US2334118A - Protection of propeller blades - Google Patents

Description

Nov. 9, 1943.

J. F. MORSE ET AL 2,334,118 PROTECTION OF PRO PELLERBLADES 7 Filed March 28, 1939 2 Sheets-Sheet 1 Jahn F ZZ E027 L Tay/aa Nov. 9, 1943. J. F. MORSE ETAL 2,334,118

PROTECTION OF PROPELLER BLADES 2 Sheets-Sheet 2 Filed March 28, 1939 rzLfTvibzi 4 Jahn EJ251255 flysan .L 7755 [0 Patented Nov. 9, 1943 PROTECTION OF PROPELLEB BLADES John F. Morse and Myron L. Taylor, Hudson,

Ohio, assignors to The B. F. Goodrich Company, New York, N. Y., acorporation of New York Application March 28, 1939, Serial No. 264,575

19 Claims.

This invention relates to the protection of propellers, especially the blades of airplane propellers, and the invention provides improved means for preventing the accumulation of ice on propeller blades.

Because the accumulation of ice upon the blades of airplane propellers objectionably afi'ects balance, causes undesirable vibration, reduces aerodynamic efficiency and is undesirable also in other respects the provision of means for effectively preventing ice accumulation on propeller blades is important.

A device used for resisting ice'accumulation heretofore, known as the slinger ring," has comprised an annular trough-like structure at the hub of the propeller with supplying means for the trough and a short metal tube leading from the outer periphery of the trough to a position at the root of the blade. An anti-freeze liquid, fed into the trough and conducted radially outward under the action of centrifugal force, has been discharged at the root of the blade for the purpose of spreading upon the blade to loosen ice accumulated thereon to prevent the accumulation of ice. Such device has had the disadvantage that the desired degree of uniformity of distribution of liquid upon the blade has not always been effected, the liquid often having been blown away by flow of the air without adequate distribution upon the blade, and at best the liquid has covered only an undesirably small area of the blade. v

Also, the bare propeller blades heretofore have been subjected to undesirable abrasion asa result of impact by dust, stones, and other matter in the air, especially in the case of metal propeller blades, the nicks of such abrasion having tended to weaken the propeller blade which is considerably stressed at its surface, and having required frequent reworking and replacement of the blades to maintain adequate safety and efllciency of operation.

a The chief objects of the present invention are to provide improved protection of the blade, to

from the following description, reference being had to the accompanying drawings in which:

Fig. 1 is a front elevation of a two-bladed airplane propeller assembly having mounted thereon protective means constructed according to and embodying the invention. For convenience of illustration, the left-hand blade is shown protected according to one embodiment of the invention and the right-hand blade is shown protected according to another embodiment of the invention, it being preferred that in a particular installation, all the blades will be protected uniformly by the same construction.

Fig. 2 is a plan view on an enlarged scale of a portion of the assemblyof Fig. 1, including a portion of the hub and right-hand blade, parts being broken away.

Fig. 3 is a rear elevation of the structure of Fig. 2. Fig. 4 is a plan view of the fluid-conducting structure of Fig 2, the parts being shown in their flat state before application to the propeller blade, and parts being broken away.

Fig. 5 is a section taken along the line 5-5 of Fig. 4.

Fig. 6 is a section taken along the line 6- -B of Fig. 4.

Fig. '7 is a section taken along the line |--'I of Fig. 1.

Fig. 7A is a section taken along the line la-10 of Fig. l.

Fig. 8 is a section taken along the line 8-8 of Fig. 4.

Fig. 9 is a perspective and sectional view of a modified form of blade protective strip shown in its fiat state before its application to the propeller.

Fig. 10 is a plan view of a further modified form of blade protecting strip shown in its fiat state beforeits application to the propeller.

Fig. 11 is a section taken along the line ll'-l| of Fig. 10.

Fig. 12 is a section taken along the line I2--i2 of Fig. 10-.

Fig. 13 is a fragmentary view of the under side of the strip of Fig. 10.

Fig. 14 is a cross section'of the leading edge of a propeller blade having the strip of Fig. 10 mounted thereon, parts being broken away.

Fig. 15 is a perspective and sectional view of a still further modified form of protective strip shown in its flat state before its application to the propeller.

still further modified construction.

along its leading edge and for releasing .suclr liquid at spaced-apart positions along the blade in such manner that the liquid will be caused by the movement of the blade to flow over the surface thereof to loosen ice accumulated thereon or to prevent the accumulation of ice. The

distribution and release of the liquid along the.

blade is effected in such a manner that minimum of the liquid is released to the air without first flowing over the blade surface, and in a manner such that the liquid is well distributed over the surfaces that are subject to ice accumulation.

The protective covering or shoe preferably is.

of vulcanizable rubber-like material, such for example as rubber composition, neoprene or other so-called synthetic rubber, or even non-vulcanizable rubber-like material such as plasticized vinyl chloride, which materials may be molded to shape and have high abrasion resistance, but the liquid-distributing passageways may-be provided in coverings of wood, metal or other suitable material, or even in the blade proper, if desired.

Provision is made for conducting the liquid to the distributing passageways while permitting adjustment of the blade in a variable pitch propeller. Further provisions will be apparent as the description proceeds.

In Fig. 1 the invention, in two alternative embodiments is applied to the blades 20, 2| of the two-bladed propeller mounted upon a hub structure 22 having mechanism therein for varying the pitch of the propeller blades, which pitch-varying mechanism may be of any suitable construction.

At the leading edge of blade 20 is mounted a shoe 23 extending along the blade for a sufficient distance to include the icing region. Ordinarily about two-thirds of the length of the blade from the root toward the tip is sufficient, but if desired the shoe may extend a lesser or greater distance alongthe blade, or even throughout the whole length of the blade if desired. The shoe 23 preferably is of rubber-like material, as hereinbefore described, which material may be readily molded or otherwise formed to provide passages for conducting fluid, and

h which material is readily attachable to propeller blade surface by a strong adhesion or.

bond, and which further has the advantage of good resistance to abrasion. In the embodiment of Figs. 1 to 8 the shoe 23 is formed in its outer surface with a plurality of grooves 24, 24, 25, 25, 26, 2B, and 21, 21 extending peripherally outward from the root portion, these sets of grooves terminating at spaced-apart positions along the shoe, and each groove terminating preferably in a gradually sloping end surface 28 as shown in Fig. 8. The sloping bottom 28 of the groove has the advantage that the liquid will spill out of thegroove gradually rather than abruptly and over a considerable zone. 'If desired, the slope 28 may be extended, or the groove may be otherwise gradually constricted over a zone nearing or even overlapping the end of an adjacent groove to provide for releasing the liquid evenly all along the shoe.

The shoe may be of small thickness so as not to have a considerable mass itself subject to the centrifugal force, and the margins of the shoe are bevelled as at 29 and 30 sothat the surface of the shoe will merge with the surface of the propeller blade. The shoe may be molded or otherwise formed in the flat and then fitted to the contour of the blade, to which it is ad- .hered by an adhesive 3| which may be of a vulcanizable cement or a so-called air-curing cement or any other suitable adhesive.

For conducting the liquid into the grooves, a manifold strap 32 is provided'at the inner end of the shoe 23. extending transversely thereto and adapted to be wrapped around the propeller blade at its root. The manifold 32 may be molded or otherwise formed of the same material as the shoe andpreferably is vulcanized integrally with the shoe. The grooves of the shoe communicate with a manifold passage 33 of the strap which passage conducts liquid from an inlet nipple 34. A suitable fabric reinforce- .ment 35, preferably of square woven fabric, may

be incorporated in the strap 32, and if desired a similar reinforcement 36 may be provided beneath the grooves in the shoe 23 and may extend the full length thereof. The strap 32 has a raised central portion 31 with depressed sides 38, 39, the latter being for the accommodation of holding bands 46, M respectively, encircling the root of the propeller blade. These bands may be of metal having their ends bolted as shown in Figs. 2- and 3 or they may be of ad hesive tape pr any other suitable construction.

At the rear of the propeller hub is provided an annular trough 42, itself of known construction, for picking up liquid deposited in it from a non-rotating feed pipe, and for transmitting the liquid outwardly at its periphery to a discharge nipple 43. In accordance with the invention there is provided a flexible hose connection 44 of rubber or other flexible material, between the nipple 43 of the trough 42 and the nipple 34 of the manifold, to conduct the liquid from the trough into the manifold which feeds the liquid into the grooves of the distributing shoe. Owing to the flexible connection 44 adjustment of the propeller blade to vary its pitch is permitted, while feeding of the liquid is maintained. Several positions of the flexible connection 44 for various positions of propeller blade adjustment are indicated in broken lines in Fig. 3.

In operation, the ice-inhibiting liquid, which may be of a mixture of glycerine and alcohol or any other suitable substance, is fed into the annular trough 42 from which the liquid is fed by centrifugal force through the flexible connection 44 into the manifold 33 from which, also by-c'entrifugal force, the liquid is conducted peripherally outwardly through the grooves of the shoe 23. Normally the liquid travels'peripherially outward and is discharged at the ends of the grooves where it spills over, wetting the surface of the mulated upon the blade before the supply of the liquid is turned on, the liquid will be conducted in I Fig. 1 and in Fig. 7A, where the fabric reiniorce-.

ment of the shoeis continued beyond the margins of the shoe and is extended at 45 entirely around the propeller blade. The fabric, preferably rubberized or otherwise coated to present a smooth outer face, is fitted closely to the blade surface and its margins are secured preferably by 'a' secured, and preferably the fabric and shoeare adhered to the blade throughout the contacting area. At its outer periphery the fabric preferably terminates in an oblique edge 41 to minimize the likelihood of developing a vibration node. It will be understood that whichever embodiment is used for a given propeller installation all blades thereof should preferably be protected by similar constructions and that the whole propeller assembly should be dynamically balanced in accordance with the best practice.

In the embodiment of Fig. 9 the distributing shoe 50, instead of having grooves at its surface for conducting the liquid, has continuous passages, 58 extending within the shoe which passages communicate with the surface'of the,

surface of the shoe rather than in the outer surface thereof so that the conducted liquid is in direct contact with the surface of the propeller proper while it is being conducted and when it is released from the passageways. This has the advantage that when the liquid is exposed to the air flow it is already in contact with the material of the propeller surface itself for effectively wetting the same and has less likelihood of being blown off until after it has spread considerably on such surface. In this embodiment the outside grooves 6i, ti, 62, 62, and 63, 63 are curved to terminate in the tapered margins of the shoe to discharge the liquid at the side margins of the shoe While the innermost grooves extend to the tip of the shoe. The outer grooves may be flattened toward such margins and flared as shown in Figs. 10 and 13 without restricting the sectional area of the passage so that discharge and spreading of the fluid along the blade surfaces will be facilitated. Two central passageways 6 l, 66 may extend to the tip of th shoe for distribution of the liquid beyond the end of the shoe.

As shown in Fig. 14 the shoe 6!! is of such shape that it merges with the outline of the propeller blade 65, and the latter may be provided in such a shape that when the shoe 60 is added the outer surface of the composite structure provides the desired aerodynamic characteristics. The shoe 6!! may be secured to the blade surface by adhesion. If desired, additional means may be provided for reinforcing the shoe and for securing it to the blade, for example, a fabric as described in connection with the embodiment for the lefthand blade of Fig. 1. Such a fabric should be embedded in the material of the shoe between the outer surface thereof and the grooves so as not to interfere with the latter, and the side openings in the shoe may be made through such fab- I ric.

In the embodiments of Figs. 15 and 16 provision is made for conducting the liquid'along both faces of the shoe. Fig. 15 shows a shoe 10 in which a series of grooves H, H is provided in the outer surface of the shoe and a series of grooves 12, 12 is provided in the underneath surface of the shoe, this embodiment being a combination of the embodiments of Figs. 1 to 8 and 10 to 14. If it is desired to include the fabric reinforcement in this embodiment the reinforcement may be disposed between the upper and lower sets of grooves so as not to interfere with the flow of the liquid. In Fig. 16 grooves 13, 13 are provided only in the lower surface of a shoe 14 and connection with the outer surface of the shoe is provided by through apertures 15, 15 in the areas desired.

The separately formed shoe of rubber-like ma terial having the liquid conducting passages therein has the advantages of making for greater propeller strength and by leaving it intact, and providing for greater abrasion resistance at the leading edge, but if'desired, the liquid conducting passage may in some cases be provided in the surface of the propeller blade itself, whether the latter be of metal, wood, molded composition, or other material. In Figs. 17 and 18 is illustrated such an application of the invention. A blade has a plurality of grooves 8|, BI, 82, 82, 83, 83, and as, 84 formed in the surface of the leading edge thereof extending outwardly from the root of the blade and terminating at spaced apart positions along the same. A manifold 85 having a flexible connection 86 to a distributing trough, as in the case of the manifold illustrated in Figs. 1 to 4 has an internal manifold space communicating with the several grooves in the blade surface. This manifold may be of molded rubber or other rubher-like material or of metal, wood, orany other suitable material and. may be adhered, strapped or otherwise secured upon the root'of the propeller blade.

Variations may be made without departing from the scope of the invention as it is defined in the following claims.

We claim:

1. Liquid-distributing means for the surface of a propeller blade comprising a cover structure of rubber-like material adapted to be mounted upon the leading edge of the blade with a surface of rubber-like material exposed at said leading edge, said structure having a plurality of liquid-conducting passageways in the material of the cover structure extending along the same and in communication with said exposed surface.

2. Liquid-distributing means for the surface of a propeller blade comprising a cover structure adapted to be mounted upon the leading edge of the blade, said structure having a plurality of liquid-conducting passageways in the material of the cover structure extendingalong the same from a portion thereof nearest the root of the blade when mounted therein, and manifold means at the said portion for feeding liquid into said passageways, said manifold means comprising, a conduit extending transversely of said pas adapted to be mounted upon the leading edge of the blade, said structure having a plurality of liquid conducting grooves extending along the exposed surface of said cover structure.

4. Liquid-distributing means for the surface of a propeller blade comprising a cover structure adapted to be mounted upon the leading edge of the blade, said structure having a plurality of liquid conducting grooves extending along the exposed surface of said cover structure and terminating at spaced-apart positions along said surface.

5. Liquid-distributing means for the surface of a propeller blade comprising a cover structure of rubber-like material adapted to be mounted upon the leading edge of the blade with a surface of said rubberlike material exposed at said leading edge, said structure having a plurality of individual conducting passages beneath the surface thereof extending along. the same and communicating with the exposed surface of said structure at spaced-apart positions along the same.

6. Liquid-distributing means for the surface of a propeller blade comprising a cover structure adapted to be mounted upon the leading edge of the blade with its margins intermediate the leading and trailing edges, of the blade, said structure having at least one liquid conducting passageway beneath the surface thereof in the material of the cover structure extending along the same and open unrestrictedly at the margin of said cover structure.

'7. Liquid-distributing means for the surface of a propeller blade comprising a cover structure adapted to be mounted upon the leading edge of the blade, said structure having at least one liquid conducting groove in the underneath surface of the cover structure extending along the same from its root portion and communicating with the surface of said structure at its margin to conduit the liquid along the groove in contact with the propeller blade and release the ture connecting said groove with 'the outer surface thereof.

9. A protective covering for a blade of a propeller comprising a body of rubber-like material adapted to be adhered to the blade at the leading edge thereof, said body being contoured to provide its outer exposed surface as the aerodynamic surface of the leading edge, and at least oneliquid-conducting groove in said outer exposed surface of the rubber-like material.

10. A protective covering for a blade of a pro-' peller comprising a body of rubber-like material adapted to be adhered to the blade at the leading edge thereof with a surface of the rubberlike material exposed at the leading edge of the blade, said body having at least one liquid conducting passage in the rubber-like material of said body extending along the same from a portion thereof nearest the root of the blade when mounted thereon adapted to receive liquid at said portion and to distribute the liquid upon the blade at a position peripherally outward from said portion.

11. A protective covering for a blade of a propeller comprising a body of rubber-like material, passage means in the material of said body for conducting liquid from a portion of said body nearest the root of the blade when mounted thereon to a position peripherally spaced therefrom and combined strap and manifold means adapted to extend about the propeller blade at its root portion for securing saidbody to the blade and feeding liquid to said passage means.

12. A protective covering for a blade of a propeller comprising a body'of rubber-like material,

passage means in the material of said body for conducting liquid from a portion of said body nearest the root of the blade when mounted thereon to a position peripherally spaced there from, means adapted to extend about the propeller blade for securing said body to the blade,

and manifold means at said portion of said body I for conducting liquid to said passage means, said manifold means comprising a conduit extending transversely of said passageways and in communication with the passageways.

13. A protective covering for a blade of a propeller comprising a body of rubber-like material extending along the blade at the leading edge thereof and having margins disposed intermediate the leading and trailing edges of the blade, and means comprising a strap secured to said body at the root portion and extending around the trailing edge of the blade for securing said body to the blade.

14. In an airplane propeller construction, a propeller blade comprising a propeller body of one material having the general shape and contour of the desired propeller air foil, a layer of surface material upon at least the leading edge of said propeller, the contour of the surface of which layer completes the desired air foil contour of the finished blade, and a plurality of grooves formed in said layer material and extending different distances longitudinally along said blade from the hub end thereof.

15. In a propeller construction, a blade comprising a blade body having a desired air foil contour, a plurality of anti-icing-liquid conduits extending longitudinally of said blade and terminating at different distances along the leading edge of said blade spaced from the hub end thereof for uniformly distributing anti-icing liquid along said blade.

v 16. In a propeller construction, a blade comprising a blade body having a desired air foil contour, a layer of surface material associated with said blade body and having formed therein a plurality of anti-icing-liquid conduits extending longitudinally of said blade, said conduits terminating at different distances alcng the leading edge of said blade spaced from the hub end thereof for uniformly distributing anti-icingliquid along said blade. l

2,334,118 18. In a propeller construction, a blade structure having a desired airfoil contour and a plurality of anti-icing-liquid conduits extending longitudinally of said blade structure and terminating at difl'erent distances along the leading edge thereof for distributing anti-icing-liquid along said blade structure.

19. In a propeller construction, a blade structure having a desired airfoil contour and a. plurality of anti-icing-liquid grooves extending longitudinally in the surface of said blade structure and terminating at different distances along the leading edge thereof for distributing anti-icing liquid along said blade structure.

JOHN F. MORSE.

MYRON L. TAYLOR.

CERTIFICATE or CORRECTION. Patent No. 2,53h,11 November 9, 1915.

JOHN F. HORSE, ET AL.

It is hereby certified that error appears in the printed specification or the above numbered patent requiring correction as follows; Page 1, first column, line 21+, for "to prevent read or preventing-; page 2, first column, line 18, for such a manner that" read --such a manner that a-;

page LL, first column, line 19, claim 5, for "passages beneath read passages in the material of the, cover structure beneath; and that the said Letters Patent should be read'with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day of February, A. D. 19%.

Henry Van Arsdale, (Seal) Acting Commission-= of Patents-

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