BigBird XL

  BigBird Copyright: © Marco Denuder, ETH Zürich

Fully Automatic UAV with Flapping Wing Propulsion


Objectives and Approach

In this project an Unmanned Aerial Vehicle implementing the concept of flapping wing flight is being developed. Characteristic for this type of propulsion, also known as Coupled Bending and Torsion (CBT), is the functional integration of both lift and thrust generation in the wings of the aircraft. Just like in nature, this feature leads to almost noiseless and highly efficient flight. BigBird XL has been designed for a maximum takeoff weight of 25 kilogram with a payload of up to 10 kilogram. Flight operations, including takeoff and landing, will be fully automated.

BigBird XL is based on the project SmartBird from the year 2011, video, which was financed by Festo.

The Institute of Flight System Dynamics is responsible for the flight dynamic modeling of the aircraft, the flight controller design as well as for planning and executing all free flight tests. Further tasks include the development and integration of avionic components and sensors.

BigBird XL is superior to UAVs with conventional propulsion in some crucial aspects.

Advantages of BigBird XL

Low noise

Propeller aircrafts generate sound pressure waves, which interfere with humans and wildlife. Although their intensity can be reduced by different types of constructive measures, propeller noise cannot be altogether avoided. The wing beat of birds is in contrast very quiet and generates sound at a very low frequency, which is no longer perceived by a human at a distance of only a few meters. Therefore BigBird XL can be successfully deployed in noise sensitive areas like residential districts and wildlife preserves.


With the CBT motor an aerodynamic efficiency of over 80 percent can be achieved. This would make BigBird XL more efficient than most known propeller driven UAVs. The high efficiency makes the aircraft suitable for long distance runs, for example inspection flights over large areas as well as for high payload transport flights.

Flight aesthetics

Because of its bionic drive BigBird XL will be perceived not as a manmade aircraft, but rather as a bird. This can be very important when it comes to not being recognized, for example during wildlife observations.


Multicopters as well as some propeller driven fixed-wing airplanes will plummet unchecked to the ground, if their systems should fail. In the case of an accident people could be injured by falling debris or by sharp rotating propeller blades. If system failure occurs the wings of BigBird XL lock to a V position, just like those of a landing bird, thereby allowing a soft and slow glide to the ground. BigBird XL offers advantages for all applications where safety is of major concern.

Project Associates

  • Effekt-Technik GmbH
  • JNTec GbR
  • RWTH Aachen University – Institute of Flight System Dynamics
  • Steinbeis Innovation gGmbH