US2281471A - Loading raft - Google Patents

Description

April 28, 1942. F. J. BAUM ETAL LOADING RAFT Filed Jan. 4, 1941 INVENTORST ATTORNEYS.

m u W v 0W M0 Z Patented Apr. 28, 1942 LOADHNG RAFT Fred J. Baum, Glendale, and Eldon M. Wilson, Hermosa. Beach, Calif, assignors to Northrop Aircraft, Ina, Hawthorne,

of California Calif., a corporation Application January 4, 1941, Serial No. 373,076 3 Claims. v((31. 214-13) This invention relates to loading rafts for seaplanes, and particularly to equipment for loading the bomb racks of naval bombing planes.

Seaplane bombers of the type particularly contemplated by this invention carry their bombs in racks beneath the body of the plane. Each bomb is supported from a pair of spaced lugs which are engaged by a bomb release mechanism. Such bombs may be of any weight from say, fifty pounds, to a ton or more, and the planes which carry them are correspondingly large and heavy. There are obvious disadvantages to beaching such a plane, loading its racks on shore, and launching it again with the racks loaded, but there are even greater obvious disadvantages to floating a raft or loading barge beneath a seaplane, and with both raft and plane rocking at different periods, as will occur even with very slight disturbance of the water upon which the plane is floating, to attempt to engage the two half-inch square lugs on a 2,000 pound bomb with the retaining hooks upon the plane. I

The object of the present invention is to avoid the disadvantages inherent in either of these two procedures. Pursuant to this primary object, the objects of this invention are: To provide a loading raft which may be floated into position beneath a seaplane, and which, when so floated, can be accurately positioned laterally of the plane and locked in such position; to provide a loading raft which, when so locked, will move with the plane in any sea in which loading can be attempted at all; to provide means whereby engagement and disengagement between the loading raftand the seaplane may readily be accomplished; to provide a raft having means for raising the bombs Vertically into engagement with the bomb racks and, with the bombs so raised, for moving them'longitudinally of the plane to bring the carrying lugs on the bomb into accurate engagement with their "carriers on the racks; to provide a raft which may be beached for loading without interference with or damage to the plane engagement means on the raft; and to provide a device of the character described wherein the plane engaging means, hoist mechanism, and self-propulsive mechanism for the raft may all beaccomplished from a single, simple and inexpensive prime mover.

Other objects of the invention will be apparent or will be specifically pointed out in'the description forming a part of this specification, but the invention is not limited to'the embodiof a loading raft embodying this invention.

Fig. 2 is an end elevation of the raft, illustrating the method of positioning and locking it beneath a seaplane, which latter is indicated by dotted lines.

Fig. 3 is a fragmentary sectional view on a somewhat larger scale than the other figures, the plane of section being indicated by the line 3-3 of Fig. 1.

Considered broadly the invention comprises a buoyant hull adapted to float between the pontoons of a seaplane as it rests upon the water. Mounted on each end of the hull are cradles shaped to flt beneath the pontoons, these cradles being movably mounted so that they can be raised to bear a portion, at least, of the weight of the plane, thus raising the plane, depressing the hull, and locking the two together so that they move as a single unit, and so that the position of the raft laterally of the plane is definitely fixed by the engagement of the cradles with the pontoons. A plurality of hoists are preferably mounted longitudinally of the raft, and spaced in longitudinal alinement with the bomb racks of the'plane. Each of these hoists comprises a pair of lever arms, pivoted on axes transverse to the raft, so that they may be raised to a position approaching the vertical or lowered in opposite directions to a position more nearly approaching the horizontal. The upper ends of these levers carry rollers working in slots in a horizontal carrier or table, the slots being so positioned that the rollers seat in the outer ends of the slots when the levers are in lowered position. Means, preferably pneumatic, are provided for raising the arms, to bring abomb resting upon the carrier up to the level of the bomb racks, in whichposition the table can be slid along the rollers to place the carrying lugs on the bombs accurately into position for engagement by the'bomb carriers. The cradle operating means are also preferably pneumatic, and it is therefore'possible to use a single small motor, such as a gasoline engine, to drive a compressor for operating both cradles and hoists, and also to drive a propeller so that the raft can be maneuvered into position beneath the plane under its own power.

The drawings show a pref-erred embodiment of the invention, comprising a buoyant hull I, which is preferably a simple boXli-ke barge or scow carrying a pair of longitudinal keels 2 which also serve as skids when the raft is beached. A small gasoline motor 3 is preferably provided, which is geared to a propeller 4, and which also serves to drive a compressor 5, although a hydraulic pump may be substituted for the compressor if desired. Pneumatic operation, however, gives greater speed of operation and flexibility to the equipment to be operated thereby. A rudder l, operated by a simple tiller 9 is also preferably provided for steering the raft into position beneath a seaplane.

Fig. 2 shows the raft thus positioned beneath a plane l0, whose general outline is indicated by the dotted lines, and which floats on the conventional pontoons ll.

Mounted on each end of the raft are the cradles for engaging these pontoons. Each cradle comprises a substantial lever arm l2, pivoted on a short stub shaft l3 on the end of the boxlike hull. The lower or outer end of the arm l2 carries the cradle proper, comprising a structural T-section M, shaped as a shallow V, the end of one arm of which is welded or otherwise secured to the end of the lever [2. The angle of the V is adapted to conform to the lower surface of the pontoons II, and the upper surface of the V is lined with rubber or other soft material 15 to prevent damage to the pontoon when it becomes into engagement therewith.

The upper end of each of the arms 12 is pivotally connected by a clevis or yoke I! with a piston rod I9 working in a pneumatic cylinder 20, and the cylinders, in turn, are pivoted on studs Zl to the end of the hull near the median line thereof. When the cylinders are exhausted the cradles take the position shown in the full line in Fig. 2; when air is admitted to their outer ends, they raise the cradles beneath the pontoon to the position shown in the broken line of the same figure.

The displacement of the raft is so computed that its normal water line, fully loaded, is below that shown in the figure. Therefore, when the cradles are raised, they carry a portion of the weight of the plane, raising it slightly and depressing the raft, so that its buoyancy locks plane and raft together while the plane is being loaded. Conversely, of course, after the loading operation is complete, the cylinders are exhausted and the raft rises and the plane sinks to the normal water levels. Rubber buffers or sponsons 22 are also provided, running longitudinally of the raft, to prevent damage to the pontoon when raft and plane are floating separately with the cradles disengaged.

A plurality of bomb loading tables or hoists are also preferably provided, mounted longitudinally upon the raft and with the spacing of their center lines corresponding accurately to the spacing of the bomb racks on the plane. This is possible, of course, because when the cradles are engaged the lateral position of the raft with respect to the plane is accurately determined by the nesting of the pontoons within the V- shaped cradles.

Each hoist comprises two sets of levers 25, of the bell crank type, which are mounted on transverse axes 2T. Pivoted to the shorter end of these levers are piston rods 29, working in pneumatic cylinders 30, these cylinders alsov being pivoted on transverse axes 3|. When the cylinders are exhausted and the pistons extended, the long arms of the bell cranks 25 lie nearly flat,

pointed in opposite directions, but when the piston rods are retracted these lever arms rise to a position approaching the vertical.

The upper ends of the levers carry rollers 32 running in slots 33 formed in the side members of the bomb tables or cradles 34. When the pistons are extended the rollers seat practically in the end of the slot 33, preventing any material longitudinal motion of the tables. The tops of the tables are of shallow V-shaped section, so that a bomb may be placed thereon without danger of its rolling, and with its carrying lugs accurately alined on its upper side. Air is admitted into the two cylinders at the opposite ends of the hoist simultaneously but controlled by separate valves so that proper height of each attaching lug may be attained, raising it to the position shown by the broken lines in Figs. 1 and 2, and the slots 33 are made of suflicient length so that the tables can then be rolled longitudinally of the raft to aline the lugs with the lug-engaging elements of the bomb racks and can then be locked by hand set screws 32' (as shown, in Fig. 3) to prevent further movement longitudinally. Since the raft is already carrying a portion of the weight of the plane, the transfer of the weight of the bomb between the hoist and the rack makes no difference in trim.

After the rack has engaged the bomb the hoist is dropped back into the position shown by the solid lines in the two figures, and the operation is repeated with the next bomb. By the use of the pneumatic cylinders, the bomb can be raised very rapidly to the point just beneath the rack, the lugs can be alined, and then a slight additional lift will seat the lugs in the racks. Furthermore, since the carrying lugs are made with standard size and spacing for various sizes of bombs, and since the hoists are under full control at all times, it is possible to use the same equipment for loading small bombs, as indicated by the reference characters 35 or large bombs as shown by 36.

With the rack loaded, and the hoist lowered, the cylinders 20 are permitted to exhaust, dropping the cradles and permitting the withdrawal of the raft. Normal procedure is then again to raise the cradles and beach the raft for receiving its next load. Handles 39 are provided at each end of the raft to facilitate the beaching, and since the keels 2 extend below the raised cradles no harm comes to the latter in this operation.

What I claimed is as follows:

1. In a bomb loading rack wherein a buoyant hull carrying bombs is shaped to float between pontoons of a seaplane having bomb racks thereon, the improvement comprising a pair of arms pivotally mounted at each end of said hull, a cradle fastened to the end of each arm and shaped to fit under the lower surface of a pontoon, said cradle having lateral portions extending above the lowest portion of said pontoon on each side of said lowest portion, and means for moving said arms to engage said cradles with said pontoons to raise said pontoons and depress said hull inposition to load said bombs into said seaplane, said cradles and said arms forming the sole vertical and lateral positioning and locking link between said hull and said pontoons, a bomb carrying table in said hull and means for raising said table to register bombs thereon with the racks on said seaplanes.

2. A loading raft in accordance with claim 1 including a pair of keels on said hull, said keels being deeper than said cradles when in raised position and adapted to act as skids when beaching said raft.

3. In a bomb loading rack wherein a buoyant hull carrying bombs is shaped to float between pontoons of a seaplane having bomb racks thereon, the improvement comprising a pair of arms pivotally mounted at each end of said hull, a cradle fastened to the end of each arm and shaped to fit under the lower surface of a pontoon, said cradle having lateral portions extending above the lowest portion of said pontoon on each side of said lowest portion, and means for moving said arms to engage said cradles with said pontoons to raise said pontoons and depress said hull in position to load said bombs into said seaplane, said cradles and said arms forming the sole vertical and lateral positioning and locking link between said hull and said pontoons, a, plurality of hoists disposed on said hull in alinement with the bomb racks on said seaplane when said hull and said seaplane are thus locked, levers mounted on axes transverse to said hull, means for simultaneously moving said levers in opposite directions from positions approaching the horizontal to positions approaching the vertical, and means on said levers for engaging slots formed longitudinally of said bomb table, said slots being of sutficient length and so disposed that said engaging means are positioned substantially at the ends of said slots when said levers are lowered and in intermediate portions thereof when said levers are raised whereby said table is movable longitudinally on said engaging means when in raised position.

FRED J. BAUM.

ELDON M. WILSON.

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