de Havilland Mosquito

DH.98 Mosquito
Mosquito B Mark IV Series 2, DK338, in flight after completion c. 1942. IWM Collection
Role	Fast bomber, fighter-bomber, and night fighter
Manufacturer	de Havilland Aircraft Company
Designer	Ronald Bishop
First flight	25 November 1940
Introduction	1941
Retired	1956
Primary users	Royal Air Force Royal Canadian Air Force United States Army Air Force
Produced	1940–1950
Number built	7,781

The de Havilland Mosquito was a British combat aircraft that excelled in a number of roles during the Second World War. Originally conceived as a fast day bomber, uses of the Mosquito included: tactical bomber, pathfinder, day or night fighter, fighter-bomber, intruder, maritime strike and photo reconnaissance aircraft. It was also used as the basis for a single-seat heavy fighter, the de Havilland Hornet. It served with the Royal Air Force (RAF) and many other air forces both in the Second World War and postwar (see Operators below). The Mosquito was known affectionately as the "Mossie" to its crews and was also known as "The Wooden Wonder" or "The Timber Terror".

The Mosquito inspired admiration from all quarters, including the Commander-in-Chief of the Luftwaffe, Hermann Göring. Göring was due to address a parade in Berlin in the morning of 30 January 1943, commemorating the 10th anniversary of the Nazis' being voted into power. The low level attack of three 105 Squadron Mosquito B Mk. IV on the main Berlin broadcasting station put Reichsmarschall Göring off the air for more than an hour, as he was about to launch into a scheduled speech.

The Reichsmarschall was not amused:

“	In 1940 I could at least fly as far as Glasgow in most of my aircraft, but not now! It makes me furious when I see the Mosquito. I turn green and yellow with envy. The British, who can afford aluminium better than we can, knock together a beautiful wooden aircraft that every piano factory over there is building, and they give it a speed which they have now increased yet again. What do you make of that?	”
	— Hermann Göring, January 1943,

The Mosquito inspired a German imitation, the Focke Wulf Ta 154 Moskito, which, like its namesake, was constructed of wood.

Design and development

Throughout the 1930s, de Havilland had established a reputation in developing innovative high-speed aircraft such as the DH.88 Comet mailplane and DH.91 Albatross airliner that had already successfully employed the composite wood construction that the Mosquito would use. When a new Air Ministry contract was specified for new bombers, de Havilland applied, to their surprise.

Their initial design had started off as something very similar to the existing heavy bombers, armed with three gun turrets and a six-man crew, powered by two Rolls-Royce Merlin engines. However the resulting design had very poor performance. The designers started looking for ways to improve it, including the addition of another pair of engines. After more work on the concept they started moving in the other direction instead, trying shave off everything that was unneeded in order to lower weight. As each of the gun turrets was eliminated the performance of the aircraft continued to improve, until they realized that by removing them all the aircraft would be so fast it would not need guns anyway. What emerged was an entirely different concept, a small two-engine, two-person aircraft so fast that nothing in the sky could catch it. It could carry 1,000 lb (454 kg) of bombs for 1,500 miles (2,400 km) at a speed of almost 400 mph (644 km/h), which was almost twice that of current British bombers at the time.

In October 1938 the Ministry rejected their proposal, skeptical about the idea of a wooden plane and the concept of the unarmed bomber. They informed de Havilland that their contribution was best served by constructing wings for one of the existing bomber aircraft programs. Regardless, de Havilland was convinced the idea was sound, and continued development on their own. The support of Sir Wilfrid Freeman eventually proved decisive and a contract for fifty aircraft, including one prototype, was finally placed under B.1/40 on 1 March 1940. Design and prototype construction was able to begin almost immediately, but work was cancelled again after Dunkirk in order to focus on existing types. The need for fighters became extremely pressing, and the contract was re-instated in July, but now ordering 20 bombers and 30 heavy fighters instead. The contract was later changed again, adding a prototype for a dedicated reconnaissance version that was even further stripped down for higher speeds.

The Battle of Britain raged while the prototypes were being built, and 25% of the factory time was lost in the bomb shelters. Nevertheless, the original bomber prototype, W4050, was rolled out on 19 November 1940, and first flew on 25 November, only ten months after the go-ahead. The original estimates were that as it was twice the wetted area and over twice the weight of the 1940 Spitfire, but also with twice its power, it would end up being 20 mph (32 km/h) faster. Over the next few months it managed to prove this estimate wrong, beating it in testing at Boscombe Down in February 1941 at a top speed of 392 mph (631 km/h) at 22,000 ft (6,705 m) altitude. Construction of a prototype fighter was carried out at the secret Salisbury Hall facility, and on 15 May 1941, Geoffrey De Havilland personally flew W4052 off a 450 foot field beside the shed it was built in. The first reconnaissance prototype, W4051, followed on 10 June 1941.

During testing it was demonstrated that it had the power and internal capacity to carry not the 1000 lbs of bombs as originally specified, but four times that figure. In order to better support the higher loads the aircraft was capable of, the wingspan was increased from 52 ft 6in (16.00 m) to 54 ft 2in (16.51 m). It was also fitted with a larger tailplane, improved exhaust system, and lengthened nacelles that improved stability. These modifications became standard across the production versions.

Construction

The bulk of the Mosquito was made of custom plywoods. The fuselage was built by forming up a plywood made of 3/8" sheets of Ecuadorean balsawood sandwiched between sheets of Canadian birch. These were formed inside large concrete moulds, each holding one half of the fuselage, split vertically. While the casein-based glue in the plywood dried, carpenters cut a sawtooth join into their edges while other workers installed the controls and cabling. When the glue was completely dried, the two halves were glued and screwed together. A covering of doped Madapolam (a fine plain woven cotton) fabric completed the unit.

The wings were similar but used different materials and techniques. The wing was built as a single unit, not two sides, based on two birch plywood boxes as spars fore and aft. Plywood ribs and stringers were glued and screwed to form the basic wing shape. The skinning was also birch plywood, one layer thick on the bottom and doubled up on the top. Between the two top layers was another layer of fir stringers. Building up the structure used an enormous number of brass screws, 30,000 per wing. The wing was completed with wooden flaps and aluminium ailerons.

When both parts were complete the fuselage was lowered onto the wing, and once again glued and screwed together. The remainder consisted of wooden horizontal and vertical tail surfaces, with aluminium control surfaces. Engine mounts of welded steel tube were added, along with simple landing gear oleos filled with rubber blocks. The total weight of castings and forgings used in the aircraft was only 280 lbs.

The glue used was initially casein-based. It was changed to a formaldehyde-based preparation when the Mosquito was introduced to fighting in semi-tropical and tropical climates, after some unexplained crashes led to the suspicion that the glue was unable to withstand the climate. De Havilland also developed a technique to accelerate the glue drying by heating it using microwaves.

In England fuselage shells were mainly made by E. Gomme, Parker Knoll and Styles & Mealing. 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 dexterous young women ironing the (unusually thin) strong wood veneer product 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 due to a well established furniture making industry. Dancer and Hearne processed much of the wood from start to finish, receiving timber and transforming it into finished wing spars at their High Wycombe factory.

Around 5,000 of the total 7,781 Mosquitos ever 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 of Canada in Toronto for mating to fuselages and completion. De Havilland Australia started construction in Sydney. These production lines added 1,134 from Canada and 212 from Australia.

Operational service

The Mosquito is often described as having been faster than enemy fighters, although this is not completely true. On its introduction to service, the aircraft was about as fast as the front-line German fighters that opposed it, the BF 109F and Fw 190A. Nonetheless their speed margin was slim enough that, by the time those aircraft could reach interception altitude, the Mosquito would have completed its bombing run and would be racing for home. Advancements in those aircraft would eventually outpace performance improvements in the Mosquito, but it was always an elusive target even in the day.

At night, however, no Luftwaffe aircraft came even close. At the time it was introduced, most of the dedicated night fighter groups were equipped with aircraft like the Bf 110 or Junkers Ju 88 of much lower performance. Although there were several attempts to address this by introducing a new night fighter of greatly improved performance, a variety of problems from engine troubles to the increasing bombing campaign meant that they never matured. The Heinkel He 219 and Junkers Ju 388 that were technically the Mosquito's equal simply never entered large-scale production. Their tiny numbers meant they were never a serious threat, and in the night bombing role the Mosquito went largely unopposed for the entire war.

With the introduction of the nitrous oxide boosted Bf 109s and the jet-powered Me 262 late in the war, the Luftwaffe had interceptors with a clear speed advantage over the Mosquito. The PR Mk 32 photo reconnaissance version of the Mosquito attempted to counter this with long-span wings, special high-altitude superchargers and the elimination of as much weight as possible, raising its cruising altitude to 42,000 ft (12,800 m). Even with these changes, the Mosquito was not totally immune; in December 1944, one was intercepted at maximum altitude.

RAF Bomber Operations

The first bomber squadrons to receive the Mosquito B IV used it for several low-level daylight raids. One was carried out in the morning of 30 January 1943, against a Nazi rally in Berlin, giving the lie to the speaker's (Reichmarschall Hermann Göring's) claim that such a mission was impossible. Not content with this, Mosquitos from RAF No 139 Squadron went to Berlin in the afternoon and tried to interrupt an important speech by Joseph Goebbels, Germany's Propaganda Minister.

Mosquito bomber versions were used as part of Bomber Command; the Pathfinders in No. 8 Group and the Light Night Strike Force (LNSF). The LNSF carried out high speed night raids with precision aiming and navigation. Their mission was twofold: first, they would target small but vital installations; and second, they would act as a diversion from the raids of the heavy bombers, simulating large formations through the use of chaff. On nights when no heavy bomber raid was planned, the LNSF would often strike so the German air defences would not get a rest.

As part of No. 8 Group Mosquitos took part in many bombing operations as pathfinders, marking targets accurately with flares for later attack by massive formations of heavy bombers. Bomber Command Mosquitos flew over 28,000 operations, dropping 35,000 tons of bombs, and losing just 193 aircraft in the process (a loss rate of 0.7%, compared to a 2.2% loss rate for the four engined heavies). It has been calculated that a Mosquito could be loaded with a 4,000 lb. "cookie" bomb, fly to Germany, drop the bomb, return, bomb up and refuel, fly to Germany again and drop a second 4,000 lb bomb and return, and still land before a Stirling (the slowest of Bomber Command's four-engined bombers) which left at the same time armed with a full bomb load, could strike Germany.

A Mosquito IX also holds the record for the most missions flown by an Allied bomber in the Second World War. LR503, "F for Freddie", first serving with 109 and subsequently 105 Squadron, flew 213 sorties during the war, only to crash on 10 May 1945, two days after VE Day at Calgary airport during a victory tour, an accident attributed to pilot error.

Highball

At the same time that Barnes Wallis was designing the famous Upkeep to destroy German dams he also designed a smaller version — Highball — for attacks on enemy shipping. It was decided that the Mosquito was an ideal aircraft to carry two of these weapons in modified bomb bays. To this end No. 618 Squadron RAF was formed as part of Coastal Command, although the weapons were never used operationally.

Night fighter

The use of the Mosquito as a night fighter came about when the Air Ministry project for a night fighter (based on the Gloster F.9/37) was terminated to concentrate production on other types.

The first fighter Mosquito introduced into service was the NF Mk II in mid-1942, with four 20 mm Hispano cannon in the fuselage belly and four .303 in. Browning machine-guns mounted in the nose. It carried Aircraft Interception radar (AI) Mk IV / Mk V when operating as a defensive night fighter over the UK, although at the time this was omitted from Mk IIs operating as night "Intruders", roaming over Europe at night to cause maximum disruption to lines of communications and flying operations.

In May 1942, the NF Mk II scored its first kill and until the end of the war, Mosquito night fighters claimed approximately 600 enemy aircraft, along with 600 V-1 flying bombs. This variant also operated over Malta, Italy, Sicily and North Africa from late 1942 on. The Mosquito NF XII became the first aircraft to carry the highly effective centimetric radar.

From early 1944 the Mosquito also operated in the bomber support role with Bomber Command's 100 Group, their task being to harass the Luftwaffe NachtJagd (night fighters) attacking the bomber streams over Germany. Some 258 Luftwaffe night fighters were claimed destroyed by the Group, for the loss of some 70 Mosquitoes. The omniprescence of the potent night fighter threat led to what the Luftwaffe crews dubbed "Mosquitoschreck" (Mosquito scare), as the German aircrews were never sure when or where they may come under attack from the marauding 100 Group fighters and indirectly led to a high proportion of both aircraft wastage from crashes as night fighters hurried in to land to avoid the Mosquito threat (real or imagined).

The Mosquito night fighters would meet their nemesis only in February, 1945, when Messerschmitt 262 jet fighters were being flown at night by pilots from 10./NJG 11. The commander of this unit, Oberleutnant Kurt Welter, claimed perhaps 25 Mosquitos shot down by night and two further Mosquitos by day while flying the Me 262, adding to his previous seven Mosquito kills in "hot-rodded" Bf 109G-6/AS or Fw 190 A-8 fighters. This effort was too little and too late to have any effect of the outcome of the war.

Fighter-bomber versions

Operational experience in its varied roles quickly led to the development of a versatile fighter-bomber version; the FB VI, which first saw service in early 1943. The Mark VI had a strengthened wing for external loads and along with its standard fighter armament could carry two 250 lb bombs in the rear of the bomb bay and two 250 lb bombs under the wings, or eight wing-mounted rockets. Later up-engined versions could carry 500 lb bombs. The FB VI became the most numerous version of the Mosquito (2,292 built), equipping the day bomber 2 Group, the intruder squadrons of Fighter Command and 2nd Tactical Air Force, and the strike wings of Coastal Command, who used the variant as a potent anti-shipping aircraft armed with eight "60 lb" rockets.

One of the higher risk uses of the fighter-bomber Mosquito FB VI was by 21 Sqn., 464(RAAF) Squadron and 487(NZ) Squadron of No. 2 Group, 2nd Tactical Air Force in Operation Jericho, a mission to destroy the walls and guards' quarters of Amiens prison to allow members of the French Resistance to escape. In the aftermath of the operation the Mosquito of Group Captain Percy Pickard was shot down.

On 11 April 1944, after a request by Dutch resistance workers, six Mosquito FB VIs of No. 613 (City of Manchester) Squadron made a pinpoint attack at rooftop height on the Kunstzaal Kleizkamp Art Gallery in The Hague, Netherlands, which was being used by the Gestapo to store the Dutch Central Population Registry. Their bombs, a mixture of high explosive and incendiary, went in through the doors and windows and the incriminating records were burned. Only persons in the building were killed - nearby civilians in a bread queue were unharmed.

On 21 March 1945, another similar raid, Operation Carthage, again by 21 Sqn., 464(RAAF) Sqn. and 487(NZ) Sqn. involved a very low-level bombing attack on the Gestapo headquarters in the Shellhus, near the centre of Copenhagen, Denmark. Twenty Mosquitos were involved, split into three attack waves. They were escorted by 30 RAF Mustangs. The main attack on the Gestapo headquarters caused the death of 55 German soldiers and 47 Danes working for the Gestapo, together with destruction of the Gestapo records in the headquarters. Eight Gestapo prisoners were killed while 18 prisoners escaped. Unfortunately, during the raid a Mosquito flying in the first wave of the attack struck a tall lamp-post and crashed into a nearby Catholic school (the French school). Mosquitos of the third wave bombed this area by mistake causing the death of 86 children, ten nuns, eight teachers and 21 other civilians. No civilians were killed during the main attack. Four Mosquitos were lost and nine pilots/crew members died. The attack was requested several times by Danish resistance workers, but was found to be too dangerous by the RAF. The attack did save the life of many Danish resistance workers, due to the fact that the Gestapo archives and organisation were severely damaged.

USAAF

The United States Army Air Forces (USAAF) ordered 120 Mosquitos for photographic reconnaissance, but only 40 were delivered and given the U.S. designation F-8 (six Canadian-built B Mk VII and 34 B Mk XX). Only 16 reached Europe, where 11 were turned over to the RAF and five were sent to Italy. The RAF provided 145 PR Mk XVI aircraft to the Eighth Air Force between 22 April 1944 and the end of the war. These were used for a variety of weather, photographic, and night reconnaissance missions; as chaff dispensers; as scouts for the heavy bomber force; on "Red Stocking" OSS missions; and as H2X Mickey platforms by the 802d Reconnaissance Group (Provisional), later re-named the 25th Bomb Group (Reconnaissance). The 25th BG flew 3,246 sorties and lost 29 PR Mk XVIs on operations.

BOAC

Between 1943 and the end of the war, Mosquitos were used as transport aircraft on a regular route over the North Sea between Leuchars in Scotland and Stockholm. Lockheed Hudsons and Lodestars were also used but these slower aircraft could only fly this route at night or in bad weather to avoid the risk of being shot down. During the long daylight hours of summer, the Mosquito was the only safe alternative.

Because Sweden was neutral, the aircraft carried civilian markings and were operated by Norwegian officers, who were nominally "civilian employees" of BOAC. They carried small, high value cargos such as precision ball bearings and machine-tool steel. Occasionally, important passengers were carried in an improvised cabin in the bomb bay, one notable passenger being the physicist Niels Bohr, who was evacuated from Stockholm in 1943 in an unarmed Mosquito sent by the RAF. The flight almost ended in tragedy as Bohr did not don his oxygen equipment as instructed, and passed out. He would have died had not the pilot, surmising from Bohr's lack of response to intercom communication that he had lost consciousness, descended to a lower altitude for the remainder of the flight. Bohr's comment was that he had slept like a baby for the entire flight.

Post-Second World War

Mosquitos flying with the Israeli Air Force saw action during the 1956 Suez Crisis. Although, at the time, the Mosquito was being taken out of service, 13 aircraft of various marks were taken out of storage. An additional 13 TR 33 Mosquitos were purchased from a British scrap dealer in 1954.

Sweden purchased 60 ex-RAF Mk XIX Mosquitos in 1948 to be used as a night fighter under the J 30 designation. The aircraft were assigned to the F1 Wing at Västerås, thereby becoming the first (and only) dedicated night fighter unit of the Swedish Air Force. Its Mosquitos were replaced by jet fighters, de Havilland Venom Mk 51s, (designated J 33) in 1953. One-third of the J 30s crashed or broke down during service, mainly due to rudder problems. However, Swedish Air Force General Björn Bjuggren writes in his memoirs that mechanical problems in the swivelling nose-mounted radar antenna caused destructive vibrations that broke apart one or two J 30s in the air.

Notable pilots

• "Bob" John Randall Daniel Braham – The highest decorated RAF airman of the Second World War and a top night fighter ace.
• Branse Burbridge – the RAF highest scoring Mosquito night fighter ace
• Leonard Cheshire VC – British No. 617 Squadron RAF commander (and successor to Guy Gibson); one of the most distinguished exponents of precision marking and of the Pathfinders; he later distinguished himself by devoting his life to the care of the disabled and terminally ill and founded the Cheshire Homes. Cheshire's 1944 VC cited his dive over Munich in a Mosquito, enduring "withering" fire for many minutes.
• Sidney Cotton – Australian spy and photographic reconnaissance pioneer
• John "Cats Eyes" Cunningham – British night fighter pilot
• Geoffrey de Havilland Jr – son of the founder and chief test-pilot of the firm, carried out the maiden flight of the de Havilland Mosquito.
• Bill Edrich – English international cricketer, who played against Miller. Graduated from Blenheims to Mosquitos. Was awarded the DFC and became a Squadron Leader.
• Guy Gibson – British 617 Sqn commander; killed when his Mosquito crashed in the Netherlands while returning to England from a mission.
• Kirk Kerkorian – Worked as a ferry pilot for Mosquitos from Canada to Britain and elsewhere during WWII. The North Atlantic route was dangerous; the pay was high — $1000 per trip. with a section of the Las Vegas Review-Journal book, The Top 100, citing a 1974 biography by Dial Torgerson Kerkorian, An American Success Story.
• Keith Miller – Australian international cricketer, regarded by many as the greatest Australian all-rounder. In later life when asked how he dealt with pressure on the cricket field, Miller replied: "Pressure is [having] a Messerschmitt up your arse, playing cricket is not."
• Bolesław Orliński DFC – famous Polish pilot who flew a Breguet 19 from Warsaw-Tokio-Warsaw in 1926 and, with a PZL P.24, set a speed record on 28 June 1934. Commanding officer of Polish 305 Squadron, he flew a Mosquito in a mission against German prison camp in Lille and a large German fuel dump at Nomexy.
• Percy Charles Pickard DFC, DSO, and 2 bars – English Group Captain who starred in film Target For Tonight early in the war. Later became Group Captain and was shot down and killed during Operation Jericho, the raid on Amiens Prison.
• Erik Hazelhoff Roelfzema – Dutch resistance fighter and secret agent flew 72 sorties for the 139th Pathfinder squadron and wrote Soldier of Orange.
• Kenneth Wolstenhome – Was a Flight Lieutenant in No. 105 Squadron RAF. He later became the presenter and commentator on the BBC Match of the Day football programme. He spoke the widely repeated words "some people are on the pitch ... they think it's all over... it is now" as Geoff Hurst scored the fourth goal in England's 4-2 World Cup Final win over West Germany in 1966.

Variants

Prototypes

The original Mosquito design dated from 1938, but it was not until March 1940 that there was sufficient interest in the aircraft for construction to commence. Three prototypes were built, each with a different configuration. The first to fly was the bomber prototype W4050 on 25 November 1940, followed by the night fighter model on 15 May 1941 and the photo-reconnaissance model on 10 June 1941.

• Mosquito Mk I : First prototype aircraft.
• Mosquito Mk II : Second prototype aircraft.

Photo-reconnaissance aircraft

The photo-reconnaissance model became the basis for the Mosquito PR Mk I, while the bomber model became the Mosquito B Mk IV, of which 273 were built. The first operational sortie by a Mosquito was made by a PR Mk I on 20 September 1941, and the Mk IV entered service in May 1942 with No. 105 Squadron. The B Mk IV could accommodate 4 × 500 lb (227 kg) bombs in the bomb bay, and either two drop tanks or two additional 500 lb bombs on wing hardpoints.

• Mosquito PR.Mk IV : This designation was given to 32 Mosquito B.Mk IV bombers, converted into two-seat photo-reconnaissance aircraft.
• Mosquito PR.Mk VIII : Photo-reconnaissance version. Powered by two Rolls-Royce Merlin 31 piston engines. 25 built.
• Mosquito PR.Mk IX : Photo-reconnaissance version based on the Mosquito B.Mk IX bomber aircraft. Powered by two 1,680-hp (1253-kW) Merlin 72 piston engines.
• Mosquito PR.Mk 32 : Long-range photo-reconnaissance version. Powered by two 1,960-hp (1260-kW) Rolls-Royce Merlin 32 piston engines. Five conversions.
• Mosquito PR.Mk 34 : Very long-range photo-reconnaissance version. Addition fuel was carried in a bulged bomb-bay. 50 built.

Bomber aircraft

The Mosquito B.Mk IX was a high-altitude bomber variant, but the most numerous bomber version was the Mosquito B.Mk XVI of which about 1,200 were built. The Mosquito bombers could carry a 4,000 lb. (1 816 kg) " blockbuster" bomb in their internal bomb bay. This required a bulged bomb bay which could alternatively accommodate up to six 500 lb bombs on an Avro carrier. Mosquitos were widely used by the RAF Pathfinder Force which marked targets for night-time strategic bombing. Despite an initially high loss rate, the Mosquito ended the war with the lowest losses of any aircraft in RAF Bomber Command service. The RAF found that when finally applied to bombing, in terms of useful damage done, the Mosquito had proved 4.5 times cheaper than the Lancaster; and they never specified a defensive gun on a bomber thereafter. Special Luftwaffe units (Jagdgruppe 25 and Jagdgruppe 50) were formed to combat the Mosquito attacks, though they were rather unsuccessful and the Luftwaffe considered the Mosquito a superior implementation of their own " Schnellbomber" concept.

• Mosquito B.Mk V : One prototype bomber aircraft fitted with underwing pylons. One built.
• Mosquito B.Mk 35 : Long-range high-altitude bomber version. Fitted with a pressurised cockpit. 122 built.

Fighter Aircraft

Developed during 1940, the Mosquito F Mk II was developed and the first prototype was completed on 15 May 1941. These aircraft were fitted with four 20 mm Hispano cannon in the fuselage belly and four 0.303 in. Browning machine guns mounted in the nose. This fit required the movement of the crew ingress/egress door from the bottom to the right side of the nose. The aircraft also featured a revised windscreen, with flat bullet proof panels in front, as opposed to the original design.

Night fighter aircraft

The first production night fighter Mosquitos were designated the Mosquito NF Mk II. 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 transmit antenna was mounted on the nose and the dipole receive antennae were carried under the outer wings. A number of NF IIs had their radar equipment removed and additional fuel tanks installed for use as night intruders. These aircraft, designated NF II (Special) were first used by 23 Squadron in operations over Europe in 1942. No. 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 centrimetric AI Mk VIII radar and these were designated the Mosquito NF.Mk XII. The Mosquito 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 "bull nose" (Mk XVII / XIX) radome, which required the machine guns to be dispensed with. The other night fighter variants were the Mk XV, Mk XVIII (converted Mk IIs), Mk XIX and Mk 30. The last three marks mounted the U.S.-built AI Mk X radar.

• Mosquito NF Mk X: Unbuilt night fighter version.
• Mosquito NF Mk XI: Unbuilt night fighter version.
• Mosquito NF Mk XIV: Unbuilt night fighter version.
• Mosquito NF Mk XV: This designation was given to five Mosquito B.Mk IV bombers, which were converted into two-seat high-altitude night fighters.
• Mosquito NF Mk XVII: Designation for 99 NF.II conversions, with single-stage Merlin 21, 22, or 23 engines, but British AI.X (US SCR-720) radar.
• Mosquito NF Mk XVIII: This designation was given to 100 Mosquitos NF.Mk IIs, which were fitted with the American AI.Mk X radar.
• Mosquito NF Mk XIX: Improved version of the Mosquito NF XIII night fighter aircraft. It could be fitted with American or British AI radars. 220 built.
• Mosquito NF Mk 30: High-altitude night fighter version. Powered by two 1,710-hp (1275-kW) Roll-Royce Merlin 76 piston engines. It also carried early ECM equipment. 526 built.
• Mosquito NF Mk 31: Unbuilt night fighter version.

After the war, two more night fighter versions were developed, the NF Mk 36 and the NF Mk 38.

• Mosquito NF Mk 36: Similar to the mosquito NF.Mk 30 night fighter, but fitted with the American-built AI.Mk X radar. Powered by two 1,690-hp (1260-kW) Roll-Royce Merlin 113/114 piston engines. 266 built.
• Mosquito NF Mk 38: Similar to the Mosquito NF.Mk 30 night fighter, but fitted with the British-built AI Mk IX radar. 50 built.

To warn German night fighters that they were being tracked by these radars, the Germans introduced Naxos ZR radar detectors.

Mosquito night intruders of No. 100 Group RAF, 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.

Fighter-bomber aircraft

The most numerous Mosquito variant was the FB Mk VI fighter-bomber of which 2,718 were built. Originally converted from a Mk II, the Mk VI first flew in February 1943. Designed for a fighter-bomber role, the Mk VI could carry two 250 lb (110 kg) or two "short-fin" 500 lb (230 kg) bombs in the internal bomb bay as well as two more bombs under the wings. From early 1944, Coastal Command operated Mk VIs armed with eight 60 lb (27 kg) rockets to carry out anti-shipping strikes.

Other fighter-bomber variants were the Mosquito FB Mk XVIII (sometimes known as the Tsetse) of which 27 were made by converting Mk VIs. These were fitted with a Molins 57 mm cannon, a 6 pounder anti-tank gun modified with an auto-loader to allow both semi- or fully-automatic fire, in the nose, along with two .303 in (7.7 mm) sighting machine guns. The Air Ministry initially suspected that this variant would not work, but mock tests proved otherwise. Although the gun provided the Mosquito with yet more anti-shipping firepower to pit against U-boats, it required a steady and vulnerable approach-run to aim and fire the gun, thus making rockets more effective, especially because Mosquitos without the 6 pounder didn't suffer the weight penalty of the gun. The FB Mk 26 and FB Mk 40, based on the Mk VI, were built in Canada and Australia and were powered by Packard-built Merlin engines.

All the fighter variants shared a number of common features. They had a flat, single-piece armoured windscreen and the pilot was provided with a fighter-style control stick rather than a wheel. The guns in the nose also meant that the bomber variants' entry hatch in the nose had to be relocated to a door on the starboard side, forward of the leading edge.

Training aircraft

The Mosquito was also built as a trainer.

• Mosquito T Mk III : Two-seat training version. Powered by two Rolls-Royce Merlin 21 piston engines. 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.

Canadian-built aircraft

• Mosquito B Mk VII : Canadian version based on the Mosquito B Mk V bomber aircraft. Powered by two 1,418-hp (1,057-kW) Packard Merlin 31 piston engines, 25 built.
• Mosquito B Mk XX : Canadian version of the Mosquito B Mk IV bomber aircraft, 145 built, of which 40 were converted into F-8 photo-reconnaissance aircraft for the USAAF.
• Mosquito FB Mk 21 : Canadian version of the Mosquito FB Mk VI fighter-bomber aircraft. Powered by two 1,460-hp (1,089-kW) Rolls-Royce Merlin 31 piston engines, three built.
• Mosquito T Mk 22 : Canadian version of the Mosquito T Mk III training aircraft.
• Mosquito B Mk 23 : Unbuilt bomber version.
• Mosquito FB Mk 24 : Canadian fighter-bomber version. Powered by two 1,620-hp (1208-kW) Rolls-Royce Merlin 301 piston engines, two built.
• Mosquito B Mk 25 : Improved version of the Mosquito B Mk XX Bomber aircraft. Powered by two 1,620-hp (1,208-kW) Packard Merlin 225 piston engines, 400 built.
• Mosquito FB Mk 26 : Improved version of the Mosquito FB Mk 21 fighter-bomber aircraft. Powered by two 1,620-hp (1,208-kW) Packard Merlin 225 piston engines, 338 built.
• Mosquito T Mk 27 : Canadian-built training aircraft.
• Mosquito T Mk 29 : A number of FB Mk 26 fighters were converted into T Mk 29 trainers.

Torpedo reconnaissance fighter aircraft

To meet specification N.15/44 for Royal Navy use, de Havilland produced a carrier-borne variant. This resulted in 50 Sea Mosquito TR Mk 33s which featured folding wings, a thimble nose radome and fuselage hardpoints for mounting torpedoes. These were followed by 14 Sea Mosquito TR Mk 37s, which differed in having ASV Mk. XIII radar instead of the TR.33's AN/APS-6.

Target tug aircraft

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, finally being retired in 1956.

Australian-built aircraft

• Mosquito FB Mk 40 : Two-seat fighter-bomber version for the RAAF. Powered by two 1,460-hp (1,089-kW) Roll-Royce Merlin 31 piston engines. A total of 178 built in Australia.
• Mosquito PR Mk 40 : This designation was given to six FB Mk 40s, which were converted into photo-reconnaissance aircraft.
• Mosquito FB Mk 41 : Two-seat fighter-bomber version for the RAAF. A total of 11 built in Australia.
• Mosquito PR Mk 41 : Two-seat photo-survey version for the RAAF. A total of 17 built in Australia.
• Mosquito FB Mk 42 : Two-seat fighter-bomber version. Powered by two Rolls-Royce Merlin 69 piston engines. One FB Mk 40 aircraft was converted into a Mosquito FB Mk 42.
• Mosquito T Mk 43 : Two-seat training version for the RAAF. A total of 11 FB Mk 40s were converted into Mosquito T Mk 43s.

Numbers produced

Total Mosquito production was 7,781 of which 6,710 were built during the war. De Havilland accounted for 5,007 aircraft built in three factories in the United Kingdom. Mosquitos were also built by Airspeed Ltd, Percival Aircraft Company and Standard Motors. The Canadian and Australian arms of de Havilland produced 1,134 and 212 aircraft respectively. The ferry operation of the Mosquito from Canada to the war front was problematic, as a small fraction of the aircraft would mysteriously disappear over the 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, it was unclear as to the actual cause of the losses. 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 were delivered successfully by the Canadian operation.

The last Mosquito was completed in November 1950; an NF Mk 38 built at Broughton near Chester.

Survivors

There are believed to be around 30 preserved examples at various collections including the Royal Air Force Museum at Hendon and another (KB336) at the Canadian Aviation Museum in Ottawa. The wooden construction makes restoration difficult.

As of 2004, the original prototype, serial number W4050, was undergoing complete restoration in the de Havilland Aircraft Heritage Centre in Hertfordshire, UK. A restored example is currently on display in the World War II gallery at the National Museum of the United States Air Force. This Mosquito is a British-built B Mk 35 manufactured in 1946, later converted for target-towing, and is similar to the PR Mk XVIs used by the AAF. Having been flown to the Museum in February 1985, suffering several breakdowns along the way and taking many months to arrive, this aircraft has now been restored to a Mk XVI configuration and painted to represent a weather reconnaissance aircraft of the 653rd Bomb Squadron, 25th Bomb Group, based in England in 1944-1945.

Another Mosquito is currently under restoration, involving the fabrication of new fuselage sections by volunteers at the Royal Australian Air Force Museum in Point Cook, Victoria, Australia. Given the poor state of the aircraft when obtained and the nature of the aircraft's fabrication, along with money and labour issues at the museum, it is estimated that it will be in excess of ten years before this Mosquito is complete.

The last Mosquito known to be airworthy (serial number RR299), a T Mk III built sometime between October 1944 and July 1945, crashed on 21 July 1996 with the loss of both crew after stalling during a banked turn at an airshow at the Barton Aerodrome near Barton, Greater Manchester.

Several potential restorations to airworthiness exist. A flying replica using new wood but otherwise original parts is under construction in New Zealand. Another in New Zealand, KA114, is being restored for American collector Jerry Yagen by Avspecs, and it is highly likely that this will become the first airworthy Mosquito since 1996. The Mosquito B 35 held in the Experimental Aircraft Association, Oshkosh, Wisconsin, USA was airworthy when owner Kermit Weeks loaned it to the museum.

The Canadian Historical Aircraft Association (CHAA) based in Windsor, Ontario is building a Mosquito from scratch. They have two unused engines still in the crates and some parts retrieved from a crash in the Arctic.

Glyn Powell located in Papakura, New Zealand has built a mould for the wooden fuselage, and CHAA bought the very first fuselage ever sold. Glynn has also supplied a fuselage to Avspecs as well as the main wing which was delivered in October 2007.

In Vancouver B.C., Mosquito VR796 (CF-HML) is currently under restoration at the Vancouver South Airport area. This is an ex-Spartan Air Services Aircraft and is a postwar B Mk35. It is in excellent condition and not far from becoming airworthy.

Operators

Specifications (DH.98 Mosquito B Mk XVI)

Data from Jane's Fighting Aircraft of World War II and World War II Warbirds

General characteristics

• Crew: 2: pilot, bombardier/navigator
• Length: 44 ft 6 in (13.57 m)
• Wingspan: 54 ft 2 in (16.52 m)
• Height: 17 ft 5 in (5.3 m)
• Wing area: 454 ft² (42.18 m²)
• Empty weight: 14,300 lb (6,490 kg)
• Loaded weight: 18,100 lb (8,210 kg)
• Max. takeoff weight: 25,000 lb (11,000 kg)
• Powerplant: 2 × Rolls-Royce Merlin 76/77 (left/right) liquid-cooled V12 engine, 1,710 hp (1,280 kW) each

Performance

• Maximum speed: 361 knots (415 mph, 668 km/h) at 28,000 ft (8,500 m)
• Range: 1,300 nm (1,500 mi, 2,400 km) with full weapons load
• Service ceiling: 37,000 ft (11,000 m)
• Rate of climb: 2,850 ft/min (14.5 m/s)
• Wing loading: 39.9 lb/ft² (195 kg/m²)
• Power/mass: 0.189 hp/lb (311 W/kg)

Armament

• Bombs: 4,000 lb (1 800 kg)

Avionics

• GEE radio-navigation