Aerodynamic Characteristics of Wings With Cambered External-Airfoil Flaps, Including Lateral Control, With a Full-Span Flap

The results of a wind-tunnel investigation of the N. A. C. A. 23012, the N. A. C. A. 23021, and the Clark Y airfoils, each equipped with a cambered external-airfoil flap, are presented in this report. The purpose of the research was to determine the relative merit of the various airfoils in combination with the cambered flap and to investigate the use of the flap as a combined lateral-control and high-lift device.

Each of the three airfoils was tested in combination with a flap having a chord 20 percent of the main wing chord. The airfoil giving the best characteristics was then tested in combination with a 30-percent-c flap. A satisfactory flap hinge-axis location was selected from the data already obtained and final force and lateral-control tests were made with the 20-percent-c flap hinged at this point. In the lateral-control tests, the flap was cut at the center line of the model so that the semispan flaps could be deflected as ailerons with respect to each other. The flap was also cut at points one-half the semispan from each tip, permitting use of 25 percent of the span on each tip as a combined aileron and flap, the center 50 percent of the span being used solely as a flap.