Derivation of lateral and vertical gust statistics from in-flight measurements

An in-flight tail load measurement program has been carried out in The Netherlands in order to validate the procedures that are currently used for the determination of tail load spectra and to improve the statistical knowledge of gusts and manoeuvres, with respect to tail loads. In this measurement program tail loads, including lateral accelerations of the rear fuselage and vertical centre of gravity accelerations, have been obtained from a commercially operated Fokker 100 aircraft flying European routes. The paper describes how the vertical and lateral gust statistics have been derived from measured accelerations. A comparison is made between vertical and lateral gust statistics, both for discrete and continuous types of gusts. Vertical gust statistics (discrete and PSD) compared very well with results from FAA/NLR report. Also the continuous (PSD) gust statistics for lateral gusts compared very well with the results found for vertical gusts. The derived lateral (discrete) gust velocities however produced results that are not in line with the vertical gust velocities, indicating that care should be taken with the application of the discrete lateral gust approach.