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52. 

in the original calculations (k = 1/15), but that the velocity of expulsion of the gases is the mean found by experiment for the Coston ship rockets, namely 1029.25 ft/sec. In this case the effective velocity is

c(1-k) = 1029.25 (1-1/15) = 960 ft/sec.

The third additional calculations, [[underlined]] M [[subscript]] R2 [[/subscript]][[/underlined]], are carried out for the case of a rocket built up of Coston rockets in bundles, (shown in section in Fig. 22), the lowest bundle of which is fired first and then released; after which the bundle above is fired and then released; and so on. When the Coston ship rocket has its charge of red fire removed (giving it a range, experimentally determined), of a quarter of a mile as already stated) the ratio of the powder charge to the entire mass of the rocket is found to be closely 1/4. Hence the "effective velocity" in this case is only

c(1-k) = 1029.25 (1-4/5) = 257.3 ft/sec.

The [[underlined]] M [[/underlined]]'s in the last two cases are calculated only for the accelerations that make [[underlined]] M [[/underlined]] minima for the first case (effective velocity, 7,500 ft/sec.). Hence in these cases, the [[underlined]] M [[/underlined]]'s are not minima, although only in the last two cases is there probably much discrepancy from the actual minima. 

The cross section, [[underlined]] throughout any interval [[/underlined]] is take as one square inch ^[[per pound]] except for interval [[underlined]] s [[/underlined]][[subscript]] 9 [[/subscript]]. It will be seen from the Table that this is justifiable, as the largest mass in intervals s[[subscript]] 1 [[/subscript]] to s[[subscript]] 8 [[/subscript]] does not differ much from one pound.