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Flight Comparison of Performance and Cooling Characteristics of Exhaust-Ejector Installation with Exhaust-Collector-Ring Installation

Description: 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.
Date: February 14, 1947
Creator: Acker, Loren W. & Kleinknecht, Kenneth S.
Partner: UNT Libraries Government Documents Department

High-Speed Wind-Tunnel Tests of a Model of the Lockheed YP-80A Airplane Including Correlation with Flight Tests and Tests of Dive-Recovery Flaps

Description: This report contains the results of tests of a 1/3-scale model of the Lockheed YP-90A "Shooting Star" airplane and a comparison of drag, maximum lift coefficient, and elevator angle required for level flight as measured in the wind tunnel and in flight. Included in the report are the general aerodynamic characteristics of the model and of two types of dive-recovery flaps, one at several positions along the chord on the lower surface of the wing and the other on the lower surface of the fuselage. The results show good agreement between the flight and wind-tunnel measurements at all Mach numbers. The results indicate that the YP-80A is controllable in pitch by the elevators to a Mach number of at least 0.85. The fuselage dive-recovery flaps are effective for producing a climbing moment and increasing the drag at Mach numbers up to at least 0.8. The wing dive-recovery flaps are most effective for producing a climbing moment at 0.75 Mach number. At 0.85 Mach number, their effectiveness is approximately 50 percent of the maximum. The optimum position for the wing dive-recovery flaps to produce a climbing moment is at approximately 35 percent of the chord.
Date: February 14, 1947
Creator: Cleary, Joseph W. & Gray, Lyle J.
Partner: UNT Libraries Government Documents Department

An Investigation of the Effects of Sweep on the Characteristics of a High-Aspect-Ratio Wing in the Langley 8-Foot High-Speed Tunnel

Description: An untwisted wing, which when unswept has an NACA 65-210 section, an aspect ratio of 9.0 and a taper ration of 2.5:1.0, has been tested with no sweep, and 30 deg and 45 deg of sweepback and sweepforward in conjunction with a typical fuselage at Mach numbers from 0.60 to 0.96 at angles of attack generally between -2 deg and 10 deg in the Langley 8-foot high-speed tunnel. Sweep was obtained by rotating the wing semispans about a point in the plane of symmetry. The normal-force, pitching-moment, profile-drag, and loading characteristics for the wings have been obtained from pressure measurements and wake surveys. The results indicate that the wings with +/-30 deg of sweep experienced the severe changes in characteristics associated with the presence of a shock at higher Mach numbers then did the wing without sweep. The differences between the Mach numbers at which the changes occurred for the wings with +/-30 deg sweep and no sweep were generally slightly less than the factor 1/cosDelta(sub r) times the Mach numbers at which the changes occurred for the unswept wing, Delta(sub r) being the sweep angle. The wings with +/-45 deg of sweep did not experience the changes in the characteristics associated with the presence of shock at an angle of attack of 2 deg at Mach numbers up to the highest test value. The magnitudes of changes in the normal-force and pitching-moment coefficients that occurred were less for the wing with 30 deg of sweep than for the unswept wing. The use of sweepforward was superior to sweepback in delaying and reducing the changes in the normal-force coefficients, but was inferior in delaying and reducing the changes in the profile-drag coefficients. Increasing the Mach number to the highest test values had little effect on the positions of the center ...
Date: February 14, 1947
Creator: Whitcomb, Richard T.
Partner: UNT Libraries Government Documents Department

Aerodynamic Characteristics at High Speeds of Full-Scale Propellers having Different Shank Designs

Description: 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 l0-(5)(08)-03R which had thick cylindrical shank sections typical of conventiona1 blades, The propellers mere tested on a 2000-horsepower dynamometer through a range of blade-angles from 20deg to 55deg at various rotational speeds and at airspeeds up to 496 miles per hour. The resultant tip speeds obtained simulate actual flight conditions, and the variation of air-stream Mach number with advance ratio is within the range of full-scale constant-speed propeller operation. Both propellers were very efficient, the maximum envelope efficiency being approximately 0,95 for the NACA 10-(5)(08)-03 propeller and about 5 percent less for the NACA 10-(5)(08)-03R propeller. Based on constant power and rotational speed, the efficiency of the NACA 10-(05)(08)-03 propeller was from 2.8 to 12 percent higher than that of the NACA 10-(5)(08)-03R propeller over a range of airspeeds from 225 to 450 miles per hour. The loss in maximum efficiency at the design blade angle for the NACA 10-(5)(08)-03 and 10-(5)(08)-03R propellers vas about 22 and 25 percent, respectively, for an increase in helical tip Mach number from 0.70 to 1.14.
Date: February 13, 1947
Creator: Maynard, Julian D.
Partner: UNT Libraries Government Documents Department

Comparison of Wind-Tunnel Predictions with Flight Measurements of the Longitudinal-Stability and -Control Characteristics of a Douglas BTD-1 Airplane

Description: 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. The predicted values were for the most part sufficiently accurate to show the satisfactory and unsatisfactory characteristics in the preliminary design stage and to indicate possible methods of improvement. The discrepancies which did occur were attributed principally to physical dissimilarities between model and airplane and the instability to determine accurately the flight power conditions. The effect of Mach number was considered negligible since the maximum flight test value was about 0.5. In order to simulate more closely the flight conditions and hence obtain more accurate data for predictions, it appears desirable to perform large-scale tests of unorthodox control surfaces such as the sealed vaned elevators with which the airplane was equipped.
Date: February 13, 1947
Creator: Bunnell, Mort V. & Delany, Noel K.
Partner: UNT Libraries Government Documents Department

Investigation of Rim Cracking in Turbine Wheels with Welded Blades

Description: 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.
Date: February 12, 1947
Creator: Millenson, M. B. & Manson, S. S.
Partner: UNT Libraries Government Documents Department

Computed Temperature Distribution and Cooling of Solid Gas-Turbine Blades

Description: Computations were made to determine the temperature distribution and cooling of solid gas-turbine blades.A range of temperatures was used from 1500 degrees to 2500 degrees F, blade-root temperatures from 100 degrees to 1000 degrees F, blade thermal conductivity from 8 to 220 BTU/(hr)(sq ft)(degrees F/ft), and net gas to metal heat transfer coefficients from 75 to 250 BTU/(hr)(sq ft)(degrees F).
Date: February 11, 1947
Creator: Reuter, J. George & Gazley, Carl, Jr.
Partner: UNT Libraries Government Documents Department

Cooling of Gas Turbines, 3, Analysis of Rotor and Blade Temperatures in Liquid-Cooled Gas Turbines

Description: A theoretical analysis of the radial temperature distribution through the rotor and constant cross sectional area blades near the coolant passages of liquid cooled gas turbines was made. The analysis was applied to obtain the rotor and blade temperatures of a specific turbine using a gas flow of 55 pounds per second, a coolant flow of 6.42 pounds per second, and an average coolant temperature of 200 degrees F. The effect of using kerosene, water, and ethylene glycol was determined. The effect of varying blade length and coolant passage lengths with water as the coolant was also determined. The effective gas temperature was varied from 2000 degrees to 5000 degrees F in each investigation.
Date: February 11, 1947
Creator: Brown, W. Byron & Livingood, John N. B.
Partner: UNT Libraries Government Documents Department

Cooling of Gas Turbines I - Effects of Addition of Fins to Blade Tips and Rotor, Admission of Cooling Air Through Part of Nozzles, and Change in Thermal Conductivity of Turbine Components

Description: An analysis was developed for calculating the radial temperature distribution in a gas turbine with only the temperatures of the gas and the cooling air and the surface heat-transfer coefficient known. This analysis was applied to determine the temperatures of a complete wheel of a conventional single-stage impulse exhaust-gas turbine. The temperatures were first calculated for the case of the turbine operating at design conditions of speed, gas flow, etc. and with only the customary cooling arising from exposure of the outer blade flange and one face of the rotor to the air. Calculations were next made for the case of fins applied to the outer blade flange and the rotor. Finally the effects of using part of the nozzles (from 0 to 40 percent) for supplying cooling air and the effects of varying the metal thermal conductivity from 12 to 260 Btu per hour per foot per degree Farenheit on the wheel temperatures were determined. The gas temperatures at the nozzle box used in the calculations ranged from 1600F to 2000F. The results showed that if more than a few hundred degrees of cooling of turbine blades are required other means than indirect cooling with fins on the rotor and outer blade flange would be necessary. The amount of cooling indicated for the type of finning used could produce some improvement in efficiency and a large increase in durability of the wheel. The results also showed that if a large difference is to exist between the effective temperature of the exhaust gas and that of the blade material, as must be the case with present turbine materials and the high exhaust-gas temperatures desired (2000F and above), two alternatives are suggested: (a) If metal with a thermal conductivity comparable with copper is used, then the blade temperature can be reduced ...
Date: February 11, 1947
Creator: Brown, Byron
Partner: UNT Libraries Government Documents Department

Development of Inboard Nacelle for the XB-36 Airplane

Description: A series of investigations of several 1/14-scale models of an inboard nacelle for the XB-36 airplane was made in the Langley two-dimensional low-turbulence tunnels. The purpose of these investigations was to develop a low-drag wing-nacelle pusher combination which incorporated an internal air-flow system. As a result of these investigations, a nacelle was developed which had external drag coefficients considerably lower than the original basic form with the external nacelle drag approximately one-half to two-thirds of those of conventional tractor designs. The largest reductions in drag resulted from sealing the gaps between the wing flaps and nacelle, reducing the thickness of the nacelle training-edge lip, and bringing the under-wing air inlet to the wing leading edge. It was found that without the engine cooling fan adequate cooling air would be available for all conditions of flight except for cruise and climb at 40,000 feet. Sufficient oil cooling at an altitude of 40,000 feet may be obtained by the use of flap-type exit doors.
Date: February 11, 1947
Creator: Nuber, Robert J.
Partner: UNT Libraries Government Documents Department

Theoretical Evaluation of Methods of Cooling the Blades of Gas Turbines

Description: A study was made of heat transfer in turbine blades and the effects on blade temperature of cooling the blade root and tip, changing the dimensions of the blades, raising the cycle temperatures, insulating with ceramics, and cooling by circulation of air or water through hollow blades.
Date: February 11, 1947
Creator: Sanders, J. C. & Mendelson, Alexander
Partner: UNT Libraries Government Documents Department

Analytical comparison of a standard turbojet engine, a turbojet engine with a tail-pipe burner, and a ram-jet engine

Description: From Introduction: "Experimental investigations (reference 1) have shown that in some cases the thrust can be more than doubled by means of tail-pipe burning. A comparison is made of a standard turbojet engine, whose thrust is augmented by tail-pipe burning, and a ram-jet engine. The performance characteristics for the ram-jet engine were computed entirely from theoretical considerations and on the assumption that the burner-inlet velocity was constant."
Date: February 10, 1947
Creator: Krebs, Richard P & Palasics, John
Partner: UNT Libraries Government Documents Department

Two-Dimensional Wind-Tunnel Investigation of Modified NACA 65(sub 112)-111 Airfoil with 35-Percent-Chord Slotted Flap to Determine Pitching-Moment Characteristics and Effects of Roughness

Description: An investigation has been made in the Langley two-dimensional low-turbulence pressure tunnel to develop the optimum configuration of a 0.35-chord slotted flap on an NACA 65(sub 1120)-111 airfoil section modified by removing the trailing-edge cusp. The section pitching-moment characteristics and the effects of standard roughness on the section characteristics were determined for the flap retracted at Reynolds numbers ranging from 3.0 x 10(exp 6) to 9.0 x 10(exp 6).
Date: February 10, 1947
Creator: Racisz, Stanley F.
Partner: UNT Libraries Government Documents Department

Cyclic Engine Test of Cast Vitallium Turbine Buckets - I

Description: An investigation was conducted to correlate the engine service performance of cast Vitallium turbine buckets with standard laboratory metallurgical data. Data were obtained from four I-40 turbine wheels of Timken alloy with cast Vitallium buckets. In order to accelerate bucket deterioration, the turbine wheels were subjected to 20-minute cycles consisting of 5 minutes at idle and 15 minutes at rated speed. A bucket broke on the first wheel during cycle 22 after 7 hours and 20 minutes. The broken bucket was replaced and during the third cycle after the replacement a second bucket broke after a total running time of 8 hours and 12 minutes, The first bucket failure on the second wheel occurred during cycle 29 after 9 hours and 28 minutes; no further failure occurred during 66 additional cycles. Total running time on this wheel was 31 hours and 40 minutes. The third wheel was run for 229 cycles (76 hr and 20 min, total running time) without a. failure. The fourth wheel was operated for 105 cycles (35 hr, total running time) without a failure. Examination of the bro?en buckets indicated that the failures were probably due to fatigue, Massive eutectic areas that existed near the trailing edge probably contributed to the low fatigue strength.
Date: February 7, 1947
Creator: Farmer, Elmo & Darmara, F.N.
Partner: UNT Libraries Government Documents Department

Tank Tests of a 1/7-Size Dynamic Model of the Grumman XJR2F-1 Amphibian to Determine the Effect of Slotted- and Split-Type Flaps on Take-Off Stability - NACA Model 212, TED No. NACA 2378

Description: Additional tests of a 1/7-size model of the Grumman XJR2F-1 amphibian were made in Langley tank no. 1 to compare the behavior during take-off of the model equipped with split- and slotted-type flaps. The slotted flag had a large effect on locating the forward center-of-gravity limits for stable take-offs. Stable take-offs within the normal operating range of positions of the center of gravity could be made with the split flaps deflected 45deg or with the slotted flaps deflected less than 20deg. At flap deflections required for similar take-off stability, the use of split-flaps resulted lower take-off speeds than the use of slotted flaps. An increase in forward acceleration from 1.1 to 4.8 feet per second per second moved the center-of-gravity limit forward approximately 3-percent mean aerodynamic chord.
Date: February 6, 1947
Creator: Land, Norman S. & Zeck, Howard
Partner: UNT Libraries Government Documents Department

High-Speed Load Distribution of the Wing of a 3/16-Scale Model of the Douglas XSB2D-1 Airplane with Flaps Deflected

Description: The tests reported herein were made for the purpose of determining the high-speed load distribution on the wing of a 3/16 scale model of the Douglas XSB2D-1 airplane. Comparisons are made between the root bending moment and section torsional moment coefficients as obtained experimentally and derived analytically. The results show good correlation for the bending moment coefficients but considerable disagreement for the torsional moment coefficients, the measured moments being greater than the analytical moments. The effects of Mach number on both the bending moment and torsional moment coefficients were small.
Date: February 5, 1947
Creator: Barnes, Robert H.
Partner: UNT Libraries Government Documents Department

Performance of the 19XB 10-Stage Axial-Flow Compressor

Description: The 19xB compressor, which replaces the 19B coaapreseor and has the same length and diameter 88 the 19B compressor, was designed with 10 stages to deliver 30 pounds of air per second for a pressure ratio of 4.17 at an equivalent speed of 17,000 rpm; the 19B was designed with six stages for a pressure ratio of 2.7 at the same weight flow and speed as the 19XB compressor. The performance characteristics of the new compressor were determined at the NACA Cleveland laboratory at the request of the Bureau of Aeronautics, Navy Department. Results are presented of the investigation made to evaluate the over-all performance of the compressor, the effects of possible leakage past the rotor rear air seal, the effects of inserting instruments in each row of stator blades and in the first row of outlet guide vanes, and the effects of changing the temperature and the pressure of the inlet air. The results of the interstage surveys are also presented.
Date: February 4, 1947
Creator: Downing, Richard M. & Finger, Harold B.
Partner: UNT Libraries Government Documents Department

Knock-Limited Power Outputs from a CFR Engine Using Internal Coolants, 3, Four Alkyl Amines, Three Alkanolamines, Six Amides, and Eight Heterocyclic Compounds

Description: An investigation of the antiknock effectiveness of various additive-water solutions when used as internal coolants has been conducted at the NACA Cleveland laboratory. Nine compounds have been previously run in a CFR engine and the results are presented. In an effort to find a good anti-knock-coolant additive with more desirable physical properties than those of the nine compounds previously investigated, water solutions of four alkyl amines, three alkanolamines, six amides, and eight heterocyclic compounds were investigated and the results are presented.
Date: February 3, 1947
Creator: Imming, Harry S. & Bellman, Donald R.
Partner: UNT Libraries Government Documents Department

Application of the analogy between water flow with a free surface and two-dimensional compressible gas flow

Description: From Introduction: "The development of the measuring apparatus and techniques is presented herein. The application of the analogy to flows through nozzles and about circular cylinders at subsonic velocities extending into supercritical range is also presented."
Date: February 1947
Creator: Orlin, W James; Lindner, Norman J & Bitterly, Jack G
Partner: UNT Libraries Government Documents Department