US2349584A - Flying boat hull - Google Patents

Description

y 1944- K. ARNSTEIN ETAL 2,349,584

FLYING BOAT HULL Filed Aug. 24, 1940 3 Sheets-Sheet l y 1944. K. ARNSTEIN ET AL 2,349,584

. FLYING BOAT HULL Filed Aug. 24, 1940 a Sheets-Sheet 2 ZhWc Mwb Karl flf/zste in 1% May 23, 1944. ARNSTEIN ETAL 2,349,584

FLYING BOAT HULL Filed Aug. 24, 1940 s Sheets-Sheet 5 Patented May 23, 1944 UNITED STATES PATENT orrics FLYING BQAT HULL Karl Arnstein, Akron,

and Benjamin J. Schnitzer,

Stow, Ohio, assignors to Wingioot Corporation,

Akron, Ohio, a

corporation of Delaware Application August 24, 1940, Serial No. 354,056 a v 11 Claims.

. structure against injurious impact forces in the water. I

It has been customary to build the hulls of flying boats entirely rigid of materials such as either metal or wood. The landing shocks to which such boats are subjected are occasionally extremely severe and, therefore, the hull, as well as the remaining structure, including the wings, must be made correspondingly strong and heavy. However, even then hull injuries frequently occur. It is known that successful use of pneumatic floats, constructed of flexible material, has been made for hydroplanes. It is also-knwn that designs exist'which suggest a flying boat hull constructed entirely or partially as an inflatable hollow body which is stiffened by pressure from the inside. Such designs, however, have not been proven practicable for various reasons.

This invention overcomes the above-mentioned deficiency by employing a rather conventional hull construction in combination with a resilient landing cushion which is attached underneath the bottom of' the rigid hull structure. By this method not only the landing shocks are dampened, but it also quickens a take-off of the. flying boat, due to the adaptability of the soft cushion to bring about a smoother flow of the water. Such an arrangement of the shock-absorbing portion of the hull has the advantage that full use can be made of the space within the hull structure for operation, storage, etc. purposes without any interference by the shock absorber. The size and construction of the landing cushion may be varied to a great extent, according to requirements.

The bottom of the hull is usually provided with a. step to avoid suction while getting oil the water. With a hull being provided with a cushnumerable little gas cells entirely separated from each other by very thin rubber walls. The advantage of employing a cushion underneath a flying boat hull does not lie only in the protection of th structural parts against hard impacts, but also in the fact thatthe entire boat structure .can be carried out lighter in weight,

ion the step can be easily formed by a cushion which covers onlythe front portion of. the hull bottom to be immersed, or a cushion may be employed containing the step and extending over the full length of that hull portion. The width of the cushion may correspond to that of the bottom of the hull or may extend over only a portion of it. 1

So far as the construction of the landing cushion, according to this invention, is concerned,

it can be of the inflatable pneumatic type or the air inflatable space can be displaced by light-weight rubber foam which consists of inthis resulting in greaterefficiency and better performance of the aircraft. In using the pneu' matic-type cushion, the step whichis of advantage for an easier take-off, may be made to disappear partly or entirely by releasing some of the air in the cushion poriton in front of the step when out of the water, thus reducing the airre-- sistance of the boat in flight.

For a better understanding of this invention, reference is now made to the accompanying drawings wherein several embodiments are shown merely by-way of illustration, and where Fig. 1 is a side view of one form of flying boat embodying the invention;

Fig. 2 is a bottom view of Fig. 1;

Fig. 3 a front view thereof;

Fig. 4 is a cross-sectional view on an enlarged scale taken on line 4-4 of Fig. 1;

Fig. 5 is one modification of the construction shown in Fig. 4;

Figs. 6, 7 and 8 are views similar to Figs. 1, 2 and 3, respectively, showing another modification of the invention;

Fig. 9 -is a fragmentary longitudinal sectional View, in enlarged scale, showing the step portion of the landing cushion;

Fig. 10 is a cross-section,' in enlarged scale, along the line Ill-l0 of F156;

Fig. 11 is a modification of the construction shown in Fig. 10;

Figs. 12 and 13 are further modifications of the construction shown in Fig. 10; and

Fig. 14 is a modification of the constructions shown in Figs. 4 and 5.

In the drawings the same numerals are used for identifying corresponding parts throughout the different views.

Referring first to Figs. 1 to 4 inclusive, it will be seen that the flying boat therein shown has a rigid hull II which is provided at its front portion underneath the bottom with a landing cushion l2, including a number of flexible air tubes l3 of substantially equal diameter. These tubes, which are arranged longitudinally and substantially parallel to each other, are enclosed by a cover M which is fastened along its edges l5 by a metal strip l6 and bolts I! to the rigid hull, and are-cemented to the cover by fabric angle strips I8 to prevent dislocation. Some or all of these tubes may be provided with bolts l9 securely embedded with their heads in the tube walls and to be fastened to the bottom'of the hull. Chafing injuries during service.

, to accomplish an easy take-off from the water. The material used for the tubes, as well as for the cover, is water-proof and is preferably rubberized fabric composed of one or more plies, depending on the service it has to perform. Each one of the tubes I3 is equipped with an'air inflation valve 23. The valves of symmetrically located tubes are connected in pairs by hose 24, from each of which leads a line attached to an air manifold 26 which is provided with a stop it valve 21 for each line 24. A main line 28 feeds the air from a tank 2!! to the manifold 26. Although the operating pressure in the tubes is relatively low, each pair of tubes is also equipped with a safety valve 30, set to blow off at a prede- 20 termined pressure. This pressure might be exceeded when the, flying boat reaches high altitudes, whereby the pressure difference. between inside the tubes and the outside atmosphere considerably increases. There also is provided a 2:! pressure gauge 3| connected to a manifold 32 into which a line 33 leads from each pair of air cover under sufiicient tension for keeping the tubes in the corrugations. Otherwise, the con- 0 struction is substantially the same as that described in reference to Fig.4.

Another modification of the above-described construction of the landing cushion is shown in Figs. 6 to 10. The cushion in this construction extends over the full length'of the hull bottom, that is, so far as it immerses in the water, and

is of considerably greater height, thus securing a softer impact and a better protection of the rigid hull structure. The bottom of the hull H is shown straight in the cross-section and the keellike. shape is produced entirely by the landing cushion 4|, which also contains the step 42. The air tubes l3, arranged again substantially parallel to each other, are of. different diameter decreasing from the center outwardly. Each tube is fastened by bolts I9 to the bottom of the hull to be held in place. The cover I4, which is fastened by metal strips l6 and bolts I! along its edges Hi to the rigid hull, encloses the air tubes of which those of the front portion of the cushion are of larger diameter than those of the rear portion. A transverse wall 43 is inserted between the front and rear tubes for the purpose ofshaping the step. Chafing strips or moldings 20 and 2|, preferably made of rubber, for protecting the cushion are also provided, and the cover I4 is .attached by fabric angle strips l8 to the air tubes.

In case the disappearance ofthe step is desired during flight, the outer cover portion 42 is made of resilient material which, when some of the air in the front tubes is released, will contract and smooth out somewhat, or substantially eliminate the step as shown in dotted lines, and thus reduce the air resistance during flight. In doing that,

some of the air is released from the front tubes; the inside pressur may even be reduced below that of the atmosphere.

This very same construction is shown, somewhat modified, in Fig. 11. Here, each air tube has on top a longitudinal indentation of triangular cross-section into which fits a girder fastened to and supporting the tube. This way, the tubes are held much firmer at the base against yielding laterally. With this arrangement there is also the possibility of avoiding use of the outer bottom cover of the rigid hull structure, except, perhaps of a small width 46 which braces the outer wall of the hull against the adjacent triangular girder. I

Figures 12, 13 and 14 show modifications of the cushion construction of Fig. 10. In these views the landing cushion consists of two enclosing walls 48 and 49, as well as of partition walls 50, cemented by angle strips 5| to the enclosing walls and thus divide the cushion into a number of separate air chambers, all of which are inflated with compressed air. In Fig. 12, the partition walls are arranged in zig-zag fashion giving the air chambers a triangular cross-section, whereas in Fig. 13 the partition walls are more or less parallel to each other and form, together with the outer walls, air chambers of substantially height. This construction may be found most effective, particularly in cases where a relatively short type landing cushion is used.

The above-detailed description of this invention, it is believed, will give a clear conception of the advantage of the new features incorporated therein over previous constructions. However, it should be understood that the examples illustrated and described do by no means exhaust the possibilities of the invention, but that many other combinations and variations therefrom might be included which fall within the, spirit and scope of this invention, as defined by the attached claims.

We claim: I

1. In combination in a flying boat, a rigid hull structure, a resilient landing cushion underneath and fastened to said rigid hull, said landing cushion comprising a plurality of longitudinal flexible inflatable tubes substantially parallel to each other, a step dividing said landing cushion into a front portion and a rear portion, the inflatable tubes in said front'portion as well as in said rear portion decreasing in diameters from the longi- 5 tudinal center toward the sides of the hull, the

tubes in the front portion being larger in diameter than corresponding tubes in the rear portion, fastening means for attachingsaid tubes to the bottom of said rigid hull, an airtight and waterproof flexible cover enclosing said tubes being attached and sealed to th bottom of said rigid hull, means for attaching said cover to the bottoms of said tubes, and chafing strips longitudinal of and fixed to the outer surface of said cover for protection.

2. In combination in a flying boat, a rigid hull structure having a longitudinally upwardly curved bottom, front and rear, a resilient landing cushion attached to the bottom of said hull, said cushion comprising two groups of air containers, 8. front group and a rear group, composed of flexible but non-stretchable air-tight and waterproof fabric, andadapted to be inflated with air usually at super-atmospheric pressure, the front group being of greater height than th rear group adjacent thereto, each of said groups being enclosed by an air-tight flexible cover, which is fastened and sealed along the bottom of said rigid hull, and 'a resilient air-tight connection'forming a step between said front and rear covers, which, when the air pressure in said front containers is reduced during flight, will contract and thus reduce the height of the step between the two groups of con-' tainers and, correspondingly, the air resistance of said step.

3. In combination in a flying boat, a rigid hull structure having longitudinally an upwardly curved bottom, front and rear, a resilient inflatable landing cushion fltted and attached to said bottom, the front portion of said cushion being of greater length and of greater height than its rear portion, thus forming a step between the two portions, the width of the front portion of said cush-' ion being substantially the same as that of the bottom of the rigid hull and the width of the rear portion diminishing rearwardly from said step to give streamline eflect.

4. In combination in a flying boat, a rigid hull structure, an air-inflatable landing cushion mounted below said rigid hull and consisting of an upper flexible wall and of a lower flexible wall spaced from each other, said upper wall resting against the bottom of the rigid hull, longitudinally disposed flexible partitions spaced from each other and connecting said walls to divide the landing cushion in a plurality of individual air-tight to provide a stable lateral support for said tubes,

- and an outer flexible cover having its edges secured compartments, said compartments decreasing in I cross-sectional height from the longitudinal center toward the sides of the hull and valves inserted in the enclosing wall for inflating said compartments with air.

5. In combination in a flying boat, a rigid hull structure, an inflatable landing cushion mounted underneath said rigid hull and consisting of an upper flexible wall and of a lower flexible'wall, both combining to form an air-tight bag, said upper wall resting against the bottom of said rigid structure, longitudinal flexible partitions arranged transversely inzig-zag fashion and being connected to said upper and said lower wall to divide the landing cushion in a plurality of individual air-tight compartments, said compartments decreasing in cross-sectional height from the longitudinal center toward the sides of the hull and valves inserted in the enclosing wall for inflating said compartments with air.

6. In a flying boat, the combination of a hull of rigid construction and a resilient landing cushion underneath the bottom of said hull, said cushion comprising a plurality of separate inflatable air tubes, each of which has on top a longitudinal indentation, a corresponding number of girders fltting into said indentations and secured to the bottom of said hull toprovide stable lateral support for said tubes, and an outer flexible cover having its edges securedto said rigid hull and providing a smooth air-tight enclosure of said air tubes.

7. In a flying boat, the combination of a hull of rigid construction and a resilient landing cushion underneath the bottom of said hull, said cushion comprising a plurality of separately inflatable air tubes arranged longitudinally, said tubes decreasing in diameters from the longitudinal center toward the sides of the hull, and each of the tubes having on top a longitudinal indentation, a corresponding number of girders fitting into said indentations and secured to the bottom of said hull to said rigid hull and providin a smooth, airtight enclosure of said air tubes.

8. In a flying boat, the combination of a hull of rigid construction and a resilient landing cushion underneath the bottom of said hull', said cushion comprising a plurality of longitudinal separately inflatable air tubes substantially parallel to each other, a step dividing the landing cushion into a front portion and a rear portion, the tubes in the front portion being larger in diameter than corresponding tubes in the rear portion and each having on top a longitudinal indentation, a corresponding number of girders fitting into said indentations and secured to the bottom of said hill] to provide a stable lateral support for said tubes, and an outer flexible cover having its edges secured to said rigid hull and'providing a smooth, air-tight enclosure of said air tubes.

9. In a flying boat, the combination of a hull of rigid construction and a resilient landing cushion underneath the bottom of said hull, said cushion comprising a plurality of longitudinal separately inflatable air tubes substantially parallel to each other, a step dividing the landing cushion into a front portion and a rear portion, the tubes in said front portion being larger in diameter than corresponding tubes in the rear portion and each having on top a longitudinal indentation, a. corresponding number of girders fitting into said indentations and secured to the bottom of said bull to provide a stable lateral support for said tubes, and an outer flexible cover having its edges secured to said rigid hull and providing a smooth, air-tight enclosure oi said air tubes, the width of the front portion of said cushion being substantially the same as that of the bottom of the rigid hull and the width of the rear portion diminishing rearwardly from said step to give streamline effect.

10. In a flying boat, the combination of a hull of rigid construction and a resilient landing cushion underneath the bottom of said hull, said cushion comprising a plurality of separate inflatable air tubes, each of which has on top a longitudinal indentation, a corresponding number of girders fitting into said indentations and secured to the bottom of said hull to provide a stable lateral support for said tubes,'and an outer flexible cover having its edges secured to said rigid hull and providing a smooth, air-tight'enclosure of said air tubes, said outer flexible cover aswell as the air tubes being formed of treated fabric and assembled in streamlin form.

ll. In a flyingboat, the combination of a hull of rigid construction and a resilient landing cushion underneath the bottom of said hull, said cushion comprising a plurality of separate inflatable air tubes, each of which has on top a longitudinal indentation, a corresponding number of girders fitting into said indentations and secured to the bottom of said hull to provide a stable lateral sup- 'port for said tubes, an outer flexible cover having its edges secured to said rigid hull and providing a smooth, air-tight enclosure of said air tubes, said outer flexible cover as well as the air tubes being formed of treated fabric and assembled in streamline form, and flexible chafing strips longitudinal of and fixed to the outer surface of said cover for protection.

KARL ARNSTEIN. BENJAMIN J. SCHNITZER.

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