Wind-tunnel investigation of control-surface characteristics VI : a 30-percent-chord plain flap on the NACA 0015 airfoil

Force-test measurements in two-dimensional flow have been made in the NACA 4-by 6-foot vertical tunnel""of the oharaoterist'ics of an MAOA 0015 airfoil equipped with a plain flap having a ohord 3Qperoent of the airfoil chord and a "plain tab having a ohord 20 percant of the flap ohord.The results are presentedin the form of aerodynamic seotion charaoteristios for several flhp and tab deflections and for a sealed and an unsealed gap at the flap nose.The slope of the lift ourve of the NAOA 0015 airfoil was slightly less than the slope of the corresponding curve for the previously tested NACA 0009 airfoil, but the effectiveness of the plain flap in producing.inorements of :lift was praotioally the same for both airfoil~ FOr the thioker airfoil, the,variation of flap hinge moment with angle of attack was about one-third and with flap deflection about orie-half. of that for the similar flap on the thinner airfol~.Unsealing the gap at the flap hinge axis had a greater effect on the oharaoteristios of the 16-percent-thick airfoil than on those of the 9-percentthiok "airfoil. .---------