Wake Turbulence Encounters (A35_A11L.UAS.75)

The research team consisting of University of Kansas and The Ohio State University will work together to:

  • Identify seventies of UAS flight upset due to wake turbulence to help FAA assess risk of upset and to develop policy, guidance, and procedures for mitigating UAS wake turbulence encounters.
  • Demonstrate safe flutter flight testing procedures for UAS.

Although FAA has started the wake turbulence re-categorization (RECAT) for aircraft, the current regulation put all aircraft with the maximum takeoff weight (MTOW) less than 15,500 lbs. as Category F. New separation rules and guidance to UAS/airport operators are needed to guide safe UAS operations in controlled or uncontrolled airspace including at or around airports, ranging from big passenger UASs (e.g., Kitty Hawk Cora UAS, -4,000 lbs.) to small package delivery UASs (less than 50 lbs.).

Detailed research will include:

  • Literature review in the area of UAS response to wake turbulence.
  • Determination of research shortfalls and development of case studies to address shortfall areas.
  • Analysis and assessment of the severity of upset for representative UAS responding to encounters with wake vortices with varying strengths using:
    • Physics-based simulations based on 6-degree of freedom models of UAS response to wake encounters with closed-loop flight control engaged:
      • Using computational fluid dynamics (CFD) analysis to provide pressures, forces, and moments due to the wake.
      • For fixed wing and Vertical Take-Off and Landing UAS in forward flight, using a quasi-static force and moment method based on instantaneous angle of attack and sideslip perturbations due to the wake.
    • Validation and refinement of simulations with UAS flights:
      • In controlled, indoor gust facility designed to simulate wake encounters.
      • At controlled outdoor gust facility designed to simulate wake encounters.
      • In airport environment.
    • Establishment of metrics of importance for upset prediction, both physical (mass, wingspan, rotor diameter, etc.) and derived (control authority and controllability).
    • Provide quantitative flight test support for assessing the gust response and flutter margins of existing and future UAS concept vehicles.
      • High-fidelity gust load measurement in simulated wake vortex encounter.
      • Flexible damping to demonstrate new flutter prediction algorithms.



Mark Ewing
Associate Professor
Director of the Flight Research Laboratory
University of Kansas
Email: mewing@ku.edu
Phone: 785.864.2964


Participating Schools

Ohio State University
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