JMB1943 Posted 29 May , 2020 Share Posted 29 May , 2020 This is not a question about relative merits of British & German artillery fire. I have a grandfather who served in 228th Siege Battery, RGA; this unit was variously equipped with 8" and 6" howitzers. All things being equal, how far apart were the field-pieces of any given battery separated? My initial assumption is that any particular gun would be distanced far enough from its neighbour to be outside the beaten zone of the German gun-battery. My second assumption is that this German beaten zone is approx. the same as that of the RA. Can anyone provide numbers for accuracy, e.g., figure of merit / beaten zone / zone with 50% of shells etc, for the field-pieces mentioned in the title? Regards, JMB Link to comment Share on other sites More sharing options...
JMB1943 Posted 1 June , 2020 Author Share Posted 1 June , 2020 I have eventually tracked down some real numbers related to the accuracy of British heavy ordnance, as shown in the Table. These data are for an 8" B.L., Mk IV, elevation: 5 deg. 36 min; muzzle velocity: 2045 ft/sec. *Text Book of Gunnery, Maj. G. Mackinlay, RA; London (1887), p.170 Number Of round Range (yds) Difference From Mean Deviation Right (yds) Difference From Mean 1 4968 22.8 24.4 3.0 2 4954 8.8 21.6 0.2 3 4962 16.8 22.8 1.4 4 4908 37.2 20.0 1.4 5 4934 11.2 18.4 3.0 Sum 24726 96.8 107.2 9.0 Mean 4945.2 19.4 21.4 1.8 The mean longitudinal (range) error is 19.4 yds & the mean lateral (deviation) error is 1.8 yds. It turns out that 50% of shots are expected to land within 1.69 x the given error. This length zone is then 1.69 x 19.4 = 33 yds, so these shots are contained in a distance (33/2 yds) i.e. 16.5 yds ahead of and behind the target. Similarly, the breadth zone is 1.69 x 1.8 = 3 yds. The length zone and the breadth zone are at right angles to each other; if they are superimposed, a rectangle is formed which will contain 50% of 50% (i.e. 25%) impacts. Apparently, at the time this was known as the 25% probable rectangle. "The relative accuracy of different guns at different ranges is estimated by the dimensions of this rectangle."* The practical effect of this is, that this 8" gun will strike a wall of 12 ft x 12 ft only 30 shots out of 100, at an accurately known range of 4945 yds. Regards, JMB Link to comment Share on other sites More sharing options...
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