US3125956A

US3125956A - Fold able fin

Info

Publication number: US3125956A
Authority: US
Publication date: 1964-03-24
Anticipated expiration: 1981-03-24

Description

March 24, 1964 s. KONGELBECK 3,125,956

FOLDABLE FIN Filed Oct. 10, 1961 s Sheets-Sheet 1 SVERRE KONGELBEQK INVENTOR ATTORNEYS March 1954 s. KONGELBECK FOLDABLE FIN 3 Sheets-Sheei 2 Filed Oct. 10, 1961 /,//////A il! Ii .7

SVERRE KONGELBECK INVENTOR ATTORNEYS March 1954 s. KONGELBECK FOLDABLE FIN 3 Sheets-Sheet 5 Filed 001;. 10. 1961 FIG. 6.

SVERRE KONGELBEOK INV EN TOR ATTORNEYS United States Patent 3,125,956 FOLDABLE FEN Sverre Kongelbeek, Silver Spring, Md, assignor to the United States of America as represented by the Secretar y of the Navy Filed (Bet. 10, 1961, Ser. No. 144,272 4 Claims. (Cl. 1025tl) This invention relates generally to fins for aerial missiles, and more particularly to an improved, economical to construct, foldable fin for use on service and simulated rocket missiles.

It has become common where it is necessary to conserve storage and handling space to furnish certain missiles with foldable fins, the fins being folded during storage and until just before launching. Several construc-. tions for folding fins have been proposed, among which is that shown in US. Patent No. 2,925,966, granted to the instant inventor. However, a need has existed for a structurally uncomplicated and economical foldable fin for use on missiles generally, and in particular on simulated, or dummy, missiles utilized for training purposes. The fins utilized on simulated missiles, in addition to being economical, should be designed so as to insure that they will remain folded until erection is desired, and that when erect they will be structurally stable.

It is, therefore, the principal object of this invention to provide a foldable fin so constructed as to be self-retained in folded position until erection is desired, and to be structurally stable after erection.

A further object of the invention is to provide a foldable fin that is mechanically uncomplicated and economical of construction.

Another object of this invention is to provide able fin so constructed as to be easily movable folded to an erect position.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following deailed description when considered in connection with the accompanying drawings, wherein:

FIG. 1 is a perspective of the aft end of a missile, showing four foldable fins in their erect positions;

FIG. 2 is an end elevation of the missile, showing the fins in their folded positions;

FIG. 3 is a side elevation of the rear face of one of the fins;

FIG. 4 is a cross-section on line 44 in FIG. 3, showing the construction of the latch mechanism;

FIG. 5 is an enlarged elevation, partially broken away, of a portion of the front face of a fin; and- FIG. 6 is a sectional view similar to FIG. 4, showing the fin in a folded position.

The foldable fin of the present invention includes a base portion and a body portion hingedly connected by a pin which passes through interleaved projections on the two portions. One of the projections on the body portion carries a cam surface disposed transverse to the plane of said portion, said cam surface having a pair of circumferentially spaced notches therein. The base portion contains a spring biased latch pin positioned to engage the cam surface, said pin cooperating with the two notches in the cam surface to retain the pin in either an erect or a folded position. The shape of the notch which coopcrates with the latch pin to retain the fin in a folded position is such that if a sufficient erecting force is exerted the pin will be disengaged, thus permitting erection of the fin. During the erecting, or unfolding, movement the latch pin rides upon the cam surface until the fin is fully erected, at which point it enters the second notch to secure the fin in position.

Referring now to the drawing, the aft end of a missile a foldfrom a is indicated at 2, and has four

foldable fins

4, 6, 8 and 10 attached thereto. As is best shown in FIG. 2, the fins 4 and S are constructed to fold in a clockwise direction, whereas the

fins

6 and 10 fold in a counter-clockwise direction, the fins being folded with adjacent ones overlapping.

The four fins, save for the direction in which they fold, are constructed in an identical manner, and hence only the fin 4 will be described. The fin 4 includes a root or base portion 12 and a body portion 14, the base portion having laterally projecting

flanges

16 and 18 and being secured to the missile 2 by suitable fasteners 20 which extend through openings in said flanges and engage with threaded bores within a boss 22 on the missile. The base 12 extends longitudinally of the missile, and has a pair of

upstanding projections

24 and 26 thereon which have aligned, longitudinally extending bores 28 and 3t) therethrough, respectively. Each bore is fitted with a suitable bushing 32 or 34 (FIG 5).

The base portion has a bore 36 extending normally therethrough and opening midway between the two

projections

24 and 26, the upper end 33 of said bore being enlarged to define a radial shoulder 40. A pair of aligned, vertically

elongated openings

42 and 44 extend transversely through the base portion and open into the vertical bore 36, said openings being positioned medially of the height of said base. The boss 22 on the missile has an opening 46 therein positioned to confront the vertical bore 36 (FIGS. 4 and 6). Disposed within the bore 36 and extending through opening 46 is a cylindrical sleeve 43, said sleeve being of a size to fit tightly within said bore and having an out-turned lip 50 which is received within the enlarged bore portion 38 and which rests upon shoulder 46 Disposed within sleeve 48 is a latch pin 52, said pin having a rounded, chisel-shaped upper end 54 and a transverse slot 56 extending therethrough below said upper end (FIG. 4). The sleeve 48 has a pair of confronting, elongated vertical guide slots 58 and 69 therein, and a guide pin 62 is received within a transverse bore in the pin 52 below the slot 56 and extends through said slots 53 and 6% The guide pin functions to limit the extent to which the latch pin may slide within its housing, and to prohibit relative rotation therebetween. Positioned between the lower end of the latch pin and the lower end of the sleeve is a coil spring 62, which is retained in position by a washer 64 and an inturned lip 66 on the sleeve. The transverse slot 56 in the latch pin and

slots

58 and 6%? in the sleeve are positioned to confront

openings

42 and 44, and are so dimensioned that a pointedtool 63 (shown by phantom lines in FIG. 4) may be inserted therethrough to depress the latch pin against the force of spring 62.

The body portion 14 of the fin has a pair of

projections

70 and 72 thereon which, together with the lower, trailing part 74 of the body 14, define a pair of notches 76 and 73 of a size to freely receive the

projections

24 and 26. The projection 70 and the trailing part 74 of the fin body have flat end faces 80 and 32 thereon, which are presented to the

notches

76 and 78. Similarly, the

projections

24 and 26 have flat end faces S3 and thereon, the distance measured between said

faces

83 and 85 being slightly less than the distance between the faces 8% and 82. The notch defined between the

projections

24 and 26 is of substantially greater width than is the projection 72 which is received therein. The

projections

70 and 72 and the trailing edge 74 have, respectively, aligned

bores

34, 86 and 88 therein. To assemble the body portion 14 of the fin to the base portion 12, the

projections

24 and 26 and the

projections

70 and 72 are interleaved, with the

bores

84, 28, 86, 30 and 88 aligned. A pin 90 is then inserted through said bores, and is retained in position by a key 92 which passes through aligned openings in said pin and fin portion 74. The

notches

76 and 78 are of a height sufiicient to permit the fin to easily fold.

The projection 72 has a rounded cam surface 94 thereon, the radius of which (measured from the center of bolt 90) decreases progressively from a maximum at the upper end 96 thereof to a minimum at its lower end 98 (FIG. 4). The cam surface has a shallow, rounded groove 100 near its upper end, and a deep, wedge-shaped groove 102 adjacent its lower end. The rear wall of groove 102 is defined by a rounded boss 104 on the rear face of projection 72, which boss projects radially substantially further than the bottom 98 of cam surface 94 to define an engagement face 106. The groove 1% is so positioned that it will confront the tip 54 of latch pin 52 when the fin body 14 is in its folded position. Similarly, the groove 102 is so positioned that it will confront the tip 54 when the body 14 is in its erect position.

In operation, the fin body 14 is initially in its folded position (FIGS. 2 and 6), with the rounded tip 54 of latch pin 52 received within rounded groove 100. The force of spring 62 on the pin 52 is sufiicient to retain the fin in this folded condition until a substantial erect ing force is exerted thereon, whereupon the rounded surfaces of tip 54 and groove 100 will cooperate to depress the pin 52, thus releasing the fin body 14 for rotation about bolt 90. While the fin body is rotating to its erect position the tip 54 rides upon cam surface 94. The speed of erection of the fin is normally exceedingly fast (erection being normally accomplished by powerful, mechanical mechanisms such as that shown in US. Patent No. 2,977,880) and it is therefore desirable to overcome the inertia of pin 52 as soon as possible, preferably before it must move into groove 102. The declining radius of cam surface 94 accomplishes this by permitting the pin to move upwardly a small amount during rotation of the fin body 14. The declining radius also serves a more important purpose, in that it insures that a substantial portion of the pin will be presented for engagement with engagement surface 106.

As the fin becomes erect, engagement surface 106 on boss 104 engages the latch pin 52, thus stopping rotational movement of the former. Immediately upon erection of the fin body, latch pin 52 moves upwardly into notch 102, the tapered walls of the latter cooperating with the rounded, wedge-shaped tip 54 to tightly lock the fin in its erect position. To fold the fin the tool 68 is utilized to depress pin 52, after which the body portion 14- may be folded down.

It is to be understood that while only one retaining pin and cam surface assembly is shown, in certain instances it may be desirable to employ two or more such assemblies. This might be necessary for large and bulky fins because of strength considerations, and accordingly the use of a plurality of such assemblies is considered within the scope of the invention.

Obviously, many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A foldable fin for an aerial vehicle, including a base portion having a plurality of upwardly extending, spaced projections thereon, a body portion having a plurality of downwardly extending, spaced projections thereon, said projections on said base and said body portions being interleaved and having aligned bores extending therethrough, a pin disposed within said bores for hingedly connecting said two portions, a generally arcuate convex cam surface on at least one of said projections on said body portion, said cam surface being disposed normally to said body portion and said base portion and having a pair of spaced grooves therein, one of said grooves being defined by rounded surfaces and being disposed near the top of said cam surface and the other of said grooves having a wedge shape and being disposed at the bottom of said cam surface, and a spring-biased detent means for each cam surface, said detent means being disposed within said base portion and positioned to engage said cam surface, said detent means being engageable with said one of said grooves for retaining said body portion in a folded position against relatively small erecting forces, and being engageable with said other of said grooves for securing said body portion in position after it has been erected.

2. A foldable fin as recited in claim 1, wherein the radius of said cam surface decreases progressively from said one groove toward said other of said grooves.

3. A foldable fin as recited in claim 1, wherein said base portion has a vertical bore therein for each detent means, and wherein said detent means includes a cylindrical sleeve disposed within said vertical bore, a latch pin disposed within said sleeve, a coil spring disposed within said sleeve in a position to urge said latch pin upwardly, and means attached to said latch pin and cooperable with said sleeve for restraining the movement of said latch pin.

4. A foldable fin as recited in claim 3, wherein additionally said base portion has elongated openings therein positioned to confront each said vertical bore, and wherein said latch pin and said sleeve have confronting slots therein positioned to confront said openings, whereby a tool may be inserted into said slot in said latch pin for depressing it against the force of said spring.

References Cited in the file of this patent UNITED STATES PATENTS 2,797,658 Doty July 2, 1957 2,858,765 Startzell Nov. 4, 1958 2,925,966 Kongelbeck Feb. 23, 1960 3,031,967 Jasse May 1, 1962