Report presenting an investigation of the altitude performance of a 28-inch diameter ram-jet engine using a direct-connect system in an altitude test chamber. The majority of the investigation occurred at Mach number 2 at altitudes above the tropopause (250 degrees Fahrenheit inlet temperature). Various design configurations were explored and runs were made with different types of fuel.

Memorandum presenting a supersonic wind-tunnel investigation of store interference performed in the 4- by 4-foot supersonic pressure tunnel at a Mach number of 2.01 in which separate forces on a store and a swept-wing-fuselage combination were measured. The report presents data on a configuration which simulated a heavy-bomber airplane with a large external store.

Report presenting calculated performance characteristics of a ducted rocket with gasoline and liquid oxygen as the fuel mixture and with a mass flow of 1 slug per second. Evaluations of net thrust, frontal area, thrust per unit frontal area, and specific fuel consumption are given for all of the flight conditions under which it might operate.

Report presenting a blade-vibration survey that was conducted during normal operation of a 10-stage axial-flow compressor powered by part of a complete jet engine. Strain-gage records were obtained from all stages during acceleration, deceleration, and constant-speed runs. Results regarding the inlet disturbances and damping characteristics are provided.

From Introduction: "Tests have recently been conducted in the Langley 8-foot high-speed tunnel (reference 1) to study the effects of changes in operating advance ratio, blade plan form, blade-section thickness, section camber, and other variables on the on the propeller characteristics in the transonic-speed range. The method in reference 2, which evaluated the profile drag losses and the induced losses seperately, is followed in this paper. The method as presented offers the general prediction of propeller performance, and can be used to supplement the experimental data."

Memorandum presenting the results of measurements of gust and draft velocities within thunderstorms at an air field over a 7-day period. The data are summarized in tables and compared to previous flights.

The results of an altitude test-chamber investigation of the effects of a number of design changes and operating conditions on altitude peformance of a 28-inch diameter ram jet engine are presented. Most of the investigation was for a simulated flight Mach number of 2.0 above the tropopause. Fuel-air distribution, gutter width, the presence of a pilot flame, cimbustion-chamber-inlet temperature, and exhaust-nozzle throat area were found to have significant effects on limits of combustion. Combustion efficiency increased with increasing combustion-chamber-inlet temperature and was adversely affected by an increase in the exhaust-nozzld area. Similiar lean limits of combustion were obtained for both Diesel fuel and normal heptane, but combustion efficiences obtained with Diesel fuel were lower than those obtained with normal heptane.

Report presenting an investigation of the time lag between flap deflection and force development on a rectangular wing with a 9-percent-thick symmetrical circular-arc profile with a full-span 30-percent-chord flap. This was performed in order to determine further information about the rapidity of response for a supersonic missile after a given flap deflection due to the potential time lag between the deflection of the controls surfaces and the development of aerodynamic forces.

"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.

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.

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.

From Introduction: "The primary purpose of this paper is to describe progress in the aerodynamics of wings, bodies, and wing-body combinations at high angles of attack."

Report presenting an investigation of store interference in the supersonic pressure tunnel at Mach number 2.01 in which separate forces on a store and a swept-wing-fuselage combination were measured. The interference effects measured at that Mach number were similar to those reported previously at Mach number 1.61. Results regarding store drag, store lift, store side force, store pitching moment and yawing moment, wing-fuselage drag, wing-fuselage lift, total drag, total lift, and wing-fuselage flow field are provided.

Report presenting experimental force and moment data for rectangular wings of aspect ratios 1, 2, and 3 at a range of angles of attack and Mach numbers. Shock-expansion theory was found to adequately predict the span load distribution in the two-dimensional flow region below the shock-detachment angle. Results regarding basic physical data, the attached regime, and the detached regime are provided.

From Summary: "A preliminary experimental study of symmetrical, circular, internal compression inlets has shown that they attain pressure recovery equal to that measured by conical nose inlets at Mach numbers up to about 2.3. This pressure recovery was obtained with configurations having essentially zero pressure drag of the external surfaces."

During a free-jet investigation of a 28-inch ram-jet engine at a Mach number of 2.35, flow pulsation at the engine inlet were discovered which proved to have an effect on the engine performance and operational characteristics, particularly the engine rich blowout limits. This report discusses the finding of the flow pulsations, their elimination, and effect. Other facility characteristics, such as the establishment of flow simulation and the degree of subcritical operation of the diffuser, are also explained.

"Low Mach number longitudinal-stability and control characteristics as predicted by use of wind tunnel data from a powered 3/16-scale model are compared with flight test measurements of a Navy BTD-1 airplane. The accuracy of the wind tunnel data and the discrepancies involved in attempting to correlate with flight data are discussed and analyzed. The comparison showed that wind tunnel predictions were, in general, in good agreement with flight test data" (p. 1).

Report presenting the cloth permeability of rolling a tapering thickness on a 20x200-mesh stainless-steel wire clothing investigated experimentally. The application of the cloth was for the shell of a transpiration-cooled turbine blade operating at gas and shell temperatures of 2500 and 10000 degrees Fahrenheit. Results regarding the taper-rolled cloth and comparison of taper-and flat-rolled samples are provided.

"Tests of two 10-foot-diameter two-blade propellers which differed only in shank design have been made in the Langley 16-foot high-speed tunnel. The propellers are designated by their blade design numbers, NACA 10-(5)(08)-03, which had aerodynamically efficient airfoil shank sections, and NACA 10-(5)(08)-03R which had thick cylindrical shank sections typical of conventional blades. The propellers mere tested on a 2000-horsepower dynamometer through a range of blade-angles from 20 degrees to 55 degrees at various rotational speeds and at airspeeds up to 496 miles per hour" (p. 1).

Report presenting the results of an experimental investigation of several types of aerodynamically balanced trailing-edge flaps on an aspect ratio 2 triangular wing are presented. The balancing devices tested consisted of flap overhang, paddles, rectangular and triangular horns, and trailing-edge tabs. Results regarding the lift, drag, pitching moment, hinge moment, and rolling moment are presented for a range of Mach numbers and a constant Reynolds number.

The gust and draft velocities from records of NACA instruments installed in P-61C airplanes participating in thunderstorm flights at Clinton County Army Air FIeld, Ohio, from August 7, 1947 to August 13, 1947 are presented.

This report contains the results of the investigation of the aerodynamic characteristics of the flying mock-up of the Consolidated Vultee XP-92 airplane as conducted in the Ames 40- by 80-foot wind tunnel, Data are presented for test conditions which would give information as to the limits of stability and controllability, and also, the effect of Reynolds number. No analysis of the data has been made.