History[]
Built at Chester, BJ895 was delivered to Vickers at Weybridge on 12 August 1942,[1] for conversion to carry prototype bouncing bombs.[N 3] The modifications consisted of an hydraulic power system, in place of the original electric, to spin the bombs, fitment of an radio altimeter and installation, in the bomb aimer's position, of a clear perspex ventral blister to improve vision downwards and toward the rear. The modifications were originally intended to include a pair of cine cameras, one pointing downwards to record the initial bounces of the bomb, and one in the cockpit to record the readings on the flight instruments, but for some reason, these were never fitted.
Modification of the aircraft was completed by 23 September, when Vickers' chief test pilot 'Mutt' Summers took BJ895 up for a 25 min air test, with authority for application of the /G marking for the serial number being received the next day. This led to the test spheres being mounted in the Wellington, where they were first spun on 23 October.[1]
Notes[]
- ↑ The /G suffix on the end of the serial indicated the aircraft was fitted with secret equipment - in this case the bouncing bomb system - and needed to be kept under armed guard when not being flown.
- ↑ The original footage shows the Wellington flying from right to left, and details of the bomb are clearly visible. The version in the film shows the Wellington flying from left to right, and the bomb is covered by a black blob, which was painted on frame by frame to hide the weapon, as this was still secret during filming.
- ↑ Officials originally allocated a Mk Ic on 20 July for use in the tests. This prompted Tommy Lucke, the assistant test pilot at Vickers, to point out that, in order to reach the required release speed of 300 mph IAS, a Mk Ic would need to dive at 40 degrees from 9,000 ft, pulling out at a sink rate of 1,000ft to 1,500ft, before trying to level out at 300 ft, a move that pilots would refuse to carry out so close to the water. In contrast a Mk III could reach 300 mph IAS at 300 ft after a shallow dive from 2,500 ft. Lucke's argument led to the allocation being changed to a Mk III on 1 August.[2]