Examples of flight path optimisation using a multivariate gradient-search method. Addendum A: variation of optimum flight profile parameters with range.
Abstract:ESDU 94016 gives a further study to that in ESDU 93021 of optimising a complete sortie. The aircraft is the same as used in ESDU 93021, and fuel required (and hence ramp mass) is minimised for a series of ranges from 150 to 3900 n. miles under the same constraints and assumptions on fuel reserves as were previously used. The profile parameters to vary are climb and descent speed, cruise Mach number, and height at start of cruise, and a cruise-climb was used because those profile parameters showed greater sensitivity than in the more practical level or stepped cruise and so illustrated the effects better. Sketches show the effect of range on the profile flown, the height at start and end of cruise, the Mach number in climb, cruise and descent, and the ramp mass. The flight profile parameters vary little for ranges exceeding 1000 n. miles when for each range the profile effectively joins at the top of climb the optimum for 3900 n. mile range; below 1000 n. mile range significant changes occur down to 150 n. mile range to retain a cruise segment starting at progressively lower heights. Below 150 n. mile the profile is a simple climb and descent.
|Data Item ESDU 94016|