de Havilland Mosquito Prototype (W4050)

de Havilland Mosquito Prototype (W4050)  [@ de Havilland Aircraft Heritage Centre]

de Havilland Mosquito Prototype (W4050)Built at Salisbury Hall, W4050 was dismantled and moved to Hatfield by road on 3rd November 1940, just over a year after the Mosquito design team moved to Salisbury hall from nearby Hatfield.   The aircraft was painted overall yellow for easy identification and carried the class B markings E0234.   After reassembly, initial engine tests were performed on 19th November; the first taxiing tests five days later.   Geoffrey de Havilland Jnr., with John E.  Walker as observer, flew W4050 for the first time at 3.45pm on the 25th November.

Following 35 hours of initial trials at Hatfield, the aircraft, by now officially adopted as W4050, was delivered to Boscombe Down on 19th February 1941 with camouflaged top surfaces and prototype markings for official service trials.  Alan Wheeler was the first test pilot at Boscombe Down to fly W4050. 

Following a ground accident on 24th February in which the tail wheel caught in a rut fracturing the fuselage just aft of the wing trailing edge, the decision was made by Fred Plumb, de Havilland's Chief Engineer, to replace the fuselage with one built for W4051, the Photo Reconnaissance prototype. 

On completion of the change, W4050 was flown back to Hatfield for some adjustments on 14th March, returning to Boscombe Down four days later with extended engine nacelles fitted for handling trials. 

On the aircraft's 100th flight on 4th May, a maximum level speed of 392 mph was achieved at 22,000 ft with an all-up weight of 16,000 lb.  During further handling tests at Boscombe Down, the fuselage was fractured again in a heavy landing.  This time the damage was repaired with an irregular patch on the port fuselage side just behind the wing trailing edge that is still visible today.

Service trials were completed on the prototype on 23rd May 1941, to be continued on more representative production aircraft.  On return to Hatfield, the prototype was used by de Havilland for a variety of tests in a number of configurations including stall tests, the effects of flying with the bomb doors open and with a mock-up turret fitted immediately behind the cockpit.

de Havilland Mosquito Prototype (W4050)

de Havilland Mosquito Prototype (W4050)  [@ de Havilland Aircraft Heritage Centre]

In late October 1941 W4050 was temporarily grounded for the fitting of more powerful Merlin 61 engines, eventually flying in this form on 20th June 1942 and attaining an altitude of 40,000 ft on its second flight.  Merlin 77s were then fitted with flight trials recommencing on 8th October, and a top speed of 439 mph was achieved in November, the highest by any Mosquito.  Development flying of the prototype reduced during 1943, but it did spend a short period with Rolls Royce from 1st March until 10th June. 

In 1944 the prototype was grounded and allocated to de Havilland apprentice ground training.  W4050 took part in the filming of 'The Mosquito Story' in 1945, the film made by de Havilland on the development, production and use of the Mosquito, following which it moved back to Salisbury Hall for use by the de Havilland Aeronautical School in 1946.  W4050 appeared in the SBAC displays at Radlett in 1946 and 1947, surrounded by a selection of the typical weapon loads. 

W4050 was declared Category E and struck off charge on 21st June 1947. 

W.J.S.  (Bill) Baird, the Assistant Public Relations Manager at Hatfield, had become aware of the historical significance of the prototype Mosquito as early as 1945.  When the aircraft was ordered  to be destroyed he saved it from being burned, having it dismantled and then moving it first to Panshanger, then Hatfield for a short time, to the factory at Chester and finally back to off airfield storage at Hatfield. 

In the meantime, Walter J.  Goldsmith, a retired Army Officer, had bought Salisbury Hall and upon realising that it was the birthplace of the Mosquito asked whether W4050 could go on display in the grounds.  Thus a permanent home was found back at Salisbury Hall, where it was put on public display on 15 May 1959.