De Havilland Mosquito PR Mk I

The PR Mk I was the first model of the Mosquito to see active service. The original order for fifty Mosquitoes of March 1940 had been altered to one that included 19 unarmed photo reconnaissance aircraft. On 21 July 1941 that order was changed again, when nine of the PR Mossies were diverted to become bombers (B Mk IV Series I). This left ten PR Mk Is (including the prototype, Mosquito W4051).

The W4051 first flew on 10 June 1941, significantly later that first expected, after its first fuselage was used to repair the first Mosquito prototype (W4050) after it suffered a crash.

W4051 had the same short engine nacelles as the W4050, although its wings were 20in longer. It was powered by the 1,460 hp Merlin 21 engine. The PR Mosquitoes used the same transparent nose as the bomber variants, as well as the entry hatch under the cockpit.

It carried up to four cameras – one oblique and three vertical – with a wide variety of different combinations of cameras being used depending on the mission. Often two of the vertical cameras were tied together to form a single “split” camera where two identical cameras would point at slightly different but overlapping areas. The resulting photos would provide stereoscopic coverage of the overlapping area as well as normal coverage of the extra areas.

The main user of the Mosquito PR.Mk I was No 1 PRU (Photographic Reconnaissance Unit), based at Benson. It received the first Mosquito to enter RAF service on 13 July 1941. This was the W4051 prototype, which as a result of its delayed construction was considered combat ready. Eventually the unit received all ten of the PR.Mk Is.

The PR Mk I quickly began to prove the basic premise behind the Mosquito was correct. On 16 September 1941 during tests over the Bay of Biscay one of their aircraft was intercepted by three Messerschmitt Bf 109s, but escaped without damage. The unarmed Mosquito could indeed use its speed to escape German attack.

17 September saw the first successful Mosquito missions, a daylight reconnaissance flight over Brest, La Pallice and Bordeaux, already established as German naval bases.

The Mosquito PR Mk I had a range of 2,180 miles, top speed of 382mph and ceiling of 35,000 feet. It had the range and speed to photographic targets inside Germany – indeed one early mission reached as far as Poland! The only problem with the PR Mk I was that there were never enough of them.

 Mosquito Photo-Reconnaissance Units of World World 2, Martin Bowman. The third of three books looking at the RAF career of the Mosquito, this volume looks at the career of the Mosquito as a unarmed photo-reconnaissance aircraft, relying on its exceptional speed to keep it safe. [see more]
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How to cite this article: Rickard, J (15 April 2007), De Havilland Mosquito PR Mk I,

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