Memorandum presenting a general wave equation derived governing the propagation of sound in a stratified moving medium, the velocity of which varies only along one coordinate. A simplified equation is adopted which is satisfactory for the present application.

"Drag characteristics of a series of related conical and circular-arc afterbodies are presented for Mach numbers from 0.6 to 1.3. Drag was obtained from pressure measurements on the boattail and solid base. The boattail angles tested ranged from 0 degrees to 45 degrees for ratios of base diameter to maximum body diameter ranging from 0 to 1.0" (p. 1).

"A number of noise-suppression nozzles were tested on full-scale engines. In general, these nozzles achieved noise reduction by the mixing interference of adjacent jets, that is, by using multiple-slot-nozzles. Several of the nozzles achieved reductions in sound power of approximately 5 decibels (nearly 70 percent) with small thrust losses (approx. 1 percent). The maximum sound-pressure level was reduced by as much as 18 decibels in particular frequency bands" (p. 1249).

Tests were performed in the Langley Unitary Plan wind tunnel to determine the drag and static longitudinal and lateral stability and control characteristics of a 1/20-scale model of the McDonnell F4H-1 airplane at Mach numbers of 1 57, 1 87, 2.16, and 2.53. This is the second phase in a series of tests performed on this model. The Reynolds numbers for these tests, based on the mean aerodynamic chord of the wing, are 1.446 x 10 (exp 6), 1.269 x 10 (exp 6), 1.116 x 10 (exp 6), and 0.714 x 10 (exp 6) at Mach numbers of 1.57, 1.87, 2.16, and 2.53, respectively.

A blade design study is presented for a two-stage air-cooled turbine suitable for flight at a Mach number of 2.5 for which velocity diagrams have been previously obtained. The detailed procedure used in the design of the blades is given. In addition, the design blade shapes, surface velocity distributions, inner and outer wall contours, and other design data are presented. Of all the blade rows, the first-stage rotor has the highest solidity, with a value of 2.289 at the mean section. The second-stage stator also had a high mean-section solidity of 1.927, mainly because of its high inlet whirl. The second-stage rotor has the highest value of the suction-surface diffusion parameter, with a value of 0.151. All other blade rows have values for this parameter under 0.100.

Report presenting an investigation at transonic speeds to determine the effects of a sonic propulsive jet on the aerodynamic characteristics of the body from which it issues. A variety of afterbody shapes and their pressure distributions are described. Correlations are also drawn between certain characteristics of the afterbody and the effect of temperatures.

Report presenting a two-stage air-cooled turbine configuration and its velocity diagrams for use in the design of blade shapes for a set of engine conditions suitable for flight at Mach number 2.5. The method used to determine the velocity diagrams was one in which the turbine frontal areas and rotor hub inlet and outlet velocities were minimized by varying the hub-tip ratio, turbine- to compressor-tip-diameter ratio, and the work split between the first and second stages.

At the design speed of a two-stage counterrotating compressor, an overall average pressure ratio of 4.3 was obtained at a specific weight flow of 27.2 pounds per second per square foot frontal area with an adiabatic efficiency of 0.75. Preliminary tests indicate that a weight-flow mismatching exists between the two rotors that causes the first rotor to operate at less than peak efficiency at design speed. At lower speeds, the first stage was forced to operate in the stalled region in single-stage tests. With the second rotor installed, no periodic rotating stall was observed, although random fluctations of similiar magnitude were noted.

Double-ramp side inlet with combinations of fuselage, ramp, and throat boundary layer removal.

Report presenting pressure-drag coefficients and the changes in these coefficients with mass-flow ratio, which have been measured in tests of six open-nose conical cowls at an angle of attack of 0 degrees. Testing occurred in the Ames 8 by 8-inch supersonic wind tunnel at a range of Mach numbers. Results regarding pressure distributions, change in cowl pressure drag with mass-flow ratio, cowl pressure drag at a given mass-flow ratio, and changes in cowl pressure drag with mass-flow ratio as a function of Mach number are provided.

Report presenting the tendencies of 14 different fuels and three fuel blends to produce high-frequency oscillatory combustion (screaming) in a 200-pound-thrust, water-cooled, liquid-oxygen-fuel rocket engine. The fuels, in order of increasing screaming tendency, were hydrazines, branched-chain paraffins, aromatics, and amines, and straight-chain paraffins. Results regarding screaming tendency and screaming amplitude are provided.

Memorandum presenting an investigation to devise an air-cooled turbine blade which eliminated the difficulties encountered with brazing in air-cooled-blade fabrication. Techniques were developed for casting air-cooled blades with a large number of relatively small cooling passages near the airfoil surface; two such blades of HS-21 material were operated in a turbojet engine modified for air cooling. Results regarding the heat-transfer characteristics, stress and durability results, and evaluation of cast-cored-blade potential are provided.

Report presenting the zero-lift drag of several wings obtained at supersonic Mach numbers in free flight with rocket-propelled models. The wings tested all had the same exposed area, mounted on the same basic body configuration, and had one of four different types of wings.

Report discusses the results of an investigation of a model of a wing of 45 degree sweepback and aspect ratio 6 to determine the aerodynamic characteristics and suction requirements for boundary-layer control by means of area suction applied to trailing-edge flaps. Various flap spans and flap deflections were tested. The measured values of the coefficients were compared to the calculated values.

Report presenting a blade-vibration and rotating-stall survey on a modified version of a production turbojet engine with a 13-stage axial-flow compressor with a design pressure ratio of 7 and an air flow of 120 pounds per second. This testing was carried out due to the problems rotating stall can cause with both experimental and production axial-flow compressors. Results regarding the rotating-stall patterns, rotor-blade vibrations, radial and axial strength of rotating stall, and maximum rotating-stall speed are provided.

Report presenting the effect of adjusting compressor inlet-guide-vane angle on overall compressor performance, stage performance, engine thrust, and specific fuel consumption in a 7000-pound-thrust turbojet engine. Data was obtained at several angles and demonstrated that increasing the guide-vane angle decreased the weight flow at the higher compressor speeds. It had no effect on stage performance other than at the first stage, where it reduced maximum flow, pressure, and temperature coefficients.

Report discussing methods, advantages, and disadvantages of locating rotating heat exchangers ahead of, within, and behind the main engine compressor. Heat rejection should occur at the compressor discharge for best engine performance. Results regarding turbojet-engine performance, turboprop-engine performance, and a comparison of engine performance with liquid- and air-cooling are provided.

Report presenting a highly loaded transonic rotor which was designed, built, and tested as part of a two-stage counterrotating-compressor research program. The design conditions were chosen to explore the upper limits of loading and Mach number for the transonic unit. The complete rotor design procedure is presented as well as the recorded stall traces and techniques for obtaining the data.

"The transient motion in angles of attack and sideslip during a constant rolling maneuver has been analyzed. Simplified expressions are presented for the determination of the pertinent modes of motion as well as the modal coefficient corresponding to each mode. Calculations made with and without the derivatives for side force due to sideslip and lift-curve slope indicate that although these derivatives increase the total damping of the system they do not markedly affect the transient motion" (p. 131).

Report presenting a J47-25 engine instrumented with thermocouples and operated under steady-state and transient-conditions in an altitude test stand to determine the operating temperatures at altitude in the turbine section of a turbojet engine. Results regarding the temperature effects and transient operation are provided.

"A linear stability analysis and flight-test investigation has been performed on a rolleron-type roll-rate stabilization system for a canard-type missile configuration through a Mach number range from 0.9 to 2.3. This type damper provides roll damping by the action of gyro-actuated uncoupled wing-tip ailerons. A dynamic roll instability predicted by the analysis was confirmed by flight testing and was subsequently eliminated by the introduction of control-surface damping about the rolleron hinge line" (p. 1).

"The external wave drag of bodies of revolution moving at supersonic speeds can be expressed either in terms of the geometry of the body, or in terms of the body-simulating axial source distribution. For purposes of deriving optimum bodies under various given conditions, it is found that the second of the methods mentioned is the more tractable. By use of a quasi-cylindrical theory, that is, the boundary conditions are applied on the surface of a cylinder rather than on the body itself, the variational problems of the optimum bodies having prescribed volume or caliber are solved" (p. 131).

Report presenting results from a limited flight program to obtain information on airplane response and actual rates and amounts of control motion used by service pilot in performance of squadron operational training. Results regarding control deflection, control rates, airplane angular velocities, airplane angular accelerations, angle of attack and angle of sideslip, airplane load factors, and airspeed and altitude are provided.

"An experimental investigation has been conducted to determine the stability and control characteristics of a 0.13-scale free-flight model of the Convair XFY-1 airplane during take-offs and landings in steady winds. The tests indicated that take-offs in headwinds up to at least 20 knots (full scale) will be fairly easy to perform although the airplane may be blown downstream as much as 3 spans before a trim condition can be established. The distance that the airplane will be blown down-stream can be reduced by restraining the upwind landing gear until the instant of take-off" (p. 1).