De Havilland Mosquito The de Havilland DH . 98 Mosquito was a British multi - role combat aircraft with a two - man crew that served during the Second World War and the postwar era . The Mosquito was one of the few operational front - line aircraft of the World War II era to be constructed almost entirely of wood and , as such , was nicknamed " The Wooden Wonder " . The Mosquito was also known affectionately as the " Mossie " to its crews . Originally conceived as an unarmed fast bomber , the Mosquito was adapted to many other roles during the air war , including low - to medium - altitude daytime tactical bomber , high - altitude night bomber , pathfinder , day or night fighter , fighter - bomber , intruder , maritime strike aircraft , and fast photo - reconnaissance aircraft . It was also used by the British Overseas Airways Corporation ( BOAC ) as a transport . When the Mosquito entered production in 1941 , it was one of the fastest operational aircraft in the world . Entering widespread service in 1942 , the Mosquito first operated as a high - speed , high - altitude photo - reconnaissance aircraft , and continued to operate in this role throughout the war . From mid - 1942 to mid - 1943 Mosquito bombers were used in high - speed , medium - or low - altitude missions , attacking factories , railways and other pinpoint targets within Germany and German - occupied Europe . From late 1943 , Mosquito bomber units were formed into the Light Night Strike Force and used as pathfinders for RAF Bomber Command ' s heavy - bomber raids . They were also used as " nuisance " bombers , often dropping 4 , 000 lb ( 1 , 812 kg ) " cookies " , in high - altitude , high - speed raids that German night fighters were almost powerless to intercept . As a night fighter , from mid - 1942 , the Mosquito was used to intercept " Luftwaffe " raids on the United Kingdom , most notably defeating the German aerial offensive , " Operation Steinbock " , in 1944 . Offensively , starting in July 1942 , some Mosquito night - fighter units conducted intruder raids over " Luftwaffe " airfields and , as part of 100 Group , the Mosquito was used as a night fighter and intruder in support of RAF Bomber Command ' s heavy bombers , and played an important role in reducing bomber losses during 1944 and 1945 . As a fighter - bomber in the Second Tactical Air Force , the Mosquito took part in " special raids " , such as the attack on Amiens Prison in early 1944 , and in other precision attacks against Gestapo or German intelligence and security forces . Second Tactical Air Force Mosquitos also played an important role operating in tactical support of the British Army during the 1944 Normandy Campaign . From 1943 Mosquitos were used by RAF Coastal Command strike squadrons , attacking " Kriegsmarine " U - boat s ( particularly in the 1943 Bay of Biscay offensive , where significant numbers of U - boats were sunk or damaged ) and intercepting transport ship concentrations . The Mosquito saw service with the Royal Air Force ( RAF ) and many other air forces in the European theatre , and the Mediterranean and Italian theatres . The Mosquito was also used by the RAF in the South East Asian theatre , and by the Royal Australian Air Force ( RAAF ) based in the Halmaheras and Borneo during the Pacific War . Development . By the early - mid - 1930s , de Havilland established a reputation for innovative high - speed aircraft with the DH . 88 Comet racer , while the later DH . 91 Albatross airliner successfully pioneered the composite wood construction that the Mosquito would use . The 22 - passenger Albatross could cruise at at , a vast improvement on the Handley Page H . P . 42 and other biplanes it was replacing . 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 simplified production and reduced construction time . 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 for with a maximum speed of at ; a maximum bomb load of which could be carried over shorter ranges was also specified . Major 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 . In May 1937 , as a comparison to P . 13 / 36 , George Volkert , who was the chief designer of Handley Page , put forward to the Air Ministry the concept of a fast unarmed bomber . In his 20 - page document , Volkert laid out plans for an aerodynamically clean medium bomber that would carry of bombs at a cruising speed of . There was some support for the idea in the RAF and Air Ministry ; for example Captain R N Liptrot , who was then Research Director Aircraft 3 ( RDA3 ) , appraised Volkert ' s design , calculating that its top speed would exceed that of the brand new Supermarine Spitfire . There were , however , counter - arguments that , although such a design had merit , it would not necessarily maintain a speed advantage over enemy fighters for long . The Ministry was also considering the use of non - strategic material s for aircraft production , which , in 1938 , led to specification B . 9 / 38 and the development of the Albemarle medium bomber , which was largely constructed from spruce and plywood attached to a steel - tube frame . Thus it can be seen that the idea of a small , fast bomber , possibly made out of non - strategic materials , was already gaining support at a much earlier stage than is sometimes acknowledged . Inception of the de Havilland fast bomber . Geoffrey de Havilland also believed that for a bomber , an aerodynamically clean design , with minimal skin area , was a better concept than the P . 13 / 36 specification . He initially thought that adapting the Albatross airliner to meet the RAF ' s requirements was a time - saving possibility . In April 1938 , performance estimates were produced of a twin Rolls - Royce Merlin powered DH . 91 , with the Bristol Hercules and Napier Sabre as alternatives . On 7 July 1938 , Geoffrey de Havilland sent a letter to Air Marshal Wilfred Freeman , the Air Council ' s member for Research and Development , discussing the specification and arguing that in the event of war , there would be shortages of materials such as duralumin or steel , while there should be plentiful supplies of wood . Additionally , although inferior torsionally , the strength to weight ratio of wood was as good as that of duralumin or steel , and , given such considerations , a different approach to designing a high - speed bomber was possible . After further consideration , in a follow - up letter sent to Freeman on 27 July , de Havilland stated that the P . 13 / 36 specification could not be met by a twin Merlin powered aircraft and that either the top speed or load carrying capacity would be compromised , depending on which was paramount . For example , a larger , slower , turret armed aircraft would have a range of carrying a bomb load , with a maximum speed of at , and a cruising speed of at . De Havilland believed that such a concept was too much of a compromise , and that getting rid of some surplus equipment would lead to a better design . On 4 October 1938 , for example , de Havilland projected the performance of another design based on the D . H . 91 Albatross , powered by two Merlin Xs , with a three - man crew and armed with six or eight forward firing guns , plus one or two manually operated guns and a tail turret . Based on a total loaded weight of it would have a top speed of and cruising speed of at . Still believing that this performance could be improved upon , and after examining more concepts based on the Albatross and the new all - metal DH . 95 Flamingo , de Havilland settled on designing a completely new aircraft that would be aerodynamically clean , of wooden construction and powered by the Merlin , which offered promise of substantial future development . The new design would be faster than all current or foreseeable enemy fighter aircraft , and could dispense with a defensive armament , which would only slow it down and make interception or losses to anti - aircraft guns more likely . Instead , high speed and good manoeuvrability would make it easier for the design to evade both fighters and ground fire . Also , the lack of turrets meant that production would be simplified and production time reduced , with a delivery rate far in advance of any competing designs . Without armament , the crew could be reduced to a pilot and a navigator . This was in contrast to contemporary RAF design philosophy , which required well - armed heavy bombers and was much more akin to the German " schnellbomber " concept . During a meeting held in early October 1938 between Geoffrey de Havilland , Charles C Walker ( de Havilland ' s chief engineer ) and Air Ministry officials , the latter showed little interest in de Havilland ' s concept and , instead , asked de Havilland to build wings for other bombers as a sub - contractor . By September 1939 de Havilland had produced preliminary estimates for both single - and twin - engined variations of light - bomber designs using different engines , while speculating on the effects of defensive armament on their designs . One design , completed on 6 September , was for an aircraft powered by a single Napier Sabre , with a wingspan of and capable of carrying a bomb load . On 20 September , in another letter to Wilfred Freeman , Geoffrey de Havilland wrote " . . . we believe that we could produce a twin - engine bomber which would have a performance so outstanding that little defensive equipment would be needed . " By 4 October work had progressed to a twin engine light bomber with a wingspan of , and powered by either Merlin or Griffon engines , with the Merlin being favoured because of its immediate availability . On 5 October 1939 , with the Second World War a month old , the nucleus of a design team under the leadership of Eric Bishop , de Havilland ' s chief designer , moved to the security and secrecy of Salisbury Hall and started work on what was now known as the DH . 98 . With an eye to making the DH . 98 more versatile , Bishop made provision for four 20 mm cannon which could be installed in the forward half of the bomb bay , immediately under the cockpit , and firing via blast tubes and troughs under the forward fuselage . The DH . 98 was still too radical for the Air Ministry , which still wanted a heavily armed , multi - role aircraft , combining medium bomber , reconnaissance and " general purpose " roles , as well as being capable of maritime strike , for which torpedo carrying equipment was specified . With the outbreak of the war , the Air Ministry became more receptive , but were still sceptical about sanctioning an unarmed bomber and thought that the Germans would produce fighters which were faster than expected . Instead , the Ministry asked de Havilland to compromise and suggested two forward and two rear firing machine guns for defence . The Air Ministry also opposed a two - man bomber , wanting at the very least a third crewman to reduce the workload of the others on long flights . The Air Council then added further requirements , such as remotely controlled guns , a top speed of at on two - thirds engine power , and a range of with a bomb load . To appease the Air Ministry , de Havilland built several mock - ups with a gun turret just aft of the cockpit , but , apart from this compromise , de Havilland made no changes to the fundamentals of the design . On 12 November , at a meeting considering fast bomber ideas put forward by de Havilland , Blackburn , and Bristol , Marshal W . Freeman directed de Havilland to produce a fast aircraft , powered initially by Merlin engines , with options of using progressively more powerful engines , including the Rolls - Royce Griffon and the Napier Sabre . Although estimates for a slightly larger Griffon powered aircraft , armed with a four - gun tail turret , were presented , Freeman was able to get the requirement for defensive weapons dropped , and a draft requirement was raised calling for a high - speed light reconnaissance bomber capable of at . One month later , on 12 December 1939 , the Vice - Chief of the Air Staff , Director General of Research and Development , Air Officer Commanding - in - Chief ( AOC - in - C ) of RAF Bomber Command met to finalise the details of the design and decide how it was to fit within the RAF ' s strategic aims . The AOC - in - C still would not accept an unarmed bomber , but insisted it would be suitable for reconnaissance missions with either F8 or F24 camera s . After representatives of the company , the Air Ministry and the RAF ' s operational commands had examined a full scale mock - up at Hatfield on 29 December 1939 , the project finally received official backing . This was confirmed on 1 January 1940 , when Air Marshal Freeman chaired another meeting with Geoffrey de Havilland , John Buchanan , ( Deputy of Aircraft Production ) and John Connolly , who was Buchanan ' s chief of staff . Claiming the DH . 98 was the " fastest bomber in the world " , de Havilland added " it must be useful " . Freeman supported its production for RAF service and ordered a single prototype for an unarmed bomber variant to specification B . 1 / 40 / dh , which called for a light bomber / reconnaissance aircraft powered by two Rolls - Royce RM3SM ( experimental designation for what became known as the Merlin 21 ) with ducted radiators , capable of carrying a bomb load . The aircraft was to have a speed of at and a cruising speed of at with a range of at on full tanks . Maximum service ceiling was to be . On 1 March 1940 , Air Marshal Roderic Hill issued a contract under Specification B . 1 / 40 , for 50 bomber - reconnaissance variants of the DH . 98 : this contract included the prototype , which was given the factory serial " E0234 " . In May 1940 , specification F . 21 / 40 was issued , calling for a long - range fighter armed with four 20 mm cannon and four . 303 machine guns in the nose , after which de Havilland were authorised to build a prototype of a fighter version of the DH . 98 . It was decided after some debate , that this prototype , given the serial number " W4052 " , would carry Airborne Interception ( AI ) Mk . IV equipment as a day and night fighter . By June 1940 , the DH . 98 had been given the name " Mosquito " . Having the fighter variant helped keep the Mosquito project alive because there was still plenty of criticism over the usefulness of an unarmed bomber within the government and Air Ministry , even after the first prototype had flown and shown its capabilities . Project Mosquito . Once the design of the DH . 98 had started , de Havilland built several mock - ups , the most detailed of which was at Salisbury Hall , in the hangar where " E0234 " was being built . Initially , this mock - up was designed with the crew completely enclosed in the fuselage behind a completely transparent nose ( similar to that of the Bristol Blenheim or Heinkel He 111 H ) , but this was quickly altered to a more solid nose with a more conventional canopy . The construction of the prototype began in March 1940 , but work was cancelled again after the Battle of Dunkirk , when Lord Beaverbrook , as Minister of Aircraft Production decided there was no production capacity for aircraft like the DH . 98 , which was not expected to be in service until early 1941 . Although Lord Beaverbrook told Air Vice - Marshal Freeman that work on the project had better stop , he did not issue a specific instruction , and Freeman ignored the request . In June 1940 , however , Lord Beaverbrook and the Air Staff ordered that production was to focus on five existing types , namely the Supermarine Spitfire , Hawker Hurricane , Vickers Wellington , Armstrong - Whitworth Whitley and the Bristol Blenheim . Work on the DH . 98 prototype stopped , and it seemed that the project would be shut down when the design team were denied the materials with which to build their prototype . The Mosquito was only reinstated as a priority in July 1940 , after de Havilland ' s General Manager L . C . L Murray , promised Lord Beaverbrook 50 Mosquitoes by December 1941 , and this , only after Beaverbrook was satisfied that Mosquito production would not hinder de Havilland ' s primary work of producing Tiger Moth and Oxford trainers and repairing Hurricanes as well as the licence manufacture of Merlin engines . In promising Beaverbrook 50 Mosquitoes by the end of 1941 , de Havilland was taking a gamble , because it was unlikely that 50 Mosquitos could be built in such a limited time ; as it transpired only 20 Mosquitos were built in 1941 , but the other 30 were delivered by mid - March 1942 . During the Battle of Britain , nearly a third of de Havilland ' s factory time was lost because the workers took cover in the factory ' s bomb shelters . Nevertheless , work on the prototype went quickly , such that " E0234 " was rolled out on 19 November 1940 . In the aftermath of the Battle of Britain , the original order was changed to 20 bomber variants and 30 fighters . It was still uncertain whether the fighter version should have dual or single controls , or should carry a turret , so three prototypes were eventually built : " W4052 " , " W4053 " and " W4073 " . The latter , both turret armed , were later disarmed , to become the prototypes for the T . III trainer . This caused some delays as half - built wing components had to be strengthened for the expected higher combat load requirements . The nose sections also had to be altered , omitting the clear perspex bomb - aimer ' s position , to solid noses designed to house four . 303 machine guns and their ammunition . Prototypes and test flights . On 3 November 1940 , the aircraft , still coded " E0234 " , was transported by road to Hatfield , and placed in a small blast - proof assembly building , where successful engine runs were made on 19 November . Two Merlin 21 two - speed single - stage supercharged engines were installed driving three - bladed de Havilland Hydromatic constant - speed , controllable - pitch propellers . " E0234 " had a wingspan of and was the only Mosquito to be built with Handley Page slats on the outer leading edges of the wings . Test flights showed that these were not needed and they were disconnected and faired over with doped fabric ( these slats can still be seen on " W4050 " ) . On 24 November 1940 , taxiing trials were carried out by Geoffrey de Havilland , Jr . , who was the company ' s chief test pilot and responsible for maiden flights . The tests were successful and the prototype was subsequently readied for flight testing , making its first flight piloted by Geoffrey de Havilland , on 25 November . The flight was made 11 months after the start of detailed design work , a remarkable achievement considering the conditions of the time . For this maiden flight , " E0234 " , weighing , took off from a field beside the shed it was built in . John E . Walker , Chief Engine Installation designer , accompanied de Havilland . The takeoff was " straight forward and easy " and the undercarriage was not retracted until a considerable height was obtained . The aircraft reached , with the only problem being the undercarriage doors - which were operated by bungee cord s attached to the main undercarriage legs - that remained open by some at that speed . This problem persisted for some time . The left wing of " E0234 " also had a tendency to drag to port slightly , so a rigging adjustment was carried out before further flights . On 5 December 1940 , the prototype experienced tail buffeting at speeds between and . The pilot noticed this most in the control column , with handling becoming more difficult . During testing on 10 December , wool tufts were attached to the suspect areas to investigate the direction of airflow . The conclusion was that the airflow separating from rear section of the inner engine nacelles was disturbed , leading to a localised stall and the disturbed airflow was striking the tailplane , causing the buffeting . In an attempt to smooth the air flow and deflect it from striking the tailplane with such force , the company experimented with non - retractable slots , fitted to the inner engine nacelles and to the leading edge of the tailplane . These slots , and wing root fairings fitted to the forward fuselage and leading edge of the radiator intakes , stopped some of the vibration experienced by the pilot but failed to cure the tailplane buffeting . In February 1941 , the buffeting was eliminated by incorporating triangular fillets on the trailing edge of the wings and lengthening the nacelles , the trailing edge of which curved up to fair into the fillet some behind the wing ' s trailing edge : this meant the flaps had to be divided into inboard and outboard sections . By January 1941 , the prototype was carrying the military serial number " W4050 " . With the buffeting problems largely resolved , John Cunningham flew " W4050 " on 9 February 1941 . He was greatly impressed by the " lightness of the controls and generally pleasant handling characteristics " . Cunningham concluded that when the type was fitted with AI equipment , it would be a perfect replacement for the Bristol Beaufighter . During its trials on 16 January 1941 , " W4050 " outpaced a Spitfire at . The original estimates were that as the Mosquito prototype had twice the surface area and over twice the weight of the Spitfire Mk II , but also with twice its power , the Mosquito would end up being faster . Over the next few months , " W4050 " surpassed this estimate , easily beating the Spitfire Mk II in testing at RAF Boscombe Down in February 1941 , reaching a top speed of at altitude , compared to a top speed of at for the Spitfire . On 19 February , official trials began at the Aeroplane and Armament Experimental Establishment ( A & AEE ) based at Boscombe Down , although de Havilland ' s representative was surprised by a delay in starting the tests . On 24 February , as " W4050 " taxied across the rough airfield , the tailwheel jammed leading to the fuselage fracturing : this was replaced by the fuselage of the Photo - Reconnaissance prototype " W4051 " in early March . In spite of this setback , the " Initial Handling Report 767 " issued by the A & AEE stated " The aeroplane is pleasant to fly . . . Aileron control light and effective . . . " The maximum speed reached was at , with an estimated maximum ceiling of and a maximum rate of climb of at . " W4050 " continued to be used for long and varied testing programs , being essentially the experimental " workhorse " for the Mosquito family . In late October 1941 , it was taken back to the factory to be fitted with Merlin 61s , the first production Merlins fitted with a two - speed , two - stage supercharger . The first flight with the new engines was on 20 June 1942 . " W4050 " recorded a maximum speed of at ( fitted with straight - through air intakes with snowguards , engines in F . S . gear ) and at without snowguards . In October 1942 , in connection with development work on the NF Mk XV , " W4050 " was fitted with extended wingtips increasing the span to , first flying in this configuration on 8 December . Finally , fitted with high - altitude rated two - stage , two - speed Merlin 77s , it reached in December 1943 . Soon after these flights , " W4050 " was grounded and was scheduled to be scrapped , but instead continued to serve as an instructional airframe at Hatfield . In September 1958 , " W4050 " was returned to the Salisbury Hall hangar in which it had been built , was restored to its original configuration and is now one of the primary exhibits of the de Havilland Aircraft Heritage Centre . " W4051 " , which was designed from the outset to be the prototype for the photo - reconnaissance versions of the Mosquito , was slated to make its first flight in early 1941 . However , the fuselage fracture in " W4050 " meant that " W4051 ' s " fuselage was used as a replacement ; " W4051 " was then rebuilt using a production standard fuselage and first flew on 10 June 1941 . This prototype continued to use the short engine nacelles , single - piece trailing edge flaps and the " No . 1 " tailplane used by " W4050 " , but had production standard wings and , thus configured , became the only Mosquito prototype to fly operationally . Construction of the fighter prototype , " W4052 " was also carried out at the secret Salisbury Hall facility . The new prototype differed from its bomber brethren in a number of ways . It was powered by Merlin 21s and had an altered canopy structure with a flat bullet - proof windscreen . Four 20 mm ( . 79 in ) Hispano Mk II cannon were housed in a compartment under the cockpit floor , with the breeches projecting into the bomb bay . The bomb bay doors were replaced by manually operated bay doors which incorporated cartridge ejector chutes . The solid nose mounted four . 303 in ( 7 . 7 mm ) Browning machine guns and their ammunition boxes which were accessed by a single large , sideways hinged panel . In accordance with its role as a day / night fighter prototype " W4052 " was equipped with AI Mk . IV equipment , complete with an " arrowhead " - shaped transmission aerial mounted between the central Brownings , and receiving aerials through each outer wingtip , and it was painted in overall black RDM2a " Special Night " finish . It was also the first prototype constructed with the extended engine nacelles . " W4052 " was later tested with other modifications including bomb racks , drop tanks , barrage balloon cable cutters in the leading edge of the wings , Hamilton airscrews and braking propellers , as well as drooping aileron systems which enabled steep approaches , and a larger rudder tab . The prototype continued to serve as a test machine until it was scrapped on 28 January 1946 . " W4055 " flew the first operational Mosquito flight on 17 September 1941 . During flight testing , the Mosquito prototypes were modified to test a number of experimental configurations . " W4050 " was fitted with a turret behind the cockpit for drag tests , after which the idea was abandoned in July 1941 . " W4052 " had the first version of the Youngman Frill airbrake fitted to the fighter prototype . The frill was opened by bellows and venturi effect to provide rapid deceleration during interceptions and was tested between January - August 1942 , but was also abandoned when it was discovered that lowering the undercarriage had the same effect with less buffeting . Early on in the Mosquito ' s operational life , the cooling intake shrouds that were to cool the exhausts on production aircraft overheated after a while . Flame dampers prevented exhaust glow on night operations , but they had an effect on performance . Multiple ejector and open - ended exhaust stubs helped solve the problem and were used in the PR . VIII , B . IX and B . XVI variants . This increased speed performance in the B . IX alone by per hour . Production plans and American interest . The Air Ministry had authorised mass production plans to be drawn up on 21 June 1941 , by which time the Mosquito had become one of the world ' s fastest operational aircraft . The Air Ministry ordered 19 photo - reconnaissance ( PR ) models and 176 fighters . A further 50 were unspecified ; in July 1941 , the Air Ministry confirmed these would be unarmed fast bombers . By the end of January 1942 , contracts had been awarded for 1 , 378 Mosquitos of all variants , including 20 T . III trainers and 334 FB . VI bombers . Another 400 were to be built by de Havilland Canada . On 20 April 1941 , " W4050 " was demonstrated to Lord Beaverbrook , the Minister of Aircraft Production . The Mosquito made a series of flights , including one rolling climb on one engine . Also present were US General Henry H . Arnold and his aide Major Elwood Quesada , who wrote " I . . . recall the first time I saw the Mosquito as being impressed by its performance , which we were aware of . We were impressed by the appearance of the airplane that looks fast usually is fast , and the Mosquito was , by the standards of the time , an extremely well streamlined airplane , and it was highly regarded , highly respected . " The trials set up future production plans between Britain , Australia and Canada . The Americans did not pursue their interest . It was thought the Lockheed P - 38 Lightning could handle the same duties just as easily . Arnold felt the design was being overlooked , and urged the strategic personalities in the United States Army Air Forces to learn from the design if they chose not to adopt it . Several days after the attack on Pearl Harbor , the USAAF then requested one airframe to evaluate on 12 December 1941 , signifying that the USAAF realised that they had entered the war without a fast dual - purpose reconnaissance aircraft . Design . Overview . The Mosquito was a fast , twin - engined aircraft with shoulder - mounted wings . The most produced variant , designated the FB Mk VI ( Fighter - bomber Mark 6 ) , was powered by two Merlin Mk 23 or Mk 25 engines driving three - bladed de Havilland hydromatic propellers . The typical fixed armament for an FB Mk VI was four Browning . 303 machine guns and four 20 mm Hispano cannon while the offensive load consisted of up to of bombs , or eight RP - 3 unguided rockets . Construction . The oval - section fuselage was a frameless monocoque shell built in two halves being formed to shape by band clamp s over a mahogany or concrete mould , each holding one half of the fuselage , split vertically . The shell halves were made of sheets of Ecuadorean balsa wood sandwiched between sheets of Canadian birch , but in areas needing extra strength — such as along cut - outs — stronger woods replaced the balsa filler ; the overall thickness of the birch and balsa sandwich skin was only . This sandwich skin was so stiff that no internal reinforcement was necessary from the wing ' s rear spar to the tail bearing bulkhead . The join was along the vertical centre line . This split construction greatly aided the assembly of the internal equipment as it allowed the technicians easy access to the fuselage interior . While the glue in the plywood skin dried , carpenters cut a sawtooth joint into the edges of the fuselage shells , while other workers installed the controls and cabling on the inside wall . When the glue completely dried , the two halves were glued and screwed together . The fuselage was strengthened internally by seven bulkheads made up of two plywood skins parted by spruce blocks , which formed the basis on each half for the outer shell . Each bulkhead was a repeat of the spruce design for the fuselage halves ; a balsa sheet sandwich between two plywood sheets / skins . Bulkhead number seven carried the fittings and loads for the tailplane and rudder , The type of glue originally used was Casein , which was later replaced by " Aerolite " , a synthetic urea - formaldehyde , which was more durable . Many other types of screws and flanges ( made of various woods ) also held the structure together . The fuselage construction joints were made from balsa wood and plywood strips with the spruce multi - ply being connected by a balsa V joint , along with the interior frame . The spruce would be reinforced by plywood strips at the point where the two halves joined to form the V - joint . Located on top of the joint the plywood formed the outer skin . During the joining of the two halves ( " boxing up " ) , two laminated wooden clamps would be used in the after portion of the fuselage to act as support . A covering of doped Madapolam ( a fine plain woven cotton ) fabric was stretched tightly over the shell and a coat of silver dope was applied , after which the exterior camouflage was applied . The fuselage had a large ventral section cut - out , which was braced during construction , to allow it to be lowered onto the wing centre - section . Once the wing was secured the lower panels were replaced , and the bomb bay or armament doors fitted . The all - wood wing was built as a one - piece structure and was not divided into separate construction sections . It was made up of two main spars , spruce and plywood compression ribs , stringers , and a plywood covering . The outer plywood skin was covered and doped like the fuselage . The wing was installed into the roots by means of four large attachment points . The engine radiators were fitted in the inner wing , just outboard of the fuselage on either side . These gave less drag . The radiators themselves were split into three sections : an oil cooler section outboard , the middle section forming the coolant radiator and the inboard section serving the cabin heater . The wing contained metal framed and skinned ailerons , but the flaps were made of wood and were hydraulically controlled . The nacelles were mostly wood , although , for strength , the engine mounts were all metal as were the undercarriage parts . Engine mounts of welded steel tube were added , along with simple landing gear oleos filled with rubber blocks . Wood was used to carry only in - plane loads , with metal fittings used for all triaxially loaded components such as landing gear , engine mounts , control surface mounting brackets , and the wing - to - fuselage junction . The outer leading wing edge had to be brought further forward to accommodate this design . The main tail unit was all wood built . The control surfaces , the rudder and elevator were aluminium framed and fabric covered . The total weight of metal castings and forgings used in the aircraft was only . In November 1944 , several crashes occurred in the Far East . At first , it was thought these were as a result of wing structure failures . The casein glue , it was said , cracked when exposed to extreme heat and / or monsoon conditions . This caused the upper surfaces to " lift " from the main spar . An investigating team led by Major Hereward de Havilland travelled to India and produced a report in early December 1944 stating that " " the accidents were not caused by the deterioration of the glue but by shrinkage of the airframe during the wet monsoon season " . " However a later inquiry by Cabot & Myers definitely attributed the accidents to faulty manufacture and this was confirmed by a further investigation team by the Ministry of Aircraft Production at Defford which found faults in six different Marks of Mosquito ( all built at de Havilland ' s Hatfield and Leavesden plants ) which showed similar defects , and none of the aircraft had been exposed to monsoon conditions or termite attack ; thus it was concluded that there were construction defects found at the two plants . It was found that the " " Standard of glueing . . . left much to be desired " ” . Records at the time showed that accidents caused by " loss of control " were three times more frequent on Mosquitoes that on any other type of aircraft . The Air Ministry forestalled any loss of confidence in the Mosquito by holding to Major de Havilland ' s initial investigation in India that the accidents were caused " largely by climate " To solve the problem , a sheet of plywood was set along the span of the wing to seal the entire length of the skin joint along the main spar . Systems . The fuel systems allowed the Mosquito to have a good range and endurance , using up to nine fuel tanks . Two outer wing tanks each contained of fuel . These were complemented by two inner wing fuel tanks , each containing , located between the wing root and engine nacelle . In the central fuselage were twin fuel tanks mounted between bulkhead number two and three aft of the cockpit . In the FB . VI , these tanks contained each , while in the B . IV and other unarmed Mosquitos each of the two centre tanks contained . Both the inner wing , and fuselage tanks are listed as the " main tanks " and the total internal fuel load of was initially deemed appropriate for the type . In addition , the FB Mk VI could have larger fuselage tanks , increasing the capacity to . Drop tanks of or could be mounted under each wing , increasing the total fuel load to . In order to reduce fuel vaporisation at the high altitudes at which the photographic reconnaissance variants flew , the central and inner wing tanks were pressurised . The pressure venting cock located behind the pilot ' s seat controlled the pressure valve ; as the altitude increased , the valve increased the volume applied by a pump . This system was extended to include field modifications of the fuel tank system . The engine oil tanks were in the engine nacelles . Each nacelle contained a oil tank , including a air space . The oil tanks themselves had no separate coolant controlling systems . The coolant header tank was in the forward nacelle , behind the propeller . The remaining coolant systems were controlled by the coolant radiators shutters in the forward inner wing compartment , between the nacelle and the fuselage and behind the main engine cooling radiators which were fitted in the leading edge . Electric - pneumatic operated radiator shutters directed and controlled airflow through the ducts and into the coolant valves , to predetermined temperatures . Electrical power came from a 24 volt DC generator on the starboard ( No . 2 ) engine and an alternator on the port engine which supplied AC power for radios . The radio shutters , superchargers , gun camera , bomb bay , bomb / rocket release and all the other crew controlled instruments were powered by a 24 volt battery . The radio communication devices included VHF and HF communications , GEE navigation , and IFF and G . P . devices . The electric generators also powered the fire extinguishers . Located on the starboard side of the cockpit , the switches would operate automatically in the event of a crash . In flight , a warning light would flash to indicate a fire , should the pilot not already be aware of it . In later models , to save liquids and engine clean up time in case of belly landing , the fire extinguisher was changed to semi - automatic triggers . The design of the Mark VI allowed for a provisional long - range fuel tank to increase range for action over enemy territory , for the installation of bomb release equipment specific for depth charge s for strikes against enemy shipping , or for the simultaneous use of rocket projectiles along with a drop tank under each wing supplementing the main fuel cells . The FB . VI had a wingspan of , a length ( over guns ) of . It had a maximum speed of at . Maximum take - off weight was and the range of the aircraft was with a service ceiling of . The main landing gear were housed in the nacelles behind the engines . These were raised and lowered hydraulically . The main landing gear shock absorbers were de Havilland manufactured and used a system of rubber in compression , rather than hydraulic oleos , with twin pneumatic brakes for each wheel . The Dunlop - Marstrand anti - shimmy tailwheel was retractable . Flight characteristics . The design was noted for having light and effective control surfaces which allowed for good manoeuvrability . It was noted that the rudder should not be used aggressively at high speeds , and the poor aileron control at low speeds when landing and taking off was also a problem for inexperienced crews . For flying at low speeds , the flaps had to be set at 15° , speed reduced to and rpm set to 2 , 650 . The speed could be reduced to an acceptable for low speed flying . For cruising the maximum speed for obtaining maximum range was at weight . The Mosquito had a low stall speed of with undercarriage and flaps raised . When both were lowered , the stall speed decreased to . Stall speed at normal approach angle and conditions was . Warning of the stall was given by buffeting and would occur before stall was reached . The conditions and impact of the stall were not severe . The wing did not drop unless the control column was pulled back . The nose drooped gently and recovery was easy . Variants . Until the end of 1942 the RAF always used Roman numerals ( I , II , . . . ) for mark numbers ; 1943 - 1948 was a transition period during which new aircraft entering service were given Arabic numeral s ( 1 , 2 , . . . ) for mark numbers , but older aircraft retained their Roman numerals . From 1948 onwards , Arabic numerals were used exclusively . Prototypes . Three prototypes were built , each with a different configuration . The first to fly was " W4050 " on 25 November 1940 , followed by the fighter " W4052 " on 15 May 1941 and the photo - reconnaissance prototype " W4051 " on 10 June 1941 . " W4051 " later flew operationally with 1 Photographic Reconnaissance Unit ( 1 PRU ) . Photo - reconnaissance . A total of 10 Mosquito PR Mk Is were built , four of them " long range " versions equipped with a overload fuel tank in the fuselage . The contract called for 10 of the PR Mk I airframes to be converted to B Mk IV Series 1s . All of the PR Mk Is , and the B Mk IV Series 1s , had the original short engine nacelles and short span ( 19 ft 5 . 5 in ) tailplanes . Their engine cowlings incorporated the original pattern of integrated exhaust manifolds which , after a relatively brief flight time , had a troublesome habit of burning and blistering the cowling panels . The first operational sortie by a Mosquito was made by a PR Mk I , W4055 , on 17 September 1941 ; during this sortie the unarmed Mosquito PR . I evaded three Messerschmitt Bf 109 s at . Powered by two Merlin 21s , the PR Mk I had a maximum speed of , a cruise speed of , a ceiling of , a range of , and a climb rate of per minute . Over 30 Mosquito B Mk IV bombers were converted into the PR Mk IV photo - reconnaissance aircraft . The first operational flight by a PR Mk IV was made by " DK284 " in April 1942 . The Mosquito PR Mk VIII , built as a stopgap pending the introduction of the refined PR Mk IX , was the next photo - reconnaissance version . The five VIIIs were converted from B Mk IVs and became the first operational Mosquito version to be powered by two - stage , two - speed supercharged engines , using Rolls - Royce Merlin 61 engines in place of Merlin 21 / 22s . The first PR Mk VIII , " DK324 " first flew on 20 October 1942 . The PR Mk VIII had a maximum speed of , an economical cruise speed of at 20 , 000 ft , and at 30 , 000 ft , a ceiling of , a range of , and a climb rate of 2 , 500 ft per minute ( 760 m ) . The Mosquito PR Mk IX , 90 of which were built , was the first Mosquito variant with two - stage , two - speed engines to be produced in quantity ; the first of these , " LR405 " , first flew in April 1943 . The PR Mk IX was based on the Mosquito B Mk IX bomber and was powered by two Merlin 72 / 73 or 76 / 77 engines . It could carry either two , two or two droppable fuel tanks . The Mosquito PR Mk XVI had a pressurised cockpit and , like the Mk IX , was powered by two Rolls - Royce Merlin 72 / 73 or 76 / 77 piston engines . This version was equipped with three overload fuel tanks , totalling in the bomb bay , and could also carry two or drop tanks . A total of 435 of the PR Mk XVI were built . The PR Mk XVI had a maximum speed of , a cruise speed of , ceiling of , a range of , and a climb rate of 2 , 900 feet per minute ( 884 m ) . The Mosquito PR Mk 32 was a long - range , high - altitude , pressurised photo - reconnaissance version . It was powered by a pair of two - stage supercharged Rolls - Royce Merlin 113 and Merlin 114 piston engines , the Merlin 113 on the starboard side and the Merlin 114 on the port . First flown in August 1944 , only five were built and all were conversions from PR . XVIs . The Mosquito PR Mk 34 and PR Mk 34A was a very long - range unarmed high altitude photo - reconnaissance version . The fuel tank and cockpit protection armour were removed . Additional fuel was carried in a bulged bomb bay : 1 , 192 gallons which was the equivalent of . A further two 200 - gallon ( 910 - litre ) drop tanks under the outer wings gave a range of cruising at . Powered by two Merlin 114s first used in the PR . 32 . The port Merlin 114 drove a Marshal cabin supercharger . A total of 181 were built , including 50 built by Percival Aircraft Company at Luton . The PR . 34 ' s maximum speed ( TAS ) was at sea level , at and at . All PR . 34s were installed with four split F52 vertical cameras , two forward , two aft of the fuselage tank and one F24 oblique camera . Sometimes a K - 17 camera was used for air surveys . In August 1945 , the PR . 34A was the final photo - reconnaissance variant with one Merlin 113A and 114A each delivering . Colonel Roy M . Stanley II , USAF ( RET ) wrote : " I consider the Mosquito the best photo - reconnaissance aircraft of the war " . After the end of World War II Spartan Air Services used ten ex - RAF Mosquitoes , mostly B . 35 ' s plus one of only six PR . 35 ' s built , for high - altitude photographic survey work in Canada . Bombers . On 21 June 1941 the Air Ministry ordered that the last 10 Mosquitoes , 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 . 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 . Series 2 bombers also differed from the Series 1 in having a larger bomb bay to increase the payload to four bombs , instead of the four bombs of Series 1 . This was made possible by shortening the tail of the bomb so that these four larger 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 , 812 kg ) , thin - cased high explosive bomb ( nicknamed " Cookie " ) . The conversion , including modified bomb bay suspension arrangements , bulged bomb bay doors and fairings , was relatively straightforward , and 54 B . IVs were subsequently modified and distributed to squadrons of RAF Bomber Command ' s Light Night Striking Force . 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 . A B Mk IV , " DK290 " was initially used as a trials aircraft for the bomb , followed by " DZ471 , 530 and 533 " . The B Mk IV had a maximum speed of , a cruising speed of , ceiling of , a range of , and a climb rate of 2 , 500 ft per minute ( 762 m ) . 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 the wings strengthened and an addition of two fuel tanks , or alternatively two 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 . The Merlin 31 powered B Mk VII was built by de Havilland Canada . It was based on the B . V . and first flown on 24 September 1942 . It only saw service in Canada and only 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 . 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 " Cookie " , and all B Mk IXs built after that date were designed to allow them to be converted to carry the weapon . The B Mk IX had a maximum speed of , an economical cruise speed of at 20 , 000 ft , and at 30 , 000 ft , ceiling of , a range of , and a climb rate of 2 , 850 feet per minute ( 869 m ) . The IX could carry a maximum load of 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 . 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 " 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 , an economical cruise speed of at 20 , 000 ft , and at 30 , 000 ft , ceiling of , a range of , and a climb rate of 2 , 800 ft per minute ( 853 m ) . The type could carry 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 , a cruising speed of , ceiling of , a range of , and a climb rate of 2 , 700 ft per minute ( 823 m ) . A total of 174 B . 35s were delivered up to the end of 1945 . A further 100 were delivered from 1946 for a grand total of 274 , 65 of which were built by Airspeed Ltd . Fighters . Developed during 1940 , the first prototype of the Mosquito F Mk II was completed on 15 May 1941 . These Mosquitos were fitted with four Hispano cannon in the fuselage belly and four . 303 ( 7 . 7 mm ) Browning machine gun s mounted in the nose . On production Mk IIs the machine guns and ammunition tanks were accessed via two centrally hinged , sideways opening doors in the upper nose section . To arm and service the cannon the bomb bay doors were replaced by manually operated bay doors : the F and NF Mk IIs could not carry bombs . The type was also fitted with a gun camera in a compartment above the machine guns in the nose and was fitted with exhaust flame dampers to reduce the glare from the Merlin XXs . In August 1942 Britain experienced several incursions of high - altitude Luftwaffe bombers , including the Junkers Ju - 86P . As a result of these raids , starting in September 1942 , five Mosquito B Mk IV bombers were quickly converted into F Mk XV high - altitude , pressurised fighters , powered by two - stage Merlin 73s and 77s fitted with four - bladed propellers . The first of these conversions was " MP469 " , which was wheeled into the experimental shop on 7 September and first flew on 14 September . The bomber nose forward of the cockpit was cut off and a standard fighter nose , complete with four . 303 Brownings , grafted on in its place . The pressurised crew cabin retained the bomber ' s canopy structure , with a vee - shaped , two - piece windscreen , while the bomber ' s control wheel was replaced by the fighter ' s control stick . Extended , pointed , wingtips increased the wingspan to . The airframe was lightened by removing all armour plating , bullet - proofing from the fuel and oil tanks , and the outer wing and fuselage tanks ( leaving the inner wing tanks with a total capacity of ) . Other ancillary equipment was also removed , and smaller - diameter main wheels were fitted after the first few flights . At a loaded weight of the Mk XV was lighter than a standard Mk II , and reached an altitude of . Four more B Mk IVs were converted into F Mk XVs , and , in late 1942 , were further modified to become NF MK XVs . All fighters and fighter bombers , apart from the F Mk XV , featured a modified canopy structure incorporating a flat , single piece armoured windscreen , and the crew entry / exit door was moved from the bottom of the forward fuselage to the right side of the nose , just forward of the wing leading edge . The pilot was provided with a fighter - style control stick rather than a wheel . Night fighters . At the end of 1940 , the Air Staff ' s preferred night fighter design was the Gloster F . 18 / 40 ( derived from their F . 9 / 37 ) . However , although in agreement as to the quality of the Gloster company ' s design , the Ministry of Aircraft Production was concerned that Gloster would not be able to work on the F . 18 / 40 and also the jet fighter design , considered the greater priority . Consequently in mid - 1941 the Air Staff and MAP agreed that the Gloster aircraft would be dropped and the Mosquito considered for the night fighter requirement instead . The first production night fighter Mosquitos were designated NF Mk II . A total of 466 were built with the first entering service with No . 157 Squadron in January 1942 , replacing the Douglas Havoc . These aircraft were similar to the F Mk II , but were fitted with the AI Mk IV metric wavelength radar . The herring - bone transmitting antenna was mounted on the nose and the dipole receiving antennae were carried under the outer wings . A number of NF IIs had their radar equipment removed and additional fuel tanks installed in the bay behind the cannon for use as night intruders . These aircraft , designated NF II ( Special ) were first used by 23 Squadron in operations over Europe in 1942 . 23 Squadron was then deployed to Malta on 20 December 1942 , and operated against targets in Italy . Ninety - seven NF Mk IIs were upgraded with centimetric AI Mk VIII radar and these were designated NF Mk XII . The NF Mk XIII , of which 270 were built , was the production equivalent of the Mk XII conversions . The centimetric radar sets were mounted in a solid " thimble " ( Mk XII / XIII ) or universal " bull nose " ( Mk XVII / XIX ) radome , which required the machine guns to be dispensed with . Four F Mk XVs were converted to the NF Mk XV . These were fitted with AI Mk VIII in a " thimble " radome , and the . 303 Brownings were moved into a gun pack fitted under the forward fuselage . The NF Mk XIX was an improved version of the NF XIII . It could be fitted with American or British AI radars ; 220 were built . The NF Mk 30 was the final wartime variant and was a high - altitude version , powered by two Roll - Royce Merlin 76s . The NF Mk 30 had a maximum speed of at . It also carried early electronic countermeasures equipment . 526 were built . Other Mosquito night fighter variants which were planned for , but never built , included the NF Mk X and NF Mk XIV ( the latter based on the NF Mk XIII ) , both of which were to have two - stage Merlins . The NF Mk 31 was a variant of the NF Mk 30 , but powered by Packard Merlins . Mosquito night intruders of 100 Group , Bomber Command , were also fitted with a device called " Serrate " to allow them to track down German night fighters from their Lichtenstein B / C and SN - 2 radar emissions , as well as a device named " Perfectos " that tracked German IFF signals . After the war , two more night fighter versions were developed : The NF Mk 36 was similar to the Mosquito NF Mk 30 , but fitted with the American - built AI . Mk X radar . Powered by two Roll - Royce Merlin 113 / 114 piston engines ; 266 built . Max level speeds ( TAS ) with flame dampers fitted were at sea level , at , and at . The NF Mk 38 , 101 of which were built , was also similar to the Mosquito NF Mk 30 , but fitted with the British - built AI Mk IX radar . This variant suffered from stability problems and did not enter RAF service : 60 were eventually sold to Yugoslavia . According to the Pilot ' s Notes and Air Ministry ' Special Flying Instruction TF / 487 ' , which posted limits on the Mosquito ' s maximum speeds , the NF Mk 38 had a VNE of 370 knots ( 425 mph ) , without under - wing stores , and within the altitude range of sea level to . However , from 10 , 000 to the maximum speed was 348 knots ( 400 mph ) . As the height increased other recorded speeds were ; 15 , 000 to 320 knots ( 368 mph ) ; 20 , 000 to , 295 knots ( 339 mph ) ; 25 , 000 to , 260 knots ( 299 mph ) ; 30 , 000 to , 235 knots ( 270 mph ) . With two added 100 - gallon fuel tanks this performance fell ; between sea level and 15 , 000 feet 330 knots ( 379 mph ) ; between 15 , 000 to 320 knots ( 368 mph ) ; 20 , 000 to , 295 knots ( 339 mph ) ; 25 , 000 to , 260 knots ( 299 mph ) ; 30 , 000 to , 235 knots ( 270 mph ) . Little difference was noted above . Fighter - bombers . The FB Mk VI , which first flew on 1 June 1942 , was powered by two Merlin 21s or Merlin 25s , and introduced a re - stressed and reinforced " basic " wing structure capable of carrying single or bombs on racks housed in streamlined fairings under each wing , or up to eight RP - 3 25lb or 60 lb rockets . In addition fuel lines were added to the wings to enable single or drop tanks to be carried under each wing . The usual fixed armament was four 20 mm Hispano Mk . II cannon and four . 303 ( 7 . 7 mm ) Browning machine guns , while two or bombs could be carried in the bomb bay . Unlike the F Mk II , the ventral bay doors were split into two pairs , with the forward pair being used to access the cannon , while the rear pair acted as bomb bay doors . The maximum fuel load which could be carried was distributed between internal fuel tanks , plus two overload tanks , each of capacity , which could be fitted in the bomb bay , and two drop tanks . All - out level speed is often given as , however this speed applies to aircraft fitted with saxophone exhausts . The test aircraft ( " HJ679 " ) fitted with stub exhausts was found to be performing below expectations . It was returned to de Havilland at Hatfield where it was serviced . Its top speed was then tested and found to be , in line with expectations . 2 , 298 FB Mk VIs were built , nearly one - third of Mosquito production . 18 built by Airspeed Ltd were eventually modified to become FB . XVIIIs . Two were converted to TR . 33 carrier - borne , maritime strike prototypes . The FB Mk VI proved capable of holding its own with single - engine fighter aircraft in addition to bombing . For example , on 15 January 1945 Mosquito FB Mk VIs of 143 Squadron were engaged by 30 Focke - Wulf Fw 190 s from " Jagdgeschwader 5 " : nonetheless , the Mosquitos sank an armed trawler and two merchant ships , losing five Mosquitos ( two to flak ) but shooting down five Fw 190s . Another fighter - bomber variant was the Mosquito FB Mk XVIII ( sometimes known as the " Tsetse " ) of which 18 were purpose - built and 27 converted from Mk VIs . The Mk XVIII was armed with a Molins " 6 - pounder Class M " cannon : this was a modified QF 6 - pounder ( 57 mm ) anti - tank gun fitted with an auto - loader to allow both semi - or fully automatic fire . 25 rounds were carried , with the entire installation weighing . In addition , of armour was added within the engine cowlings , around the nose and under the cockpit floor to protect the engines and crew from the heavily armed U - boats which were intended to be the primary target of the Mk XVIII . Two or four . 303 ( 7 . 7 mm ) Browning machine guns were retained in the nose and were used to " sight " the main weapon onto the target . The Air Ministry initially suspected that this variant would not work , but tests proved otherwise . Although the gun provided the Mosquito with yet more anti - shipping firepower for use against U - boats , it required a steady approach run to aim and fire the gun , making it vulnerable to anti - aircraft fire . The gun had a muzzle velocity of and an excellent range of some 1 , 800 - 1 , 500 yards ( 1 , 650 - 1 , 370 m ) . It was sensitive to sidewards movement ; an attack required a dive from at a 30° angle with the turn and bank indicator on centre . A move during the dive could jam the gun . The prototype " HJ732 " was converted from a FB . VI and was first flown on 8 June 1943 . The effect of the new weapon was demonstrated on 10 March 1944 when Mk XVIIIs from 248 Squadron ( escorted by four Mk VIs ) engaged a German convoy of one U - boat and four destroyers , protected by 10 Ju 88s . Three of the Ju 88s were shot down . Pilot Tony Phillips destroyed one Ju 88 with four shells , one of which tore an engine off the Ju 88 . The U - boat was damaged . On 25 March , " U - 976 " was sunk by Molins - equipped Mosquitos . On 10 June , " U - 821 " was abandoned in the face of intense air attack from No . 248 Squadron , and was later sunk by a Liberator of No . 206 Squadron . On 5 April 1945 Mosquitos with Molins attacked five German surface ships in the Kattegat and again demonstrated their value by setting them all on fire and sinking them . A German " Sperrbrecher " ( " minefield breaker " ) was lost with all hands , with some 200 bodies being recovered by Swedish vessels . Some 900 German soldiers died in total . On 9 April , German U - boats " U - 804 " , " U - 843 " and " U - 1065 " were spotted in formation heading for Norway . All were sunk . U - 251 and U - 2359 followed on 19 April and 2 May 1945 . Despite the preference for rockets , a further development of the large gun idea was carried out using the even larger QF 32 - pounder , a gun based on the QF 3 . 7 inch AA gun designed for tank use , the airborne version using a novel form of muzzle brake . Developed to prove the feasibility of using such a large weapon in the Mosquito , this installation was not completed until after the war , when it was flown and fired in a single aircraft without problems , then scrapped . Designs based on the Mk VI were the FB Mk 26 , built in Canada , and the FB Mk 40 , built in Australia , powered by Packard Merlins . The FB . 26 improved from the FB . 21 using single stage Packard Merlin 225s . Some 300 were built and another 37 converted to T . 29 standard . 212 FB . 40s were built by de Havilland Australia . Six were converted to PR . 40 ; 28 to PR . 41s , one to FB . 42 and 22 to T . 43s tactical assault aircraft . Most were powered by Packard - built Merlin 31 or 33s . Trainers . The Mosquito was also built as the Mosquito T Mk III two - seat trainer . This version , powered by two Rolls - Royce Merlin 21s , was unarmed and had a modified cockpit fitted with dual control arrangements . A total of 348 of the T Mk III were built for the RAF and Fleet Air Arm . de Havilland Australia built 11 T Mk 43 trainers , similar to the Mk III . Torpedo - bombers . To meet specification N . 15 / 44 for a navalised Mosquito for Royal Navy use as a torpedo bomber , de Havilland produced a carrier - borne variant . A Mosquito FB . VI was modified as a prototype designated Sea Mosquito TR Mk 33 with folding wings , arrester hook , thimble nose radome , Merlin 25 engines with four - bladed propellers and a new oleo - pneumatic landing gear rather than the standard rubber - in - compression gear . An order for 100 TR . 33s was placed although only 50 were built at Leavesden . Armament was four 20 mm cannon , two 500 lb bombs in the bomb bay , ( another two could be fitted under the wings ) eight 60 lb rockets ( four under each wing ) and a standard torpedo under the fuselage . The first production TR . 33 flew on 10 November 1945 . This series was followed by six Sea Mosquito TR Mk 37s , which differed in having ASV Mk XIII radar instead of the TR . 33 ' s AN / APS - 6 . Target tugs . The Royal Navy also operated the Mosquito TT Mk 39 for target towing . A number of B Mk XVIs bombers were converted into TT Mk 39 target tug aircraft . The RAF ' s target tug version was the Mosquito TT Mk 35 which were the last aircraft to remain in operational service , with No 3 CAACU at Exeter , finally being retired in 1963 ( these aircraft were then featured in the film 633 Squadron ) . Two ex - RAF FB . 6s were converted to TT . 6 standard at Manchester ( Ringway ) Airport by Fairey Aviation in 1953 – 1954 , being delivered to the Belgian Air Force for use as towing aircraft from the Sylt firing ranges . Canadian - built . A total of 1 , 133 ( to 1945 ) Mosquitos were built by De Havilland Canada at Downsview Airfield in Downsview Ontario ( now Downsview Park in Toronto Ontario ) . Highball . A number of Mosquito IVs were modified by Vickers - Armstrongs to carry Highball " bouncing bomb s " and were allocated Vickers Type numbers : Production . Details . In England , fuselage shells were mainly made by furniture companies , including Ronson , E . Gomme , Parker Knoll and Styles & Mealing . Some of the specialized wood veneer used in the construction of the Mosquito was made by Roddis Manufacturing in Marshfield , Wisconsin , United States . Hamilton Roddis had teams of young women ironing the ( unusually thin ) strong wood veneer before shipping to the UK . Wing spars were made by J . B . Heath and Dancer & Hearne . Many of the other parts , including flaps , flap shrouds , fins , leading edge assemblies and bomb doors were also produced in High Wycombe , Buckinghamshire , which was well suited to these tasks because of a well - established furniture manufacturing industry . Dancer & Hearne processed much of the wood from start to finish , receiving timber and transforming it into finished wing spars at their High Wycombe factory . About 5 , 000 of the 7 , 781 Mosquitos made contained parts made in High Wycombe . In Canada , fuselages were built in the Oshawa , Ontario plant of General Motors of Canada Limited . These were shipped to De Havilland Canada in Toronto for mating to fuselages and completion . As a secondary manufacturer , de Havilland Australia started construction in Sydney . These production lines added 1 , 133 from Canada and 212 from Australia . Total Mosquito production was 7 , 781 of which 6 , 710 were built during the war . The ferry operation of the Mosquito from Canada to the war front was problematic , as a small fraction of the aircraft mysteriously disappeared over mid - Atlantic . The theory of " auto - explosion " was offered , and , although a concentrated effort at de Havilland Canada to address production problems with engine and oil systems reduced the number of aircraft lost , the actual cause of the losses was not known . The company introduced an additional five hours flight testing to " clear " production aircraft before the ferry flight . By the end of the war , nearly 500 Mosquito bombers and fighter - bombers had been delivered successfully by the Canadian operation . In total , both during the war and after , de Havilland exported 46 FB . VIs and 29 PR . XVIs to Australia , two FB . VI and 18 NF . 30s to Belgium , approximately 205 FB . 26 , T . 29 and T . 27s to Nationalist China ( 5 of these were captured by the People ' s Liberation Army during the Chinese Civil War ) , 19 FB . VIs to Czechoslovakia in 1948 , 6 FB . VIs to Dominica , a few B . IVs , 57 FB . VIs , 29 PR . XVIs and 23 NF . XXXs to France . Some T . IIIs were exported to Israel along with 60 FB . VIs , and at least five PR . XVIs and 14 naval versions . Four T . IIIs , 76 FB . VIs , one FB . 40 and four T . 43s were exported to New Zealand . Three T . IIIs were exported to Norway , and 18 FB . VIs which were later converted to night fighter standard . South Africa received two F . II and 14 PR . XVI / XIs and Sweden received 46 NF . XIXs . Turkey received 96 FB . VIs and several T . IIIs , and Yugoslavia had 60 NF . 38s , 80 FB . VIs and three T . IIIs delivered . Operational history . The de Havilland Mosquito operated in many roles during the Second World War , being tasked to perform medium bomber , reconnaissance , tactical strike , anti - submarine warfare and shipping attack and night fighter duties , both defensive and offensive , until the end of the war . The Mosquito was first announced publicly on 26 September 1942 after the Oslo Mosquito raid of 25 September . The Mosquito flew its last official European war mission on 21 May 1945 , when Mosquitos of 143 Squadron and 248 Squadron RAF were ordered to continue to hunt German submarines that might be tempted to continue the fight ; instead of submarines all the Mosquitos encountered were passive E - boat s . Mosquitos were widely used by the RAF Pathfinder Force , marking targets for the main night - time strategic bombing force , as well as flying " nuisance raids " in which Mosquitos often dropped 4 , 000 lb " Cookies " . Despite an initially high loss rate , the Mosquito ended the war with the lowest losses of any aircraft in RAF Bomber Command service . Post war , the RAF found that when finally applied to bombing , in terms of useful damage done , the Mosquito had proved 4 . 95 times cheaper than the Lancaster . In April 1943 , in response to " political humiliation " caused by the Mosquito , Hermann Göring ordered the formation of special " Luftwaffe " units ( " Jagdgeschwader 25 " , commanded by " Oberstleutnant " Herbert Ihlefeld and " Jagdgeschwader 50 " , under " Major " Hermann Graf ) to combat the Mosquito attacks , though these units , which were " little more than glorified squadrons " , were not very successful against the elusive RAF aircraft . In one example of the daylight precision raids carried out by the Mosquito , on 20 January 1943 , the 10th anniversary of the Nazis ' seizure of power , a Mosquito attack knocked out the main Berlin broadcasting station while Commander in Chief Reichsmarschall Hermann Göring was speaking , putting his speech off air . Göring himself had strong views about the Mosquito , lecturing a group of German aircraft manufacturers in 1943 that he could " go berserk " when faced with the Mosquito , which made him " green and yellow with envy . " The Mosquito also proved a very capable night fighter . Some of the most successful RAF pilots flew the Mosquito . Bob Braham claimed around a third of his 29 kills in a Mosquito , flying mostly daytime operations , while on night fighters Wing Commander Branse Burbridge claimed 21 kills , and Wing Commander John Cunningham claimed 19 of his 20 victories at night on Mosquitos . Mosquito ' s of No . 100 Group RAF were responsible for the destruction of 257 German aircraft from December 1943 — April 1945 . Mosquito fighters from all units accounted for 487 German aircraft during the war , the vast majority were night fighters . One Mosquito is listed as belonging to German secret operations unit " Kampfgeschwader 200 " , which tested , evaluated and sometimes clandestinely operated captured enemy aircraft during the war . The aircraft was listed on the order of battle of " Versuchsverband OKL " s , " 2 Staffel " , " Stab Gruppe " on 10 November and 31 December 1944 . However , on both lists , the Mosquito is listed as unserviceable . Survivors . There are approximately 30 non - flying Mosquitos around the world with only one airworthy example . The largest collection of Mosquitos is at the de Havilland Aircraft Heritage Centre in the United Kingdom , which owns three aircraft , including the first prototype , " W4050 " , potentially the only initial prototype of a Second World War aircraft design still in existence in the 21st century . The airworthy Mosquito in flying condition , Mosquito FB . 26 " KA114 " , was built in Canada in 1945 and was restored by Avspecs Limited of Ardmore , New Zealand ; its first post - restoration flight was on 27 September 2012 . The third , fourth , fifth and sixth flights were watched by several thousand spectators at a special air show at Ardmore on 29 September . The aircraft is owned by Jerry Yagen and is due to be moved to its new home at the Military Aviation Museum , a large collection of flying historic aircraft in Virginia Beach , Virginia . A complete set of forms , jigs and moulds will allow for new Mosquitos to be built . Sixteen years earlier , in July 1996 , the then - only airworthy Mosquito , " RR299 , G - ASKH " , was destroyed in an airshow accident at Barton , Manchester ; both aircrew were killed . A temporary loss of power in the left engine caused the pilot ( with over 10 , 000 hours of flying experience ) to lose control at low level ; " RR299 " hit the ground at high speed in nearby woodland and disintegrated .