de Havilland Mosquito

During late 1938 de Havilland set about designing an aircraft that could be used for either reconnaissance or as a bomber. The concept of the aircraft was that it wouldn't require defensive armament as its speed and altitude would protect it from enemy defences. It was intended for this new aircraft, designation DH.98, to be built using wood and powered by a pair of Rolls-Royce Merlins. After submitting their design little interest was shown by the Air Ministry and the project was put on hold.

With the break out of war in September 1939 and the German U-boats proving a constant threat to British shipping and the light alloy imports required for aircraft production, the idea of an all wooden aircraft was intriguing for the Air Ministry in case of a light allow shortage. So the go-ahead was given to de Havilland to begin detailed design and during December 1939 this began, followed three months later on the 1st March 1940 by an order for a prototype and 50 production examples. This was placed under Specification B.1/40 which was written specially for this aircraft.

With the Allied evacuation from Dunkirk, France a couple of months later and the upcoming Battle of Britain (10th July 1940 - 31st October 1940) requiring production to be focused on current aircraft types, in particular fighters, the DH.98 project was officially put on hold. de Havilland though told his team to keep working on the project which was officially restarted a couple of months later. The Mosquito would be built mainly of plywood and balsa wood. This made the aircraft lighter and also easier to repair any battle damage. Construction of the type saw each half built and fitted before both sections were put together. Crew would consist of a pilot and navigator sat side-by-side.

The first of the three prototypes to fly was a Mk I, intended as an unarmed bomber, which was ready for its maiden flight to take place on the 25th November 1940. Flying from Hatfield with Geoffrey de Havilland Jr at the controls this first flight and further flights showed that the aircraft had enormous potential. With a top speed of 382 mph, thanks to a pair of 1,460-hp Rolls-Royce Merlin 21 engines, a range of over 2,000 miles and able to reach 35,000 ft. The following month on the 29th December 1940 the prototype was demonstrated to the Air Ministry and as a result 150 were ordered of the now nicknamed 'Wooden Wonder'.

The following year on the 19th February 1941 the Mosquito started to undergo the customary trials at the Aeroplane and Armament Experimental Establishment at Boscombe Down. Five months later priority production began on the 1st July 1941. In between the trials and production beginning the two other prototypes flew. The second on the 15th May 1941 and was the fighter version. Its armament consisted of eight guns mounted in rows of four. The top row was four 0.303-in machine-guns whilst the bottom row was four 20mm cannons. The third prototype was the photo reconnaissance version which had longer wings and no armament.

With a top speed of 382 mph and power supplied by two 1,460-hp Rolls-Royce Merlin 21 engines and a range of 2,180 miles, it was the Mosquito PR.Mk I variant which was the first of the type to enter service when on the 13th July 1941 No. 1 Photographic Reconnaissance Unit based at RAF Benson received the first aircraft. It was also the first of the type to enter operational service when on the 17th September 1941 a sole example performed reconnaissance over Brest, La Pallice and Bordeaux, France during the day. This would see the high speed of the aircraft as a way of defending itself instead of armament put to the test when three Messerschmitt Bf 109s were sent to intercept the Mosquito, a test it passed as they failed to do so.

The Mosquito B.Mk IV bomber variant was the next to enter service, with the first production example flying on the 8th September 1941. Able to carry four 500lb bombs over a range of 2,040 miles its pair of 1,460-hp Merlin 21s gave it a top speed of 374 mph. These would initially be available in November 1941 when No. 105 Squadron stationed at RAF Swanton Morley had their Bristol Blenheim Mk IVs replaced. They would spend the next few months familiarising themselves with the aircraft and working out tactics. Their first sortie with the type saw four raid Cologne, Germany on the 31st May 1942 with all returning back to base.

Four months later another four Mosquitos from No. 105 Squadron attacked the Norwegian headquarters of the Gestapo in Oslo at low-level on the 25th September 1942 with the following day seeing the type revealed to the British public. This wouldn't be the last low-level nuisance raid carried out by the squadron. Another such raid on the 30th January 1943 saw a radio speech by Herman Goring interrupted when the broadcasting station in Berlin, Germany was attacked.

The last of the prototype variants was the fighter version which would enter service as a night fighter known as the Mosquito NF.Mk II. Like the Mosquito PR.Mk I and Mosquito B.Mk IV this was also powered by the 1,460-hp Rolls-Royce Merlin 21 but had a top speed of 366 mph with a range of 1,705 miles. Armament consisted of four 20-mm cannons and four 0.303-in machine-guns and was fitted with Mk IV Airborne Interception radar. It would be during January 1942 with No. 157 Squadron based at RAF Castle Camps, which had been reformed the previous month, that this variant would first be delivered to. Three months later saw the squadron use the Mosquito NF.Mk II for its first night operations on the 27th April 1942.

To help crews convert to the Mosquito a trainer would be produced. Featuring dual controls and its armament was removed. The prototype would be a converted Mosquito NF.Mk II and this made its first flight on the 30th January 1942 and could reach a top speed of 384 mph, the first of the Mosquito T.Mk IIIs would enter service during August 1942.

The most produced Mosquito variant was the FB.Mk VI which was a fighter-bomber powered by either the 1,460-hp Rolls-Royce Merlin 21 or Merlin 23 giving the aircraft a top speed of 380 mph, it had a range of 1,205 miles. Armament would consist of four 20mm cannons and four 0.303-in machine-guns and either four 500lb bombs or from 1944 eight rocket projectiles and two 500lb bombs. The prototype made its maiden flight on the 1st June 1942 and entered service the following year on the 11th May 1943 when No. 418 Squadron, Royal Canadian Air Force had their Douglas Boston Mk IIIs replaced. The Mosquito FB.Mk VI would equip over 20 squadrons serving over Europe and it would also see action in the Far East.

It was to be a modified Mosquito FB.Mk VI, which had been strengthened and had an arrestor hook fitted, that had the distinction of becoming the first twin-engined British aircraft to land on an aircraft carrier when on the 25th March 1944 Captain Eric 'Winkle' Brown achieved the feat aboard HMS Indefatigable (R10). This in turn would lead to the Sea Mosquito.

Due to the Mosquito's ability to perform precision strikes it was chosen for Operation Jericho. Taking place on the 18th February 1944 this saw nineteen Mosquito FB.Mk VIs, comprised from Nos. 21, 464 and 487 Squadron, escorted by fourteen Hawker Typhoons attack Amiens prison in France with the intention of releasing resistance and political prisoners by breaching the prison wall. Whilst the wall was breached 102 prisoners were killed, 258 escaped but most were recaptured. Two Typhoons and Two Mosquitos were shot down and of the six airmen four were killed in action, including Group Captain Percy Charles Pickard, and two taken prisoner of war.

The Mosquito was also earmarked for use to carry a Barnes Wallis designed bouncing bomb given the codename “Highball”. The idea being that it would be used to attack the capital ships of the German Navy. This would lead to the formation on the 1st April 1943 of No. 618 Squadron who would spend a year in training, however in the end their intended target had moved and “Highball” would not be used.

Another role that the Mosquito performed was that of a Pathfinder. This would see the Mosquito fly ahead of the main bomber force dropping different coloured flares over the target with the help of the Oboe targeting system. Other duties for the Pathfinder Mosquitos saw them carry out bombing raids and drop 'Window'. This was designed to mimic a bomber stream on a radar screen. The Mosquito Pathfinder Force helped to improve the accuracy of bombing.

The de Havilland Mosquito continued to serve with the Royal Air Force post-war. The bomber variants were replaced by the English Electric Canberra during the 1950s, so it was a Mosquito PR.34A of No. 81 Squadron that would fly the last operational mission of the type. This occurred on the 15th December 1955, although a number of Mosquitos would serve as target tugs until 1963.

An extremely versatile aircraft over 35 variants were built and it would serve with a number of air forces including the United States Army Air Force and the Royal New Zealand Air Force. In total 7,781 Mosquitos were built in the UK, Canada and Australia, with the first Australian example, known as the Mosquito FB.Mk 40, making its maiden flight on the 23rd July 1943, with the 15th November 1950 seeing the last production version built, a Mosquito NF.Mk 38.