Column and plate compressive strengths of extruded 0-1HTA magnesium alloy were determined both within and beyond the elastic range from tests of flat end H-section columns and from local instability tests of H-, Z-, and channel section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures.

Note presenting three temperature-height relationships and one composition-height relationship developed by the NACA and tables based on them for pertinent properties of the upper atmosphere. Two sets of tables based on the adopted tentative standard specifications for the upper atmosphere are presented.

Results are presented of tests to determine the effect of brake forming in various tempers on the strength of Alclad 75S-T aluminum alloy sheet in the direction parallel to the brake. The tensile and compressive strengths of Alclad 75S-T sheet, formed in the O and W tempers, were either increased or little affected compared with those of similarly treated unformed material. When Alclad 75S-T sheet 'as received' was formed, however, the tensile yield stress was reduced about 7 percent for the with-grain direction and 1 percent for the cross-grain direction, whereas the tensile ultimate and compressive yield stresses were increased somewhat. The elongation was always slightly reduced as a result of forming.

Note presenting pressure distributions and force measurements in the two-dimensional low-turbulence pressure tunnel at low Mach numbers and high Reynolds numbers of an NACA 65-210 airfoil equipped with a 50-percent-chord plain flap. Tests were carried out for flap deflections of 0, 4, 7, and 10 degrees. These flap deflections provided considerably reduced drag coefficients at life coefficients above the design range of the plain airfoil.

Report presenting an extension of previous work on the theory of self-excited mechanical oscillations of hinged rotor blades. This particular report details the missing case of one or two blades on unequal supports. Results regarding types of instability, general behavior of rotor system as a function of rotor speed, and effect of damping is provided.

Strain measurements and strength tests were made on six skin-stringer panels under axial load. Three of these panels had short rectangular cut-outs, and three a long one. The width of the cut-out was about one-half of the width of the panel. Three types of coating stringers were used: without reinforcement, with riveted-up reinforcement, or with integral reinforcement. The strain measurements were found to be in good agreement with a previously published theory adapted where necessary by making overlapping assumptions.

From Summary: "Strength tests were made of a number of 24S-T and Alclad 75S-T aluminum alloy shear webs to determine the effect of rivet or bolt holes on the shear strength. Data were obtained for webs which approached a condition of pure shear stress as well as for webs with well-developed diagonal tension. The rivet factor (pitch minus diameter), divided by pitch, was varied from approximately 0.81 to 0.62. These tests indicated that the shear stresses on the gross section were nearly constant for all values of the rivet factor investigated if the other properties of the web were not changed."

Report presenting a consideration and evaluation of the effects of several parameters on the drag characteristics of practical construction wing sections. The effects considered were those of surface roughness, surface waviness, compressive load, and de-icers.

The shock expansion method of the NACA TN No. 1143 was used to determine the principal aerodynamic characteristics of two-dimensional supersonic airfoils. A discussion is given of the effect of thickness ratio, free-stream Mach number, angle of attack, camber, thickness distribution, and aileron deflection. The calculations indicated that the minimum drag of supersonic airfoils is obtained when the maximum thickness is behind the 0.50 chord. The center of pressure obtained for a symmetrical supersonic airfoil was found to be ahead of the 0.50 chord.

Solutions of the Hugoniot shock equations and Meyer expansion equations are plotted in such a manner as to permit the pressure distribution, the local Mach number, and the angles of shock waves on arbitrary sharp-nose airfoils at supersonic speeds to be obtained directly. (author).

Report presenting an investigation of the lateral-control characteristics of several spoiler arrangements located near the wing trailing edge in flight. In all cases, the control response was satisfactory and the variation of rolling effectiveness with control deflections was smooth and nearly linear. Results regarding response characteristics, rolling effectiveness, control-force and hinge-moment characteristics, yawing characteristics, effects of altitude, characteristics near the stall, and characteristics in inverted flight are provided.

Report presenting measurements of the velocity distributions at the outlet of a large number of duct elbows of round and elliptical as well as square and rectangular cross section at a range of Reynolds numbers. Special investigations include measurements of the decay of velocity patterns produced by curved ducts and the effect of asymmetrical upstream velocity distributions. Results regarding typical distributions, tabulation of principal results, and special investigations are provided.