Abstract:
This missile launcher is characterized in that the cells do not extend in rows parallel to an elongated chimney, but by surrounding a central chimney, providing a more compact and especially lighter arrangement with identical resistance conditions.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS OR PRIORITY CLAIM 
     This application is a national phase of International Application No. PCT/FR2005/050569 entitled “Missile Launcher”, which was filed on Jul. 11, 2005, which was not published in English, and which claims priority of the French Patent Application No. 04 51516 filed Jul. 13, 2004. 
     TECHNICAL FIELD 
     The subject of this invention is a missile launcher. 
     Such a machine comprises a structure delimiting cells for housing individual missiles, also called ammunition in the art, at least one chimney for gas flow and a plenum chamber, the cells and the chimney opening at an end face of the launcher (generally the upper face) and the plenum chamber extending to an opposite end of the launcher; the cells and the chimney open into the plenum chamber through apertures of a base plate forming the ceiling of the chamber. Further, swinging doors close the cells and the chimney when the launcher is at rest and are pulled aside when the missiles must be fired. The combustion gases produced in the cells are ejected into the plenum chamber and discharged from the launcher through the chimney. Their large pressure exerts consequent forces on the plenum chamber, the chimney and the whole structure of the launcher. The designer should generously dimension the launcher and face constraints on the acceptable weight limit, at least when the launcher is to be integrated into a marine vessel. 
     BACKGROUND 
     In a known design, two parallel rows of four cells each are positioned on either side of a chimney with a rectangular section extending over the whole length of the rows. The large length of the size of the chimney imposes a thick chimney duct in order to withstand the significant flexure produced by the pressure of the gases, and therefore the significant weight. 
     A design derived from the previous one is shown in EP 0 473 498 A. The single chimney is divided into four chimneys with circular section, each of which faces a cell of each of both rows. In other words, each small chimney resulting from the division is placed between two cells. The chimneys are of a circular shape and therefore better withstand the internal pressure of the gases. However, as this solution remains a heavy solution, it is proposed that chimneys be built in composite material in order to reduce their weight, but it is doubtful that a significant gain in weight may be achieved since these chimneys can no longer be thermally assembled to the remainder of the structure and should therefore themselves withstand the forces to which they are subject. 
     SUMMARY 
     The invention relates to a missile launcher which enhances the oldest design in a different way from what is discussed in the aforementioned patent. 
     Unlike the prior designs where the cells were positioned in rows along the chimney, here they extend around it, in the form of a circle or regular polygon. A not insignificant reduction of the size of the launcher may be obtained with this arrangement of the cells, and especially a significant gain in mass correlated with a greater strength of the structure, notably when it is integrated into a marine vessel such as a surface ship, for reasons which will be given in the following of this description. 
     An excellent realization consists of arranging eight cells in a square at the angles and at the middles of the sides, and the chimney occupying the centre thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described in connection with the figures. 
         FIG. 1  is an overview of the structure of the launcher, 
         FIGS. 2 and 3  are two comparative views of an arrangement with two launchers, 
         FIG. 4  is a vertical sectional view of the launcher, 
         FIG. 5  is a horizontal sectional view of the launcher, 
         FIG. 6  is an isolated view of the chimney, 
         FIG. 7  is a partial view of the top of the launcher, 
       and  FIG. 8  is a view of the base plate surmounting the plenum chamber. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a launcher of the prior art, including certain details also again found in the invention. This is the oldest design. A structure  1  of plates and intersecting plates is used as a framework for the launcher and delimits eight cells  2  distributed in 2 parallel rows of four and a chimney  3  intermediate to the rows. The cells  2  and the chimney  3  are delimited by square tubular ducts which do not appear on the figure, for the cells  2  and rectangular ones for the chimney  3 . The cells  2  and the chimney  3  open on the outside at one end of the launcher located on the top, through an upper plate  4  which may correspond to a deck of a surface marine vessel. Doors  5  and  6  close the cells  2  and the chimney  3  at rest and clear them by opening around hinges  7  and  8 . The launcher further comprises a lower plenum chamber  9 , the ceiling of which is formed by a base plate  10  to which the remainder of the structure  1  is connected and which is provided with apertures at the location of the cells  2  and of the chimney  3  to provide passage for the combustion gases from those cells into the latter.  FIG. 2  shows a possible arrangement of both of these launchers on a same support giving the possibility of firing up to sixteen missiles: the launchers are placed side by side with the chimneys  3  in alignment by their main extension direction, a small gap separating them. 
     A comparative diagram of the invention is illustrated in  FIG. 3 . The same number of sixteen cells is used for the same number of two launchers  11 . Here, the launchers  11  have a square shape and the cells  12  are placed at its periphery, three on each side, or also four at the angles of the square, and four between two neighboring angles. A single chimney  13  placed in the centre of the square is again found between the four cells  12  at the middle of the sides. Unlike the prior design, the chimney  13  is not elongated but circular. 
     A comparison with the arrangement of  FIG. 2  shows that for an identical cell section, the launcher  11  is more compact that the launcher derived from the prior design by means of the smallest section of the chimney  13 . This benefit of space is not completely utilized with a construction with several launchers  11  since they are spaced out more apart from each other than in the prior designs. Actually it is required that the doors of the cells  12  located towards the outside, open by swinging around hinges  14  on the periphery, and therefore towards the other launcher  11  for cells  12  located in opposition. The doors of the chimneys  13  consist of two semi-circular halves joined by a line and opening by moving away from each other again by a swinging movement. 
     Sufficient separation of the launchers  11  should therefore be maintained in order to avoid impacts between the doors. This drawback of saving less space as one might have expected is however compensated by structural reinforcement of the vessel and therefore by a significantly larger gain in weight. 
     When the launchers according to the invention or to another design are placed in a vessel, a well  15  should be provided for receiving them. The structure of the vessel is considerably weakened by it. By using the invention, it is however possible to limit this drawback by positioning reinforcement girders  16  between two launchers  11  as this is also seen in  FIG. 4 . The large sides of the well  15 , which are therefore subject to more significant deformations, are then stiffened and may be built in a much more lightweight manner. The space of the well  15  which is not occupied by the launchers  11  and which comprises a space at their periphery and between them, is a passageway  17  for maintenance personnel to access the cells  12 . 
       FIG. 4  and the following figures illustrate the structure of a launcher  11 . A layer of I-beams  18  supports the plenum chamber  19  of the launcher  11 , which is in the shape of a flat box with a square section and which is strongly stiffened depending on the pressures which it should withstand. Its lateral sides are formed with two plates provided with intermediate stiffeners. Its ceiling is formed by a base plate  20  also consisting of two superimposed plates and connected by stiffeners, other I-girders here. Apertures  21  are placed through the base plate  20  under each cell  12  and under the chimney  13 . The structure of the remainder of the launcher is substantially in a form of a cage and it comprises sixteen uprights  22  regularly positioned in four rows to the corners of the cells  12 . They support guide rails  23 , also vertical, for square missile ducts  24  which delimit cells  12 , and they are joined by horizontal and intersecting crossbars  25  around the launcher  11  within it. 
     The chimney  13  is also visible in  FIG. 5 . It is formed by a circular duct  26 , the diameter of which is slightly larger than the dimension of the ducts of the missiles  24 . Contrary to what was the case with the rectangular chimney, the chimney duct  26  may extend very close to the ducts of missiles  24  as it remains at a distance from the closest uprights  22  thanks to its circular shape. Evacuation of the gases is facilitated by the largest diameter which may be ascribed to it. The presence of a convergent inside the ceiling of the plenum chamber  19  is still possible and it reduces the pressure losses and the pressure of the gases exerted in the chimney  13  and the lower plenum chamber  19 . The convergent  34  appears in  FIG. 8  and consists of a widening of the chimney  13  downwards into the base plate  20 , over at least one portion of its height. 
     It appears in  FIG. 6  that the chimney duct  26  may be assembled to uprights  22  passing close to it by welded small plates  27 , and at the base plate  20  of the plenum chamber  19  by triangular-shaped ribs  28 , two of the sides of which are welded to the duct  26  and to the base plate  20  and which pass between the apertures  21  of the cells  12 . To summarize, by using a relatively narrow chimney  13  but with a resistant circular shape, it is possible to use a metal duct  26 , the weight of which is not excessive and which may be firmly assembled to the remainder of the launcher&#39;s structure by small plates  27  and ribs  28 , which improves the strength of the whole. 
     Another aspect of the invention is to be discovered in  FIG. 7 . The structure of the launcher  11  is closed at the top by an upper plate  29  which is connected to the deck of the vessel as seen in  FIG. 4  via seal gaskets. The doors  31  of the cells  12  should protect them from the environment and especially from big waves. In the traditional design, the edge of the doors is directly supported on the upper plate  29  of the launcher via a gasket, which is of doubtful value. Rather it is recommended to establish a borderline called a pavement  32  on the upper plate  29  around each of the cells  12  and to have the doors  31  rest on them; the doors  31  are provided with a gasket  33  with a closed notably circular section, which is crushed on the pavement  32  and provides a much better seal.