US3570791A

US3570791A - Battened kite construction

Info

Publication number: US3570791A
Application number: US733599A
Authority: US
Inventors: Richard R Jackson
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-05-31
Filing date: 1968-05-31
Publication date: 1971-03-16
Anticipated expiration: 1988-03-16

Abstract

The specification describes a kite or kitelike device having substantially symmetrical wing sections made of highly flexible sheet material; stiffening battens are disposed at the leading edge of the wing sections to make the wing sections rigid in the chordal direction but yet permit free flexure of the wing sections in the direction of span.

Description

United States Patent [72] Inventor [54] BATTENED KITE CONSTRUCTION 6 Claims, 7 Drawing Figs.

[52] U.S.Cl 244/153 [51] Int. Cl B64c 31/06 [50] Field of Search 244/155 (FWD); 1 14/39, 103, 102; 244/16,43, 46,48, 154; 244/155,153

[5 6] References Cited UNITED STATES PATENTS 2,546,078 3/1951 Rogallo et a1 244/153 2,561,253 7/1951 Wells-Comes"... 114/102 2,737,360 3/1956 Allison 244/153 3,285,546 11/1966 Jalbert 244/155UX 3,396,921 8/1968 Rogallo 244/155UX Mechanicus Die Fliegende Untertasse October 1965 pages 404 407 Relied on.

Primary Examiner-Milton Buchler Assistant Examiner-Paul E. Sauberer Att0rneyWolf, Greenfield, & Sacks ABSTRACT: The specification describes a kite or kitelike device having substantially symmetrical wing sections made of highly flexible sheet material; stiffening battens are disposed at the leading edge of the wing sections to make the wing sections rigid in the chordal direction but yet permit free flexure of the wing sections in the direction of span.

mmmm a" 3570.791

SHEET 1 BF 2 3| INVENTOR RICHARD R. JACKSON FIG. 3 MW ATTORNEYS PATENIED'MARIBM 3,570,791

' SHEET 2 BF 2 RELATIVE WIND INVENTOR RICHARD R. JACKSON ATTORNEYS BATTENED KITE CONSTRUCTION SUMMARY OF THE INVENTION My invention is an improvement in the design of kites or aircraft of the type disclosed in US. Pat. No. 2,546,078 to Rogal- 10 et al. in which wing sections are formed from a highly flexible sheet material. Bridle lines are attached to the wing sections in a manner such that when the kite is presented to the wind the flexible wing sections will billow out in an arcuate pattern determined by the design and mode of attachment of the bridle strings. I have found that when the wing sections are completely flexible, as in the construction shown in the Rogallo patent, the kite must be flown at a relatively high angle of attack in order to sustain flight. Any attempt to decrease this relatively high angle of attack results in buckling of the leading edge of the kite, thus causing the-billowed wing sections to collapse. Attempts have previously been made to reinforce such kites by attaching a single reinforcing rib to the leading edge, the rib extending continuously along the span of the wing. Although reinforcing the leading edge in this manner does tend to reduce buckling at the leading edge at reduced angles of attack, it also reduces the flexibility of the wing in the span direction. This reduction of spanwise flexibility detracts from one of the advantages of such a flexible winged craft in that when the airspeed is varied (such as in gusty wind conditions) the arcuate contour of the wings changes to compensate for the change in airspeed. This compensating characteristic provides for a craft having relatively smooth flight characteristics. When the free flexure of the wings in response to varying wind conditions is prevented erratic flight behavior results.

My invention, contemplates reinforcing the leading edge of the wings so that they will not buckle and collapse at low angles of attack, yet this is accomplished in a manner that does not impair the spanwise flexibility of the wings. I have achieved these objectives by providing the leading edges of the wings with elongated stiffeners or battens. The battens extend from the leading edge rearwardly along the chord of the wings and are spaced laterally from each other.

The kite of my invention is of very light construction and may be easily folded to a compactness that is limited only by the length of the battens.

My invention, its objects and modifications, is described below with reference to the accompanying drawings wherein:

FIG. 1 is a plan view of the kite as it appears when flat;

FIG. 2 is a front view of the kite as viewed. along the lines 2-2 of FIG. 1;

FIG. 3 is a longitudinal vertical cross section of one of the battens taken along the line 3-3 of FIG. 1;

FIG. s is a transverse vertical c ross section of one of the battens viewed along the line 4-4 of FIG. 1;

FIG. 5 is a front elevation of the kite when in a billowed configuration during flight;

FIG. 6 is a side elevation of the kite in flight; and

FIG. 7 is a side elevation of a kite of the class described having a continuous reinforcing member at the leading edge thereof.

As illustrated in FIG. I, I prefer to make the kite of my invention from a flexible sheet material 5 such as Mylar or polyethylene; the sheet should be as thin as is practicably possible to reduce weight while retaining the desired degree of strength. I have found polyethylene sheets of two-thousandths of an inch thickness to be satisfactory. It may be desirable to reinforce the edges of the sheet 5 with a flexible paper or cloth tape 6 as long as the flexibility of the sheet 5 is not impaired. As shown in FIG. 2, a stiffening member 10 may be incorporated into the kite which extends along the centerline ll of the kite so that the kite may be considered as being divided into a pair of symmetrical wing sections 12. In the illustrated embodiment of my invention the stiffening member 10 is a length of flexible polyethylene tubing that is inflated by means of a valve generally indicated at 14 which is incorporated into the tubing. The stiffener 10 may be attached to the wing sections 12 by heat-sealing, tape or other convention means. It may as an alternative be formed integrally with the wing sections 12.

As an example of the relative dimensions of the kite and its component parts a kite wasmade in accordance with this invention. The kite was 6 feet in length and has a wing span, when layed flat, of 4 feet. The stiffener 10 was fabricated from 0.002 inches thick polyethylene sheet which was rolled into a tube 2 inches in diameter and heat sealed along the seam. The valve 14 was made from a short length of sterilizer tubing 13 in which was heat-sealed and taped to the stiffener 110. A small clamp 15 was used to close the tiller tube 13. In a kite of the 'above dimensions a pressure of about 3 psi was found sufficient to inflate the stiffener 10 to a rigid condition. This stiffener 10 is very light and may be easily inflated by a child.

FIGS. 2, 5 and 6 show a plurality of centerline bridle lines 16; these are connected by tape strips 18 or similar means to the stiffening member 10. The bridle lines 16 extend downwardly from the kite and are joined at a knot 20. Wing shroud lines 22 are attached to the tips 24 of the wing sections 12 by tape, heat-sealing or by other means, and extend downwardly to the knot 20 to which they are attached, the kite string 26 being attached to the

lines

16 and 22 at the knot 20. The dimensions of the bridle'lines 16 and wing tip lines 22 are such that when the kite is flown the flexible wing sections 12 will become filled by the relative flow of air and will assume a rounded configuration as illustrated in FIGS. 5 and 6.

I have found that in flying kites of this general type, having freely flexible leading edges 27, it is necessary to maintain the kite at a relatively high angle of attack with respect to the relative wind. Failure to maintain this high angle of attack resultsin buckling and flapping of the leading edge 27 which disrupts the flow of air past the kite and destroys the billowed contour edge 27 of the kite thus enabling the kite to be flown at smaller angles of attack. The battens 30 are secured to the leading edge 27 of each of the wing sections 12 and extend in a chordal direction (paralleling the centerline ll of the kite structure). The battens 30 are spaced spanwise (laterally) along the leading edge 27. The battens may be fastened to the wing sections 12 by means of a strip of flexible tape 32 as shown in FIGS. 3 and 4. Alternatively, batten pockets (not shown) may be formed integrally with the wing sections for accommodation of the battens 30. The battens 30 themselves may be fabricated from wire or slender strips of bamboo which may be heated and bent ina manner and for a purpose described below. In the 6-foot kite mentioned above, bamboo strips oneeighth inch square and 6 inches long were found to be satisfactory.

As shown in FIG. 3 the leading end of each of the battens 30 is bent upwardly so that the leading edge 27 of each wing section 12 will flare outwardly and upwardly. This outward and upward flare of the leading edge 27 provides a greater surface area of the underside of the wing sections, in the region of the leading edge 27, to be presented to the relative wind. It should be appreciated, therefore, that when the main body of each of the wing sections 12 is disposed at a relatively low angle of attack with respect to the relative wind (as indicated by the arrow 31 in FIG. 3), the outwardly flared leading edge 27 will catch and direct the wind to the underside of the kite thus sustaining the kite in flight. I have found that the use of battens 30 a that are bent upwardly at their leading ends so as to maintain the outwardly flared configuration of the leading edge of the wing sections enables a kite of this type to be sustained in flight with the rearward, unbattened portions of the wing sections l2 substantially paralleling the relative wind, this condition being satisfactorily maintained so long as a definite angle of attack is maintained between the relative wind and the underside of the outwardly flared leading edge 27 of the wing sections 12.

it should also be appreciated that the use of straight, uncnrved battens to rigidify the leading edge 27 in a chordwise direction will enable the kite to be flown at a smaller angle of attack than if the leading edge 27 were completely flexible in a chordwise direction, but will not sustain flight to the degree and at an angle or" attack achieved by using the aforementioned curved battens 30.

The spanwise spacing of the battens 30 should be great enough so as not to hinder the wing sections 12 from assuming their natural AC arcuate contours during flight. In the aforementioned 6-foot kite the battens were spaced at intervals of 4 inches.

It has been suggested the prior art that kitelike structures of the class described herein having highly flexible wing sections 12 may have utilization as giiders or space reentry vehicles. The advantages derived from the reinforcement of the leading edge 27 of the wing sections 12 in the above-described manner to enable the giider to sustain flight at very low angles of attack should be readily apparent in that it will enable the glider to maintain a relatively shallow glide angle, thereby considerably increasing the range of the glider. When the leading edges 27 of the wing sections 12 are completely flexible, the high angle of. attack needed to sustain flight would require that the glider descend at a relatively steep glide angle with a corresponding loss in range.

The prior art also suggests reinforcement of the leading edge 27 of the wing sections 12 by means of a continuous reinforcing member 35 that extends spanwise along the leading edge of the wing 12 as shown in FIG. 7. As mentioned earlier, although such a reinforcing member would make rigid the leading edge of the wing thus reducing the tendency of the leading edge of the wing to buckle and collapse as the angle of attack is decreased, the stiffening member would also reduce the spanwise flexibility of the wing 12. The instant invention serves to reinforce and make rigid the leading edge 27 of the wing 12 in a chordwise direction but enables the wing to retain its highly flexible characteristics a spanwise direction. Re-

tention of the characteristic of a high degree of spanwise flexi-' bility is important in a glider or kite of this type due to the fact that when the air speed of the craft is varied, as for example under gusty wind conditions, the billowed wing sections 12 tend to assume different arcuate configurations in a spanwise direction to compensate for the change in air speed. From this the disadvantage of providing a stiffening member that extends spanwise along the leading edge should be apparent in that it would tend to reduce the spanwise flexibility of the wing thereby tending to cause erratic flight behavior under varying air speeds.

l have also found that a kite constructed in this manner flies quite well without the aid of a tail.

The bridle lines 16 may be replaced by a heel 36 (see FIG. 7) which simply consists of a triangular sheet of material secured to and depending from the stiffening member 10. The wing shrouds 22 and kite string 26 are attached to the lower corner of the heel 36 at the juncture 20.

The foregoing is merely an illustrative embodiment of my invention and may be modified in its constructional or dimensional details without varying from the spirit of the invention.

lclaim:

1. An aerodynamically supportable device comprising:

a winglike member fabricated from a nonrigid, flexible material;

means for precluding chordwise flexure of the leading edge region of said winglike member while permitting said spanwise flexure thereof, said means precluding chordwise flexure comprising at least one relatively rigid batten of a width that is relatively small as compared to the span of said winglike member, said batten being secured to the leading edge of said winglike member and extending in a chordwise direction;

the forward portion of said at least one batten being bent upwardly to provide the leading edge of said winglike member with an upwardly oriented flare;

said flared region of the leading edge of said winglike member being effective to provide a greater angle of attack at the leading edge of the winglike member than at the more rearward portions of said winglike members.

2. An aerodynamically supportable device comprising:

a generally diamond-shaped sheet defining a pair of symmetrical nonrigid, flexible winglike members joint joined along a centerline, each of said winglike members extending transversely of said centerline;

means for maintaining said centerline region of said device in substantially rigid configuration at least during aerodynamic flight of said device; and

a plurality of transversely spaced battens secured to the leading edge of each of said winglike members in close proximity to each other and extending rearwardly and in substantially parallel relation to said centerline and to each other, said battens being relatively short in relation to the length of said device, the trailing ends of said battens being spaced forwardly of the trailing edge of said winglike members, said battens being of a width that is relatively small as compared with the span of their associated wing sections so as to enable said wing sections to be freely flexed in a transverse direction but to effectively preclude flexure of the leading edge of each of said wing sections in a direction paralleling said centerline, said device being capable of flight at very shallow angles of attack.

3. A device as claimed in claim 2 wherein:

the forward portion of said battens are bent upwardly to provide the leading edge of their associated winglike member with an upwardly oriented flare; said flared region of said leading edge of each of said winglike member being effective to provide a greater angle of attack at said.

leading edge of said winglike member than at more rearward portions of said winglike member whereby said device may be fi-own in an attitude in which those portions of said winglike members located rearwardly of said flared leading edge are disposed in an attitude making a negligible angle of attack with the relative wind.

4. A device as defined in claim 2 wherein said means maintaining said centerline region in a substantially rigid configuration comprises:

an elongated, hollow stiffener attached to said winglike members and extending along said centerline, said stiffener being fabricated from a flexible material;

valve means enabling said stiffener to be inflated to a relatively rigid condition; and

said valve means permitting said centerline region to be collapsed when said device is not in use to facilitate compact storage of said device.

5. A device as defined in claim 2 further comprising: a bridle including flexible lines secured to and aiong the centerline region of said device and extending downwardly therefrom; and a flexible bridle line connected to the lateral extremity of each of said winglike members, each of said bridle lines being connected at a common point below said device, said bridie being free of any other connections to said kite.

6. A device as defined in claim 2 further comprising means forming elongate pockets in said winglike members to receive and secure said battens therein.

Claims

1. An aerodynamically supportable device comprising: a winglike member fabricated from a nonrigid, flexible material; means for precluding chordwise flexure of the leading edge region of said winglike member while permitting said spanwise flexure thereof, said means precluding chordwise flexure comprising at least one relatively rigid batten of a width that is relatively small as compared to the span of said winglike member, said batten being secured to the leading edge of said winglike member and extending in a chordwise direction; the forward portion of said at least one batten being bent upwardly to provide the leading edge of said winglike member with an upwardly oriented flare; said flared region of the leading edge of said winglike member being effective to provide a greater angle of attack at the leading edge of the winglike member than at the more rearward portions of said winglike members.

2. An aerodynamically supportable device comprising: a generally diamond-shaped sheet defining a pair of symmetrical nonrigid, flexible winglike members joint joined along a centerline, each of said winglike members extending transversely of said centerline; means for maintaining said centerline region of said device in substantially rigid configuration at least during aerodynamic flight of said device; and a plurality of transversely spaced battens secured to the leading edge of each of said winglike members in close proximity to each other and extending rearwardly and in substantially parallel relation to said centerline and to each other, said battens being relatively short in relation to the length of said device, the trailing ends of said battens being spaced forwardly of the trailing edge of said winglike members, said battens being of a width that is relatively small as compared with the span of their associated wing sections so as to enable said wing sections to be freely flexed in a transverse direction but to effectively preclude flexure of the leading edge of each of said wing sections in a direction paralleling said centerline, said device being capable of flight at very shallow angles of attack.

3. A device as claimed in claim 2 wherein: the forward portion of said battens are bent upwardly to provide the leading edge of their associated winglike member with an upwardly oriented flare; said flared region of said leading edge of each of said winglike member being effective to provide a greater angle of attack at said leading edge of said winglike member than at more rearward portions of said winglike member whereby said device may be flown in an attitude in which those portions of said winglike members located rearwardly of said flared leading edge are disposed in an attitude making a negligible angle of attack with tHe relative wind.

4. A device as defined in claim 2 wherein said means maintaining said centerline region in a substantially rigid configuration comprises: an elongated, hollow stiffener attached to said winglike members and extending along said centerline, said stiffener being fabricated from a flexible material; valve means enabling said stiffener to be inflated to a relatively rigid condition; and said valve means permitting said centerline region to be collapsed when said device is not in use to facilitate compact storage of said device.

5. A device as defined in claim 2 further comprising: a bridle including flexible lines secured to and along the centerline region of said device and extending downwardly therefrom; and a flexible bridle line connected to the lateral extremity of each of said winglike members, each of said bridle lines being connected at a common point below said device, said bridle being free of any other connections to said kite.