US3486720A

US3486720A - Continuous slot forming leading edge slats for cranked wings

Info

Publication number: US3486720A
Application number: US688735A
Authority: US
Inventors: Henry M Seglem; John K Wimpress
Original assignee: Boeing Co
Current assignee: Boeing Co
Priority date: 1967-12-07
Filing date: 1967-12-07
Publication date: 1969-12-30
Anticipated expiration: 1986-12-30

Description

EFEEW -asm72s CONTINUOUS SLOT FORMING LEADING EDGE SLATS FOR GRANKED WINGS Filed Dec. 7, 1967 I .& .1.

Dec. 30. 1969 H. M. SEGLEM ET AL 5 Sheets-Sheet l INVENTORS HENRY M. SEGLEM JOHN K. W/MPRESS Dec. 30. 1969 H. M. SEGLEM ET AL CONTINUOUS SLOT FORMING LEADING EDGE SLATS FOR CRANKED WINGS Filed Dec. 7, 1967.

5 Sheets-Sheet 2 INVENTORS' HENRY M. SEGL EM BY JOHN K. WIMP/ms AGENT Dec. 30. 1969 H. M. SEGLEM ET AL CONTINUOUS SLOT FORMING LEADING EDGE SLATS FOR CRANKED WINGS Filed Dec. 7, 1967 5 Sheets-Sheet 3 mm in 5MP m v K. H M m Dec. 30. 1969 H. M. SE GLEM ET AL 3,486,720

CONTINUOUS SLOT FORMING LEADING EDGE SLATS FOR CRANKED WINGS Filed Dec. 7 1967 5 Sheets-Sheet 4 co/vmvuous 'swr NO/V-(ONTINU'OUS SLOT Dec. 30. 1969 H. M SEGLEM AL CONTINUOUS SLOT FORMING LEADING EDGE SLATS FOR CRANKED WINGS Filed Dec. 7, 1967 5 Sheets-Sheet 5 6 7 NF m? XF mm 5 3| x? h. m uh mw i =3. y \Jfi. Sm Sm magfigqu L3 bgfisu 2 aw E mm ztzpu N\ .& NYSE wazm w -mw .m Q .Q;\ 4%

INVENTORg HENRY M. SEGL EM 5 am K. W/MPRESS AGENT United States Patent 3,486,720 CONTINUOUS SLOT FORMING LEADING EDGE SLATS FOR CRANKED WINGS Henry M. Seglem, Melbourne, Fla., and John K. Wimpress, Seattle, Wash.,' assignors to The Boeing Company, Seattle, Wash., a corporatiou of Delaware Filed Dec. 7, 1967, Ser. No. 688,735 Int. Cl. B64c 3/38 US. Cl. 244-42 13 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Field of the invention This invention is classified in class 244, subclass 43, Airfoils having their lift varied by a change in the area of their surface in plan view, at will or in response to changing conditions.

Description-of the prior art The problem of controlling the vortex over a cranked wing strake juncture has been attempted by many devices, but none of the prior art has been found to include, teach, or suggest the disclosed solution of a pair of slats producing a continuous'slot when extended on the cranked wing. Assignees application, Ser. No. 645,254, filed June 12, 1967, now Patent No. 3,447,761 noting FIG. 5 particularly, shows the typical clearance space between the adjacent ends of outboard and inboard leading edge slats and each of the three search patents, 3,142,457; British 791,423; and British 991,405. clearly fail to show an aerodynamically continuous slot through the wing strake juncture. The inventors of the three latter patents either ignored the problem, couldnt solve the problem of obtaining lift from the small area or crack between the two adjacent slats, or did not know of the superior additional lift and improved stability obtainable by designing slats that provide a continuous slot at the juncture of cranked wings.

SUMMARY OF THE INVENTION The disclosed invention comprises a pair of retractable slats on the leading edge of a cranked wing, i.e., the inboard leading edge portion having at least 45 of sweepback and the outboard leading edge portion having less than 45 of sweepback, particularly as on a highly swept supersonic swingable wing in which the outer wing portion is pivoted forwardly for subsonic or slow speed flight. When the wing is swept back, the retracted leading edge slats are separated, one on each side of the wing strake juncture or pivot joint if the wirg is pivotal, and when the outer wing portion is swept forwardly, the retracted and separated slats are extended by being actuated forwardly until their adjacent ends touch in substantially air tight relationship to form an aerodynamically continuous slot along the wing leading edge through the wing strake juncture.

3,486,720 Patented Dec. 30, 1969 Three different basic actuators for extending and retracting the slats from the wing leading edges are disclosed herein.

A principal object of this, invention is to provide a new method for improving stall, lift, and stability characteristics in a cranked swept wing.

Another principal object of this invention is to greatly improve the lift, stall, and stability characteristics of a cranked wing with leading edge slats by forming slats that provide an aerodynamically continuous slot around the wing strake juncture.

Another principal object of this invention is to provide leading edge slats for a cranked wing and which slats when extended, will contact each other in substantially an air tight joint to form a continuous leading edge slat through the wing strake juncture. w

Another object of this invention is to provide leading edge slats for a pivotal cranked wing, the wing comprising a highly swept inboard wing portion or strake and an outboard portion of substantially less sweep than the strake, and the slats when extended from the highly swept strake leading edge and from the less swept outboard wing portion leading edge meet each other at their adjacent edges in a parallel and air sealed relationship whereby a substantially air tight contact is made to provide an improved continuous slot through the wing strake juncture.

A still further object of this invention is to provide a new actuator for extending and retracting leading edge flaps, for actuating and controlling ailerons, or for extending and retracting trailing "edge flaps.

BRIEF DESCRIPTION OF FIGURES The drawings diagrammatically illustrate by way of example, not by way of limitation, three forms of the invention wherein like reference; numerals designate corresponding parts in the several views in which:

FIG. 1 is a perspective view of the right pivotal wing on a subsonic, supersonic, or faster aircraft with the wing in fully swept position and with the new leading edge slats retracted into the wing;

FIG. 2 is a perspective view of the wing of FIG. 1, but with the outer wing portion swept forward forming a cranked wing, and the leading edge slats being in extended position;

FIG. 3 is an enlarged view of one embodiment of the wing strake juncture with the slats illustrated in extended position in solid lines and in retracted position in phantom lines with the outer wing and; slat portions cut away, and showing particularly the resi lting substantially airtight seal between the edges of the y-arying thickness slat;

FIG. 4 is an enlarged sectional view outboard of the wing strake juncture of one of a pair of similar slats of a second embodiment illustrated in extendefel and lowered position in solid lines, in extended position only in broken lines, and in retracted position in phantom lines;

FIG. 5 is a view taken at 5-5 on FIG. 4 illustrating the shaft bent end with a roller operable in a track in the flap;

FIG. 6 is an enlarged sectional view outboard of the wing strake juncture of one of a pair of similar slats of a third embodiment illustrated in extended position in solid lines and in retracted position in phantom lines; and

FIGS. 7 to 10 are performance curves from test data illustrating the great and unexpected results in a cranked wing having the new continuous leading edge slat as compared with the same wing with the conventional unconnected leading edge slats; FIG. 7 being the C (coefficient of lift) versus C (coefficient of drag) curves, FIG. 8 being the C v. at (angle of attack) curves, FIG. 9 being the a v. C (coefiicient of moment) curves, and FIG. 10 being the C v. C curves.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention, the scope of which being defined in the appended claims, is not limited in its application to the details of construction and arrangement of parts shown and described-,Since the invention is capable of other embodiments and of being practiced or carried out in various other ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

FIG. 1 discloses a supersonic or faster aircraft with a highly v swept wing, the inboard wing portion or strake 11 of which having a leading edge 12 of at least 45 degrees sweep back, for example, and the outboard wing portion 13 having a leading edge 14, the outboard portion of the preferred wing being connected to the inboard wing portion with a pivot 15, such as but not limited to the wing pivot disclosed in assignees application by H. A. Dethman, Ser. No. 587,290, filed Oct. 17, 1966, now abandoned, a continuation-in-part of his US. Patent 3,279,721. Retracted

slats

16 and 17 having

adjacent ends

18 and 19, respectively, lie flush in the

wing leading edges

12 and 14, respectively, when the wing is in fully swept back position.

FIG. 2 shows the inventive leading

edge slats

16 and 17 in fully extended position on a cranked wing, i.e. a wing in which the inboard leading edge has a sweep of 45 or more and the outboard leading edge has a sweep of lessthan 45, or there being at least a substantial difference in sweep, such as at least 30, between the leading edges of the inboard and outboard wing portions. While not deemed as effective, the invention can be utilized on wings having less than 30 difference in leading edge sweep, if so desired. With the

slats

16, 17 thus intended, the adjacent slat ends 18 and 19 contact each other in substantially an air tight seal between the slats. 1

While this invention is very useful on any fixed cranked wing, it is particularly advantageous for use on variable sweep wings, as disclosed in FIG. 3, in providing an aerodynamic seal between the extended slat ends when the outer wing portions are swept forwardly relative to the inner wing positions.

As for the novel shape of the inboard and outboard slats, 16 and 17, respectively, on the illustrated right wing, each slat may be the allochiral analogue of the other.

Outboard slat 17, for example, starts with mating knife edge 19 and thickens to the required or desired thickness as illustrated on the slat in FIG. 3. From this point of desired thickness, the thickness pr the slat is constant to the outer end of the slat adjacent the wing tip.

For simplicity of illustration, inboard slat 16 begins with the desired thickness and just short of the other end, the thickness tapers to the knife edge 18 for mating with the adjacent or contiguous knife edge 19 of the outboard slat 17. If so desired, another preferred shape for the inner end of slat 16 and outer end of slat 17 is a tapered end similar to the other tapered ends. The principal feature is stillthe resultant highly efiicient slot through the cranked wing juncture.

MODIFICATION OF FIG. 3

FIG. 3 discloses more details of one embodiment of the invention showing the extended inboard and

outboard slats

16 and 17 respectively, with their adjacent respective ends 18'; and 19 in an areodynamic sealing relationship or pressed into an air sealing contact with each other, as illustrated. Inboard slat 16 is supported on the inboard wing portion 11 with arcuate bars, FIG. 3 showing one bar 20 wherein the forward end of the bar is fixed to the slat 16 with flush rivets, for example, and the aft rod end is operably mounted between upper horizontal rollers 21, vertical side rollers 22, and lower horizontal rollers 23, Outboard slat 17 is supported simi- 4 larly by the above described inboard slat, as by arcuate bar 24, FIG. 3, for example.

A conventional suitable piston and cylinder hydraulic motor or acuator 25, FIG. 3, is pivotally connected between the inboard wing 11 and inboard slat 16 for extension and retraction of the slat 16. Several actuators may be utilized as required. Likewise, outboard slat 17 is operated with similar actuators, as actuator 26, FIG. 3, for example, whereby forward and downward movement is imparted to the slat by the arcuate bar 24 as the actuator is extended.

The result of this modificaton is the meeting in an aerodynamic seal, i.e., substantially airtight, of the adjacent ends of two slats on a cranked wing for forming an aerodynamically continuous slot between the slats and the wing, particularly through the cranked wing juncture.

MODIFICATION OF FIG. 4

ACTUATOR Actuator 27, FIGS. 4 and 5, comprises a rotatable, push-pull shaft 28 having ballnut 29 rotatably mounted thereon and terminating with an off-set arm 30. A roller 31 rotatably mounted on the end of off-set arm 30 rolls in track 32 on slat 17a. Shaft 28 is rotated by its gear 35 driven by manually controlled motor 38 through approximately 180 rotation.

Slat 17a, FIGS. 4 and 5, is pivotally secured through its supporting yoke 33a to ballnut 29 with short pins 34a, one on each side of the ballnut.

Slat 17a is maintained fixed about its lateral axis with the pins 34a operable in straight grooves (not shown) in the wing leading edge.

In operation, push-pull shaft 28, FIG. 4, is moved forwardly from the dot-dash phantom line position to the broken line position. Then'shaft 28 comes in contact with and is rotated 180 by motor 38 to rotate off-set arm 30 and accordingly to move slat 17a from the broken line position to the solid line position illustrated on FIG. 4 and FIG. 5, the latter being a view taken at 55 on FIG. 4. The inboard slat ofthis embodiment is similar to the above disclosed outboard slat 17a, FIGS. 4 and 5. With both inboard (not shown) and outboard 17a slats extended, their adjacent knife edge ends contact each other at the wing strake juncture in an aerodynamic seal similar to that shown in FIGS. 2 and 3 of the first modification.

Rotation of axially slidable push-pull shaft 28 may be controlled further by an independent pilot control source of motor 38 for varying the .angle of downward tilt of the slat from the wing as desired.

Also, if so desired and required by the particular aircraft, another form of the inventive actuator, the disclosed axially extendible and rotatable push-pull shaft may be incorporated in a training edge lift device, i.e., ailerons and trailing edge flaps for operation thereof.

MODIFICATION OF FIG. 6

FIG. 6, a sectional view through the outboard slat adjacent the actuator of another modification similar to that of FIGS. 4 and 5, discloses outboard slat 17b, similar to slat 17, extended from outer wing portion 13b with push-pull shaft 28b having helical grooves 37 operable with leading edge splines 36 and actuatable through approximately for rotating and lowering off-set arm 30b which in turn has roller 31b operable in slat track 32b for extending and lowering the outboard slat 17b.

The inboard slat and its actuating means (neither shown) of this FIG. 6 modification are similar to the above described outboard slat 17b and its actuating means 28b 34b, and both slats extend to contact each other for forming a continuous aerodynamic slot through the wing strake junction.

WIND TUNNEL RESULTS FIGSi 7 to disclose lift, drag, and pitchingcharacteristics as obtained from actual wind tunnel testing of a cranked wing with the continuous slot through the wing strake juncture formed by the contiguous and aerodynamically sealed slats and a cranked wing with the conventional non-continuous slot.

The expected gain of closing the slot was the additional lift due to the increase in slat area covered -by the slat as approximately /3 of 1% increase area. A typical 3 inch crack in a full 774 inch cranked wing slat would result in a .39 of 1% loss of wing area and accordingly a third of 1% increase of lift would be expected from merely filling the crack.

However, a much greater increase in lift was found from the continuous slat and resulting slot than the expected /3 of 1%. As evidenced by the test data results of FIGS. 7 and 8, increases in lift due to the slats air sealed end edges amounted to as high as or 17.6% at constant a. of 16, and decreases in drag amounted to as high as or 29.9% at constant C of 1.5.

FIGS. 9 and 10 demonstrate the important improvements in longitudinal stability. The angle for'initial instability is increased from 8 to permitting lift to increase from 1.1 to 1.6 before longitudinal instability (pitch-up) occurs. In addition, the region of instability is restricted to a small range of lift before the airplane becomes strongly stable again. This reduced region of instability results in greatly improved stall characteristics when compared to those of the non-continuous slot configuration.

While a method and only a few embodiments; of the invention have been shown in the accompanying specification and drawings, it will be evident that various other modifications are possible in the arrangement and construction of the disclosed continuous slot forming leading edge slats for cranked wings without departing from the scope of the invention.

We claim:

1. In an aircraft cranked swept wing in which the inboard leading edge is highly swept and the outboard leading edge is of at least 30 lss sweep angle and the intersection of the two leading edges forming a wing strake juncture, the improvement comprising a new method for improving stall, lift, and stability characteristics of said wing, said method comprising,

(a) retractably mounting a first slat on the wing inboard leading edge for moving between a retracted position and an extended position, the slat having an outer end, and retractably mounting a second slat on the wing outboard leading edge for moving between a retracted position and an extended position, the second slat having an inner end,

(b) forming the outer end of the first slat and the inner end of the second slat parallel to each other when in extended position,

(0) extending both slats to an extended position wherein each slat is substantially parallel to its wing leading edge, and

(d) pressing the outer end of the first slat into air sealing contact with the inner end of the second slat at the extended position for forming a substantially airtight seal therebetween for forming an improved continuous slot through said juncture for providing improved stall, lift, and stability characteristics.

2. In an aircraft cranked wing having a highly swept inboard leading edge and an outboard leading edge of at least 30 less sweep, the intersection of the two leading edges forming a wing strake juncture, and a slat extendible forwardly from each leading edge with said slat adjacent ends being at the wing strake juncture for forming a leading edge slot on said cranked wing, the improvement comprising a new method for greatly improving the stall, lift, and stability characteristics of said wing comprising,

('a) extending said slats until said slot is formed and the adjacent ends of said slats are parallel to each other, and

(b) extending said slats until the adjacent slat ends are in air sealing contact with each other to form a substantially airtight seal therebetween said ends at said wing strake juncture.

3. In an aircraft cranked swept wing in which the inboard leading edge is highly swept and the outboard leading edge is of at least 30 less sweep angle and the intersection of the two leading edges forming a wing strake juncture, the improvement comprising,

(a) leading edge slat means being movable by an actuating means from said leading edges between a re racted position and a forwardly extended position and having adjacent nds at said juncture when in extended position.

(b) said adjacent ends of said extended slat means being parallel with each other and when in extended position pressed into air sealing contact with each other to form a substantially airtight seal therebetween, and

(c) said end sealed slat means forming a continuous slot throughsaid juncture to provide greatly improved stall, lift, and stability characteristics in said wing.

4. In an aircraft as recited in claim 3 wherein said actuating means comprises,

(a) means for extending and lowering said slats from said leading edges,

(b) said slat being responsive to said extending and lowering means for positioning said slats forwardly and downwardly of said leading edges and for pressing said adjacent ends into an air sealing contact relationship with each other at said wing strake juncture. l

5. In an aircraft as recited in claim 4 wherein said extending and lowering means comprises,

(a) push-pull shaft means for extending said slats from said wing leading edges,

(b) rotatable oif-set arm me'ans on said shaft means for lowering said slats, and

(c) said rotatable off-set arm means being responsive to said push-pull shaft means for positioning said slats forwardly and downwardly of said leading edges and for pressing said adjacent ends into an air sealing contact.relationship with each other at said wing strake juncture.

6. In an aircraft 'as recited in claim 5 wherein said extending and lowering means comprises,

(a) ballnut means splined to said push-pull shaft means and adapted to be rotated by a controlled motor for rotating said sh'aft means, and

(b) said set-off arm means being responsive to said ballnut means for lowering said slats after they have been actuated forwardly by said push-pull shaft means for positioning said slats in contiguous relationship with each other at said wing strake juncture.

7. In an aircraft as recited in claim 5 wherein said extending and lowering means comprises,

(a) ballnut means connected to said push-pull shaft means and adapted to be rotated by helical grooves in said wing, and

(b) said off-set arm means being responsive to said ballnut means for lowering said slats simultaneously with forward actuation by said push-pull shaft means for positioning said slats in contiguous relationship with each other at said wing strake juncture.

8. In an aircraft having a wing with a leading edge and leading edge slats extendibly mounted on the leading edge of the wing, the invention comprising actuators in the wing for extending and retracting the slats comprising,

(a) rotatable push-pull shaft means for extending and retracting said slats at said wing leading edge,

(b) rotatable off-set arm means for said rotatable pushpull shaft means for raising and lowering said slats, and

(c) said rotatable off-set arm means being responsive to rotatable and push-pull movement of said rotatable push-pull shaft means for extending and lowering said leading edge slats.

9. In an aircraft as recited in claim 8 wherein,

(a) ballnut means is rotatably mounted on said pushpull sh'aft means,

. (b) one of said slats is pivotally connected to said ballnut means,

(c) pin and groove means for preventing rotation of said ballnut means as it is actuated fore and aft by said push-pull shaft means,

(d) a helical groove and spline connection between said push-pull shaft means and said wing leading edge, and

(c) said off-set arm means being responsive to said ballnut means and said push-pull shaft means for simultaneous lowering and forward actuation of said slats.

10. In an aircraft cranked swept wing in which the inboard leading edge is highly swept and the outboard leading edge is of at least 30 less sweep angle and the intersection of the two leading edges forming a wing strake juncture, the improvement comprising,

(a) forwardly movable slats mounted on each of said leading edges, said slats being movable by actuating means between a retracted position on said wing leading edges and an extended position forwardly of said leading edges with the adjacent slat ends being adjacent to said wing strake juncture,

(b) said adjacent slat ends of said extended slats being parallel with each other and pressed into air sealing contact with each other to form a substantially airtight seal therebetween, and

(c) said end sealed slats forming a continuous slot through said wing strake juncture for providing greatly improved stall, lift, and stability characteristics in said wing.

11. In an aircraft cranked swept wing in which the inboard leading edge is swept at least 45 and the outboard leading edge is swept less than" 45 and the intersection of the two leading edges forming a wing strake juncture, the improvement comprising,

12. In an aircraft cranked swept wing in which the inboard leading edge is highly swept and the outboard lead ing edge is of at least 30 less sweep angle and the intersection of the two leading edges forming a wing strake juncture, the improvement comprising,

(a) a slat for of said swept leading edges, means for mounting each of said slats for movement between a retracted position on its leading edge and an extended position spaced from its leading edge,

(b) said slats having two adjacent ends when in extended positions at said wing strake juncture and forming slots between said slats and said wing leadf n g (c) said adjacent ends being parallel with each other and when in extended position pressed into air sealing contact with each other to form a substantially airtight seal therebetween, and

(d) said end sealed slats forming said slots into one continuous slot through said wing-strake juncture for providing greatly improved stall, lift, and stability characteristics in said wing.

13. In an aircraft cranked swept wing in which the inboard leading edge is highly swept and the outboard leading edge is of at least 30 less sweep angle and the intersection of the two leading edges forming a wing strake juncture, the improvement comprising,

(a) said highly swept inboard leading edge having a forwardly movable inboard slat mounted thereon and said lesser swept outboard leading edge having a forwardly movable outboard slat mounted thereon, each of said slats being movable by actuating means between a retracted position on its leading edge and an extended position spaced from its leading edge,

(b) said inboard highly swept slat forming a highly swept slot between said inboard slat and said inboard leading edge and said outboard slat forming a lesser swept slot between said outboard slat and said outboard leading edge when both said slats are in eX- tended position,

(c) the outboard end of said extended inboard slat being parallel with the inboard end of said extended outboard slat adjacent to said wing-strake juncture and pressed into air sealing contact with each other to form a substantially airtight seal therebetween, and

((1) both said end sealed inboard and outboard slats forming one continuous slot through said wing strake juncture of said highly swept slot for providing greatly improved stall and stability characteristics.

References Cited UNITED STATES PATENTS 2,361,574 10/ 1944 Tampier 244-42 2,702,676 2/1955 Delaney 244-42 3,013,748 12/1961 Westburg 244-42 3,244,384 4/ 1966 Bracka et al. 244-42 3,285,542 11/1966 Holmquist 244-43 X MILTON BUCHLER, Primary Examiner JEFFREY L. FORMAN, Assistant Examiner US. Cl. X.R. 74-25; 244-46