Data Item predicts wing lift coefficient increment at zero angle of attack due to the deployment of trailing-edge split flaps at low speeds

Citation

(1999), "Data Item predicts wing lift coefficient increment at zero angle of attack due to the deployment of trailing-edge split flaps at low speeds", Aircraft Engineering and Aerospace Technology, Vol. 71 No. 1. https://doi.org/10.1108/aeat.1999.12771aab.075

Data Item predicts wing lift coefficient increment at zero angle of attack due to the deployment of trailing-edge split flaps at low speeds

Data Item predicts wing lift coefficient increment at zero angle of attack due to the deployment of trailing-edge split flaps at low speeds

Keywords ESDU, Lift, Wings

ESDU International has issued a new Data Item (No. 97009) which predicts the increment in wing lift coefficient, at zero angle of attack, due to the deployment of trailing-edge split flaps at low speeds.

In the new Data Item, the increase in wing lift coefficient is derived from the increment due to the deployment of the split flap on an aerofoil section that is representative of the wing.

For wings with full-span trailing-edge split flaps a factor, dependent on planform geometry, is applied to allow for three-dimensional effects. For wings with part-span trailing-edge flaps additional factors are introduced, that are dependent on the wing geometry.

At low speeds, the increment in lift coefficient at zero angle of attack due to the deployment of a full-span trailing-edge split flap on a high-aspect ratio rectangular wing is strongly dependent on the corresponding value for an aerofoil/split flap combination appropriate to the mid-semispan location.

The main parameters that can influence the aerofoil lift coefficient increment are the flap angle, chord of the flap, the aerofoil maximum lower-surface ordinate and its chordwise location, the flow Reynolds number and Mach number.

For trailing-edge split flaps on wings the additional parameters that are important are the wing planform geometry (aspect ratio, taper ratio and sweep), and the spanwise extent of the flap.

The effects of wing planform geometry are largely accounted for in terms of their effect on the wing-lift curve slope. Provision is made for the case of an extended chord split flap.

Further details are available from ESDU International. Tel: +44 (0) 171 490 5151.