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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

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

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

Some yawing tests of a 1/30-scale model of the hull of the XPB2M-1 flying boat

Description: Report discusses the results of yawing tests on a model of the complete hull of the XPB2M-1. The tests indicated that there was a tendency toward directional instability in the vicinity of the hump. The researchers concluded that at a certain range, the curves of yawing moment are discontinuous, and this has led to difficulty in preliminary test flights.
Date: July 1943
Creator: Locke, F. W. S., Jr.
Partner: UNT Libraries Government Documents Department

Effect of forebody warp on the hydrodynamic qualities of a hypothetical flying boat having a hull length-beam ratio of 15

Description: Report of an investigation of the effect of forebody warp on the hydrodynamic qualities of a hypothetical flying boat with a hull length-beam ratio of 15 in smooth water and in waves. Warping the forebody planing bottom was found to appreciably increase the range of stable trim between the lower and upper trim limits of stability, although the center-of-gravity limits of stability were reduced.
Date: March 1949
Creator: Carter, Arthur W. & Weinstein, Irving
Partner: UNT Libraries Government Documents Department

Effect of hull length-beam ratio on the hydrodynamic characteristics of flying boats in waves

Description: Report presenting an investigation of the take-off and landing behavior in waves of models of a hypothetical flying boat with hull length-beam ratios of 6 and 15. The flying boat had a design gross weight of 75,000 pounds, a wing loading of 41.1 pounds per square foot, and a power loading of 11.5 pounds per brake horsepower for take-off. Results regarding the landing behavior, spray characteristics, and taxiing and take-off behavior are provided.
Date: January 1949
Creator: Carter, Arthur W.
Partner: UNT Libraries Government Documents Department

An investigation of the spray characteristics of a jet-powered dynamic model of the drag flying boat with a vee tail : TED No. NACA DE 328

Description: An investigation was made of the spray characteristics of a jet-powered dynamic model of the Bureau of Aeronautics DR 56 flying-boat design with a vee tail. A limited investigation was made to determine the effect of the change in tail design on the take-off and landing behavior in smooth water and in waves 8 feet high (full size).
Date: February 28, 1951
Creator: Carter, Arthur W.
Partner: UNT Libraries Government Documents Department

Hydrodynamic tests of a 1/10-size model of the hull of the Latecoere 521 flying boat: NACA model 83

Description: From Summary: "A 1/10-size model of the hull of the French flying boat Latecoere 521 was tested in the NACA tank. This model is one of a series of models of the hulls of actual flying boats of both foreign and domestic type that are being tested in the NACA tank to provide information regarding the water characteristics of a variety of forms of hull and to illustrate the development of present-day types of flying boat. The lines and the offsets of the hull were obtained from the manufacturer through the Paris office of the NACA."
Date: December 1941
Creator: Olson, Roland E. & Lina, Lindsay J.
Partner: UNT Libraries Government Documents Department

Water landing investigation of a model having a heavy beam loading and a 30 degree angle of dead rise

Description: Results presenting testing of a model with heavy beam loading and an angle of dead rise of 30 degrees subjected to smooth-water impacts in the Langley impact basin. Testing was made at fixed trims of 6 degrees, 15 degrees, 30 degrees, and 45 degrees for a range of flight-path angles and consistent beam-loading coefficient. Time histories of horizontal and vertical displacements, vertical velocity, vertical acceleration, and pitching moment are provided.
Date: February 1950
Creator: Batterson, Sidney A. & McArver, A. Ethelda
Partner: UNT Libraries Government Documents Department

The hydrodynamic planing lift of four surfaces as measured in a 200-FPS free jet

Description: Report presenting hydrodynamic planing lifts obtained in a free jet at speeds from 80 to 200 fps for four planing surfaces. The surfaces tested included a flat plate, a longitudinally curved model, a cylinder, and a hydro-ski with a complex-shaped bottom. Lift data was analyzed to show the effect of speed, planing-surface configuration, trim, and wetted-length-beam ratio at high speeds.
Date: July 7, 1954
Creator: McGehee, John R.; Weinflash, Bernard & Pelz, Charles A.
Partner: UNT Libraries Government Documents Department

Effect of afterbody length and keel angle on minimum depth of step for landing stability and on take-off stability of a flying boat

Description: From Summary: "Tests were made to fill partly the need for information on the effect of afterbody dimensions on the hydrodynamic stability of a flying boat in smooth water. The dimensions investigated were depth of step, angle of afterbody keel, and length of afterbody. An analysis of the data showed that as either the afterbody length or keel angle was increased an accompanying increase in depth of step was required in order to maintain adequate landing stability."
Date: November 13, 1947
Creator: Olson, Roland E. & Land, Norman S.
Partner: UNT Libraries Government Documents Department