"Strain measurements were made on the compression side of two box beams with corrugated aluminum-alloy covers loaded to failure. Angles formed from sheet were used for corner flanges in beam 1; whereas extruded angles were used in beam 2. Failure in each beam occurred in the corner angle at a stress that was above the compressive yield stress for the material" (p. 1).

Report discusses the significance of alkylate-replacement values and to illustrate methods of estimating these values. Equations expressing alkylate-replacement values and the estimated effect on engine performance resulting from replacement of alkylate is discussed and test data is provided in F-3 and F-4 laboratory engines. The researchers found that "alkylate-replacement value depends not only upon the rating of the fuel component that is replacing the alkylate but also upon the ratings of the alkylate and the base fuel."

Methods are given of determining the potential flow plast an arbitrary cascade of airfoils and the inverse problem of determining an airfoil having a prescribed velocity distribution in cascade. Results indicated that Cartesian mapping function method may be satisfactorily extended to include cascades. Numerical calculation for computing cascades by Cartesian mapping function method is considerably greater than for single airfoils but much less than hitherto required for cascades.

Report presenting an investigation to determine the permissible increase in engine power by using various internal coolants from the consideration of fuel knock and cylinder cooling. The internal coolants tested were water, 30-70 methyl alcohol-water volume percent mixture, 70-30 methyl alcohol-water volume percent mixture, methyl alcohol, and 80-20 ethyl alcohol-water volume percent mixture.

Report discusses the results of an investigation into the oscillations performed by suspended bodies like trailing airspeed heads and other towed devices. The most violent types of instability observed were found to be caused by unsteady or nonuniform air flow where the cable was lowered from the airplane. No method was found for reducing cable oscillations in short cable lengths, but the degree of stability present was considered satisfactory as long as the suspended body is lowered into a uniform air stream.

Report discusses an investigation into piston and ring friction as compared to total engine friction under natural operating conditions. Several test conditions were explored, including the effect of scuffing and excess cylinder-wall lubrication on friction. A device for measuring ring tensions and an apparatus for transforming pressure-crank angle indicator diagrams into pressure-volume indicator diagrams are also described.

Report presents the results of experiments on the resistance and porpoising characteristics of flying-boat hulls equipped with rectractable planing flaps. The ideal flap-hull combination would have hump-resistance characteristics at least equal to the XPB2M-1 flying boat and much better upper-limit porpoising characteristics with the flap retracted. Three ways that the flaps can be applied to a practical design are discussed.

An investigation was conducted to determine and compare the tensile strength of NACA and conventional machine-countersunk flush rivets of several rivet-head angles and varying countersunk depth. The results of the investigation are presented in the form of curves that show the variation of the tensile strength of the rivet with the ratio of the sheet thickness to the rivet diameter. For the same rivet-head angle and for a given angle of c/d, the NACA rivets developed higher tensile strength than the conventional rivets.

"Strain surveys were made on the stringers reinforcing a D-section box loaded in torsion and restrained from warping at the root. On the basis of the tests, a procedure is suggested for estimating the bending stresses due to torsion that occur near the flange of a D-section box. A similar test of a triangular-section box showed that for such a section there were no significant bending stresses due to torsion, a fact which was also shown theoretically" (p. 1).

"Flights were made in natural icing conditions at the NACA Ice Research Project, Minneapolis, Minn. to test several designs of thermal-electric propeller de-icing blade shoes and a hub-generator design. It was found that a minimum average unit power of 2.5 watts per square inch of blade-shoe area would protect the propeller blades at the test conditions. The most satisfactory blade shoe of the three designs tested extended to the 20-percent-chord point and to 90 percent of the blade radius" (p. 1).

"The relation between the elevator hinge-moment parameters and the control forces for changes in forward speed and in maneuvers is shown for several values of static stability and elevator mass balance" (p. 1). Factors affecting stability positively and negatively are presented and potential modifications to the elevator control system are provided. The amount of solid friction present was found to be one of the greatest predictors of instability.

Report discusses an analysis of the stability of an airplane with ailerons free, with particular attention to the motions when the ailerons have a tendency to float against the wind. Information about the aerodynamic balance of the plane and oscillations that may be encountered are included. The effects of friction in the control system is also explored.

"The design of curved sheet panels to resist shear involves a consideration of several factors: the buckling resistance of the sheet, the stress at which buckling becomes permanent, and the strength which may be developed beyond the buckling limit by tension-field action. Although some experimental as well as theoretical work has been done on the buckling and tension-field phases of this problem, neither of these types of action appears to be very well understood. This report presents the results of the first series of torsion tests of stiffened circular cylinders to be completed in connection with this study at Aluminum Research Laboratories" (p. 1).

Report discusses the variation of surface-ignition temperature with charge density, fuel-air ratio, and surface-ignition advance. Tests on several fuels were conducted on a supercharged CFR engine to determine surface-ignition temperature as a function of the three variables. It was concluded that surface-ignition temperature is not a satisfactory criterion for differentiating between preignition characteristics of different fuels.

Report presenting tunnel-wall corrections for an airfoil of finite thickness and camber in a two-dimensional-flow wind tunnel. The theory takes account of the effects of the wake of the airfoil and of the compressibility of the fluid and is based on the assumption that the chord of the airfoil is small in comparison with the height of the tunnel. The theoretical results are compared with the small amount of low-speed experimental data available and agreement is seen to be satisfactory, even for relatively large values of the chord-height ratio.

"Detailed methods are presented for determining the corrections to results from wind-tunnel tests of three-dimensional models for the effects of the model-support system, the nonuniform air flow in the tunnel, and the tunnel walls or jet boundaries. The procedures for determining the corrections are illustrated by equations and the required tests are discussed. Two general methods that are used for determining and applying the corrections to force tests are discussed" (p. 1).

Report discusses an investigation to determine the aerodynamic section characteristics of an NACA 23021 airfoil with a double slotted flap with a chord 32 percent of the airfoil chord with the flaps at various positions. The maximum section lift coefficient, profile-drag coefficient, flap positioning, and effects of deflecting or removing the lower lip are described.

Report discusses pressure-distribution tests of a plain flap with interchangeable beveled trailing edges on an NACA 0009 airfoil. The flap chord was 30 percent of the airfoil chord and the bevel chords were 15 and 20 percent of the flap chord. The purpose of these tests was to supply pressure-distribution data that may be used for structural and aerodynamic design of horizontal and vertical tail surfaces.

Correlation is established between aerodynamic characteristics of control surfaces in two-dimensional and three-dimensional flow. Slope of lift curve was affected little by overhang and balance-nose shape, but increased by sealing flap-nose gap. Effectiveness of balancing tab was same for sealed plain flap and unsealed overhang flap. Changes in hinge-moment coefficient were diminished by sealing gap. Values measured by three-dimensional flow disagreed with two-dimensional flow values until aspect ratio corrections were made.

Report discussing an investigation of the aerodynamic effects of horn balances with various plan forms and of guards on a horizontal tail surface. Rounding the adjacent horn and stabilizer edges causes negligible changes to aerodynamic effects except for the area moment of the horn. A solid horn guard mounted on the end of the stabilizer was found to increase the rate of change of lift with angle of attack and elevator deflection.

"This report outlines the flight conditions that are usually critical in determining the design of components of an airplane which affect its stability and control characteristics. The wind-tunnel tests necessary to determine the pertinent data for these conditions are indicated, and the methods of computation used to translate these data into characteristics which define the flying qualities of the airplane are illustrated" (p. 1).

Report presenting the results of aerodynamic tests of seven-blade propellers which were considered as a possible arrangement to avoid vibration difficulties. Variations of relative blade angle and rotational speeds of the front and rear components of a six-blade dual-rotating propeller were also investigated.

Report presenting testing in the stability tunnel of two types of spring tab used as balances on a partial-span plain aileron. The tabs were connected to a spring located in the control system so that tab deflection was dependent on the control force.