US2167601A - Airfoil - Google Patents

Description

AIRFOIL 4 Sheets-Shea?l 1 W. K. ROSE Filed Jan. 18, 1937 July 25, 1939.

ATTORNEYS W. K. ROSE July 25, 1939.

AIRFOIL 4 shets-sheet 2 Filed Jan. 18, 1957 ATTO: NEYS.

July 25, 1939. w ROSE 2,167,601

AIRFOIL FiledJan. 1S, 1937 4 Sheets-Sheet I5 1N VENTOR` MMU/77 K. ,Que BY WWW *QV-Q ATTORNEYS W. K. ROSE July 25, 1939.

AIRFOIL Filed Jan. 18, 1937 4 Sheets-Sheet 4 Mmm /4 @wm BY ELM/,7 X/Qr-Q ATToRNEYs.

Patentecl July 25, 1939 lUNITED STATES PATENT OFFICE 13 Claims.

This invention relates to airplanes and more particularly to airfoils used in the construction thereof which airfoils are characterized by one or more passageways extending therethrough from the lower surface to the upper surface thereof, sc formed and constructed as to increase the lift and decrease the dra-g of the wing.

The invention deals Imore particularly with an improvement in the form of the passageways generally described and broadly claimed in my U. S. Letters Patent No. 2,077,070, granted April 13, 1937, on my copending application Ser. No. 110,145, filed November 1936, but retains the essential characteristics of the passageways. Briefly, in my said U. S. Letters Patent No. 2,077,-

070, the cross sections of the passageways diminish gradually from the inlet to the outlet thereof and the vanes or blades bounding and defining the passageways are so mounted and placed and their cooperating curved -surfaces so formed that the mean cross-sectional line of the passageways gradually flattens from inlet to o utlet with no appreciable straight line passage for air through the passageways from inlet to outlet. Whereit is desired to increase the lift and decrease the drag the inlet ports on the'lower surface of the airfoil are forward of the outlet ports on the upper surface thereof and the curvature is upward respecting the lower surface of the airfoil. When pressure air flows through the said passageways it is subjected toa gradual change of momentum and a force is developed within the passageways themselves which influences the lift drag ratio of the airfoil. As the resultant force vector is directed upwardly and forwardly and as the air is discharged from the passageways in a rearward direction the lift is increased and the drag decreased. In my said U. S. Letters Patent No. 2,077,070, I have pointed out wherein the force developed in passageways so characterized is analogous to that developed in turbines. For convenience of nomenclature and to avoid descriptive detail of the specification and in certain of the claims hereof, I will hereinafter refer to pas? sageways constructed for operation as just set forth as passageways of the turbine type. Such nomenclature, it is to be understood, is not intended to be limited to the precise form of passageways chosen-for illustration in said U. S.

Letters Patent. (nor to the precise form of passageways herein shown) but as d'efinitive of the passageways broadly described in the said U. S. Letters Patent and in this application. Broadly speaking, such passageways herein extendthrough the airfoil in a general spanwise direction and are therefore designated in the claims as substantially spanwise.

In turbine passageways for airfoils as above set forth, in straight-away ight wherein low angles of attack are employed ranging from substantially 0 to 10 and more particularly within the lower range of these angles of attack, the present invention seeks to reduce the drag below that heretofore possible. In accomplishing this I primarily modifyvthe form of the inlet port 10 of the passageways so that the forward vane or blade projects downwardly beneath the rearward vane or blade and tends to create an eddy current of air to the rear thereof in a forward direction along the under side of the airfoil and to 15 shield the lower portion of the rearward blade from impact. I furthermore preferably extend the curved surface of the rearward vane or blade at the bottom to the rear so that even at the higher angles of attack impact resistance is 20 avoided. In modifying the inlet port of the passageway as just set forth, its essential characteristie shape is not departed from and the increase in lift resulting from its turbine character and the decrease in drag due to the projection of its 25 discharged airstream are retained.

The eddy current induced'by the change in form of the inlet ports of the passageways just referred to, greatly decreases the drag of the airf oil. 'I'he eddy current takes the form of a multi- 30 tude of minute rotatingspirals, the rotation being in a counter-clockwise direction. The result of this is to effect a rolling movement of the air along the, under surface of the airfoil which in large part eliminates the skin friction between 35 that surface and the stream of air passing beneath the airfoil. With the solid airfoil commonly used commercially, such for example as' the Clark Y, at low angles of attack the spiral eddies beneath the wing are barely detectable 40 and have not been consideredl as functional. In fact any function which might be attributed to them is negligible. j I have discovered that the very important function above set forth is present when the eddies are increased in magnitude and number by the improved form of inlet port for the passageways above set forth and this whether or not the passageways be open or closed.

The terms clockwise and counter-clockwise frequently employed herein are to be inter- 50 preted as referring to the direction of motion of the air eddies or mechanical parts to which they are applied when viewed from the left side of the airplane.

In furtherance of the said object of decreasing the drag particularly in the lower angles of attack the present invention incorporates a hinged or pivotally mounted trailing edge section, commonly referred to as a flap, of novel and advantageous design the forward wall of which comprises the rear vane or blade of a turbine passageway constructed in accordance with the present invention. This turbine passageway is located immediately to the front of the trailing edge section or flap and its opening and closing is controlled by the position of the trailing edge section or ap. The ap has a normal position very different from that in the prior art. Its turbine passageway is preferably closed and its upper surface instead of continuing the smooth unbroken curve of the upper camber of the airfoil extends rearwardly therefrom in a plane substantially parallel with the longitudinal axis of the airplane so as to be substantially in line with the flight path on straight-away flight. In this position, therefore, the normal stream of air above the airfoil continues unbroken over the trailing edge section or flap without the formation of trailing edge vortices, and to this extent the drag is reduced. Both in normal position and in its downward position, however, the flap by reason of its said peculiar and novel form, tends to prevent trailing edge vortices above its rear edge. Furthermore in its downward position the flap cooperates with the downwardly extending forward vanes or blades of the passageways in directing pressure air therethrough to increase the lift and decrease the drag of the airfoil.

A further object of the invention in the preferred form thereof in decreasing drag with an airfoil provided with turbine passageways is to design the leading edge of the airfoil in such a way that the top of the nosepiece presents a smooth unbroken surface from its forward margin backward to the maximum ordinate of the top camber curve, to which end the forward passageway of the airfoil should have its outlet port to the rear of said maximum ordinate. Preferably the inlet port of the forward or nosepiece passageway on the lower surface of the airfoil should be to the front of said maximum ordinate.

A further object of the invention is to provide for automatic opening and closing of the turbinev passageways characterized as above and more particularly those in advance of the flap passageway. In attaining this object I preferably though not necessarily combine means for manual opening and closing of the passageways with the means providing for automatic operation thereof.

A further object of the invention where automatic opening and closing of the passageways are provided for is to effect said automatic opening and closing at predetermined angles of attack.

Further objects of the invention will be apparent as this specification proceeds.

I have chosen as a means for illustrating my invention a high wing monoplane equipped with the usual landing gear for taking off and landing on the ground, and for simplicity of showing have illustrated only two passageways in each airfoil, the nosepiece passageway at the front and the ap passageway at the rear. It should be understood, however, that this is purely for convenience of illustration and is not to be considered in any sense as limitative on the scope of this invention either in respect to the type of plane shown or to the number of passageways embodied in the airfoil. The drawings are in large part schematic. In these drawings,-

Figure 1 is a plan of the airplane selected for illustration with the airfoils embodying one form of this invention;

Fig. 2 is a crossl section of the right hand airfoil of Fig. 1, on. an enlarged scale, on the dot and dash line 2--3 of Fig. 1 with the trailing edge section or flap in normal position, the wing tip and aileron being omitted for clearness of showing:

Fig. 3 is a cross section of the right hand airfoil of Fig. l, on an enlarged scale, likewise on the dot and dash line 2--3 except that the trailing edge section or flap is in its downward position, the wing tip and aileron being omitted for clearness of showing:

Fig. 4 is an end view of the right hand airfoil of Fig. 1, on an enlarged scale:

Fig. 5 is a perspective broken away of the right hand airfoil of Fig. 1, on an enlarged scale, illustrating the mounting and operating structure for the nosepiece and trailing edge sections:

Figs. 6 to 9 inclusive, are diagrammatic representations of airfoils illustrating the airflow about the airfoils, Figs. 6 and 7 showing an airfoil of substantially the same dimensions as that of Fig. 1 except of the solid type, and Figs. 8 and 9 showing the airfoil of Fig. 1. Figs. 6 and 8 represent the airflow about the respective airfoils at low angles of attack and Figs. 7 and 9 at higher angles of attack. The airflow lines of Figs. 8 and 9 when compared respectively with those of Figs. 6 and 7, indicate in part the functional effect of the invention herein set forth.

'I'he fuselage I0 of the airplane illustrated has mounted thereon at the top in usual well known manner an airfoil Il at the left side and an airfoil I2 at the right side. Aside from the reversal of the wing parts necessitated by the fact that one wing is to the left and the other to the right of the fuselage, the wings are'of id entical construction and the description of that construction, therefore, can be limited to one wing, the right wing I2, as shown in Fig. 1, being selected for this purpose.

The airfoil I2, as set forth in the preamble hereof, is for convenience of illustration shown as provided only with a forward or nosepiece passageway and a rearward or trailing edge or flap passageway, it being understood that additional passageways such as illustrated in my said U. S. Letters Patent No. 2,077,070, may, if desired, be provided. With only the nosepiece and trailing edge of flap passageways herein shown, the airfoil ls formed with a main supporting section I5, a leading edge section or nosepiece I6, a trailing edge section or nap I'I, an aileron I8, and a wing tip I9.

The main supporting section I5 is hollow and incloses the internal bracing structure of the wing. This bracing structure is preferably built along conventional lines and is schematically illustrated herein as comprising a forward spar 23 and a rearward spar 24 connected with the usual cross bracing 25 and with chordwise panels 26, technically referred to in the art as ribs, provided at suitable intervals, which (except for the spars 23, 24) extend in cross section throughout the inner hollow of the main supporting section of the wing, one of said'panels being at each end of that section.

The leading edge section or nosepiece I6, like the main supporting section I 5, is hollow and incloses its own supporting structure which as illustrated comprises a relatively large metallic tubular spar 30, the outer shell of the nosepiece being carried on that spar by chordwise panels 3| J Pmounted at suitable intervals in 'the nosepiece and extending in cross section (except for the spar 30) throughout the inner hollow of the nosepiece, one of said panels being at each end of the nosepiece.

The trailing edge sction or flap I 1 likewise like the main supporting section I5 is hollow and incloses its own supporting structure which as 1illustrated comprises a metallic tubular spar 34, the outer shell of the trailing edge section or flap being carried on that spar by chordwise panels 35 mounted at suitable intervals in the trailing edge section or flap and extending in cross section` (except for the spar 34) throughout the inner hollow of the trailing edge section or ap, one of said panels being at each end of the trailing edge section or flap.

'I'he aileron I8 is, except as to its preferred upper and lower camber, later to be referred to, of

conventional structure and mounting, and provided with the usual means for manual control, not shown. It is preferably rigged, however, so

that in normal position it lies in line -with the ap I1, when the flap is in'normal position as stated in the preamblehereof and later to be more fully described. As will be readily understood, the front wall of the aileron I8 is semi-circular in cross section and is mounted for rotation about the center in the aileron of thecircle from which the front wall is struck. The front wall with only sufficient clearance abuts against the rear wall of the main supporting section I5 and of the wing tip I9, which rear wall is in cross section of cooperating semi-circular curvature, being the sector of a circle struck from the same center as is the forward curvature of the aileron I8 but with a slightly longer radius to afford the necessary clearance. As this is all of conventional construction no detailed showing of the same is made. It will be apparent from the foregoing that there is preferably no turbine passageway provided betwee'n the aileron I8 and the main supporting section I5 and the wing tip I9.

'I'he wing tip I 8 -may be of any conventional design and structure such as illustrated, and as such is carried by the strutted framework of the main supporting section I5 in a well known manner, no detailed showing of the same being herein made. It should be understood, however, that this invention is not to be considered as limited to the employment of conventional wing tips, and that wing tips of improved design and structure may of course be employed without departure therefrom. Asan example of suchimproved Wing tips reference may be had to my copending application Ser. No. 116,246, filed December '7, 1936, issued as U.v S. Letters Patent No. 2,125,738.

The leading edge section or nosepiece I6 and the trailing -edge section or flap I1 are each rotatably supported in bearings or journals carried respectively on the forward spar 23 and the rearward spar 24 in like manner as in the present practice respecting the mounting of flaps and ailerons, a suitable number of said bearings or journals being provided. One of said bearings or journals 40 is illustrated in the broken away por'- tion of Fig. 5. Reference being had to that bearing or journal, it will be apparent that it projects through the rear wall of the main supporting section I5 and into the interior of the trailing edge section or flap I1 where it carries the tubular spar 34 rotatably mounted therein.

'I'he structural characteristics of the airfoil as above set forth assure great strength of the air-J vidual parts. The rectangular framework of the main supporting section at the root of the wing is furthermore suitable for firm attachment to the structural framework of the fuselage, such that no exterior bracing is required. It will be understood that the forward and rear spars (23, 24) of the main supporting section of the airfoil may if desired be extended at the root of the wing into suitable fuselage framework for cantilever support of the airfoil.

The exterior conformation of the airfoil selected for illustration is, except for the wing tip, best illustrated in Figs. 2 and 3, wherein the characteristic features of the present invention are likewise more particularly shown.

The top camber of the airfoil is, as will well be understood, to be determined from the standpoint of eilciency dependent on the character and type of airfoil selected as best suited for the purpose to which the airplane is primarily designed. 'Ihe top camber shown, therefore, in Figs. 2 and 3 should be understood as merely illustrative and a convenient showing for describing the invention. I do prefer, however, although it is not essential, that the top surfaceV of the trailing edge section or flap I1 be substantially fiat throughout, and as an aid in attaining high angles /of attack that the nosepiece I6 have a pronounced high camber and be ratcher blunt as indicated. 'Ihe lower surface of the nosepiece, as shown more particularly in Figs. 2 and 3, should be formed with a convex camber curve of sufcient chord to give to the impact airstream a substantially definite flow line for the low angles of attack heretofore referred to, such for example as is illustrated in Figs. 8v and 9 later to be more fully described. The contour of the lower surface of the remainder of the wing will be apparent as this description proceeds.

The rear wall of the leading edge section or nosepiece terminates in a curved vane or blade 44 of such curvature as to form the forward vane or blade of a turbine passageway as set forth in the preamble hereof. At the bottom of said vane or blade 44 the curvature extends slightly to the rear as at the reference numeral 45, but this preferably without breaking the smooth contour of the vane or blade, At the bottom of the rearwardly extending curved vane portion 45, the vane or blade unites in a rounded edge with the lower curved surface of the leading edge section or nosepiece I6 which should be given the desired camber, as above indicated, in manner well understood by those'skilled in the art.

I'he forward wall ofthe main supporting section of the airfoil I5 terminates in a vane or blade 48 of such curvature as to form the rearward vane or blade of a turbine passageway as set forth in the preamble hereof, the vanes or blades 44 and 48 cooperating to form the turbine passageway 49. At the bottom of such vane or blade 48, the curvature extends slightly to the rear as at the reference numeral 50, but this preferably without breaking the smooth contour of the vane or blade. tending curved portion 50, the vane or blade merges into the lower surface of the main supporting section I5 which may be given a desired camber, as above indicated, in manner well understood by those skilled in the art. As illustrated, the bottom surface of the main supporting section VI5 is substantially at without any curvature whatsoever other than that at the lower portions of its forward and rear walls.

The rearwardly curved portion 45 of the vane At the bottom of the rearwardly exor blade 44 extends downwardly below the rear- Wardlycurved portion 50 of the vane or blade 48. 'Ihis is graphically illustrated by reference to the dot and dash line B-Con Fig. 2 drawn to continue the lower camber'curve of the nosepiece to the trailing edge of the flap in conventional position (indicated in dotted lines) as the theoretical bottom curve for a wing of semi-symmetrical or convex bottom camber. As a result of this and of the respective curvatures employed 'the eddy current beneath the main supporting section of the airfoilhereinabove referred to and later to be more particularly described, is set up on the flight of the airplane, and impact resistance on the vane or blade 48 at the bottom thereof is prevented.

The mean cross-sectional line of the passageway 49, indicated by the dot and dash line M-M in Fig. 3, comprises the segment of a spiral in like manner as in the preferred form of passageway specically chosen for villustration in my said U. S. Letters Patent No, 2,077,070. As set forth in said Letters Patent the said spiral of which the said mean cross-sectional line is a segment is by preference logarithmic, though is not essentially so, reference being had to said U. S. Letters Patent for a full discussion of this particular feature of my turbine passageway. The rear wall of the main supporting section l5 terminates in a curved vane. or blade 54 of such, curvature as to form the forward vane or blade of a turbine passageway as set forth in the preamble hereof. At the bottom of said vane or blade 54 the curvature extends slightly to the rear as at the reference numeral 55, but this preferably without breaking the smooth contour of the vane or blade. At the bottom of the rearwardly extending curved portion 55, the vane or blade merges into the lower surface of the main supporting section I5. y

The forward wall of the trailing edge section or flap terminates in a vane or blade 58 of such curvature as to form -the rearward vane or blade of a turbine passageway, as set forth in the preamble hereof, the varies or blades 54 and 58 cooperating to form the turbine passageway 59. At the bottom of said vane or blade 58 the curvature extends slightly to the rear as at the reference numeral 6I), but this preferably without breaking the smooth contour of the vane or blade. the bottom of the rearwardly extending `curved portion 60, the vane or blade merges into the lower surface of the trailing edge section or fiap I1 and. forms a continuation of itscamber. The curved portion 55 of the vaneor blade 54 extends downwardly below the rearwardly curved portion B of the vane or blade 58. As a result of this and of the respective .curvatures -employed an eddy current as hereinabove referred to and later to be more particularly described is set up at the rear of the curved portion 55 of the vane or blade 54 on the flight of the airplane with the trailing edge section or flapin normal position, and impact resistance on-the vane or blade 58 at the bottom thereof is prevented, the latter being true in both normal and downward positions of the trailing edge section or flap I1.

I'he mean cross-sectional lineof the passageway 59, indicated by the dot and dash line N-N in Fig. 3 comprises the segment vof a spiral in like manner as hereinabove discussed respecting the mean cross-sectional line M--M of the pasis of novel and advantageous camber. The carnber of the lower surface 65 of the flap is in cross section a long sweeping curve slightly concave in form from the bottom up. This concave under surface merges in front (as above stated) with the rearwardly curved portion 60 ofthe vane or blade 58 at which junction the concave portlon of the camber starts, and it terminates in a long slender point at the rear where it joins the upper at surface of the trailing edge section in a substantial lineal but rounded margin which comprises 4the trailing edge of the trailing edge section or flap.

i It is preferred that the aileron I8 conform in cross-sectional contour with the trailing edge section or flap I'l except as to the forward wall thereof, heretofore described as semi-circular. This contour of the aileron of the airfoil chosen for illustration may be observed in the end view thereof shown in Fig. 4.

With the conventional form of wing tip employed as herein illustrated it is preferred that its upper camber where it joins the main supporting section I5 of the wing and the leading edge section or nosepiece I6 thereof, conform with the upper camber of these two members with the forward passageway 49 closed. It is preferred that the lower camber at its junction with the said main supporting section I5 and the leading edge section or nosepiece I6 not be cut away to the rear of the nosepiece section as in the case of the main supporting section, but that its camber follow the bottom camber of the leading edge section or nosepiece I6 (in closed position of the slot 49) and continue as at the reference numeral 68 with but slight, if any curvature to its junction with the semi-circular rear wall in front of the aileron heretofore described. Such upper and lower camber of the wing tip I9 is graphically illustrated in the end view showing of the wing tip in Fig. 4, wherein the cross-sectional outline of the passageway 49 and of the lower camber of the main supporting section I5 are illustrated in dotted lines.

In view of the identical construction of the right wing I2 and the left .wing II, except for such reversal of parts as is necessitated by the fact that the two wings are on opposite sides of the fuselage, the left wing II of the airplane is not illustrated in the same detail as the right wing, the left wing I I being only specifically illustrated in Fig. 1. To the left wing II in Fig. 1 I have appended to the parts there illustrated the same reference numerals as heretofore employed on the corresponding parts of the right wing I2, except that to these reference numerals I have added a prime (')-this to add to clarity in applying the foregoing description of the right wing I2 to the left wing I I.

Both the forward or nosepiece passageways and the rearward or flap passageways on the right and left Wings, as herein illustrated, are susceptible of being opened and closed at the top thereof and means are provided for controlling the extent to which the said passageways may be opened from a substantially complete closure thereof to a maximum opening in which substantially no air can flow through the passageways from bottom to top in a straight line. I prefer that the opening and closing of the forward or nosepiece passageways in both of the wings be substantially simultaneous and the degree of opening of the two nosepiece passageways be uniform. In like manner I prefer that the opening and closing of the rearward or flap passageways be substantiaily simultaneous and the degree of opening of the two flap passageways be uniform. The opening and closing of the nosepiece passageways need not of necessity,vhowever, be correlated in time and degree with the flap passageways, although as it will later appear in the ordinary operation of the invention, the pilot will in many instances so correlate the opening and closing and the degree of opening of the forward and rear passageways.

The forward or nosepiece passageways have means provided for automatic opening of the same which may be adjusted toa predetermined positive angle of attack and for automatically effecting closure of the passageways lat lesser angles of attack. Both forward and rear passageways have means for manually opening and closing the same at the will of the operator, the parts being so adjusted and arranged as to the forward passageways that the automatic opening and closing of the same is under the control of theoperator should the operator desire to forestall or prevent automatic operation.

To secure a substantially simultaneous opening and closing of the forward or nosepiece passageways and a uniform degree of opening thereof and to place said operation under the control of the pilot, I prefer that the operating mechanism of the two forward or nosepiece passageways be interconnected and under a single controlling device. As illustrated, I have shown a tubular shaft 15, suitably mounted respecting the framework of the fuselage which is in line with the tubular supporting spars 30, 30 of the leading edge sections or nosepieces IB, I6 respectively, which shaft is firmly attached to the said leading edge sections or nosepieces at their respective roots, the attachment preferably being such that the torsional strain of the shaft 15 in rotating the same is transmitted to the said tubular spars 30, 30'. Said connection is schematically illustrated respecting the right wing I2 in Fig. 5, wherein an annular flange 16 surrounding the shaft 15 and securely fastened to the right end thereof is screwed or bolted through the chordwise panel 3|, to a similar flange 11, surrounding the tubular spar 30 and securely fastened to the root end thereof. It will be understood by those skilled in the art that if for structural reasons or otherwise the two tubular spars 30 and 30', are not in alignment, as for example in the event that the two wings are mounted at a positive or negative dihedral angle or are mounted with an angle of sweepback, universal joints (not shown) may be supplied in the shaft 15 to provide for such lack of alignment without loss of synchronism in the opening and closing of the forward or nosepiece passageways.

On the shaft 15 is mounted a crank arm 80, keyed thereto or-otherwise attached so as to prevent relative motion between the shaft and the crank arm. From the outer end of the crank arm 80 there depends a link 8| pivotally attached thereto at the top and at the bottom pivotally attached to the operating-'arm 82 of a bell crank 83 which is pivotally mounted at its angle to suitable framework in the fuselage and has its operated arm 84 at the outer endA thereof pivotally connected with a link 85, the other end of which link 85 is pivotally connected to the bottom of an operating lever 86.

The operating lever 86 is journaled on a suitably supported shaft 81 at a suitable distance from the Apivotal connection of its bottom with the link 85 just referred to. The operating lever has a manually operated spring pressed pawl 88 which cooperates with a ratchet 89 in maintaining the lever 86 and through its train of apparatus just described, the leading edge sections or nosepieces I 6, IB in the position to which 'they are adjusted by the pilot through the said operating lever 86. The operating mechanism of the pawl 88, however, embraces a stud 90 which may manually be moved into and out of locking engagement with a restraining shoulder 9| on the-operating lever 86 and by which when in engagement therewith the pawl 88 is raised against the action of its spring out of contact with the ratchet 89 and maintained in such position until the stud 90 is released by the operator. The mechanical details of said pawl and ratchet construction and operation are so well known to those skilled in the art as to render unnecessary a detailed showing and description thereof.

A two way stop 92 is suitably attached to the fuselage framework for cooperation with the Y crank arm 82 and it is so adjusted in relation thereto that the counter-clockwise rotation of the leading edge sections or nosepieces on opening the forward passageways is arrested when the maximum opening heretofore described is attained, and the clockwise rotation of the leading edge sections or nosepieces arrested when the-said passageways are closed. l

An adjustable spring 93 is provided in the train of operating mechanism for opening and closing the forward passageways heretofore described, here shown as attached between the fuselage framework and the lower end of the link 8|. By properly adjusting the tension of this spring the tension on'the leading edge sections or nosepieces I6, I6 tending to maintain the same in closing position for the forward passageways may b e regulated in such way that the angle of attack at which the forward passageways are automatically opened may be predetermined.

The mechanism herein illustrated as provided for nianually opening and closing the rearward or flap passageways 59, 59 is substantially identical with that heretofore described for opening and closing the forward or nosepiece passageway 49, 49 and a detailed description of its construction and operation is thereof not necessary. It embraces a tubular shaft 95, provided with universal joints (not shown) where necessary, for interconnecting the trailing edge sections or aps I1, l1', flanges 96 and 91 being preferably employed in like manner as .are the flanges 16 and 11; a crank arm |00 rigidly mounted on the shaft 95, and a link |0| pivotally attached to the outer end thereof and to the outer end of the operating arm |02 of a pivotally mounted bell crank |03 the operated arm |04 of which is connected by a link |05 to the lower end of an operating lever |06; said operating lever |06 being suitably journaled on the shaft 81 and carrying a manually operated spring pressed pawl |08 normally maintained in operative contact with a suitably mounted ratchet |09.

As the trailing edge sections or flaps I1, I1 are not herein illustrated as automatically operable, parts corresponding with the stud 90 and its restraining shoulder 9| and the yadjustable spring 93 of the train of operating mechanism for the leading edge sections or nosepieces |6, I6' are not essential in the train of operating mechanism for the trailing edge sections or flaps I1, I1'. However, a two way stop I2 is provided.

As will be observed by comparing Figs. 2 and 3, the opening and-closing movement of the trailing fdge stions or flaps is the reverse of that of the leading edge sectionsv or nosepieces. Thus, to open the forward passageways 49, 49' the leading edge sections or nosepieces are rotated counterclockwise and to close the said passageways, clockwise; while respecting the passageways 59, 59' to open the same the trailing edge sections or flaps are rotated in a clockwise direction and to close the said passageways, in a. counter-clockwise direotion. Furthermore in moving from normal closed position to open position and back to closed position, the trailing edge sections or flaps travel through a far greater arc than do the leading edge sections or nosepieces in their opening and closing movements.

I have found it convenient to reverse the connections of the links 85 and |05 to their respective operating levers 86 and |06, and to employ a shorter leverage in the operating arm 82 of the bell crank 63 than in the operating arm |02 of the bell crank |03 to compensate for this difference in the direction of opening and closing movements of the leading edge sections ornosepieces and the trailing edge sections or flaps and the respective arcs traveled. In this arrangement with the leverage properly proportioned the operating levers 86 and |06 will both be pulled to the rear to open their respectively controlled passageways 49, 49' and 59, 59' and to the front to close said respective passageways. Furthermore, in any aligned position of the operating levers 86 and `|06 their respectively controlled passageways will be opened or closed to the same degree of their opening or closure. This convenient indication to the pilot of opening and closure and the degree thereof respecting the two sets ofpassageways is obviously not to be considered in any way limitative upon the scope of this invention but rather as a mere incident of the operation of the control mechanism selected for illustration as a means for manually controlling the leading edge sections or nosepieces and trailing edge sections or aps and the passageways governed thereby.

In the preamble hereof, it was stated that in the normal position of the trailing edge sections or fiaps (Il, |1) their passageways (59, 59') are closed and their upper surfaces substantially parallel with the longitudinal axis of the airplane so as to be substantially in line with the flight path on straight-away flight. While this language will be readily understood when taken in connection with the airplane here chosen for illustration it may be subject to misinterpretation when the invention is applied to other types of plane, as for example where the Wings are mounted at a dihedral angle. I am not acquainted with any technical phraseology by which this normal position of the trailing edge sections or flaps may be specified in relation to the airfoil itself. In Fig. 2 I have, however, indicated by the dot and dash line C-C the reference chord line of the wing as conventionally drawn, i. e., a straight line joining the leading and trailing edges with the trailing edge section or flap having its upper surface continuing without break the upper camber of the wing. With an airfoil of the upper and lower camber illustrated, the upper surface of the trailing edge section or flap when in normal position will be parallel with said reference chord line as conventionally drawn. It will appear at once to those skilled in the art, however, that this might not be true if the leading edge were raised or lowered 'by change in the forward camber of the leading edge section or nosepiece. Defining the normal position of the upper surface of the trailing edge section or iiap in respect to the reference chord line as conventionally drawn in the claims hereof, should not be construed as specifically limited'to that precise language but should on the contrary be understood in its functional significance and be interpreted in accordance with its functional disclosure herein.

The position of the trailing edge sections or flaps I1, I1' with maximum opening hereinabove dened of the rearward passageways 59, 59', is conventionally indicated in Fig. 3. It is obviously dependent upon the precise form of turbine passageway selected and is accordingly subject to variation as desired. As illustrated, the upper surface of the trailing edge section or flap in its lower position makes a decided angle with the upper surface of the main supporting section, and the under surface of the trailing edge section or flap extends downwardly at a considerable angle to the under surface of the main supporting section.

From a mechanical aspect the automatic opening and closing of the forward or nosepiece passageways 49, 49 is as follows: 'Ihe stud 90 having been engaged with its restraining shoulder 9| and the pawl 88 thus withdrawn from operative contact with the ratchet B9 so that the leading edge sections or nosepieces I6, I6' are free to move within their limits of movement, it will be observed that the leading edge sections or nosepieces are held in their closing position by the adjustable spring 93 and by the predominating weight of the leading edge sections or nosepieces above and to the rear of their axes of rotation. On the flight of the airplane the forward walls of the leading edge sections or nosepieces are subjected to great impact resistance and the air pressure there localized is correspondingly great. The preponderance of this air pressure above or below the leading edge is dependent upon the angle of attack. At the lower angles of attack the balance is above. This gradually diminishes as the angle is increased until atv higher angles the balance is below. As countew balancing the downward air pressure on the upper surface of the leading edge sections `or nosepieces above and to the rear of their axes of rotation there are the upward air pressure on the lower surface of the leading edge sections or nosepieces to the rear of the axes of rotation thereof and the air pressure Within the passageways 49, 49 forward and upward on the nosepiece vanes or blades d5, 45. When on increasing the angle of attack the forces developed by the air prsure on the lower surface of the leading edge sections or nosepieces and in the passageways 49, 49' exceed the forces tending to maintain the said passageways closed, the leading edge sections or nosepieces will rotate counterclockwise and open the passageways. The passageways so opened will remain open until the forces tending to close them exceed those tending to open. them whereupon the leading edge sections or nosepieces will rotate clockwise and automaticallyl close the passageways.

From the foregoing it will be noted that in normal straight-away flight at low angles of attack the forward or nosepiece passageways 49, 49 are automatically closed, and that from this automatically closed position they are automatically opened at a predetermined (by the adjusted tension of the spring 93) higher angle of attack and automatically closed at a lesser angle of attack.

'I'he mechanical opening and closing of the forinduced to decrease the drag of the airfoil.

ward passageways will readily be understood from the foregoing detailed description of the train oi mechanism provided for that purpose. The stud 90 will of course be manually released from its restraining shoulder 9| and with the pawl 88 manually withdrawn from the ratchet 89, the pilot may by the controlling lever 86 move the leading edge sections or nosepieces I6, I6' te the position desired by him within the range of movement hereinabove described and may maintain that position by releasing the pawl 88 for its spring pressed engagement with the ratchet 89.

Likewise it is believed that the manual operation of the trailing edge sections or flaps` I1, I1' and the opening and closing of the rearward passageways 59, 59' willl readily be understood from the foregoing description of the train of mechanism provided for this purpose. The pawl |08 having been manually withdrawn from the ratchet |89, the pilot may be the controlling lever |06 move the trailing edge sections or flaps IT, I1 to the position desired by him within the range of movement hereinabove described and may maintain them in that position by releasing the pawl |08 for its spring pressed engagement with the ratchet |09.

Reference now being had to the airow diagrams Figs. 6 to 9 inclusive, it being understood that the following applies to both the right and left airfoilsy and referring first to Figs'. 6 and 8: It will be observed that in Fig. 8 with the leading edge section or nosepiece I6 in its downward position and the trailing edge section or nap l1 in its normal position with both passageways 49 and 59 closed, there is formed to the rear of the downwardly extending portion of the leading edge section or nosepiece an eddy current which takes the form of a series of spiral rotating eddies comprising as it were a rolling contact between the bottom surface of the main supporting section and the stream of air owing thereunder. This is very substantial as compared with the corresponding inconsequential eddy current shown in Fig. 6 and is purposely will furthermore be observed that the airstream beneath the surface of the airfoil in Fig. 8 does not strike the forward wallof the main supporting section which forms the rearward vane or blade of the passageway 49, so that no impact resistance is encountered thereby and drag is correspondingly reduced.

In Fig. 8 rotating spirals of air are formed to the rear'of the downwardly extended portion of the rear wall of the main supporting section of the airfoil. 'These reduce drag in providing a rolling contact between the lower portion of the forward wall of the trailing edge section or ap I1 and the pressure air beneath, and no impact resistance is encountered by said forward wall which forms the 'rearward vane or blade of the rearwardpassageway 59.

In Fig. 6 it will be seen that the airstream beneath the rear portion of the trailing edge section or ap operating in conjunction with that above the rear portion of the flap produces trailing edge vortices above the flap`which increase drag. In Fig. 8, however, the trailing edge section or flap I1 is raised above the poson of the construction thereof is projected rear.- wardly more in line with the airstream above the trailing edge section or iiap and the two streams of air above and below mingle and tend to prevent the formation of trailing edge vortices.

In comparing the lift and drag features of a conventional airfoil as shown in Fig. 6 with those of an airfoil embodying my invention as shown in Fig. 8, the following is noted: Reference to Figs. 6 and 8 discloses that the airstream below the airfoil in Fig. 8 slopes slightly upward to the rear beneath the trailing edge section or ap, while that in Fig. 6 does not have this upward slope. As above seen the direction of the airstram beneath and to the rear of the trailing edge section is one of the contributing factors in decreasing the drag. This deflection of the airstream below the airfoil slightly upward beneath the trailing edge section or flap results Ain some loss of lift as compared with the showing of Fig. 6. However the decreased drag in Fig. 8 permits increase speed of the airplane with the same expenditure of motor or propulsion power and the lift lost by the slightly upward deflection of the airstream beneath the, trailing edge section or flap is more than recovered by the increased speed. Nor does this increase of permissible speed increase the drag to the same extent las it increases the lift. .The air pressure forces acting on an airfoil increase approximately as the square of the velocity. Under all flying conditions with the airplane in flight the total lift is always more than the total drag. Thus the gain in lift due to the higher velocity alone is always greater`than the gain in drag resulting from the saidhigher velocity.

For straight-away iiight within the lower angles of attack it is recommended that the -trailing edge sections or flaps I1, I1', be kept in normal position as above defined with the rearward passageways 59, 59 closed, and that the tension of the adjustable spring 93 be' so regulated that the forward passageways 49, 49 are also closed.

Reference now being had more particularly to Figs. rI and 9: The eddy current to the rear of the downwardly projecting rearward wall of the leading edge section or nosepiece with'the forward passageway 49 open and the airfoil at the v cated in Fig. 8. This is due in part to the cooperative action of the downwardly extending portion of the rearward wall of the leading edge y section or nosepiece I6 and the trailing edge section or flap Il in its lowered position.l Furthermore as in the case of Fig. 8, the airstream does not strike the forward wall of the main supporting section which forms the vane or blade of the passageway 49. A greater decrease in drag therefore due to these factors is characteristic of the airfoil as. shown in Fig. 9 than as shown in Fig. 8. Comparing the showing of Fig. 9 with that of Fig. 7, in this respect it will be observed that in Fig. 7 the eddy current beneath the airfoil is still inconsequential.

In Fig. 9 the eddy formed to the rear of the downwardly projecting portion of the rear wall of the main supporting section characterizing Fig. 8 is eliminated vand instead the forward wall of the trailing edge section or flap Il cooperates with the rear wall of the main supporting section in directing pressure air upwardly through the rearward passageway 59. As a result of this drag is reduced, as will now appear in the discussion of the outlet ports of the two passageways.

In Fig. 9 the decrease in drag due to the opening of the outlet ports of the passageways 49 and 59 at the top of the airfoil is very marked. It will be apparent that as to the passageway 49 the air projected therethrough being entirely to the rear of the maximum ordinate of the upper camber occasions no impact resistance whatsoever to the front of that maximum ordinate but on the contrary sweeps along over the upper surface of the main supporting section and tends to prevent the vortices which are there present in the showing of Fig, 7. The airstream projected through the outlet port of the rearward passageway 59 sweeps rearwardly and downwardly along the upper surface of the trailing edge section or flap and tends to prevent the trailing edge vortices there characterizing the structure of Fig. 7 which are so pronounced in that structure that with the angle of attack there shown the plane is very near to the critical angle or burble point. In Fig. 9, as in Fig. 8, the concave under suraface of the trailing edge section or ap il directs the airstream beneath in line with the airstream above and adds its iniiuence to the reduction of the trailing edge vortices otherwise formed. In Fig. 7 on the contrary the airstream beneath the trailing edge section or flap is bent up over the edge thereof and greatly contributes to the harmful vortices there indicated.

The loss of lift occasioned by the upturned position of the trailing edge section or flap Il in Fig. 8 is no longer present with the trailing edge section or ap turned down in the position of Fig. 9. In this respect, therefore, the lift coefficients in Figs. 7 and 9 are substantially alike. In Fig. 9, however, there are two factors not present in Fig. 7 which increase the lift. The first of these is the advance in the center of pressure, due to the combined effect of the downwardly projecting portion of the rear wall of the leading edge section or nosepiece I6 and the trailing edge section or flap I'I in its lowered position in intensifying the eddy current beneath the main supporting section and in directing' pressure air through the passageway 49; and the second is the force developed within the turbine passageways themselves heretofore referred to and more specifically fully set forth in my said U. S. Letters Patent No. 2,077,070. These two factors give the airfoil, as shown in Fig. 9, far

greater lift than has the airfoil as shown in Fig. 7. In addition the airfoil as shown in Fig. 9 has the same potentialities of increased lift over the airfoil as shown in Fig. 7, as above set forth respecting the airfoils of Figs. 8 and 6, due to the greater speeds attainable by reason of the decrease in drag.

It is recommended that both passageways be open and the trailing edge'section or ap be in its lower position for takeoff after attaining sufficient speed on the level, for landing and for rising where angles of attack are desired above as illustrated in Figs, 7 and 9 are advisory and not compulsory. The pilot knowing the characteristics and functioning of the invention as above set forth and being skilled in the art will use his best judgment in how most eiciently to make use of the said characteristics and functioning of this invention in the control of his plane in meeting the various conditions of takeoff, landing and flight encountered.

The foregoing detailed description has been given for clearness of understanding and no undue limitation should be deduced therefrom but the appended claims should be construed as broadly as possible in View of the prior art.

I claim:

1. An airfoil for an airplane provided with a plurality of vanes or blades forming one or more substantially spanwise passageways extending through the airfoil from the lower surface to the upper surface thereof, the vanes or blades being formed with cooperatingcurved surfaces and being so constructed and arranged that the said passageways have their inlet ports at the bottom of the airfoil to the front of the outlet ports at the top of the airfoil with the cross-sections of the passageways diminishing gradually from the inlet to the outlet thereof and the mean cross-sectional line of the passageways gradually flattening from inlet to outlet with no appreciable straight line passage for air through the passageways from inlet to outlet, the curved surfaces of the cooperating vanes or blades of each passageway extending rearwardly at the bottom and the forward vane or blade extending downwardly below the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade on the flight of the airplane tending to inducean eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil.

2. An airfoil for an airplane provided with a plurality of vanes or blades forming one or more substantially spanwise passageways extending through the airfoil from the lower surface to the upper surface thereof, the vanes or blades being formed with cooperating curved surfaces and being so constructed and arranged that the said passageways have their inlet ports at the bottom of the airfoil to the front of the outlet ports at the top of the airfoil with the cross-sections of the passageways diminishing gradually from the inlet to the outlet thereof and the mean crosssectional line of the passageways gradually attening from inlet to outlet, means providing for opening and closingthe passageways at the top, means for controlling the extent to which the said passageways may be opened from a substantially complete closure thereof to a maximum opening in which substantially no air can fiow through the passageways in a straight line, the forward vane or blade of each passageway extending downward below the lower surface of its cooperating rearward vane or blade in closed position of said passageways, the downwardly extending vane or blade on the flight of the airplane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil.

3. An airfoil for an airplane provided with a plurality of vanes or blades forming a substantially spanwise passageway extending through the airfoil from the lower surface to the upper surface thereof, the vanes or blades being formed with cooperating curved surfaces and being so constructed and arranged that the cross-section of the said passageway diminishes gradually from the inlet to the outlet thereof and thel mean crosssectional line of the passageway gradually fiattens from inlet to outlet with no appreciable straight line passage for air through the passageway from inlet to outlet, means providing for opening and closing the passageways at the top, the inlet port of the passageway at the bottom being forward of the maximum ordinate of the top camber curve and the outlet port of the passageway at the top being rearward of said maximum ordinate, the curved surfaces of the coope'rating vanes or blades extending rearwardly at the bottom and the forward vane or blade extending downwardly below `the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade on the flight of the airplane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil.

4. An airfoil for anairplane provided with a 4plurality of vanes or blades forming one or more substantially spanwise passageways extending through the airfoil from the lower surface 4to the lupper surface thereof, the vanes or blades being formed with cooperating curved surfaces and being sov constructed and arranged that the said passageways have their inlet ports at the bottom of the airfoil to the front of the outlet ports at the top of the airfoil with the cross-sections of the passageways diminishing gradually from the inlet to the outlet thereof and the mean crosssectional line of the passageways gradually flattening from inlet to outlet, means for controlling the extent to which the said passageways may be opened from a substantially complete closure thereof to a maximum opening in which substantially no air can flow through the passageways in a straight line, means providing for automatic opening of the passageways at a predetermined positive angle of attack and for automatically effecting closure thereof at lesser angles of attack, said opening and closing of the passageways being at the top thereof, the forward vane or blade of each passageway extending downward below the lower surface of its cooperating rearward vane or blade in closed position of said passageways, the downwardly extending vane or blade on the flight of the plane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil.

5. An airfoil for an airplane provided with a plurality of vanes or blades forming a substantially spanwise passageway extending through the airfoil from the lower surface to the upper surface thereof, the vanes or blades being formed with cooperating curved surfaces and .being so constructed and arranged that the said passageway is of the turbine type and has its inlet port at the bottom forward of the maximum ordinate o-f the top camber curve and its outlet port at the top rearward of said maximum ordinate, the curved surfaces ofthe cooperating vanes or blades extending rearwardly at the bottom and the forward vane or blade extending downwardly below the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade on the flight of the airplane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil, means for controlling therextent to which the said passageway maybe opened from a substantially complete closure thereof to a maximum opening in which substantially no air can ow through the passageway in a straight line, and means providing for automaticl opening of the passageway at a predetermined positive angle of attack and for automatically effecting closure thereof at lesser angles of attack.

6. An airfoil for an airplane provided with a plurality of vanes or blades forming a substantiallyspanwise passageway extending through the airfoil from the lower surface to the upper surface thereof, the vanes or blades being formed with cooperating curved surfaces and being so constructed and arranged that the said passageway is of the turbine type and has its inlet port at the bottom forward of the maximum ordinate of the top camber curve and its outlet port at the top rearward of said maximum ordinate, the curved surfaces of the cooperating vanes or blades extending rearwardly at the bottom and the forward Vane or blade extending downwardly below the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade on the flight of the airplane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil, means for controlling the extent to which the said passageway may be opened from a substantially complete closure thereof to a maximum opening in which substantially no air can flow through the passageway in a straight line, means providing for automatic opening of the passageway at a predetermined positive angle of attack and for automatically effecting closure thereof at lesser angles of attack, and means correlated with the last named means for effecting manual opening and closing of the passageways at the will of the operator.

7. An airfoil for an airplane provided with a nosepiece terminating at the rear in a wall 'constituting a vane or blade, a second vane or blade mounted to the rear thereof, the said vanes or blades forming a substantially spanwise passageway extending through the airfoil from the lower surface to the upper surface thereof, the said vanes` or blades being formed with cooperating curved surfaces and being so constructed vand arranged that the said passageway has its inlet port at the bottom forward of the maximum ordinate of the top camber curve and its outlet port at the top rearward of said maximum ordinate with the cross-section of the passageway diminishing gradually from the inlet to the outlet thereof and the mean cross-sectional line of the passageway gradually flattening from inlet to outlet with no appreciable straight line passage for air through the passageway from inlet to outlet, the curved surfaces of the two vanes or blades extending rearwardly at the Ibottoni and the forward vane or blade extending downwardly below the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade on the flight of the airplane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil.

8. An airfoil for an airplane provided witha nosepiece 'terminating at the rear in a wall constituting a vane or blade, a second vane or blade mounted to the rear thereof, the said vanes or 'blades forming a substantially spanwisepassageway extending through the airfoil from the lower surface to the upper surface thereof, the said vanes or blades being formed with cooperating curved surfaces and being so constructed and arranged that the said passageway is of the turbine type and has its inlet port at the bottom forward of the maximum ordinate of the top camber curve and its outlet port at the top rearward of said maximum ordinate, the curved surfaces of the two vanes or blades extending rearwardly at the bottom and the forward vane or blade extending downwardly below the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade on the flight of the airplane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil, means for controlling the extent to which the said passageway may be opened from a substantiaily complete closure thereof to a maximum opening in which substantially no air can flow through the passageway in a straight line, and means providing for automatic opening of the passageway at a predetermined positive angle of attack and for automatically effecting closure thereof at lesser angles of attack.

9. An airfoil for an airplane provided with a nosepiece terminating at the rear in a wall constituting a vane or blade, a. second vane or blade mounted to the rear thereof, the said vanes or blades forming a substantially spanwise passageway extending through the airfoil from the lower surface to the upper surface thereof, the said .-vanes or blades being formed with cooperating said maximum ordinate, the curved surfaces of the two vanes or blades extending rearwardly at the bottom and the forward vane or blade extending downwardly below the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade on the flight of the airplane tending to induce an eddy current of air to the rear thereof in a forward direction along the under surface of the airfoil, means for controlling the extent to which the said passageway may be opened from a substantially complete closure thereof to a maximum opening in which substantially no air can flow through the passageway in a straight line, means vproviding for automatic opening of the passageway at a predetermined positive angle of attack and for automatically effecting closure thereof at lesser angles of attack, and` means correlated with the last named means for effecting manual opening and closing of the passageway at the will of the operator. y

10. An airfoil for an airplane comprising a main supporting section and a trailing edge section or flap pivotally attached thereto, the main supporting section terminating at the rear in a wall constituting a vane or blade, the trailing edge section or flap terminating at the front in a wall constituting a vane or blade, the said vanes or blades forming a substantially spanwise passageway extending through the 'airfoil from the lower surface to the upper surface thereof, the vanes or blades being formed with cooperating curved surfaces and being -so constructed and arranged that the said passageway is of the turbine type; the said forward vane or blade of the said passageway extending downwardly below the lower surface of its said cooperating rearward vane or blade in closed position of the s aid passageway, the curved surface of the said rearward vane or blade extending rearwardly at the bottom; the said trailing edge section or flap having a normal position for straight-away flight with its upper surface substantially parallel with the reference chord line of the air foil as conventionally drawn, the said passageway being closed at the top in said normal position of the trailing edge section or flap and gradually opened as the trailing edge section or flap is moved downwardly from its normal position; the said downwardly extending forward vane or blade of the said passageway on the flight of the said airplane with the trailing edge section or flap in normal position tending to prevent impact resistance on the rearward vane or blade.

11. An airfoil for an airplane comprising a. main supporting section and a trailing edge section or flap pivotally attached thereto, the main supporting section terminating at the rear in a wall constituting a vane or blade, the trailing edge section or flap terminating at the front in a wall constituting a vane or blade, the said vanes or blades forming a substantially spanwise passageway extending through the airfoil from the lower surface to the upper surface thereof, the vanes or blades being formed with cooperating curved surfaces and being so lconstructed and arranged that the said passageway is of the turbine type; the said forward vane or blade of the said passageway extending downwardly below the lower surface of its said cooperating rearwardY vane or blade in closed position of the said passageway, the said curved surface of the rearward vane or blade extending rearwardly at the bottom; the upper surface of the said trailing edge section or flap to the rear of its said forward wall being substantially flat and the under surface thereof being formed with concave curvature from front to back, the upper and lower surfaces meeting to form the trailing edge at the rear; means for controlling the extent to which the said passageway may be opened from a substantially complete closure thereof to a maximum opening in which substantially'no air can flow through the passageway in a straight line, the said trailing edge section or flap having a, normal position for straightaway ight with its upper surface substantially parallel with the reference chord line of the airfoil as conventionally drawn; the said passageway being closed at the top in said normal position of the trailing edge section or flap and gradually opened as the trailing edge, section or flap is moved downwardly from its normal position; the said downwardly extending forward vane or blade of the said passageway on the flight of the airplane with the trailing edge section or flap in normal position tending to prevent impact resistance on the said rearward vane or blade, the concave under surface of the trailing edge section or flap when lowered to open the said passageway on the flight of the airplane cooperating with the said downwardly extending forward vane or blade to direct pressure air through the said passageway and increase the lift and decrease thedrag of the airfoil.

12. An airfoil for an airplane comprising a.

nosepiece, a main supporting section, and a flap; the nosepiece terminating at the rear in a wall constituting a vane or blade, 'the main supporting section at the front terminating in a wall constituting a vane or blade, the said vanes or blades tuting a vane or blade, the two last specied vanes or blades forming a substantially spanwise passageway at the rear of the airfoil extending through the airfoil from the lower surface to the upper surface thereof; the first mentioned pair of vanes or blades and the second mentioned pair of vanes or blades being respectively formed' port at the bottom forward of the maximumI ordinate of the top camber curve and its outlet port at the top rearward of said maximum ordinate and having its forward vane or blade extending downwardly below the lower surface of its cooperating rearward vane or blade, the downwardly extending vane or blade of the forward passageway on the flight of the airplane. tending to induce an eddy current of,y air to the rear thereof in a forward direction along the under.

surface of the main supporting section of the airfoil; and means under the oo ntrol'of the pilot for opening the said passageways at the top when the iiap is lowered and for closing the said passageways when the flap is raised.

13. An airfoil for an airplane comprising a nosepiece, a main supporting section, and a nap having a normal position for straight-away night with its upper surface substantially parallel with the reference chord line as conventionally drawn; the nosepiece terminating at the rear in a wall constituting a vane or blade, the main supporting section at the front terminating in a wall constituting a vane or blade, the said vanes or blades forming a substantially spanwise passageway at the front of the airfoil extending through the airfoil from the lower surface to the upper surface thereof; the main supporting section terminating at the rear'in a wall constituting a vane or blade', the ilap terminating at the f-ront in a wall constituting a vane or blade, the two last specified vanes or blades forming a substantially spanwise passageway at the rear of the airfoil extending through the airfoil from the lower surface to the upper surface thereof; the first mentioned pair of vanes or blades and the second mentioned pair of vanes or blades being respectively formed with cooperating curved surfaces and being so constructed and arranged that the respective passageways formed and defined thereby have their inlet ports' at the bottom of the airfoil to the front of the outlet ports at the top of the airfoil with the cross-sections of the passageways diminishing gradually from the inlet tothe outlet thereof and the mean cross-sectional line of the'passageways gradually flattening from inlet to outlet with no appreciable 3 straight line passage for air through the passageways from .inlet to outlet; vthe forward passageway having its inlet port at the bottom forward of the maximum ordinate of the top camber curve and its outlet port at the top rearward of said maximum ordinate and having its forward vane or blade extending downwardly below the lower surfaceof its cooperating rearward vane or blade, the downwardly extending vane or blade of the forward passageway on the iiight of the airplane tending to induce aneddy current of air to the rear thereof in asforward directipn along the under surface of the main supporting section of the airfoil; the said passageways being closed at the top in said normal position of the ap; and means under the control of the pilot for gradually opening the said passageways as the nap is lowered from its said normal position and for gradually closing the said passageways as the flap is raised from a lowered position to its said normal position. Y

WILLIAM K. ROSE.

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