Testing the Vickers Windsor Prototypes: A Chronological Account
Detailed account of the testing program for the Vickers Windsor prototypes, highlighting the challenges encountered and modifications implemented.
Prototype One (DW506): Aerodynamic Focus (Type 447)
- Initial Flight and Assessment: The first Windsor prototype (DW506) took flight from Farnborough on October 23, 1943. The initial flights aimed to assess its aerodynamic characteristics, with ballast substituting for armament and bomb gear. The aircraft handled well, even at increased weights. Early performance showed a speed of 302 mph at 25,000 feet with a takeoff weight of 46,000 pounds.
- Premature End: After accumulating 33 hours and 45 minutes of flight time, DW506 experienced a propeller failure on March 2, 1944, leading to a forced landing that damaged the airframe beyond repair. This incident cut short the testing program for the first prototype.
Prototype Two (DW512): Addressing Structural Concerns (Type 457)
- Entering Testing with Modifications: The second prototype (DW512) featured annular engine installations, distinguishing it from its predecessor. It commenced flight testing on February 15, 1944, demonstrating comparable performance to DW506. This prototype was heavier due to armor plating and other modifications.
- Wing Fabric Deformation: Flight testing revealed a significant issue: the fabric covering the wings deformed during flight, particularly during maneuvers involving high G-forces. This problem, also observed to a lesser extent in DW506, severely impacted the aircraft’s stall characteristics.
- Remedies and Further Testing: To address the fabric deformation, modifications included using a glasscloth-backed fabric for the wing covering. Further changes included a new rudder (taken from DW506), a modified tailwheel, and increased tailplane incidence. Following these adjustments, DW512 proved valuable in stability and structural twist assessments, critical for evaluating the remotely controlled barbette system’s effectiveness.
Prototype Three (NK136): Armament and Refined Structure (Types 461/480)
- Structural Improvements: The third prototype, NK136, incorporated a strengthened fuselage with four longerons (compared to three in the earlier prototypes). This change aimed to eliminate tail displacement concerns, particularly relevant given the planned addition of the remotely operated barbettes. The wing covering also saw improvements, with a heavier, wire-mesh-backed fabric intended to mitigate the deformation issues experienced in the previous prototypes.
- Initial Flights and Performance: NK136 first flew on July 11, 1944, initially without the barbette armament. Early performance proved disappointing, with the aircraft about 25 mph slower than expected at recorded altitudes. Despite attempts to improve performance through polishing the aircraft’s surfaces, these efforts yielded minimal improvement.
- Barbette Integration and Trials: The innovative remotely controlled barbettes, each armed with twin 20mm cannons, were eventually installed in NK136. The design, development, and installation of this armament system closely mirrored the process used for similar systems trialed on the Warwick bomber.
- Extensive Firing Trials: Following installation, NK136 underwent comprehensive ground and air firing trials of the barbette system. These trials occurred at various locations, including Pembrey, Angle, and Lyme Bay. The trials assessed different mounting options and the system’s effectiveness at various altitudes and speeds.
Unflown Prototypes and Project Cancellation:
- Two additional prototypes, NN670 (Type 471) and a fourth unnamed prototype, were in various stages of completion when the project was canceled in 1946.
- NN670, intended for production standard, was re-designated as Type 483 and projected to achieve a 4,000-mile range. This prototype was very near completion when canceled.
The testing program of the Windsor prototypes, though ultimately cut short, showcased the complexities of wartime aircraft development. While demonstrating promise in certain areas, the Windsor faced challenges related to structural integrity and performance. The innovative features, notably the remotely controlled barbettes, underwent rigorous testing, but the aircraft’s overall development was ultimately overtaken by the war’s end and the emergence of other capable bombers.