Gap seal for flaps

June 29, 1948. o. e. holt 2,444,293

GAP SEAL FOR FLAPS

Filed June 18, 1943

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Patented June 29, 1948 2,444,293

UNITED STATES PATENT OFFICE

2,444,293

GAP SEAL FOR FLAPS

Oscar E. Holt, Ferguson, Mo., assignor to CurtissWright Corporation, a corporation of Delaware . :

Application June 18,1943, Serial No; 491,401

Claims.

i··

This invention relates to airplanes and more particularly to means for limiting the leakage flow of air in the gap or slot passing between, a stationary lifting structure or airfoil and a movable control structure, such as a flap when the movable structure is aligned or relatively undisplaced with respect to the stationary structure.

With the present form of flap arrangements and regardless of the flight attitude assumed by the airplane, when the flaps are moved into a neutral or up position, there is considerable leakage air which passes through the slot between the stationary and movable structures regardless of how well the union of the two structures is fashioned. This passage of air through the slot is due to the large differential of pressure between the air on the bottom face of the lifting structure and the air on the top face of the lifting structure. At such times, this leakage at the outlet of the slot does no good since it creates great turbulence over the upper face of the movable structure, resulting in loss of lift and in horse power loss in the propelling of the airplane. Also this air in passing through the slot often deposits ice therebetween causing the movable structure to stick to the stationary structure when its use is desired. In addition to the ice. actually, pre venting relative movement of the structures, it will also, by being deposited on the nose face of the control structure, spoil the contour thereover and set up a detrimental turbulence of air.

It is an object of the present invention to provide means which will automatically come into play upon the movable control structure being moved to its position in alignment with the lifting structure to close off the air slot between the movable structure and the stationary structure.

It is another object of the invention to provide a slot closing means which is resilient and adapted, to be depressed Upon the movable surface being returned to the level flight or undisplaced position whereby any deviation in tolerances or wear will not greatly affect the efficiency of the slot closing means.

According to the present invention there has been provided within the flap arch assembly of the stationary structure, a strip of resilient material. such as rubber, running coextensively therewith. This resilient material, upon the flap being returned to its up position, is depressed and its shape distorted whereby the engagement of the flap with the same is positive and the flow of air is efficiently sealed off. This; strip extends only a small distance rearwardly of the air face and not to such an extent as to interfere with (Cl. 244—42) the larger flow of: air through the slot which is desired when the flap is moved to its: down or displaced position.

For other objects and for a better: understand³ ing of the invention, reference may be had to the following detailed· description taken ta connection with the accompanying drawing, in which.

Fig. 1 is a fragmentary view taken through an airfoil· section' at a point thereon where the flap 10 is connected.

Fig. 2 is a perspective view looking at the face of the arch assembly of the stationary structure and the strip of sealing material running therealong.

’’> Fig. 3 is an enlarged sectional view showing one form of resilient material and with this material depressed due to engagement of the flap : with the same to effect thereby the sealing of the airslot. - :

Fig. 4 is a. sectional view of a modified form of resilient material also depressed as when the flap is in its up position· to; close off the airslot.

Referring now. particularly to Figs. 1 and 2, there is shown a stationary lifting or wing struc²⁵ ture 10 having an arch assembly H within which there is connected a movable control structure or flap 12. An upper face 13 of the stationary structure 10 extends considerably rearwardly of a lower face 14 thereof. The control structure i 2 30 has a nose portion 15 and between it and the: arch assembly if there is, even in the best of designs, an airslot or gap 16 through which air leaks. This leakage flow of air through the airslot is great inasmuch as there is a large fliffer35 ence of pressure of the air between the lower and upper faces of the stationary surface 10. The velocity of the air at an outlet 17 at the end of the upper surface 13 is high and such as to cause considerable eddying of air above the flap 10 with consequent loss of lift.

The movable structure 42 is so connected to the stationary structure by hinge elements adapted to extend through openings 18 in the arch assembly that the movement with the flap or mov45 able structure 12 to its down position causes not: only a downward movement of the flap; but a rearward movement so as to enlarge the width of the slot 16 whereby a greater flow of air may be had through the slot at a time of takeoff or so landing: when such flow is desired over the upper surface of the flap for its scavenging: action thereon to-increase lifting power thereof. A mechanism for moving the flap is shown at 19, Fig. 1, in which there is incorporated a pair of upper 55 and lower links 20 and 21 adapted to be operated

2,444,293 from a lever 22 which is in turn connected to a fluid actuator 23.

Along the arch assembly I I, there is extended a strip 25 of resilient material. This strip runs coextensively of the arch assembly except for a break at opening 18 which allows for the connection of the movable structure to the stationary structure. One form of this resilient material is shown in Fig. 3 which is D-shaped in cross section and has its flat face secured to a wood backing member 28 which is connected flush with the arch assembly II. When the movable structure 12 is in its up position, the nose portion 15 will come into alignment with the strip and depress the same so that it assumes the distorted form shown by the full lines in Fig. 3. This is desirable to obtain a tight joint at 27 and to positively close off the slot 16.

In Fig. 4, there is shown another form 28 of a strip material which is of similar outside shape as the D-shaped strip 25 bitt of solid rubber and of such size that the wood backing is not required. As the movable structure 12 is rotated to depress the rubber, portions 29 of the material· will flow along· the face of the nose portion 15 thereby enlarging the contacting area between the resilient material 29 and the face of the nose portion 15.

It should be noted however, that the extent to which these strips of material project rearwardly of the arch assembly is small compared to the actual· distance between the arch assembly and the nose face of the flap when the flap is in its down position. This extent is thus not such that the great flow of air which is desired through the slot at times when the flaps are down is greatly impeded.

It should now be apparent that there has been provided means for limiting the flow of air through the slot between the stationary structure and the movable structure or flap which automatically comes into play as the movable structure is moved to its up position into alignment with the stationary structure.' With such a sealing arrangement, leakage air flow is stopped and the possibility of ice being disposed in the slot to such ah extent as to cause the movable surface to stick to the stationary surface no longer exists, nor will ice be allowed to form on the nose face of the movable structure such as to disrupt the flow of air over the movable structure surface upon the same being moved to its down position. ·

While various changes may be made in the detailed construction, it shall be understood that siiCh changes shall be within the spirit and scope of the present invention as defined by the appended claims.