Abstract:

ESDU 14004 considers the flat plate (deployed in a plane normal to the section chord) and flap (pivoting about a hinge) types of rectangular spoilers on the upper surface of a wing with trailing-edge flaps undeployed. It discusses the flow behaviour with variation of spoiler deployment and wing angle of attack, as well as the effect of spoiler chordwise position on wing lift-curve slope.

A method is presented for predicting the lift coefficient increment (usually negative, i.e. a decrement) and rolling moment coefficient due to spoiler deployment on the upper surface of a wing at subsonic speeds. The two-dimensional lift coefficient increment characteristics are first determined, and the corresponding three-dimensional lift coefficient increment and rolling moment coefficient characteristics are then deduced.

The method is applicable for any form of porosity (perforations, hinge-line gaps, spoiler segmentation or edge castellation) up to 0.38 of the spoiler area. Spoiler chordwise locations from 0.4c to the trailing-edge are covered for spoiler deployment height to wing chord ratios from 0.04 to 0.15. Spoiler deployment height is defined as the height above the wing surface and it is the height of the spoiler trailing-edge above the wing surface in the case of flap-type spoilers. The method is applicable for both straight-tapered and cranked wings with spoilers sweptback up to 45 degrees for Mach numbers up to 0.7. Lift increment and rolling moment behaviour is affected by wing angle of attack, and limits of applicability for both minimum and maximum angles of attack are suggested. Sketches comparing predicted data with test data show that in most cases predictions lie within 0.03 for lift coefficient increment and within 0.003 for rolling moment coefficient.