A wind-tunnel gust generator for soaring birds and small UAVs

The operation of small uncrewed aerial vehicles (SUAVs) is limited by their inability to maintain steady flight trajectories in gusty conditions. Birds, however, regularly fly in the same gusty conditions with apparent ease. The mechanisms birds use to maintain steady flight in these conditions are not well understood. A wind-tunnel gust generator was developed to produce vertical and rolling gusts to perturb soaring birds so that their gust responses may be studied. The gust generator was located downstream of the birds and modified the strength of the updraft in which the birds soared. An example downward step gust, upward step gust and rolling pulse gust were characterised to demonstrate the gust generator's performance. The gusts were highly repeatable and resulted in changes of effective angle of attack of up to 20 deg, in periods of 0.2 s. Nankeen kestrels (Falco cenchroides) successfully soared above the operational gust generator, demonstrating its potential for use in future studies.