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The effects of yawing thin pointed wings at supersonic speeds

Description: 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."
Date: September 1947
Creator: Evvard, John C.
Partner: UNT Libraries Government Documents Department

A linearized solution for time-dependent velocity potentials near three-dimensional wings at supersonic speeds

Description: Report presenting a source-distribution method for deriving a solution for the time-dependent surface velocity potential of thin finite wings at supersonic speeds. It is illustrated by evaluating the upwash over the tip of an arbitrary-plan-boundary wing with a supersonic and subsonic leading edge.
Date: September 1948
Creator: Evvard, John C.
Partner: UNT Libraries Government Documents Department

Theoretical distribution of lift on thin wings at supersonic speeds (An extension)

Description: Report presenting a derivation of a point-source method based on the linearized theory for obtaining the pressure coefficient on thin wings at supersonic speeds. The analysis is continued to formulate the velocity potential for regions influenced by so-called subsonic trailing edges.
Date: May 1948
Creator: Evvard, John C.
Partner: UNT Libraries Government Documents Department

Theoretical lift distribution and upwash velocities for thin wings at supersonic speeds

Description: Report presenting a method for calculating the upwash-velocity component in the vicinity of thin wings at supersonic speeds. The method is applied to obtain an expression for the upwash over wing tips of fairly general plan form and profile.
Date: November 1947
Creator: Evvard, John C. & Turner, L. Richard
Partner: UNT Libraries Government Documents Department

Graphical method of obtaining theoretical lift distributions on thin wings at supersonic speeds

Description: Report presenting a graphical method for calculating the linearized lift distribution on thin wings at supersonic speeds. It can be applied to all wing regions except those influenced by interacting flow fields off the wing-plan boundaries.
Date: August 1948
Creator: Cohen, Clarence B. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

Distribution of wave drag and lift in the vicinity of wing tips at supersonic speeds

Description: 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."
Date: July 1947
Creator: Evvard, John C.
Partner: UNT Libraries Government Documents Department

Criterions for prediction and control of ram-jet flow pulsations

Description: Report presenting the results of a theoretical and experimental study of ramjet diffuser flow pulsing, commonly referred to as a buzz condition, with and without combustion. The acoustical resonance properties of ram jets are an important factor in establishing the frequency of diffuser flow pulsations.
Date: May 16, 1951
Creator: Sterbentz, William H. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

Criterions for prediction and control of ram-jet flow pulsations

Description: Report presenting the results of a theoretical and experimental study of ramjet diffuser flow pulsing, commonly referred to as a buzz condition, with and without combustion. The acoustical resonance properties of ram jets are an important factor in establishing the frequency of diffuser flow pulsations.
Date: August 1955
Creator: Sterbentz, William H. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

The use of perforated inlets for efficient supersonic diffusion

Description: 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.
Date: June 25, 1947
Creator: Evvard, John C. & Blakey, John W.
Partner: UNT Libraries Government Documents Department

Three-dimensional supersonic nozzles and inlets of arbitrary exit cross section

Description: From Summary: "A method is presented for obtaining three-dimensional unsymmetric supersonic nozzles and inlets from known axisymmetric flows. Stream-lines bounding the desired exit shape are traced through the known basic flow solution to give the required unsymmetric wall contours. Several examples are given."
Date: April 1952
Creator: Evvard, John C. & Maslen, Stephen H.
Partner: UNT Libraries Government Documents Department

A correlation of the effects of compression ratio and inlet-air temperature on the knock limits of aviation fuels in a CFR engine 1

Description: Report presenting a method of correlating the effects of compression ratio and inlet-air temperature on the knock limits of aviation fuels. Knock-limited performance tests of several fuels were run to check the method.
Date: May 1945
Creator: Evvard, John C. & Branstetter, J. Robert
Partner: UNT Libraries Government Documents Department

A correlation of the effects of compression ratio and inlet-air temperature on the knock limits of aviation fuels in a CFR engine 2

Description: Report presenting the knock-limited performance of nine fuels comprising isolated members of four classes of hydrocarbons in the form of three-dimensional plots of fuel-air ratio, compression temperature, and compression-air density.
Date: June 1946
Creator: Alqusit, Henry E.; O'Dell, Leon & Evvard, John C.
Partner: UNT Libraries Government Documents Department

Knock-limited performance of several internal coolants

Description: Report presenting the effect of internal cooling on the knock-limited performance of AN-F-28 fuel in a CFR engine with the following internal coolants: water, methyl alcohol-water mixture, ammonia-methyl alcohol-water mixture, monomethyllamine-water mixture, dimethylamine-water mixture, and trimethylamine-water mixture.
Date: February 1944
Creator: Bellman, Donald R. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

Knock-limited performance of several internal coolants

Description: The effect of internal cooling on the knock-limited performance of an-f-28 fuel was investigated in a CFR engine, and the following internal coolants were used: (1) water, (2), methyl alcohol-water mixture, (3) ammonia-methyl alcohol-water mixture, (4) monomethylamine-water mixture, (5) dimethylamine-water mixture, and (6) trimethylamine-water mixture. Tests were run at inlet-air temperatures of 150 degrees and 250 degrees F. to indicate the temperature sensitivity of the internal-coolant solutions.
Date: February 1, 1944
Creator: Bellman, Donald R. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

Preignition-limited performance of several fuels

Description: Preignition-limited performance data were obtained on a supercharged CFR engine at two sets of operating conditions over a wide range of fuel-air ratios to determine the preignition characteristics for the following five fuels: s-3 reference fuel, s-3 plus 4 ml. tel per gallon, afd-33(140-p), benzene, and diisobutylene. Maximum thermal-plug temperatures at constant intake-air pressures were also determined to correlate the preignition characteristics of each fuel with its ability to increase general engine-temperature levels. Additional runs were made to compare the preignition-limited performance of triptane, triptane plus 4 ml. tel per gallon, and an-f-28r fuel.
Date: October 1, 1944
Creator: Male, Donald W. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

Knock-limited power outputs from a CFR engine using internal coolants 2: six aliphatic amines

Description: Report presenting an investigation to determine the knock-limited performance of AN-F-28, Amendment-2, fuel in a DCFR engine when water solutions of the following aliphatic amines were added as internal coolants: monomethylamine, dimethylamine, ethylendiamine, diethylamine, triethylamine, and butylamine. Results regarding the mean effective pressure, indicated specific fuel competition, indicated specific liquid consumption, and knock-limited inlet-air pressure plotted against fuel-air ratio are presented for each fuel and amine combination.
Date: October 1945
Creator: Bellman, Donald R.; Moeckel, W. E. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

Knock-limited power outputs from a CFR engine using internal coolants 1: monomethylamine and dimethylamine

Description: Report presenting an investigation to determine the knock-limited power obtainable by injecting water solutions of monomethylamine and dimethylamine as internal coolants into a CFR engine using AN-F-28, Amendment-2, fuel.
Date: December 1944
Creator: Bellman, Donald R.; Moeckel, W. E. & Evvard, John C.
Partner: UNT Libraries Government Documents Department

A relation between knock-limited or preignition-limited air-fuel ratio at lean mixtures and fuel-air ratio at rich mixtures

Description: Report presenting a derivation to show that, if the air-fuel ratio at lean mixtures is plotted against the fuel-air ratio at rich mixtures for identical values of the knock-limited indicated mean effective pressure on each side of the minimum indicated-mean-effective-pressure point, a straight line should result.
Date: November 1945
Creator: Evvard, John C.
Partner: UNT Libraries Government Documents Department

Use of source distributions for evaluating theoretical aerodynamics of thin finite wings at supersonic speeds

Description: From Summary: "A series of publications on the source-distribution methods for evaluating the aerodynamics of thin wings at supersonic speeds is summarized, extended, and unified. Included in the first part are the deviations of: (a) the linearized partial-differential equation for unsteady flow at a substantially constant Mach number. b) The source-distribution solution for the perturbation-velocity potential that satisfies the boundary conditions of tangential flow at the surface and in the plane of the wing; and (c) the integral equation for determining the strength and the location of sources to describe the interaction effects (as represented by upwash) of the bottom and top wing surfaces through the region between the finite wing boundary and the foremost Mach wave. The second part deals with steady-state thin-wing problems. The third part of the report approximates the integral equation for unsteady upwash and includes a solution of approximate equation. Expressions are then derived to evaluate the load distributions for time-dependent finite-wing motions."
Date: June 17, 1949
Creator: Evvard, John C.
Partner: UNT Libraries Government Documents Department

An estimation of the internal-cooling requirements of an aircraft-engine cylinder when using oxygen boost

Description: Report discusses a method developed to estimate the quantities of internal coolants required to prevent overheating of the aircraft cylinder when oxygen boost is applied. The formula and calculations related to inlet-air pressure, added oxygen, added water, added nitrogen, and total fluid weight are detailed.
Date: November 1944
Creator: Evvard, John C. & Moeckel, W. E.
Partner: UNT Libraries Government Documents Department

Knock-limited blending characteristics of blends of triptane and 28-R aviation fuel

Description: From Summary: "F-3 and F-4 knock data are presented for blends of 0, 20, 40, 60, and 80 percent by volume of triptane in 28-R reference fuel plus approximately 4.6 ml TEL per gallon in the final blends. For comparison of knock-limited performance, 28-R reference fuel containing 2.7 percent by volume of xylidines and leaded to 6 ml TEL per gallon is included. In order to provide information on temperature sensitivities, two sets of modified conditions were used in addition to the standard F-4 engine conditions."
Date: April 1944
Creator: Evvard, John C.; Imming, Harry S. & Genco, Russell S.
Partner: UNT Libraries Government Documents Department

Investigation of a variable Mach number supersonic tunnel with nonintersecting characteristics

Description: Report presenting a method for the design of supersonic-wind-tunnel nozzles that produce uniform flow over a continuously variable Mach number range without the use of flexible walls. Experimental results from a preliminary investigation of the tunnel are included, including calibration survey of flow, Mach number distributions, and pressure gradients are provided.
Date: November 15, 1948
Creator: Evvard, John C. & Wyatt, DeMarquis D.
Partner: UNT Libraries Government Documents Department

The use of perforated inlets for efficient supersonic diffusion

Description: 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.
Date: September 1956
Creator: Evvard, John C. & Blakey, John W.
Partner: UNT Libraries Government Documents Department