mk IVs). The Finns obtained large supplies of ex-Yugoslavian spares from the Germans during the war.
The Finnish Blenheims flew 423 bombing missions during the Winter War, and some further 3,000 bombing missions during the Continuation War. Blenheim machine gunners also shot down five Soviet fighters. Half of the Blenheims were lost to all causes during the wars.
After the war, Finland was prohibited to fly bomber aircraft. However, some of the Finnish Blenheims continued in service as target tows until 1958.
[edit] Operators
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[edit] Survivors
There are currently no Blenheim or Bolingbroke aircraft that are airworthy. Two examples of the type are owned by the Aircraft Restoration Company in Duxford, Cambridgeshire. The first airworthy Blenheim had been rebuilt from a scrapped Bolingbroke over a 12-year period, only to be destroyed within a month of completion. A replacement Bolingbroke Mk.IVT was rebuilt to flying status in just five years and painted to represent a Blenheim Mk.IV in RAF wartime service. It began appearing at air shows and exhibitions in the UK, flying since May 1993 and was used in the 1995 film version of Shakespeare's Richard III. This aircraft crashed on landing 18 August 2004, and is presently undergoing an extensive repair.
In Canada, a number of other Bolingbrokes survived the war but were summarily consigned to the scrap heap. Postwar, enterprising farmers often bought surplus aircraft such as these for the scrap metal content, tires for farm implements, and even for the fuel remaining in the tanks. Some surviving examples in Canada of the Bolingbroke can be traced back to this period. The Canadian Warplane Heritage Museum in Hamilton, Ontario has been rebuilding a Bolingbroke to what is hoped to be airworthy status. The Commonwealth Air Training Plan Museum in Brandon, Manitoba has restored the exterior of one Bolingbroke, painting it in the Air Training Plan yellow color. This particular aircraft is on display at a location () on the Trans-Canada Highway in Brandon.
In Finland, the sole surviving original Blenheim in the world, a Mk.IV registered as BL-200 of the Finnish Air Force, is stored for restoration in the Aviation Museum of Central Finland. A project is underway to build a room for a public exhibition for this aircraft.[5][6]
In Greece a Bristol Blenheim Mk.IVF was recovered from the sea and moved to the Hellenic Air Force Museum for restoration.
[edit] Specifications (Bristol Blenheim Mk I & IV)
Data from British Warplanes of World War II [7]
General characteristics
- Crew: 3
- Length: 42 ft 7 in (12.98 m)
- Wingspan: 56 ft 4 in (17.17 m)
- Height: 9 ft 10 in (3.0 m)
- Wing area: 469 ft² (43.6 m²)
- Empty weight: 9,790 lb (4,450 kg)
- Loaded weight: 14,400 lb (6,545 kg)
- Powerplant: 2× Bristol Mercury XV radial engine, 920 hp (690 kW) each
- Propellers: Three-bladed Hamilton Standard propeller
Performance
- Maximum speed: 266 mph (231 knots, 428 km/h)
- Range: 1,460 mi (1,270 NM, 2,351 km)
- Service ceiling 27,260 ft (8,310 m)
- Rate of climb: 1,500 ft/min[citation needed] (7.6 m/s)
- Wing loading: 30.7 lb/ft² (150 kg/m²)
- Power/mass: 0.13 hp/lb (0.21 kW/kg)
Armament
- Guns:
- 1× .303 in (7.7 mm) Browning machine gun in port wing
- 1 or 2× .303 in Browning guns in rear-firing under-nose blister or Nash & Thomson FN.54 turret
- 2× .303 in Browning guns in dorsal turret
- Bombs:
- 4× 250 lb (110 kg) bombs or
- 2× 500 lb (230 kg) bombs internally, and
- 8× 40 lb (18 kg) bombs externally
[edit] See also
Related development
Comparable aircraft
Related lists
[edit] References
[edit] Notes
[edit] Bibliography
- Air Ministry Pilot's Notes: Blenheim. London: OHMS/Air Data Publications, 1939.
- Air Ministry Pilot's Notes: Blenheim V. London: OHMS/Air Data Publications, 1942.
- Barnes, C.H. Bristol Aircraft Since 1910. London: Putnam, 1970. ISBN 0-85177-804-6.
- Boiten, T. Bristol Blenheim. London: The Crowood Press, 1998. ISBN 1-86126-115-2.
- Bowyer, C. Bristol Blenheim. London: Ian Allen, 1984. ISBN 0-7110-1351-9.
- Keskinen, Kalevi et all. Suomen Ilmavoimien Historia 10, Bristol Blenheim. Loviisa: Painoyhtymä Oy, 2004. ISBN 952-99432-1-0.
- Jefford, C.G., RAF Squadrons. Shrewsbury: Airlife Publishing, 2nd edition, 2001. ISBN 1-84037-141-2
- Lake, J. Blenheim Squadrons of World War II. London: Osprey Publishing, 1998. ISBN 1-85532-723-6.
- Mackay, Ron. Bristol Blenheim in Action. Carrollton, Texas: Squadron/Signal Publications, 1998. ISBN 0-89747-209-8.
- March, Daniel J., ed. British Warplanes of World War II. London: Aerospace, 1998. ISBN 1-874023-92-1.
- Marttila, Jukka. Bristol Blenheim - Taitoa ja tekniikkaa. Vantaa, Finland: Blenimi-Publishing, 1989. ISBN 952-90017-0-3.
- Mason, Francis K. The British Bomber Since 1914. London: Putnam Aeronautical Books, 1994. ISBN 0-85177-861-5.
- Thomas, A. Bristol Blenheim (Warpaint No. 26). London: Hall Park Books, 2000. ISBN 1-84176-289-X.
- Warner, G. The Bristol Blenheim: A Complete History (2nd edition). London: Crécy Publishing, 2005. ISBN 0-85979-101-7.
[edit] External links
- RAF Bristol Blenheim history
- A history of No. 211 Squadron RAF in two world wars
- Blenheim Society
- Finnish Mk IV Blenheim restoration (more than 600 pictures linked)
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