The groundwork of practical naval gunnery; a study of the principles and practice of exterior ballistics, as applied to naval gunnery, and of the computation and use of ballistic and range tables . GUX FIEE 427. Let us now suppose that we are going to fire salvos from a l)atterv of 1^guns, for which r = 2900 f. s., w = S70 pounds and 6 = 0.(U. Let us also assume thatwe have a vertical target 30 feet high and wide enough to eliminate the necessity forconsidering lateral deviations due to accidental errors. Let us take the mean errorsof the gun in range, first as 40 yards, next as 60 yards,
The groundwork of practical naval gunnery; a study of the principles and practice of exterior ballistics, as applied to naval gunnery, and of the computation and use of ballistic and range tables . GUX FIEE 427. Let us now suppose that we are going to fire salvos from a l)atterv of 1^guns, for which r = 2900 f. s., w = S70 pounds and 6 = 0.(U. Let us also assume thatwe have a vertical target 30 feet high and wide enough to eliminate the necessity forconsidering lateral deviations due to accidental errors. Let us take the mean errorsof the gun in range, first as 40 yards, next as 60 yards, and then again as 80 yards;and also that they are approximately the same at all ranges. Let us also assume thatthe mean point of impact is at the center of the water-line of the target, in whichcase, as we have already seen, 50 per cent of the shot will fall short. Let us alsoassume that the three mean deviations correspond to total deviations of 150, 200and 300 yards, respectively. Xow let us see what percentage of the shot in each salvowill probably hit, at a range of 7000 yards, at which range the danger space for atarget 30 feet high is, by the range table, 180 yards. Method of Figure 45. 1. Mean dispersion in range 40 yards; maximum dispersion in range 150 yards(Figure 45). tan (0 = 30 _ 1540 18 11-0 = Ts y=^^^^ That is, for a maximum dispersion of 150 yards, or 450 feet, no shot would passmore than 25 feet above the water-line of the target, and all shots that do not fallshort would hit. Therefore, by our assumption, we would have 50 per cent of shortsand 50 per cent of hits. 3oy
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectballistics, bookyear1
