Report presenting testing of rectangular Clark-Y biplane cellules with zero and -0.25 stagger, the gap equal to the chord, and 0 degrees decalage were tested on the NACA spinning balance in the 5-foot vertical tunnel.

Three rectangular monoplane wings having rounded tips were tested on the N.A.C.A. spinning balance in the 5-foot vertical wind tunnel. The airfoil sections used were the N.A.C.A. 0009, 23018, and 6718. The aerodynamic characteristics of the models and a prediction of the angles of sideslip for steady spins are given. There is included an estimate of the yawing moment that must be furnished by parts of the airplane to balance the inertia couples and wing yawing moments for spinning equilibrium. The predicted angles of sideslip and yawing moments required for spinning equilibrium for a Clark Y wing with the same form are included for comparison.

Four N.A.C.A. 23012 wings were tested at several angles of yaw in the N.A.C.A. 7- by 10-foot wind tunnel. All the wings have rounded tips and, in plan form, one is rectangular and the others are tapered 3:1 with various amounts of sweep. Each wing was tested with two amounts of dihedral and with partial-span split flaps. The coefficients of lift, drag, and pitching moment are given for all the models at zero yaw. The coefficients of rolling moment, yawing moment, and side force are given for the rectangular wing at all values of yaw tested. The rate of change in the coefficients with angle of yaw is given in convenient form for stability calculations.

Note presenting testing of an N.A.C.A. 23012 rectangular wing with rounded tips in combination with a fuselage of circular cross section at several angles of yaw in the NACA 7- by 10-foot wind tunnel. The model was tested as a high-wing, a midwing, and a low-wing monoplane; for each wing location, tests were made with two amounts of dihedral and with partial-span split flaps. Results regarding the wing and fuselage, fin and fuselage, and wing, fuselage, and fin are provided.

"The tests described in this report were made as part of an investigation of the spinning characteristics of the F4B-2 airplane conducted at the request of the Bureau of Aeronautics, Navy Department" (p. 1).

Tests were made with the spinning balance in a 5-foot wind tunnel to study the effect of stabilizer location upon the pitching and yawing moments given by the tail surfaces in spinning attitudes. The tests revealed that the horizontal surfaces, when in a normal location, seriously reduced the effectiveness of the fin and rudder, particularly at angles of attack of 50 degrees or more. The tests also revealed that a more forward or more rearward location gave no consistent or decided improvement; that a lower location greatly increased the shielding so that the yawing moment from the combination was in general less than that given by the bare fuselage; and that a higher location decreased the shielding and gave a favorable interference effect, particularly at the high angles of attack. Additional results regarding the stabilizer and the elevator are given.

From Summary: "The investigation described in this report was made to determine the effectiveness of floating wing-tip ailerons as an airplane control in the spin. In these tests the ailerons, not being balanced, were set parallel to the axis of rotation, which is probably very nearly the attitude that balanced floating ailerons would assume in a spin. Rolling - and yawing moment coefficients are given as measured for the model with and without the ailerons, and computed values are given for the ailerons alone."

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 investigation described in this report is concerned with the changes in the aerodynamic characteristics of an airfoil which are produced by a gauze-covered suction slot, located near the leading edge, and connected by an air passage to a split flap at the trailing edge. The tests were conducted at the Langley Memorial Aeronautical Laboratory. At the larger values of lift coefficient where the action of the slot might be expected to be most effective, the pressure differences were such that the air flowed out of the slot rather than in through it, and in consequence, the maximum lift coefficient was decreased" (p. 1).

"The reflection and transmission coefficients have been determined for a plane sound wave incident on a slotted wall separating two moving fluid streams. This acoustics problem is related to the aerodynamic problem of determining the tunnel-wall interference on an oscillating airfoil in a slotted-throat wind tunnel in that the same boundary condition is involved with one of the two streams at the boundary having zero velocity. In the analysis the wall with discrete slots is replaced by an equivalent homogeneous boundary" (p. 1).

Report presenting an investigation of the effect of diffuser performance of the passage curvature of two vaneless diffusers designed with a 6 degree equivalent-cone divergence angle along a logarithmic-spiral path in combination with two mixed-flow impellers. The peak of overall adiabatic efficiency is compared with the corresponding diffuser efficiency. Results regarding the variation of diffuser efficiency with load-coefficient parameter and peak overall adiabatic efficiencies and corresponding diffuser efficiencies of the two compressors are provided.

Note presenting an investigation of the effect of open circular holes on the tensile strength and elongation of sheet specimens of magnesium alloy AM-C52S in both the annealed and hard-rolled condition. Tests were made to study the effect of variable ratio of hole diameter to total specimen width and the effect of spacing and arrangement of the holes.

Note presenting tests at high speeds to determine the drag of models, simulating propeller shanks, in the form of a circular cylinder and three airfoils with the rear 25 percent chord cut off. The results indicated that the drag of the airfoils was lower than that of the cylinder over the Mach number range investigated.

Report presenting an experimental and analytical investigation of the flutter of sweptback cantilever wings. The experiment employed groups of wings swept back by rotating and by shearing, with a range of angles of sweep tested. Comparison with experimental results indicated that the analysis is generally satisfactory for the main effects of sweep.

Report presenting a combination of two previously published reports with an extension of the data to cover properties of fuels up to temperatures as high as 400 degrees Fahrenheit.

"Results are presented of compressive stress-strain tests of titanium sheet at temperatures from room temperature up to 800 degrees Fahrenheit, exposure times of 1/2 to 2 hours, and strain rates of 0.002 to 0.006 per minute. The results show that titanium has favorable compressive properties, comparable to those in tension, up through 800 degrees Fahrenheit. Marked anisotropy in compression was also noted" (p. 1).

"An experimental determination of the critical bending moment of a box beam stiffened by posts is described and discussed. The experimental buckling load is in good agreement with that given by theory. Since appreciable distortion of the beam cross section occurred before the buckling load was reached, modification of post construction by the use of several ribs may be necessary for maintenance of the rectangular shape of the cross section" (p. 1).

Note presenting temperatures of a turbosupercharger rotor measured in flight for a variety of conditions by thermocouples, the leads of which were brought away from the turbine by means of rotating slip rings and stationary brushes. A consistent and almost linear relation was shown between turbine temperature at the outer edge of the rim and the effective exhaust-gas temperature at the surfaces of the blades on three successive flights at cruising power.

Note presenting testing of geometrically related structural joints representing typical skin-stringer cross sections under radiant heating to simulate the effects of aerodynamic heating. The presence of an interface was found to have a significant effect on the temperature distribution in all geometries tested and thus must be considered in temperature calculations. Interface conductance values were computed for each of the 15 fabricated specimens.

Note presenting testing of twenty-seven structural joint specimens of 2024-T3 and 2024-T4 aluminum alloy consisting of a T-stringer riveted to a 10- by 10-inch skin surface under simulated aerodynamic heating with no external loading applied. Rivet size and pitch were found to influence the conductance but the rivet materials tested had no observable effect.

Note presenting tests conducted to determine the factors influencing the thermal conductance across the interference between 75S-T6 aluminum-alloy and AISI Type 416 stainless-steel structural joints. The type of joints investigated included: bare metal-to-metal contact, contact surfaces coated with zinc-chromate primer, contact surfaces separated by thin foils of good conductors, contact surfaces separated by thin sheets of insulation, contact surfaces joined by strength-giving bonds, and riveted joints. The factors investigated were heat flow, temperature drop, temperature level, and surface condition.

Technical note presenting tests conducted to determine the factors influencing the thermal conductance across the interface formed between stationary plane surfaces of 75S-T6 aluminum-alloy and AISI Type 416 stainless-steel blocks. The types of joints investigated included bare metal-to-metal contact, contact surfaces separated by a good conductor (brass), and contact surfaces separated by a thin sheet of insulation (asbestos). Results regarding the effect of surface roughness, pressure, mean interface temperature, temperature drop, sandwich material, time as a factor in conductance, and effect of test reassembly and interface matching are provided.

"The slip theory of plasticity is applied to the problem of calculating the strains associated with biaxial tension for the case of constant stress ratios and is found to be in better agreement with experiment than the octahedral-shear and maximum-shear theories usually employed to analyze such data" (p. 1).

Note presenting a derivation of a modified form of Donnell's equation for the equilibrium of thin cylindrical shells which is equivalent to Donnell's equation but has certain advantages in physical interpretation and in ease of solution, particularly in the case of shells with clamped edges. The modified equation can be solved for the buckling stresses of curved sheet having either simply supported or clamped edges by established methods essentially equivalent to those in use for flat sheet.