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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

Effects of Variations in Forebody and Afterbody Dead Rise on the Resistance and Spray Characteristics of the 22ADR Class VPB Airplane: Langley Tank Model 207, TED No. NACA 2361

Description: From Summary: "An investigation was made to determine the effects of changes in the amount and distribution of forebody and afterbody dead rise on the hydrodynamic resistance and spray characteristics of a 1/11-size model of the Bureau of Aeronautics design No. 22ADR class VPB airplane. The variations in dead rise within the range investigated had no significant effects on resistance or trim, free to trim, or on resistance or trimming moment, fixed in trim. The coordinates of the peaks of the bow-spray blisters, with reference to the model, were measured at low speeds, and it was found that the model with the low dead rise at the bow had the lowest blisters."
Date: August 28, 1947
Creator: Clement, Eugene P. & Daniels, Charles J.
Partner: UNT Libraries Government Documents Department

Tank investigation of a powered dynamic model of a large long-range flying boat - Langley tank model 180

Description: Report presenting an investigation of the principles for designing the optimum hull for a large long-range flying boat to meet the requirements of seaworthiness, minimum drag, and ability to take off and land at all operational gross loads. The aerodynamic and hydrodynamic qualities of the model were investigated in Langley tank no. 1.
Date: March 1947
Creator: Parkinson, John B.; Olson, Roland E. & Haar, Marvin I.
Partner: UNT Libraries Government Documents Department

Tank tests of a 1/10-size model of a hypothetical flying boat with a hull length-beam ratio of 9.0

Description: Report presenting an investigation of the hydrodynamic characteristics of a powered dynamic model of a hypothetical flying boat with a hull length-beam ratio of 9.0 in Langley tank no. 1. Results regarding trim limits of stability, center-of-gravity limits for stable take-off, landing stability, resistance, and spray characteristics are provided.
Date: July 1948
Creator: Haar, Marvin I.
Partner: UNT Libraries Government Documents Department

Tests of the landing on water of a model of a high-speed airplane - Langley tank model 229

Description: Report presenting an investigation at the tank no. 2 monorail of the landing on smooth water of a dynamic model of a hypothetical jet- and rocket-propelled airplane designed to fly at transonic speeds. The model skipped out of the water and experienced maximum normal accelerations up to 7.4g and maximum longitudinal accelerations up to 4.5g. Results of landing the basic model and landing the modified model that has a slightly different fuselage are provided.
Date: December 9, 1947
Creator: King, Douglas A.
Partner: UNT Libraries Government Documents Department

Tank tests of three types of afterbodies on a flying-boat model with basic hull length-beam ratio of 10.0

Description: Report presenting testing of three different types of afterbodies on a powerful dynamic model of a flying boat with a basic length-beam ratio of 10.0. The three afterbodies tested were one with constant dead rise, one with warped dead rise, and one of extended length with warped dead rise. Results regarding aerodynamic characteristics and hydrodynamic characteristics are provided.
Date: March 1948
Creator: Garrison, Charlie C. & Clement, Eugene P.
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

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

Tank Tests of 1/5.5-Scale Forward Dynamic Model of the Columbia XJL-1 Amphibian - Langley Tank Model 208, TED No. NACA 2336

Description: Tests of a powered dynamic model of the Columbia XJL-1 amphibian were made in Langley tank no.1 to determine the hydrodynamic stability and spray characteristics of the basic hull and to investigate the effects of modifications on these characteristics. Modifications to the forebody chime flare, the step, and the afterbody, and an increase in the angle of incidence of the wing were included in the test program. The seaworthiness and spray characteristics were studied from simulated taxi runs in smooth and rough water. The trim limits of stability, the range of stable positions of the enter of gravity for take-off, and the landing stability were determined in smooth water. The aerodynamic lift, pitching moment, and thrust were determined at speeds up to take-off speed.
Date: February 17, 1947
Creator: Havens, Robert F.
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

Hydrodynamic qualities of a hypothetical flying boat with a low-drag hull having a length-beam ratio of 15

Description: Report presenting an investigation of the hydrodynamic qualities of a hypothetical flying boat with a hull with a length-beam ratio of 15 in tank no. 1. The flying boat had a design gross weight of 75,000 pounds, a gross load coefficient of 5.88, 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 longitudinal stability, spray characteristics, take-off performance, and summary chart are provided.
Date: April 1948
Creator: Carter, Arthur W. & Haar, Marvin I.
Partner: UNT Libraries Government Documents Department

Hydrodynamic and aerodynamic tests of models of floats for single-float seaplanes NACA models 41-D, 41-E, 61-A, 73, and 73-A

Description: Tests were made in the NACA tank and in the NACA 7 by 10 foot wind tunnel on two models of transverse step floats and three models of pointed step floats considered to be suitable for use with single float seaplanes. The object of the program was the reduction of water resistance and spray of single float seaplanes without reducing the angle of dead rise believed to be necessary for the satisfactory absorption of the shock loads. The results indicated that all the models have less resistance and spray than the model of the Mark V float and that the pointed step floats are somewhat superior to the transverse step floats in these respects. Models 41-D, 61-A, and 73 were tested by the general method over a wide range of loads and speeds. The results are presented in the form of curves and charts for use in design calculations.
Date: July 1938
Creator: Parkinson, J. B. & House, R. O.
Partner: UNT Libraries Government Documents Department

Hydrodynamic-stability tests of a model of a flying boat and of a planing surface having a small downward projection (hook) on the planing bottom near the step

Description: Report presenting stability testing of two dynamic models in tank no. 1 in order to investigate the effects of adding a small projection, or hook, on the planing bottom of the forebody near the step of a seaplane. Tests with two different projections had a rather large effect on all of the trim limits and the landing stability.
Date: January 1943
Creator: Benson, James 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

Piloting of flying boats with special reference to porpoising and skipping

Description: From Summary: "The various types of hydrodynamic instability - including porpoising, skipping, and yawing - that may be encountered during take-off or landing of a flying boat are described and the piloting technique required for efficient take-offs and landings is discussed. Suggestions are made for assisting a pilot to become familiar with the take-off and landing qualities of a flying boat that is new to him."
Date: February 1944
Creator: Benson, James M.
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

Applications of Modern Hydrodynamics to Aeronautics

Description: The report gives, rather briefly, in part one an introduction to hydrodynamics which is designed to give those who have not yet been actively concerned with this science such a grasp of the theoretical underlying principles that they can follow the subsequent developments. In part two there follows a separate discussion of the different questions to be considered, in which the theory of aerofoils claims the greatest portion of the space. The last part is devoted to the application of the aerofoil theory to screw propellers. A table giving the most important quantities is at the end of the report. A short reference list of the literature on the subject and also a table of contents are added.
Date: 1923
Creator: Prandtl, L.
Partner: UNT Libraries Government Documents Department

The Resistance to the Steady Motion of Small Spheres in Fluids

Description: "There seems to be little reliable information conveniently available as to the resistance encountered by small spheres moving steadily at moderate speeds in fluids. The present paper, while presenting nothing new in the way of either theory or data, has three objects: first to show that published data are sufficient to furnish approximate information; second to present this information in form convenient for computation; and, third to indicate where further research is needed" (p. 1).
Date: February 1926
Creator: Castleman, R. A.
Partner: UNT Libraries Government Documents Department

Effect of Increase in Afterbody Length on the Hydrodynamic Qualities of a Flying-Boat Hull of High Length-Beam Ratio

Description: Report presenting an investigation to determine the effects of increased afterbody length on the hydrodynamic qualities of a model of a flying boat with a hull with a length-beam ratio of 15. Results regarding longitudinal stability, spray characteristics, excess thrust for take-off, landings in waves, and a summary chart are provided.
Date: April 1949
Creator: Kapryan, Walter J. & Clement, Eugene P.
Partner: UNT Libraries Government Documents Department

Water-Impact Theory for Aircraft Equipped With Nontrimming Hydro-Skis Mounted on Shock Struts

Description: Note presenting theoretical equations derived for the motion of aircraft equipped with hydro-skis mounted on shock struts during take-off and landing operations on a water surface. Two hydrodynamic force relations, one more accurate but more complex than the other, are considered.
Date: September 1958
Creator: Schnitzer, Emanuel
Partner: UNT Libraries Government Documents Department

Hydrodynamic Impact Loads in Smooth Water for a Prismatic Float Having an Angle of Dead Rise of 10 Degrees

Description: Note presenting a prismatic float with an angle of dead rise of 10 degrees, which was subjected to smooth-water impacts in the impact basin. The investigation consisted of a series of impacts at fixed angles of trim of 3 degrees, 12 degrees, 20 degrees, and 30 degrees and at flight-path angles from 2 to 23 degrees. Results regarding the effect of dead-rise function and aspect-ratio factor on hydrodynamic load and chine immersion are provided.
Date: January 1956
Creator: Edge, Philip M., Jr.
Partner: UNT Libraries Government Documents Department

Hydrodynamic Pressure Distribution Obtained With a Streamline Body Equipped With Chine Strips

Description: Memorandum presenting an investigation to determine the nature of the pressure distribution and the order of magnitude of the pressures on a streamline body moving on a water surface. The body of revolution was equipped with chine strips and had a fineness ratio of 9. The results from the investigation indicate that there is a characteristic pattern of hydrodynamic pressure distribution for streamline bodies equipped with chine strips and moving on a water surface.
Date: September 1, 1955
Creator: Weinflash, Bernard
Partner: UNT Libraries Government Documents Department