Abstract:

ESDU 74012 gives curves derived from lifting-surface calculations for correcting lift increment due to deflection of a full-span flap to give the increment for a part-span flap with arbitrary spanwise position. The curves are a function of wing sweep, taper and aspect ratio and apply to straight-tapered wings. They may be used with the full-span increments from ESDU 74009 for split flaps, from ESDU 74011 for plane flaps used as controls, and from ESDU Aero F.01.01.08 and ESDU F.01.01.09 for single-slotted and double-slotted flaps, respectively. However, ESDU 74009, ESDU F.01.01.08 and ESDU F.01.01.09 have been superseded by ESDU 97009, ESDU 93019 and ESDU 95021, respectively, and each of those contains its own dedicated part-span factor. Those methods should always be used for estimating the lift increment rather than the methods in the earlier Items, which are retained temporarily only because they are referred to in other documents in the Series. Predictions from the curves of ESDU 74012 have been compared with experimental data from 25 sources and are found to yield the ratio of the increment in lift coefficient due to part-span flaps to that due to full-span flaps to within 0.1.