Beyond the "Warwick" of 1939, the Vickers concern failed to net much interest from the Royal Air Force (RAF) in another heavy bomber design during World War 2 (1939-1945). In seeking a successor for its "Wellington" medium bomber series, company engineers went to work on an attempt to fulfill Air Ministry Specification B.11/41, this product intended as a twin-engine, high-speed medium bomber. However, this design did not live up to its proposed expectation so a four-engined form was drawn up in its place and the same "geodesic" construction practice used on earlier Vickers large aircraft was to be employed - the process incorporating a "basket-weave" type understructure covered over in fabric to produce a lightweight-yet-strong body.
As the same time, company engineers were attempting to develop a Wellington bomber with pressurized cabin spaces for the crew operating at high altitudes and Air Ministry authorities pushed for such a feature on the existing Warwick. Added to this was a new elliptical wing mainplane now carrying two engines apiece - for a total of 4 x Rolls-Royce "Merlins" - with the project goal becoming a heavy bomber exhibiting a 55,500lb Maximum Take-Off Weight (MTOW) and capable of a warload of 8 x 1,000lb conventional drop bombs, a service ceiling nearing 43,000 feet and a maximum speed of 350 miles per hour.
Two prototypes were covered by Specification B.5/41 and work on the airframes spanned into late-1942 by which point the original Wellington successor design was merged into the program under Specification B.3/42 and this commitment ultimately begat the "Windsor" (Type 447) high-altitude heavy bomber - the first-form of the aircraft recognized as "Windsor B.Mk I" before the end of 1943.
The original defensive armament suite of 1942 involved 2 x 7.7mm machine guns in fixed, forward firing mounts at the nose with 2 x 20mm cannons fitted to a rear turret. For 1943, the rear turret was dropped from contention and was succeeded by a pair of remote-controlled turret barbettes, each armed through 2 x 20mm cannons, now fitted to the aft-sections of the outboard engine nacelles. In April 1944, waist gun positions were added to further broaden the defensive network protecting the aircraft.
Three total Windsor prototypes were ultimately built and completed. The first to fly was the gun-less DW506 (Type 447) testbed on October 23rd, 1943 with Rolls-Royce Merlin 65 series engines of 1,315 horsepower each installed. Subsequent testing revealed a sound, large aircraft with good characteristics for a bomber though the design was far from finalized and ready for serial production as it flew underweight with little to no mission-equipment installed. DW506 was eventually written-off following a crash-landing on March 2nd, 1944 - the bomber sliding off the runway and the main part of the fuselage damaged beyond repair.
On February 10th, 1944, prototype DW512 (Type 457) first took to the air with some of its critical mission equipment in place though it still lacked its defensive gun suite. This model was powered by Rolls-Royce Merlin 85 series engines of 1,635 horsepower each (driving four-bladed propellers) and closer matched the intended production form than its predecessor. Testing of this article soon revealed a ballooning effect of the special fabric skin (a defect first witnessed on prototype DW506) so a new skin formula was drawn up and applied.
The third prototype became NK136 (Type 461) and this carried the same engine fit as DW512 but installed the intended armament suite of 4 x 20mm cannons in their remote-controlled, nacelle-mounted turret barbettes. A first-flight of this aircraft was had on July 11th, 1944 and firing trials spanned into June of 1945 by which point the war in Europe had ended.
With the war over in full by September 1945 (the Japanese surrender in the Pacific), the Windsor program was cancelled during November as its need was no longer apparent. The continued evolution of the Avro Lancaster heavy bomber also added to the notion that the Windsor would become a bloated, costly large aircraft for the long term and the war-proven Lancaster essentially was able to handle nearly any mission role given to it.
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Vickers-Armstrongs Ltd - United Kingdom Manufacturer(s)
2 x 7.7mm machine guns in fixed, forward firing nose position.
2 x 20mm cannons in aft turret emplacement.
UPDATED (only fitted to third prototype):
2 x 7.7mm machine guns in fixed, forward firing nose position.
2 x 20mm remote-controlled cannons in portside outboard engine nacelle (aft-facing).
2 x 20mm remote-controlled cannons in starboard side engine nacelle (aft-facing).
Up to 8,000lb of internally-held conventional drop ordnance (later estimate increased to 12,000lb warload).
Windsor - Base Series Name; three prototypes completed.
Type 447 - Original prototype; fitted with 4 x Rolls-Royce Merlin 65 engines of 1,315 horsepower each; article lost after crash landing.
Type 457 - Modified prototype with Merlin 85 engines of 1,635 horsepower each; fuselage armoring; various changes implemented.
Type 461 - Melin 85 engines; fitted with proposed armament suite.
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