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Wake Turbulence Encounters

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Wake Turbulence Encounters Photo


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

  • Identify severities of UAS flight disruption due to wake turbulence to help FAA assess the 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 the FAA has started the wake turbulence re-categorization (RECAT) for aircraft, the current regulation categorized 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 UAS (e.g., Kitty Hawk Cora UAS, -4,000 lbs.) to small package delivery UAS (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
      • The angle of attack and sideslip perturbations due to the wake.
    • Validation and refinement of simulations with UAS flights:
      • In a controlled, indoor gust facility designed to simulate wake encounters.
      • At a controlled outdoor gust facility designed to simulate wake encounters.
      • In an 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.
    • The high-fidelity gust load measurement in a simulated wake vortex encounter.
    • The flexible damping to demonstrate new flutter prediction algorithms.

Project Lead
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Mark Ewing
Director | Flight Research Laboratory