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Theoretical analysis of hydrodynamic impact of a prismatic float having freedom in trim

Description: From Summary: "Equations which include freedom in trim are derived for hydrodynamic impact of a non-chine-immersed, prismatic float forebody having a V-bottom and a transverse step. These equations are an extension of previously published fixed-trim theory, and a method of solution is indicated by which time histories of vertical, horizontal, and angular displacement, velocity, and acceleration can be obtained. Comparisons of specific solutions of the equations with corresponding fixed-trim solutions are presented."
Date: June 1952
Creator: Miller, Robert W.
Partner: UNT Libraries Government Documents Department

Hydrodynamic Characteristics of Missiles Launched Under Water

Description: Report presenting some of the hydrodynamic problems associated with launching an air missile from underwater. The results of an experiment with models are also provided, including deviation angle, effect of forward speed of the submarine, curved path of the missile, and potential environmental disruptions.
Date: June 27, 1958
Creator: Dawson, John R.
Partner: UNT Libraries Government Documents Department

Hydrodynamic impact of a system with a single elastic mode I : theory and generalized solution with an application to an elastic airframe

Description: Solutions of impact of a rigid prismatic float connected by a massless spring to a rigid upper mass are presented. The solutions are based on hydrodynamic theory which has been experimentally confirmed for a rigid structure. Equations are given for defining the spring constant and the ratio of the sprung mass to the lower mass so that the two-mass system provides representation of the fundamental mode of an airplane wing. The forces calculated are more accurate than the forces which would be predicted for a rigid airframe since the effect of the fundamental mode on the hydrodynamic force is taken into account. In a comparison of the theoretical data with data for a severe flight-test landing impact, the effect of the fundamental mode on the hydrodynamic force is considered and response data are compared with experimental data.
Date: March 17, 1947
Creator: Mayo, Wilbur L.
Partner: UNT Libraries Government Documents Department

Hydrodynamic tests for determining the take-off characteristics of seaplanes

Description: The resistance of water, even at low speeds, may be such as to render it impossible to take off. For this type of aircraft, it is therefore especially important to determine the take-off characteristics. A new and simple graphical method is given and appears to be the only one for the complete solution of the problem.
Date: May 1923
Creator: Verduzio, R.
Partner: UNT Libraries Government Documents Department

Effects of sweepback and taper on the force and cavitation characteristics of aspect-ratio-4 hydrofoils

Description: Report presenting an investigation to determine the effects of sweepback and taper ratio on the cavitation and hydrodynamic force characteristics of hydrofoils. Four hydrofoils were used, all of which had different taper ratios and degrees of sweep. Results regarding the effect of cavitation on hydrodynamic characteristics, effect of sweep on cavitation and force characteristics, effect of taper ratio on cavitation and force characteristics, and a comparison with wind-tunnel data are provided.
Date: December 2, 1952
Creator: King, Douglas A. & Land, Norman S.
Partner: UNT Libraries Government Documents Department

Preliminary Tests in the NACA Tank to Investigate the Fundamental Characteristics of Hydrofoils

Description: A preliminary investigation made to study the hydrodynamic properties and general behavior of simple hydrofoils. Six plain, rectangular hydrofoils were tested in a tank at various speeds, angles of attack, and depths below the water surface. The results are presented as curves of the lift and drag coefficients plotted against speed for various angles of attack and depths for which the hydrofoils were tested.
Date: September 1940
Creator: Ward, Kenneth E. & Land, Norman S.
Partner: UNT Libraries Government Documents Department

An experimental investigation of the scale relations for the impinging water spray generated by a planing surface

Description: Report presenting an experimental investigation to determine the scale effects of the forces from water spray generated by a flat rectangular planing surface and impinging on a collector plate representative of an aerodynamic surface or other part of a water-based airplane. Lift and drag forces on the flat rectangular planing surface and the spray-collector plate were measured.
Date: February 1956
Creator: McBride, Ellis E.
Partner: UNT Libraries Government Documents Department

Landing Characteristics in Waves of Three Dynamic Models of Flying Boats

Description: Powered models of three different flying boats were landed in oncoming wave of various heights and lengths. The resulting motions and acceleration were recorded to survey the effects of varying the trim at landing, the deceleration after landing, and the size of the waves. One of the models had an unusually long afterbody. The data for landing with normal rates of deceleration indicated that the most severe motions and accelerations were likely to occur at some period of the landing run subsequent to the initial impact.
Date: May 7, 1947
Creator: Benson, James M.; Havens, Robert F. & Woodward, David R.
Partner: UNT Libraries Government Documents Department

Rough-water Landings of a 0.1-Size Powered Dynamic Model of the XP5Y-1 Flying Boat with Two Types of Afterbody - Langley Tank Model 228 (TED No. NACA DE309)

Description: A 0.1-size powered dynamic model of a large, high-speed flying boat was landed in Langley tank no. 1 into oncoming waves 4 feet high (full size). The model was tested with two afterbodies of differing lengths (4.12 and 6.63 beams). The short afterbody had a constant angle of dead rise of 22.5deg and a keel angle of 6.5deg. The long afterbody had warped dead rise and a keel angle of 8.5deg. The vertical accelerations were slightly greater and the maximum angular accelerations and maxim= trims were slightly less for the model with the long afterbody than for the model with -the short afterbody. A wave length of 210 feet (full size) imposed the highest accelerations on the model with either the long or the short afterbody.
Date: February 9, 1949
Creator: Garrison, Charlie C.
Partner: UNT Libraries Government Documents Department

Investigation of a 1/5-scale model of a proposed high-submerged-speed submarine in the Langley full-scale tunnel

Description: Report presenting the results of an investigation to determine the drag, static stability, control effectiveness, boundary-layer conditions, and first-order effects of propeller operation on a scale model of a proposed high-submerged-speed submarine with various bridge-fairwater and tail configurations.
Date: October 31, 1950
Creator: Lipson, Stanley; Cocke, Bennie W. & Scallion, William I.
Partner: UNT Libraries Government Documents Department

Preliminary tank investigation of the use of single monoplane hydrofoils for high-speed airplanes

Description: Report presenting an investigation of the hydrodynamic take-off and landing characteristics of a model of a hypothetical jet- and rocket-propelled high-speed airplane fitted with various designs of a single monoplane hydrofoil mounted near the center of gravity. This testing is performed to determine the feasibility of the water-based operation of high-speed airplanes. Results regarding the general hydrodynamic characteristics, development of hydrofoils, and effects of some hydrofoil parameters are provided.
Date: March 22, 1949
Creator: King, Douglas A. & Rockett, John A.
Partner: UNT Libraries Government Documents Department

Landing characteristics in waves of three dynamic models of flying boats

Description: Powered models of three different flying boats were landed in oncoming waves of various heights and lengths. The effects of varying the trim at landing, the deceleration after landing, and the size of the waves were determined. Data are presented on the motions and accelerations obtained during landings in rough water.
Date: January 1952
Creator: Benson, James M.; Havens, Robert F. & Woodward, David R.
Partner: UNT Libraries Government Documents Department

Comparison of hydrodynamic-impact acceleration and response for systems with single and with multiple elastic modes

Description: Report presenting hydrodynamic impact testing made with a multimode elastic model consisting of a rigid prismatic float and a flexible wing and a comparison with similar experimental results for a single-mode system and with theoretical solutions. Testing was conducted in smooth water at two fixed trims and two flight-path angles over a range of velocities. Results regarding accelerations, time histories, oscillatory accelerations, elastic-body acceleration data, and rigid-body acceleration data are provided.
Date: February 1958
Creator: Miller, Robert W.
Partner: UNT Libraries Government Documents Department

Hydrodynamic impact loads in rough water for a prismatic float having an angle of dead rise of 30 degrees

Description: Report presenting an investigation in the impact basin to determine the hydrodynamic impact loads in rough water for a prismatic-float forebody with an angle of dead rise of 30 degrees. Testing occurred at fixed trim and each impact occurred into a 2-foot-high wave at 60, 45, or 30 feet in length. Results regarding the calculation of rough-water loads and comparison with smooth-water conditions are provided.
Date: December 1948
Creator: Miller, Robert W.
Partner: UNT Libraries Government Documents Department

Hydrodynamic impact loads in smooth water for a prismatic float having an angle of dead rise of 30 degrees

Description: Report presenting an investigation involving a prismatic-float forebody of 30 degrees angle of dead rise subjected to impacts in smooth water as part of a series of impact tests to investigate the effects of angle of dead rise on hydrodynamic loads of floats and hulls. Results indicated that the loads encountered during impacts can be predicted within the limits of experimental accuracy by curves and equations.
Date: June 1947
Creator: Miller, Robert W. & Leshnover, Samuel
Partner: UNT Libraries Government Documents Department

Water-landing investigation of a flat-bottom v-step model and comparison with a theory incorporating planing data

Description: Report presenting testing of a flat-bottom V-step model with a beam loading of 4.6 subjected to fixed-trim impacts in smooth water. Testing occurred at three different trim angles and a range of initial flight-path angles. Data were obtained as time histories of draft, vertical velocity, and vertical acceleration. The results are presented as plots of nondimensional lift, draft, vertical velocity, and time against flight-path angle at contact.
Date: May 1953
Creator: Miller, Robert W.
Partner: UNT Libraries Government Documents Department

Note on the calculation of boundary layers

Description: The properties of the solutions of the hydrodynamic equations of viscous fluid by "boundary-layer omission" are discussed. A method is indicated for the numerical determination of the solution for a known initial profile u(x(sub o),y) and pressure distribution p(x) within the region.
Date: November 1940
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department

On the theory of unsteady planing and the motion of a wing with vortex separation

Description: The disturbance imparted to water by a planing body give rise to a wave form of motion on the free surface, the length of the waves increasing indefinitely with increase in the Froude number and being directly proportional to the latter in the case of the plane or two-dimensional problem. At large Froude numbers the effect of the weight shows up to any appreciable extent only at some distance from the body, so that the flow near the body can be considered as part of a flow of an infinitely extending weightless fluid. This paper is a consideration of these characteristics as well as a formulation of the planing problem and its relation to the problem of a thin wing.
Date: May 1940
Creator: Sedov, L.
Partner: UNT Libraries Government Documents Department

Determination of rate, area, and distribution of impingement of waterdrops on various airfoils from trajectories obtained on the differential analyzer

Description: From Summary: "The trajectories of waterdrops in air flowing over airfoils are determined for three airfoil - angle-of-attack combinations using the differential analyzer to solve the differential equations of motion of the waterdrops. From these trajectories the rate of water impingement, the area of impingement, and the distribution of impingement are determined as functions of two dimensionless moduli. Comparisons are made of the rate of water impingement on these airfoils and the rate of water impingement on cylinders."
Date: February 16, 1949
Creator: Guibert, A. G.; Janssen, E. & Robbins, W. M.
Partner: UNT Libraries Government Documents Department

Bibliography and review of information relating to the hydrodynamics of seaplanes

Description: Report presenting a bibliography and review of information related to the hydrodynamics of seaplanes. Characteristics of conventional hulls and floats are discussed to show the effects upon performance of changes in design parameters like dead rise, depth of step, and angle of afterbody keel. Other topics include floats, lateral stabilizers, aerodynamic and propulsive considerations, unconventional configurations, hydrofoils, and piloting and handling.
Date: September 1945
Creator: Benson, James M. & Bidwell, Jerold M.
Partner: UNT Libraries Government Documents Department

Characteristics of a twin-float seaplane during take-off

Description: This report presents the results of an investigation of the planing and get-away characteristics of three representative types of seaplanes, namely, single float, boat, and twin float. The experiments carried out on the single float and boat types have been reported on previously. This report covers the investigation conducted on the twin-float seaplane, the DT-2, and includes as an appendix, a brief summary of the results obtained on all three tests. At low-water speeds, 20 to 30 miles per hour, the seaplane trims by the stern and has a high resistance. Above these speeds the longitudinal control becomes increasingly effective until, with corresponding speeds of 56 to 46 miles per hour. It was further determined that an increase in the load caused little if any change in the water speed at which the maximum angle and resistance occurred, but that it did produce an increase in the maximum angle.
Date: January 1927
Creator: Crowley, John W., Jr. & Ronan, K. M.
Partner: UNT Libraries Government Documents Department

Characteristics of a single float seaplane during take-off

Description: At the request of the Bureau of Aeronautics, Navy Department, the National Advisory Committee for Aeronautics at Langley Field is investigating the get-away characteristics of an N-9H, a DT-2, and an F-5l, as representing, respectively, a single float, a double float, and a boat type of seaplane. This report covers the investigation conducted on the N-9H. The results show that a single float seaplane trims aft in taking off. Until a planing condition is reached the angle of attack is about 15 degrees and is only slightly affected by controls. When planing it seeks a lower angle, but is controllable through a widening range, until at the take-off it is possible to obtain angles of 8 degrees to 15 degrees with corresponding speeds of 53 to 41 M. P. H. or about 40 per cent of the speed range. The point of greatest resistance occurs at about the highest angle of a pontoon planing angle of 9 1/2 degrees and at a water speed of 24 M. P. H.
Date: January 1925
Creator: Crowley, J. W., Jr. & Ronan, K. M.
Partner: UNT Libraries Government Documents Department