Patent Publication Number: US-7584922-B2

Title: Spin-stabilized correctible-trajectory artillery shell

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority, under 35 U.S.C. §119, of German patent application DE 10 2006 057 229.7, filed Dec. 5, 2006, which is herewith incorporated by reference in its entirety. 
   BACKGROUND OF THE INVENTION 
   Field of the Invention 
   The invention pertains to an artillery shell that is spin-stabilized and allows for trajectory correction. The artillery shell has a canard guidance unit that is rotationally decoupled from its munition body and an electrical generator in the engagement region of the guidance unit into the munition body for operation of a canard adjusting system. 
   A configuration of that kind is known from commonly assigned U.S. Pat. No. 7,267,298 B2 and German patent application DE 1 01 34 785 A1. That artillery shell, referred to as artillery munition, which is unguided in itself is distinguished in that a spatial (that is to say three-dimensional) trajectory correction can be implemented with a sole single-axis pair of guidance canards, that is to say with a control system which in itself is only two-dimensional, and thereby the delivery errors which are system-inherent in themselves can be crucially narrowed down in target-oriented relationship in all directions. The canard vanes which are adjustable by electric motor means with respect to the longitudinal axis of the munition, on the guidance unit, the narrowed front part of the artillery shell, which is roll-decoupled from the munition body, cause a pitching or yawing movement of the artillery shell depending on the respective instantaneous position thereof, as detected by sensor means, in space. Preferably those two canard vanes, for pitch adjustment thereof with respect to the longitudinal axis of the munition, have a common canard shaft which extends transversely with respect to the longitudinal axis of the munition through the guidance unit and which is rotatable by means of a single adjusting motor. 
   The electrical power for operation of that adjusting motor is obtained by way of the relative speed between the munition body and the guidance unit in a generator which supplies the adjusting motor directly and/or by way of an energy storage device. Generator operation represents a mechanical resistance against the roll motion by virtue of the mass moment of inertia of the shell body. Termination of the operation of the adjusting motor, in comparison with the load situation, represents a relief of the load on the generator and correspondingly influences the reaction movement which is effective between the stator and the rotor of the generator and which in turn has reactions on the instantaneous roll characteristic of the artillery shell and thus its flight stability. Therefore the energy which is not required by the adjusting motor at the time is switched over to a substitute load in order as far as possible to avoid such reactions on the roll characteristic by virtue of a constant loading in respect of the generator. 
   As the above-mentioned energy storage device can only be small, because of the extremely constricted installation conditions, in practice it is only possible to envisage switching over the adjusting motor to a resistor, as the substitute load. The Joulean heat which is generated therein makes a substantial additional contribution to the thermal radiation of the other functional components such as the generator and the adjusting motor by virtue of induction heating and bearing heating. As a result, the thermal balance sheet in the interior of the guidance unit, which is hermetically sealed in relation to the outside world, can rapidly become functionally critical. 
   BRIEF SUMMARY OF THE INVENTION 
   It is accordingly an object of the invention to provide a spin-stabilized, trajectory-correctible artillery ammunition, which overcomes the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides for an artillery shell of the general kind wherein the load-induced thermal radiation does not lead to a critical rise in temperature in the guidance unit. 
   With the foregoing and other objects in view there is provided, in accordance with the invention, a spin-stabilized correctible-trajectory artillery shell, comprising: 
   a munition body; 
   a canard guidance unit rotationally decoupled from the munition body and connected to the munition body in an engagement region, the canard guidance unit including canard surfaces; 
   a canard adjusting system connected to and adjusting the canard guidance unit; 
   an electrical generator disposed in the engagement region for powering the canard adjusting system; and 
   a substitute load at or in the canard surfaces, wherein the generator is connected to and can be switched over to the substitute load at or in the canard surfaces. 
   In a preferred embodiment of the invention, the canard guidance unit is formed with rigidly mounted anti-spin canards. 
   In other words, the objects of the invention are achieved in that the rise in temperature caused by the substitute load occurs outside the guidance unit, namely in canard surfaces. As a result there is no need for structural measures in the interior of the guidance unit in order to channel those amounts of heat governed by the substitute load and to dissipate them into regions which as far as possible are not critical in terms of function. For, the substitute load no longer contributes to the thermal balance sheet in the interior of the guidance unit because it is only produced outside it, at or in the surfaces of the canard vanes. The rise in temperature which occurs there is in itself already not critical in terms of function and in addition is rapidly dissipated by the afflux flow of air over a large area. 
   Because the thermal radiation from the substitute load is no longer critical, that also affords extensive options in terms of controlling the relative movement between the munition body and the guidance unit by way of substitute loads which are staggered in respect of the way in which they can be switched over. That is of particular interest if operation of the generator influences the roll rate of the guidance unit by way of a variable energy delivery or is used by way of a constant energy delivery for roll stabilisation purposes. Conversely the generator can also be temporarily operated as a motor from the energy storage means for roll angle adjustment. 
   In order therefore in accordance with the invention to avoid an additional heat source in the interior of the guidance unit, the substitute load to which the generator can be switched over in the roll-decoupling engagement region of the canard guidance unit of a roll-stabilized correctible-trajectory artillery shell for the avoidance of load fluctuations at the end of operation of the adjusting motor, is in the form of an electrical resistor on, at or in canard surfaces behind the afflux flow edges thereof, and this preferably being in relation to anti-spin canards which are not adjustably mounted. 
   Additional developments and alternatives to the solution according to the invention are set forth in the further claims and, also having regard to the advantages thereof, the description hereinafter of a preferred embodiment of the invention which is diagrammatically shown in simplified form not entirely true to scale, being restricted to what is essential. 
   Other features which are considered as characteristic for the invention are set forth in the appended claims. 
   Although the invention is illustrated and described herein as embodied in spin-stabilized correctible-trajectory artillery shell, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
   The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     The single FIGURE of the drawing is a partly broken-away view in axial longitudinal section of the configuration of the guidance unit in front of the munition body. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the FIGURE of the drawing in detail, the artillery munition  11 , also referred to as an artillery shell or projectile, which is to be launched in spin-stabilized mode is provided with a guidance unit  13  in front of a munition body  12  which accommodates the payload, instead of being provided with a conventional impact, time or proximity fuse. Behind its radome  14 , the guidance unit  13  is equipped with sensor devices  15  for trajectory monitoring and target approach, but in particular also with an adjusting system  16  for trajectory control. For that purpose, an adjusting motor  17  acts on a corresponding lever. In this embodiment, the lever is a single adjusting shaft  18  of a single-axis canard adjusting system  16  which extends transversely with respect to the longitudinal axis  19  of the artillery shell  11  through the guidance unit  13 . The latter is a configuration in the form of a hollow cone. The adjusting shaft  18  has its two ends non-rotatably connected to a respective canard adjusting vane. The vanes project radially from the outside contour of the guidance unit  13 —but not in over-caliber fashion—in mutually diametrally opposite relationship. 
   By way of bearing locations  20  which are axially displaced relative to each other and which are preferably in the form of rolling bearings, the guidance unit  13  is roll-decoupled from the munition body  12  into which it engages rearwardly with a tubular connecting portion. Depending on the instantaneous roll position of that engagement region of the guidance unit  13 , that is to say also of its adjusting shaft  18  which is disposed in front thereof in the conical region, in relation to the munition body  12 , pitch adjustment of the canard adjusting vanes with respect to the longitudinal axis  19  of the munition by rotation of the adjusting shaft  18  thereof leads to a change in trajectory as a consequence of pitching and/or yawing movement of the artillery shell  11 . In order dynamically to manage that adjusting procedure, a pair of anti-spin canards  21  is fixed to the guidance unit  13  transversely with respect to the pair of canard adjusting vanes. The canards are at a structurally fixedly predetermined pitch angle with respect to the longitudinal axis of the munition in order to reduce the spin of the guidance unit  13  as soon as possible after the artillery shell is fired from the rifled bore to a value of the order of magnitude of less than ten percent of the stabilisation spin of the munition body  12 . 
   That difference in rotary speed is used in an electrodynamic generator  22  for producing electrical energy in particular for operation of the adjusting motor  17  but also for example for the sensor devices  15 . For that purpose the munition body  12  is provided between the bearing locations  20  along a circle which is concentric with respect to the axis  19  with mutually spaced, alternately poled permanent magnets  23 . As a consequence of the relative rotary movement between the munition body  12  and the guidance unit  13 , the induction coils  24  thereof pass through a magnetic alternating field and thus, without the requirement for slip rings, supply a high-frequency ac voltage to a voltage preparation circuit  25  with rectification in the interior of the tubular connecting portion of the guidance unit  13 , which connecting portion carries the generator  22 . An energy storage means  26  of small structural size can be re-charged or buffered therefrom, for example for safeguarding an interruption-free power supply for example for the sensor devices  15  or for temporarily switching over to the motor mode of the generator  22 ; in particular however the adjusting system  16  with its canard adjusting motor  17  is connected to the voltage preparation circuit  25 . 
   The relief of load on the generator  22  which occurs with the termination of the adjusting procedure as a consequence of the adjusting motor  17  being switched off, and the jump in torque that this entails between the guidance unit  13  and the munition body  12  is practically suppressed by a change-over switching logic means  27  diverting the energy demand of the adjusting motor  17  into a substitute load  28  of suitable dimension. The load  28  is provided in or at (that is to say in relation to) the anti-spin canards  21  which are mechanically fixed to the guidance unit  13 , for example as diagrammatically shown in the form of elongated conductors closely behind the afflux flow edge  29  of the anti-spin canards  21  or in the form of substantially flat conductors on or in the canard surface  30 . In the latter case the respective canard vane of the anti-spin canards  21  can also substantially or entirely comprise electrically conducting material (for example suitably adjusted plastic material), in which case for example an insulating barrier  31  which is indicated in the drawing compels a current flow path which is sufficiently long for an adequately high level of resistance in respect of that substitute load  28 . 
   The crucial consideration is that the joulean heat occurring in the substitute load  28  does not additionally constitute a burden on the thermal balance sheet in the interior of the guidance unit  13  and also does not have to be specifically dissipated from the interior of the guidance unit  13 —but is equally generated outside the guidance unit  13  and disposed of in a highly effective fashion by way of the canard surfaces  30 . The canard surfaces, of course, have a very strong afflux flow thereagainst.