Abstract:

In constructing an aircraft performance model, it is sometimes necessary to make use of flight data that have not been expressly generated for that purpose. Such is the case in the example shown in this document, whichdemonstrates how quite severe manoeuvring flight can be used to derive aerodynamic data for a performance model.

The example is a single-engined jet aircraft that was flown through a wind-up manoeuvre at a Mach number of 0.5 and an altitude of approximately 6000 feet.

The manoeuvre was analysed to develop a performance model of the aircraft using the method described in ESDU 15001 (Aircraft performance from flight test. Part 1: derivation of a mathematical model). Tailplaneaerodynamics were available from wind-tunnel testing and a downwash model was constructed based on the method of ESDU 80020 (Average downwash at the tailplane at low angles of attack and subsonic speeds).Level flight manoeuvres were used to deduce calibrations for the angle of attack, angle of sideslip and air data pressure sensors. A wind-up turn manoeuvre was then used to obtain the aerodynamic force and moment coefficients required for performance modelling.