De HAVILLAND MOSQUITO STARBOARD ENGINE OUTER EXHAUST STUB

Even before the outbreak of WWII, the De Havilland aircraft group had already established an enviable reputation for the design and production of innovative, high speed aircraft.

In the early 1930s they had won numerous international air speed records with their DH.88 Comet racer and had later, pioneered the production of composite wood construction aircraft such as the DH.91 Albatross 22 seater airliner.

In September 1936, the British Air Ministry had issued the request for a twin - engined medium bomber that could carry a 3,000lb bomb load and attain a maximum speed of 275mph.

Aviation manufacturers were quick to provide submissions entering heavy designs with new high-powered engines and multiple defensive gun turrets such as the Avro Manchester and Handley Page Halifax.

To everyones surprise, De Havilland submitted plans for a fast unarmed bomber which could cruise at a speed of 300 mph whilst still being able to carry the requested 3000 lb bomb load.

De Havilland’s designer, George Volkert also advocated an all laminated wooden construction which, coincidently addressed one of the Air Ministry’s concerns in regard to the use of non-strategic materials for aircraft production.

Volkert argued that an aerodynamically clean, low profile wooden construction, coupled with two powerful engines would create an aircraft that would be invulnerable to slower enemy fighters and as a result, would not require heavy defensive armament. In fact he argued, given the appropriate power plants, the aircraft would likely well exceed the Air Ministry’s speed requirements.

After significant experimentation for existing power plants of the day, the first Mosquito prototype (W4050) took to the air powered by Two Merlin 21 two-speed, single-stage supercharged engines , driving three-bladed de Havilland Hydromatic constant-speed controllable-pitch propellers.

During its trials on 16 January 1941, W4050 outpaced a Spitfire at 6,000 ft. 

Original estimates had calculated that, as the Mosquito had twice the surface area and over twice the weight of the Spitfire Mk.II, but also had twice its power, the Mosquito would be 20 mph faster. Over the next few months, W4050 surpassed this estimate, easily beating the Spitfire Mk.II in tests, reaching a top speed of 392 mph at 22,000 ft (6,700 m), compared to a top speed of 360 mph for the Spitfire.

Whilst the Mosquito's design was praised for its light and effective control surfaces which provided good manoeuvrability, those same features also required that the rudder not be used aggressively at high speeds. 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 200 mph, and rpm set to 2,650. The speed could be reduced to an acceptable 150 mph for low-speed flying.

The Mosquito had a high stalling speed of 120 mph with undercarriage and flaps raised. When both were lowered, the stalling speed decreased from 120 to 100 mph. Stall speed at normal approach angle and conditions was 100 to 110 mph.

This decrease in stall speed resulted in the Mosquito requiring a much higher landing speed - something many RAF and USAAF pilots found somewhat daunting having been used to controlling aircraft that could be 'floated' onto the runway by the use of wing flap flaring and a much slower approach speed. 

Early on in the Mosquito's operational life, the intake shrouds that were to cool the exhausts on production aircraft overheated. 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 10 to 13 mph.

On 15 November 1941, 105 Squadron, RAF, took delivery at RAF Swanton Morley, Norfolk, of the first operational Mosquito Mk. B.IV bomber, serial no. W4064.

These were powered by two, single-stage two-speed, 1,460 hp Merlin 21s or 1,635 hp Merlin 25s but during its operational life, the Mosquito underwent a number of power plant upgrades with the final PR Mk 34A high altitude photo reconnaissance version featuring two super charged 1,690 hp Merlin 114 engines.

The fighter, night fighter and ground attack versions also sported four poweful 20 mm nose cannons.

Throughout 1942, 105 Squadron, undertook daylight low-level and shallow dive attacks.

Apart from raids on Oslo and Berlin, the strikes were mainly on industrial and infrastructure targets in occupied Netherlands and Norway, France and northern and western Germany.

Mosquito crews faced deadly flak and fighters, particularly from the Luftwaffe’s new Focke-Wulf Fw 190s,. Germany still controlled continental airspace and the Fw 190s were often already airborne and at an advantageous altitude. Collisions within the formations also caused casualties. It was the Mosquito's excellent handling capabilities, rather than pure speed, that facilitated successful evasions.

Over the course of its operational life, the De Havilland Mosquito underwent numerous modifications and role adaptions from general, fast low level strike aircraft, to radar equiped night fighter; photo reconnaissance and marine torpedo bomber.

One of its most significant roles - that of bomber pathfinder was its ability to pass over targets well ahead of the bomber fleet and mark the target area with high incendiary flares and munitions for the heavy bombers to release their ordinance on.

Over 7,780 Mosquitoes were manufactured during the course of the war but barely a handful survive to this day and even less in operational flight condition.

This was largely to its all laminated all-wooden construction with glues and fabrics breaking down over the years.

Salvaged from a badly damaged operational De Havilland Mosquito, this Starboard Outer Engine Merlin Exhaust Stub represents an incredibly rare piece of WWII aviation history from one of the most iconic RAF fighter/bombers of the period.

Standing at 340 mm high and mounted in its 100yr old, hand-crafted Mango Wood display stand with engraved plaque and highly detailed scale model of a de Havilland Mosquito perched atop its magnetic display arm, plus a detailed laminated Fact Sheet featuring a photo of the instrument in the Mosquito's cockpit, this Recovery Curios Aircraft Collectable would make a perfect gift for the pilot or aviation enthusiast in your life.

This De Havilland Mosquito Instrument comes complete with detailed 1/72 or super detailed 1/48 Scale Model, Mango Wood Stand & Plaque plus Printed Fact Sheet featuring photo of instrument in aircraft cockpit.

Return to De Havilland Mosquito MAIN PAGE