Apparatus for unfolding and fixing missile fins

An improved apparatus for unfolding and fixing missile fins which is capable of automatically unfolding the fins of a missile when launching the missile loaded in a missile launch tube, in which the fins of the missile are folded, which includes a plurality of fins fixed to a missile body, a plurality of rotation fins rotatably supported by the fixed fin, rotation stoppers elastically supported in the direction the rotation fins are unfolded, and unfolding and fixing member forwardly and rearwardly movable with respect to the fixed fins and each having a straight movement stopper elastically supported toward the rotation stopper.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus for unfolding and fixing 
missile fins, and in particular to an improved apparatus for unfolding and 
fixing missile fins which is capable of automatically unfolding the fins 
of a missile when launching the missile loaded in a missile launch tube, 
in which the fins of the missile are folded. 
2. Description of the Conventional Art 
Generally, the missile loaded in a missile launch tube is supported by a 
guide rail of the missile launch tube. After the missile is launched from 
the missile launch tube, the fins thereof are rapidly unfolded and fixed, 
so that the flying of the missile is guided by the fins fixed to the outer 
surface thereof. 
However, since it is necessary to reduce the weight of the missile and to 
minimize the drag force of the missile for a small-sized missile, the 
parts for unfolding and fixing the fins of the missile should be 
substantially embedded within the body, and the fins of the missile must 
have a predetermined strength against the air pressure applied thereto. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the present invention to provide an 
improved apparatus for unfolding and fixing missile fins which overcomes 
the problems encountered in the conventional apparatus for unfolding and 
fixing missile fins. 
It is another object of the present invention to provide an apparatus for 
unfolding and fixing missile fins which is capable of automatically and 
rapidly unfolding the fins of a missile when launching the missile loaded 
in a missile launch tube, in which the fins of the missile are folded. 
To achieve the above objects, there is provided an apparatus for unfolding 
and fixing missile fins which includes a plurality of fins fixed to a 
missile body, a plurality of rotation fins rotatably supported by the 
fixed fin, rotation stoppers elastically supported in the direction the 
rotation fins are unfolded, and unfolding and fixing member forwardly and 
rearwardly movable with respect to the fixed fins and each having a 
straight movement stopper elastically supported toward the rotation 
stopper.

DETAILED DESCRIPTION OF THE INVENTION 
The construction of an apparatus for unfolding and fixing the fins of a 
missile according to the present invention will now be described with 
reference to the accompanying drawings. 
FIG. 1 is a perspective view showing an apparatus for unfolding and fixing 
missile fins according to the present invention. As shown therein, the 
apparatus therefor includes fins 10 fixed to the outer surface of a 
missile body 1, rotation fins 20 rotatably engaged to the fins 10, and a 
unfolding and fixing member 30 for fixing and automatically unfolding the 
rotation fins 20 with respect to the fixed fins 10. 
Four fins 10 are radially fixed to the outer surface of the missile body 1 
and are spaced-apart at a regular interval. 
The rotation fins 20 are rotatable by a hinge shaft 16 with respect to the 
fixed fin 10. 
Here, the fin 10 includes a hinge end portion 11 having a hinge groove 11a 
into which the hinge shaft 16 is inserted, a rear hinge portion 12 having 
a space 12a through which the hinge shaft 16 passes through, and an 
intermediate cut-away portion 13 and a rear side cut-away portion 14 
formed between the hinge portions 11 and 12 and in the end portion of the 
rear hinge portion 12, respectively. 
A spar 15 is formed in the inner portion of the fixed fin 10 for fixing the 
fins 10 to the missile body 1. 
The rotation fins 20 include an intermediate hinge 21, which matches with 
the intermediate cut-away portion 13, having a space 21a through which the 
hinge shaft 16 passes, and a rear support portion 22, which matches with 
the rear cut-away portion 14, having a space 22a through which the hinge 
shaft 16 passes and a hinge hole 22b into which the end portion of the 
hinge shaft 16 is inserted and supported thereby. 
The unfolding and fixing member 30 includes a torsion spring 31 formed in 
the intermediate cut-away portion 13 of the fixed fin 10 and wound onto 
the hinge shaft 16 for elastically supporting the rotation fins 20 in the 
unfolding direction of the fins, a rotation stopper 32 inserted within the 
intermediate hinge portion 21 of the rotation fin 20 and being rotatably 
together with the rotation fin 20, and a straight movement stopper 35 
inserted within the rear hinge portion 12 of the fixed fin 10 which is 
slidable in the forward and backward directions and is elastically 
supported therein in order for the unfolding state of the rotation fin 20 
engaged with the rotation stopper 32 to be secured when the rotation fin 
20 is unfolded. 
The hinge shaft 16 is inserted into the hinge hole 22b formed in the rear 
hinge portion 22 of the rotation fin 20 from its rear portion to its front 
portion, with the front portion thereof being supported by the hinge 
groove 11a formed in the hinge end portion 11 of the fixed fin 10, and 
with the rear portion thereof being supported by the hinge hole 22b. 
The torsion spring 31 is inserted within the space 21a of the intermediate 
hinge portion 21 of the rotation fin 20 before the hinge shaft 16 is 
inserted, and the torsion spring 31 is wound onto the hinge shaft 16 when 
the hinge shaft 16 is inserted. 
The front end portion 31a of the torsion spring 31 is inserted into the 
spring fixing groove 11b formed in the outer surface of the front end of 
the hinge end portion 11 of the fixed fin 10 in the radial direction, and 
the rear portion thereof is inserted into the fixing groove 32a formed in 
the outer surface of the rotation stopper 32. 
Here, the outer portion of the cut-away spring fixing groove 11b is open in 
order for the front end portion 31a of the torsion spring 31 to be 
inserted therethrough, and the outer portion of the spring fixing groove 
32a is open in order for the rear portion 31b of the torsion spring 31 to 
be inserted therethrough. The spring fixing groove 11b is formed just 
below a root chord 20a of the rotation fin 20 so as to prevent any 
interference of air flow when the missile flies in a state that the fins 
are unfolded. 
A pair of engaging protrusions 33, one of which is shown in FIG. 1, are 
formed in the rear portion of the rotation stopper 32, and an engaging 
groove 36 to which the engaging protrusion 33 is engaged is formed in the 
front end surface of the straight movement stopper 35, and the engaging 
protrusion 33 contacts with the front end portion of the straight movement 
stopper 35 in a state that the rotation fin 20 is folded, and the rotation 
fin 20 is engaged to the engaging groove 36, and maintains a state that 
the rotation fin 20 is unfolded. 
The engaging protrusion 33 and the engaging groove 36 are disposed in a 
position where there is a 180.degree. phase difference therebetween, so 
the range of the rotation angle of the rotation fin 20 exceeds 90.degree.. 
Here, the engaging protrusion 33 is formed in the rotation stopper 32, and 
the engaging groove 36 is formed in the straight movement stopper 35. 
However, the installations thereof are not limited thereto. Namely, the 
positions therebetween may be changed. 
The rotation stopper 32 is inserted into the intermediate hinge portion 21 
of the rotation fin 20, and is integral with the intermediate hinge 
portion 21 and the rotation stopper 32 by inserting the pin hole 21b 
formed in the wall of the intermediate hinge portion 21 and the pin hole 
32b formed in the wall of the rotation stopper 32. 
The straight movement stopper 35 is slidable within the space 12a formed in 
the rear hinge portion 12 of the fixed fin 10, and is forwardly and 
elastically supported by a compression spring. 
The compression strength of a compression spring 37 is greater than the 
compression strength of the torsion spring 31. 
The straight movement stopper 35 is forwardly and backwardly movable, with 
the height of the engaging groove 36 and its circumferential surface being 
constant. A key guide groove 35a is radially formed in the inner portion 
of the wall of the straight movement stopper 35, and a square-shaped key 
38 is inserted into the key guide groove 35a through the key through hole 
12b formed in the inner portion of the fixed fin 10, so that the straight 
movement stopper 35 becomes linearly, forwardly, rearwardly movable. 
A protrusion guide groove 12d, by which the engaging protrusion 33 is 
guided, is formed in an outer portion of the rear hinge portion 12 in the 
radial direction. The protrusion guide groove 12d is positioned just below 
the root chord 20a of the rotation fin 20 in order for the air flow 
resistance to be minimized when the missile flies, with the fins of the 
missile being unfolded. 
A tool guide hole 12c is formed in a portion of the wall of the rear hinge 
portion 12, and a tool insertion hole 35b is formed in an outer portion of 
the straight movement stopper 35 in order for the straight movement 
stopper 35 to be backwardly moved by inserting a tool 39 into the tool 
insertion hole 34b and by backwardly pulling the same to overcome the 
elastic force of the compression spring 37. 
In FIG. 2, reference numeral 2 denotes a missile launch tube. 
The order of the assembling of an apparatus for unfolding and fixing 
missile fins according to the present invention will now be explained. 
First, the straight movement stopper 35 is inserted into the space 12a of 
the rear hinge portion 12 of the fixed fin 10, and the inner end portion 
of the square-shaped key 38 is inserted into the key guide groove 35a of 
the straight movement stopper 35 by inserting the square-shaped key 38 
through the key through hole 12b, so that only lineal movement of the 
straight movement stopper 35 is made. 
The torsion spring 31 and the rotation stopper 32 are inserted into the 
space 21a of the intermediate hinge portion 21 of the rotation fin 20, and 
the front end portion 31a of the torsion spring 31 is inserted into the 
spring fixing groove 11b of the front end portion 11, and the rear portion 
31b thereof is inserted into the spring fixing groove 32a of the rotation 
stopper 32, and the fixing pin 34 is inserted into the pin hole 21b formed 
in the intermediate hinge portion 21 and is inserted into the pin hole 32b 
of the rotation stopper 32, whereby the rotation stopper 32 is fixed to 
the intermediate hinge portion 21 of the rotation fin 20. 
In a state that the compression spring 37 is inserted into the space 22a of 
the rear hinge portion 22 of the rotation fin 20, the rotation fin 20 is 
fitted to the intermediate cut-away portion 13 of the fixed fin 10, and 
the rear hinge portion 22 is fitted to the rear cut-away portion 14 of the 
fixed fin 10, then hinge shaft 16 is inserted into the rear cut-away 
portion 14 of the fixed fin 10 through the hinge hole 22b of the rear 
hinge portion 22 of the rotation fin 20. 
Here, since the engaging protrusion 33 of the rotation stopper 32 is 
protruded from the rear portion of the intermediate hinge portion 21 of 
the rotation fin 20, and the engaging protrusion 33 is guided by the 
protrusion guide groove 12d formed in the rear hinge portion 12 of the 
fixed fin 10, the engaging protrusion 33 is not interfered by the rear 
hinge portion 12. 
Meanwhile, since the straight movement stopper 35 is forwardly and 
elastically supported by the compression spring 37, when the rotation 
stopper 32 is fitted, there occurs an interference therebetween. In 
addition, the straight movement stopper 35 is backwardly moved by 
inserting the tool 39 into the tool insertion hole 35b of the straight 
movement stopper 35 through the tool guide hole 12c and by backwardly 
pulling the same. As a result, the rotation stopper 32 is not interfered 
by the straight movement stopper 35. 
The hinge shaft 16 is inserted into the hinge groove 11a, with its front 
end portion being formed in the front end hinge portion 11, through the 
compression spring 37, the straight movement stopper 35, the rotation 
stopper 32, and the torsion spring 31, and the rear portion thereof is 
supported by the hinge hole 22b of the rear hinge portion 22. 
In the above-mentioned state, the rotation stopper 32 is inserted into the 
intermediate hinge portion 21 of the rotation fin 20, and the rotation 
stopper 32 is supported by the key 38 inserted into the key through hole 
12b of the fixed fin 10, and none of the parts and portions are protruded 
toward the outside. In addition, since the compression spring 37 is 
disposed in the rear portion of the rotation fin 20 for elastically 
supporting the straight movement stopper 35, the fin is shaped as a 
streamline which is characterized to minimize the air flow resistance. 
In a state that the assembling process is finished, when rotating and 
folding the rotation fin 20, the tool 39 is inserted into the tool guide 
hole 12c formed in the rear hinge portion 12 of the fixed fin 10, and the 
front end portion thereof is fitted to the tool insertion hole 35b of the 
straight movement stopper 35. Thereafter, the straight movement stopper 35 
is backwardly moved when backwardly pulling the tool 39, and the engaging 
groove 36 does not interfere with the engaging protrusion 33 of the 
rotation stopper 32. 
In the above-described state, when rotating the rotation fin 20, as shown 
in FIG. 3A, the front end portion of the engaging protrusion 33 of the 
rotation stopper 32 comes into contact with the front end surface of the 
straight movement stopper 35. 
Here, when rotating and folding the rotation fin 20, the torsion spring 31 
is twisted, with the rear portion 31b thereof being fixed to the rotation 
stopper 32 integrally engaged with the rotation fin 20. Therefore, the 
torsion spring 31 becomes free, stores a torsion recovering force as 
indicated by the full line in FIG. 1, and becomes the state as indicated 
by the virtual line shown in FIG. 1. This torsion recovering force serves 
to unfold the rotation fin 20, with the force being applied thereto 
through the rotation stopper 32. 
In a state that the rotation fin 20 is folded, when loading the missile 
body 1 into the missile launch tube 2, the end portion of the rotation fin 
20 contacts with the inner surface of the missile launch tube 2, and the 
rotation fin 20 is not unfolded by the torsion recovering force of the 
torsion spring 31. 
When the missile is launched from the missile launch tube 2, the end 
portion of the rotation fin 20 is escaped from the inner surface of the 
missile launch tube 2 at the moment when the fin portion is took off from 
the front end portion of the missile launch tube 2, so that the rotation 
fin 20 is rotated by the torsion recovering force of the torsion spring 
31, and is unfolded as shown in FIGS. 4A and 4B. 
Here, the fin unfolding process will now be explained in more detail. The 
rotation stopper 32 is rotated in the unfolding direction about the hinge 
shaft 16 by the torsion recovering force of the torsion spring 31 at the 
moment when the rotation fin 20 is escaped from the front end portion of 
the missile launch tube 2, and the rotation fin 20 fixed to the rotation 
stopper 32 by the fixing pin 34 is rotated. 
Here, when the rotation stopper 32 is rotated in the unfolding direction, 
the front end portion of the engaging protrusion 33 contacts with the 
front end portion of the straight movement stopper 35, and reaches the 
engaging groove 36 of the straight movement stopper 35, the straight 
movement stopper 35 forwards by the compression spring 37. Thereafter, the 
engaging protrusion 33 of the rotation stopper 32 is engaged to the 
engaging groove 36 of the straight movement stopper 35, and is not moved. 
As a result, the rotation fin 20 integral with the rotation stopper 32 is 
not moved. 
In a state that the rotation fin 20 is unfolded, since the torsion 
recovering force of the straight movement stopper 35 of the torsion spring 
31 is widely applied over the square-shaped key 38 and the key through 
hole 12b of the fixed fin 10, it is possible fabricate a compact size of 
the system and an apparatus having a high strength. 
Thereafter, the missile flies, with the fins thereof being unfolded. Since 
the rotation fin 20 is engaged to the engaging groove 36 of the straight 
movement stopper 35 in which the engaging protrusion 33 of the rotation 
stopper 32 is forwardly and elastically supported by the compression 
spring 37, the rotation fin 20 is not folded during the flight. 
Since the spring fixing groove 11b having the portion opened in the radial 
direction of the fixed fin 10 and the protrusion guide groove 12d are 
positioned just below the root chord 20a of the rotation fin 20, it is 
possible to minimize the air flow resistance. 
Although the preferred embodiments of the present invention have been 
disclosed for illustrative purposes, those skilled in the art will 
appreciate that various modifications, additions and substitutions are 
possible, without departing from the scope and spirit of the invention as 
recited in the accompanying claims.