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Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

Q2 Z2,(Q2) Z2(Q2) - Institute for Water Resources - U.S. Army

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Acceleration and Deceleration. The acceleration time and dis-<br />

tance <strong>for</strong>mulas were presented in Chapter III above and are given in<br />

Equations (3.26) and (3.27). Using the definitions of k 0 , k k 2 ,<br />

and K given in (4.15) and an appropriate value of these <strong>for</strong>mulas<br />

may be applied to barge tows. Since Lows typically operate at full<br />

•<br />

throttle, 15<br />

accelerat:ons from velocities other than zero to veloc-<br />

ities other than V f were not considered.<br />

The method of obtaining the factor ; was as follows: Equation<br />

(3.25), as applied to barge tows, was plotted <strong>for</strong> three sets of tow-<br />

waterway characteristics. These graphs are shown in Figures 4.!,<br />

4.2, and 4.3. A velocity of 0.99V f seemed to include most of the<br />

time required <strong>for</strong> acceleration while not including a large amount of<br />

time on the asymptotic portion of the acceleration curve.<br />

Examples of acceleration times and distances as predicted by<br />

Equations (3.26) and (3.27) are given in Table 4.3 <strong>for</strong> five differ-<br />

,'<br />

ent flotilla combinations. In all five cases the waterway character-<br />

istic a are assumed to be the same, viz., width equal to 225 feet and<br />

depth equal to 12 feet. These values could easily be changed; the<br />

particular values presumably typify the Illinois <strong>Water</strong>way. 16 Horse-<br />

power of the towboat was assumed to be 3000 and flotilla draft was<br />

assumed to be 8.5 feet. These also could be varied. Five flotilla<br />

sizes were assumed: (1) a four-barge flotilla, arranged two barges<br />

long and two barges wide (2 x 2); (2) a nine-barge flotilla, arranged<br />

three barges long and three barges wide (3 x 3); (3) a twelve-barge<br />

flotilla, arranged four barges long and three barges wide (4 x 3); .<br />

(4) a fifteen-barge flotilla, arranged five barges long and three<br />

79

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