Report presenting results obtained with quiescent fuel-air mixtures and with small diffusion flames, which indicate that combustion efficiencies close to 100 percent were obtained at pressure much lower than those found in turbojet combustors at altitudes of 60,000 feet.

Performance of four experimentally investigated axially symmetric spike-type nose inlets is compared on basis of ram-jet-engine aircraft range and operational problems. At design conditions, calculated peak engine efficiencies varied 25 percent from the highest value which indicates importance of inlet design. Calculations for a typical supersonic aircraft indicate possible increase in range if engine is flown at moderate angle of attack and result in engine lift utilized. For engines with fixed exhaust nozzle, propulsive thrust increases with increasing heat addition in subcritical flow region in spite of increasing additive drag. For the perforated inlet there is a range of increasing total-temperature ratios in subcritical flow region that does not yield an increase in propulsive thrust. Effects of inlet characteristics on speed stability of a typical aircraft for three types of fuel control is discussed.

Report presenting testing of a series of seven 10-percent-thick unswept and untapered airfoils of aspect ratio 8.0 using the wing-flow method at a range of Mach numbers. The most significant characteristic noted was the occurrence of an unstable pitching moment variation with angle of attack for small angles of attack at Mach numbers of 0.85 to 0.90 for all airfoils with a conventional thickness distribution. Results regarding lift characteristics, moment characteristics, and drag characteristics are provided.

Report presenting a theoretical investigation of the lateral stability of a towed high-speed fighter plane using a fighter cruising at supersonic speed at 50,000 feet and a 1000-foot cable. The motion of this configuration was shown to have highly unstable oscillation caused by the towline restraint, but the configuration can be stabilized by choosing the right position for the towline connection and several types of automatic controls.

Report presenting the development of an annular combustor by utilizing the design principles evolved in previous investigations and by making 12 design changes to optimize the altitude performance of the combustor. Three types of fuels were used and the combustion efficiency, pressure losses, and outlet temperature profiles were evaluated.

Report presenting an investigation to determine the low-speed large-scale characteristics of an aspect ratio 3 triangular-wing airplane model. The model consisted of the wing in combination with a fuselage of fitness ratio 12.5, a thin, triangular vertical tail with a constant-chord rudder, and a thin, unswept, all-movable tail.

The results of transonic flight measurements of the longitudinal stability characteristics of the Douglas D-558-II research airplane in the original configuration and with outboard fences mounted on the wings are presented. The levels of normal-force coefficient at which the stability decreases and pitch-up starts have been determined for both airplane configurations at Mach numbers up to about 0.94.

Report presenting engine evaluation tests of twelve sets of cermet turbine blades. The first five runs were similar to previous engine tests, but the remaining ones were modified based on information gained during the first runs.

"Preliminary results of approximately 350 maneuvers of all types performed by a Lockheed F-94B jet interceptor airplane during normal operational training are presented in time-history form and are summarized as maximum load factors, control rates, angular accelerations, and sideslip angles plotted against indicated airspeed. The results were obtained from approximately 350 maneuvers performed by a Lockheed F-94B jet interceptor airplane during squadron operational training" (p. 1).

"An investigation was conducted to determine the effectiveness of a free-jet diffuser in reducing the over-all pressure ratios required to operate a free jet with a large air-breathing engine as a test vehicle. Efficient operation of the free jet was determined with and without the considerations required for producing suitable engine-inlet flow conditions. A minimum operating pressure ration of 5.5 was attained with a ratio of nozzle-exit to engine-inlet area of 1.85" (p. 1).

An analysis of inlet-turbojet-engine matching for a range of Mach numbers up to 2.0 indicates large performance penalties when fixed-geometry inlets are used. Use of variable-geometry inlets, however, nearly eliminates th The analysis was confirmed experimentally by investigating at Mach numbers of 0, 0.63, and 1.5 to 2.0 two single oblique-shock-type inlets of different compression-ramp angles, which simulated a variable-geometry configuration. The experimental investigation indicated that total-pressure recoveries comparable withose attainable with well designed nose inlets were obtained with the side inlets when all the boundary layer ahead of the inlets was removed. Serious drag penalties resulted at a Mach number of 2.0 from the use of blunt-cowl leading edges. However, sharp-lip inlets produced large losses in thrust for the take-off condition. These thrust penalties which are associated with the the low-speed operation of the sharp-lip inlet designs can probably be avoided without impairing the supersonic performance of the inlet by the use of auxiliary inlets or blow-in doors.

Boron and its hydrides offer increased flight range relative to conventional fuels for turbojet engines. Preliminary evaluation has been made of the combustion characteristics and deposition problems resulting from burning diborone in a single, modified J33 combustor. A combustor relatively free of deposits for the limited test conditions has been developed. Three possible methods of alleviating deposits on the turbine blades are reported.

Report presenting an investigation of the low-speed stability and control characteristics of a scale model of the proposed MX-1554A design. It employs a triangular wing and triangular stabilizing surfaces. Results regarding the effect of wing incidence, tail position, fences, and chord extensions on the longitudinal characteristics are provided.

From Summary: "A sturdy stiffener is defined as a stiffener of such proportions that it does not suffer cross-sectional distortion when moments are applied to some part of the cross section. When such a stiffener is attached to one edge of a plate, it will resist rotation of that edge of the plate by means of its torsional properties. A formula is given for the restraint coefficient provided the plate by such a stiffener. This coefficient is required for the calculation of the critical compressive stress of the plate."

Memorandum presenting a study of the spontaneous flammability of pentaborane and pentaborane-3-methylpentane blends. The behavior of the substances in air and in liquid and vapor states was studied. Results regarding conditions under which pentaborane did not ignite and conditions under which pentaborane did ignite are provided.

"Test of 10-foot diameter, four and six blade single-rotating and dual-rotating propellers were conducted in the NACA propeller-research tunnel. The propellers were mounted at the front end of a streamline body incorporating spinners to house the hub portions. The effect of a symmetrical wing mounted in the slipstream ranged from 20 degrees to 65 degrees setting corresponds to airplane speeds greater than 500 miles per hour. The results indicate that dual-rotating propellers were from 0 to 6 percent more efficient than single-rotating ones; but, when the propellers operated in the presence of a wing, the gain was reduced by about one-half" (p. 319).

The results of fuel-air ratio and temperature surveys made in the flame stabilizing zone of a 16-inch ram-jet combustor indicated that the distribution of combustible mixture immediately downstream of a flame holder should be mechanically controlled if a preferred mixture composition is to be maintained in that zone. A sloping-baffle combustor configuration gave combustion efficiencies of 90 percent or greater over a range of fuel-air ratios from 0.010 to 0.045.

"The effects of propeller operation on the static longitudinal stability of single-engine tractor monoplanes are analyzed, and a simple method is presented for computing power-on pitching-moment curves for flap-retracted flight conditions. The methods evolved are based on the results of powered-model wind-tunnel investigations of 28 model configurations. Correlation curves are presented from which the effects of power on the downwash over the tail and the stabilizer effectiveness can be rapidly predicted" (p. 399).

From Summary: "Tests were made to fill partly the need for information on the effect of afterbody dimensions on the hydrodynamic stability of a flying boat in smooth water. The dimensions investigated were depth of step, angle of afterbody keel, and length of afterbody. An analysis of the data showed that as either the afterbody length or keel angle was increased an accompanying increase in depth of step was required in order to maintain adequate landing stability."

Report presenting an investigation of the drag on four full-scale models of 16-inch-diameter ramjet engines. The total, base, internal, and external drag were evaluated for each of the models. Results regarding the drag evaluations and drag comparison are provided.

"An iteration method is employed to obtain the flow of a compressible fluid past a curved surface. The first approximation which leads to the Prandtl-Glauert rule, is based on the assumption that the flow differs but little from a pure translation. The iteration process then consists in improving this first approximation in order that it will apply to a flow differing from pure translatory motion to a greater degree. The method fails when the Mach number of the undisturbed stream reaches unity but permits a transition from subsonic to supersonic conditions without the appearance of a compression shock" (p. 305).

A detailed method for determining the jet-boundary corrections for reflection-plane models in rectangular wind tunnels is presented. The method includes the determination of the tunnel span local distribution and the derivation of equations for the corrections to the angle of attack, the lift and drag coefficients, and the pitching-, rolling-, yawing-, and hinge-moment coefficients. The principle effects of aerodynamic induction and of the boundary-induced curvature of the streamlines have been considered. An example is included to illustrate the method. Numerical values of the more important corrections for reflection-plane models in 7 by 10-foot closed wind tunnels are presented.

From Summary: "An analysis has been made of a considerable amount of data for turbulent boundary layers along wings and bodies of various shapes in order to determine the fundamental variables that control the development of turbulent boundary layers. It was found that the type of velocity distribution in the boundary layer could be expressed in terms of a single parameter. This parameter was chosen as the ratio of the displacement thickness to the momentum thickness of the boundary layer. The variables that control the development of the turbulent boundary layer apparently are: (1) the ratio of the nondimensional pressure gradient, expressed in terms of the local dynamic pressure outside the boundary layer and boundary-layer thickness, to the local skin-friction coefficient and (2) the shape of the boundary layer. An empirical equation has been developed in terms of these variables that, when used with the momentum equation and the skin-friction relation, makes it possible to trace the development of the turbulent boundary layer to the separation point."

Report presenting an improvement of the computing procedure of NACA RM A53H17 using a new procedure of harmonic analysis using Tchebichef polynominals. The two main improvements are the simplification of computing procedures and the provision for a comprehensive check solution which includes a direct check of how well the number of harmonics used represent the area-distribution curve.