Aeroelasticity#Flutter

As flutter refers to an undamped vibration of an aircraft, one of the effects of flutter Aero elasticity.

At this vibration all parts or masses of the aircraft are generally involved. Physical factors are rigid degrees of freedom ( translation and rotation ) in cooperation with the elastic deformation of the aircraft, the distribution of mass and the non-stationary aerodynamic forces ( the vibrating aerodynamic surfaces ).

Flutter can be influenced by design measures. In general, there is always a limit velocity occurs from the flutter. Accordingly, this limits the safe operating range of the aircraft. Since flutter usually leads to failure of the component concerned and possible related to the crash of the plane, is given to him in the testing phase special attention.

The phenomenon occurred in aircraft for the first time in the 1930s, as a significantly higher speeds were possible and the mechanisms were not initially understood. For the second time in the eyes of the developers came fluttering in the 1940s, when it was possible to fly with the speed of sound. For example, at the German Research Institute for Aviation in Berlin- Adlershof from, inter alia, Alfred Teichmann worked on it.

Today, this phenomenon is controlled, but it is theoretically not completely understood and it requires in the design of a new aircraft experiments in order to ensure operational safety.

Flapping occurs when a vibrational mode with a second or approximately equal frequency vibrating - for example, a bending mode and a torsional mode - resonates and these interfere constructively. These natural frequencies are basically depending on the construction and are differentially excited at different airspeeds.

A typical example of the flutter of aircraft parts, the bending and torsional vibrations of the airfoil. The rudder (elevator, rudder, ailerons) can flutter at too low stiffness in the suspension or articulation, which is exacerbated by too much play. Propeller can be excited by the precession to flutter.

• Flight control
• Aerodynamics