Understanding avian soaring to extend UAV mission endurance through remote detection of thermal updrafts

Abstract

Thermal updrafts can be utilized to increase an aircraft's flight endurance and range. However, much of the discussion involving thermal updrafts comprise of flight techniques within a known thermal updraft and very little is discussed over the detection of thermals without the influence of the upward or downward velocity component. This paper discusses possible thermal locating methods discovered from looking at thermal detection primarily from an avian viewpoint. An avian study was conducted to gather information on how avian soaring species locate thermal updrafts, in which no definitive answer was found. Of the possible theories of avian thermal location methods, combined with methods used from RC aircraft, a single method was chosen for further study through simulation and experimentation to construct possible applications to unmanned aerial systems. By quantifying wind shifts in the local area, the direction and location of local thermal updrafts was theorized to be able to be calculated. However, due to the high magnitudes of uncertainty found during the experimental approach and then portrayed in additional simulations with added uncertainty, this method is shown to be unfavorable for use in remotely detecting thermal updrafts.