NACA-TN-1351

Abstract

INTRODUCTION <br>A great amount of work has been done to determine span-loading characteristics of swept wings from purely theoretical considerations, and many computation methods are now available, some based on lifting-line theory and some based on lifting-surface theory. These methods give the span loading to various degrees of accuracy, depending on the assumptions made, which in turn govern the amount of labour expended to obtain a solution. The purpose of this investigation was, therefore, to compare theoretical span-loading results with measured values to determine the practicability of using the simpler computation methods on wings having moderate amounts of sweep. <br>Test were conducted in the 6-by 6-foot section of the Langley stability tunnel on two models a semispan wing swept forward 12&#176; and a semispan wing swept back 23&#176;- in order to determine span loading, lift, drag, pitching moment, and stalling characteristics. The semispan swept-back wing was the left panel of a full-span swept-back wing that had previously been tested in the Langley propeller-research tunnel. (See appendix) The test described in the appendix were conducted on the swept-back wing along and on the same wing with a center plate and spoiler which simulated the boundary layer on the tunnel wall for the semispan tests. The purpose of the full-span tests was to determine the effect of the tunnel-wall boundary layer on the span loading of the semispan model. The spanwise variation of profile drag was also determined in the full-span tests. Data from the tests described in the appendix are included herein for comparison. <br>The test models had no elevons but, by integration of pressures, generalized curves of the variation of hinge-moment coefficient with angle of attack were calculated for several assumed alevon plan forms.