De Havilland Mosquito (Bomber versions)

This entry is about the bomber versions of the Mosquito. For details of the fighter versions, visit De Havilland Mosquito (Fighter) entry on the Fighter Aircraft wiki. For details of the reconnaissance versions, visit De Havilland Mosquito (Reconnaissance) entry on the Flying Eyes wiki.
The de Havilland DH.98 Mosquito is a British twin-engined, shoulder-winged multirole combat aircraft, introduced during the Second World War. Unusual in that its frame was constructed mostly of wood, it was nicknamed the "Wooden Wonder",Price, Nigel (ed.). "Mosquito: A Celebration of de Havilland's 'Wooden Wonder'." FlyPast Special. Stamford, Lincolnshire, UK: Key Publishing Ltd., 2009. p. 3. or "Mossie".Hanson, Dave. "deHavilland DH 98 Mosquito." warbirdalley.com. Lord Beaverbrook, Minister of Aircraft Production, nicknamed it "Freeman's Folly", alluding to Air Chief Marshal Sir Wilfrid Freeman, who defended Geoffrey de Havilland and his design concept against orders to scrap the project.Birtles, Philip. De Havilland Mosquito: The Original Multirole Combat Aircraft. Stroud, England: Fonthill Media, 2017. ISBN 978-1-78155-494-4. ch. 3. In 1941, it was one of the fastest operational aircraft in the world.Bowman, Martin. de Havilland Mosquito (Crowood Aviation series). Ramsbury, Marlborough, Wiltshire, UK: The Crowood Press, 2005. ISBN 1-86126-736-3. p. 21.
Originally conceived as an unarmed fast bomber, the Mosquito's use evolved during the war into many roles, including low- to medium-altitude daytime tactical bomber, high-altitude night bomber, pathfinder, day or night fighter, fighter-bomber, intruder, maritime strike, and photo-reconnaissance aircraft. It was also used by the British Overseas Airways Corporation as a fast transport to carry small, high-value cargo to and from neutral countries through enemy-controlled airspace.Sharp and Bowyer 1971, p. 338. The crew of two, pilot and navigator, sat side by side. A single passenger could ride in the aircraft's bomb bay when necessary.
The Mosquito FBVI was often flown in special raids, such as Operation Jericho – an attack on Amiens Prison in early 1944, and precision attacks against military intelligence, security, and police facilities (such as Gestapo headquarters). On 30 January 1943, the 10th anniversary of the Nazis' seizure of power, a morning Mosquito attack knocked out the main Berlin broadcasting station while Hermann Göring was speaking, taking his speech off the air.
The Mosquito flew with the Royal Air Force (RAF) and other air forces in the European, Mediterranean and Italian theatres. The Mosquito was also operated by the RAF in the Southeast Asian theatre and by the Royal Australian Air Force based in the Halmaheras and Borneo during the Pacific War. During the 1950s, the RAF replaced the Mosquito with the jet-powered English Electric Canberra. 
==Development==
By the early to mid-1930s, de Havilland had a reputation for innovative high-speed aircraft with the DH.88 Comet racer. The later DH.91 Albatross airliner pioneered the composite wood construction used for the Mosquito. The 22-passenger Albatross could cruise at 210 miles per hour (340 km/h) at 11,000 feet (3,400 m), 100 mph (160 km/h) faster than the Handley Page H.P.42 and other biplanes it was replacing.Stroud 1990, p. 369. The wooden monocoque construction not only saved weight and compensated for the low power of the de Havilland Gipsy Twelve engines used by this aircraft, but also simplified production and reduced construction time.Bowman 2005, p. 9.
==Air Ministry bomber requirements and concepts==
On 8 September 1936, the British Air Ministry issued Specification P.13/36, which called for a twin-engined, medium bomber capable of carrying a bomb load of 3,000 lb (1,400 kg) for 3,000 mi (4,800 km) with a maximum speed of 275 mph (445 km/h) at 15,000 ft (4,600 m); a maximum bomb load of 8,000 lb (3,600 kg) that could be carried over shorter ranges was also specified.Sharp and Bowyer 1971, p. 30. Aviation firms entered heavy designs with new high-powered engines and multiple defensive turrets, leading to the production of the Avro Manchester and Handley Page Halifax.Sharp and Bowyer 1971, p. 31.
In May 1937, as a comparison to P.13/36, George Volkert, the chief designer of Handley Page, put forward the concept of a fast, unarmed bomber. In 20 pages, Volkert planned an aerodynamically clean, medium bomber to carry 3,000 pounds (1,400 kg) of bombs at a cruising speed of 300 mph (485 km/h). Support existed in the RAF and Air Ministry; Captain R N Liptrot, Research Director Aircraft 3, appraised Volkert's design, calculating that its top speed would exceed that of the new Supermarine Spitfire, but counter-arguments held that although such a design had merit, it would not necessarily be faster than enemy fighters for long.Buttler 2004, pp. 76–77. The ministry was also considering using non-strategic materials for aircraft production, which, in 1938, had led to specification B.9/38 and the Armstrong Whitworth Albemarle medium bomber, largely constructed from spruce and plywood attached to a steel-tube frame. The idea of a small, fast bomber gained support at a much earlier stage than is sometimes acknowledged, though the Air Ministry likely envisaged it using light alloy components.Buttler 2004, pp. 74, 77.
==Bomber Variants==
On 21 June 1941 the Air Ministry ordered that 10 Mosquitos, ordered as photo-reconnaissance aircraft, should be converted to bombers. These 10 aircraft were part of the original 1 March 1940 production order and became the B Mk IV Series 1. W4052 was to be the prototype and flew for the first time on 8 September 1941.Bowman 2005, pp. 22–23.
The bomber prototype led to the B Mk IV, of which 273 were built: apart from the 10 Series 1s, all of the rest were built as Series 2s with extended nacelles, revised exhaust manifolds, with integrated flame dampers, and larger tailplanes.Jackson 2003, p. 15. Series 2 bombers also differed from the Series 1 in having an increased payload of four 500 lb (230 kg) bombs, instead of the four 250 pounds (110 kg) bombs of Series 1. This was made possible by cropping, or shortening the tail of the 500 pounds (230 kg) bomb so that these four heavier weapons could be carried (or a 2,000 lb (920;kg) total load). The B Mk IV entered service in May 1942 with 105 Squadron.
In April 1943 it was decided to convert a B Mk IV to carry a 4,000 lb (1,800 kg) Blockbuster bomb (nicknamed a Cookie). The conversion, including modified bomb bay suspension arrangements, bulged bomb bay doors and fairings, was relatively straightforward and 54 B.IVs were modified and distributed to squadrons of the Light Night Striking Force.Sharp and Bowyer 1971, pp. 306–307 27 B Mk IVs were later converted for special operations with the Highball anti-shipping weapon, and were used by 618 Squadron, formed in April 1943 specifically to use this weapon.Sharp and Bowyer 1971, pp. 74, 76–78. A B Mk IV, DK290 was initially used as a trials aircraft for the bomb, followed by DZ471,530 and 533.Sharp and Bowyer 1971, pp. 74–75. The B Mk IV had a maximum speed of 380 mph (610 km/h), a cruising speed of 265 mph (426 km/h), ceiling of 34,000 ft (10,000 m), a range of 2,040 nmi (3,780 km), and a climb rate of 2,500 ft per minute (762 m).Bowman 2005, p. 25.
Other bomber variants of the Mosquito included the Merlin 21 powered B Mk V high-altitude version. Trials with this configuration were made with W4057, which had strengthened wings and two additional fuel tanks, or alternatively, two 500 pounds (230 kg) bombs. This design was not produced in Britain, but formed the basic design of the Canadian-built B.VII. Only W4057 was built in prototype form.Jackson 2003, p. 16. The Merlin 31 powered B Mk VII was built by de Havilland Canada and first flown on 24 September 1942. It only saw service in Canada, 25 were built. Six were handed over to the United States Army Air Forces.
B Mk IX (54 built) was powered by the Merlin 72,73, 76 or 77. The two-stage Merlin variant was based on the PR.IX. The prototype DK 324 was converted from a PR.VIII and first flew on 24 March 1943.Jackson 2003, p. 17. In October 1943 it was decided that all B Mk IVs and all B Mk IXs then in service would be converted to carry the 4,000 pounds (1,800 kg) "Cookie", and all B Mk IXs built after that date were designed to allow them to be converted to carry the weapon.Sharp and Bowyer 1971, p. 306 The B Mk IX had a maximum speed of 408 mph (657 km/h), an economical cruise speed of 295 mph (475 km/h) at 20,000 ft, and 350 mph (560 km/h) at 30,000 ft, ceiling of 36,000 ft (11,000 m), a range of 2,450 nmi (4,540 km), and a climb rate of 2,850 feet per minute (869 m). The IX could carry a maximum load of 2,000–4,000 lb (910–1,810 kg) of bombs. A Mosquito B Mk IX holds the record for the most combat operations flown by an Allied bomber in the Second World War. LR503, known as "F for Freddie" (from its squadron code letters, GB*F), first served with No. 109 and subsequently, No. 105 RAF squadrons. It flew 213 sorties during the war, only to crash at Calgary airport during the Eighth Victory Loan Bond Drive on 10 May 1945, two days after Victory in Europe Day, killing both the pilot, Flt. Lt. Maurice Briggs, DSO, DFC, DFM and navigator Fl. Off. John Baker, DFC and Bar.Bowman 2005, p. 70.
The B Mk XVI was powered by the same variations as the B.IX. All B Mk XVIs were capable of being converted to carry the 4,000 pounds (1,800 kg) "Cookie". The two-stage powerplants were added along with a pressurised cabin. DZ540 first flew on 1 January 1944. The prototype was converted from a IV (402 built). The next variant, the B Mk XX, was powered by Packard Merlins 31 and 33s. It was the Canadian version of the IV. Altogether, 245 were built. The B Mk XVI had a maximum speed of 408 mph (657 km/h), an economical cruise speed of 295 mph (475 km/h) at 20,000 ft, and 350 mph (560 km/h) at 30,000 ft, ceiling of 37,000 ft (11,000 m), a range of 1,485 nmi (2,750 km), and a climb rate of 2,800 ft per minute (853 m). The type could carry 4,000 pounds (1,800 kg) of bombs.
The B.35 was powered by Merlin 113 and 114As. Some were converted to TT.35s (Target Tugs) and others were used as PR.35s (photo-reconnaissance). The B.35 had a maximum speed of 422 mph (679 km/h), a cruising speed of 276 mph (444 km/h), ceiling of 42,000 ft (13,000 m), a range of 1,750 nmi (3,240 km), and a climb rate of 2,700 ft per minute (823 m).Bowman 2005, p. 26. A total of 174 B.35s were delivered up to the end of 1945. [nb 20] A further 100 were delivered from 1946 for a grand total of 274, 65 of which were built by Airspeed Ltd.Bowman 2005, p. 166.
==Notes==
==Sources==
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