US3384183A - Inflatable vane - Google Patents

Description

y 1968 T. s. BRAVERMAN 3,384,183

INFLATABLE VANE Filed May a, 1967 INVENTOR THEODORE S.BRAVERMAN MJMA ATTORNEY United States Patent 3,384,183 INFLATABLE VANE Theodore Stanley Braverrnan, 27-21 203rd St, Bayside, Queens, N.Y. 11360 Filed May 8, 1967, Ser. No. 636,837 Claims. ((1 170-159) ABSTRACT OF THE DISCLOSURE The invention relates to an inflatable propeller which is made of rubber or the like. The propeller comprises an elongated body having a fluid expandable chamber therein and a valve means for introducing fluid into the fluid expandable chamber. The propeller also includes a hub, said hub being provided with a pump arrangement therein. A pressure sensitive valve is connected between the pump arrangement and the fluid expandable chamber for maintaining a pressure gradient between the chamber and atmosphere.

The present invention relates to an inflatable air foil and more particularly to an inflatable aeronautical propeller blade or blades or helicopter and/or movable air foils for airborne vehicles.

Heretofore, it has been known in the prior art of airplane propellers that dirt in the form of rocks and pebbles are kicked up during an airplanes operation on the ground. It is further of record that debris in general impinges on the airplane propeller blades not only on takeolf and ground operations but at other times both during and prior to the airplanes becoming airborne.

Those skilled in the art recognize that this occurrence is most prevalent during the pre-flight check which the pilot makes since he is generally parked at one end of the runway and powers his engine to make certain checks before take-oif. Of course, this impinging of dirt and rocks is not limited to the pre-flight check period but is also frequently happening during take-01f as well as landing, and taxiing.

Since these rocks and pebbles are kicked up, their most natural point of impingement is upon the Leading edges of the propeller blades of an airplane. This problem has recently been aired in the magazine Private Pilot, the issue dated October, 1966, and again treated in the December, 1966, issue of Flighing, and adds to the knowledge of those skilled in the art. To wit, that the impinging pebble on the leading edge of the air foil causes indentations and holes therein. These indentations, although innocent in appearance, may become the points of a shearing stress in flight, due to the flexing of the air foil, and concentration of stresses at this point results in the failure of the indented air foil.

Further, these indentations commonly lead to failures such as fracturing of a portion of the blade which results in vibratory forces caused by the imbalance of the blade during flight which may result in other serious complications such as loosing the engine from its mounts and reducing the use of full power of the engine because of the vibratory forces created.

Various attempts have been made by those skilled in the art to remove or negate the structural failure created by the nicks or indentations in the propeller blades but to date there appear to be little or no adequate means of prevention, since none of the major manufacturers of propeller blades has brought forth a propeller which overcomes the aforementioned difliculties.

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Since the problem is one that is well recognized by those skilled in the art, it is abundantly clear that to date, until this disclosure, no adequate solution has been found.

It is the object of the present invention therefore to avoid and overcome the difliculties and other objections to prior art devices by providing a sturdy, resilient and relatively inexpensive inflatable propeller blade.

It is the primary object of the present invention to provide an inflatable propeller blade using resilient material which will avoid and overcome the prior art failures.

Another object of the present invention is to provide a propeller blade which will negate or drastically reduce the susceptibility of the rotatable air foil to forces created by the indentations and nicks on the leading edge of the retating air foils.

A further object of the present invention is to provide an inflatable propeller blade of relatively resilient material which will decrease the incidents of indentation and nicks in the propeller blade.

Still another object of the present invention in one of its forms is to provide a rotatable air foil which may be readily mounted and dismounted when desired.

A further object of the present invention in one of its forms is to provide a rotatable air foil of one piece construction.

Yet a further object of the present invention is to provide an inflatable rotatable air foil which will be structurally superior and the rigidity of the air foil can be controlled as desired.

Yet another object of the present invention is to provide an inflatable air foil which may have its internal pressure controlled so that the internal pressures of the inflated air foil may be varied in accordance with the ambient temperatures and pressures thus providing a constant pressure gradient between the internal chamber and atmosphere regardless of the changes in the atmospheric pressure.

Still another object of the present invention is to provide an inflatable propeller blade to be used in combination with a pump means for supplying and maintaining the inflated propeller blade at proper rigidity during flight periods.

The principles of the present invention have been achieved by providing an inflatable air foi-l comprising an elongated body member in the well known shape of an airplane or helicopter propeller, said body member being composed of a relatively resilient material, at least one fluid expandable chamber disposed within said body member, connecting means disposed on said body member for releasably securing said body member to the hub of an airplane, valve means in communication with at least one of said fluid expandable chambers to introduce and remove fluid internally of said body member and in communication with said fluid expandable chambers for inflating said propeller blades, and a means for balancing the propeller blades.

For a better understanding of the present invention reference should be had to the accompanying drawings, wherein like numerals of reference indicate similar parts throughout the several views and wherein:

FIGURE 1 is a plan view of the air foil,

FIGURE 2 is an end view of the air foil,

FIGURE 3 is a section taken along lines 33 of FIG- URE 1,

FIGURE 4 is a cross sectional view of the hub,

FIGURE 5 is an alternative connecting arrangement of the air foil, and

FIGURE 6 is a cross sectional view of a modified form of the air foil.

Although the principles of the present invention may be broadly applicable to air foils of airplanes, helicopters and other air vehicles, it is particularly understood that the present invention is particularly well adapted for use in conjunction with airplane propellers and hence it has so been illustrated and will so be described.

With specific reference to the form of the present invention illustrated in the drawings, and referring particularly to FIGURES 1 and 2, an inflatable air foil is indicated generally by the reference numeral 10.

Although the present invention contemplates the use of a form of natural and/or synthetic rubber as the principal material, it should be particularly understood that other forms of material exhibiting the proper resiliency, hardness, inflatability and other pertinent properties may be utilized. For example, certain plastic materials and other forms of synthetic materials such as plastics and nylons as well as rubber or any combination thereof may be used. Further, it is contemplated that the particular material utilized as the basic structural material may be reinforced in a manner such as automobile tires with the use of nylon cord or any other synthetic cord material which will present a reinforced structural material.

For the sake of convenience only, however, the structural material referred to in the foregoing description will be rubber.

As shown in FIGURES 1 and 2 the general shape of the air foil, hereinafter referred to as a propeller blade 10, is taken in its inflated form and mounted upon a hub 12. The propeller blade 10 is provided with a leading edge 14 and a trailing edge 16. As previously stated, the inflated propeller blade 10 will take the general overall shape of the well known propeller blade. 7

As shown in FIGURE 2, the aeronautical propeller blade 10 is provided with an outer wall 18 and thereby creating at least one inner chamber 20. However, as shown in FIGURE 2, a pair or more of inner chambers 20 may be provided by introducing a reinforcing wall 22 running vertically or horizontally within the propeller blade 10.

The construction of the preferred embodiment contemplates a pair of blades 10 integral with each other and having connected between the pair, ring-like hollow member 24 which may be mounted upon the hub ridge 26. FIGURE 3 shows a first blade member 28 and a second blade member 30 in its inflated form connected to the ring-like hollow member 24.

The outer tips 34, 36 of the aeronautical propeller blades may be provided with a plurality of holes 38 which may accommodate various types of balancing devices 40 for providing a balance of the first blade member 28 and the second blade member 30.

Further, similar type holes 38 may be provided at the trailing edge 16 (not shown) employing similar balancing devices 40 so that the propeller blade or air foil 10 may be balanced.

Other types of balancing means (not shown) may be provided such as a block of material either at the tip of the blade or trailing edge 16 integral with the air foil which may be shaved to accomplish the balancing thereof. In either case, the balancing means are completely within the control of the maintenance of the air vehicle so that various forms can be utilized and any previously described combination.

At the inner extremities 42, 44 of each first propeller blade member 28 and second propeller blade member 30 respectively there may be provided a rigid protrusion 46 around the ring like hollow member 24 to provide a means .of fixedly mounting the entire aeronautical blade propeller or air foil 10 structure on the hub 12.

It may be seen therefore that when the chambers 20 are filled with fluid, the outer walls 18 will assume the shape of an airplane propeller and maintain the shape as long .4 as the pressure in the respective chambers 20 is suflicient to keep the outer walls 18 rigid.

It is well known to those skilled in the art that the various temperature and altitude changes during the flight of an air vehicle may cause any inflated object to either expand or contract due to the pressure gradient change in the altitude in which the plane is flying. Further, it is necessary that the internal pressure within the chambers 26 be maintained such that the propeller blades 10 will remain rigid during the course of the flight since the lead ing edges 18 and the propeller blades 10 in general are subjected to extreme stresses and pressures during their normal use in flight. To this end, at least one pump 48 may be provided as shown in FIGURE 4 wherein a constant pumping action is maintained so that the fluid pressure within the chambers 29 of the propeller blades 28, 30 are maintained such that a relatively rigid outer wall construction is possible during the flight of the air vehicle.

As shown in FIGURE 4, a convenient location for such a pump arrangement 48 may be found in the hub 12 of the air foil itself. It may be seen that more than one pump 48 may be disposed within the hub 12, as a back up. With the proper passage arrangement and pressure sensitive valves the pressure relationship between the atmosphere and the internal chamber 20 of the propeller blade It] may be maintained at a constant predetermined value.

structurally, as shown in FIGURE 4 at least one pump 48 may be disposed within the hub 12 of the air foil 10. To this end the hub 12 may be provided with a piston bore 50 disposed such that it does not interfere with the operation of the crankshaft 52. A piston head 54 may be reciprocably mounted within the piston bore 50 which Works against the expansion resilient member 56. The rear 58 of the piston head 54 may have connected thereto a piston rod 60 which protrudes rearwardly out of the piston bore 50 in the direction of the airplane engine (not shown). At the rearward portion d2 of the piston rod 60 a strike plate 64 may be provided which when in contact with the cam 66, mounted on the airplane engine, such that when the hub rotates the striker plate 64 will contact the cam 66 thereby intermittently forcing the piston head to reciprocate.

Since the piston head 54 works against the resilient member 56, it may be seen that after the cooperation of the cam 66 and striker plate 64 urges the piston head 54 forwardly, the resilient member 50 thereafter forces the piston head 54 rearwardly so that the striker plate 64 is in position to engage the cam 66 on the following rotation of the hub 12.

As shown in FIGURE 4, a fluid chamber is disposed in the piston bore 50* such that when the piston head 54 is urged forwardly through the cooperation of the cam 66 and striker plate 64 any fluid in the piston bore 50 will be forced out thereof through a passage 70 and 70A into the chambers 20 within the air foil 10. A passage 72 may be provided in the hub 12 with check valve 74 so that after the fluid in the fluid chambers in the piston bore 50 has been forced into the chambers 20 of the air foil 10, and the piston head 54 has been urged rearwardly by the resilient member 56, fluid from the atmosphere may enter the bore 50. Further, the check valve 74 will permit the venting to atmosphere of fluid when the pressure gradient is at an acceptable level. Manifestly, the check valves 74 will be set to prevent the fluid in the fluid chamber of the bore 50 from escaping through the passage 72.

It should be remembered that the primary purpose of the pump 48 and its back up 48' is to maintain the proper pressure gradient between atmosphere and the internal pressure of the air foil. To this end a pressure sensitive valve member (not shown) connected in passages 70, 70A must in essence be attuned or set to permit the passage of fluid from the fluid chamber of the bore to the chambers 20 in the air foil 10, only when the pressure gradient requirements are not satisfied. Valve members of this type are commercially available and any convenient pressure sensitive valve may be used to perform this function. Similarly it must be recognized that in the event the proper pressure gradient is maintained, the pumping of the fluid in the fluid chamber of the bore 50 will continue, however, instead of the fluid being pumped into the chambers 20 of air foil 10, the fluid may be permitted to be dissipated to atmosphere through the check valves 74.

A back up pump arrangement 48' is shown in FIG- URE 4 and its operation is identical to that already described in detail.

Since icing is a problem at the leading edge portions of any air vehicle any of the passages venting to atmosphere should be disposed at those areas least susceptible to icing.

Alternatively, as shown in FIGURE 6, a molded, one piece air foil 76- may be provided which will accomplish and satisfy the requirements fulfilled by the preferred embodiment. Structurally, a pair of bladders 78 with accompanying air lines 80 may be provided and the one piece air foil 76 may be molded therearound so that a member of unitary construction will be provided. Although different from the air foil 10, the one piece molded air foil 76 will have certain overall similarities to the disclosed preferred air foil 10. For example, the one piece molded air foil 76 may be provided with a first blade 82 and a second blade 84 each of which are inflatable or deflatable through the expansion or collapsing of the bladders 78 simultaneously or independently. The blades 82, 84- are integrally molded to a connecting plate 86 which may provide for the housing of the pump 48'. Further, the connecting plate 86 may be provided with a multiplicity of holes 88 so that the one piece air foil 76 may be releasably secured to the hub 12'. Although only one air chamber is shown in each propeller blade 82, 84, it will be recognized, based on this disclosure, that more than one bladder may be utilized in each propeller blade thereby creating a multi-chamber arrangement similar in nature to that described in connection with the preferred embodiment.

The one molded piece air foil may utilize the exact same pressure; gradient maintaining apparatus as described in conjunction with the preferred embodiment since the problems of maintaining the pressure gradient are exactly the same.

A further alternative embodiment may be provided, in that, rather than having two blades integrally made with a connecting means therebetween, individual blades may be mounted into the hub 12. The individual blade may be of similar internal structure of the preferred embodiment, however the means of connection to the hub, of necessity, would be slightly different. It should be noted in this connection however, that the valving arrangement previously described would apply to the individual blades 90 or any of the other embodiments.

It should be noted that in the cases of the alternative embodiments, the essence of the invention is not in any manner departed from but are merely variations of structure.

Although the invention hereinabove described contemplates the use of rubber as the basic material for the inflatable air foil, it should be understood that other materials and combinations thereof may be used. Recent articles substantially show the advantages of rubber over materials such as wood or aluminum in that hard rubber is lighter in weight and in many instances more difficult to damage than either of the other materials above mentioned. Rubber further exhibits the necessary resiliency to reduce the nicks and pots which may be created by the impinging of pebbles and the like on the leading edges of the air foils. i

In carrying out the objects of the present invention,

it will be recognized by those skilled in the art that the invention hereinabove described provides for an inflatable air foil for airplanes, helicopters and other air vehicles which utilize rotating air foils such that the serious in flight problems of blade failure is reduced or eliminated.

While in accordance with the patent statutes a perferred and alternative embodiment are herein shown and described, it is particularly understood that the invention should not be limited thereto or thereby.

I claim:

1. An inflatable air foil for air vehicles comprising an elongated body, said elongated body being composed of relatively resilient material, at least one fluid expandable chamber disposed within said body member, means disposed on said body member for releasably securing said body member to the hub of an air vehicle, valve means in communication with at least one of said fluid expandable chambers, at least one pump arrangement disposed in the hub for maintaining said air foil in its inflated condition, and a pressure sensitive valve connected between said pump arrangement and said fluid expandable chamber for maintaining a pressure gradient between the expandable fluid chamber and atmosphere.

2. An inflatable air foil according to claim 1 wherein said elongated body is in the form of a first propeller blade and a second propeller blade, said means disposed on said body member being disposed between said first and second propeller blades.

3. An inflatable air foil according to claim 2 wherein at least one fluid expandable chamber is disposed within each of said first and second propeller blades.

4. An inflatable air foil according to claim 3 wherein the hub is provided with a recessed annular portion, said means disposed on said body member connected between said first and second propeller being connectable into said recessed annular portion thereby holding said first and second propeller blades on said hub.

5. An inflatable air foil according to claim 4 wherein a plurality of passages connect said pump arrangement to said first and second propeller blades so that fluid may be pumped thereinto during the flight of the air vehicle.

6. An inflatable air foil according to claim 5 wherein a cam is connected to the air vehicle so that at each rotation of said hub the pump arrangement will be activated at least once to force air into said fluid expandable chambers.

7. An inflatable air foil according to claim 6 wherein said pressure sensitive valve is disposed in a passage communicating between said pump arrangement and atmosphere, said passage venting to atmosphere at an area of said hub which is not susceptible to icing.

8. An inflatable air foil according to claim 7 wherein a second valve arrangement is provided in said hub, said second pump arrangement being provided with passages leading therefrom to said fluid expandable chambers, a second pressure sensitive valve disposed in a second passage communication between said second pump arrangement and atmosphere, said second passage venting to atmosphere at an area of said hub which is not susceptible to icing, said second pump arrangement operating alternately with said first mentioned pump arrangement.

9. An inflatable air foil according to claim 1 wherein said air foil is of unitary construction, at least one inflatable bladder disposed in said body member which is to be filled with fluid pumped thereinto, said unitarily constructed air foil being provided with a connecting means ,and being integral with said body member for securing said air foil to said hub, sad body member being formed into a first propeller blade and a second propeller blade, said at least one being disposed within each of said first and second propeller blades, and at least one pump arrangement disposed within said hub being connected to each of said at least one bladder for maintaining fluid with the bladders.

10. An inflatable air foil according to claim 9 wherein a second pump arrangement is provided and being connectable to said at least one bladder, said second pump arrangement capable of operating alternately with said first mentioned pump arrangement.

References Cited UNITED STATES PATENTS EVERETTE A. POWELL, J R., Primary Examiner.

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