Drag tests at zero lift have been made at Mach numbers from 0.7 to approximately 0.95 in the high speed wind tunnel of the Institute of Aerodynamics, ETH, Zurich, on a group of untapered wings of aspect ratio 3.25, having sweep angles of 0 degree and 35 degrees. For each sweep angle, a series of geometrically similar models was tested at a constant Reynolds number to provide a verification of computed tunnel blocking corrections. Tests were also made for wings having thickness ratios of 0.09 and 0.12 and the results compared with results predicted by von Karman's similarity law.

Report presenting an investigation to measure the flying qualities of a high-performance personal-owner airplane to investigate the possible causes of instrument flying accidents with that type of aircraft. Testing indicated that the lack of aerodynamic stall warning and rapid roll-off at the stall could contribute to stall-spin accidents with high-performance personal-owner aircraft. Results regarding the handling qualities and the control under instrument flying conditions are provided.

"By use of an approximate equation for the wave drag of slender bodies of revolution in a supersonic flow field, the optimum shapes of certain boattail bodies are determined for minimum wave drag. The properties of three specific families of bodies are determined, the first family consisting of bodies having a given length and base area and a contour passing through a prescribed point between the nose and base, the second family having fixed length, base area, and maximum area, and the third family having given length, volume, and base area. The method presented is easily generalized to determine minimum-wave-drag profile shapes which have contours that must pass through any prescribed number of points" (p. 1).

Buffet boundaries, buffeting-load increments for the stabilizers and elevators, and buffeting bending-moment increments for the stabilizers and wings as measured in gradual maneuvers for a jet-powered bomber airplane are presented. The buffeting-load increments were determined from strain-gage measurements at the roots or hinge supports of the various surfaces considered. The Mach numbers of the tests ranged from 0.19 to 0.78 at altitudes close to 30,000 feet. The predominant buffet frequencies were close to the natural frequencies of the structural components. The buffeting-load data, when extrapolated to low-altitude conditions, indicated loads on the elevators and stabilizers near the design limit loads. When the airplane was held in buffeting, the load increments were larger than when recovery was made immediately.

Report presenting the results of an experimental investigation of the downwash and longitudinal stability characteristics of a semispan, triangular-wing airplane model with a horizontal tail. Lift, drag, and pitching-moment data re presented for the wing-fuselage combination. Results indicated that the model with the tail on or below the wing-chord plane possessed satisfactory stability characteristics throughout the test range of lift coefficient.

From Summary: "Experimental force, moment, and center-of-pressure variations for a large number of bodies of revolution have been compared with the calculated characteristics based on the approximate theory developed in NACA-RM-A9I26. The bodies varied in fineness ratio from 4.5 to 21.1, from blunt unboattailed bodies to airship hulls, and the experimental results are given for widely varying Mach number ranges of angle of attack. It is shown that the lift and drag characteristics are fairly accurately predicted by the theory but that the actual center of pressure is more rearward than the theory indicates."

From Summary: "The observed flow field about slender inclined bodies of revolution is compared with the calculated characteristics based upon potential theory. The comparison is instructive in indicating the manner in which the effects of viscosity are manifest. Based on this and other studies, a method is developed to allow for viscous effects on the force and moment characteristics of bodies. The calculated force and moment characteristics of two bodies of high fineness ratio are shown to be in good agreement, for most engineering purposes, with experiment."

"A method is presented for the computation and graphic representation of a series of possible turbine designs for any specific application. The use of a preliminary design chart is suggested for determining the number of stages and the effects of exit whirl and annular-area divergence on possible configurations. A specific design chart can then be made to aid in the study of the relations between turbine radius ratio, diameter, and significant design parameters such as Mach numbers, turning angles, and blade root stresses" (p. 1).

Note presenting an experimental investigation in which measurements were made of the turbulent boundary layer of a two-dimensional unswept wing and a comparable wing swept 45 degrees. The results indicate the applicability of simple sweep theory for determining turbulent boundary-layer growth on the swept wing for a lift coefficient of zero.

Report presenting charts to provide a convenient means for obtaining the derivatives of rotor resultant force, rotor pitching amount about the helicopter center of gravity, and rotor torque with respect to rotor angle of attack, forward speed, rotor speed, and collective pitch.

"Charts giving the compressive-buckling stress coefficients for sheet panels of a shape occurring in swept-wing plan forms are presented. The panels are assumed to be a part of a continuous flat sheet divided by nondeflecting supports into parallelogram-shaped areas. The stability analysis was performed by the energy method and the results show that, over a wide range of panel aspect ratio, such panels are decidedly more stable than equivalent rectangular panels of the same area" (p. 1).

Memorandum presenting flight tests conducted on two straight-wing jet airplanes of generally similar configuration, one exhibiting a diving tendency and the other a climbing tendency, in order to investigate the cause for the particular type of behavior of each airplane at high Mach numbers. The results showed that the diving tendency experienced by the one airplane was due to the predominant effect of an increased angle of attack of the horizontal tail.

This report presents the results of flight measurements of longitudinal stability and control characteristics made on a swept-wing jet aircraft to determine the origin of the pitch-up encountered in maneuvering flight at transonic speeds. For this purpose measurements were made of elevator angle, tail angle of attack, and wing-fuselage pitching moments (obtained from measurements of the balancing tail loads).

From Summary: "Flight tests were conducted on a straight-wing fighter-type jet airplane to investigate the lateral-control characteristics associated with a wing-dropping tendency encountered at high subsonic Mach numbers. The chief factors found to account directly for the wing-dropping tendency were a progressive reduction in aileron-control effectiveness with increasing Mach number, and an increase in effective dihedral above a Mach number of 0.8 which made the lateral trim particularly sensitive to small changes in sideslip angle."

The altitude-ignition limits of a condenser-discharge ignition system installed on a turbojet engine were determined at a flight Mach number of 0.6 using 1.1-pound Reid vapor pressure fuel. Ignition was possible up to an altitude of 55,000 feet with 4.8 joules per spark and 6 sparks per second.

Effects of air-cooling turbine rotor blades on performance of a turbojet engine were calculated for a range of altitudes from sea level to 40,000 feet and a range of coolant flows up to 3 percent of compressor air flow, for two conditions of coolant bleed from the compressor. Bleeding at required coolant pressure resulted in a sea-level thrust reduction approximately twice the percentage coolant flow and in an increase in specific fuel consumption approximately equal to percentage coolant flow. For any fixed value of coolant flow ratio the percentage thrust reduction and percentage increase in specific fuel consumption decreased with altitude. Bleeding coolant at the compressor discharge resulted in an additional 1 percent loss in performance at sea level and in smaller increase in loss of performance at higher altitudes.

Note presenting an investigation of the loss of strength of tensile specimens of polymethyl methacrylate as a result of stress-solvent crazing at 23 degrees Celsius and 50-percent relative humidity. the materials tested were commercial cast polymethyl-methacrylate sheets of both heat-resistant and ordinary grades from each of two manufacturers.

Report presenting an investigation of the effects of many of the parameters significant to wing flutter on several untwisted rotating models to determine their significance with respect to stall flutter of propeller blades. The parameters included torsional stiffness, section thickness ratio, sweepback, length-chord ratio, section center-of-gravity location, blade taper, Mach number, and fluid density. Results regarding the considerations on method of presentation, experimental data and discussion, some possible applications, and a comparison of experiment with classical-flutter theory are provided.

This report is a compilation of many of the pertinent research data acquired by the National Advisory Committee for Aeronautics on fuel performance in piston engines. The original data for this compilation are contained in many separate NACA reports which have in the present report been assembled in logical chapters that summarize the main conclusions of the various investigations. Complete details of each investigation are not included in this summary; however, such details may be found, in the original reports cited at the end of each chapter.

"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).

Fuels having Reid vapor pressures of 6.3 and 1.0 pounds per square inch were investigated in a tail-pipe burner on an axial-flow-type turbojet engine at a simulated flight Mach number of 0.6 and altitudes from 20,000 to 45,000 feet. With the burner configuration used in this investigation, having a mixing length of only 8 inches between the fuel manifold and the flame holder, the low-vapor-pressure fuel gave lower combustion efficiency at a given tail-pipe fuel-air ratio. Because the exhaust-nozzle area was fixed, the lower efficiency resulted in lower thrust and higher specific fuel consumption. The maximum altitude at which the burner would operate was practically unaffected by the change in fuel volatility.

Report discussing the results of an investigation to determine the stability and control characteristics of a flying model of an unswept-wing vertically rising airplane. Information about stabilization, maneuverability, rolling motions, and landings is provided.

Report presenting an investigation to determine the stability and control characteristics of a vertically rising airplane model. Results of preliminary hovering flight tests are made in still air, away from the interference effects of the ground and side walls, and with normal airplane-type controls operating in the slipstream.

Report presenting an investigation of water landings in the impact basin with a model with a flat rectangular planing surface, a pulled-up bow, and a simulated landing wheel. Runs were made at several wave conditions, trim ranges, flight-path angles, and beam loadings. The results were found to be applicable in predicting loads and motions exhibited by a flat rectangular ski during impact with a water surface.