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 . ion to the more approximate methods thatwe have hitherto considered. It should not be forgotten, however, that the method isnot literally exact, and that it might be possible, under unusual and peculiar con-ditions, that results might vary appreciably from those actually existent in is not ordinarily necessary to consider this point, but should some unusual andpeculiar problem present it
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 . ion to the more approximate methods thatwe have hitherto considered. It should not be forgotten, however, that the method isnot literally exact, and that it might be possible, under unusual and peculiar con-ditions, that results might vary appreciably from those actually existent in is not ordinarily necessary to consider this point, but should some unusual andpeculiar problem present itself, it would be necessary to consider whether the con-ditions were such as to introduce material inaccuracies into results obtained by theordinary methods. 117. Taking rectangular axes in the plane of fire; origin at the gun; X, asalways, horizontal, and positive in the direction of projection; Y, as always, vertical,and positive upward; let V, in Figure 12, be the initial velocity, and (f> the angle ofdeparture, and let v be the remaining velocity at any point, P, of the v horizontally, we have v cos 6, and, parallel to the line of departure (65) I u=v cos 0 sec o. X Figure 13. Pseudovelocity. 118. The quantity u, which is represented in Figure 12, is known as the pseudovelocity (see definition in paragraph 22), and its use in the solution of practicalballistic problems is due to Major Siacci, and is the essence of his method. It willreadily be seen that u=V a,t the origin, where S = , and also at another point in thedescending branch of the trajectory where ^= -. At tlie_ vertex, where 6 = 0, thepseudo velocity differs most from the true velocity, its value there being ~u = vsec~^ /
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectballistics, bookyear1
