An extension of multhopp's lifting surface theory to include the effect of flaps, ailerons, etc

摘要

The subsonic lifting surface theory due to H. Multhopp (Ref. 1)has been extended to include a chordwise discontinuity in the slope ofthe lifting surface, i.e. to include the effect of flaps, or ailerons.By representing the chordwise loading of a two-dimensional flapped flatplate in closed form, a new loading function is used in the L2representation of the chordwise loading, and a new influence function kis defined. This function is dependent on the parameter ᴓh whichdescribes the hinge position, and so the tabulation which has beendone for the influence functions, i and j, in Multhopp’s original methodhave to be repeated for values of ᴓh.The method is restricted to linearized, non-viscous flow about thinwings of moderate aspect ratio of any planform. Values of lift,pitching moment and centre of pressure can be obtained across the spanfor deflected flaps, and the theoretical effect of planform can be studied.An example has been calculated for a straight rectangular wing ofaspect ratio 6 with a full span 20% chord, trailing edge flap. Acomparison with available experimental results shows that viscous effectsare important in obtaining the correct magnitudes of lift and pitching moments.