US1363692A - Aeroplane-propeller - Google Patents

Description

E. W. SUMMERS.

AEROPLANE PROPELLER.

APPLICATION FILED our. 23, 1917.

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A TTORNE Y E. w. SUMMERS.

AEROPLANE PROPELLER.

APPLICATION FILED OCT- 23, I917.

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A TTORNEY EDGAR W. SUMMERS, 0F PITTSBURGH, PENNSYLVANIA.

AEROPLANE-PROPELLER.

Specification of Letters Patent. P t t d D 28 1920.

Application filed October 23, 1917. Serial No. 198,029.

To all whom it may concern:

Be it known that I, EDGAR W. SUMMERS, a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Aeroplane-Propellers, of which the following is a specification.

This invention relates to air screws or propellers, and more particularly to screws or propellers for use in aeroplanes, dirigibles, balloons, etc.

W'hile it has been proposed to form aeroplane screws or propellers from sheet metal, such propellers are today largely made of wood, generally laminated. They are roughly shaped by machinery but the final shaping must be done by hand, and since the contour must be very exact, specially skilled men are required for finishing them. It has been found that few men can be trained for this work, but that it requires men who have a knack or special aptitude for the work. The result is that the manufacture of such propellers is not only slow and expensive, but because of the inability to train men for finishing them, the output is, and must necessarily be, rather limited.

Furthermore, these propellers usually comprise two blades in a single piece, and it is the practice to hand finish the complete propeller so as to have the same accurately balanced, and in the event that any one of the blades is injured, it is necessary ture to take off a blade at one end and reto discard the entire propeller as it is not possible in the present methods of manufacplace it with another.

Furthermore, there is always danger of the wood warping after the blade is finished, and the laminated wood is also affected by climatic conditions, such as heat and moisture. Also, in making these wooden blades, due to the twist which must be in the blades, the wood is necessarily cut insome part of the blade across the grain and frequently the blades break at these cross-grain portions.

The object of my invention is to provide a propeller blade which is free from-the difficulties above mentioned; one which can be expeditiously made in large quantities and without requiring men having such a high degree of skill or special adaptability as above mentioned; which is made in such way that each and every blade of a given size and design will be an exact duplicate of every other one, so that in case a blade is injured it will be possible to substitute a new blade from stock; one which is stronge" than a wooden blade and in which the stresses can be calculated and the blade reinforced with material of a known strength to resist the stresses; and one which is not affected by climatic conditions.

For the attainment of the foregoing objects the propeller blade is formed by die shaping sheet metal, preferably in parts, and uniting these parts to form a hollow body whose external contour conforms to the best propeller shape or design, said body being internally braced against collapse and internally reinforced wherever required to provide the necessary strength.

The accompanying drawings illustrate one form of the improved propeller. In these drawings, Figure 1 is a face or plan View of one of the blades; Fig. 2 is a transverse section thereof on an enlarged scale, on the line 2-2, Fig. 1; Fig. 3 is a face view of the hub portion of the propeller illustrating one manner of connecting the blades to the hub; Fig. 4 is a sectional View on the line 44 of Fig. 3; and Figs. 5 and 6 are views correspondlng to Figs. 3 and 4 (Fig. 6 being a section on the line 6-6, Fig. 5) and showing a modified form of construction.

The drawings show the external shape of the propeller blade only in a general way, it being understood that the exact external contour will be varied to meet different conditions, and can be made anything that the best engineering practice may dictate. Such blades, as is well known, have a twist from the hub or boss end to the tip end, and this is indicated in a general way 1 n Fig. 1, but has not been illustrated in detail because the invention merely has to do with the construction of the blades, which construction' can be adapted to various con.

forming what may be termed the flatter'or the working face of the blade and a sheet 3 forming the more rounded or curved face of the blade. In Fig. 1, the face 2 of the propeller is shown, and in Figs. 1 and 2, the edge portion marked 4 is the forward or air clevage edge of the blade and the edge marked 5 is the rear edge thereof. The arrows on the drawings indicate the direction of rotation. The two plates 2 and 3 have their edges secured together all around the blade in any suitable way, such, for instance, as by soldering or brazing, but preferably by welding, which can be expeditiously done by the electrical process. These sheets will be formed to the desired contour by pressing in dies, and obviously after a set of dies have been accurately made, then comparatively unskilled labor can produce the sheets in almost unlimited quantities, and with the assurance that all sheets will be exactly allke, thus insuring propeller blades which are exact duplicates of each other.

These blades can be made of very thin sheet metal, thus rendering them very light, and in order to strengthen them against collapse, they can be, and preferably are, internally braced and reinforced in any suitable way. Figs. 1 and 2 show one form of bracing, the same comprising a metal sheet 6 extending lengthwise of the blade for the major portion of its length and formed into a zig zag or corrugated shape and united to the two face plates alternately, as at the polnts 7 and 8 respectively. This union can also be formed in any suitable manner, but preferably by electric welding as above described.

In constructing the blade, the sheets are first die pressed to the proper shape, after which the brace member 6 is united to one of the sheets, such as by welding it to the sheet 3 at the points 7. The other sheet, such as sheet 2 is then welded to the brace member at the points 8, the inner terminal of the electric welder being inserted through the open hub or. boss endof the blade. Lastly, the edges of the two sheets are welded together as above described.

While assembling and welding these parts, they are held in suitable jigs to hold them in proper shape and in pro-per position relative to each other.

The blade is reinforced to give the necessary strength at any point, and especially at the boss or hub end where the stress is greatest. Such reinforcement is preferably applied internally so as not to interfere with the external contour of the blade. The'brace sheet 6 reinforces the body of the blade, and

such as by electric welding. These reinforcing members at their hub ends are widened out to conform to the shape of the blades 2 and 3, and they extend toward the tip for the desired distance and gradually taper off or become narrower as they extend outwardly. If great strength is required, several such reinforcing plates of progressively cylindrical form externally and the blades at their hub ends are widened out to form segmental portions 13, each extending for approximately 120 degrees and fitting against the exterior of the hub 12. Inside of the portions 13 of the blade is a rmg shaped brace member 14, preferably having its edges flanged, as at 15, to extend toward the boss or hub, and secured to the blades, such as by welding the flanges 15 to the inner faces of the blades. The abutting edges of adjacent blades are also welded together, such as on the lines 16. On each face of-the propeller is provided a sheet metal ring or face plate 17 which is welded along its edge to the blade, on the line 18, or at any other desired places, and which has its inner edge flanged outwardly, as at 19 and welded to the boss or hub 12.

In assembling the propeller with this construction, the blades with the reinforcing plates 9 and 10 secured therein are assembled in a suitable jig with the interior bracing ring 14, the abutting edges of the segmental portions of the rings are welded together on the lines 16, after which the face plates 17 are put in place and welded at their edges 18 to the outer faces of the blades at one an the same time that the ring 14: is welded to the inner faces of the blades at 15. Between the blades on the periphery of the hub where there would otherwise be open joints, small pieces of plate 20 are welded to the outer face of the segmental portions 13 of the blades. All of this welding must be done before the boss hub is put in place in order that one of the welding terminals can be gotten to the interior of thewheel. Finally, the hub is put in place and welded to the flanges 19 of the plates 17 Figs. 5 and 6 illustrate a construction in which the blades are fastened to the hub in a manner to permit any one of the blades to be readily removed and replaced by an,- other. As here shown the boss or hub 12 has a central enlarged portion 12 provided with a series of bolt holes 22. The segmental portions 13 of the blades are extended eas es somewhat beyond 120 degrees, so as to provide perforated ears 23, one of which is olfset so as to overlap the ear of the adjacent blade. The segmental portions are also provided with holes or perforations and bolts 25 or similar fastening means are passed through these holes and the holes 22 in the boss hub, thus fastening the blades to the boss or hub and to each other. In this construction the segmental portions 13 of the blades are preferably flanged outwardly, as at 26, to embrace the reduced end portions of the boss or hub, but if desired the face members'17,'shown in Fig. 4: may be applied, such members in this instance, being perforated for the bolts 25.

The screw or propeller described is light and yet strong, the method of construction is such that the blades can be. formed expeditiously in large quantities and with the assurance that each is an exact duplicate of the others. Consequently, if a blade is injured, the entire propeller need not be scrapped, but the injured blade can be removedand replaced by an exactly similar one. The blades shown in Figs. 5 and 6 can be replaced in' the field, but the propeller or screw shown in Figs. 3 and a must be returned to a shop to have the injured blade taken out and a new one put in.

The fabrication of the blades does not require such highly skilled labor or men having a special aptitude for the work asin the manufacture of wooden propellers. After the dies have been accurately formed, it becomes a simple die stamping operation,

and as is well known, the parts can be.

formed by die pressing to an accuracy of one one-thousandth of an inch. The electric welding can be readily and cheaply done,

and as this means merely heats the parts locally, it does not result in injurious distortion of the blade. Care will be taken to weigh and adjust all of the component parts of a blade beforeit is assembled, determining and making their centers of gravity all alike and also making their rotative Inoments alike about the center of rotation in the propeller. If after assembling the propeller should be out of balance, it can be readily remedied, either by removing a little of the surface of the metal, or by adding weight at the necessary point, such as by coating the plates with fluid metal. of any kind or adding metal in any other form at the point where the weight is deficient.

The blades are susceptible to a very high polish on the exterior, and if for ed of steel or other corrodible metal, can be c ated with suitable non-corrodible. metal, preferably from the contained air. The blades will have their hub ends closed to prevent the entrance of moisture or other substances.

What I claim is 1. An air screw blade comprising a hollow sheet metal body provided with longitudinally extending internal bracing and with an internal reinforcement at the hub end extending over and enveloping the hub and projecting toward the tip of the blade.

2. An air screw blade comprising a hollow body formed or die-shaped sheet metal mem bers united at their edges and provided with longitudinally extending internal bracing secured to the opposite side walls of said body and at the hub end being provided with internal reinforcement surrounding and enveloping said hub and projectingtoward the ti of the blade.

3. in air screw blade comprising a hollow body formed of die-shaped sheet metal members welded together at their edges and provided with internal bracings extending longitudinally of the blade and welded to the opposite walls thereof, and at the hub end provided with internal reinforcement :extending over andj enveloping said hub andprojecting toward. the tip of the blade.

sheets shaped to provide the proper exterior contour of the blade and united at their edges, an internal bracing comprising continuous zig zag shaped members extending longitudinally of said body'and secured alternately to opposite side walls thereof and dividing the hollow interior into triangular shaped cells, and internal reinforcement at the hub end extending over and enveloping the hub and projecting toward the tip of the blade.

5. An air screw or propeller blade comprising a hollow sheet metal body formed of sheets shaped to the proper exterior contour and united at their edges, and internal reinforcement plates in said blade at the hub end and projecting toward the tip of the blade, both said blade and internal reinforcement plates extending over and enveloping the hub, and securing means fastening both said blade and reinforclng plates to the hub.

' 6. An air screw or propeller blade comprising a hollow sheet metal body formed of sheets shaped to the proper exterior contour and united at their edges, and internal-reinforcement plates in said blade at the hub end and projecting toward the tip of the blade, both said blade and internal reinforcement plates extending over and enveloping the hub, and securing means extending through said blade and reinforcemeznt lates and into tliehub.

11 air screw comprising .hollow sheet metal blades having their boss or hub ends lso formed segmental to embrace the hub and having segmental portions of adjacent blades united, and a boss or hub embraced by said segmental blade portions and'united thereto by means placed in shear.

8. An air screw comprising hollow sheet metal blades having their boss or hub ends of segmental form to embrace the boss or hub and With the outer ends of the segmental portions of adjacent blades united to each other, an internal annular bracing surrounding the boss or hub and united to the Walls of the blades, and aboss or hub fitting in said segmental portions and united thereto.

9. An air screw comprising hollow sheet 15 metal portions having their boss or hub ends of segmental form to embrace the boss or hub, a boss or hub fitting in said segniental portions, and detachable means uniting said blades to each .other and to 20 the boss or hub, said securing means being in shear.

In testimony whereof I have hereunto set my hand. 1

' EDGAR W. SUMMERS.

Witness:

GLENN H. LERESGHE.

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