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General algebraic method applied to control analysis of complex engine types (open access)

General algebraic method applied to control analysis of complex engine types

"A general algebraic method of attack on the problem of controlling gas-turbine engines having any number of independent variables was utilized employing operational functions to describe the assumed linear characteristics for the engine, the control, and the other units in the system. Matrices were used to describe the various units of the system, to form a combined system showing all effects, and to form a single condensed matrix showing the principal effects. This method directly led to the conditions on the control system for noninteraction so that any setting disturbance would affect only its corresponding controlled variable" (p. 581).
Date: April 25, 1949
Creator: Boksenbom, Aaron S. & Hood, Richard
System: The UNT Digital Library
Theoretical analysis of various thrust-augmentation cycles for turbojet engines (open access)

Theoretical analysis of various thrust-augmentation cycles for turbojet engines

"The results of analytical studies of tail-pipe-burning, water-injection, and bleedoff methods of thrust augmentation are presented that provide an insight into the operating characteristics of these augmentation methods and summarizes the performance that may be obtained when applied to a typical turbojet engine. A brief description of the principles of operation of each augmentation method is given, together with curves that illustrate the effects of the principal design and operating variables of the augmentation system on the thrust and the liquid consumption of the engine. The necessity of designing tail-pipe burners with a low burner-inlet velocity, a low burner drag, and a high diffuser efficiency in order to obtain a high thrust augmentation and to minimize the loss in engine performance during nonburning operation is illustrated" (p. 593).
Date: September 2, 1949
Creator: Lundin, Bruce T.
System: The UNT Digital Library
An introduction to the physical aspects of helicopter stability (open access)

An introduction to the physical aspects of helicopter stability

In order to provide engineers interested in rotating-wing aircraft, but with no specialized training in stability theory, some understanding of the factors that influence the flying qualities of the helicopter, an explanation is made of both the static stability and the stick-fixed oscillation in hovering and forward flight in terms of fundamental physical quantities. Three significant stability factors -- static stability with angle of attack, static stability with speed, and damping due to a pitching or rolling velocity -- are explained in detail.
Date: September 19, 1949
Creator: Gessow, Alfred & Amer, Kenneth B.
System: The UNT Digital Library
Fundamental effects of aging on creep properties of solution-treated low-carbon N-155 alloy (open access)

Fundamental effects of aging on creep properties of solution-treated low-carbon N-155 alloy

A method is developed whereby the fundamental mechanisms are investigated by which processing, heat treatment, and chemical composition control the properties of alloys at high temperatures. The method used metallographic examination -- both optical and electronic --studies of x-ray diffraction-line widths, intensities, and lattice parameters, and hardness surveys to evaluate fundamental structural conditions. Mechanical properties at high temperatures are then measured and correlated with these measured structural conditions. In accordance with this method, a study was made of the fundamental mechanism by which aging controlled the short-time creep and rupture properties of solution-treated low-carbon n-155 alloy at 1200 degrees F.
Date: January 18, 1949
Creator: Frey, D. N.; Freeman, J. W. & White, A. E.
System: The UNT Digital Library
Correlation of Physical Properties With Molecular Structure for Some Dicyclic Hydrocarbons Having High Thermal-Energy Release Per Unit Volume (open access)

Correlation of Physical Properties With Molecular Structure for Some Dicyclic Hydrocarbons Having High Thermal-Energy Release Per Unit Volume

"As part of a program to study the correlation between molecular structure and physical properties of high-density hydrocarbons, the net heats of combustion, melting points, boiling points, densities, and kinematic viscosities of some hydrocarbons in the 2-n-alkylbiphenyl, 1,1-diphenylalkane, diphenylalkane, 1,1-dicyclohexylalkane, and dicyclohexylalkane series are presented" (p. 55).
Date: June 20, 1949
Creator: Wise, P. H.; Serijan, K. T. & Goodman, I. A.
System: The UNT Digital Library
An Analysis of Supersonic Aerodynamic Heating With Continuous Fluid Injection (open access)

An Analysis of Supersonic Aerodynamic Heating With Continuous Fluid Injection

From Introduction: "The aerodynamic heating problem assumes considerable importance at high-supersonic speeds. Sanger and Bredt (reference 1) have calculated the high-speed aerodynamic forces and equilibrium surface temperature at extremely high altitudes where the molecular mean free path is large (free-molecule-flow region) compared with a characteristic body dimension. The theoretical investigation of Lees (reference 2) on the stability of the laminar boundary layer in compressible flow indicates that the laminar boundary layer is completely stable at all Reynolds numbers at supersonic speeds for a sufficiently low ratio of surface temperature to stream temperature."
Date: September 29, 1949
Creator: Klunker, E. B. & Ivey, H. Reese
System: The UNT Digital Library