UNMANNED ROTORCRAFT IN AGGRESSIVE ENVIRONMENT: AERODYNAMIC FLOW PERFORMANCE AGAINST WIND GUST

Abstract

Unmanned rotary-wing aircrafts or rotorcrafts are often prone to diverse atmospheric turbulences, and undeniably, abrupt gusts are reckoned to be the most acquainted commotion of them. Time and again, gust turbulence have dictated being the regulating trigger for countless mishaps concerning micro aerial vehicles. Given that the core/main rotor provides principal lift along with governing directional control and dynamic stability for any rotorcraft, the demeanors of thrust or induced air-flow through the gyrating blades largely signify the barebones of its functionality. This paper presents an idiosyncratic approach towards reviewing the impact of wind gust on rotor induced aerodynamic flow performance of an unmanned rotorcraft. Artificial gusts have been generated through the inherent concept of forced pitched oscillation without the use of any conventional wind tunnel. Gust air-speed and the rotor induced air-speed are gauged through the same contraption to provide homogeneous quantitative valuation. Each rotor-halves have been assessed `root-to-tip' across designated span-wise positions against selected strengths of gust. Comparative analysis with normal atmospheric condition indicated gradual loss of cumulative thrust during hover (15-40%) and forward flight (10-30%) within the stipulated gust range and infers the risk of declining altitude. Protuberant imbalance of thrust across the rotor disk during hover indicated the likelihood of lackadaisical half-pitched rolling motion. However, during forward flight, the reduced discrepancy of thrust between the rotor halves signified gradual loss of cruising speed with regards to the increasing gust strength for the specific rotorcraft model. Experimental findings in this study exhibited prospect of appraisal with full-scale rotorcrafts.