Self-propelled fin stabilized projectiles and launchers therefor

Abstract

An improved, self-propelled fin stabilized projectile is disclosed which ludes a generally cylindrical body, a finned unit mounted thereon for relative rotational movement with respect thereto, the cylindrical body having a plurality of rigid studs symmetrically spaced about and affixed to the periphery of the body and a plurality of rigid studs mounted for rotation relative to the body. The distal end of each of the studs is adjacent to the body. The fin unit includes a plurality of fins symmetrically spaced about the periphery of the body and extending outwardly therefrom so that the distal end of the fins is remote from the body, the fin unit having a plurality of rigid studs symmetrically spaced about the periphery of the body, the distal end of which is adjacent to the body. A projectile launcher also is disclosed which includes a partially cylindrical first rail having a curvilinear surface spanning an arc of less than 180.degree. and having a groove obliquely oriented with respect to the projectile longitudinal axis to receive the projectile body's fixed studs. The launcher also includes a pair of second rails each having a rectilinear groove parallel to the projectile's body axis for receiving the projectile fin unit's studs and the body's relatively rotatable studs.

Parent Case Text

BACKGROUND

This is a continuation-in-part of patent application Ser. No. 236,612 filed Mar. 21, 1973, now abandoned.

Description

This invention relates to improved, self-propelled fin stabilized projectiles and, more particularly, to rockets and their launchers having improved and simplified mechanical means for guiding the rocket during launching so that it leaves its launcher with a desired translational trajectory and a desirable slow rotation.

While unguided rocket projectiles have many desirable features, one particular problem of great concern is their relative flight inaccuracy resulting in a substantial dispersion of a salva of rockets. There are two primary systems used for improving the accuracy of unguided rocket projectiles. One system is spin or gyroscopic stabilization wherein a rapidly spinning projectile resists being disturbed and maintains the orientation of its longitudinal (spin) axis. Rotation of the projectile also tends to cancel or average out geometrical irregularities and mass imbalance. These physical irregularities commonly exist for various reasons, including problems inherent in mass producing weapons requiring absolute symmetry about a longitudinal axis, nozzle misalignment, variation or shift in center of gravity due to uneven burning of the propellant and other similar reasons. However, gyroscopic stabilization causes most rocket projectiles to tend to maintain a fixed attitude throughout its flight thereby preventing it from orienting itself during the flight of the projectile so that its longitudinal axis remains tangential to its trajectory. The result of this fixed attitude is an increase of drag resulting in reduced range and an increase in dispersion in the direction of flght thereby lessening the projectile's accuracy. Furthermore, external forces on the projectile, such as lateral wind forces and gravity produce gyroscopic precession which also adversely affects flight accuracy. While the problems of gyroscopic stabilization can be overcome, the resultant rocket projectile will have several limitations, including a narrow flight speed range and a relatively large weight requiring a launcher capable of handling the heavy projectile. Consequently, such stabilization is unsuitable for small and medium caliber rocket projectiles.

A further problem involved with spin stabilization of rocket projectiles is the added static friction caused by the projectile rotating means. Rocket powered projectiles have relatively low static thrust and any increase in static friction which has to be overcome during launching of rocket would seriously adversely affect the ultimate range of the rocket projectile.

A second system for controlling the flight of a rocket projectile is fin stabilization in which the rocket projectile is stabilized during flight by aerodynamic forces provided by relative movement of air over the rocket projectile and its guidance fins. A fin stabilized rocket maintains its longitudinal axis tangential to its flight trajectory; however, fin stabilization does not compensate for geometrical or mass asymmetry resulting in dispersion and reduced accuracy.

Accordingly, it is an objective of this invention to provide an unguided rocket projectile having substantially improved flight accuracy without sacrifice of firing range and which is relatively inexpensive to manufacture.

It is a further objective of this invention to provide a rocket projectile and launcher therefor which enables a plurality of rocket projectiles to be fired from a launcher of minimal size without loss of accuracy.

Additional objectives and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE INVENTION

To achieve the foregoing objectives and in accordance with the purpose of the invention, as embodied and broadly described herein, the self-propelled, fin stabilized projectile of this invention comprises an elongated, generally cylindrical projectile body, a plurality of rigid first studs symmetrically spaced about the periphery of the projectile body and affixed thereto to prevent relative movement between the first studs and the body, the distal end of the first studs being adjacent to the body, a fin unit including a plurality of fins symmetrically spaced about the periphery of the body and extending outwardly therefrom such that the distal end of the fins is remote from the body, the fin unit being mounted on the body for rotational movement relative to the body about the longitudinal axis of the body, the fin unit being mounted on the body for rotational movement relative to the body about the longitudinal axis of the body, the fin unit having a plurality of rigid second studs symmetrically spaced about the periphery of the body, the distal end of the second studs being adjacent to the body and a plurality of rigid third studs symmetrically spaced about the periphery of the body and mounted for rotational movement relative to the body about the body's longitudinal axis, the distal end of the third studs being adjacent to the body.

This invention further comprises a projectile launcher having the above described projectile placed therein, the launcher including a partially cylindrical first rail having a longitudinal axis parallel to the longitudinal axis of the projectile body and having a curvilinear surface spanning an arc of less than 180.degree., the first rail including a first groove obliquely oriented with respect to the projectile longitudinal axis, the first studs of the projectile being received within the first groove and coacting therewith to effect rotation of the projectile body about its longitudinal axis when the projectile is propelled relative to the launcher, and at least two equally spaced apart second rails each having a rectilinear groove extending parallel to the projectile body's longitudinal axis, the second and third studs of the projectile's fin unit being received within the rectilinear groove and coacting therewith to prevent rotation of the fin unit relative to the launcher during propulsion of the projectile body relative to the launcher.

The invention consists in the novel parts, constructions, arrangements, combinations and improvements shown and described. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate preferred embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Of the drawings:

FIG. 1 is a side view, partially cutaway, of a self-propelled fin stabilized projectile formed in accordance with one embodiment of this invention.

FIG. 2 is a schematic illustration of an end view of a multiple projectile launcher for launching a plurality of projectiles illustrated in FIG. 1.

FIG. 3 is a sectional view of one of the launchers of FIG. 2 having a projectile in place for launching.

FIG. 4 is an enlarged perspective view of a curvilinear launching rail which forms a part of the launcher of FIG. 3.

FIG. 5 is a side view of a self-propelled fin stabilized projectile formed in accordance with a second embodiment of this invention.

DETAILED DESCRIPTION OF THE INVENTION

SELF-PROPELLED PROJECTILE

Reference will now be made in detail to the present preferred embodiments of the invention, two examples of which are illustrated in the accompanying drawings.

Referring to FIGS. 1-4, there is illustrated a self-propelled fin stabilized projectile and a launcher for the projectile.

In accordance with the invention, a self-propelled fin stabilized projectile includes a generally cylindrical body and a fin unit mounted to permit rotational movement between the projectile body and fin unit. As here embodied, a projectile 10 is formed with a generally cylindrical body 12 having a conical forward portion or nose 14 and a finned unit 16. While the finned unit 16 may be located at any one of several locations along the length of the projectile body 12, preferably the finned unit 16 forms the tail of the projectile 10. The nose 14, depending upon the ultimate use of the projectile 10, may carry a warhead (not shown) of conventional construction. The cylindrical body 12 houses a conventional rocket propellant, such as a solid propellant grain (not shown) and a conventional convergent-divergent nozzle 18 is mounted at the aft end of the projectile.

In this first embodiment, the finned tail unit 16 is formed of a cylindrical sleeve 20 having a plurality of aerodynamic fins 22 extending therefrom and equally spaced about the sleeve 20. Large span fins having a large surface area and wherein the distal end of the fins is remote from the projectile body 12 are used in order to ensure a sufficient stabilization as soon as the projectile leaves its launcher. Preferably, the total fin span is more than twice the diameter of the projectile body 12. In the embodiment illustrated, the fin unit 16 includes four fins 22 spaced apart by 90.degree.. The fin unit 16 is mounted to permit rotation of the projectile body 12 relative to the fin unit. One method of accomplishing this rotational mounting is to journal the fin sleeve 20 onto a reduced portion 24 of the projectile body 12. If desirable, bearing means (not shown) may be employed to facilitate free rotation of the projectile body 12 relative to the fin unit 16. The finned tail unit 16, being very light and freely rotating about the projectile body 12, easily and quickly turns to present the maximum fin surface when subjected to cross winds.

In accordance with the invention, the projectile body 12 is provided with a plurality of small rigid projections or guide studs 28, preferably cylindrical, symmetrically spaced about the periphery of the body 12 and affixed to the body 12 to prevent relative movement between the studs 28 and the body 12. One method of attaching the studs 28 to the body is to press fit the studs 28 into perforations which have a diameter slightly smaller than the stud diameter for a firm force fit. In order to minimize drag, the studs 28 are very small in diameter and the distal end 30 of the studs is adjacent to the projectile body; however, to facilitate illustrating the invention, the studs 28 shown in the drawings are magnified. For example, with a projectile body having a 138 mm caliber and a length of 2m, the distance between the distal end 30 of the studs 28 and the outer surface of the body 12 is 8mm, while the stud diameter is 6mm. In order to provide symmetry for the projectile body, at least two studs 28 must be employed and, in that case, they are spaced apart by 180.degree.. However, it is obvious that more than two studs may be used provided they are disposed at equal intervals about the periphery of the projectile body 12, such as 90.degree. for four studs or 120.degree. for three studs.

In accordance with the invention, a plurality of rigid projections or guide studs 32, preferably cylindrical, also are symmetrically spaced about the fin unit sleeve 20 and fixedly attached thereto to prevent relative movement between the studs 32 and the sleeve 20. As was discussed above with respect to the studs 28, at least two studs 32 must be mounted on the fin unit for aerodynamic symmetry and the studs also must be small to minimize drag. The size of the fin unit studs 32 preferably are the same as the projectile body studs 28.

A third group of guide studs 34 also is provided, with the studs being equally spaced about the periphery of the projectile body and positioned on the side of the projectile's center of gravity opposite that of the fin unit 16. In the embodiment illustrated, the studs 34 are spaced forwardly from the fin unit 16, at least slightly ahead of the projectile's center of gravity. The third group of studs 34 is mounted for relative rotational movement with respect to the projectile body 12. The studs 34 may be fixedly mounted, such as by a force fit, on an annular collar 36 which is journalled onto the projectile body 12 to permit free rotation therebetween.

The projectile body 12 may be formed of seamless cold drawn steel which is swaged at its tail end to receive the fin tail unit 16. An annular depression can also be swaged into the body to receive the stud collar 36. The fin tail unit preferably is formed of a light alloy casting in order to minimize its weight while still providing aerodynamic guidance. All of the studs 28, 32 and 34 preferably are steel with the studs 32 being attached to the fin sleeve 20 by molding the sleeve 20 around the base of the studs.

LAUNCHER

Further in accordance with this invention, there is provided a launcher for accurately firing the projectile 10. The design of the projectile 10 and the launcher are particularly suited for launching multiple projectiles while minimizing the size of the multiple rocket launcher. FIG. 2 illustrates a multiple rocket launcher 50 formed of a plurality of individual launchers 52, one of which is illustrated in FIG. 3 and is shown with a projectile 10 in position for launching. The launcher 52 essentially includes a partially cylindrical launching rail 54 having a curvilinear surface 56 which conforms to the periphery of the projectile 10. The maximum arc spanned by the curvilinear surface 56 is determined by the number of fins 22 borne by the projectile 10, the surface 56 being designed to reside between two adjacent fins 22. For a four finned projectile 10, wherein the fins are spaced apart 90.degree., theoretically the arc span for the surface 56 may approach 90.degree.. However, to accommodate fin thickness and insure complete clearance between the rail 54 and the fins, the curvilinear surface 56 preferably spans approximately 50.degree.. If desired, more than one cylindrical rail 54 could be used. For example, a second such rail (not shown) could be mounted diametrically opposite to the rail 54 shown in FIG. 3.

As here embodied, a groove 58 is provided in the curvilinear surface 56 having a width sized to receive the studs 28 affixed to the projectile body 12. The groove 58 is obliquely oriented with respect to the longitudinal axis of the projectile 10 in order to rotate the projectile body 12 as the projectile is launched as is described in detail below. Preferably, the groove 58 takes the form of a portion of a helix as can be best seen in FIG. 4. Because rocket projectiles have a constant acceleration and because the groove 58 has a relatively constant slope, rotation is imparted to the projectile 10 at a constant acceleration. Since the studs will not experience shocks their size can be minimized thereby minimizing drag and friction.

As here embodied, the launcher 52 also includes two additional launching rails 60, 62 located on diametrically opposed sides of the projectile 10 and very close to the projectile body 12 to suppress projectile vibrations. The launching rails 60, 62 are formed with rectilinear grooves 64, 66, respectively, sized to receive the studs 32 of the finned tail unit 16 and the third group of studs 34. The rectilinear grooves 64, 66 are aligned parallel to the longitudinal axis of the projectile 10.

In a preferred form of launcher 52 the rectilinear launching rails 60, 62 are angularly offset from the cylindrical launching rail 54 to insure no interference between the fin tail unit studs 32 and the cylindrical rail 54. As can be seen in FIGS. 2 and 3 the launcher 52 is relatively open (as compared with launch tubes) to eliminate the effect of the inversion of flow of burned gases at the exit end of the launcher as the projectile leaves the launcher, which is a substantial problem with launch tubes.

Upon ignition of the projectile propellant, the projectile 10 is propelled along the length of the launcher 52. The rectilinear grooves 64, 66 provide axial stability and guide the projectile during launching and prevent rotation of the finned tail unit 16 relative to the launcher 52. The longitudinally spaced apart group of studs 32, 34 in the launching rails 60, 62 support the projectile 10 so that the projectile body 12 does not rest on and slide along the surface 56 of launching rail 54 which would involve substantial friction. The shape and small size of the studs, in addition to producing minimum aerodynamic drag also minimize the launcher sliding friction. However, as a safety feature, if one of the studs 32, 34 break the projectile body 12 will rest on the launcher rail 54 and can still be launched with reasonable accuracy, albeit not as accurately as if all of the studs 32, 34 are in the grooves 64, 66. The partially cylindrical rail 54, in which the rigid studs 28 firmly affixed to the projectile body 12 reside and with which they coact causes the projectile body 12 to rotate about its longitudinal axis relative to the launcher 52 and, hence, relative to the fin tail unit 16. The particular shape and angular orientation of the groove 54 controls, at least partially, the ultimate speed of rotation of the projectile body 12. For example, for a given launch velocity, the angular orientation of the groove 58 relative to the longitudinal axis of the projectile 10 determines the speed of rotation of the body 12. Alternatively, for a particular groove orientation, the rotational speed of the body 12 can be modified by varying the projectile launch velocity.

In order to avoid the deleterious effects of gyroscopic stabilization while obtaining the benefits afforded by rotating the projectile body, namely to equalize mass or geometrical irregularities and asymmetries, the projectile body desirably is rotated at a relatively slow speed, preferably on the order of 90 to 270 r.p.m., as compared to gyroscopic stabilization rates of 10,000 r.p.m. and higher. Satisfactory results have been obtained with a body rotation of 150 r.p.m. when a projectile weighing 52 kg and having a length of 2m and caliber of 138mm is launched at 33 meters per second. To accomplish this slow rotational speed, the angle at which the helical groove 58 crosses a longitudinal element of the partial cylindrical curvature of the internal surface 56 of the launch rail 54 is small, preferably within the range of 1.degree. to 3.degree.. For a 30 meter per second launch velocity the rotational speed for a 1.degree. groove angle is 90 r.p.m. and for a 3.degree. groove angle the rotational speed is 270 r.p.m.

Because of the initial thrust developed by rocket motors is relatively low, it is desirable to reduce the static friction which must be overcome to a minimum. Since the helical groove 58 provides a retardant force in the longitudinal direction of propulsion of the projectile 10 in order to provide a force for effecting rotation of the projectile body, a preferred form of launching rail 54, shown in FIG. 4, provides an initial portion 66 of the groove 58 which is rectilinear and does not have the added resistance force in the axial direction which is provided by the helical portion 68. This permits the rocket motor to overcome the static friction and begin propulsion of the projectile 10 before the helical portion 68 of the groove 58 becomes effective for imparting rotation to the projectile. Similarly, instead of forming the groove 58 in the form of a partial helix, the groove can be formed to gradually increase in angularity in order to gradually impart rotation to the projectile as the projectile is propelled and attains sufficient inertia to help overcome the braking effect caused by the helical portion of the groove 58. Preferably, the projectile body 12 is brought to its cruise rotating speed slightly before leaving the launcher 52.

Further in accordance with the invention, the multiple pad launcher 50 is formed with the individual launchers 52 positioned in overlapping formation to minimize the total cross-sectional area required for a plurality of launchers. In other words, for a fixed cross-sectional area, more launchers 52 and projectiles 10 can be accommodated by virtue of the overlapping configuration than if the launchers were horizontally and vertically aligned. Furthermore, the overlapping configuration permits the individual launcher's 52 structural members to serve also as supports for adjacent individual launchers rather than requiring additional structural members. This overlapping configuration of launchers suitable for launching finned rockets which are provided with rotational motion is made possible by the construction of the projectile 10 and the cooperating launching rails 54 and 60.

SELF-PROPELLED PROJECTILE (SECOND EMBODIMENT)

A second form of projectile formed in accordance with this invention is illustrated in FIG. 5. The projectile 70 is formed with a generally cylindrical body 72 which houses the propellant and nozzle (not shown) and has a nose portion 74 at the forward end thereof. A cylindrical sleeve 76 is mounted for rotation about the projectile body 72 such as through the use of journal or ball bearings (not shown) or other suitable friction reducing means. A plurality of fins 78 are fixedly attached to the sleeve 76 and are symmetrically spaced about the periphery thereof. Furthermore, in accordance with this invention, a plurality of guide studs are fixedly attached to the sleeve and symmetrically spaced about the sleeve. As shown in FIG. 5, there are two groups of guide studs 80, 82 spaced longitudinally apart, one group 80 being located adjacent to the fins 78 and the other group 82 being spaced therefrom. A third group of guide studs 84 are fixedly attached directly to the projectile body 72 for imparting rotation to the body 72.

The guide studs 80, 82 mounted on the sleeve 76 cooperate with longitudinal grooves in a launcher, such as the grooves 64, 66 in the launcher 52 (FIG. 3) to longitudinally guide the projectile 70 during its launch and to prevent rotation of the sleeve 76 and fins 78. The guide studs 84 attached to the projectile body 72 coact with the partially helical groove 58 to impart rotation to the projectile body 72 which then rotates slowly relative to the finned sleeve 76.

SUMMARY

In operation, when the projectile 10 illustrated in FIG. 1 (or projectile 70 illustrated in FIG. 5) is launched from the launcher 52, the interaction between the curved launching rail 54 having the groove 58 therein and the projectile body studs 28 (84 on projectile 70) imparts a slow rotational motion to the projectile body, just enough to counterbalance or average out any geometrical or mass imbalances in the projectile but not fast enough to produce gyroscopic stabilization. The guide studs 32, 34 (80, 82, on projectile 70) coacting with the longitudinal grooves 64, 66 in the launcher 52 provide the longitudinal guidance and prevent rotational motion of the finned section 16. The finned section 16 (76 on projectile 70) provides the fin stabilization which permits the rocket to maintain a tangential alignment with respect to its flight path throughout the entire flight of the projectile. This combined effect of slow rotation and fin stabilization provides improved flight accuracy and stability without sacrificing range.

Claims

What is claimed is:

1. A self-propelled, fin stabilized projectile comprising an elongated, generally cylindrical projectile body, a plurality of rigid first studs symmetrically spaced about the periphery of said body, the proximate end of said first studs being directly affixed to said body to prevent relative movement between said first studs and said body, said first studs having a first length in the radial direction of said body such that the distal end of said first studs is adjacent to said body, a fin unit including a plurality of fins symmetrically spaced about the periphery of said body and extending outwardly therefrom such that the distal end of said fins is remote from said body, said fin unit being mounted on said body for rotational movement relative to said body about the longitudinal axis of said body and having a plurality of rigid second studs symmetrically spaced about the periphery of said body, said second studs having a second length in the radial direction of said body such that the distal end of said second studs is adjacent to said body and a plurality of rigid third studs symmetrically spaced about the periphery of said body and mounted for rotational movement relative to said body about said longitudinal axis, said third studs having a third length in the radial direction of said body such that the distal end of said third studs is adjacent to said body, said fins having a fourth length in the radial direction of said body measured to the distal end of said fins, said fourth length being significantly greater than said first, second and third lengths.

2. A self-propelled, fin stabilized projectile as defined in claim 1 wherein said fin unit is mounted adjacent to one end of said projectile.

3. A self-propelled fin stabilized projectile comprising:

a. an elongated generally cylindrical projectile body,

b. a plurality of rigid first guide studs symmetrically spaced about the periphery of said body, the proximate end of said first studs being directly affixed to said body to prevent relative movement between said first guide studs and said body, said first guide studs being adapted to be received within grooves obliquely oriented with respect to the longitudinal axis of said body to effect rotational movement of said body about its longitudinal axis as said projectile is propelled relative to said grooves, said first guide studs having a first length in the radial direction of said body such that the distal end of said first guide studs is adjacent to said body,

c. a fin unit including a plurality of fins symmetrically spaced about the periphery of said body and extending outwardly therefrom such that the distal end of said fins is remote from said body, said fin unit being mounted on said body to enable rotational movement about said longitudinal axis of said body relative to said fin unit, said fin unit having a plurality of rigid second guide studs symmetrically spaced about the periphery of said body and being located on one side of the center of gravity of said projectile, said second guide studs having a second length in the radial direction of said body such that the distal end of said second guide studs is adjacent to said body, each of said second guide studs being adapted to be received within a recess parallel to said longitudinal axis to longitudinally guide said projectile and prevent rotational movement of said fin unit relative to said recess when said projectile is propelled relative to said recess, and

d. a plurality of rigid third guide studs symmetrically spaced about the periphery of said body and mounted for rotational movement relative to said body about said longitudinal axis, said second guide studs having a third length in the radial direction of said body such that the distal end of said third guide studs is adjacent to said body, said third guide studs being spaced longitudinally from said fin unit and located on the other side of said center of gravity, said third guide studs being adapted to be received within a recess parallel to said longitudinal axis to longitudinally guide said projectile when said projectile is propelled relative to said recess the length of said fins in the radial direction of said body measured to the distal end of said fins is significantly greater than said first, second and third lengths and the distance between said body and the distal end of each of said first second and third guide studs being substantially equal.

4. A self-propelled, fin stabilized projectile as defined in claim 3 wherein said fin unit is mounted adjacent to one end of said projectile.

5. A self-propelled, fin stabilized projectile as defined in claim 4 including an annular collar mounted on said body for rotation relative thereto, said third guide studs being rigidly attached to said collar.

6. A self-propelled, fin stabilized projectile as defined in claim 4 wherein said first guide studs are aligned within a first plane, said second guide studs are aligned within a second plane and said third guide studs are aligned within a third plane, said first, second and third planes being perpendicular to said longitudinal axis and spaced apart longitudinally.

7. In combination,

a self-propelled, fin stabilized projectile comprising an elongated generally cylindrical projectile body, a plurality of rigid first studs symmetrically spaced about the periphery of said body and affixed thereto to prevent relative movement between said first studs and said body, said first studs having a first length in the radial direction of said body such that the distal end of said first studs is adjacent to said body, and a fin unit including a plurality of fins symmetrically spaced about the periphery of said body and extending outwardly therefrom such that the distal end of said fins is remote from said body, said fin unit being mounted on said body for rotational movement relative to said body about the longitudinal axis of said body and having a plurality of rigid second studs symmetrically spaced about the periphery of said body, a plurality of rigid third studs symmetrically spaced about the periphery of said body and mounted for rotational movement relative to said body about said longitudinal axis, each of said second studs having a second length and said third studs having a third length in the radial direction of said body such that the distal end of each of said second and third studs are adjacent to said body, said fins having a fourth length in the radial direction of said body measured to the distal end of said fins, said fourth length being significantly greater than said first, second and third lengths,

said projectile being placed in a projectile launcher comprising a first rail having a longitudinal axis parallel to the longitudinal axis of said projectile body, said first rail including a first groove extending longitudinally along a length of said first rail and having at least a portion thereof obliquely oriented with respect to the projectile longitudinal axis, one of said first studs being received within said first groove and coacting therewith to effect rotation of said projectile body about its longitudinal axis when said projectile is propelled relative to said launcher, said one of said first studs remaining in said first groove while said projectile moves longitudinally relative to said launcher and at least two spaced apart second rails each having a rectilinear groove extending parallel to the projectile body longitudinal axis, one of each of said second and third studs being received within each of said rectilinear grooves and coacting therewith to prevent rotation of said fin unit relative to said launcher during propulsion of said projectile body relative to said launcher and to guide said projectile during longitudinal movement thereof relative to said launcher.

8. The combination projectile and launcher of claim 7 wherein said first groove is aligned at an angle of approximately 1.degree. to 3.degree. with respect to the longitudinal axis of the projectile body, according to projectile launching speed.

9. The combination projectile and launcher of claim 7 wherein launching speed of said projectile and the angle of orientation of said first groove relative to the projectile body longitudinal axis are jointly formed to rotate the projectile body during launching within the range of 90 to 270 r.p.m.

10. In combination,

a self-propelled, fin stabilized projectile comprising an elongated generally cylindrical projectile body, a plurality of rigid first studs symmetrically spaced about the periphery of said body and affixed thereto to prevent relative movement between said first studs and said body, said first studs having a first length in the radial direction of said body such that the distal end of said first studs is adjacent to said body, a plurality of fins symmetrically spaced about the periphery of said body and extending outwardly therefrom such that the distal end of said fins is remote from said body, said fin unit being mounted on said body for rotational movement relative to said body about the longitudinal axis of said body and having a plurality of rigid second studs symmetrically spaced about the periphery of said body, a plurality of rigid third studs symmetrically spaced about the periphery of said body and mounted for rotational movement relative to said body about said longitudinal axis, said second and third studs being located on opposite sides of the center of gravity of said projectile, each of said second studs having a second length and said third studs having a third length in the radial direction of said body such that the distal end of each of said second and third studs are adjacent to said body, said fins having a fourth length in the radial direction of said body measured to the distal end of said fins, said fourth length being significantly greater than said first, second and third lengths,

said projectile being mounted in a projectile launcher comprising at least two spaced apart rails each having a rectilinear groove extending parallel to the projectile body longitudinal axis, one of each of said second and third studs being received within each of said rectilinear grooves and coacting therewith to prevent rotation of said fin unit relative to said launcher and to provide rectilinear guiding of said projectile during the propulsion thereof relative to said launcher, and an elongated rail aligned parallel to said projectile body and having an elongated groove extending along a length of said elongated rail and having a portion thereof obliquely oriented with respect to the projectile longitudinal axis, one of said first studs being received within said obliquely oriented groove and coating therewith while said projectile moves longitudinally relative to said rail to effect rotation of said projectile body about its longitudinal axis, said obliquely oriented groove being located so that the projectile and said first studs may move longitudinally relative to said launcher prior to engagement of the obliquely oriented portion of said elongated groove by said first studs.

11. A combination projectile and launcher as defined in claim 10 wherein said obliquely oriented groove has a rectilinear portion parallel to said longitudinal axis.

12. A combination projectile and launcher as defined in claim 10 wherein said obliquely oriented groove is in the shape of a partial helix.

13. A combination projectile and launcher as defined in claim 7 wherein said first rail is partially cylindrical and has a curvilinear surface spanning a finite arc of less than 180.degree..

14. A combination projectile and launcher as defined in claim 10 wherein said first rail is partially cylindrical and has a curvilinear surface spanning a finite arc of less than 180.degree..