Question 10.18: Figure 10.20 illustrates the dependence of the drag coeffici...

(a) The frontal area is used to compute the drag force for the ogive, and the drag force is determined by applying Equation 10.12 F_{D} = C_{D} \frac{1}{2} \rho v^{2}A . The speed of sound,  c = \sqrt{E_{v}/\rho } (along with the density) for air at standard atmosphere at an altitude of 30,000 ft above sea level is given in Table A.1 in Appendix A.

slug: = 1 lb \frac{sec^{2}}{ft}                                     D: = 3 in = 0.25 ft                                     A_{front}: = \frac{\pi .D^{2}}{4} = 0.049 ft^{2}

V: = 3800 \frac{ft}{sec}                                           c: = 994.85 \frac{ft}{sec}                                     M: = \frac{V}{c} = 3.82

C_{D}: = 0.35                                     \rho : = 0.00089065 \frac{slug}{ft^{3}}

Guess value:                                     F_{D}: = 1 lb

Given

F_{D} = C_{D} \frac{1}{2} \rho.V^{2} . A_{front}
F_{D}: = Find (F_{D}) = 110.48 lb