Flow Angles

The aircraft’s velocity U components in the body axes can be defined in terms of its magnitude ф, and the angles of attack a and sideslip angle в, or vice versa. In the standard convention these relations are

Ucb 1 ( cos a cos в 1

Uyb = —V = vj sin в (9.8)

Ub sin a cos в

= sjm2+ю2 + (w

a = arctan (ub/U£^ (9.9)

(3 = arctan (lly / J{Ub)‘2 + {Ub)2^j

so that {Up, Up, UZZ} and [ф, a, в} are equivalent alternative parameter sets, related by the reciprocal relations (9.8) and (9.9).