Nomenclature a = acceleration normal to flight path, g's A = aerodynamic reference area, ft 2 CD = D/qA, drag coeff (D = drag, Ib)-acceleration of gravity on earth, 32.2 fps h = altitude measured from earth's surface, naut mile, or angular momentum lot Ii -zer° an d first-order modified Bessel function, respectively m = mass, slugs Q = right-hand side of differential Eq. (9) q = dynamic pressure = pF 2 /2, psf r -radial distance from earth's center = R + h, naut mile R = earth's radius, 3440 naut mile t = time, sec V = velocity, fps W = weight = mg, Ib X, Y, Z = radial, planer, and lateral forces, respectively, Ib a.= angle of attack, rad l/f3 = atm scale height, naut mile A = perturbation quantity y = r" 1 , (naut mile)" 1 = lateral spherical coordinate, measured from unperturbed orbital plane, rad p -density, slugs/ft 3 a-= -2/3r 0 (ATYy 0 )retro, or (-1/2)0 Ar, Eq. (20) 6 = polar spherical coordinate measured in unperturbed orbital plane from apogee, rad 8 = inclination of thrust axis from flight path, deg Subscripts o = initial or unperturbed orbital condition R = at earth's surface