From Summary: "The analysis of results of wind-tunnel stability and control tests of powered airplane models in terms of the flying qualities of full-scale airplanes is advocated. In order to indicate the topics upon which comments are considered desirable in the report of a wind-tunnel stability and control investigation and to demonstrate the nature of the suggested analysis, the present NACA flying-qualities requirements are discussed in relation to wind-tunnel tests. General procedures for the estimation of flying qualities from wind-tunnel tests are outlined."

Report presenting performance tests of thermal ice-prevention equipment designed and installed in the XB-24F airplane in icing and non-icing conditions. The recorded temperature and air-flow data, and the calculated quantities of heat flow throughout the system are presented in tabular form.

Report presenting an investigation in the 19-foot pressure tunnel of two-tapered wings with NACA 230-series airfoil sections, straight leading edges, and constant-chord center sections. Lift, drag, and pitching-moment coefficients were determined for the plain wing and for each flap arrangement for a range of Reynolds numbers. The results indicated that the wing with the square center section has greater maximum lift coefficients and increments of maximum lift due to flap deflections than the wing with the rectangular center section.

Report presenting the results of an investigation made in the two-dimensional low-turbulence pressure tunnel of surface irregularities on a low-drag airfoil section. The primary objective was to determine the effects of riveted and piano-hinge-type skin joints and of an aileron slot of the drag characteristics. Any type of surface irregularities at the front spar were found to cause substantial increase in drag.

"Cut-outs in wings or fuselages produce stress concentrations that present a serious problem to the stress analyst. As a partial solution of the general problem, this paper presents formulas for calculating the stress distribution around rectangular cut-outs in axially loaded panels. The formulas are derived by means of the substitute-stringer method of shear-lag analysis" (p. 1).

"An investigation was made to determine a method of measuring fuel-air ratio that could be used for test purposes in flight and for checking conventional equipment in the laboratory. Two single-cylinder test engines equipped with typical commercial engine cylinders were used. The fuel-air ratio of the mixture delivered to the engines was determined by direct measurement of the quantity of air and of fuel supplied and also by analysis of the oxidized exhaust gas and of the normal exhaust gas" (p. 73).

Report presenting an investigation of the effect of changes in the length-beam ratio of flying-boat hulls on resistance and spray. A family of three models of hulls of different length-beam ratios was used and, in order to maintain comparable hull sizes, the plan-form areas of the hulls were made approximately equal by keeping equal products of length and beam. Results regarding resistance, spray, and take-off performance are provided.

Report presenting tests of curved panels of four different thicknesses and with radius-thickness ratios varying from about 150 to infinity. Results are also included from some previous testing.

Report presenting a study devoted to the analysis of the effect of design and operating altitude on the performance of bombers. The primary emphasis is on range performance and charts are presented with range as a function of wing loading, power loading, and design altitude. Results regarding the range at maximum L/D, range at constant power, and performance charts are provided.

Report presenting an investigation of the effect of direction of propeller rotation on the dynamic lateral stability characteristics of a twin-engine airplane model equipped with single vertical tails of three different sizes. The effects of flap deflection and amount of power were also studied. The most satisfactory lateral-stability characteristics of the model in flight were encountered for the model with large vertical-tail areas.

Report presenting a study of several ducts installed in the wings of a model of a conventional single-engine pursuit airplane in the full-scale tunnel to determine the influence of inlet design and cooling-air flow on the pressure losses within the duct and on the aerodynamic characteristics of the airplane. Large differences in the total pressure at the radiator occurred as a result of variations in the inlet-velocity ratio, the lift coefficient, the shape and position of the inlet, the slope of the diffuser axis, and propeller operation.

Report presenting an estimate of the flying qualities of a twin-engine patrol airplane from wind-tunnel test results in comparison with flight observations as a possible guide in determining changes which would be necessary to improve these qualities. Results regarding the longitudinal and lateral stability and control of this airplane are provided.

Report presenting pressure-distribution measurements on a scale model of the Douglas XA-26 airplane as obtained in the 19-foot pressure tunnel. The measurements were made on the spinner-cowl-nacelle assembly and the fuselage for a range of angles of yaw and angles of attack.

"Theoretical and experimental investigations of the effect of frictional heat on the rate of heat transmission at high fluid velocities are briefly reviewed. On the basis of these investigations, calculations are made which show that the use of the stagnation temperature of the cooling air as the effective temperature for heat transfer in an aircraft heat exchanger is sufficiently accurate" (p. 1).

Report summarizing information of the types of material that can be used for lightning conductors on nonmetallic aircraft and reporting the results of experiments on the more important properties of the materials.

Report presenting an investigation to determine the effect of acid on the strength and aging properties of various types of resin bonds for plywood. The pH values of the birch plywoods, flexural and impact strengths before and after aging of birch plywoods bonded with urea-formaldehyde resins and phenolic resins, and delamination properties of birch plywoods bonded with each type of resin are provided.

Report presenting the basic methods of theoretically calculating the critical stress for plates with elastically restrained edges. Design charts for various types of sections and columns and critical stress for flat plates and curved sheets are provided.