Experimental Analysis of the Behaviour of Flared Folding Wingtips with Sideslip Angle

A concept of growing interest in recent years is that of the Flared Folding Wingtip (FFWT), which can be used in-flight to reduce airframe loading due to gust encounters and augment the handling qualities of an aircraft. The performance of an FFWT is affected by the relative angle between the built-in hinge angle and the flow direction. Therefore, a critical question is the behaviour of such a device at a non-zero sideslip angle, where recent studies have shown that a FFWT can collide with the inner wing at sideslip angles within the flight envelope of an aircraft. In this paper the effect of sideslip angle on the stability behaviour of a wing incorporating FFWTs is investigated both experimentally and numerically. It is shown that the response of FFWTs to sideslip varies not only as a function of flare angle, but also with the angle of incidence of the aircraft and the camber or twist of the wingtip itself.