US3572249A - High efficiency rocket munition - Google Patents

Abstract

A HIGH EFFICIENCY ROCKET MUNITION WHICH UTILIZES THE MOTOR CASE AS THE WARHEAD FRAGMENTATION CASE. THE WARHEAD EXPLOSIVE IS INSTALLED INSIDE THE MOTOR CASE AND PROTECTED FROM THE MOTOR HEAT BY A THIN INSULATOR. THE LETHALITY OF THE ROCKET MINITON IS INCREASED BY THE USE OF UNBURNED PORTION OF THE ROCKET MOTOR AS AN EXPLOSIVE IN THE EVENT IMPACT BEFORE BURN-OUT AND THE STABILITY OF THE SPIN STABILIZED ROCKET IS INCREASED BY DISTRIBUTING THE WEIGHT SO THAT THE AXIAL MOMENT OF INERTIA IS INCREASED WHILE THE LATERAL MOMENT OF INERTIA IS DECREASED.

Description

March 23, 1971 D M DAV|S HIGH EFFICIENCY ROCKET MUNITIOEN Filed Sept. 11. 1968 United States Patent O U.S. Cl. 102-49.3 2 Claims ABSTRACT OF THE DISCLOSURE A high efficiency rocket munition which utilizes the motor `case as the warhead fragmentation case. The warhead explosive is installed inside the motor case and protected from the motor heat by a thin insulator. The lethality of the rocket munition is increased by the use of unburned portion of the rocket motor as an explosive in the event impact before bum-out and the stability of the spin stabilized rocket is increased by distributing the weight so that the axial moment of inertia is increased While the lateral moment of inertia is decreased.

BACKGROUND OF THE INVENTION This invention relates to a high efficiency rocket munition and, more particularly, the invention is concerned with providing a rocket munition which will deliver greater destructive power to a target at a higher velocity by combining the functions of a rocket motor case and a gramentation case into one unit.

In a conventional rocket munition, be it fin stabilized or spin stabilized, there are two primary components, the warehead and the rocket motor, It is the function of the motor to accelerate the warhead to the desired velocity toward the target. After the propellant is burned, the motor case no longer serves any useful purpose except for a possible slight improvement of the ballistic coeflicient. Since the primary purpose of the rocket and warhead is the destruction of the target, the velocity acquired by the rocket motor itself and the energy absorbed thereby is wasted and serves no useful purpose.

The fragmentation pack or case of a conventional fragmentation warhead normally comprises about two-thirds of the warhead weight, which must also be accelerated. lf the functions of the motor case and the warhead case are combined an increase in efliciency can be obtined. This increase can be utilized to either increase warhead weight, increase delivery velocity, or decrease total munition weight.

SUMMARY OF THE INVENTION In the present invention the functions of the motor case and warhead case are combined by designing the motor case of steel or some other well known fragmentation material and lining the case with sufficient explosive to provide effective case fragmentation. The case may be designed to utilize fragmentation control by any of several Well known techniques, if desired.

The explosive cavity is next lined with sutiicient insulating material to protect the explosive from ignition or excessive decomposition from the heat of the burning rocket motor.

Accordingly, it is an object of the invention to provide a rocket munition wherein the unburned portion of the rocket motor is utilized as an explosive in event of impact before burn-out.

Another object of the invention is to provide a spin stabilized rocket of increased stability by distributing the warhead in such a manner as to increase the axial moment of inertia, decrease the lateral moment of inertia, and reduce the overturning moment.

A further object of the invention is to provide a rocket ice munition having increased warhead eiciency by increasing the contact area between the explosive and the fragmentation case. This is accomplished by utilizing the motor body as the fragmentation case.

These and other objects, features and advantages will become more apparent from the following description taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. l is a view in longitudinal cross section of a high efficiency rocket munition in accordance with the invention; and

FIG. 2 is a cross section taken along the line II-II of FIG. 1 showing the relative arrangement of the longitudinal elements.

PREFERRED EMBODIMENT OF THE INVENTION Referring now to the drawings in which like reference characters are used to refer to like parts in the views, the high eiciency rocket munition according to the invention includes a missile designated generally by the reference numeral 13. A fuse adaptor 15 containing a detonator 17 for propagating the explosive reaction is disposed at the forward end of the missile 13. A fuse 19 which initiates the warhead explosive train is threadably attached to the fuse adaptor 15 and forms the nose of the missile. A fragmentation/ motor case 21 is attached at the rearward end of the fuse adaptor 15 and extends back therefrom. The case 21 serves to contain the motor pressure as well as being frangible to produce fragments when the missile 13 reaches the target and explodes,

A charge of explosive 23 is placed inside the frangible case 21 adjacent to the inner wall surface thereof and covers substantially all of said wall. The explosive charge 23 extends inwardly therefrom and lls about one-fifth of the cavity of the case 21. A light insulator 25 is positioned inside the case 21 adjacent to the inner surface of the explosive charge 23. The insulator 25 acts to protect the explosive charge from the heat generated by the rocket motor.

Inside the insulator 25 and concentric thereto is the motor grain 27 which serves to propel the rocket to its destination. A nozzle 219 which may be of the multiport type is located at the aft end of the rocket munition \13 and seals the base of the rocket as well as forming part of the propulsion system. The motor grain 27 is preferably of the solid type and is provided with an inner cavity 31 to provide a combustion surface so that the effective energy in the charge can be utilized in the most efficient manner.

MODE OF OPERATION In operation, the rocket munition 13 is propelled by its own self-contained rocket motor. The total rocket is enveloped by the fragmentation/motor case 21 of the rocket, thus eliminating the need for a separate motor assembly which would normally be necessary to propel the rocket munition.

The nozzle 29 also forms an integral part of the rocket munition resulting in a simple and compact unit which is economical to manufacture in the large quantities required for tactical usefulness.

The fuse 19 located at the nose of the rocket serves, with the detonator 17, to energize the explosive charge 2.3. Any conventional type of fuse and detonator may be used for this purpose including a proximity fuse arranged to detonate the rocket as it approaches the target or a time fuse which operates after the passage of a predetermined time interval. Also, under certain conditions, it may be desirable to simultaneously detonate the explosive charge 23 at various positions along its length in order to assure that a completely effective explosion of the rocket munition results.

Several additional advantages accrue to the high efficiency rocket munition described herein. For example, the eciency of the energy coupling between explosive and metal is a function of the area of contact and, in the present invention, the contact area is maximized. Also, since the warhead is not located at the front of the rocket, an increase in lethality is obtained through the reduced tendency for the warhead to bury in the ground before detonation. The fact that the explosive detonation wave moves backward along the charge gives a rearward velocity to the fragments thereby reducing their tendency to strike the ground inefectively.

Although this munition concept is applicable to both spin and aerodynamically stabilized weapons further advantages accrue when the rocket is spun by any one of several well known techniques such as canted nozzles, nozzle vanes, pre-spin motors, ried launch tubes and others. Since this design does not have a heavy warhead in front of the motor, the center of mass can be located further aft than in conventional rockets thereby reducing the overturning moment arm and increasing stability. Also, with this concept the shift of center of gravity during motor burning which occurs in conventional rockets is substantially reduced or eliminated. High gyroscopic stability is provided by the herein disclosed design because the ratio of axial moment of inertia to transverse moment of inertia is high due to the new and unusual distribution of the warhead mass.

It is inherent in this design that as the motor burns the ratio of axial to transverse moments of inertia will increase. The spin required to stabilize a given body increases with velocity. Increasing the moment of inertia ratios reduces the added spin required. The stability advantages of this munition become apparent when either canted nozzles or nozzle vanes are used to provide spin because the reduced spin requirement improves propulsion eiciency. This becomes more evident when pre-spin motors or nozzles are used and when rifled launch tubes are used. The boost velocity to produce the required spin is decreased thereby reducing the size and mass of the launcher. Also, in aircraft launchers, the recoil momentum transferred to the aircraft is reduced permitting higher firing rates and larger caliber weapons.

Although the invention has been described in the foregoing specication in terms of preferred embodiments thereof, it should be understood that variations and modiiications can be made in the construction and relative shape and size of the elements Without departing .from the true spirit and scope of the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. A high efficiency rocket munition comprising a cylindrical fragmentation/motor case having a cavity therein, a fuse adaptor attached to the forward end of said fuse adaptor, a hollow cylindrical explosive charge concentrically disposed adjacent to the inner Wall of said fragmentation/motor case and `filling at least one-fifth of the cavity therein, a detonator positioned between said fuse and said explosive charge, an insulator of cylindrical configuration disposed adjacent to the inner surface of said hollow explosive charge, a motor grain within said insulator for propelling said rocket, and a nozzle located at the aft end of said rocket munition for controlling the flow of gases therefrom, said fragmentation/motor case serving to contain the motor pressure during propulsion and to produce fragments upon explosion of the rocket munition after reaching the target.

2. The rocket munition dened in claim 1 wherein the stability thereof is increased by distributing the Weight such that the axial moment of inertia is increased and the lateral moment of inertia is decreased.

References Cited UNITED STATES PATENTS 3,257,804 6/1966 Thomas et al. 102-49.5UX 3,326,129 6/1967 Gould 102-493 3,331,324 7/1967 OSS et al. l02-49.5 3,357,356 12/1967 Bischoff IGZ-49.5

SJERLIN R. PENDEGRASS, Primary Examiner U.S. Cl. X.R. IGZ-49.5, 67

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