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 Decade: 1940-1949
 Year: 1947
 Month: February
 Collection: National Advisory Committee for Aeronautics Collection
Aerodynamic Characteristics at High Speeds of Full-Scale Propellers having Different Shank Designs

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

Date: February 13, 1947
Creator: Maynard, Julian D.
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, ...
Contributing 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

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

Date: February 10, 1947
Creator: Krebs, Richard P
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Application of the analogy between water flow with a free surface and two-dimensional compressible gas flow

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

Date: February 1, 1947
Creator: Orlin, W James
Description: The theory of hydraulic analogy, that is, the analogy between water flow with a free surface and two-dimensional compressible gas flow and the limitations and conditions of the analogy are discussed. A test run was made using the hydraulic analogy as applied to the flow about circular cylinders at various diameters at subsonic velocities extending to the super critical range. The apparatus and techniques used in this application are described and criticized. Reasonably satisfactory agreement of pressure distributions and flow fields existed between water and airflow about corresponding bodies. This agreement indicated the possibility of extending experimental compressibility research by new methods.
Contributing Partner: UNT Libraries Government Documents Department
Bearing strength of some sand-cast magnesium alloys

Bearing strength of some sand-cast magnesium alloys

Date: February 1, 1947
Creator: Moore, R L
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Calculations of the Supersonic Wave Drag of Nonlifting Wings with Arbitrary Sweepback and Aspect Ratio: Wings Swept Behind the Mach Lines

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

Date: February 21, 1947
Creator: Harmon, Sidney M
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, ...
Contributing Partner: UNT Libraries Government Documents Department
Charts showing relations among primary aerodynamic variables for helicopter-performance estimation

Charts showing relations among primary aerodynamic variables for helicopter-performance estimation

Date: February 1, 1947
Creator: Talkin, Herbert W
Description: In order to facilitate solutions of the general problem of helicopter selection, the aerodynamic performance of rotors is presented in the form of charts showing relations between primary design and performance variables. By the use of conventional helicopter theory, certain variables are plotted and other variables are considered fixed. Charts constructed in such a manner show typical results, trends, and limits of helicopter performance. Performance conditions considered include hovering, horizontal flight, climb, and ceiling. Special problems discussed include vertical climb and the use of rotor-speed-reduction gears for hovering.
Contributing Partner: UNT Libraries Government Documents Department
A Comparison of the Lateral Motion Calculated for Tailless and Conventional Airplanes

A Comparison of the Lateral Motion Calculated for Tailless and Conventional Airplanes

Date: February 1, 1947
Creator: Harper, Charles W.
Description: Theoretical analysts of lateral dynamic motion of tailless and conventional airplanes was made for fighter and heavy transport. Their reactions to a lateral gust and control power required by each for simple maneuvers were determined and compared. Both types of airplanes require almost identical aileron control power to perform a given maneuver; tailless airplane requires about 1-2 to 1-3 directional control power of conventional airplane. Tailless airplane also shows greatest displacement for a given disturbance and has least damping in oscillatory mode.
Contributing 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

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

Date: February 13, 1947
Creator: Bunnell, Mort V.
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.
Contributing Partner: UNT Libraries Government Documents Department
Computed performance of a composite engine based on experimental data for a single-cylinder conventional aircraft engine converted to compression-ignition operation

Computed performance of a composite engine based on experimental data for a single-cylinder conventional aircraft engine converted to compression-ignition operation

Date: February 3, 1947
Creator: Mccoy, J Arnold
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Computed Temperature Distribution and Cooling of Solid Gas-Turbine Blades

Computed Temperature Distribution and Cooling of Solid Gas-Turbine Blades

Date: February 11, 1947
Creator: Reuter, J. George
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).
Contributing Partner: UNT Libraries Government Documents Department
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