Comparing aircraft wake turbulence categories with induced power calculation

Abstract

Purpose – Definition of new Wake Turbulence Categories (WTC) based on the calculation of induced power of aircraft on approach. This requires the parameters aircraft mass, span, approach speed, air density, and Oswald factor (calculated from wing aspect ratio, wing sweep, wing taper ratio, winglet height, and fuselage diameter). This is considerably more detailed than other metrics based on aircraft mass only or aircraft mass together with wing span. Methodology – 89 different aircraft are selected which vary significantly in their parameters. Parameters are determined from the Internet; Oswald factor and induced power is calculated. Suitable boundaries of the new WTC (CAT I, II, III, IV) are determined based on induced power. Aircraft with their new categories are presented and compared to FAA, EUROCONTROL, CAA and ICAO WTCs. Findings – Induced power can be derived not only from induced drag (as a function of lift), but also from the energy in the vortex. When compared to FAA, EUROCONTROL, CAA and ICAO WTC, the new Wake Turbulence Categories seems to offer categorization with more consistency. Research limitations – New (reduced) wake separation minima are not considered. Physics based separation minima would need a double classification of each aircraft: a) classification related to wake vortex generation as done here and b) classification related to rolling resistance. Wake separation minima would then be allocated from a pairwise comparison. Practical implications – Physics based WTC may categorize more reliable, which increases safety when applied to given separation minima. Originality – Induced power has not been used as metric for wake turbulence before.