National Advisory Committee for Aeronautics (NACA) - 746 Matching Results

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Investigations of Tumbling Characteristics of a 1/20-Scale Model of the Northrop N-9M Airplane
From Summary: "The tumbling characteristics of a 1/20-scale model of the Northrop N-9M airplane have been determined in the Langley 20-foot free-spinning tunnel for various configurations and loading conditions of the model. The investigation included tests to determine whether recovery from a tumble could be effected by the use of parachutes. An estimation of the forces due to acceleration acting on the pilot during a tumble was made. The tests were performed at an equivalent test altitude of 15,000 feet."
Investigation of Rim Cracking in Turbine Wheels with Welded Blades
Rim cracking in turbine wheels with welded blades was evaluated. The problem is explained on the basis of the occurrence of plastic flow in the rim during transient starting conditions when thermal compressive stresses resulting from high-temperature gradients exceed the proportional elastic limit of the material.
Landing Characteristics in Waves of Three Dynamic Models of Flying Boats
Powered models of three different flying boats were landed in oncoming wave of various heights and lengths. The resulting motions and acceleration were recorded to survey the effects of varying the trim at landing, the deceleration after landing, and the size of the waves. One of the models had an unusually long afterbody. The data for landing with normal rates of deceleration indicated that the most severe motions and accelerations were likely to occur at some period of the landing run subsequent to the initial impact.
Wind-Tunnel Tests at Low Speed of Swept and Yawed Wings Having Various Plan Forms
Wind tunnel tests haved been made at low speed to various small-scale models of swept-back, swept-forward, and yawed wings. Tests covered changes in aspect ratio, taper ratio, and tip shape.
Flight Tests of Rocket-Powered "Tin-Can" Models of AAF Project MX-800
Flight tests were made of six noninstrumented rocket-powered "Tin Can" models of AAF Project MX-800. Velocity and drag data were obtained by use of CU Doppler radar. The existence of stability and adequate structural strength for flight near zero lift was checked by visual and photographic observation. Drag data obtained during the tests agreed reasonably well with estimates based on experimental data from NACA RM-2 rocket-powered drag research models.
Stick-Fixed Stability and Control Characteristics of the Consolidated Vultee Model 240 Airplane as Estimated from Tests of a 0.092-Scale Powered Model
From Summary: "Estimates of the static stick-fixed stability and control characteristics of the Consolidated Vultee model 240 airplane are presented in this report. The estimates are based on tests of a 0.092-scale powered model in the 10-foot wind tunnel of the Guggenheim Aeronautical Laboratory of the California Institute of Technology. Results of the analysis are evaluated in terms of the Army specifications for stability and control characteristics which are more specific and, in general, equal to or more rigid than the Civil Aeronautics Administration requirements."
Flight Comparison of Performance and Cooling Characteristics of Exhaust-Ejector Installation with Exhaust-Collector-Ring Installation
Flight and ground investigations have been made to compare an exhaust-ejector installation with a standard exhaust-collector-ring installation on air-cooled aircraft engines in a twin-engine airplane. The ground investigation allowed that, whereas the standard engine would have overheated above 600 horsepower, the engine with exhaust ejectors cooled at take-off operating conditions at zero ram. The exhaust ejectors provided as much cooling with cowl flaps closed as the conventional cowl flaps induced when full open at low airspeeds. The propulsive thrust of the exhaust-ejector installation was calculated to be slightly less than the thrust of the collector-ring-installation.
Cooling of Gas Turbines, 2, Effectiveness of Rim Cooling of Blades
An analysis is presented of rim cooling of gas-turbine blades; that is, reducing the temperature at the base of the blade (wheel rim), which cools the blade by conduction alone. Formulas for temperature and stress distributions along the blade are derived and, by the use of experimental stress-rupture data for a typical blade alloy, a relation is established between blade life (time for rupture), operating speed, and amount of rim cooling for several gas temperatures. The effect of blade parameter combining the effects of blade dimensions, blade thermal conductivity, and heat-transfer coefficient is determined. The effect of radiation on the results is approximated. The gas temperatures ranged from 1300F to 1900F and the rim temperature, from 0F to 1000F below the gas temperature. This report is concerned only with blades of uniform cross section, but the conclusions drawn are generally applicable to most modern turbine blades. For a typical rim-cooled blade, gas temperature increases are limited to about 200F for 500F of cooling of the blade base below gas temperature, and additional cooling brings progressively smaller increases. In order to obtain large increases in thermal conductivity or very large decreases in heat-transfer coefficient or blade length or necessary. The increases in gas temperature allowable with rim cooling are particularly small for turbines of large dimensions and high specific mass flows. For a given effective gas temperature, substantial increases in blade life, however, are possible with relatively small amounts of rim cooling.
Correlation of the Trim Limits of Stability Obtained for a PB2Y-3 Flying Boat and a 1/8-Size Powered Dynamic Model
Tests of a PB2Y-3 flying boat were made at the U.S. Naval Air Station, Patuxent River, Md., to determine its hydrodynamic trim limits of stability. Corresponding tests were also made of a 1/8-size powered dynamic model of the same flying boat in Langley tank no. 1. During the tank tests, the full-size testing procedure was reproduced as closely as possible in order to obtain data for a direct correlation of the results. As a nominal gross load of 66,000 pounds, the lower trim limits of the full-size and model were in good agreement above a speed of 80 feet per second. As the speed decreased below 80 feet per second, the difference between the model trim limits and full-scale trim limits gradually became larger. The upper trim limit of the model with flaps deflected 0 deg was higher than that of the full-size, but the difference was small over the speed range compared. At flap deflections greater than 0 deg, it was not possible to trim either the model of the airplane to the upper limit with the center of gravity at 28 percent of the mean aerodynamic chord. The decrease in the lower trim limits with increase in flap deflection showed good agreement for the airplane and model. The lower trim limits obtained at different gross loads for the full-size airplane were reduced to approximately a single curve by plotting trim against the square root of C(sub delta (sub o)) divided by C(sub V).
Wind-Tunnel Tests of the 1/25-Scale Powered Model of the Martin JRM-1 Airplane. 4 - Tests with Ground Board and with Modified Wing and Hull - TED No. NACA 232, Part 4, Tests with Ground Board and with Modified Wing and Hull, TED No. NACA 232
From Summary: "Wind-tunnel tests were made of a 1/25 scale model of the Martin JRM-1 airplane to determine: (1) The longitudinal stability and control characteristics of the JRM-1 model near the water and lateral and directional stability characteristics with power while moving on the surface of the water, the latter being useful for the design of tip floats; (2) The stability and stalling characteristics of the wing with a modified airfoil contour; (3) Stability characteristics of a hull of larger design gross weight; The test results indicated that the elevator was powerful enough to trim the original model in a landing configuration at any lift coefficient within the specified range of centers of gravity."
Wind-tunnel investigation of drooped ailerons on a 16-percent-thick low-drag airfoil
Report presenting a wind-tunnel investigation to determine the practicability of the dropped-aileron-type lateral-control device on NACA low-drag airfoils. Section aerodynamic characteristics of an NACA 66(215)-216 airfoil with an aileron of normal profile and an aileron of straight-sided profile with a modified nose shape are presented for various aileron locations, hinge centers, and aerodynamic balances.
Axial-flow fan and compressor blade design data on 52.5 degrees stagger and further verification of cascade data by rotor tests
From Summary: "Previous tests of blower-blade sections have been extended by a series of tests at 52.5 degrees stagger. The results of these tests have been combined with the earlier test results and are presented in new blade design charts which supersede those previously presented. An investigation in a test blower over a range of stagger from 44 degrees to 65 degrees has shown that for blades at a solidity of 1.0, the two-dimensional cascade data predict the turning angle to within 1/2 degrees."
Preliminary evaluation of the performance of a uniflow two-stroke-cycle spark-ignition engine combined with a blowdown turbine and a steady-flow turbine
Report presenting calculations based on a theoretical analysis for a composite engine consisting of a uniflow two-stroke-cycle spark-ignition engine, a compressor, a blowdown turbine, and a steady-flow turbine. Operation of the engine is considered for four cases of gas mixtures and steady-flow turbine temperatures.
Comparison between flight-measured and calculated span load distribution at high Mach numbers
Report presenting an analysis of the spanwise loading using two different methods on the wing of an airplane for which pressure-distribution measurements were available from flight tests up to a Mach number of 0.866. A comparison between measured and calculated distributions was made on the basis of equal wing-panel normal-force coefficients.
The interdependence of various types of autoignition and knock
A study of the relations existing among pin-point autoignition, homogeneous autoignition, and knock has been made by means of the NACA high-speed camera and the full-view combustion apparatus. High-speed photographic records of combustion, together with corresponding pressure-time traces, of benzene, 2,2,3-trimethylbutane, S-4, and M-4 fuels at various engine conditions have shown the engine conditions under which each of these phenomena occur and the relation of these phenomena to one another.
The interaction of boundary layer and compression shock and its effect upon airfoil pressure distributions
Report presenting an investigation of the mechanism of interaction of compression shock with boundary layer. Shockless pressure distributions at supercritical Mach numbers were found to be accounted for by a marked thickening of the boundary layer for some distance ahead of a shock wave.
An investigation of the aerodynamic characteristics of a rotating axial-flow blade grid
Report presenting the results of an experimental investigation of the aerodynamic characteristics of a rotating axial-flow blade grid with pressure-increasing effect. Several techniques of measurement were used, including pressure distribution measurements, pitot tubes, and hot wire wake surveys. Results regarding the lift and pressure drag of the blade sections, aerodynamic characteristics of the blade sections, profile drag, and static pressure are provided.
Investigation of Thrust Augmentation of a 1600-Pound Thrust Centrifugal-Flow-Type Turbojet Engine by Injection of Refrigerants at Compressor Inlets
Investigations were conducted to determine effectiveness of refrigerants in increasing thrust of turbojet engines. Mixtures of water an alcohol were injected for a range of total flows up to 2.2 lb/sec. Kerosene was injected into inlets covering a range of injected flows up to approximately 30% of normal engine fuel flow. Injection of 2.0 lb/sec of water alone produced an increase in thrust of 35.8% of rate engine conditions and kerosene produced a negligible increase in thrust. Carbon dioxide increased thrust 23.5 percent.
Investigation of NACA 65(sub 112) A111 (approx.) airfoil with 0.35-chord slotted flap at Reynolds numbers up to 25 million
Report presenting an investigation in the two-dimensional low-turbulence tunnel and low-turbulence pressure tunnel to determine the highest maximum lift configurations of a slotted flap on an NACA 65(sub 112)A111 (approx.) airfoil section. The scale effects on aerodynamic characteristics were determined for a range of Reynolds numbers. Results regarding flap configurations, lift characteristics, pitching-moment characteristics, drag characteristics, and effects of leading-edge roughness are provided.
Measurements of the effects of thickness ratio and aspect ratio on the drag of rectangular-plan-form airfoils at transonic speeds
Report presenting testing conducted on two airfoils from a series of rectangular-plan-form airfoils of aspect ratios 7.6 and 5.1 and with NACA 65-006, 65-009, and 65-012 sections using the free-fall method. Results regarding the time histories, ground-velocity data, airfoil drag measurements, and drag coefficients are provided.
Method of designing vaneless diffusers and experimental investigation of certain undetermined parameters
Report presenting a method of designing vaneless diffusers using data given for simple conical diffusers. A family of diffusers with three different cone angles and the same throat height was designed and experimentally studied. A second set of diffusers with varying throats with the best cone angle was also investigated.
Cooling Characteristics of the V-1650-7 Engine 2 - Effect of Coolant Conditions on Cylinder Temperatures and Heat Rejection at Several Engine Powers
From Summary: "An investigation has been conducted on a V-1650-7 engine to determine the cylinder temperatures and the coolant and oil heat rejections over a range of coolant flows (50 to 200 gal/min) and oil inlet temperatures (160 to 2150 F) for two values of coolant outlet temperature (250 deg and 275 F) at each of four power conditions ranging from approximately 1100 to 2000 brake horsepower. Data were obtained for several values of block-outlet pressure at each of the two coolant outlet temperatures. A mixture of 30 percent by volume of ethylene glycol and 70-percent water was used as the coolant."
Cooling Characteristics of the V-1650-7 Engine, 1, Coolant-Flow Distribution, Cylinder Temperatures, and Heat Rejections at Typical Operating Conditions
From Summary: "An investigation was conducted to determine the coolant-flow distribution, the cylinder temperatures, and the heat rejections of the V-1650-7 engine . The tests were run a t several power levels varying from minimum fuel consumption to war emergency power and at each power level the coolant flows corresponded to the extremes of those likely to be encountered in typical airplane installations, A mixture of 30-percent ethylene glycol and 70-percent water was used as the coolant. The temperature of each cylinder was measured between the exhaust valves, between the intake valves, in the center of the head, on the exhaust-valve guide, at the top of the barrel on the exhaust side, and on each exhaust spark-plug gasket."
Preliminary Results of Altitude-Wind-Tunnel Investigation of X24C-4B Turbojet Engine. 5 - Performance of Modified Engine
From Summary: "An investigation has been conducted in the NACA Cleveland altitude wind tunnel to evaluate the performance characteristics of a modified X24C-4B turbojet engine over a range of simulated altitudes from 5000 to 45,000 feet, simulated flight Mach numbers from 0.25 to 1.07, and engine speeds from 4000 to 12,500 rpm. The engine was modified by the manufacturer to improve the velocity and temperature profiles within the engine. Performance data are graphically presented to show the effect of altitude at a flight Mach number of 0.25 and the effect of flight Mach number at an altitude of 25,000 feet."
Fuel investigation in a tubular-type combustor of a turbojet engine
A series of 11 fuels ranging in volatility and including various types of hydrocarbons were tested in a single tubular combustion chamber of a turbojet engine under inlet-air conditions simulating engine operation at two speeds at an altitude of 40,000 feet. Temperature-rise data at various fuel-air ratios were obtained for each set of air-flow conditions. Results regarding the effect of combustor inlet-air conditions on temperature rise, four different series of tests, and a review of some general considerations are provided.
Performance of an axial-flow compressor rotor designed for a pitch-section lift coefficient of 1.20
Report presenting the performance of a set of axial-flow fan and compressor rotor blades with high design loading in a low-speed test blower. The efficiency curve, efficiency contours, comparison of pitch-section turning angles, and simulated blade roughness are provided.
Performance of axial-flow fan and compressor blades designed for high loadings
Report presenting an investigation to determine the effects of loading on the performance of axial-flow fan and compressor blades in a test blower. Results regarding verification of the two-dimensional design data and effects of blade roughness are provided.
A preliminary correlation of the behavior of water rudders on seaplanes and flying boats
From Summary: "This report presents a rough correlation of the dimensions of water rudders of various actual seaplanes and flying boats as related to their behavior. The correlation should be useful for determining the size of a water rudder which will give adequate control for maneuvering at low speeds."
A suggested method of analyzing for transonic flutter of control surfaces based on available experimental evidence
Report presenting the results of a study of the movement of shocks on a three-dimensional wing with and without aileron flutter occurring. The studies include a number of changes and variations to the wing and control. Results for the standard wing and aileron, spoilers at 50 percent chord, upper and lower surface, faired bumps at the 50-percent-chord and 70-percent-chord positions, variations of thickness ratio along the span, vent holes between upper and lower surface, aileron-contour change, aileron mass overbalance, dampers, wing flutter, buffeting forces on fixed controls, and static characteristics are provided.
Preliminary investigation at low speed of downwash characteristics of small-scale sweptback wings
Report presenting an investigation at low speed of the downwash behind various small-scale sweptback wings. The wing configurations used in the testing ranged from aspect ratios of 2.5 to 4.0, sweepback angles from 32.5 degrees to 40 degrees, and ratios of root chord to tip chord of 0.62 to 2.06. Results regarding the effect of aspect ratio, effect of taper ratio, effect of tail span and position, and effect of high-lift devices are provided.
Observations on the behavior of some noncircular aluminum alloy sections loaded to failure in torsion
Report presenting an investigation of the strength and stiffness characteristics of noncircular aluminum alloy sections loaded to failure in torsion. Results regarding torque-twist and torque-stress curves and stress-distribution diagrams are provided.
Bearing strength of some sand-cast magnesium alloys
Report presenting testing to determine the bearing strength characteristics of some magnesium-alloy sand castings and the relation between those and more commonly determined tensile properties. The primary sand-cast magnesium alloys of interest for aircraft design are AM403, AM260, and AM265. Results of all of the tension, compression, and shear tests are provided in tables.
Full-scale investigation of the aerodynamic characteristics of a typical single-rotor helicopter in forward flight
Report presenting an investigation of the forward-flight performance characteristics of a typical single-rotor helicopter equipped with main and tail rotors. Testing occurred over a range of tip-speed ratios and thrust coefficients. Results regarding the fuselage effects and rotor characteristics are provided.
Hydrodynamic impact loads in smooth water for a prismatic float having an angle of dead rise of 30 degrees
Report presenting an investigation involving a prismatic-float forebody of 30 degrees angle of dead rise subjected to impacts in smooth water as part of a series of impact tests to investigate the effects of angle of dead rise on hydrodynamic loads of floats and hulls. Results indicated that the loads encountered during impacts can be predicted within the limits of experimental accuracy by curves and equations.
Drag characteristics of rectangular and swept-back NACA 65-009 airfoils having various aspect ratios as determined by flight tests at supersonic speeds
Report presenting tests to determine the effect of sweepback angle and aspect ratio on the drag at supersonic speeds of wings of NACA 65-009 airfoil section. The current report is part of a bigger investigation and includes results for aspect ratios of 3.8 and 5.0. Results regarding the drag coefficient and general effect of aspect ratio are provided.
Buffeting of External Fuel Tanks at High Speeds on a Grumman F7F-3 Airplane
Attempts were made to alleviate the buffeting of external fuel tanks mounted under the wings of a twin-engine Navy fighter plane. The Mach number at which the buffeting began was increased from 0.529 to 0.640 by streamlining the sway braces and increasing the lateral rigidity of the sway brace system. Further increases of the Mach number, at which buffeting began to 0.725, was obtained by moving the external fuel tank to a position under the fuselage.
Partial Measurements in Flight of the Flying Qualities of a Grumman XF7F-1 Airplane with a Modified Vertical Tail
Partial measurements in flight of the handling qualities of a Grumman XF7F-1 airplane were investigated. Results are for low altitude and normal center of gravity conditions only.
Buffeting of External Fuel Tanks at High Speeds on a Gruman F7F-3 Airplane
Attempts were made to alleviate the buffeting of external fuel tanks mounted under the wings of a twin-engine Navy fighter airplane. The Mach number at which buffeting began was increased from 0,529 to 0.640 by streamlining the sway braces and by increasing the lateral rigidity of the sway brace system. Further increase of the Mach number, at which buffeting began to 0.725, was obtained by moving the external fuel tank to a position under the fuselage.
Altitude-Wind-Tunnel Investigation of the 19B-2, 19B-8, and 19XB-1 Jet Propulsion Engines, 4 - Performance and Windmilling Drag Characteristics
The performance characteristics of the 19B-8 and 19XB-1 turbojet engines and the windmilling-drag characteristics of the 19B-6 engine were determined in the Cleveland altitude wind tunnel. The investigations were conducted on the 19B-8 engine at simulated altitudes from 5000 to 25,000 feet with various free-stream ram-pressure ratios and on the 19XB--1 engine at simulated altitudes from 5000 to 30,000 feet with approximately static free-stream conditions.
Acceleration Characteristics of R-3350 Engine Equipped with NACA Injection Impeller
From Summary: "Qualitative investigations have shown that use of the NACA injection impeller with the R-3350 engine increases the inertia of the fuel-injection system and, when the standard fuel-metering system is used, this increase in inertia results in poor engine acceleration characteristics. This investigation was therefore undertaken to determine whether satisfactory acceleration characteristics of the engine equipped with the injection impeller could be obtained by simple modifications to the fuel-monitoring system. The engine was operated with two types of carburetor; namely, a hydraulic-metering carburetor incorporating a vacuum-operated accelerating pump and a direct-metering carburetor having a throttle-actuated accelerating pump."
Determination of elastic stresses in gas-turbine disks
A method is presented for the calculation of elastic stresses in symmetrical disks typical of those of a high-temperature gas turbine. The method is essentially a finite-difference solution of the equilibrium and compatibility equations for elastic stresses in a symmetrical disk. Account can be taken of point-to-point variations in disk thickness, in temperature, in elastic modulus, in coefficient of thermal expansion, in material density, and in Poisson's ratio. No numerical integration or trial-and-error procedures are involved and the computations can be performed in rapid and routine fashion by nontechnical computers with little engineering supervision. Checks on problems for which exact mathematical solutions are known indicate that the method yields results of high accuracy. Illustrative examples are presented to show the manner of treating solid disks, disks with central holes, and disks constructed either of a single material or two or more welded materials. The effect of shrink fitting is taken into account by a very simple device.
Effect of Mach number on the maximum lift and buffeting boundary determined in flight on a north american P-51D airplane
Flight tests were conducted on a North American P-51D airplane to establish the maximum lift coefficient and the buffeting boundary line as a function of Mach number.
Effect of changing manifold pressure, exhaust pressure, and valve timing on the air capacity and output of a four-stroke engine operated with inlet valves of various diameters and lifts
Report presenting a series of tests made with a CFR engine to determine the effect of inlet-valve capacity, inlet and exhaust pressure, and valve timing on the volumetric efficiency at various speeds. Three combinations of inlet and exhaust pressures and seven valve-timing arrangements were used.
Effect of fuel on performance of a single combustor of an I-16 turbojet engine at simulated altitude conditions
As part of a study of the effects of fuel composition on the combustor performance of a turbojet engine, an investigation was made in a single I-16 combustor with the standard I-16 injection nozzle, supplied by the engine manufacturer, at simulated altitude conditions. The 10 fuels investigated included hydrocarbons of the paraffin olefin, naphthene, and aromatic classes having a boiling range from 113 degrees to 655 degrees F. They were hot-acid octane, diisobutylene, methylcyclohexane, benzene, xylene, 62-octane gasoline, kerosene, solvent 2, and Diesel fuel oil. The fuels were tested at combustor conditions simulating I-16 turbojet operation at an altitude of 45,000 feet and at a rotor speed of 12,200 rpm. At these conditions the combustor-inlet air temperature, static pressure, and velocity were 60 degrees F., 12.3 inches of mercury absolute, and 112 feet per second respectively, and were held approximately constant for the investigation. The reproducibility of the data is shown by check runs taken each day during the investigation. The combustion in the exhaust elbow was visually observed for each fuel investigated.
The effects of yawing thin pointed wings at supersonic speeds
From Summary: "An approximate relation is derived for the surface velocity potential of thin pointed wings at supersonic speeds when they are contained within the Mach cone from the vertex. This relation is applied to obtain the pressure distributions, the lift and drag coefficients, the center of pressure, and the rolling moments as a function of angle of yaw for the delta wing. Theoretical curves are presented for a Mach number of the square root of 2 to illustrate the relations."
Distribution of wave drag and lift in the vicinity of wing tips at supersonic speeds
From Summary: "The point-source-distribution method of calculating the aerodynamic coefficients of thin wings at supersonic speeds was extended to include the effect of the region between the wing boundary and the foremost Mach wave from the wing leading edge. The effect of this region on the surface velocity potential has been determined by an equivalent function, which is evaluated over a portion of the wing surface. In this manner, the effect of angles of attack and yaw as well as the asymmetry of top and bottom wing surfaces may be calculated."
Determination of plate compressive strengths
From Summary: "Results of local-instability tests of H-, Z-, and C-section plate assemblies of four extruded aluminum alloys and two magnesium alloys, obtained in an extensive investigation to determine plate compressive strengths of aircraft structural materials, are summarized. On the basis of the general relationships found between the plate compressive strengths and the compressive stress-strain curves, methods applicable to flat plates and based upon the use of the compressive stress-strain curve are suggested for determining the critical compressive stress and the average stress at maximum load."
The determination of elastic stresses in gas-turbine disks
Report presenting a method for the calculation of elastic stresses in symmetrical disks typical of those of a high-temperature gas turbine. Illustrative examples are presented to demonstrate how to treat solid disks, disks with central holes, and disks constructed of a single material or two or more welded materials.
The use of perforated inlets for efficient supersonic diffusion
Report presenting the use of wall perforations on supersonic diffusers to avoid the internal contraction-ratio limitation. Experimental results on a preliminary model of a perforated diffuser at Mach number 1.85 are provided. A theoretical discussion of the flow coefficients and the size and spacing of the perforations are included.
Design and performance of family of diffusing scrolls with mixed-flow impeller and vaneless diffuser
A family of diffusing scrolls was designed for use with a mixed-flow impeller and a small-diameter vaneless diffuser. The design theory, intended to maintain a uniform pressure around the scroll inlet, permits determination of the position of scroll cross sections of preassigned area by considering the radial variation in fluid density and the effects of friction along the scroll. Inasmuch as the design method leaves the cross-sectional shape undetermined, the effect of certain variations in scroll shape was investigated by studying scrolls having angles of divergence (of the scroll walls downstream of the entrance section) of 24 degrees, 40 degrees, and 80 degrees. A second 80 degree scroll was of asymmetrical construction and a third was plaster-cast instead of sand-cast. Each scroll was tested as a compressor component at actual impeller tip speeds of 700 to 1300 feet per second from full throttle to surge.