COMPARATIVE DRAG MEASUREMENTS AT TRAMIONIC SPEEDS OF RECTANGULAR SWEPTBACK NACA 65-009 AIRFOILS MOUNTED ON A FREELY FALLING BODY

L3irect[y comparable drag measurements hare been-made of an a ig%oilm“th a conventional rectangular plan. form and an- airfoil with a. sweptback p[a n form mou nted on freely falling bodies. Both airj%ik had AL4C4 65-009 aectiuna and were identical in epan, frontal area, and chord perpendicular to the leading edge. The sweptback plan form incorporated a sweepbach- angle of @=. The data obta.in-edhare been used to establish the relation between the airfoil drag coejicients and the free-stream Mach number ocer a range of Mach. numbers from 0.90 to 1.27. The results of these measurements indicate that the drag of the s creptback plan form is lese than 0.$7tfiat of the rectangular plan form at a Mach number of 1.00 and is less than O. ~ that at a Mach number of 1..20