A robotic dove suggested a way to design an airplane without a tail fin.

Birds gliding in the sky lack a vertical tail fin, yet they maintain stability during turbulence without the need for separate flaps. In contrast, airplanes require vertical stabilizers to control their course and prevent rolling to the side during the so-called Dutch roll effect. These oscillations, resembling the movements of figure skaters, occur when the lateral stability of the aircraft is significantly greater than its directional stability.

If birds can manage without a vertical stabilizer by continuously altering the shape of their wings and tails, modern pilots achieve roll, pitch (nose-up/nose-down), and yaw stability through rudders and ailerons on the wings. These three axes of rotation define the orientation of the aircraft relative to a normal coordinate system or its center of mass along three axes.

Researchers noted that pitch can also be stabilized using the sweep of the aircraft's wings or curved aerodynamic profiles, allowing for the potential elimination of horizontal stabilizers. However, vertical stabilizers remain essential, providing the "iron bird" with directional stability, controllability, and balance around the vertical axis.

To illustrate how birds continuously adjust the shape of their wings and tails, scientists developed a robotic model called PigeonBot II. It consists of a biomimetic skeleton and 52 (40 primary and 12 tail) real pigeon feathers. These feathers form wings and a tail that can extend, lift, and tilt side to side. The design incorporates an algorithm that mimics the neuromuscular reflexes believed to be used by birds for flight stabilization.

The overall weight of the model is approximately 300 grams, comparable to that of a pigeon. The design also includes nine servos and two small propellers mounted on each wrist, allowing the robot to ascend, circle, descend, and fly in various poses.

Initially, the researchers conducted tests in a wind tunnel (without propellers) to calibrate the adaptive reflexive controller. This enabled the robot to mitigate turbulent disturbances and successfully complete outdoor experiments.

According to the researchers, their work could lead to the development of a more economical and lightweight aircraft design without a vertical stabilizer. Furthermore, the proposed solution may help reduce the radar visibility of jet fighters, enhancing their effectiveness.

The scientific study is published in the journal Science Robotics.