Covert-inspired flaps: an experimental study to understand the interactions between upperwing and underwing covert feathers

Diaa A. Zekry, Taewoo Nam, Rikin Gupta, Yufei Zhu, Aimy A. Wissa

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Birds are agile flyers that can maintain flight at high angles of attack (AoA). Such maneuverability is partially enabled by the articulation of wing feathers. Coverts are one of the feather systems that has been observed to deploy simultaneously on both the upper and lower wing sides during flight. This study uses a feather-inspired flap system to investigate the effect of upper and lower side coverts on the aerodynamic forces and moments, as well as examine the interactions between both types of flaps. Results from wind tunnel experiments show that the covert-inspired flaps can modulate lift, drag, and pitching moment. Moreover, simultaneously deflecting covert-inspired flaps on the upper and lower sides of the airfoil exhibit larger force and moment modulation ranges compared to a single-sided flap alone. Data-driven models indicate significant interactions between the upper and lower side flaps, especially during the pre-stall regime for the lift and drag response. The findings from this study are also biologically relevant to the observations of covert feathers deployment during bird flight. Thus, the methods and results summarized here can be used to formulate new hypotheses about the coverts role in bird flight and develop a framework to design covert-inspired flow and flight control devices for engineered vehicles.

Original languageEnglish (US)
Article number046021
JournalBioinspiration and Biomimetics
Issue number4
StatePublished - Jul 1 2023

All Science Journal Classification (ASJC) codes

  • Engineering (miscellaneous)
  • Molecular Medicine
  • Biophysics
  • Biochemistry
  • Biotechnology


  • bio-inspired flight control
  • covert-inspired flaps
  • feather-inspired flaps


Dive into the research topics of 'Covert-inspired flaps: an experimental study to understand the interactions between upperwing and underwing covert feathers'. Together they form a unique fingerprint.

Cite this