Theoretical Prediction of Pressure Distributions on Nonlifting Airfoils at High Subsonic Speeds (open access)

Theoretical Prediction of Pressure Distributions on Nonlifting Airfoils at High Subsonic Speeds

"Theoretical pressure distributions on nonlifting circular-arc airfoils in two-dimensional flows with high subsonic free-stream velocity are found by determining approximate solutions, through an iteration process, of an integral equation for transonic flow proposed by Oswatitsch. The integral equation stems directly from the small-disturbance theory for transonic flow. This method of analysis possesses the advantage of remaining in the physical, rather than the hodograph, variable and can be applied in airfoils having curved surfaces" (p. 1).
Date: November 19, 1953
Creator: Spreiter, John R. & Alksne, Alberta
System: The UNT Digital Library
An Analysis of the Effects of Aeroelasticity on Static Longitudinal Stability and Control of a Swept-Wing Airplane (open access)

An Analysis of the Effects of Aeroelasticity on Static Longitudinal Stability and Control of a Swept-Wing Airplane

From Introduction: "The results of the aforementioned study are presented in this report together with the method of analysis employed. The net stability change is shown together with the individual contributions due to flexibility of wing, tail, and fuselage, both including and neglecting the effect of inertial loads."
Date: March 19, 1951
Creator: Skoog, Richard B.
System: The UNT Digital Library
The hydrodynamic characteristics of modified rectangular flat plates having aspect ratios of 1.00, 0.25, and 0.125 and operating near a free water surface (open access)

The hydrodynamic characteristics of modified rectangular flat plates having aspect ratios of 1.00, 0.25, and 0.125 and operating near a free water surface

Report presents the results of an investigation conducted to determine the hydrodynamic forces and moments acting on modified rectangular flat plates with aspect ratios of 1.00, 0.25, and 0.125 mounted on a single strut and operating at several depths of submersion. A simple method has been developed by modification of Falkner's vortex-lattice theory which enables the prediction of the lift characteristics in unseparated flow at large depths. This method shows good agreement with experimental data from the present tests and with aerodynamic data at all angles investigated for aspect ratios of 1.00 and 0.25 and at angles up to 16 degrees for aspect ratio 0.125. Above 16 degrees for aspect ratio 0.125, the predicted lift proved too high.
Date: January 19, 1954
Creator: Wadlin, Kenneth L.; Ramsen, John A. & Vaughan, Victor L., Jr.
System: The UNT Digital Library
The near noise field of static jets and some model studies of devices for noise reduction (open access)

The near noise field of static jets and some model studies of devices for noise reduction

An experimental study is presented of the pressure fluctuations near jet exhaust streams made during unchoked operation of a turbojet engine and a 1-inch-diameter high-temperature model jet and during choked operation of various sizes of model jets with unheated air. The tests for unchoked operation indicate a random spectrum of rather narrow band width which varies in frequency content with axial position along the jet. Pressure surveys from the model tests along lines parallel to the 15 degree jet boundary indicate that the station of greatest pressure fluctuations is determined by the jet velocity and the radial distance, with a tendency of the maximum to shift downstream as either parameter is increased.
Date: February 19, 1954
Creator: Lassiter, Leslie W. & Hubbard, Harvey H.
System: The UNT Digital Library
Method for Calculation of Laminar Heat Transfer in Air Flow Around Cylinders of Arbitrary Cross Section (Including Large Temperature Differences and Transpiration Cooling) (open access)

Method for Calculation of Laminar Heat Transfer in Air Flow Around Cylinders of Arbitrary Cross Section (Including Large Temperature Differences and Transpiration Cooling)

"The solution of heat-transfer problems has become vital for many aeronautical applications. The shapes of objects to be cooled can often be approximated by cylinders of various cross sections with flow normal to the axis as, for instance heat transfer on gas-turbine blades and on air foils heated for deicing purposes. A laminar region always exists near the stagnation point of such objects. A method previously presented by E. R. G. Eckert permits the calculation of local heat transfer around the periphery of cylinders of arbitrary cross section in the laminar region for flow of a fluid with constant property values with an accuracy sufficient for engineering purposes" (p. 223).
Date: March 19, 1952
Creator: Eckert, E. R. G. & Livingood, John N. B.
System: The UNT Digital Library
Reciprocity relations in aerodynamics (open access)

Reciprocity relations in aerodynamics

"Reverse flow theorems in aerodynamics are shown to be based on the same general concepts involved in many reciprocity theorems in the physical sciences. Reciprocal theorems for both steady and unsteady motion are found as a logical consequence of this approach. No restrictions on wing plan form or flight Mach number are made beyond those required in linearized compressible-flow analysis" (p. 253).
Date: February 19, 1952
Creator: Heaslet, Max A. & Spreiter, John R.
System: The UNT Digital Library
Some Effects of Nonlinear Variation in the Directional-Stability and Damping-in-Yawing Derivatives on the Lateral Stability of an Airplane (open access)

Some Effects of Nonlinear Variation in the Directional-Stability and Damping-in-Yawing Derivatives on the Lateral Stability of an Airplane

"A theoretical investigation has been made to determine the effect of nonlinear stability derivatives on the lateral stability of an airplane. Motions were calculated on the assumption that the directional-stability and the damping-in-yawing derivatives are functions of the angle of sideslip. The application of the Laplace transform to the calculation of an airplane motion when certain types of nonlinear derivatives are present is described in detail" (p. 1009).
Date: September 19, 1950
Creator: Sternfield, Leonard
System: The UNT Digital Library
The Langley annular transonic tunnel (open access)

The Langley annular transonic tunnel

Report describes the development of the Langley annular transonic tunnel, a facility in which test Mach numbers from 0.6 to slightly over 1.0 are achieved by rotating the test model in an annular passage between two concentric cylinders. Data obtained for two-dimensional airfoil models in the Langley annular transonic tunnel at subsonic and sonic speeds are shown to be in reasonable agreement with experimental data from other sources and with theory when comparisons are made for nonlifting conditions or for equal normal-force coefficients rather than for equal angles of attack. The trends of pressure distributions obtained from measurements in the Langley annular transonic tunnel are consistent with distributions calculated for Prandtl-Meyer flow.
Date: January 19, 1953
Creator: Habel, Louis W.; Henderson, James H. & Miller, Mason F.
System: The UNT Digital Library
Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow (open access)

Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow

From Introduction: "This report is concerned with the derivation of expressions for the velocity potential and associated forces and moments for oscillating triangular wings in supersonic flow. The purpose of the present report is to make use of the expanded form of the velocity potential to obtain the forces and moments, based on the first terms of this potential, for a rigid triangular wing performing vertical and pitching sinusoidal oscillations in mixed supersonic flow."
Date: June 19, 1951
Creator: Watkins, Charles E. & Berman, Julian H.
System: The UNT Digital Library
An evaluation of four experimental methods for measuring mean properties of a supersonic turbulent boundary layer (open access)

An evaluation of four experimental methods for measuring mean properties of a supersonic turbulent boundary layer

From Summary: "Surveys were made through a turbulent boundary layer on a flat plate by means of a pitot probe, an x-ray densitometer, and hot-wire and cold-wire probes. Results from these surveys were analyzed to determine (a) the reliability of the basic data and hence the methods by which they were obtained, and (b) how well the actual distributions of properties in the boundary layer compare with those commonly assumed in semiempirical and theoretical analyses. All surveys were made at the same longitudinal station on the flat plate. The tests were conducted in a an 8- by 8-inch supersonic nozzle. The free-stream Mach number was 3.03 and the Reynolds number was approximately 210,000 based on boundary-layer thickness."
Date: April 19, 1956
Creator: Nothwang, George J.
System: The UNT Digital Library
Method and Graphs for the Evaluation of Air-Induction Systems (open access)

Method and Graphs for the Evaluation of Air-Induction Systems

"Graphs have been developed for rapid evaluation of air-induction systems from considerations of their aerodynamic-performance parameters in combination with power-plant characteristics. The graphs cover the range of supersonic Mach numbers to 3.0. Examples are presented for an air-induction system and engine combination of two Mach numbers and two altitudes in order to illustrate the method and application of the graphs" (p. 793).
Date: February 19, 1952
Creator: Brajnikoff, George B.
System: The UNT Digital Library