Larger commercial aircraft usually comprise high lift systems that include flow influencing control surfaces on the leading edge and/or the trailing edge of a main wing. For example, so-called trailing edge flaps are distributed along a region of a trailing edge and may be extended from a retracted state into a desired deployed position, which may depend on the actual lift requirement, the angle of attack of the aircraft and a desired velocity. Trailing edge flaps are highly diversified and may be realized by slotted flaps, fowler flaps, slotted fowler flaps, split flaps, etc. Most commonly, single or double slotted fowler flaps are used on larger commercial aircraft.
The integration of certain systems into an aircraft often follows a trade-off between flight performance, weight, integration costs, reliability, mechanical complexity and maintenance requirements. While for example the integration of a double slotted fowler flap system into an aircraft may be more expensive and more complex than a single slotted flap system, the flight performance may be clearly improved.
In order to achieve a certain gain in flight performance and especially in realizing a maximum lift coefficient CL it is possible to choose from existing high lift systems and especially flap systems during the design of an aircraft. Known flap systems may provide for a rather rough gradation in achievable flight performance characteristics. Hence, a chosen flap system may have clear performance reserves compared to other flap systems, which have not been chosen for the design, that may not have provided a sufficient performance.