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Design Report Guided Missile Submarine SSG(X) - AOE - Virginia ...

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<strong>SSG</strong>(X) <strong>Design</strong> – VT Team 3 Page 75<br />

The total SHP for the snorkel condition is the summation of the submerged SHP and the wave-induced SHP.<br />

To obtain an accurate wave induced coefficient of drag, a sixth degree polynomial is fitted to a drag curve provided<br />

by Captain Jackson’s propulsion notes. The calculation of the endurance snorkel is given in Figure 70.<br />

Snorkel Ra nge:<br />

SHPsnrkv = 797.568kW<br />

Froude # for Cdw Coef Calc:<br />

Vesnork<br />

Fn<br />

( g⋅LOA) .5<br />

:=<br />

CDW 3561.3Fn 6<br />

⋅ 8812.6Fn 5<br />

− ⋅ 8148.4Fn 4<br />

+ ⋅ 3454.3Fn 3<br />

− ⋅ 654.09Fn 2<br />

:=<br />

+ ⋅ − 40.235Fn ⋅ + .2726<br />

CDW = 1.25<br />

CW :=<br />

4⋅<br />

Wave Induced:<br />

SHPW CW⋅S⋅ρSW Vesnork 3<br />

:= ⋅<br />

SHP Snorkel:<br />

SHPsnrk := SHPsnrkv + SHPW<br />

Endurance Snork Calculation:<br />

FRSPsnk := f1⋅SFCsnk FRAVGsnk := 1.05⋅FRSPsnk PsnkAVG :=<br />

Esnork :=<br />

⎡⎛<br />

⎢⎜<br />

⎣⎝<br />

LOA<br />

D<br />

⎞<br />

⎟<br />

⎠<br />

CDW<br />

− 1.3606<br />

SHPsnrk + KW24AVG<br />

ηelec<br />

Fn = 0.227<br />

⎤ ⎛<br />

⎥⎦ ⎜<br />

⎝<br />

( )<br />

Wfsnk⋅Vesnork⋅TPA PsnkAVG⋅FRAVGsnk LOA<br />

D<br />

⎞<br />

⎟<br />

⎠<br />

2<br />

CW 7.355 10 4 −<br />

= ×<br />

SHPW = 327.351kW<br />

SHPsnrk = 1125kW<br />

FRSPsnk 0.495 lbf<br />

=<br />

kW⋅hr FRAVGsnk 0.52 lbf<br />

=<br />

kW⋅hr PsnkAVG = 1878hp<br />

Esnork = 5612nm<br />

Figure 70 - Calculations for Snorkel<br />

The snorkel range does not meet the ORD requirement. Including the wave-induced drag increased the power<br />

required by 300 kW. Forty long tons of fuel were added to satisfy the requirement. The last equation in Figure 70<br />

shows the calculations performed after the fuel was added so that the range now meets the required value.

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