From Summary: "The data from previous NACA pressure-distribution investigations of plain flaps and tabs have been analyzed and are presented in this paper in a form readily applicable to the problems of control-surface design. The experimentally determined variation of aerodynamic parameters with flap chord and tab chord are given in chart form and comparisons are made with the theory. With the aid of these charts and the theoretical relationships for a thin airfoil, the aerodynamic characteristics for control surfaces of any plan form with plain flaps and tabs may be determined. A discussion of the basic equations of the thin-airfoil theory and the development of a number of additional equations that will be helpful in tail design are presented in the appendixes. The procedure for applying the data is described and a sample problem of tail design is included."

Note presenting computations made to determine the effects of some airplane design trends on the fin area and the dihedral angle required for lateral stability. The specific factors studied were wing loading, moments of inertia in roll and yaw, wing chord, and tail length. The results of the computations are presented in the form of diagrams of variations of fin area with dihedral angle for neutral stability.

"The arrangement of the parts and the installation and control problems of the two-stage mechanically driven superchargers for aircraft engines are discussed. Unless an entirely new form of supercharging is developed, there will be a definite need for a two-stage centrifugal supercharger. It is shown that the two-stage mechanically driven supercharger itself is a comparatively simple device; the complications arise from the addition of inter-coolers and controls" (p. 1).

From Introduction: "This paper deals only with the aerodynamics of the fan proper and demonstrates the manner in which the radial distribution of axial velocity of fluid through a fan is governed by geometry of the fan itself."

"The effects of power on the stability and the control characteristics of an airplane are discussed and methods of analysis are given for evaluating certain dynamic characteristics of the airplane that are not directly discernible from wind-tunnel tests alone. Data are presented to show how the characteristics of a model tested in a wind tunnel are affected by power. The response of an airplane to a rolling and a yawing disturbance is discussed, particularly in regard to changes in wing dihedral and fin area" (p. 1).

The effects of power on the stability and the control characteristics of an airplane are discussed and methods of analysis are given for evaluating certain dynamic characteristics of the airplane that are not directly discernible from wind tunnel tests alone. Data are presented to show how the characteristics of a model tested in a wind tunnel are affected by power. The response of an airplane to a rolling and a yawing disturbance is discussed, particularly in regard to changes in wing dihedral and fin area. Solutions of the lateral equations of motion are given in a form suitable for direct computations. An approximate formula is developed that permits the rapid estimation of the accelerations produced during pull-up maneuvers involving abrupt elevator deflections.

"Concurrent tests were performed on a 1/16 and a 1/20 scale model (wing spans of 2.64 and 2.11 ft. respectively) of a modern low wing monoplane in the NACA 15 foot free-spinning wind tunnel. Results are presented in the form of charts that afford a direct comparison between the spins of the two models for a number of different conditions. Qualitatively, the same characteristic effects of control disposition, mass distribution, and dimensional modifications were indicated by both models" (p. 1).

Note presenting testing performed on scale models of a modern low-wing monoplane in the 15-foot free-spinning wind tunnel. Results are presented in the form of charts that afford a direct comparison between the spins of the two models for a number of different conditions. The results indicate that, within the range of Reynolds numbers used in the present investigation, such factors as difficulty of ballasting and testing are more important in determining proper model size than the changes in scale effect likely to result from the use of different sizes of models.

From Introduction: "The ideas developed in this paper are presented as a means of saving the designer's time and as a method of reduction of control-system friction by an accurate calculation of pulley-axis angles without the errors and difficult checking incident to any graphical method."

Note presenting an investigation to determine the performance of a small airplane with two Continental A-75 air-cooled engines enclosed in the wings. The object of the tests was to determine the quantity of air and the pressure difference required for satisfactory cooling of the engine at sea level and at altitude. The engine could be cooled satisfactorily at sea level with wide-open throttle and maximum-power mixture with a pressure difference of 4.5 inches of water and 1.06 pounds of cooling air per second.

"The pitching and the yawing moments of a vee-type and a conventional type of tail surface were measured. The tests were made in the presence of a fuselage and a wing-fuselage combination in such a way as to determine the moments contributed by the tail surfaces" (p. 1).

Report presenting testing of specimens cut from a specially extruded I-beam of 17S-T aluminum alloy with one flange wider than the other under axial compression. Only the two longest specimens failed as columns, while the shorter ones failed by local buckling. The agreement between experimental and calculated values of critical stress can be improved by considering the effect of restraint at the loaded edges of the web and adopting a more accurate buckling treatment beyond the elastic range.

Note presenting testing of two series of stiffened flat sheet specimens tested under edge compression using various end conditions: round ends, flat ends, and continuous panels. The specimens consisted of aluminum-alloy flat sheet stiffened by three hat-shaped extruded aluminum-alloy stiffeners. The results indicated that the length of the specimen has an insignificant effect on the ultimate compressive load.

"Compressive tests were made of two series of stiffened circular cylindrical shells under axial load. All the shells were 16 inches in diameter by 24 inches in length and were made of aluminum-alloy sheet curved to the proper radius and welded with one longitudinal weld. The ratios of diameter to thickness of shell wall in the two series of specimens were 258 and 572" (p. 1).

"Tensile and compressive properties were determined of specimens cut from the fins and the main bodies of two different extruded shapes of 24S-T aluminum alloy. The specimens from the fins as compared with those from the main body of the section showed: tensile strengths from 5000 to 10,000 pounds per square inch lower; tensile yield strengths and compressive yield strengths 4000 to 9000 pounds per square inch lower. The compressive yield strength values for any given location in the cross sections were about 1000 to 6000 pounds per square inch lower than the tensile strength values for the same location" (p. 1).

"The results of tests of 65 specimens of aluminum-alloy channel sections are graphed for stresses due to axial and bending loads as functions of the ratio of length of specimen to its radius of gyration, and from these data a suggested design chart is derived that is suitable for ready use" (p. 1).

Report presenting an investigation of the lateral motion resulting from a disturbance of the type produced by asymmetric loss of thrust for a hypothetical average airplane equipped with an automatic pilot. Plots of the resultant motion and various modes that constitute the motion are presented for fixed controls and for various amounts of autopilot.

"It is shown that a simple correction for the chord of a finite wing can be deduced from the three-dimensional potential flow around an elliptic plate. When this flow is compared with the flow around a section of an endless plate, it is found that the edge velocity is reduced by the factor 1/E, where E is the ratio of the semiperimeter to the span. Applying this correction to the circulation brings the theoretical lift into closer agreement with experiments" (p. 1).

"Problems involved in the stability and control of tailless airplanes are discussed. Such factors as the location of the aerodynamic center and its effect on the longitudinal stability, longitudinal trim with high-lift devices, the effects of various changes in the shape of the wing on lateral stability, and the effects of nacelles are covered. It appears that sufficient stability and controllability can be secured without sweepback" (p. 1).

Note presenting the end-plate effect of the horizontal-tail surface on the vertical-tail surface as theoretically studied by derivation of the flow corresponding to the condition of minimum induced drag and by solution of the usual lifting-line equations. The results obtained by the two methods were considerably different, indicated that the condition derived is not a close approximation to the actual condition.

"A study is presented of ground effect as applied to the lifting airscrew of the type used in modern gyroplanes and helicopters. The mathematical analysis of the problem has been verified by tests made of three rotor models in the presence of a large circular "ground plane." The results of the study are presented in the form of convenient charts" (p. 1).

"Tests were made on 18 shear panels of 24S-T aluminum alloy to verify the dependence of the ultimate stress on the degree of development of the diagonal-tension field. Tests were made on two thicknesses of sheet with the sheet either clamped between the flange angle or riveted to the outside of the angles" (p. 1).

Report presenting testing of three-blade, adjustable-pitch counterrotating tandem model propellers adjusted to absorb equal power at maximum efficiency of the combination. The aerodynamic characteristics were determined for a variety of blade-angle settings and diameter spacings. At maximum efficiency, the tandem propellers absorb about double the power of the three-blade propellers and about 8 percent more power than six-blade propellers with the pitch of the forward propeller of the tandem combination.

"An investigation was made in the NACA 7- by 10-foot wind tunnel to determine the effect of slot-lip location on the aerodynamic section characteristics of an NACA 23012 airfoil with a 30-percent-chord slotted flap. Tests were made with slot lips located at 90 and 100 percent of the airfoil chord and with two different flap shapes. The results are compared with a slotted flap previously developed by the National advisory Committee for Aeronautics with a slot lip located at 83 percent of the airfoil chord. The extension of the slot lip to the rear increased the section lift and pitching-moment coefficients" (p. 1).