When the Second World War started in 1939 the RAF’s Bomber Command was equipped with three main types that were, technically speaking, their “heavy bombers”; the Handley Page Hampden, the Armstrong Whitworth Whitley and the Vickers Wellington.
Of these aircraft, the Wellington was to prove the most useful. Solid and dependable, the Wellington would be the most produced British bomber of the entire war, being built from 1936 until 1945 and used in a multitude of different roles.
But even before the outbreak of the conflict the RAF were thinking that these designs would soon need replacing with larger aircraft that could carry even greater bombloads over bigger distances. And to accomplish that, these new aircraft would need far more engine power.
Initially plans revolved around twin engine designs, typified by the Avro Manchester and the Vickers Warwick. But though these did get into service, they experienced problems with their powerplants and were also recognized in the light of combat experience as not really meeting the RAF’s growing needs, and so four engine heavy bombers became the standard for that service.
But even as these were coming into service the British authorities wanted design work to start on their replacements, because if there was one lesson being demonstrated during the War, it was just how quickly technology was moving – hence why the Wellington went rapidly from being considered a heavyweight to a medium bomber.
So even as the Lancaster and Halifax heavy bombers began to enter service in the early 1940’s, the British were thinking about their replacement. And while the Wellington was still in full production and highly valued, it was no longer in the premier category and so in 1941 Vickers set about developing a new heavy bomber for the RAF.
This would take shape as the Vickers Windsor.
Initially, this was intended to fulfil a specification for a high-altitude bomber which essentially took the existing Warwick and fitted it with a new wing with four engines; a development path that would have mimicked that of the Avro bombers.
But with the Air Ministry issuing a specification in 1942 for a future replacement for the Stirling, Lancaster and Halifax, Vickers decided to take the work they had done on the new wing and created a fresh fuselage to maximize the aircraft’s potential. This was required to carry a bombload of 8,000lb (3,630kg) and be capable of 350mph (563km/h) at an altitude of 31,000ft (c.9,450m).
Two prototypes were initially ordered, followed by orders for additional prototypes, pre-production aircraft and in April 1943 for three hundred production Windsor B. Mk.1’s.
In design terms the Windsor used the techniques already employed by Vickers. Their line of bomber aircraft, originating with the Wellesley in 1935, were designed by the genius of Barnes Wallis – he of “bouncing bomb” fame.
Wallis had pioneered the geodesic airframe as the construction method for Vickers bombers.
This contrasted with most aircraft construction techniques in that instead of using beams to build the airframe and aircraft skin around, a geodesic design uses a lattice framework of light alloy to create the structure, removing the need for internal beams as the outer basket weave provides the aircraft with its rigidity. This lightens the structure and frees up internal space while also providing great strength and rigidity, as well being tremendously resilient to damage.
The Windsor used the same geodesic methods, including on its huge elliptical wing, which had a span of 117ft 2 inches (35.17m). This was effectively hollow from tip to tip and in the production machines was to hold the main tanks which were expected to carry 16,275 litres (4,300 US Gallons) of fuel.
However, the geodesic design didn’t lend itself to the use of metal skin on an aircraft, and Vickers’ earlier bombers were skinned in doped linen. This wasn’t considered suitable for the higher speeds expected of the Windsor.
The problem for Vickers was that they were geared for geodesic construction and switching to other construction methods would entail a major disruption to their production capability while they retooled and retrained their staff. So, they applied some ingenuity and developed a new flexible skin made of extremely thin steel wires and ribbon woven into a cloth and then doped with PVC.
This provided for an extremely strong skin construction that could withstand the pressures expected of it but was not a simple construction method, apparently requiring the use of a tuning fork to get the stressing correct on application.
But such flexibility and strength was required because the Windsor’s wing construction, not using rigid spars for support, required special thinking and adaption. Wallis therefore designed the outer wings to take up the pressure from the gross weight load by rising after take-off, with the wingtips lifting by more than four feet (1.2m) as the plane left the ground. This apparently took some getting used to by the pilots who did fly the Windsor.
To compensate for this wide tracked loading when on the ground, the Windsor also employed an unusual undercarriage, with each engine nacelle being fitted with a retracting wheel. This did make for a better load distribution, though the pilot did have to be aware of the outer wheel set so as not to catch it or run anything over.
The Windsor’s body was also surprisingly bulky, with very little ground clearance. This was due to recognition that the initial 8,000lb specification was too light a load, especially compared to the bombloads being carried by the aircraft the Windsor was planned to replace, and as a result extra capacity was designed in.
This is an important consideration as regards to geodesic designs as they do not have the ability to undergo major structural changes in contrast to more conventional construction techniques because of the interwoven nature of their structure. As a result, the bulk of the Windsor was expected to provide it with a maximum bombload of 12,000lb (5,443kgs).
On top of the payload, the defensive armament was somewhat unconventional, being composed of two forward firing .303 machine guns in the nose and two barbettes in the rear of the outermost engine nacelles. These would each contain two 20mm cannon and be directed by the rear gunner who had a position in the aircraft’s tail. As it was this was only fitted in the third and, as it turned out final, prototype.
First flight was conducted in October 1943, with this aircraft being fitted with a powerplant of four Rolls Royce Merlin 65 engines that produced 1,315hp each. These was replaced in the next two prototypes by Merlin 85s that produced 1,635hp.
The Windsor reportedly flew extremely well, being very responsive for such a big aircraft and having surprisingly few issues. Top speed achieved was 317mph (510km/h) which while not a as fast as initially specified was an improvement over the current generation of heavy bombers.
Indeed, compared to the Lincoln I that was in development at the time for the same requirement, the Windsor was faster and had longer range with a 12,000lb bombload.
A setback was experienced when the first prototype was lost in a landing accident in March 1944 during testing, an incident that notably broke the aircraft but left the crew unharmed. But such losses are entirely expected and the second and improved prototype was already conducting flights by that point.
In fact, concerns weren’t really with the aircraft’s performance, but mainly in its single-pilot cockpit. This, located high up in the aircraft gave excellent visibility but there were issues that the position was difficult to access in case of the pilot being incapacitated.
Consideration was then given to fitting a more conventional nose layout closer to existing designs, as it was plain by now that the Windsor wouldn’t be seeing action over Germany, but in the Pacific. Here its huge wing capacity raised the prospect of creating a very long-range bomber and Vickers proposed a version that would carry a 4,000Ib (1,814kg) payload with a range of 4,000 miles (6,436km).
Production was expected to get underway in 1945, and the aircraft’s increasing weight led to consideration being given to fitting it with more powerful Griffons and even the new Clyde turboprops that were in development to further boost performance.
But as it was these all stayed on the drawing board. In late 1944 the order for 300 was cut to 100.
Issues with the complicated barbette gun positions were causing concern and the Lincoln, a far simpler design in comparison, was proving much more straight forward in its testing.
With the end of the war in September 1945 there was no need for two main heavy bomber types and in November the Windsor orders were completely cancelled, with the first of the pre-production aircraft in an advanced state of construction. By 1946 the two remaining prototypes were relegated to ground instruction duties and would be scrapped shortly thereafter.
Thus ended the Windsor, the final bomber in a line started by Barnes Wallis in 1935. Because when Vickers built their next bomber just a few years later, the Valiant, it was of a thoroughly modern design.
Sources/Related:
https://www.key.aero/article/failed-vickers-windsor
https://weaponsandwarfare.com/2019/04/15/vickers-armstrongs-447-windsor/
https://www.baesystems.com/en/heritage/vickers-windsor
https://en.wikipedia.org/wiki/Vickers_Windsor
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