Bird-inspired reflexive morphing enables rudderless flight

Gliding birds lack a vertical tail, yet they fly stably rudderless in turbulence without needing discrete flaps to steer. In contrast, nearly all airplanes need vertical tails to damp Dutch roll oscillations and control yaw. The few exceptions that lack a vertical tail either leverage differential drag-based yaw actuators or their fixed planforms are carefully tuned for passively stable Dutch roll and proverse yaw. Biologists hypothesize that birds stabilize and control gliding flight without rudders by using their wing and tail reflexes, but no rudderless airplane has a morphing wing or tail that can change shape like a bird. Our rudderless biohybrid robot, PigeonBot II, can indeed damp its Dutch roll instability (caused by lacking vertical tail) and control flight by morphing its biomimetic wing and tail reflexively like a bird. The bird-inspired adaptive reflexive controller was tuned in a wind tunnel to mitigate turbulent perturbations, which enables PigeonBot II to fly autonomously..., , , # Bird-inspired reflexive morphing enables rudderless flight

[https://doi.org/10.5061/dryad.zkh1893h5](https://doi.org/10.5061/dryad.zkh1893h5)

## Description of the data and file structure

### PigeonBotII.STEP

PigeonBotII.STEP is a STEP AP214 3D CAD file of PigeonBot II.

Software: Prepared in Solidworks 2023. Compatible with most CAD software. A free web-based alternative to view this file is [Autodesk Viewer.](https://viewer.autodesk.com/) 

### PigeonBot\_II\_datasupplement.xfl

PigeonBot_II_datasupplement.xfl is a xflr5 project file for simulating open-loop dynamic stability of PigeonBot II's three-by-three wing and tail morph combinations. 

Software: Prepared in xflr5 v6.61. [xflr5](https://www.xflr5.tech/) is free. 

### WindTunnelTrials.mat

WindTunnelTrials.mat is a MATLAB data file containing PigeonBot II virtual flight data in the wind tunnel.

Software: Prepared in MATLAB R2018b. Free alternatives are [HDF5 for Python](https://www.h5py.org/) or [GNU Octave](https://octa...