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In reality, the principle of similitude is not applicable to the hulls, the designing of which increases in difficulty with increasing size of the seaplanes. In order to formulate, at least in a general way, the basic principles of calculation, we must first summarize the essential characteristics of a hull with reference to its gradual enlargement. In this study, we will disregard hulls with wing stubs, as being inapplicable to large seaplanes.
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.
An analysis of available theory on seaplane impact and a proposed modification thereto are presented. In previous methods the overall momentum of the float and virtual mass has been assumed to remain constant during the impact but the present analysis shows that this assumption is rigorously correct only when the resultant velocity of the float is normal to the keel. The proposed modification chiefly involves consideration of the fact that forward velocity of the seaplane float causes momentum to be passed into the hydrodynamic downwash (an action that is the entire consideration in the case of the planing float) and consideration of the fact that, for an impact with trim, the rate of penetration is determined not only by the velocity component normal to the keel but also by the velocity component parallel to the keel, which tends to reduce the penetration. Experimental data for planing, oblique impact, and vertical drop are used to show that the accuracy of the proposed theory is good.
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.
This report gives the results of wind-tunnel tests with a seaplane model as a contribution to the solution of the aerodynamic problems. In the tests it was assumed that the seaplane rested motionless on the water and was exposed, in various positions with respect to the supposedly flat surface of the water, to a uniform air current 0 to 360 degrees.
The present investigation is an endeavor to express the jolting stresses, designated as landing impacts, undergone by seaplanes in landing and taking off from rough water, as functions of specific factors, in order to enable the evaluation of empirically obtained results and thus acquire theoretical data for the construction of seaplane floats and hulls.
During the course of an aerodynamic loads investigation of a model of the Martin XP6M-1 flying boat in the.Langley 16-foot transonic tunnel, longitudinal-aerodynamic-performance information was obtained. Data were obtained at speeds up to and exceeding those anticipated for the seaplane in level flight and included the Mach number range from 0.84. to 1.09. The angle of attack was varied from -2deg to 6deg and the average Reynolds number, based on wing mean aerodyn&ic chord, was about 3.7 x 10(exp 6). This seaplane, although not designed to maintain level flight at Mach numbers beyond the force break, was found to have a transonic drag-rise coefficient of 0.0728, with an accompanying drag-rise Mach number of about 0.85. A large portion of the.drag rise and the relatively low value of drag-rise Mach number result from the axial coincidence of the maximum areas of the principal airplane components.
The Sprat is similar the Blackburn Swift and Dart models but is designed as a trainer. It is powered with a smaller 275 HP Rolls-Royce Falcon engine. It is a 2 seat biplane with equal sized upper and lower wings. It can quickly convert from a land to a seaplane.
This is a multi-engine monoplane with a central hull and without external bracing. The trim of the seaplane on the water is assured by two wing floats, one on each side of the hull 9 m. from its axis. It has a total power of 2100 HP. from 5 air cooled Jupiter radial engines.
It's fuselage is made entirely of wood. It has 6 gasoline tanks each with a capacity of 255 liters. It is a single engine biplane with wings mounted above the body of the seaplane.
This report covers the following aspects of large seaplane design and construction: heavy wing loading; propeller design; how the motion of the airplane is affected by increasing the dihedral angle; power plants; floats; and the hull.
Effect of gross load and bow modifications on hydrodynamic characteristics of subsonic mine- laying seaplane
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.
Societe Provencale de Constructions Aeronautiques, builder of the "Meteore 63" has constructed a three engine (biplane) seaplane which has met conditions for a seaworthy certificate of the first class.
The Calcutta is a large seaplane, with seating for 16 and a payload of 3,400 pounds.
This part of the report presents characteristics and graphic representations of water resistance. The laws of similarity are discussed as well as the theory of model tests. The test procedures and model tests of other countries are also discussed.
Different float designs are presented and the investigations are discussed.
History of early seaplanes and associated hydrodynamics