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Related Experiment Video

Updated: Jun 9, 2025

Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods

Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods

Published on: April 23, 2018

Distributed feather-inspired flow control mitigates stall and expands flight envelope.

Girguis Sedky¹, Nathaniel Simon¹, Ahmed K Othman¹

¹Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544.

Proceedings of the National Academy of Sciences of the United States of America

|October 28, 2024

Summary

Researchers studied bird wing covert feathers to understand their aerodynamic role. They found that multiple covert-inspired flaps can enhance aircraft controllability by mitigating stall and improving aerodynamic benefits.

Keywords:

aerodynamics bioinspired design bird flight covert feathers flow control

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Area of Science:

Aerodynamics
Bio-inspired engineering
Fluid mechanics

Background:

Covert feathers on bird wings deploy passively during high angle of attack maneuvers.
These feathers are suggested to play an aerodynamic role, but their flow physics and the function of multiple rows are not well understood.

Purpose of the Study:

To identify flow control mechanisms of single covert-inspired flaps.
To assess the additivity of these mechanisms with multiple rows.
To investigate the aerodynamic role of covert feathers in avian flight and their application in aircraft.

Main Methods:

Wind tunnel experiments were conducted to analyze flow physics.
Multiple rows of covert-inspired flaps were deployed.
Tests were performed on a bird-scale remote-controlled aircraft.

Main Results:

Two flow control mechanisms were identified: a pressure dam and a shear layer interaction.
Shear layer interaction benefits were additive with multiple rows; pressure dam benefits were not.
Both mechanisms can be exploited simultaneously for maximum aerodynamic benefits and stall mitigation.

Conclusions:

Covert-inspired flaps can enhance aircraft controllability.
Passive deployment trends in flight tests mimic bird flight.
The study provides insights into the aerodynamic function of covert feathers in avian flight.