This monthly report details Engineering Department technical activities for the month of May 1947.

Wind-tunnel investigations were made in pitch and yaw with and without split flaps. Presence of the fuselage had negligible effect on values of maximum lift coefficient and slope of lift curve, but caused a destabilizing shift in the rate of change of pitching moment with lift. Effects of fuselage position on drag characteristics were small for wings without flaps, but were appreciable when split flaps were on.

The following report examines a set of beryllium metal rods through pile radiation, taking measurements, and analyzing differences between irradiated and radiated rod samples.

"An investigation has been made at large scale of the characteristics of highly swept wings. Data were obtained at several angles of sideslip on wings having angles of sweep of plus or minus 45 degrees, plus or minus 30 degrees, and 0 degrees. The airfoil sections of the wings varied from approximately NACA 0015 at the root to NACA 23009 at the tip. Each wing was investigated with flaps under flection, partial-span split flaps deflected 60 degrees, full-span split flaps defected 60 degrees and split-flap-type ailerons deflected plus or minus 15 degrees" (p. 1).