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 the application of transient theory to the rational determination of dynamic loads on airplane structures during initial landing impact. Simplified procedures are described by which the distribution of the maximum attainable value of the dynamic stresses in the structure may be obtained.

From Summary: "This report suggests a method whereby information on the strength under repeated stresses of aircraft materials or structural parts can be used in conjunction with information on service loadings as a means of comparing alternative designs."

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 the aerodynamic factors upon which the ability to perform the maneuver depends in an attempt to obtain a better understanding of the conditions involved and, if possible, to evolve criterions that may be used during design.

Report on stability and control tests of the Bell P-63 series airplanes. Information about the spin characteristics, lateral control characteristics, longitudinal stability and control characteristics and directional stability and control characteristics is provided. A chronology of testing and detailed description of the airplane and its modifications are also provided.

"The data are presented in coefficient form and include lift, drag, and pitching-moment coefficients of the airfoil-flap comoinations and the normal-force, chord-force, and hinge-moment coefficients of the upper (perforated split) flap and lower (slotted) flap" (p. 1).

Report discussing testing of six airfoil sections for the wing of the Vega XP2V-1 airplane in a smooth condition and with standard leading-edge roughness. Information about the lift, drag, pitching-moment characteristics, and sensitivity to roughness is provided. No airfoil was found to be superior to the others in all categories.

Report presenting comparisons of measured and calculated loads on the wing and horizontal tail in pull-up maneuvers for six airplanes over a range of weights. Good agreement was obtained between calculated and measured loads under certain circumstances, but the agreement in some cases was only fair, which may be attributed to poor quantitative knowledge of the aerodynamic parameters or to violation of the assumptions on which the method is based.

"Data from wind-tunnel measurements of elevator hinge-moment coefficients at high angles of attack are utilized in estimating elevator stick forces in spins. The analysis indicates that elevator forces on several current airplanes will be so high that the pilot will be unable to push the stick to the neutral position. Large nose balances involve danger of the elevator locking in the full-up position" (p. 1).

Report presenting testing in the two-dimensional turbulence tunnel of a model of the tip section of the wing of the XP-63 airplane. Several alterations of the skirts and balance on the internal-balance aileron were tested to obtain various aerodynamic characteristics of the aileron.

Report presenting a calculation of the load over an elliptical wing with 30 degrees sweepback by a method, based on vortex theory, which takes account of the chordwise distributions of lifting area. The theory indicates a 14-percent loss in total lift due to the introduction of sweepback, with the greatest loss taking place at the center of the span.

"Strain-gage tests were made on two box beams loaded to destruction in an attempt to verify the shear-lag theory at stresses beyond the yield point. The test results indicated that the corner-flange stresses can be predicted with a fair degree of accuracy. Collapse of both beams was precipitated by failure of the corner angles at stresses close to the column yield stress of the material" (p. 1).

Report presenting flight tests of a twin-engine midwing attack bomber and a single-engine low-wing fighter, which indicate that both have moderately high effective dihedral but different directional stability and control characteristics. The pilots had a harder time controlling the fighter airplane, while the attack bomber was found to have a higher degree of directional stability and low directional trim forces, which the pilots preferred.

Report presenting an investigation of rudder trim force change with speed and power, rudder force reversals in sideslips, and rudder positions in sideslips and straight flight of a P-40E airplane. Quantitative measurements of the items were made on three other vertical arrangements.

Report presenting tests in the full-scale wind tunnel on 11 single-engine military airplanes to investigate methods for increasing their high speed. Results regarding the power-plant installation, flow characteristics, wings, cockpit canopies, landing gear, and air leakage are provided.

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 investigation of underslung cooling-air ducts in various locations on a model of a typical single-engine tractor airplane in the full-scale tunnel. The report contains the results of tests of two forward underslung ducts. Results regarding pressure recoveries at the radiator, pressures behind the radiator, drag and duct efficiency, and critical speeds are provided.

Report presenting flight tests to determine the longitudinal stability characteristics of a pursuit airplane when flown with and without an experimental bellows-type bob weight. When the weight was installed, the stick-free static stability remained approximately constant irrespective of the shift in center of gravity resulting from a change in fuel quantity in the auxiliary fuselage fuel tank. Although the weight functioned satisfactorily, the performance could have been enhanced by the reduction of the friction in the mechanism.

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 wind-tunnel tests made to determine the aerodynamic characteristics of a scale model of a high-speed bomber with a dual pusher propeller aft of the empennage. Some of the results discussed include longitudinal, lateral, and directional stability and control, the empennage design, and ground effects on the aerodynamic characteristics. The results indicate that this particular airplane has several advantages with regard to stability and control over the conventional-type single-engine airplane configuration.

From Summary: "A pursuit type airplane encountered severe diving moments in high-speed dives which make recovery difficult. For the purpose of investigating these diving moments and finding means for their reduction, a 1/6 scale model of the airplane was tested in the 16-foot high-speed wind tunnel at Ames Aeronautical Laboratory. The test results indicate that up to a Mach number of at least 0.75, the limit of the tests, the dive-recovery difficulties can be alleviated and the longitudinal maneuverability improved by the substitution of a long symmetrical fuselage for the standard fuselage."

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.

Report discussing the results of testing on a flying boat model with an afterbody length-beam ratio of 4.7 to determine its takeoff and landing stability and resistance characteristics.The range of stable trims was smaller than models with a conventional afterbody, but the range of stable positions for the center of gravity was about the same. Landing stability was satisfactory, and the hump resistance and trim is less than a boat with a smaller ratio.