US2240310A - Airfoil - Google Patents

Description

H. M. MCKAY April 29, V1941.

Anwen.

Filed oct. '14. Y1939 4 Sheets-sheet 1 ORNEY F IG. 8.

INVENTOR HARRY M. MVcKAY April 29,` 1941.

H. M. McKAY AIRFOIL Filed oct. 14, 1959 4 Sheets-Sheet 2 FIG.LO.

INVE NTOR HARRY M. McKAY April 29, 1941.. H, M, MCKAY l 240,310

AIRFQIL Filed oct. 14, 1959 4 sheets-sneet's FIGL15. F|G.16.

l. l: A!

y INVENTOR.' HARRY M. McKAY TORNEY Awa 2Q, im .i v H MMCKAY 2,240,310

v AIRFOIL Filed oct 14Q 1959 v4 sheets-sheet 4 INVENTOR HARRY MMCKAY lBY@OK`4,.

A ORNEY Patented Apr. 29,1941

AIRFOIL Harry M. McKay, Ferguson, Mo., assignor to St.

A-Louis Aircraft Corporation, St. Louis, Mo., ay

corporation of Missouri Y Application October 14,1939, Serial No. 299,416

- s claims. (c1. 244-123) This invention relates generally toairplanes. More particularly, this invention relates to Va certain new and useful improvement in airplane wings or so-called airfoils and has, briefly stated,- for its chief objects the provision of an airfoil which is so uniquely constructed of co-operable readily joined and connectedvparts that its production and fabrication may be accomplished and effected speedily as to time and economically as to labor and material and which hassuch a unique frame of obliquely disposedtcells that, while light in weight, structurally has form, strength, and durability capable of successfully, and without deformation or loss of normal shape, resisting and withstanding great strains and stresses.

And with the above and other objects in view, my invention resides in the novel 'features of form, construction, arrangement, and combination of parts presently described and pointed out-l in the claims.

In the accompanying drawings (4 sheets) Figure 1 is a plan view, partly broken away and in section, of an airplane wing or airfoil constructed in accordance with and embodying the' present invention:

Figures 2, 3, and 4 are detail sectional views of the airfoil, taken, respectively, along the lines 2 2, 3 3, and 4 4, Figure 1; A

Figure 5 is an enlarged detail sectional view o the airfoil, taken approximately along the line 5 5, Figure 2, illustrating particularly a connection between the airfoil and the fuselage;

Figure 6 is aview similar to Figure. 1 of a slightly modified airfoilembodying my present invention;

Figures 'I and 8 are detail sectional views, taken approximately along the lines 1 1 and 1 8, Figure 6, respectively;

Figure 9 is a detail sectional viewof the modified airfoil of Figure 6, taken' approximately along the line 9 9, Figure 7, illustrating a connection between such airfoil and the fuselage;

Figure 101s an enlarged fragmentary perspective view of the airfoil structure, showing the interlacing and cell-forming connection between ribs of the airfoil, the skin being omitted; Figure 11 is an enlarged diagrammatic perspective view of a companion paiil of the airfoil ribs, illustrating the facile assembling thereof in the formation of thevcellular skeleton or frame-A work of the airfoil;

Figures 12 and 13 arev enlarged fragmentary annular lateral rib-stiflening ange 4.

tail the cell-forming interconnection between some of the ribs and the-skin of the airfoil;

Figure 14 is a detail sectional view of the airfoil, taken approximatelyalong the line Il il,

Figure 12; Figure 15 is a fragmentary plan view illustrating a modied type of fuselage and wing or air l foil attachment;

. Figure 16 is a detail sectional view, taken approximately along the line iG-IS, Figure 15;-

' Figure 17 is an enlarged fragmentary longitudinal sectional view of the airfoil, illustrating the facile provision in the Wing ofgasoline or other.

fuel tanks or containers; i

Figure 18 is a detail sectional view, taken approximatelyalong the line iB iii, Figure 17; and

Figures 19 to 25, both inclusive, are fragmentary plan views of modified types of ribs -and their interconnection in the cellular formation of an airfoil of my present invention.

' Referring now in more detail and by reference characters to the drawings, the wing or airfoil is of so-called geodetic construction and includes a skeleton body or framework A of what maybe de-v scribed. as of honeycom or cell structure formed of a plurality of criss-crossed or intersecting and mutually interlocking or interconnected ribs a, each of which is of unique shape particularly adapted anddesigned foritsv respective location in the entire wing structure, that is to say, the peripheral or marginal contour of each rib a conforms exactly to the curve or con# tour of theparticular wing-section along which it is disposed. l

As best seen by reference to Figures 10 and 1l,

Y. each rib a is stamped or otherwise formed prefer-l ably from relatively thin gauge duralumin or .pther'suitable metallic plate or sheet material includes a web l provided substantially throughut'itsfperiphery, except at what may be v called its trailing end I', with a skin-supporting or'marginal lateral flange comprising aniupper portion 2, a lower portion 2', and a connecting or arcuate nose-portion 2", the web i of each rib a transverse width of the flange and each commun.

icating with a respective kerf 6 extending, as it sectional views of the airfoil, illustrating in de- 55 may be said and with reference particularlyJto Figure 11, vertically for a substantial distance upwardly into, and having a width substantially equal to the thickness of, the web I.

Similarly, certain other or companion ribs a i are provided along'their upper flanged-portions an aligningly apertured fiber or other suitable washer I1, and disposed at the outer longitudinal end vof the wing, is a tipmember D, which may be of any conventional pattern or design, and which is provided along its inner margin with an extension-flap Ilfoverlying the outer marginal portion `of the wing skin B and fixed thereto. as by means of suitable screw-members Il' threadedly engaged with the lugs nr and washers I1, all a's best shown in Figure 4.

'Ihe modiiied wing or airfoil shown in Figure 6 comprises a cellular frame A', which includes 5 of the one rib a. will seat and be disposed with surface evenness or smoothness in the slot 5' of the companion rib a.

The several ribs a, assembled and intersectingly lnterengaged at the slots 5, 5', and kerfs 8, 8', as described, are fixed together at their respective `iuncture points by suitable connection-angles 1. which are conventionally riveted in place in the formation thus of a multiple-sectional or geodetic cellular framework A.

'I'he several so rigidly interengaged and connected ribs a constituting the framework A are obliquely disposed to the longitudinal axis of the finished airfoil and hence likewise for strain and stress resistance obliquely disposed to the line of night of the airplane, and at their rear margin I', the flange-portions 2, 2', of the several ribs a are obliquely cut-away for eiiicient abutment against and connection to a longitudinally extending girder or spar a' provided at regularly spaced intervals along its length with laterally presented marginal flanges 8 for permanent connection to the flanges 2, 2', of the ribs a primarily for equilibrating any unabsorbed torque or twisting forces.' And suitably Isecured to the rearwardly presented face of the rib or' spa'r a', is a plurality of transversely disposed channel-shaped ribs a.2 spaced longitudinally of. the wing and ofmore or less conventional design and shape to provide the trailing edge of the airfoil. all as best seen in Figures 1 and 13.

The obliquely cellular skeleton or framework A is then covered by and enclosed within a socalled fskin B, which extends from a point, as at b, a short distance inwardly from the leading edge of the airfoil, around the leading edge and rearwardly across the upper face, and finally around and underneath the trailing edge, terminating at a point. as at b', a short distance forwardly from such trailing edge, the remaining underface of the airfoil being covered by a sheet or section 9 of relatively inexpensive` fabric material; which may be readily removed and replaced for permitting convenient access to the framework A for repairs and the like, the skin B being by suitable rivets or the like permanently iixed to and iiatwise upon the marginal flanges 'I ofthe enclosedframework A.

a plurality of intersecting and interconnected rib-members a3 substantially similar in form and structure to the ribs a, except that the several ribs a3 are so designed and shaped as to extend entirely across the width and throughout the length of the wing in the provision of a completely-geodetic structure and thereby eliminate the incorporation therewith of the additional conventional elements designed to provide a trailing edge and wing tip, such as the ribs a2 and tip D.

.As illustrated, the modified frame A is provided with a skin B' and an underface fabric 9' substantially in the manner described in connection with the frame A and, in the present instance, is fixed to the fuselage C 'in so-called low wing position by a plurality of pairs of opposed V-shaped angles I9 conventionally riveted to the adjacent ends of the ribs a3. the skin B and. underface fabric 9' being also secured against the fuselage C by means of pairs of angle strips 20. 2|, all as best seen in Figures 'l and 9.

It has also been found that Wings or airfoils constructed in accordance -with and embodying my present invention may be very conveniently fixed to the fuselage C by means of a plurality -iangle strips 24;- all as best seen in Figures 15 and 16.

As shown in Figures 17 and 18, a section of the frame A or A may be blocked off in the formation of a gasoline tank or container by welding or otherwise hermetically sealing certain selected cut-outs 3 with metallic disks 25 and by hermetically sealing a section of the wing skin B or B'cver the top and bottom of the blocked area.` The particular lightening cut-outs 3 located within such blocked area may, of course,

'I'he airfoil A islfinnly secured to the fuselage C by means preferably of a plurality of conventional opposed angles Il, which are riveted to the abutting ends .of the ribs a and. in turn, secured to the fuselage framework II by conventional` mounting angles I2, as best seen inFigures 1, 2, and 5. i.

Lugs or so-called nuts n having lateral flanges I2 are fixed. as by means of rivets Il, to the skin B at spaced points adjacent its outermargin, each lug or nut n being centrally provided with a longitudinal bore I5 opening into a diametrally enlarged recess I8 spaced inwardly a short distance from the `end of the bore I5 for housing be left unobstructed to permit free communication between the component parts of the tank,

and the skin of "the tank having conventional formation as described, a plurality of so-called longitudinally zig-zag ory corrugated ribs e having marginal anges 28 cut-away to provide engagement corners 21 and socket corners 22 may be employed in the formation of the cellular framework of the airfoil. In/.the construction of such a wing, a plurality'of the ribs e may be brought into co-operative engagement, the corner portions 21 of one rib being arranged abuttingly within the socket-corners 28 of the next adjacent rib and being secured together by a plurality of conventionally riveted angle strips 29, as shown in Figures 19 and 20.

If desired, the "zig-zag ribs e' may be provided with straight intermediate abutment s ections 30 having registering rivet-receiving apertures, which may be-secured together in wing formation substantially as shown in Figures 21 and 22. Zig-zag ribs, such as e or e', may be -peripherally contoured for longitudinal disposition within the airfoil or maybe similarly contoured for transverse disposition, as shown in Figure 23. l A

If also desired, a plurality of box-shaped or rectangular ribs g provided with a-plurality -of skin-supporting marginal flanges 3l and formed at their four corners with vertical flattened abutment sections 32 may be employed, as best seen in Figure 24. v l

Likewise a plurality of short rib sections h may be employed, each section h' having top and bottom lateral skin-supporting flanges 33 and at vits opposite outer ends having lateral web extensions providing attachment flanges 34, a plurality of such sections h being assembled and riveted together, substantially as shown in Figure 25. Obviously these latter modications are -substantially each rib is of a different length, the

cells of the wing decreasing toward the tip.

In such wings or airfoils, it may also be stated several parts of the airfoil may be made and thisforce to additional ribs, and so on until the load isevenly resisted by the whole struclture. This-inter-action characteristic enables the wing to still resist failure 'even when damaged.' This characteristic is of great value in military airplanes, where a wing may be called on to operate satisfactorily even though damaged 1 considerably by bullet holes and tears.

Further, the wing is of exceptional structural rigidity, since all forces imposedupon the leading edge, for instance, regardless of angle of incidence, will nevertheless be distributed in compression throughout theskeleton or framework and ultimately transmitted to the fuselage, and any torque-producing forces or shear stresses which might have a buckling or collapsing eiIect on the cells would be equilibrated across either one or the other cell-diagonal by placing the Askin in tension. In fact. by considering the skin as tension-filaments across the cell-diagonals. it will be' evident that the present geodetic wing is a so-called determinant structure, that isto say, a structure for which a-complete and precise stress diagram can be prepared.

And the described gas-tank formation also be made watertight in the provision of an emergency flotation chamber, such as is often `changes and modifications in the form.' construction, arrangement, and combination of thel substituted for those herein shown and described without departing from the nature and principle of my invention. l

that the same structure which acts to hold the Y wing shape or contour serves also to transmit any imposed loads to the body of the airplane without the intervention of a secondary structure of beams, spars, and the like.y The fact that the wing uses a rib which is continuous from top to bottom surfaces and from nose to the rear closing channel prevents the squashing or attening of the wing contour.

Further.. the structure is such that-production costs are very low, since the wing employs only two basic ribs, as shown. Such ribs, being continuous members, may be cheaply and quickly formed by only two dies, and the inherent simplicity of the mating construction makes feasiblev the facile assembly of the wing skeleton by unv trained labor. l

Another great advantage of my wing construction is its'ability to withstand abuse without seriously impairing its strength. A load ap. plied at a random point on any one rib is transmitted to a multiplicity of other load resisting elements. For instance,` in the wing section shown in either Figure 1 or Figure 6, if one imagines a load applied at a random point on any rib in the central portion of the wing, it becomes evident that this force is further distributed to other ribs, which, in turn, distribute vthe airfoil in the plane of such rib and being Having thus described my invention, what I claim and desire to .secure byl Letters Patent is..

1. An airfoil including a frame' comprising, a plurality of straight interlocking ribs having a width substantially equivalent tothe thickness of the airfoil, said ribs being obliquely disposed to the leading edge of the airfoil and connected with each other in criss-cross cell formation, each of said ribs further having a peripheral contour conforming to the sectional contour ofv the airfoil in the planeof such rib.

2. An airfoil including a' frame comprising, a f plurality of straight ribs having a width substantially equivalent to the thickness of the-air- `foil, said ribs being obliquely disposed to the A leading edge of the airfoil, said ribs further beingkerfed at regular intervals forv interlocking engagement in criss-cross cell formation, each of the airfoil, said ribsy being obliquely disposed to the leading edge of the air'foil and connected with each other in criss-cross'cell formation. each of said ribs' further having a peripheral contour conforming to the sectional contour of provided with a latterly projecting marginal iiange forsupporting attachment to the skin ofthe airfoil. q

HARRY M; Melgar, 'c

Images