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The Effect of Air Jets Simulating Chines or Multiple Steps on the Hydrodynamic Characteristics of a Streamline Fuselage

Description: Memorandum presenting preliminary tests in order to determine the effect of forced ventilation on the hydrodynamic characteristics of a scale model of a streamline fuselage of a hypothetical transonic airplane. The forced ventilation consisted of air ejected at about 300 feet per second through small orifices distributed over the fuselage bottom in a series of patterns simulating chines or multiple steps. Results regarding resistance, effective hydrodynamic lift, trim, spray, and air flow are provided.
Date: January 7, 1949
Creator: Weinflash, Bernard
Partner: UNT Libraries Government Documents Department

A Generalized Theoretical and Experimental Investigation of the Motions and Hydrodynamic Loads Experienced by V-Bottom Seaplanes During Step-Landing Impacts

Description: Note presenting a theoretical investigation made of the motions and hydrodynamic loads experienced by V-bottom seaplanes during the course of a step-landing impact. In the analysis, the primary flow about the immersed portion of a keeled float or hull is considered to occur in transverse flow planes and the virtual-mass concept is applied to calculate the reaction of the water to the motion of the seaplane. The results are presented in the form of dimensionless curves which may be used to predict the behavior of V-bottom seaplanes at all instants during an impact as well as at the particular instants of maximum acceleration, maximum draft, and rebound.
Date: February 1948
Creator: Milwitzky, Benjamin
Partner: UNT Libraries Government Documents Department

A Generalized Theoretical Investigation of the Hydrodynamic Pitching Moments Experienced by V-Bottom Seaplanes During Step-Landing Impacts and Comparisons With Experiment

Description: Note presenting a theoretical investigation made of the hydrodynamic pitching moments experienced by V-bottom seaplanes during step-landing impacts. The entire immersion process is analyzed from the instant of initial contact until the seaplane rebounds from the water surface.
Date: June 1948
Creator: Milwitzky, Benjamin
Partner: UNT Libraries Government Documents Department

The Hydrodynamic Theory of Detonation

Description: "This report derives equations containing only directly measurable constants for the quantities involved in the hydrodynamic theory of detonation. The stable detonation speed, D, is revealed as having the lowest possible value in the case of positive material velocity, by finding the minimum of the Du curve (u denotes the speed of the gases of combustion). A study of the conditions of energy and impulse in freely suspended detonating systems leads to the disclosure of a rarefaction front traveling at a lower speed behind the detonation front; its velocity is computed" (p. 1).
Date: June 1939
Creator: Langweiler, Heinz
Partner: UNT Libraries Government Documents Department

Hydrodynamic Investigation of a Series of Hull Models Suitable for Small Flying Boats and Amphibians

Description: Note presenting the results of an investigation to obtain hydrodynamic information on a series of hull models suitable for small flying boats or amphibians of from 2000 to 5000 pounds gross weight. The series of hulls consisted of a basic hull with simple lines, and of plus and minus variations to the design in which the beam, stern-post angle, and afterbody length were altered. The results show that it is possible to design a hull with simple lines that will be suitable for small flying boats or amphibians.
Date: November 1951
Creator: Hugli, W. C., Jr. & Axt, W. C.
Partner: UNT Libraries Government Documents Department

Hydrodynamic Tests of Models of Seaplane Floats

Description: "This report contains the results of tank tests carried out at free trim on seventeen hulls and floats of various types. The data as to the weight on water, trim, and relative resistance for each model are plotted nondimensionally and are referenced both to the total weight and to the weight on water. Despite the fact that the experiments were not made systematically, a study of the models and of the test data permits nevertheless some general deductions regarding the forms of floats and their resistance" (p. 1).
Date: May 1935
Creator: Eula, Antonio
Partner: UNT Libraries Government Documents Department

Hydrodynamic Impact Loads of a -20 Degree Dead-Rise Inverted-V Model and Comparisons With Loads of a Flat-Bottom Model

Description: Note presenting a model with an inverted-V transverse shape and a dead-rise angle of -20 degrees as part of a study of hydrodynamic impact loads on chine-immersed bodies. A series of fixed-trim impacts of the inverted-V model were made in smooth water over a wide range of trim and initial flight-path angles at a beam-loading coefficient of 19.15 with a few impacts at beam-loading coefficients of 27.90 and 36.07. The data are presented in tables and in figures as variations of loads and motions (in coefficient form) with time, trim angle, and flight-path angle.
Date: August 1958
Creator: Edge, Philip M., Jr.
Partner: UNT Libraries Government Documents Department

The Boundary Layer as a Means of Controlling the Flow of Liquids and Gases

Description: According to one of the main propositions of the boundary layer theory the scarcely noticeable boundary layer may, under certain conditions, have a decisive influence on the form of the external flow by causing it to separate from the wing surface. These phenomena are known to be caused by a kind of stagnation of the boundary layer at the point of separation. The present report deals with similar phenomena. It is important to note that usually the cause (external interference) directly affects only the layer close to the wall, while its indirect effect extends to a large portion of the external flow.
Date: March 1930
Creator: Schrenk, Oskar
Partner: UNT Libraries Government Documents Department

A Theoretical Investigation of Hydrodynamic Impact Loads on Scalloped-Bottom Seaplanes and Comparisons With Experiment

Description: "An analytical method is presented for calculating the hydrodynamic impact loads and motions experienced by seaplane floats and hulls with scalloped (fluted) bottoms. The analysis treats vertical impact at zero trim in addition to the more general problem of the step impact of a seaplane at positive trim where the flight path is oblique to the keel and to the water surface. Also considered are the transformations required to represent impacts into waves" (p. 109).
Date: April 16, 1947
Creator: Milwitzky, Benjamin
Partner: UNT Libraries Government Documents Department

Effect of Carriage Mass Upon the Loads and Motions of a Prismatic Body During Hydrodynamic Impact

Description: Note presenting a theoretical derivation for the effect of a towing-carriage mass upon the general equations of motion for a prismatic body during a hydrodynamic impact. The equations can be used at any stage of the impact to determine the resulting loads and motions of the body, including the effect of a carriage mass. Results regarding a nonimmersed chine and an immersed chine are provided.
Date: March 1956
Creator: Markey, Melvin F.
Partner: UNT Libraries Government Documents Department

High-Speed Hydrodynamic Characteristics of a Flat Plate and 20 Degrees Dead-Rise Surface in Unsymmetrical Planing Conditions

Description: Note presenting the results of an investigation made to obtain the wetted areas, three components of planing forces, and the three components of moments acting on a 0 degree and a 20 degree dead-rise surface in high-speed, unsymmetrical planing conditions. The collected test data are presented in summary plots which are readily applicable for use in determining the lift, drag, side force, pitching moment, rolling moment, and yawing moment.
Date: June 1958
Creator: Savitsky, Daniel; Prowse, R. E. & Lueders, D. H.
Partner: UNT Libraries Government Documents Department

A Graphical Method for Interpolation of Specific Flying Boats From Collapsed Results of General Tests of Flying-Boat-Hull Models

Description: Note presenting a simple and rapid method for interpolating the hydrodynamic characteristics of specific flying boats from a chart presenting test results in collapsed form. The method is graphical and will allow interpolation of the hydrodynamic characteristics for any combination of load or aerodynamic characteristics. The charts consider the effect of wing and flap setting, effect of hull size, effect of wing size, effect of weight, and some miscellaneous data.
Date: January 1948
Creator: Locke, F. W. S., Jr.
Partner: UNT Libraries Government Documents Department

A Theoretical and Experimental Investigation of the Effects of Yaw on Pressures, Forces, and Moments During Seaplane Landings and Planing

Description: A theory for the side force, rolling moment, yawing moment, and pressure distribution during yawed landings and planing of seaplanes was developed. For the special case of the straight-sided wedge without chine immersion, the results of the theoretical analysis are presented in the form of generalized curves covering all step landing conditions. Experimental impact and planing data are presented for a prismatic wedge having an angle of dead rise of 22.5 degrees and are shown to be in reasonable agreement with the theoretical predictions.
Date: November 1952
Creator: Smiley, Robert F.
Partner: UNT Libraries Government Documents Department

Hydrodynamic Characteristics of a Low-Drag, Planing-Tail Flying Boat Hull

Description: Note presenting the hydrodynamic characteristics of a flying boat incorporating a low-drag, planing-tail hull as determined from model tests made in tank no. 2 and compared with tests of the same flying boat incorporating a conventional type of hull. The planing-tail model had a greater range of elevator deflection and center-of-gravity location for stable take-offs than did the conventional model.
Date: January 1952
Creator: Suydam, Henry B.
Partner: UNT Libraries Government Documents Department

Limited Hydrodynamic Investigation of a 1/15-Size Model of a Modified Nose-Inlet Multijet Water-Based Aircraft

Description: Memorandum presenting an investigation conducted to determine the effect on the low-speed resistance and spray characteristics and static transverse stability of a modification which extended the bow of a scale model of a nose-inlet transonic seaplane configuration. The investigation was made with and without tip floats. The change was found to result in a 50-percent reduction in the hump resistance, increased engine-inlet clearance, reduced low-speed spray and hull-side flow, and acceptable spray and resistance at 25-percent overload.
Date: February 3, 1956
Creator: McKann, Robert E. & Coffee, Claude W.
Partner: UNT Libraries Government Documents Department

Free Convection Under the Conditions of the Internal Problem

Description: Convection is called free is the stresses (including the normal pressure) to which the fluid is subjected at its boundaries do not perform mechanical work, that is, if all the boundaries of the fluid are stationary. The case where this is not true is termed forced convection. It corresponds to the action on the fluid of some mechanical suction pumping the fluid.
Date: April 1958
Creator: Ostroumov, G. A.
Partner: UNT Libraries Government Documents Department

The NACA impact basin and water landing tests of a float model at various velocities and weights

Description: The first data obtained in the United States under the controlled testing conditions necessary for establishing relationships among the numerous parameters involved when a float having both horizontal and vertical velocity contacts a water surface are presented. The data were obtained at the NACA impact basin. The report is confined to a presentation of the relationship between resultant velocity and impact normal acceleration for various float weights when all other parameters are constant. Analysis of the experimental results indicated that the maximum impact normal acceleration was proportional to the square of the resultant velocity, that increases in float weight resulted in decreases in the maximum impact normal acceleration, and that an increase in the flight-path angle caused increased impact normal acceleration.
Date: 1944
Creator: Batterson, Sidney A.
Partner: UNT Libraries Government Documents Department

The NACA impact basin and water landing tests of a float model at various velocities and weights

Description: Report presenting data obtained when a float with both horizontal and vertical velocity contact on a water surface. The report is confined to a presentation of the relationship between resultant velocity and impact normal acceleration for various float weights when all other parameters are constant.
Date: August 1944
Creator: Batterson, Sidney A.
Partner: UNT Libraries Government Documents Department

Preliminary tank tests of NACA hydro-skis for high-speed airplanes

Description: Report presenting the results from tank landing and take-off tests with a dynamic model of a hypothetical jet-propelled airplane equipped with NACA hydro-skis. Results regarding landing tests, take-off tests, and practical considerations for the creation of hydro-ski configurations are provided. The hydro-skis suitable for flush retraction into streamline fuselages do appear to offer a practical means of water take-offs and landings.
Date: November 26, 1947
Creator: Dawson, John R. & Wadlin, Kenneth L.
Partner: UNT Libraries Government Documents Department

Impingement of Water Droplets on an Ellipsoid with Fineness Ratio 5 in Axisymmetric Flow

Description: The presence of radomes and instruments that are sensitive to water films or ice formations in the nose section of all-weather aircraft and missiles necessitates a knowledge of the droplet impingement characteristics of bodies of revolution. Because it is possible to approximate many of these bodies with an ellipsoid of revolution, droplet trajectories about an ellipsoid of revolution with a fineness ratio of 5 were computed for incompressible axisymmetric air flow. From the computed droplet trajectories, the following impingement characteristics of the ellipsoid surface were obtained and are presented in terms of dimensionless parameters: (1) total rate of water impingement, (2) extent of droplet impingement zone, (3) distribution of impinging water, and (4) local rate of water impingement.
Date: March 1954
Creator: Dorsch, Robert G.; Brun, Rinaldo J. & Gregg, John L.
Partner: UNT Libraries Government Documents Department

Comparison of Experimental Hydrodynamic Impact Loads and Motions for a V-Step and a Transverse-Step Hydro-Ski

Description: Report presenting a comparison of the hydrodynamic impact loads and motions encountered in testing a V-step and a transverse-step flat-bottom hydro-ski with beam loadings of about 4.5. Testing occurred in smooth water over a range of velocities, flight-path angles, and fixed trims. Results regarding time histories of draft, vertical velocity, and vertical acceleration, impact lift coefficient, draft coefficient, and time coefficient for rebound are provided.
Date: February 2, 1954
Creator: Miller, Robert W.
Partner: UNT Libraries Government Documents Department

Some systematic model experiments on the porpoising characteristics of flying-boat hulls

Description: From Summary: "This report presents the results of systematic model experiments on the hydrodynamic characteristics of flying boats, aimed primarily at developing a comprehensive view of the factors influencing porpoising and of their relative importance. The experiments 'radiated' from a given reference ship; they embrace changes, over reasonably wide ranges, in the value of each of a number of variables, treated independently. The experimental results are summarized in a series of 25 figures, each of which gives the complete data for all the modifications of one variable."
Date: June 1943
Creator: Davidson, Kenneth S. M. & Locke, F. W. S., Jr.
Partner: UNT Libraries Government Documents Department

Some systematic model experiments of the bow-spray characteristics of flying-boat hulls operating at low speeds in waves

Description: Report discusses the results of testing on several models of flying boats, the XPB2M-1, the XPBB-1, the JRM-1, and 11 other models to determine the effect of bow form on the amount of spray thrown onto the windshield of a flying boat in rough water. Several recommendations for reducing the height and volume of spray are provided. Any change in the hull form that softens the impact between the hull and waves seems to reduce the spray.
Date: December 1943
Creator: Locke, F. W. S., Jr.
Partner: UNT Libraries Government Documents Department