US1631259A - Variable lift-variable resistance aerofoil - Google Patents

Description

7 1,6 1 June 7, 1927. w. L Gil-MORE- 3 259 VARIABLE LIFT VARIABLE RESISTANCE AEROFOIL Filed Dec. 27' 1920 4 Sheets-Sheet 1 ah'uewkoi Wmu/m LGnmom: I I 391;; SHOT/M04 June 7, 1927' w, GILMORE VARIABLE LIFT VARIABLE RESISTANCE AEROFOIL 4 Sheets-Sheet 2 Filed Dec. 27. 1920 June w. L. GILMORE VARIABLE LIFT VARIABLE RESISTANCE AEROFOIL Filed Dec. 27 4 Shoots-Sheet 3 awve/wloz WILLIAM LEtLMOEE. 33%;; 61mm,

June 7, 1927. w. L- GILMORE 1,631,259

VARIABLE LIFT VARIABLE RESISTANCE AERDFQIL Filed Dec. 27' 4 Sheets-Spam 4 ammo;

' WILLIAM LGnmoizE 3&1 Qt/tonne v I Patented June 7, 1927.

UNITED STATES 'FPATENT OFFICE.

WILLIAM L. GILMORE. 01' PORT WASHINGTON NEW YORK, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO CURTISS AEROPLANE AND MOTOR COMPANY, ma, 0] GARDEN CITY, NEW YORK, A CORPORATION OF NEW YORK.

VARIABLE LIFT-VARIABLE RESISTANCE AEROIOIL.

Application filed December 27, 1920. Serial No. 488,081.

My invention relates to aerofoil surfaces for airplanes and is more particularly concerned with aerofoils havin variablev liftvariable resistance characterlstics, the variation in lift-resistance ratio being brought about through adjustment of the nose porti'on of the aerofoil as distinguished from camber adjustment or incidence alteration as practised heretofore.

The principal objection to variable camher and variable incidence aerofoils is that such aerofoils (and especially supporting surfaces) are complex, costly, heavy and incapable of .being adequately rigidly braced. Though eflicient aerodynamically, structurally such aerofoils are impractical, due principally to the fact that deformation is required on the one hand and body adjustment stallation of any conventional rigid bracing landing and high speed for fli ht is re-- q'uircd. An airplane equipped wit variable liftvariable resistance supporting surfaces can be designed for both-heavy duty and high speed work. As an example of its utility when thus designed, such a machine can be loaded with bombs or other projec tiles, its wings or supporting surfaces being.

adjusted to give maximum lift, and after discharging 1ts load, can be immediately converted. into a high speed, low resistance machine by a reverse adjustment of its wings; its wings when reversely adjusted, though giving less lift, offer greatly reduced resistance in flight.

A further object of the invention is to provide operating mechanism for adjusting the nose of the'aerofoil or aerofoils which is ada ted to be entirely enclosed within the con mes thereof and to be operated manually from a convenient point inside the fuselage or body.

Otherobjects and advantages will be mentioned hereinafter. The sco e of the invention, however, is set forth fully in the claims.

Of the drawings:

F'g. 1 isa transverse vertical section of the nose of an aerofoil,i. e., an airplane wing or supporting surface showing the adjustable nose portlon in a position offering minimum resistance though decreased lift;

Fig. 2 is a similar view showing the nose portion adjusted to offer increased resistance and maximum lift;

Fig. 3 is a fragmentary front end elevation of an airplane illustrating the manner in which the operating mechanism for adjusting the nose portion of the aerofoil is extended into the fuselage or body;

Fig. 4 is an end view of an aerofoil, i. e. an airplane wing or supporting surface showing the relation of the adjustable nose to the rigid body ortion of the wing;

Fi 5 is an enlarged fragmentary perspective view showing a preferred wing construction; the adjustable nose portion formin a part thereof, having been removed;

ig. 6 is a similar view of one of the adjustable nose sections;

Fig. 7 is a detail sectional view showing the manner in which adjacent nose sections are supported;

Fig. 8 is a view similar to Fig. 2 illustrating a modification, the dotted lines indicating the shape ofthe nose portion of the wing when adjusted to offer minimum resistance and decreased lift; 1

Fig. 9 is a view similar to- Fig. 5 illustratwin ing the operating mechanism forming a part prf the modified construction illustrated in Fig. 10 is a detail perspective view of a part of the operating mechanism illustrated in. Fig. 8;

FFig. 11 is a section on the line 1111 of Fig. 12 is a View similar to Fig. 2 illus trating a further modification, the dotted lines as in Fig. 8. indicating the shape of the nose of the wing when adjusted to offer minimum resistance and decreased lift; and Fig. 13 is a perspective view of the operating mechanism illustrated in Fig. 12.

In the embodiment of the. invention se-' lected for illustration an airplane wing or supporting surface is shown. The invention, however, is applicable to aerofoils generally and can be used to advantage in connection with the stabilizing surfaces of an airplane as well as with the stabilizing surfaces of a lighter than air machine.

In Fig. 4 of the drawings. the construction of the variable nose portion and its relative arrangement to the body of the wing is such as to convert what is known in the art as a 32 wing into a C 48" wing, the former being designed for high lift, having a lift coelficient of .0044, whereas the latter is designed for high speed, its lift co-eflicient being .003. The specific Wing designs referred to. however, are merely illustrative. Obviously slight variations in the shape of the adjustable nose portion and slight variations in its placement relatively to the wing body would produce other wing forms having different though similar, aerodynamic characteristics.

The body of the wing is designated generally as 20. The details of its construction are lmmaterial. It may be either entirely internally braced or braced exterior-1y, though in Fig. 4 a wing of the former class is shown. The wing beams of the wing, of which there are three. are designated respectively as 21, 22 and 23. Preferably, the

from the front wing beam 21 backwar ly to its trailing edge is rigid throughout and incapable of intentional deforn'iation. Thus constructed, bracing of more or less conventional arrangement to truss the wing can be utilized.

In addition to the beams 21, '22 and 23, the wing framework includes a plurality of ribs 24, cap strips 25 and covering 26. the latter enclosing the framework in its entirety, and throughout the length of the Wing, adjacent to its leading edge, being extended forwardly to under-lie or over-lie (as the case may be) the variable nose portion herein designated generally as 27. The ribs 24 are also extended beyond the front wing beam 21 and at their forward ends are preferably shaped to conform to the shape of the nose of the wing when accorded its low resistance profile. In Fig. 2 of the drawings, a dotted line indicates the shape of the ribs at their forward ends which it Will be noted, corresponds exactly with the shape of the nose of the wing illustrated in Fig. 1. By thus extending the ribs, strength is provided adjacent to the leading edge of the wing and provision made for the support of the variable nose portion 27 in a manner hereinafter more fully explained.

As a matter of more or less common knowledge obtained through wind tunnel tests, the aerodynamic characteristics of an airplane Wing are governed largely by the shape of the nose of the wing and the location of its leading edge. By raising the leading edge of the wing its lift value is decreased somewhat and its resistance proportionatelv minimized. Accordingly in converting a high lift high resistance wing into a low lift high speed wing it follows naturally that the leading edge should be lowered to obtain the former characteristics and raised to obtain the latter. Though not essential. it is preferred that in converting an airplane wing in the manner indicated that its nose or entering portion be made relatively blunt where low resistance is desired and relatively sharp where high lift is required. In this connection particular attention is directed to Figs. 1 and 2 on the one hand and Fig. 8 on the other. Fig. 12 illustrates a Variable nose construction in which the leading edge of the Wing is sharp in each of its several a'djustments.

The angle of incidence of an airplane is that angle between the horizontal and a straight line passing through or bisecting its leading and trailing edges. Moreover, relatively thick wings, even. though the incidence angle is small, possess a high li't't value, especially wherethe leading edge of such wings is relatively low and comparatively sharp. \Vhere the leading edge of such wings is rounded off and slightly raised, the wing, though thick, nevertheless possesses a low lift value, its resistance. however, proportionately dropping oil". 1t

will be seen. therefore. that in convert ng a thickwing' from a high lift to a low resistance profile, it is desirable that its profile bechanged from a sharp to a relatively blunt leading edge. a

The nose portion 27 of the wing illustrated inFigs. 1 to 7 inclusive is preferably made up of ali ned nose piece sections 28, the shape of w iich in cross section is determined largely by the desired profile of the wing. Each plates 29 -29, a cover plate 30 joining the nose piece section 28 includes endend plates 29 and a cover plate 31, likewise 32 is extended longitudinally of the wing throughout its full length, bracing 33 for the shaft being provided. and an individual tit) eral ribs.

' the shaft 32.

hearing being carried by each of the sev- Thus arranged. the corresponding end plates 29 of adjacent nose piece sections lie closely adjacent opposite faces of the ribs (see Fig. I).

In Fig. 3. it will be noted that the wing illustrated projects laterally out. from the side of the fuselage or body of the air lane of which such wing forms a part. Vith the wings thus arranged. it is possible to extend the shaft 32 upon which the nose piece sections are mounted directly into the fuselage or body in order that theshaft may be turned from within the body by means of suitable operating mechanism designated generally as 34. The operating mechanism illustrated (see Fig. 3.) includes a supporting bracket 45, worm gear 36, worm 37 and operating lever 38. To adjust the nose portion it is but necessary to operate the lever 38 and by such operation rotate Preferably the lever 38 is l cated in convenient proximity to the seat (not shown) provided for the pilot.

Both cover plates 30 and 31 of each of the several nose pieces 28 function, according to the adjustment of the nose portion, as a part of the outer wing covering. In Fig. 1. it will be noted that the cover plate 31 is positioned to outline the leading edge of the wing. whereas in Fig. 2, a portion of the cover plate 31 is enclosed within the wing confines and forms no part whatsoever of the outer wing covering. The cover plate 30. in the low resistance adjustment of the wing forms no part of the wing covering. In the adjustment provided for high lift, however. the cover plates 30 form that part of the under wing covering adjacent to its leading edge. It is by simply rotating the sections 28 which collectively constitute the adjustable nose that the shape or profile of the wing is varied. In one position, the line marking thejuncture of the cover plates 30 and 31 defines the leading edge of the wing whereas in a different adjustment it is the rounded portion of the cover plates 31 only which define the leading edge. More as a guide than anything else. though it adds somewhat to the strength of the wing, arcuate cover plates 39 are provided between adjacent ribs, each late being shaped in cross section to define t 1e path of movement of the inner edge of the cover plates 30 of the several nose piece sections. 7

Referring next to Figs. 8 to 11 inclusive, it. will benoted that a change in the wing profile is obtained in asomewhatsimilar though structurally different manner. As in that form illustrated as preferred. an operating shaft 40 is provided to extend longitudinally throughout the full length of the wing. Upon this shaft a plurality of rigid arms 41 are secured. These arms depend, two between each of the several adjacent wing ribs and carry at. their free ends angle arms 42. the angle arms being i-vot-ed as indicated at 43 for movement re atively to therigid arms 41. The covering of the wing adjacent to the nose is formed of suitable flexible material. thin sheet steel preferred. Such covering designated as 44 is fastened to a stringer 45 extending longitudinally of the wing and is adapted to bebent into either of the two positions indicated in Fig. 8, one

of the positions being indicated in dotted.

lines and the other in fall. In the full line posit-ion. the pivoted angular levers 42 of the operating mechanism shape the covering 44 to define a more or less sharp entering edge. whereas in the dotted line position the covering is allowed to bend freely. since the operating mechanism is retracted. Being allowed to bend freelyand naturally a blunt entering edge as distinguished from a sharp entering edge isdefined.

As a covering for the under surface of the wing adjacent to its leading edge. material similar to the covering material 44 is used. This under covering 46 is pivotallv fastened at its forward edge to one edge of the cover plate 44 and at its rearward edge is arranged to under lie the fixed covering 47 provided for the framework of the wing. Said under covering 46 is adapted to slide freely beneath the fixed covering 47 and as the adjustable nose is operated the covering 46 is retracted and projected. The. mechanism for rotating the shaft 40 may be the same as that provided for operating the shaft 32. In

this modification also the adjustable nose may be made up of a plurality of aligned sections as in the preferred nose construction.

fication illustrated in Figs. 12 and 13, it will be noted, that here again an operating shaft 5-0 adapted to be operated in the same manner as the shafts 32 and 40 is provided.

Coming now to a descri tion of the modi- From the. shaft 50. arms 51 extend. To the .high lift or a low resistance wing as desired.

In each of the three forms of variable nose construction, the wing covering 36 terminates short of the leading edge of the wing, the outline or profile of the wing at the leading ed e being defined by the covering for the ad ustable nose. In each form also a portion at least of the adjustable nose covering in one or the other of its adjusted positions is extended beneath the rigid covering of the wing and when thus extended forms no part whatsoever of the effective wing covering. Moreover, a characteristic common to the three forms of variable nose is the raising and-lowering of the leading edge by adjustment of the nose portion only,

for in each instance, the body of the wing, aft of the front wing beam, is absolutely rigid and incapable-of deformation. In the modification illustrated in Figs. 12 and 13 stops 56' are provided to limit adjustment. of the variable nose portion 54 in one direction.

\Vhile I have described my invention in detail in its present preferred embodiment, it .will be obvious to those skilled in the art after understanding my invention, that various changes and modifications may be made therein without departing from the spirit or scope thereof. I aim in the appended claims to cover all such modifications and changes.

'hat is claimed is:

I 1. In an aerofoil, a fixed nose portion having an opening extending longitudinally of its length in the vicinity of its leading edge, an adjustable nose portion arranged to occupy the space defined by said opening, said adjustable nose portion having a fixed pivot axis extending longitudinally of its length, and means operable to vary the aerodynamic characteristics of the through movement of said adjustable nose portion about its pivot axis. I

'2. In an aerofoil, a fixed nose portion having an opening extending longitudinally of its length in proximity to its leading edge. an adjustable nose portion arranged to occupy and to provide an outer covering for the space defined by said opening, said adjustable nose portion having a fixed pivot axis extending longitudinally of its length and means operable to vary the aerodynamic characteristics of the aerofoil through moveaerofoil ment of said adjustable nose portion about its pivot axis relatively'to said opening.

3. In an aerofoil, a fixed nose portion having an openin extending longitudinally of its length in t e vicinity of its leadin edge, an adjustable nose portion arrange to occupy the space defined by said opening, said adjustable nose portion having a fixed pivot axis extending longitudinally of its length, a rotatable shaft carried by and within the fixed nose portion and fastened to said adjustable nose portion, said shaft being rotatable to vary the aerodynamic characteristics of the aerofoil through adjustment of said adjustable nose portion about its pivot axis relatively to said open in In an aerofoil, an adjustable nose portion provided with separate surface portions respectively comparatively blunt and comparatively sharp, either of which portions is adapted to be so positioned relatively to the aerofoil as to constitute its leading edge, and means for effecting the desired nose adjustment.

5. In an aerofoil, an adjustable nose portion provided with separate surface portions, respectively comparatively'blunt and comparatively sharp, either of which portions is adapted to be so positioned relatively to the aerofoil as to constitute its leading edge, a fixed nose portion so positioned relatively to said adjustable nose portion as to partly enclose the same in any of its several positions of adjustment, and means for effecting the desired adjustment of said adjustable nose.

6. In an aerofoil,'a fixed-nose portion, an adjustable nose portion carried by said fixed nose portion and rotatable relatively thereto, said adjustable nose portion being provided with separate surface portions respectively comparatively blunt and comparatively sharp, either of which surface portions is adapted to be so positioned relatively to the fixed nose portion and to the aerofoil as to constitute its leading edge, and means for effecting the desired rotation of said adjustable nose.

' 7, In an aerofoil, a fixed nose portion, an adjustable nose portion pivoted for adjustment relatively to said fixed nose portion, the pivot axis of said adjustable nose portion being fixed and enclosed within the confines of said fixed nose portion, and means to extend and retract said adjustable nose portion relatively to said fixed nose portion, the adjustable nose portion, when extended, presenting a relatively low and somewhat extended leading edge, and when retracted, presenting a relatively high and somewhat retracted leading edge.

8. In an aerofoil, a fixed nose portion having an opening extending longitudinally of its length in the vicinity of the leading,

edge of the aeroioil, an adjustable nose portion movable relatively to said fixed nose portion and means operable to move said adjustable nose portion, said adjustable nose portion in one position of adjustment being adapted to extend through said opening to present a relatively low and somewhat extended leading edge and in a different position of adjustment being adapted to extend'through said 0 ning and'to present a relatively high an somewhat retracted leading edge.

In testimony whereof I hereunto aflix my signature.

WILLIAM L. GILMORE.

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