The Bristol Blenheim I entered squadron service with the Royal Air Force in March 1937. It was the first modem all-metal cantilever monoplane with stressed skin construction to enter service with the RAF. With a top speed of 260mph, it was a quantum leap over the Hawker Hind (top speed 180mph) which was then the standard service light bomber. As it was swifter even than the service's standard fighters, the Gloster Gauntlet (230mph) and the Gloster Gladiator (253mph), it at last spelled the end to the biplane era for the RAF.

The Blenheim I had been developed from the Type 135, a private venture design by Frank Barnwell, Chief Designer of the Bristol Aeroplane Company, for a twin-engined light commercial transport -- a 1930s "biz-jet" so to speak. Lord Rothermere, the owner of Daily Mail, had ordered one example which was built as the Type 142. Named "Britain First," it was test-flown on 12 April 1935. In tests at the RAF's experimental establishment at Martlesharn Heath it proved faster than every RAF type. bomber or fighter, then in service. Naturally the RAF was keenly interested in such an aircraft. After the prototype was given to the RAF by its owner, a three-seat light bomber version with a 1,000lb payload was ordered off the drawing board, with no prototype, as the Type 142M.

Some 1,280 Blenheim Is were built by Gloster at Filton, A. V. Roe at Chadderton, and Rootes Securities at Speke before production shifted to the improved, long-nosed version designated as the Blenheim IV in 1939. During the Munich Crisis sixteen Blenheim I equipped bomber squadrons were available for service in the United Kingdom. By 3 September 1939, only two squadrons still were flying the Blenheim I in England; the rest had converted to the Blenheim IV. Although no longer a front-line bomber, the Blenheim I had found a new role as fighter. Some 200 had been converted to two-seat fighter with the addition of a belly pack with four .303 Browning machine guns with 500 rounds each. As Blenheim IT's, these aircraft equipped six RAF fighter squadrons by the start of the war. Although no match for modern fighters, Blenheim IFs began to receive radar (ASV Mark III) even before the war started and pioneered the development of the RAF's night fighter force. A Blenheim IF scored the RAF's first radar assisted night kill on 23 July 1940. However, the vastly superior Beaufighter appeared in late 1940, and the Blenheim I was again superseded.

Although phased out of first-line service at home, Blenheim bombers had been sent to serve overseas in the Middle East and Far East. Eight RAF squadrons (including one with both the bomber and fighter versions) were still equipped with the type when Italy entered the war in June 1940. Blenheim Is saw action in Egypt, in Greece, and in the Sudan before they were replace( by Blenheim IVs and other types in late 1941. Although not obsolete, Blenheim Is were still in service with three RAF squadrons in Malaya and Burma when Japan entered the war in December 1941. This was the last hurrah of the Blenheim I with the RAF as the Japanese soon decimated these squadrons. But Blenheim Is continued to serve in the front line, albeit not with the RAF.

Finland

Even before the Blenheim I had been selected for productior by the British, Lithuania and Finland had expressed interest ir both purchasing and building it under license. In spite of its advanced design (for the day), the aircraft was still considered an "interim" type and the Air Ministry allowed Bristol to entet the foreign market. The Lithuania interest waned but, beginning in July 1937, 18 Blenheim Is were delivered to Finland in time to serve in the Winter War, along with 12 extra aircraft (plus 12 Blenheim IVs) diverted from RAF stocks in February 1940, License production of the Blenheim I at the "Valtion Lentokonetehdas" (Government Aircraft Factory) at Tampere began in April 1938. 45 Finnish built Blenheim Is (designated by the British as the Blenheim II and slightly modified with twc forward firing machine guns and strengthened landing gear) rolled off the assembly line before production ended in September 1944, along with 10 "long-nose" Blenheim IVs. The Blenheim I remained in first line service throughout the Continuation War, and, in contrast to the heavy casualties inflicted on other fronts, suffered only light losses. Thirty-seven were still in action at the time of the Soviet-Finnish truce. This unit appears in the Finnish air force of FitE/SE.

Yugoslavia

Yugoslavia was the next country to acquire a license to build the Blenheim I. Two pattern aircraft were delivered from Bristol in July 1936, and production began by Ikarus AD at Zemun (in the outskirts of Belgrade) with the first aircraft, of 50 planned, flying on 15 April 1939. Yugoslav production was severely handicapped by a lack of powerplants as a ready supply of Mercury engines was no longer available from the United Kingdom. Polish-license built versions of the Mercury were ordered (to be delivered by the Germans in 1940!) and an order for 100 Alfa Romeo 126 engines (the Italian license built version of the Bristol Perseus engine) was placed but never fulfilled.

As the Blenheim was desperately needed, the Yugoslav government, with the backing of the British government, bought 20 A. V. Roe built Blenheim Is which were delivered in February-March 1940. On the day Germany invaded Yugoslavia, 56 Blenheim Is were in service with two bomber regiments of the "Jugoslovensko Kraljevsko Ratno Vazduhoplovstu" (JKRV or Royal Yugoslav Air Force). Flying without fighter protection, these (along 4 others delivered before the end of hostilities) were massacred by the Bf 109Es of the Luftwaffe. A few survived to fly with the German controlled "Hrvatsko bojnozrakoplvstro" (Croatian Air Force) of which two lasted to serve with the reformed Yugoslav Air Force after the war. Balkan Front includes a Bien I air unit in the Royal Yugoslav Air Force.

Turkey

Turkey ordered 12 Blenheim Is which were delivered by sea and air in 1937-1938. 18 additional aircraft were purchased and received by February 1939. During 1940, 10 more ex-RAF Blenheim Is were supplied by Britain. The Blenheim I (along with Blenheim IVs and Vs acquired during the war) remained in Turkish service until 1948. Turkey has a Bien I counter in WitD. Between June 1939 and January 1940, 40 Blenheim Is were delivered to the "Fortele Aeriene Regale ale Roumanieri" (FARR or Royal Romanian Air Force) by the British as part of a diplomatic effort to buy Romania's neutrality. They were assigned to three long-range reconnaissance squadrons but, now flying for the Axis, saw action on the Eastern Front, in ever- dwindling numbers, until 1944. A Blen I counter representing these aircraft appears in Fire in the East.

Greece

The final foreign country to receive the Blenheim I was Greece. When Italy invaded in October 1940, 12 Blenheim IVs were in service with the Royal Hellenic Air Force. Six Blenheim Is were transferred from the RAF to make up losses suffered and these along with Blenheim I equipped RAF squadrons fought to the end, first against the Regia Aeronautica and then against the Luftwaffe. These aircraft form part of the Greek mixed bomber unit in Balkan Front.

A ground-breaker when it entered service in 1937, the Blenheim I was clearly obsolescent by the time World War II started. With weak defensive armament and armor protection, it was easy prey to enemy fighters wherever it served. Nevertheless it helped the RAF in its transition from the traditional biplane to the modem high speed monoplane, and served faithfully on all fronts until replaced by its more modem successors. Designed as a light bomber, it made history as a radar equipped night fighter. For these reasons, and, as one of the few warplanes in the Second World War to serve as a first-line for both the Allies and the Axis, the Blenheim I has earned its place in history.

Bristol Blenheim I

Powerplants: two 840hp Bristol Mercury Vill nine-cylinder radial air-cooled engines
Service Ceiling 25,500 ft
Maximum Speed: 265 mph at 15,000 ft
Climb Rate: 1, 1540 ft/min
Fuel: 280 Imp. gal
Range: 920 miles at 165 mph
Armament: 1 x .303 caliber Browning mg forward firing and 1 x .303 caliber Vickers "K" mg in Bristol dorsal turret. Blenheim IF added 4x.303 caliber Browning mg with 500rpg forward firing in ventral pack.
Bombload: 2x 500lb bombs or 4x 250 lb bombs
Weight: 8,839 lb empty; 13, 100 lb max take-off
Crew: Pilot, navigator/bombardier, wireless operator/gunner

Bibliography

Axworthy, Mark (with Cornel Scafes & Cristian Craciunoiu); Third Axis Fourth Ally; 1995.
"Bristol's Trim Twins," Air Enthusiast Twenty-Eight (July- October 1985).
Green, William; War Planes of the Second World War-Fighters-Volume Two; 1964.
Green, William; Famous Bombers o the Second World War-Volume Two; 1960.
Jerin, Zoran; "The Blenheim in Yugoslavia," Air Enthusiast Sixteen (August-November 1981).
Moyes, Philip J. R.; "The Bristol Blenheim F in Aircraft in Profile- Volume 4; Martin C. Windrow, General Editor; 1968.
Stenman, Kari; "Staying Power-The Bristol Blenheim in Finnish Service;" Air Enthusiast No. 54 (Summer 1994).
Thetford, Owen; Aircraft of the Royal Air Force Since 1918; 1968.