Flight Mechanics, Flight Control and Aeroelasticity

Effects of wake vortices of very large transport aircraft on following aircraft.

This project was funded by the DFG in 1999 - 2002 and has been completed.

In connection with two research projects, the influence of wake vortices on aircraft flying into them is being investigated. Within these projects, the A340 simulation environment at the ILR will be extended to allow tests including pilots.

The wake vortices generated behind any lift-generating aircraft can have a significant impact on following aircraft. A number of aircraft accidents in recent years, especially within sport aviation, have made this spectacularly clear. If an aircraft flies into the spatially limited wake vortex of another aircraft, extraordinarily large additional aerodynamic forces and moments can be the result, which the pilots of the incoming aircraft may have great difficulty in compensating for. In order to minimize the risk of dangerous incidents, minimum longitudinal staggering between two aircraft has therefore been prescribed for many years in the field of controlled commercial aviation. These regulations are based solely on the maximum take-off weight (MTOW) of the aircraft involved and do not take into account any other effects influencing vortex development and attenuation. Since the necessary staggering limits the scarce capacities of airspace and commercial airfields, special attention has been paid to the formation and influence of wake vortices on following aircraft for several years. The aim of a wide range of research in Europe and the USA is to investigate the phenomena of vortex generation and the influence of wake vortices to such an extent that the longitudinal staggering that must be maintained for safety reasons can be made more flexible and, on the basis of more precise knowledge, reduced if necessary. Research on this topic can be divided into three areas:

  1.   Vortex avoidance - development of aircraft with favorable vortex characteristics.
  2.   Vortex prediction and detection - development of methods for estimating vortex behavior, e.g. as a function of meteorological parameters
  3.   Vortex consideration - development of methods to increase safety when entering a wake vortex.

At the department the following basics are worked on in particular:

  •   Physical mapping of the influence of a wake vortex on the aerodynamic and flight mechanical characteristics of an incoming aircraft ("encounter aerodynamics")
  •   Investigation of the safety-relevant main influencing variables - Definition of worst-case encounters
  •   Implementation of numerical programs for the representation of wake vortex effects in flight simulators (e.g. A330, Do228 FFS)
  •   Flight characteristics investigations including pilots in simulated wake vortex encounters