National Advisory Committee for Aeronautics (NACA) - 37 Matching Results

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Calculations of the Supersonic Wave Drag of Nonlifting Wings with Arbitrary Sweepback and Aspect Ratio: Wings Swept Behind the Mach Lines

Description: On the basis of a recently developed theory for finite sweptback wings at supersonic speeds, calculations of the supersonic wave drag at zero lift were made for a series of wings having thin symmetrical biconvex sections with untapered plan forms and various angles of sweepback and aspect ratios. The results are presented in a unified form so that a single chart permits the direct determination of the wave drag for this family of airfoils for an extensive range of aspect ratio and sweepback angle for stream Mach numbers up to a value corresponding to that at which the Mach line coincides with the wing leading edge. The calculations showed that in general the wave-drag coefficient decreased with increasing sweepback. At Mach numbers for which the Mach lines are appreciably ahead of the wing leading edge, the 'wave-drag coefficient decreased to an important extent with increases in aspect ratio or slenderness ratio. At Mach numbers for which the Mach lines approach the wing leading edge (Mach numbers approaching a value equal to the secant of the angle of sweepback), the wave-drag coefficient decreased with reductions in aspect ratio or slenderness ratio. In order to check the results obtained by the theory, a comparison was made with the results of tests at the Langley Memorial Aeronautical Laboratory of sweptback wing attached to a freely falling body. The variation of the drag with Mach number and aspect ratio as given by the theory appeared to be in reasonable.
Date: February 21, 1947
Creator: Harmon, Sidney M & Swanson, Margaret D
Partner: UNT Libraries Government Documents Department

Aerodynamic characteristics of a wing with unswept quarter-chord line, aspect ratio 4, taper ratio 0.6, and NACA 65A006 airfoil section

Description: From Introduction: "This paper presents the results of the investigation of the wing-alone and of the wing-fuselage configuration employing a wing with an unswept quarter-chord line, aspect ratio 4, taper ratio 0.6, and an NACA 65A006 airfoil section parallel to the air stream. The results of closely related sweptback-wing investigations, which are part of the present transonic programs, are presented in references 1 to 3."
Date: October 21, 1949
Creator: Goodson, Kenneth W & Morrison, William D , Jr
Partner: UNT Libraries Government Documents Department

Aerodynamic characteristics of a wing with quarter-chord line swept back 35 degrees, aspect ratio 4, taper ratio 0.6, and NACA 65A006 airfoil section : transonic-bumb method

Description: From Introduction: "This paper presents the results of the investigation of wing-alone and wing-fuselage combinations employing a wing with the quarter-chord line swept back 35^o, aspect ratio 4, taper ratio 0.6, and NACA 65A006 airfoil section."
Date: April 21, 1949
Creator: Sleeman, William C , Jr & Becht, Robert E
Partner: UNT Libraries Government Documents Department

Performance of the 19XB 10-Stage Axial-Flow Compressor with Altered Blade Angles

Description: Previous performance data of the 19XB axial-flow compressor indicated that the outlet guide vanes and possibly the inlet guide vanes were stalling. Calculations were made to determine if these adverse conditions could be eliminated and if the manufacturer's design specifications could be more nearly approached by altering the blade angles of the first few compression stages as well as the outlet guide vanes. With the blade angles altered, experimental data were taken at compressor speeds of 8500 to 17,000 rpm with inlet-air conditions of 7.4 inches of mercury absolute and 59 0 F. The temperature-rise efficiency increased with speed from 0.70 at 8500 rpm to 0.74 at 13,600 rpm and dropped gradually to 0.70 at 17,000 rpm. At the design speed of 17,000 rpm, the pressure ratio at the peak efficiency point was 3.63. The maximum pressure ratio at design speed was 4.15 at an equivalent weight flow of 29.8 pounds per second. The altered compressor operated very .near the design specifications of pressure ratio and equivalent weight flow. At the high speeds, the peak adiabatic temperature-rise efficiency was increased 0.02 to 0,06 by altering the blade angles. The peak pressure ratio was increased 0.29 at design speed (17,000 rpm) and 0.05 and 0.13 at 11,900 and 13,600 rpm, respectively. The equivalent weight flow through the altered compressor was reduced 2 pounds per second at 15,300 and 17,000 rpm, as was expected from the design calculations. As extreme caution was taken not to surge the compressor violently, the point of minimum air flow may not have been reached in the present investigation and in a previous investigation. A true comparison of the pressure ratios obtained at the high speeds therefore cannot be made.
Date: January 21, 1947
Creator: Downing, Richard M.; Finger, Harold B. & Roepcke, Fay A.
Partner: UNT Libraries Government Documents Department

Investigation of High-Performance Fuels in Multicylinder and in Single-Cylinder Engines at High and Cruising Engine Speeds

Description: An investigation was conducted to compare the knock-limited performance of a 20-percent triptane blend in 28-K fuel with that of 28-R and 33-R fuels at high engine speeds, cruising speeds, and two compression ratios in an K-1830-94 multicylinder engine, Data were obtained with the standard compression ratio of 6.7 and with a compression ratio of 3.0, The three fuels were investigated at engine speeds of 1800, 2250, 2600, and 2800 rpm at high and low blower ratios. A carburetor-air temperature of approximate1y 100 deg F was maintained for the multicylinder-engine runs, Data were obtained on a single R-1830-94 cylinder engine as a means of checking the multicylinder data at the higher speeds. A satisfactory correlation between average mixture temperature and knock-limited manifold pressure was obtained by plotting knock-limited manifold pressure against average mixture temperature for the whole range of engine speeds at constant carburetor air temperature and cylinder-head temperature. The single-cylinder knock-limited performance based on charge-air flow matched that of the multicylinder engine within 6 percent under all the conditions except for 28-R fuel at 2800 rpm; these curves differed from each other by 11 percent in the rich region. The knock rating of 33-R fuel was found to be a little higher than that of the 20-percent triptane blend and 26-R fuel at high mixture temperatures (above 210 deg F) and lean mixtures. The 33-R fuel exhibited rich knock limits appreciably lower than the 20-percent triptane blend, Increasing the compression ratio from 6.7 to 8.0 lowered the knock-limited manifold pressure for all fuels approximately 15 to 18 inches of mercury absolute in the cruising range and 20 to 28 inches of mercury absolute at higher engine speeds. Brake specific fuel consumption was reduced 7 to 9 percent by the increase in compression ratio from 6.7 to 8,0,.
Date: February 21, 1947
Creator: Bell, Arthur H.; Nelson, R. Lee & Richard, Paul H.
Partner: UNT Libraries Government Documents Department

Response of a Rotating Propeller to Aerodynamic Excitation

Description: The flexural vibration of a rotating propeller blade with clamped shank is analyzed with the object of presenting, in matrix form, equations for the elastic bending moments in forced vibration resulting from aerodynamic forces applied at a fixed multiple of rotational speed. Matrix equations are also derived which define the critical speeds end mode shapes for any excitation order and the relation between critical speed and blade angle. Reference is given to standard works on the numerical solution of matrix equations of the forms derived. The use of a segmented blade as an approximation to a continuous blade provides a simple means for obtaining the matrix solution from the integral equation of equilibrium, so that, in the numerical application of the method presented, the several matrix arrays of the basic physical characteristics of the propeller blade are of simple form, end their simplicity is preserved until, with the solution in sight, numerical manipulations well-known in matrix algebra yield the desired critical speeds and mode shapes frame which the vibration at any operating condition may be synthesized. A close correspondence between the familiar Stodola method and the matrix method is pointed out, indicating that any features of novelty are characteristic not of the analytical procedure but only of the abbreviation, condensation, and efficient organization of the numerical procedure made possible by the use of classical matrix theory.
Date: January 21, 1949
Creator: Arnoldi, Walter E.
Partner: UNT Libraries Government Documents Department

Investigation of X24C-2 10-Stage Axial-Flow Compressor, 2, Effect of Inlet-Air Pressure and Temperature of Performance

Description: Effect of inlet-air pressure and temperature on the performance of the X24-2 10-Stage Axial-Flow Compressor from the X24C-2 turbojet engine was evaluated. Speeds of 80, 89, and 100 percent of equivalent design speed with inlet-air pressures of 6 and 12 inches of mercury absolute and inlet-air temperaures of approximately 538 degrees, 459 degrees,and 419 degrees R ( 79 degrees, 0 degrees, and minus 40 degrees F). Results were compared with prior investigations.
Date: August 21, 1947
Creator: Finger, Harold B.; Schum, Harold J. & Buckner, Howard Jr.
Partner: UNT Libraries Government Documents Department

Measurements of Atmospheric Turbulence on Seattle-Alaska Airways

Description: For about the past year, American Airlines has been engaged in obtaining data on various uses of airborne radar under routine operating conditions. This work is under contract to the Navy Department, Bureau of Ships, and includes the investigation of radar as a navigational aid and terrain collision warning device and its use in icing and turbulence detection. In view of the work of the National Advisory Committee for Aeronautics on atmospheric turbulence, the NACA was requested to participate in the tests to the extent of obtaining and evaluating the turbulence data for use in the turbulence-detection phase of the work. Gust measurements and airborne radar observations were consequently obtained in February and March 1947 during routine flights of an American Airlines airplane on the Seattle-Alaska airways. Unfortunately, the weather conditions encountered during the flights gave no well-defined radar echoes and no comparison between radar indications end turbulence could be made. The gust data for the route, however, are of interest from an operational standpoint, and are presented herein for the information of the Navy Department in accordance with previous arrangements.
Date: October 21, 1947
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

General Characteristics of a Airspeed System using Fuselage Static Vents on a Swept-Wing Airplane

Description: Studies have been made by the NACA wing-flow method of the use of fuselage static orifices between the wing and tail of a swept-wing airplane for possible application to service airspeed installations. The tests were made at zero angle of attack. The results indicate that, although the maximum errors are large, these locations are usable from the consideration that the local Mach numbers at the locations studied are sensitive to variation of the true Mach number within the test Mach number range of 0.7 to 1.2. The maximum errors in Mach number in the subsonic range varied from zero for the most forward location to -0.05 for the most rearward location (indicated Mach number less than true). At Mach numbers above 1.0, the maximum errors were from 0.14 for the most forward location to 0.04 for the most rearward location.
Date: October 21, 1949
Creator: Johnston, J. Ford & OBryan, Thomas C.
Partner: UNT Libraries Government Documents Department

Evaluation of Gust and Draft Velocities from Flights of P-61C Airplanes within Thunderstorms June 11, 1947 to July 11, 1947 at Clinton County Army Air Field, Ohio

Description: 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 June 11, 1947 to July 11, 1947 are presented.
Date: January 21, 1948
Creator: Funk, Jack
Partner: UNT Libraries Government Documents Department

High-Speed Load Distribution on the Wing of a 3/16-Scale Model of a Scout-Bomber 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 a scout-bomber 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.
Date: August 21, 1947
Creator: Barnes, Robert H.
Partner: UNT Libraries Government Documents Department

Hydrodynamic characteristics of a low-drag, planing-tail flying-boat hull

Description: The hydrodynamic characteristics of a flying-boat incorporating a low-drag, planing-tail hull were determined from model tests made in Langley tank number 2 and compared with tests of the same flying boat incorporating a conventional-type hull. The planing-tail model, with which stable take-offs were possible for a large range of elevator positions at all center-of-gravity locations tested, had more take-off stability than the conventional model. No upper-limit porpoising was encountered by the planing-tail model. The maximum changes in rise during landings were lower for the planing-tail model than for the conventional model at most contact trims, an indication of improved landing stability for the planing-tail model. The hydrodynamic resistance of the planing-tail hull was lower than the conventional hull at all speeds, and the load-resistance ratio was higher for the planing-tail hull, being especially high at the hump. The static trim of the planing-tail hull was much higher than the conventional hull, but the variation of trim with speed during take-off was smaller.
Date: October 21, 1948
Creator: Suydam, Henry B.
Partner: UNT Libraries Government Documents Department

Analysis of heat and compressibility effects in internal flow systems and high-speed tests of a ram-jet system

Description: Report discussing an analysis has been made by the NACA of the effects of heat and compressibility in the flow through the internal systems of aircraft along with equations and charts are developed whereby the flow characteristics at key stations in a typical internal system may be readily obtained.
Date: July 21, 1942
Creator: Becker, John V & Baals, Donald D
Partner: UNT Libraries Government Documents Department