FR2585771A1 - METHOD FOR MANUFACTURING AN EXTENSIBLE ROTOR DRIVER OUTPUT CONE AND THIS TUBE - Google Patents

Abstract

THE INVENTION RELATES TO AN EXTENSIBLE TUBE OUTLET CONE FOR A ROCKET ENGINE. THE EXTENSIBLE CONE 10 CONSISTS OF A THIN SHEET OR SHEET MEMBRANE WHICH IS FOLDED SO THAT THE REAR AREA OR LARGE DIAMETER OF THE MEMBRANE CAN BE FOLDED SO THAT THE CONE IS FOLDED TO AN OVERALL LENGTH AND A NOTABLE MAXIMUM DIAMETER REDUCED AND WITH A VERY INCREASED RIGIDITY IN RELATION TO ITS TOTALLY DEPLOYED STATE. IN THE FOLDED STATE, THE MATERIAL CONSTITUTING THE REAR PART OF THE MEMBRANE FORM SEVERAL LAYERS ARRANGED IN THE FRONT PART IN A MANNER SUCH THAT THE DEPLOYMENT IS CAUSED BY THE GAS FLOW FROM FRONT TO THE REAR OF THE ENGINE-ROCKET 12 A THE INTERIOR OF THE CONE 10. FIELD OF APPLICATION: ENGINES-ROCKETS.

Description

The invention relates to an improvement made to an exit cone of

  extensible nozzle for rocket engines designed to operate in a vacuum

  or in conditions close to vacuum.

  Ballistic missile systems for deep space or satellite probes require high performance primary propulsion systems,

  low weight and highly habitable. With the exception of

  see propellant fluids, the largest element of the propulsion system is the engine exhaust nozzle rocket. The rocket engine nozzle occupies a large part of the available space compared to

its mass.

  The exit cone of a conventional rocket engine nozzle is designed for performance

  optimum at the average altitude of the intended path.

  One of the functions of the exit cone is to provide an inclined surface against which the exhaust vent plume of the rocket engine can be carried to provide a portion of the forward thrust of the engine.

  rocket engine. The exhaust plume increases with

  Rocket engine study due to lower pressures

  from the ambient atmosphere to the highest altitudes.

  At low altitude, the exhaust plume is too

  small for the available surface of the exit cone.

  As a result, a partial vacuum tends to form on the inner edges of the exit cone, thereby generating atmospheric drag on the rocket. At high altitude, the exhaust plume is too large for the exit cone, so much of the energy

  potential is not used. An engine nozzle-

  rocket large enough to fully utilize the exhaust from a rocket engine at low pressures existing at high altitude would normally occupy an extraordinarily large proportion of available storage space in tanks, submarines and between the floors of a missile to

multiple floors.

  Various proposals have been made in the prior art to provide a high expansion nozzle, which can be folded into a reduced length configuration and housed in a minimum space, and can be deployed in a configuration suitable for high speed operation. altitude after engine ignition and takeoff. These proposals consisted in using: (a) a cone or an extension skirt of the engine-rocket nozzle, which is

  folded in a single layer towards the

  and forward of the engine-rocket nozzle in a position of

fallback, and which is actuated, that is

  Deployed, towards a position of ex-

  complete tension by the flow of front to back of the engine gases

  as described in US patents

United States of America N 3 358 933 and -

N 4,272,956;

  (b) an inflatable cone or skirt of prolon-

  rocket engine which is folded forward of, and folded around,

  of the rocket engine nozzle, external

  At this nozzle, then inflated by the rocket engine gases to take a desired frustoconical shape behind the engine nozzle,

  as described in the United States Patent

  United States of America N 3,596,465; (c) a cone or extension skirt of the rocket engine which is folded forward of, i.e., folded around the rocket engine nozzle, externally

  this nozzle, and comprising a set

  with a bonnet attached to the rear end or skirt outlet, which hermetically closes the cone of extension and which, when the engine is started, seals the gas pressure inside the cone sufficiently for the skirt to unfold towards its deployed configuration, as

described in the United States patents

United States of America N 3 711 027 and

No. 3,784,109;

  (d) rocket engine extender cone

  which is folded towards the front of, that is-

  ie folded around the engine nozzle, outside thereof, and comprising a plurality of mechanical actuators for unrolling the skirt towards its deployed configuration, such as

described in the United States patents

United States of America No. 3,346,186,

No. 4,125,224, No. 4,162,040,

  No. 4,184,238, No. 4,387,564, No. 4,213,366,

  N4,383,407 and N4,489,889; (e) a rocket motor extension cone as described in (d), further comprising a skirt attached to the rear end of this cone, which tapers towards the inside of the extension cone when the latter is in its folded position and which is brought into its deployed configuration by a flow from the front to the rear of the rocket engine gases, as described in U.S. Patent Nos. 4,125,244, N 4,162 040, N 4 184 238 and

No. 4,387,564.

  Previous proposals pose problems in achieving high performance over the entire planned path, as they do not achieve the high rates of expansion required for the flight of a high-altitude rocket, staying within the bounds of length,

of weight and cost.

  Thus, with regard to the prior art mentioned in (a) above, which prior art is diagrammatically shown in FIG. 1 of the accompanying drawings described below, it is obvious that, since the length Ls, measured on the along the right meridian of the extended part 1 of a rigid cone

  2, can not exceed the radius Rf of the opening of

  of the cone 2, the length La measured along the longitudinal axis 3 of the extension 1 of the cone shall be

  less than Ls. This significantly limits the rate of expan-

  can be obtained in point (a) of the prior art, because the length L must be short enough to be s

  contained inside the cone 2 in its folded state.

  The point (b) of the prior art consists in using an inflatable extension cone consisting of two woven stainless steel panels connected to one another and comprising a connecting pipe intended to discharge the rocket engine gases between the panels for the inflation of the cone. Double panels and connection tubing undesirably increase the weight, bulk and

complexity of construction.

  With regard to the point (c) of the prior art, the need for the hood assembly attached to the outlet end of the extension skirt

  undesirably increases the weight of the cone

  the transverse load imposed on this cone and the

complexity of construction.

  Points (d) and (e) of the prior art involve the use of mechanical actuators such as pneumatic cylinders which undesirably increase weight, bulk and complexity.

construction.

  The present invention relates in particular to

  tying an expandable output cone shape for motor-

  rocket in which the extension of the nozzle is folded inwardly of itself and is characterized

  by means allowing the right meridian, corresponding to

  to the length L of the representation of the prior art of FIG. 1, to be much greater than Rf or even greater than Re which is the radius of the exit plane of the extension 1 of the cone. This allows a quantity of the cone extension membrane material, sufficient to produce a very high surface area ratio.

  the exit plan, to be withdrawn with a sense of

  significantly increased under a very small envelope

  compared to the prior art, while allowing the use of

  Thinner and therefore lighter membranes

  for the extension of the exit cone.

  It is an object of the invention to provide an improved method for the manufacture of an extensible rocket engine output cone having a very large surface ratio from a sheet or flat membrane of refractory metal or other material. which extensible exit cone can be collapsed by folding to be retracted and whose deployment is itself amenable to induction by a flow of gas from the front to the rear in this cone under the effect

engine operation.

25857 71

  Another object of the invention is to

  a method of folding a sheet (of metal, etc.) forming a notched curved membrane, in the form of a cone or truncated cone, with a right meridian, in such a way that the rear zone or large diameter of the cone, which is made by edge-to-edge attachment of the opposite ends, can be folded to be folded to a very short overall length, a minimum diameter and with substantially increased rigidity compared to the fully deployed unit, and more particularly wherein, in the folded state, the material constituting the rear portion of the membrane forms multiple layers within the front portion so that deployment can be caused.

  by a flow of gas from the front to the back,

laughter of the cone.

  Another object of the invention is to

  an improved process as described above for the manufacture of an extensible nozzle exit cone, characterized in that, when

  fold the cone for folding, the membrane of the cone extensively

  nozzle outlet bend is folded inwardly of the cone, by multiple folds, from the rear end.

  Another object of the invention is to

  an improved process for the manufacture of an expandable nozzle outlet cone from very thin membranes, characterized in that in the folded form the extensible outlet cone of the nozzle

is very rigid.

  Another object of the invention is to

  an improved expandable exhaust cone of the jet engine nozzle in which the expandable cone is folded inwardly of itself, in multiple folds, from the rear end, to allow a quantity of membrane material of the extension the nozzle, sufficient to establish a very large surface area to the exit plane, to be folded under a very small envelope, the extensible exit cone in the folded form being very rigid.

  To achieve these objects and reach from

  In one embodiment, an embodiment of the invention comprises a folding system of a foil (made of metal, etc.) developed as a curved and notched membrane, in the form of a cone or a truncated cone, with right meridian, in such a way that the rear zone or larger diameter of the cone, which is: made by joining the two opposite straight edges, can be folded down to be folded under a very short overall length, a maximum diameter and with rigidity significantly

  increased compared to the fully deployed set.

  In the folded state, the material constituting the rear portion of the cone forms multiple layers within a

  front part of the cone so that deployment is easy-

  caused by a gas flow from the front to the rear

  the rocket motor towards the inside of the cone. It is not necessary that the front part of the membrane be folded over a large area, and for the same purposes,

  it may be advantageous not to bend it at all.

  The invention will be described in more detail

  with reference to the accompanying drawings as examples

restrictions and on which:

  FIG. 1 is a partial diagram illustrating

  certain relationships, as mentioned above.

  demement, a nozzle extension of the prior art; FIG. 2 is a perspective view, partly in section, of a rocket engine comprising an extensible nozzle exit cone according to the invention, the extensible cone being shown in its folded state;

  FIGS. 3 to 6 are views in

  pective showing the expandable nozzle outlet cone of Figure 2 at various stages of its deployment; - Figure 7 is a view of the rear end of the extensible nozzle in its folded state; FIG. 8 is a partial plan view, in particular of a fifth, of the developed outer surface of the expandable nozzle outlet cone of FIGS. 2 to 7; Fig. 9 is a partial perspective view showing how a thin sheet of metal can be positioned on the table of a brake press so that fold or crease lines are formed therein; Fig. 10 is a fragmentary perspective view showing, alternatively, how a thin metal foil can be placed on a die and wrinkled to the press so that fold or crease lines are formed therein; Fig. 11 is a partial cross-section illustrating the operation of the stamping press of Fig. 10; FIG. 12 illustrates a piece of curved, thin, cut sheet metal worked with the brake press, obtained in a preliminary stage to that consisting in forming the extensible nozzle outlet cone of the invention; FIG. 13 is a perspective view illustrating a way of folding the symmetric membrane

  axis along the various fold lines, starting with

  at the rear end of the deployed cone to fold the rear end of the cone for its folding in a front portion thereof; FIG. 14 is a diagram illustrating a certain relationship of the extensible nozzle exit cone according to the invention for purposes of comparison with corresponding relationships existing in the prior art as illustrated in FIG. 1; and FIG. 15 is a partial longitudinal section illustrating a flanged support system for

  the extensible nozzle of the invention.

  In accordance with the invention, there is provided an improved method for making an expandable nozzle outlet cone for attachment to the output end of a rocket motor nozzle. Part of the rear end of the cone is initially folded inwardly of a front portion of this cone for

  fold the cone into a low volumi-

  nous. The rear end folded inwards is

  designed to be unfolded, upon ignition of the engine-

  rocket, under the effect of the flow of the front to the rear of the engine gasesfusée through the extensible cone of outlet of the nozzle. This extension or deployment of the nozzle exit cone increases the useful planar exit surface ratio of the expandable nozzle.

  the rocket motor at the surface of the throat of the nozzle.

  By folding only a part, for example both

  third, from the rear end to the inside of the

  before the extensible exit cone in its folded state, a larger planar surface of

  when the rocket motor is switched on to provoke

  increase the pressure inside the cone to ensure a fast and smooth unfolding

  and therefore a deployment of the cone towards its position of exten-

if we.

  The method of the invention comprises several steps of cutting a piece of heat-resistant ductile material, as hereinafter described, in a curved, plan view, dimensionally appropriate as illustrated in FIG. 12, with opposite straight ends capable of be brought into an edge-to-edge arrangement to form a truncated cone. The curved shape of the part is chosen so that the end of the smaller radius of the truncated cone is suitable for attachment to the output end of the jet engine nozzle and the end of the larger radius

  of such a size as to obtain the increase

  of the section report.

  After the step of cutting the curved piece of heat-resistant thin material, this piece is deformed on a portion adjacent to the longer curved side to form a pattern comprising two sets of folds or folds in each of five substantially equal sectors dividing

  the play, a first game of which is directed towards ob-

  servant from the outside of the room (when

  that it is then formed into a truncated cone), and a second set of folds being directed in the direction away from the observer. The two sets of pleats are formed on the surface of the workpiece and in a mutual arrangement such that when the opposite straight ends of the curved workpiece are attached to each other to form a truncated cone, the rear end of the cone is able to bend inwards in a portion of the front end in several layers-folded inwards. Although the part is described as being divided into five sectors, it is obvious that a number of sectors much larger than five, all sectors being of the same size, can be provided if desired. A minimum of four sectors

  However, it is necessary for the folding and unfolding

age of the membrane are possible.

  Other stages of cone manufacturing

  extensible output of the nozzle of the invention

  attempt to fix the opposite straight ends of the curved piece in an edge-to-edge arrangement, for example by a single weld to form a truncated cone, this operation being followed by an axially symmetrical folding towards the interior and forward, for example by hand, of a part of the surface located in front of the large diameter or the rear end of the cone, following several folds towards the inside of

  way to collapse the cone for a compact fold.

  Figures 2 to 6 illustrate a particular embodiment of an expandable nozzle outlet cone 10 according to the invention for a

  rocket engine indicated by reference numeral 12.

  The cone 10 can be made, as described above, by folding a sheet or flat membrane of refractory metal or other heat-resistant material

  and properly cut erosion.

  As a non-limiting example, it should be noted that the nozzle 14 of the rocket motor 12 may have a groove 13 with a diameter of 9.78 cm. The diaphragm designated 16 of the expandable or expanded extension nozzle cone 10 may form a half-angle of 17 and is conventionally and conveniently secured (not shown) to the cone 14 of the engine fuse into a thicker material. with a diameter of 58.4 and 68.6 cm. The cone 14 thicker, section report

  weaker, may have a half-angle greater than 170.

  On the expandable exit cone 10 to mem-

  The ratios of the sections are 256 to the exit plane 18 and 80.3 to a vanishing point designated at 20, from the generally conical shape. At this intermediate point 20, the view from the rear end

  of the folded configuration has a pentagonal shape

  nal. One fifth of the developed surface of the cone, having lines of folds or folds and fold directions, is shown in Fig. 8. Fig. 2 illustrates the expandable exit cone 10 in the fully folded state. The overall reduction in length along the longitudinal axis 22 of the extensible cone 10 is about 115% of the radius of the exit plane and more than 200% of the radius deployed at the intermediate point 20. This value is equal to more than twice the that obtained in the prior art, as shown in FIG. 1. The free length of the conical diaphragm 16, between the point where it moves away from the attachment to the nozzle 14 of the rocket engine and the point 20 of leakage from the form globally

conical, is about 40.6 cm.

  As is obvious to those skilled in the art, larger or smaller reductions in the envelope of the deployed state in the collapsed state and shapes having higher exit plane section ratios can be achieved. or smaller by varying the angular frequency, the number of approximately circumferential folds and the distances between adjacent folds. In the fully folded state as shown in Figures 2 and 7, the folds at the rear end of the expandable cone 10 form a pyramid 24 whose apex is located on

  the longitudinal axis 22, which pyramid 24 closes the

  cone exit end 10. This closing of the cone is sufficiently tight that, at the beginning of operation or ignition of the rocket engine 12, the resulting pressure rise inside the cone and the flow of gas from the front to the back cause an opening of the folds of the cone 10 to its fully deployed state, following a gentle sequence

  opening folds and successive layers.

  Figure 3 illustrates the situation at

  deployment. The elements or folds approximated

  Radial bearings, shown at 26, which retain the gas at the beginning of the flow from front to back, are clearly visible. Each side of these radial elements 26 is composed of a zone located between the exit plane and the second approximately circumferential fold indicated at 34, in the middle of the fifth width of the complete development zone shown in FIG. Each radial element 26 comprises two layers

formed by the membrane 16.

  Figures 4 and 5 show the approximately radial elements 30 and 32, respectively,

  who continue to be exposed during the deployment.

  These radial elements 30 and 32 retain the gas which

  forcibly prolongs the unfolding and unfolding

  is lying. In FIG. 6, all that remains to be done for a complete deployment is the establishment of a sufficient flow of gas flow from the front to the rear inside the membrane 16 of the exit cone 10. force the latter into the

stable circular shape.

  In most of the extensor cone

  10 described in FIGS. 2 to 6, three layers of material of the membrane 16 are in contact in the folded state. The triangular areas 36 between the exit plane 18 and the first approximately circumferential fold, indicated at 28 and adjacent to the fifth boundary of the complete development zone, as shown in FIG. 8, form a small region in which five layers of material of the membrane 16 are in contact in the folded state. In the partial plan development of the outer surface of the expandable exit cone 10, as shown in Fig. 8, fold lines

  are represented in solid lines or in punctuated lines.

  Tilles. The lines shown in full lines have their top pointed towards the observer and those shown in dotted lines have their vertex directed in one direction

away from the observer.

  According to the invention, the drawing of the folds or folds, as shown in FIG. 8, can be carried out in an appropriately cut-up membrane 16, of curved shape, constituting a piece

  44, by means of a brake press, as schematically illustrated

  Figure 9. A brake press is a

  device well known in the art, and is widely

  used to fold and produce shapes from sheets and plates of ferrous and non-ferrous metals. The particular advantages of a brake press are its flexibility, the ease and speed with which it can be passed from one fold to another, and the low tooling cost. A news

  is a low-speed punch press com-

  as a bench or a narrow table, relatively long, and a slide mounted between extreme frames. The slides can be operated mechanically or hydraulically. To facilitate the operation of the brake press, it may be desirable to use a conventional modified brake press in a manner well known to those skilled in the art. Thus, it is necessary to adjust the length of the edge on the table 40 of the brake press 38, as shown in Figure 9, to accommodate the different lengths of the different plies. It is therefore intended to modify the brake press 38 using several tables 40 each having an edge of the required length and which can be substituted for each other for the formation of folds or gathers in the

membrane 16.

  As is also obvious to those skilled in the art, the designs of the pleats or folds may be

  formed in the membrane 16 by means of a tin press

  page 42, as shown in Figures 10 and 11, the membrane 16 being placed on a flat stamp and the folds being formed by pressing. The stamping press 42 may be chosen, as desired, so that the requested pleats are formed on both sides

  of the membrane sheet or piece 44, as shown in FIG.

  FIG. 12, during a stamping operation, or only a fifth of this piece, as shown in FIG.

  shown in Figure 8, in each of five opera-

successive stamping operations.

  FIG. 12 illustrates a piece or sheet of membrane to be cut out 44, worked with the brake press or stamped, and it shows the various folds or

  gathers having been formed in the membrane 16.

  After the operations carried out with the brake press or the stamp, the opposite straight ends 46 and 48 are fixed to each other in any suitable manner, for example by a single weld, so

  to form the extensible cone 10 of output.

  With reference to FIGS. 8 and 12, it can be seen that the drawings of the folds or folds formed on the piece 44 of FIG. 12, from which the cone 10 is made, comprise first, second and third

  folds or fold lines approximately circumferentially

  and spaced 28, 34 and 54, respectively. The first

  fold line 28 and third fold line 54 extend across the width of the sector indicated at 60 in FIG. 8, constituting one-fifth of the complete curved piece 44 shown in FIG. 12. The second fold line 34 sector 60 is

  consisting of two fold lines 62 and 64 which meet

  angle at a midpoint 66 of the sector 60 and extending in directions

  opposed to respective median points of sec-

  adjacent to the sectors 60. Although the lines or folds 28, 54 and 34 (formed by the folds 62 and 64) are straight, they form approximately circumferential fold lines over the entire

  width of the room, as shown in Figure 12.

  As shown, the three fold lines 28, 34 and 54 are approximately equidistant from each other, the first fold or fold line 28 being substantially the same distance from the join.

  fold lines 62 and 64 that the outer edge incur-

ve and along sector 60.

  The fold or fold lines 28, 54, 62 and 64 constitute several lines of a first group of lines formed in the piece 44 with respect to which the top of the fold is oriented towards the observation.

  tor. Other fold lines forming part of this first group of lines comprise a line 68 which connects the junction 66 of the fold lines 62 and 64 to the midpoint 70 of the folding line 28 and lines 72 and 74 which connect the joint 66 at a corresponding end of the fold line 54. Others of the fold lines of the first group of lines connect the midpoint 76 of the longest curved line.

  sector 60 at the ends and at intermediate points

  spacers 78, 80, 82 and 84. Other fold lines 86 and 88 connect a corresponding end of the fold line 28 to the most curved line of the fold line 28.

sector 60.

  The crease lines of a second group of

  lines have a vertex oriented in an elongated direction

  of the observer. They comprise a fold line 90 which connects the midpoint 76 of the curved line of the sector 60 to the midpoint 70 of the first fold line 28. Other of these fold lines include lines 92, 94, 96 and 98 which connect the midpoint 66 of the second fold line 34 to the ends and intermediate points of the first fold line 28. Fold lines and 102 connect one end of the fold line 28 to the longer curved edge of sector 60 and fold lines 104 and 106 connect the other end

  of the fold line 28 at this edge.

  FIG. 13 shows how the piece formed of the diaphragm of FIG. 12, when it is in the form of the exit cone 10, can be folded

  inwardly on itself gradually and sym-

  at least one axis, from the rear end to the vanishing point 20 on the forward end,

  to bring the extensible cone 10 into its folded state.

  This folding can be done by hand.

  Folds to initiate folding in the interior

  10 of the expanded cone 10 along the approximately circumferential fold line 28 have been indicated by the letters A to E in FIGS. 12 and 13. One out of two of the folds, for example the folds A, C, E, B and D are pinched, in turn, from the surface

  16. In particular, the clamp

  The effect of the fold A is to fold the membrane 16 outward along the fold line 88. This facilitates the inward folding along the fold lines 104 and 106. The pinching of each of the other folds C, E , B and D, in turn, allows the membrane 16 to be folded similarly in the sectors containing these folds. The pinched pleats can then be folded inward, one after the other, along the approximately circumferential fold line 28. The order of this folding can be the same

  than the one in which the folds were pinched, that is,

  that is, the order A, C, E, B and D. A first inward layer thus being produced, the appearance of the cone is substantially the same as that shown in FIG. 5. A substantially identical process can be followed to perform the folding inwards

  from the rear end of the cone to a second layer.

  Thus, as can be seen more clearly in FIG. 12, the folds used to perform this operation are designated by the letters F to J. Among these folds, only the fold I is visible in FIG. 13. The nip of the fold I causes a folding of the membrane 16 outwardly following the fold 68, as shown in FIG. 12. This facilitates the folding of the membrane 16 inwardly along the fold lines 96, 98 and 92, 94. Here and as before, the folding of one fold out of two is carried out in the order F, H, J, G and I, for example. At the end of this folding, the folds F to J can then be folded inwards, one after the other, along the line approximately

  circumferential folding 34. This folding towards the interior

  folds can be performed in the same order in which they were pinched. The appearance

  cone 10 having the second layer folded towards the

  is the same as the one shown on

Figure 4.

  The folds used to effect folding of the trailing end of the cone 10 along the approximately circumferential fold line 54 have

  have been designated by the letters K to 0 in FIG.

  As before, every other fold, for example in the order K, M, O, L and N, is folded, one fold after the other, outwards, at the fold lines 72 and 74, and inward along the fold line 108. Among these folds, only the folds K and 0

  are shown in Figure 13. At an intermediate step

  In this folding operation, the appearance of the cone is substantially the same as that shown in FIG. 2. At the end of this folding, the extensible ring is in a folded state for folding, as

  illustrated in Figure 1, its rear end appears

as shown in Figure 7.

  For convenience, the previous mode of folding inward of the extensible exit cone

  is here called "axis symmetry" folding.

  Figure 14 is a diagram illustrating

  Some relations concerning the extensible nozzle cone 10 of this embodiment of the invention.

  described with reference to Figures 2 to 13, which relate to

  tions are significantly different from the relationships

  as described previously, relating to the embodiment of the prior art shown in FIG. 1. With reference to FIG. 14, it can be seen that, since the length Ls of the meridian is folded into several layers, this length L may be much greater than the radius Rf of the outlet opening of the part of the cone 10, designated at 50, which is not folded. This portion, as shown in FIG. 8, is that between the front cut 52 of the membrane 16 and the third approximately circumferential fold line 54. It should be noted

  that, if desired, the Ls value may be higher than

  greater than Re which is the radius of the extensible cone 10 at the outlet plane 18. As previously described for the embodiment of the prior art shown in FIG. 1, the length Ls of the prior art

can not exceed Rf.

  In Figure 15, there is shown, in partial section, a portion of the folded cone extension 10, equipped with a flanged support system 112 for attachment to a rocket engine 12 '. In particular, a front portion 114 of the expandable core 10 is retained between the outer rear surface 116 of the cone of an embedded nozzle 14 'of the rocket motor 12' and a conical annular band 120 of plastic insulation. A ring 122 of titanium closure, surrounding the band

  annular 120 of insulation, has an interior surface

  re 124 which fits tightly on the outer surface

  of the strip 120 of plastics material. The ring of

  Titanium 122 is attached to a lip 123 protruding rearward of the rocket engine fairing 133 by means of several bolts 125 suitably spaced apart.

* in the circumferential direction.

  In order to support the cone extension 10 in a suitable position with respect to the cone of the rocket motor nozzle 14 ', a ring of five-sided plastic material is provided. The ring 126 of plastics material may advantageously be formed of four separate sections to facilitate assembly of the support system 112 by clamping. On its rear face, as shown in Figure 15, the ring 126

  of plastic material is in abutment against the annul-

  Isolation wire 120 made of plastic material and the closure ring 122. On its front face, the ring 126 made of five-sided plastic material abuts with a

  annular shoulder 128 located on the cone 118 of the motor-

  rocket. A ring 130 of titanium having a circumferential groove 132 is slid on the surfaces

  circumferential circumferences of the closure ring 120

  re in titanium and ring 126 made of plastic.

  An O-ring 134, which may be made of rubber or any other suitable elastomeric material, is housed in the groove 132 to seal the interface between the fairing 133 of the rocket engine and the assembly 112. A band The annular ring 136 of plastic material may be secured by a suitable adhesive to the contiguous surfaces of the rocket motor cone 118, the plastic ring 126 and the titanium ring 130. The membrane 16 used in the manufacture of the expandable nozzle cone 10 can be made of any suitable ductile metal or alloy that is resistant to heat and erosion. The advantageous metal alloys for this embodiment are: Niobium and 10% hafnium Niobium, 10% tungsten, 10% hafnium and 0.1% yttrium (melting point of about 2400 C) Tantalum and 10% of tungsten ( melting point of about 3040 ° C. Each of these metal alloys can be used in sheet form. At a thickness of 0.127 mm, the weight of the first niobium-based sheet is equivalent to about 0.838 mm of carbon-carbon 2D and the tantalum-based sheet weight is equivalent to about 1.473 mm of carbon-carbon 2D "term

2D meaning two-dimensional).

  In summary, it should be noted that the embodiment of the invention as described herein allows a sufficient amount of membrane material to establish a very large sectional ratio to the exit plane, to be folded into a reduced envelope into comparison with the prior art. Thus, as shown in FIG. 1 which represents the prior art, since the length Ls, measured along the meridian of the extensible cone, can not exceed the radius Rf in the zone of attachment of the extensible cone to the nozzle of the rocket motor, the length L measured along a

  the longitudinal axis of the expandable cone shall be

greater than the length Ls.

  According to the invention as represented

  14, it can be seen that, since the length Ls is folded into several layers, this length L can be much greater than the radius Rf of the zone of attachment of the extensible cone to the nozzle of the engine. rocket, or even superior to

  Re radius of the exit plane of the extensible cone.

  In the embodiment of the invention as illustrated, due to the reduced length of the front portion of the cone and the fact that the folded rear portion maintains the shape at the interface, the folded shape of the cone 10 is very small. rigid. In the absence of this rigidity, the diaphragm exit cone could not be used at all, because it would be

  too inconsistent before the ignition of the engine.

  Since the required stiffness of the unbent membrane of the exit cone is determined

  by the load of inertia before use (that is,

  that is, before the establishment of the internal pressure which stiffens the structure during use), the invention makes it possible to use thinner exit cone membranes and therefore lighter than would otherwise be possible. Thus, the maximum output diameter that can be achieved in practice

  (before weight gain requires an increase in

  higher impulse than the ratio

section allows) is increased.

  It goes without saying that many modifications can be made to the process and the nozzle described

  and shown without departing from the scope of the invention.

Claims (15)

  A method of manufacturing an expandable nozzle exit cone for attachment to the output end of a rocket motor nozzle such that at least a portion of said exit cone is initially folded into the interior of the engine. cone for a compact fold relative to the nozzle of the rocket engine and can be unfolded when the rocket engine is switched on under the effect   flow from front to rear of the engine gases-   rocket through the cone to substantially increase the ratio of the useful section of the exit plane of   the engine-rocket / exhaust cone nozzle assembly   The method of the invention is characterized in that it consists of: (a) cutting a workpiece into a thin sheet of ductile, heat-resistant material so that it has a plan view, a curved shape having opposite ends which can be brought edge to edge to form a truncated cone whose end of   small radius can be fixed at the   output of an engine nozzle-   rocket whose end of large radius   is of such a size as to   blurt the desired increase in the ratio of sections; (b) deforming at least a portion of the curved piece, in close proximity to the large curved side, from one end of the curved piece to the other to form in this piece several folds constituting first and second groups, the top of the folds of the first group being turned towards the observer and the top of the folds of the second group   being turned in a different direction   of the observer, all the folds of the second group extending transversely to the workpiece between folds of the first group so that when the opposite ends of the workpiece are attached to each other edge on board the surface of the cone, over at least a part of its length, can be folded inwards and forwards in several layers folded internally; (c) fixing the opposite ends of the curved piece together to form a truncated cone; and   (d) to gradually bend towards the   and forward of the end of large radius of the truncated cone, the surface of said cone in several layers folded inwards, so that the truncated cone is realized in a manner   allowing it to be fixed by its   mite of small radius at the end   output of the nozzle of a motor-   rocket while the cone is in the folded position relative to this nozzle, and that, when the rocket engine is on, the folded cone frustum can be deployed under the effect of the flow of   the front to the rear of the engine gases-   rocket through said truncated cone to provide a substantially increased ratio of the useful section of the output plane of the engine-rocket / exhaust cone assembly extensible to the useful section of the engine throat. the engine nozzle rocket.   2. The process according to claim 1, wherein   characterized in that the part is formed of an alloy comprising niobium and 10% hafnium.   3. The process according to claim 1, wherein   characterized in that the part is formed of an alloy comprising   niobium, 10% tungsten, 10% hafnium and 0.1% yttrium.   4. The process according to claim 1, wherein   characterized in that the part is formed of an alloy comprising   tantalum and 10% tungsten.   5. The method of claim 1, wherein   characterized in that, in the step of deforming the curved piece, the folds are formed in a pattern which is repeated in each of at least four   substantially equal sectors dividing the room.   6. Process according to claim 5,   characterized in that the pattern formed in each sector comprises folds of the first group forming first,   second and third fold lines which are approximately   substantially concentric with the curved sides of the workpiece, the first of said fold lines being closest to the longer curved side of the workpiece, the third of the fold lines being closer to the shorter curved side of the workpiece, and the second   folding lines being approximately equidistant   the first and third fold lines, the width of the first and third fold lines being equal to that of the sector, the second fold line comprising two folds which meet at a small angle, substantially at an intermediate point of the width of the sector and which extend into adjacent sectors, others of said folds of the first group connecting the junction folds of the second fold line to a midpoint of the sector of the   first line of folding and at the ends of the third   bending line, still others folds of the first group connecting a central point of the longest curved line of the sector at the ends of the first fold line and at points thereof located between the center and the ends of said first fold line, other folds of the first group connecting the ends of the first fold line to the longer curved line, said folds of the second group connecting said central point of the longest curved line of the sector at a central point of the first fold line and connecting said longest curved line, from a point adjacent to each side of the sector, to the ends of the first fold line, and also connecting the Fold Junction of the second fold line at the ends   of the first line of folding and at points of that   ci located between its center and its extremities.   7. The method of claim 6, wherein   terized in that the drawing is repeated in each of   five equal sectors dividing the room.   8. The method of claim 7, wherein   characterized in that the folded layers of the truncated cone oppose the gaseous flow from the front to the rear of the rocket motor to cause an increase in pressure inside the cone when the engine is ignited -fusee, this pressure rise being sufficient to apply a high force intended   unfold and unfold the cone towards its extended position. if we.   9. Extensible nozzle for rocket engine   (12), intended to be fixed to a nozzle (14) of motor-   rocket having a groove (13), to increase the ratio of the useful section of the nozzle assembly.of the rocket motor / extender nozzle exit cone to   a useful section of a throat of an engine nozzle   rocket, characterized in that it comprises a curved membrane (16) of ductile material, resistant to heat, said membrane having opposite curved sides, one of which is longer than the other and having ends (46). , 48) which are adapted to be brought edge to edge to form a truncated cone, the portion of the membrane forming the rear end of the truncated cone being deformed by a plurality of lines of complementary folds forming first and second groups, the top of the crease lines (28,   54, 62, 64) of the first group being turned towards   from the outside of the membrane, and the top of the fold lines (90, 92, 94, 96, 100, 102, 104, 106) of the second group being rotated in a direction away from the observer, the lines   folds of the first group extending both   loosely and longitudinally to the curved membrane   and the fold lines of the second group extending only   transversely to this membrane so that the truncated cone can be folded inwards, in axial symmetry with respect to the cone, in multiple layers from the rear end so that the cone can be folded into a compact form relative to the rocket motor, and also so that the expandable nozzle can be unfolded to its deployed position by a flow from the front to the rear of the engine-rocket gases through the cone- to the after ignition of the rocket engine.   10. A nozzle according to claim 9,   characterized in that the membrane is formed of an alloy   comprising niobium and 10% hafnium.   11. A nozzle according to claim 9, which is   characterized in that the membrane is formed of an alloy comprising niobium, 10% tungsten, 10% hafnium and 0.1% yttrium.   12. A nozzle according to claim 9, which is   characterized in that the membrane is formed of an alloy   comprising tantalum and 10% tungsten.   13. A nozzle according to claim 9, which is   characterized in that the deformation of the membrane by said lines of cooperating folds of the first and second groups is effected according to a drawing which is   repeated in each of at least four   equals (60) dividing the curved membrane.   14. A nozzle according to claim 13, characterized   characterized in that said drawing is repeated in each   of the five sectors dividing the curved membrane.   15. A nozzle according to claim 14, characterized   characterized in that folds of the first group form   folding lines (28, 34, 54) which are approximate-   concentrically at the curved sides of the membrane, the first (28) of said fold lines being closest to the longer curved side of said membrane, the third (54) of said fold lines being closest to the most curved side of said membrane; short of the membrane and the second (34) of said fold lines being approximately equidistant from the first and third fold lines, the width   areas between the exit plan and the first   bending line, the first and second fold lines and the second and third fold lines being approximately the same, the second of said folding lines comprising two folds (62, 64) which meet forming a small angle therebetween, substantially at an intermediate point (66) of the width   sector and extending into adjacent sectors.   cents, others of said plies (68, 72, 74) of the first group connecting the junction (66) of the folds of the second fold line to a midpoint (70) of the sector of the first fold line (28) and the ends of the third fold line (54), still others (78, 80, 82, 84) of the first group folds connecting a central point (76) of the longest curved line of the sector at the ends of the first fold line (28) and at points thereof between the center and ends of said first fold line, others (86, 88) folds of the first group connecting the ends of the first fold line at the longest curved line of the sector, said folds (90, 100, 102, 104, 106) of the second group connecting said central point of the longest curved line of the sector to a central point (70) located on said first fold line and connecting said longest curved line, from a point adjacent to each side of the sector, at the ends of the first fold line and connecting the junction of the folds of the second fold line to the ends of the first fold line and the points of this   last located between its center and its extremities.