Adrodd fel Amhriodol
Testun Gwreiddiol (Anodiad: EAW039859 / 1326851)
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Velocity screen masts, the shorter pair were 110 feet tall, the other pair were 210 feet tall. The distance between the two sets was 79 metres. Between each pair of masts a square frame of about 6 to 8 feet per side (my own very rough estimation from photo on page 55 of English Heritage Report 39-2013) was suspended, precisely aligned with the gun that was being tested. When fired, the shell would pass through each frame which was covered with a fine metal mesh. The time between the first and second mesh being perforated was measured and from this the velocity of the shell at firing could be calculated. (I assume that the time of impact on Maplin sands was also measured so that average and terminal velocities could also be calculated.)
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