Optimal Pitch Thrust-Vector Angle and Benefits for all Flight Regimes

ABSTRACT The NASA Dryden Flight Research Center is exploring the optimum thrust-vector angle on aircraft.Simple aerodynamic performance models for various phases of aircraft flight are developed andoptimization equations and algorithms are presented in this report. Results of optimal angles of thrustvectors and associated benefits for various flight regimes of aircraft (takeoff, climb, cruise, descent, finalapproach, and landing) are given. Results for a typical wide-body transport aircraft are also given. Thebenefits accruable for this class of aircraft are small, but the technique can be applied to otherconventionally configured aircraft. The lower aerodynamic characteristics of fighters generallywould produce larger benefits than those produced for transport aircraft. NOMENCLATURE a, b, c quadratic equation coefficientsacceleration along the flightpath axisdrag coefficientminimum lift coefficient; lift coefficient caused by flap deflection at D drag E aerodynamic efficiency, lift-to-drag ratio, rolling or braking friction forceFPA flightpath angleforces along the flightpath axisforces perpendicular to the flightpath axis g acceleration caused by gravity k efficiency factor in quadratic drag equation L lift forcelift-to-drag ratio L