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 . s. 60 yards. 80 yards. Percentage of— Percentaj:e of— Percentage of— Shorts. Hits. Overs. Shorts. Hits. Overs. Shorts. Hits. Overs. 7000 50 50 0 50 49 1 50 46 4 180 10000 50 49 1 50 42 8 50 35 15 108 13000 50 42 8 50 32 18 50 25 25 70 15000 50 36 14 50 27 23 50 21 20 55 18000 50 28 22 50 20 30 50 15 35 39 ACCURACY AND PEOBABTLITY OF GUN FIRE 257 The above mean dispersions are less than ha
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 . s. 60 yards. 80 yards. Percentage of— Percentaj:e of— Percentage of— Shorts. Hits. Overs. Shorts. Hits. Overs. Shorts. Hits. Overs. 7000 50 50 0 50 49 1 50 46 4 180 10000 50 49 1 50 42 8 50 35 15 108 13000 50 42 8 50 32 18 50 25 25 70 15000 50 36 14 50 27 23 50 21 20 55 18000 50 28 22 50 20 30 50 15 35 39 ACCURACY AND PEOBABTLITY OF GUN FIRE 257 The above mean dispersions are less than have been experienced at recent targetpractices. The above chances of hitting are based only on vertical errors; if the target beshort they will be materially reduced by the lateral errors. 428. For the above problem let us now suppose that the mean point of impacthad been at the center of the danger space, instead of at the water-line, and we haddesired to tabulate the same data as before. Let us start with the range of 7000yards, for which the danger space is 180 yards, and compute the results for a meandispersion in range of 40 yards, corresponding to a total dispersion of 150 Figure 47. All shot that fall less than 270 feet short of the mean point of impact are space between mean point of impact and target, n 270 9 -^ = ;-i^ = 4= P=.9275 y 130 4 Therefore, for those short of the mean point of impact, per cent will hit per cent will fall short. But only 50 per cent of the total number of shot firedfall shot of the mean point of impact, therefore the above percentages become, of thetotal. Hits per cent Shorts per cent For the space between .4 and (, wliich is 270 feet, we know that any shot that fallsbetween A and C hits, and any that falls l)eyond ( is over. Therefore the work is thesame as the above, and we have Hits per cent Overs per cent Therefore the total is Shorts per cent Hits per cent Over
Size: 2606px × 959px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectballistics, bookyear1
