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  Partner: UNT Libraries Government Documents Department
 Decade: 1950-1959
 Serial/Series Title: NACA Technical Notes
 Collection: National Advisory Committee for Aeronautics Collection
Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors

Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors

Date: October 1, 1951
Creator: Castles, Walter, Jr. & Gray, Robin B.
Description: The empirical relation between the induced velocity, thrust, and rate of vertical descent of a helicopter rotor was calculated from wind tunnel force tests on four model rotors by the application of blade-element theory to the measured values of the thrust, torque, blade angle, and equivalent free-stream rate of descent. The model tests covered the useful range of C(sub t)/sigma(sub e) (where C(sub t) is the thrust coefficient and sigma(sub e) is the effective solidity) and the range of vertical descent from hovering to descent velocities slightly greater than those for autorotation. The three bladed models, each of which had an effective solidity of 0.05 and NACA 0015 blade airfoil sections, were as follows: (1) constant-chord, untwisted blades of 3-ft radius; (2) untwisted blades of 3-ft radius having a 3/1 taper; (3) constant-chord blades of 3-ft radius having a linear twist of 12 degrees (washout) from axis of rotation to tip; and (4) constant-chord, untwisted blades of 2-ft radius. Because of the incorporation of a correction for blade dynamic twist and the use of a method of measuring the approximate equivalent free-stream velocity, it is believed that the data obtained from this program are more applicable to free-flight calculations than ...
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Droplet Impingement and Ingestion by Supersonic Nose Inlet in Subsonic Tunnel Conditions

Droplet Impingement and Ingestion by Supersonic Nose Inlet in Subsonic Tunnel Conditions

Date: May 1, 1958
Creator: Gelder, Thomas F.
Description: The amount of water in cloud droplet form ingested by a full-scale supersonic nose inlet with conical centerbody was measured in the NACA Lewis icing tunnel. Local and total water impingement rates on the cowl and centerbody surfaces were also obtained. All measurements were made with a dye-tracer technique. The range of operating and meteorological conditions studied was: angles of attack of 0 deg and 4.2 deg, volume-median droplet diameters from about 11 to 20 microns, and ratios of inlet to free-stream velocity from about 0.4 to 1.8. Although the inlet was designed for supersonic (Mach 2.0) operation of the aircraft, the tunnel measurements were confined to a free-stream velocity of 156 knots (Mach 0.237). The data are extendable to other subsonic speeds and droplet sizes by dimensionless impingement parameters. Impingement and ingestion efficiencies are functions of the ratio of inlet to free-stream velocity as well as droplet size. For the model and range of conditions studied, progressively increasing the inlet velocity ratio from less than to greater than 1.0 increased the centerbody impingement efficiency and shifted the cowl impingement region from the inner- to outer-cowl surfaces, respectively. The ratio of water ingested by the inlet plane to that contained ...
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A Dye-Tracer Technique for Experimentally Obtaining Impingement Characteristics of Arbitrary Bodies and a Method for Determining Droplet Size Distribution

A Dye-Tracer Technique for Experimentally Obtaining Impingement Characteristics of Arbitrary Bodies and a Method for Determining Droplet Size Distribution

Date: March 1, 1955
Creator: VonGlahn, Uwe H.; Gelder, Thomas F. & Smyers, William H., Jr.
Description: A dye-tracer technique has been developed whereby the quantity of dyed water collected on a blotter-wrapped body exposed to an air stream containing a dyed-water spray cloud can be colorimetrically determined in order to obtain local collection efficiencies, total collection efficiency, and rearward extent of impingement on the body. In addition, a method has been developed whereby the impingement characteristics obtained experimentally for a body can be related to theoretical impingement data for the same body in order to determine the droplet size distribution of the impinging cloud. Several cylinders, a ribbon, and an aspirating device to measure cloud liquid-water content were used in the studies presented herein for the purpose of evaluating the dye-tracer technique. Although the experimental techniques used in the dye-tracer technique require careful control, the methods presented herein should be applicable for any wind tunnel provided the humidity of the air stream can be maintained near saturation.
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Effect of Ice and Frost Formations on Drag of NACA 65(sub 1) -212 Airfoil for Various Modes of Thermal Ice Protection

Effect of Ice and Frost Formations on Drag of NACA 65(sub 1) -212 Airfoil for Various Modes of Thermal Ice Protection

Date: June 1, 1953
Creator: Gray, V. H. & Von Glahn, U. H.
Description: The effects of primary and. runback icing and frost formations on the drag of an 8-foot-chord NACA 651-212 airfoil section were investigated over a range of angles of attack from 20 to 80 and airspeeds up to 260 miles per hour for icing conditions with liquid-water contents ranging from 0.25 to 1.4 grams per cubic meter and datum air temperatures of -30 to 30 F. The results showed that glaze-ice formations, either primary or runback, on the upper surface near the leading edge of the airfoil caused large and rapid increases in drag, especially at datum air temperatures approaching 32 F and in the presence of high rates of water catch. Ice formations at lower temperatures (rime ice) did not appreciably increase the drag coefficient over the initial (standard roughness) drag coefficient. Cyclic de-icing of the primary Ice formations on the airfoil leading-edge section permitted the drag coefficient to return almost to the bare airfoil drag value. Runback icing on the lower surface did not present a serious drag problem except when heavy spanwise ridges of runback ice occurred aft of the heatable area. Frost formations caused rapid and large increases in drag with incipient stalling of the airfoil.
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Effects of extreme surface cooling on boundary-layer transition

Effects of extreme surface cooling on boundary-layer transition

Date: October 1, 1957
Creator: Jack, J. R.; Wisniewski, R. J. & Diaconis, N. S.
Description: None
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Correlations Among Ice Measurements, Impingement Rates Icing Conditions, and Drag Coefficients for Unswept NACA 65A004 Airfoil

Correlations Among Ice Measurements, Impingement Rates Icing Conditions, and Drag Coefficients for Unswept NACA 65A004 Airfoil

Date: February 1, 1958
Creator: Gray, Vernon H.
Description: An empirical relation has been obtained by which the change in drag coefficient caused by ice formations on an unswept NACA 65AO04 airfoil section can be determined from the following icing and operating conditions: icing time, airspeed, air total temperature, liquid-water content, cloud droplet impingement efficiencies, airfoil chord length, and angles of attack. The correlation was obtained by use of measured ice heights and ice angles. These measurements were obtained from a variety of ice formations, which were carefully photographed, cross-sectioned, and weighed. Ice weights increased at a constant rate with icing time in a rime icing condition and at progressively increasing rates in glaze icing conditions. Initial rates of ice collection agreed reasonably well with values predicted from droplet impingement data. Experimental droplet impingement rates obtained on this airfoil section agreed with previous theoretical calculations for angles of attack of 40 or less. Disagreement at higher angles of attack was attributed to flow separation from the upper surface of the experimental airfoil model.
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Comparison of Heat Transfer from Airfoil in Natural and Simulated Icing Conditions

Comparison of Heat Transfer from Airfoil in Natural and Simulated Icing Conditions

Date: September 1, 1951
Creator: Gelder, Thomas F. & Lewis, James P.
Description: An investigation of the heat transfer from an airfoil in clear air and in simulated icing conditions was conducted in the NACA Lewis 6- by 9-foot icing-research tunnel in order to determine the validity of heat-transfer data as obtained in the tunnel. This investiation was made on the same model NACA 65,2-016 airfoil section used in a previous flight study, under similar heating, icing, and operating conditions. The effect of tunnel turbulence, in clear air and in icingwas indicated by the forward movement of transition from laminar to turbulent heat transfer. An analysis of the flight results showed the convective heat transfer in icing to be considerably different from that measured in clear air and. only slightly different from that obtained in the icing-research tunnel during simulated icing.
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Analogy Between Mass and Heat Transfer with Turbulent Flow

Analogy Between Mass and Heat Transfer with Turbulent Flow

Date: October 1, 1953
Creator: Callaghan, Edmund E.
Description: An analysis of combined heat and mass transfer from a flat plate has been made in terms of Prandtl t s simplified physical concept of the turbulent boundary layer. The results of the analysis show that for conditions of reasonably small heat and mass transfer, the ratio of the mass-and heat-transfer coefficients is dependent on the Reynolds number of the boundary layer, the Prandtl number of the medium of diffusion, and the Schmidt number of the diffusing fluid in the medium of diffusion. For the particular case of water evaporating into air, the ratio of mass-transfer coefficient to heat-transfer coefficient is found to be slightly greater than unity.
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Analytical Investigation of Icing Limit for Diamond-Shaped Airfoil in Transonic and Supersonic Flow

Analytical Investigation of Icing Limit for Diamond-Shaped Airfoil in Transonic and Supersonic Flow

Date: January 1, 1953
Creator: Callaghan, Edmund E. & Serafini, John S.
Description: Calculations have been made for the icing limit of a diamond airfoil at zero angle of attack in terms of the stream Mach number, stream temperature, and pressure altitude. The icing limit is defined as a wetted-surface temperature of 320 F and is related to the stream conditions by the method of Hardy. The results show that the point most likely to ice on the airfoil lies immediately behind the shoulder and is subject to possible icing at Mach numbers as high as 1.4.
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Experimental investigation of an NACA 64A010 airfoil section with 41 suction slots on each surface for control of laminar boundary layer

Experimental investigation of an NACA 64A010 airfoil section with 41 suction slots on each surface for control of laminar boundary layer

Date: April 1, 1952
Creator: Burrows, D. L. & Schwartzberg, M. A.
Description: None
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A thermal system for continuous monitoring of laminar and turbulent boundary-layer flows during routine flight

A thermal system for continuous monitoring of laminar and turbulent boundary-layer flows during routine flight

Date: September 1, 1957
Creator: Richardson, N. R. & Horton, E. A.
Description: None
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Simplified method for determination of critical height of distributed roughness particles for boundary-layer transition at Mach numbers from 0 to 5

Simplified method for determination of critical height of distributed roughness particles for boundary-layer transition at Mach numbers from 0 to 5

Date: September 1, 1958
Creator: Braslow, A. L. & Knox, E. C.
Description: None
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Further experimental studies of area suction for the control of the laminar boundary layer on a porous bronze NACA 64A010 airfoil

Further experimental studies of area suction for the control of the laminar boundary layer on a porous bronze NACA 64A010 airfoil

Date: May 1, 1950
Creator: Braslow, A. L. & Viscounti, F.
Description: None
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A flight investigation of the practical problems associated with porous-leading-edge suction

A flight investigation of the practical problems associated with porous-leading-edge suction

Date: February 11, 1954
Creator: Hunter, P. A. & Johnson, H. I.
Description: None
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The Interference Effects of a Body on the Spanwise Load Distributions of Two 45 Degree Sweptback Wings of Aspect Ratio 8.02 from Low-Speed Tests

The Interference Effects of a Body on the Spanwise Load Distributions of Two 45 Degree Sweptback Wings of Aspect Ratio 8.02 from Low-Speed Tests

Date: April 1, 1956
Creator: Martina, Albert P.
Description: Tests of two wing-body combinations have been conducted in the Langley 19-foot pressure tunnel at a Reynolds number of 4 x 10(exp 6) and a Mach number of 0.19 to determine the effects of the bodies on the wing span load distributions. The wings had 45 degrees sweepback of the quarter-chord line, aspect ratio 8.02, taper ratio 0.45, and incorporated 12-percent-thick airfoil sections streamwise. One wing was untwisted and uncambered whereas the second wing incorporated both twist and camber. Identical bodies of revolution, of 10:1 fineness ratio, having diameter-to-span ratios of 0.10, were mounted in mid-high-wing arrangements. The effects of wind incidence, wing fences, and flap deflection were determined for the plane uncambered wing. The addition of the body to the plane wing increased the exposed wing loading at a given lift coefficient as much as 10 percent with the body at 0 degrees incidence and 4 percent at 4 degrees incidence. The bending-moment coefficients at the wing-body juncture were increased about 2 percent with the body at 0 degrees incidence, whereas the increases were as much as 10 percent with the body at 4 degrees incidence. The spanwise load distributions due to the body on the plane wing as ...
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On the permeability of porous materials

On the permeability of porous materials

Date: January 1, 1956
Creator: Yates, E. C., Jr.
Description: None
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A theoretical study of the effect of forward speed on the free-space sound-pressure field around propellers

A theoretical study of the effect of forward speed on the free-space sound-pressure field around propellers

Date: January 1, 1954
Creator: Garrick, I. E. & Watkins, C. E.
Description: None
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Experimental study of the effects of finite surface disturbances and angle of attack on the laminar boundary layer of an NACA 64A010 airfoil with area suction

Experimental study of the effects of finite surface disturbances and angle of attack on the laminar boundary layer of an NACA 64A010 airfoil with area suction

Date: October 1, 1952
Creator: Schwartzberg, M. A. & Braslow, A. L.
Description: None
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Determination of Shapes of Boattail Bodies of Revolution for Minimum Wave Drag

Determination of Shapes of Boattail Bodies of Revolution for Minimum Wave Drag

Date: November 1, 1951
Creator: Adams, Mac C.
Description: 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. According to linearized theory, the optimum profiles are found to have infinite slope at the nose but zero radius of curvature so that the bodies appear to have pointed noses, a zero slope at the body base, and no variation of wave drag with Mach number. For those bodies having a specified intermediate.diameter (that is, location and magnitude given), the maximum body diameter is shown to be larger, in general, than the specified diameter. It is also shown that, for bodies having a specified maximum diameter, ...
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Meteorological Analysis of Icing Conditions Encountered in Low-Altitude Stratiform Clouds

Meteorological Analysis of Icing Conditions Encountered in Low-Altitude Stratiform Clouds

Date: March 1, 1951
Creator: Kline, D. B. & Walker, J. A.
Description: Liquid-water content, droplet size, and temperature data measured during 22 flights in predominatly stratiform clouds through the 1948-49 and the 1949-50 winters are presented. Several icing encounters were of greater severity than those previously measured over the same geographical area, but were within the limits of similar measurements obtained over different terrain within the United States. An analysis of meteorological conditions existing during the 74 flights conducted for four winters indicated an inverse relation of liquid-water concentration to maximum horizontal extent of icing clouds. Data on the vertical extent of supercooled clouds are also presented. Icing conditions were most likely to occur in the southwest and northwest quadrants of a cyclone area, and least likely to occur in the southeast and northeast quadrants where convergent air flow and lifting over the associated warm frontal surface usually cause precipitation. Additional data indicated that, icing conditions were usually encountered in nonprecipitating clouds existing at subfreezing temperatures and were unlikely over areas where most weather observing stations reported the existence of precipitation. Measurements of liquid-water content obtained during 12 flights near the time and location of radiosonde observations were compared with theoretical values. The average liquid-water content of a cloud layer, as measured ...
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Photomicrographic Investigation of Spontaneous Freezing Temperatures of Supercooled Water Droplets

Photomicrographic Investigation of Spontaneous Freezing Temperatures of Supercooled Water Droplets

Date: July 1, 1950
Creator: Dorsch, R. G. & Hacker, P. T.
Description: A photomicrographic technique for investigating eupercooled. water droplets has been devised and. used. to determine the spontaneous freezing temperatures of eupercooled. water droplets of the size ordinarily found. in the atmosphere. The freezing temperatures of 4527 droplets ranging from 8.75 to 1000 microns in diameter supported on a platinum surface and 571 droplets supported on copper were obtained. The average spontaneous freezing temperature decreased with decrease in the size of the droplets. The effect of size on the spontaneous freezing temperature was particularly marked below 60 microns. Frequency-distribution curves of the spontaneous freezing temperatures observed for droplets of a given size were obtained. Although no droplet froze at a temperature above 20 0 F, all droplets melted at 32 F. Results obtained with a copper support did not differ essentially from those obtained with a platinum surface.
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Penetration of Air Jets Issuing from Circular, Square, and Elliptical Orifices Directed Perpendicularly to an Air Stream

Penetration of Air Jets Issuing from Circular, Square, and Elliptical Orifices Directed Perpendicularly to an Air Stream

Date: February 1, 1950
Creator: Ruggeri, Robert S.; Callaghan, Edmund E. & Bowden, Dean T.
Description: An experimental investigation was conducted to determine the penetration of air jets d.irected perpendicularlY to an air stream. Jets Issuing from circular, square, and. elliptical orifices were investigated. and. the jet penetration at a position downstream of the orifice was determined- as a function of jet density, jet velocity, air-stream d.enaity, air-stream velocity, effective jet diameter, and. orifice flow coeffIcient. The jet penetrations were determined for nearly constant values of air-stream density at three tunnel-air velocities arid for a large range of Jet velocities and. densities. The results were correlated in terms of dimensionless parameters and the penetrations of the various shapes were compared. Greater penetration was obtained. with the square orifices and the elliptical orifices having an axis ratio of 4:1 at low tunnel-air velocities and low jet pressures than for the other orifices investigated. The square orifices gave the best penetrations at the higher values of tunnel-air velocity and jet total pressure.
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An Oil-Stream Photomicrographic Aeroscope for Obtaining Cloud Liquid-Water Content and Droplet Size Distributions in Flight

An Oil-Stream Photomicrographic Aeroscope for Obtaining Cloud Liquid-Water Content and Droplet Size Distributions in Flight

Date: January 1, 1956
Creator: Hacker, Paul T.
Description: An airborne cloud aeroscope by which droplet size, size distribution, and liquid-water content of clouds can be determined has been developed and tested in flight and in wind tunnels with water sprays. In this aeroscope the cloud droplets are continuously captured in a stream of oil, which Is then photographed by a photomicrographic camera. The droplet size and size distribution can be determined directly from the photographs. With the droplet size distribution known, the liquid-water content of the cloud can be computed from the geometry of the aeroscope, the airspeed, and the oil-flow rate. The aeroscope has the following features: Data are obtained semi-automatically, and permanent data are taken in the form of photographs. A single picture usually contains a sufficient number of droplets to establish the droplet size distribution. Cloud droplets are continuously captured in the stream of oil, but pictures are taken at Intervals. The aeroscope can be operated in icing and non-icing conditions. Because of mixing of oil in the instrument, the droplet-distribution patterns and liquid-water content values from a single picture are exponentially weighted average values over a path length of about 3/4 mile at 150 miles per hour. The liquid-water contents, volume-median diameters, and distribution ...
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Simple graphical solution of heat transfer and evaporation from surface heated to prevent icing

Simple graphical solution of heat transfer and evaporation from surface heated to prevent icing

Date: October 1, 1952
Creator: Gray, V. H.
Description: None
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