de Havilland
Mosquito
B MK IV
Bomber 
  FS2004 
  JRLucariny FSDS Model 
Jul/2010
De Havilland Mosquito
Great Britain
It is one of the paradoxes of aircraft development that some of the world's greatest aeroplanes have achieved their fame doing jobs other than the one for which they were originally designed.
No better example of this could be found than the Mosquito, which, conceived as a bomber, became one of the war's most potent fighters. More than this, indeed, it was probably the most successfully versatile of any twin-engined type built between 1939 and 1945.
It excelled in all the widely varied roles. Its duties included the duties of low-level and high-attack day and night bomber, long-range photo-reconnaissance, mine layer, pathfinder, high-speed military transport, long-range day and night fighter, and fighter-bomber.
It served in Europe, the Middle and Far east and on the Russian front. In fact, the ubiquitous Mosquito reigned supreme among General Purpose types. Of the grand total of 7,781 Mosquitos built, 6,710 were delivered during the war years.
On March 1, 1940, the first contract was placed, for fifty D.H.98 bombers (including prototypes) to be built to specification B.1/40 which had been written around De Havilland's proposals, and the name Mosquito was approved.
The period was an inauspicious one for the initiation of so radical a design. With the war going against Britain, the tendency was to concentrate on existing designs.
With the fall of France and the Dunkirk evacuation, the Mosquito was actually dropped from Ministry of Aircraft Production programs at one stage, setting back the ordering of materials.
But permission to proceed was later given again, although De Havillands were told that their Tiger Moth and Oxford production were to take priority. Had it not been that the Mosquito used "non-strategic" molded plywood for its construction, it might well never have been reinstated.
Construction of the prototype was pressed ahead through the difficult months of 1940. While the "Battle of Britain" was fought out overhead, bombs fell within a mile of the Hatfield factory, on one day in every five.
Nearly 25 per cent of the working hours, day and night, were spent in air-raid shelters. Despite all these vicissitudes, the prototype (W4050) made its first flight on November 25, 1940, only ten months and twenty-six days after detailed design work had commenced. The pilot was Geoffrey De Havilland, Jr. Meanwhile, inevitably, requirements had been changing.
There was some loss of confidence in the high-speed bomber, while the heavily armed long range fighter grew in favor.
The contract was therefore changed to twenty bombers and thirty fighters, necessitating the modification of a number of parts already manufactured.
Construction of a fighter prototype proceeded at Salisbury Hall, London Colney, which served as a dispersal for the Hatfield design office and experimental shop.
Two days before this prototype (W4052) was ready to fly, a German agent was dropped by parachute close to Salisbury Hall, in plain clothes and with a portable radio. He was captured next day, and the day after, May 15, 1941, Geoffrey De Havilland flew the fighter prototype from a 450-yard field beside the shed in which it had been built.
The first Mosquito sortie was made on September 20,1941, when a single aircraft made a reconnaissance flight over France.
At home, the Mosquito night fighter, carrying A.I Mk IV airborne radar, began to take over from the Bristol Blenheim.
It had been decided that an attack should be made on the German Gestapo headquarters in Oslo, Norway, which contained records of members of underground resistance organizations. Such a mission would, if successful, help protect those who were supplying Britain with secret information. Therefore, on September 25,1942, Mosquitos carried out a long range attack on the HQ, accurately bombing the building and then returning home at high speed.
The basic fighter Mosquito introduced into squadron service in 1942 was the N.F.Mk.II, equipped primarily as a night-fighter and used for home defense alongside the Bristol Beaufighter. Its armament comprised four 20 mm cannon in the front fuselage belly and four 0.303 in. Browning machine-guns in the extreme nose. It carried Aircraft Interception (AI) Mk.IV or AI Mk.V "arrowhead" radar and a G-45 machine gun. Its matt-black overall finish, incidentally, reduced its maximum speed by 16 mph. Power was provided either by two Merlin 21 engines giving 1,280 hp for takeoff and 1,480 hp at 12,250 feet, or two Merlin 23 engines giving 1,390 hp for takeoff and the same maximum power at 12,250 feet.
On the night of May 28-29,1942, Mosquito N.F.IIs scored their first "probable," and in the following three years, Mosquito night-fighters racked up a score of approximately 600 enemy aircraft over the British Isles, and also destroyed 600 flying bombs in a two month period. They later operated in the bomber support role, their task being to defend the main heavy bomber streams over enemy territory. Of the 466 Mark II Mosquito fighters produced, some of the later aircraft had day-fighter finish and, with the AI radar removed, operated over Malta, Italy, Sicily and North Africa from the end of 1942 onwards.
Operational experience with the Mosquito II in its day-fighter and intruder roles led to the development of the F.B.VI, a potent fighter-bomber which came into service during the early months of 1943.
It had been discovered that the Mosquito was able to accommodate a much greater warload than that for which it had been designed, and thus the Mark VI, with a strengthened wing for external loads which later became known as the "basic" wing, carried a full complement of cannon and machine-guns, two 500 lb. bombs in the rear half of the bomb bay (the front half containing the cannon breeches) and two 500 lb. bombs under the wings. Actually, the full 2,000 lb. bomb load was only carried by the Mark VI Series 2 which took advantage of the 1,620 hp available from the Merlin 25 for takeoff, the first 300 machines being F.B.VI Series 1 Mosquitos with Merlin 21s or 23s and carrying two 250 lb. bombs internally.
Later, in mid-1943, the Mosquito FB Mk VI was becoming operational. As well as the usual RAF duties, it was used by Coastal Command as an anti-shipping aircraft, armed with eight 60 lb. rocket projectiles. More unusual weapons carried by some Mosquitos included a 57 mm cannon for ground attack (this devastating gun was capable of destroying any armored vehicle), and the 4,000 lb. 'block-buster' bomb. Even with this bomb on board, the Mosquito could out fly most German night fighters, and on numerous occasions it attacked far-off Berlin and German V1 flying-bomb sites.
An entirely separate line of development from the Mosquito Night Fighter (NF) II produced a series of night-fighting variants which were primarily used for home-defense purposes. The first of these was the NF XII, plans to produce the NF VI with Merlin 21s and the "basic" wing, and the NF X with Merlin 61s and the "basic" wing, having been abandoned. The Mosquito NF XII became the first British aircraft to carry centimetric AI radar. This form of radar introduced the spinning-dish scanner with greatly improved performance compared with the earlier "arrow-head" type, but it resulted in some singularly unattractive nose contours on the aircraft in which it was carried. The centimetric radar supplanted the four machine guns in the fuselage nose, reducing the armament to four 20 mm Hispano cannon. To expedite its service debut, the Mosquito XII was based directly on the Mark II and ninety-seven machines were converted by the installation of the new radar.
Of the Mosquitos built in Canada, the F.B.26 was one of the chief variants, the design of which was based upon that of the F.B.VI. With the same armament as its British counterpart, it had Packard Merlin 225 engines and weighed 21,473 lbs. The sole F.B.24 was similar but had Packard Merlin 69s, while the F.B.21, of which only three were built, had Packard Merlin 31 or 33 engines. Australian production was also based initially on the fighter-bomber, the F.B.40 being similar to the F.B.VI but having Packard Merlin 31 (first hundred production machines) or 33 (last seventy-eight) engines. One F.B.40 was re-engined with Packard Merlin 69s and redesignated Mosquito F.B.42, but no production of this version was undertaken.
No fewer than twenty-seven different versions of the Mosquito went into service during the war years, and some of the most spectacular operations of the air war stood to its credit. The Mosquito carried phenomenal loads over extremely long distances, performing feats out of all proportion to the specification originally envisaged by its designers. In short, the Mosquito was an outstanding warplane on every count.
Mosquitos were active on D-Day, and right up to the end of the war. Others were license built in Canada and Australia. Production did not end in Britain until late 1950.
http://www.aviation-history.com/dehavilland/mosquito.html

De Havilland Mosquito B Mk IV:
Initial day and night bomber variant. Ten aircraft in initial production batch started as PR Mk I airframes but completed as bombers, known initially as PR/Bomber Conversion Type but redesignated B Mk IV Series 1 before service, including the bomber prototype first flown mid-September 1941, also considered as prototype for B Mk V. B Mk IV Srs Is had Merlin 21s, short nacelles and bomb load of 2,000 lb (908 kg) in two or four bombs.
Deliveries to No 105 Sqn began November 1941 but large-scale operations awaited arrival of B Mk IV Srs 2, the first example of which flew March 1942, this having long-tail nacelles, Merlin 21 or 23 engines and provision for 50-Imp gal (227-1) wing drop tanks.
First operation (four aircraft to Cologne) on May 31, 1942. Production of 300 B Mk IV Srs 2, less nine converted to other versions in production. Post-delivery modifications of 27 to PR Mk IV, with cameras as PR Mk I; 20 to carry one 4,000-lb (1,816-kg) bomb each in bulged bomb-bay, with gross weight of 21,500 lb (9,760 kg), commenced operations with Nos 627 and 692 Sqns February 23, 1944; 36 aircraft modified 1943 to carry Highball anti-ship-ping spinning bomb for operations with No 618 Sqn, 24 of these later having arrester gear, Merlin 25s and other mods for carrier-based operations in Pacific, but no operations undertaken.

Data for standard B Mk IV Srs 2:
Max speed, 380 mph (611 km/h). Cruising speed, 265 mph (426 km/h). Rate of climb., 2,500 ft/win (12.71 m/sec).
Ceiling, 34,000 ft (10,363 m). Max range, 2,040 mis (3,282 km). Empty weight, 13,400 lb (6,084 kg). Gross weight, 21,462 lb (9,744 kg).
http://www.airpages.ru/eng/uk/mos_4.shtml