US3245620A - Missile steering control - Google Patents

Description

April 12, 1966 J. c. MCEWEN 3,245,620

MISSILE STEERING CONTROL Filed Dec. l5, 1961 INVENTOR.

I BY (M5/522 @5226211621 A e/Ww United States Patent 3,245,620 MISSLE STEERING CONTRL John C. McEwen, Indianapolis, ind., assigner to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Dec. 13, 1961, Ser. No. 159,091) 2 Claims. (Cl. Z39-6525) This invention relates to a guidance control for a missile or the like and more particularly to a steering mechanism for a missile having a number of fixed or nonorienting exhaust nozzles.

An object of the invention is to provide a steering control for a missile that is simple in construction and eco- `nomical to manufacture, and one that changes the attitude of the missile by control of the missile fluid exhaust stream.

A further object of the invention is to provide a missile having a guidance control combined with a unique exhaust nozzle construction designed to prevent erosion of the nozzle surfaces.

A still further object of the invention is to provide a missle construction consisting of a number of fixed fluid jet exhaust nozzles symmetrically disposed around the axis of the missile including an apparatus selectively movable to block` the passage of the exhaust fluid through some of the nozzles to thereby create a jet turning force on the missile upon the passage of fluid through the unblocked nozzles. v

lt is a further object of the invention to provide missile attitude control by an apparatus controlling the missile -jet exhaust stream while maintaining `the losses in thrust occasioned by this control at a minimum.

Other objects, features and advantages will become apparent upon reference to the succeeding detailed description of the invention and to the drawings illustrating the preferred embodiments thereof, wherein,

FIGURE l is a cross sectional View of a portion of the exhaust end of :a missile taken on a plane indicated by and viewed in the direction of the arrows 1-1 of FIG- URE 2,

FIGURE 2 is a cross sectional View on a reduced scale taken on a plane indicated by and viewed in the direction of the arrows 2 2 of FIGURE 1, FIGURE 3 is a View of a portion of FIGURE 1 illustrating a modification thereof, and

FIGURE 4 is a cross sectional View corresponding to FIGURE 2 illustrating the modification of FIGURE 3.

The invention provides a guidance system for a rocket or the like having a number of fixed or nonorienting gas jet exhaust nozzles. It consists in general of a control apparatus rotatably mounted on the outlet end of the rocket to partially or completely block off one or more of the inlets to the nozzles so that an unbalance or difierential in thrust is created between the gases flowing out of the different nozzles to effect a jet turning force on a rocket.

More specifically, FIGURE 1, which is essentially to scale, shows the aft or outlet end of an -annular rocket casing closed by an annular plate 12. Plate 12 may be secured to the casing in any suitable manner (not shown). The plate has three (FIG. 2) spaced clusters of gas jet metering holes 14 to permit the escape of gas through the plate. Each of the clusters is spaced 120 apart around the plate and an equal radial distance from the rocket longitudinal axis 15. The holes 14 in each of the clusters are equally spaced from each other and an equal distance radially from a centerline 16. Each of the centerlines 16 coincides with the longitudinal axis of a fixed convergent-divergent jet exhaust nozzle 18. The nozzles are secured to the downstream side of plate 12 by any suitable means such as flanges 19, and project .predetermined flight path is provided as follows.

axially downstream therefrom. The nozzles are symmetrically disposed around the closure plate in the same relationship to each other as the clusters of holes.

Each of the nozzles 18 is of the same size and has its inlet 2f) covering a cluster of holes 14 with which it is aligned. Each has a converging inlet wall 24, a venturi or throat 26, and a bell shaped diverging outlet wall 27. A conical inner body or plug 2S is fixed to plate 12 on the centerline of the nozzle and projects axially into the iniet 20. The nozzle converging wall 24 together with the plug 28 and holes 14 in effect form three tubular-like guide passages 3l) each angularly disposed with respect to the nozzle centerline. The passages 30 may be considered as separated at the holes 14 while having a common outlet 34 at their opposite ends at the vertex 36 of the throat of the nozzle.

The throat of each nozzle is so sized that its area is, for example, equal to approximately fifty percent of the total area of the inlet holes 14. Thus, the gases have sufcient velocity imparted to them as they pass into and through the passages 30 so that they flow in substantially a straight path towards the vertex of the throat without diffusing into each other, i.e., into the area around the plug 28. The proportioning of the plug and nozzle walls therefore provides a kinetic convergent flow of the gases at the vertex point 36 in the throat as shown by the arrows 38 in FIGURE l, thereby preventing the gases from scraping and eroding the throat surface.

.As will be described in more detail later, the blocking of any one or all of the holes 14 of a cluster by an apparatus to be described controls the volume of gas passing into the particular nozzle associated with the cluster. The thrust imparted by the flow of gas through this nozzle is therefore either reduced or terminated as compared to the fiow through the unblocked nozzles. This unbalance in thrust effects steering of the rocket.

The chamber 49 defined by the aft end of casing 1@ and the closure plate 12 may be the aft end of a combustion chamber from which the combustion product gases will flow out through the nozzles 18; or, the chamber may be, for example, the outlet duct for the gases emanating from a combustion chamber or turbine section located upstream of the closure plate. ln either case, under normal operation, the same volume of exhaust gases will flow out through each of the holes 14 and nozzles 18 to impart an axial thrust to the rocket. The thrust forces around the outlet are therefore balanced.

Attitude control of the rocket for maintaining it on a As stated previously, the inlets to some of the nozzles are adapted to be either partially or completely blocked to create an unbalance in thrust between the flow of gases out of the different nozzles, thereby providing a jet turning force on the rocket. To accomplish this, a relatively fiat hollow circular plate 42 is mounted to slide over the face 44 of the closure plate 12 to either partially or completely block one or more of the holes 14 of any one cluster of holes.

FIGURES l and 2 show the plate 42 formed integral with a hollow supporting arm 46 secured to a hollow shaft 48 rotatably mounted on the axis 15 of the closure plate. The shaft and arm are secured to the rotatable portion 56 of a journal bearing S2, the mating stationary portion 54 being formed as a boss or hub projecting from the closure plate. Bearing portion 50 has two radially spaced annular flanges 56 rotatably fitted into mating grooves 58 formed in the portion 54.

Arm 46 and the blockage plate are supported for rotation around plate 12 by an anti-friction load bearing 60 having its inner race secured to the arm and its outer race resting against the closure plate face. The bearing supports the arm 46 and plate 42 against the force of the .35 exhaust gases acting on them from within the chamber 4t) and provides the necessary axial clearance to permit the arm and plate to translate freely in a circular path around the face of closure plate l2.

The integral portion 61 connecting the arm 46 and the blockage plate 42 is shown bent or offset so that the plate 42 lies substantially flat against the face of the closure plate. While not shown, it is within the scope of the invention to provide the portions of blockage plate 42 and arm 46 that face the closure plate 12 with grooves or pockets that lare open to the gas pressure in chamber 40 to balance the loadings on the integral arm and plate, thereby reducing the forces required to rotate them.

The hollow interior of plate 42 and arm 46 are adapted to be filled with, in this case, a solid coolant 62, such as a synthetic polymeric amide of which nylon is an example, to insulate the plate and `arm from the hot exhaust gases in chamber 46. Nylon is a convenient coolant because it vaporizes at a temperature below the nozzle operating temperature. The hollow shaft 43, which opens into the arm 45, acts as a vent for the release of the gases produced upon vaporizing of the coolant by the heat of the exhaust gases on the plate and arm. Other suitable coolants, both liquids and solids, could be used as a matter of choice without departing from the scope of the invention.

The arm and blockage plate are variably rotated by a worm gear drive mechanism including gear 63 splined to shaft 4S and meshing with the worm shaft 64 of an electric motor 66. The control mechanism for the automatic intermittent operation of motor 66 is not shown since it is known and is unnecessary for an understanding of this invention. Suice it to say, however, that the motor is activated in response to a predetermined signal from the control system indicating a necessity for attitude control of the rocket or missile, and is deactivated in the same manner when the rocket attitude is in accordance with a predetermined schedule.

While the driving mechanism has been illustrated as an electric motor, it will be clear that other similar operating mechanisms, such as hydraulically operated devices, for example, could be used without departing from the scope of the invention.

For normal operation of the engine, the blockage plate 42 will be positioned between clusters of holes as shown in dot-dash lines 70 in FIGURE 2 so as not to interfere with the normal exhaust of the gases out through the nozzles. The exhaust gases therefore pass out through all of the holes 14 in each of the three clusters to impart a pure axial thrust to the rocket, the thrust forces being balanced around the closure plate.

Attitude control of the rocket is accomplished, as stated previously, by providing a thrust differential between the gases flowing out of the different nozzles to provide a jet turning force on the aircraft. Therefore, the degree of rotation of the arm 4e and plate 42 will vary as a function of the turning forces necessary. For example, if only a small turning force is necessary, the plate will'be rotated to close say only one hole 14 to provide a small thrust differential between nozzles; whereas, if a large turning force is needed, the plate will be rotated to cornpletely block off all the holes of any one cluster.

Therefore, as seen in FIGURE 2, when the control system (not shown) indicates that attitude control is necessary, motor 66 is activated to rotate shaft 48, arm 45, and the blocking plate 42 in nite increments to either partially (dot-dash lines 80, FIG. 2) or completely block one hole I4 of a cluster. Upon continued rotation, the plate will partially or completely (full lines, FIG. 2) block all of the three holes 14 of any one cluster at any one time. The progressive and cumulative blocking of the holes will therefore progressively decrease the flow of exhaust gases out through the nozzle associated with the cluster of holes, thereby decreasing the thrust through this particular nozzle as compared to the thrust resulting 4 from the passage of gases through the remaining unblocked nozzles.

In the case where only one or more but not allof the holes of a cluster are covered by the plate 42, the gases in chamber 4) will then pass into the unblocked or only partially blocked tube-like passages 30, will have a kinetic convergence at the vertex of the throat of the nozzle, and will be expanded uniformly o-ut the bellshaped exit portion of the nozzle. By a kinetic convergence is meant that the convergence of the angular forces of the gases passing through the holes 14 and passages Si) are utilized so that the masses converge together at the vertex of the nozzle throat and are compressed through the nozzle. The gases, of course, will pass out through all of the passages 30 in the other nozzles Without interference. rfhus, a jet turning force is created by the greater increments of thrust resulting from the tlow of the gases through the other nozzles, these greater thrust forces acting to turn the rocket about its pivotal axis (not shown). The choice of the nozzle to be partially or completely blocked of course will depend upon which direction the rocket is to be turned. The rocket is therefore capable of being turned in a 360 orbital path.

It should be noted that if a solid propellant is used as a fuel to produce the exhaust gases in chamber 4%, blocking off all of the holes in a cluster will result in 'a pressure rise in chamber 4t? which will increase the burn rate of the propellant and the generation of gases. Thus, more effective vectoring forces will be obtained. If less vectoring is desired, only one of the holes 14 would be blocked off thereby resulting a minimum chamber pressure rise and the least additional generation of gases.

The FIGURES 1 and 2 construction illustrate a gas blocking plate capable of blocking all of the holes of any one cluster at one time. A modication shownin FIGURES 3 and 4 illustrates the use of a blockage member 42' capable of blocking only one hole of any one cluster of holes at any one time. The degree of control of the thrust differential between the different nozzles .in this modification will therefore be less than that obtainable with the construction shown in FIGURES 1 and 2. Since the details of the FIGURES 3 and 4 construction are otherwise the same as the FIGURES l and 2 construction, land the operation differs only in the partial or complete blocking of only one :hole at a time instead of more as shown in FIGURES 1 and 2, they will not be repeated.

While only one rotating blockage member is shown, it will be clear that it is within they scope of the invention to provide two gas blocking membersl movable either as a unit or separably to block two clusters of holes at any one particular time to obtain even more finite attitude control. Furthermore, it will be clear that more or less than three clusters of gas outlet holes 14, and more or less than three holes in any one cluster could be provided without departure from the scope of the invention as long as the desired thrust differential is obtainable. It will also be clear that other forms of nozzles could be used with the gas blockage plate shown to obtain guidance control in a similar manner without departing from the scope of the invention, such as, for example, nozzles not having plug type inlets. Also, the inlet portion of the nozzles could project into the chamber defined by the rocket casing instead of being secured at their inlet ends to the closure plate as shown.

While the invention has been illustrated in this particular instance `for use with a rocket motor, it will be clear that it could be used in many other installations and that many modifications may be made thereto without departing from the scope of the invention.

From the foregoing, therefore, it will be seen that the invention provides a guidance system for .a missile or the like wherein nite attitude control of the missile is available by means of a simple mechanism controlling the exhaust stream in such a manner as to provide a jet turning force on the rocket. It will also be seen that the invention provides a reliable and practical rocket guidance control while being economical to manufacture and simple in structure.

I claim:

1. An exhaust nozzle for a fluid reaction motor duct comprising a closure member secured to and across the outlet end of said duct having clusters of axially directed fluid jet exhaust openings therein, a plurality of iluid jet exhaust nozzles of the converging-diverging type secured to said member each over a separate cluster of said openings for the passage of exhaust iluid therethrough, the nozzles being similarly sized and uniformly distributed around the closure member to impart substantially equal increments of thrust to said motor in a substantially axial direction upon the full flow of exhaust uid through each of said nozzles, the total area of each cluster of said openings being approximately twice the throat area of the corresponding exhaust nozzle, and control means secured to said motor and movable throughout a range of positions to variably control the flow of fluid through selective ones of said nozzles providing a thrust differential between the flow of fluid through lthe nozzles effecting a jet turning force on said duct providing attitude control thereof, each of said nozzles having Ia plug type inlet and a single outlet, the plug type inlet and the outlet together with the closure member openings for each nozzle constituting a plurality of tubular passages equi-angularly disposed and equally spaced with respect to each other and to the longitudinal laxis of said nozzle at one end, the opposite ends of the tubular passages meeting at a common vertex at the throat of said nozzle providing a kinetic convergence of the fluid ow through said passages at said throat, said control means being movable to variably cover one of the openings of the inlet of one of said nozzles, the exhaust uid passing through the uncovered holes and out through the nozzle outlet with an overall reduction in the thrust imparted by the uid passing through the one nozzle.

2. An exhaust nozzle for a fluid reaction motor duct comprising a closure member secured to and across the outlet end of said duct having clusters of axially directed fluid jet exhaust openings therein, a plurality of fluid jet exhaust nozzles of the converging-diverging type secured to said member each over a separate cluster of said openings, for the passage of exhaust fluid therethrough, the nozzles being similarly sized and uniformly distributed around the closure member to impart substantially equal increments of thrust to said motor in a substantially axial direction upon the full flow of exhaust fluid through each of said nozzles, the total area of each cluster of said openings being approximately twice the throat area of the corresponding exhaust nozzle, and control means secured to said motor and movable to variably control the flow of fluid through selective ones of said nozzles providing a thrust differential between the flow of uid through the nozzles effecting a jet turning force on said duct providing attitude control thereof, each of said nozzles having a plug type inlet and a single outlet, the plug type inlet and the outlet together with the openings for each nozzle constituting a plurality of tubular passages equi-angularly disposed and equally spaced with respect to each other and to the longitudinal axis of said nozzle at one end, the opposite ends of the tubular passages meeting at -a common vertex at the throat of said nozzle providing a kinetic convergence of the iiuid ow through the passages at said throat, said control means being movable throughout a range of positions variably and cumulatively covering one or more of the openings into the inlet of one of said nozzles.

References Cited by the Examiner UNITED STATES PATENTS 2,612,747 10/1952 Skinner 60-35.6 2,692,475 lO/ 1954 Hull -35.54 3,026,806 3/l962 Runton et al 60-35.6 3,069,852 12/1962 Stricker 60-35.55

FOREIGN PATENTS 890,502 11/1943 France. 1,025,715 l/1953 France.

MARK NEWMAN, Primary Examiner SAMUEL LEVINE, Examiner.

Claims (1)

1. AN EXHAUST NOZZLE FOR A FLUID REACTION MOTOR DUCT COMPRISING A CLOSURE MEMBER SECURED TO AND ACROSS THE OUTLET END OF SAID DUCT HAVING CLUSTERS OF AXIALLY DIRECTED FLUID JET EXHAUST OPENINGS THEREIN, A PLURALITY OF FLUID JET EXHAUST NOZZLES OF THE CONVERGING-DIVERGING TYPE SECURED TO SAID MEMBER EACH OVER A SEPARATE CLUSTER OF SAID OPENINGS FOR THE PASSAGE OF EXHAUST FLUID THERETHROUGH, THE NOZZLES BEING SIMILARLY SIZED AND UNIFORMLY DISTRIBUTED AROUND THE CLOSURE MEMBER TO IMPART SUBSTANTIALLY EQUAL INCREMENTS OF THRUST TO SAID MOTOR IN A SUBSTANTIALLY AXIAL DIRECTION UPON THE FULL FLOW OF EXHAUST FLUID THROUGH EACH OF SAID NOZZLES, THE TOTAL AREA OF EACH CLUSTER OF SAID OPENINGS BEING APPROXIMATELY TWICE THE THROAT AREA OF THE CORRESPONDING EXHAUST NOZZLE, AND CONTROL MEANS SECURED TO SAID MOTOR AND MOVABLE THROUGHOUT A RANGE OF POSITIONS TO VARIABLY CONTROL THE FLOW OF FLUID THROUGH SELECTIVE ONES OF SAID NOZZLES PROVIDING A THRUST DIFFERENTIAL BETWEEN THE FLOW OF FLUID THROUGH THE NOZZLES EFFECTING A JET TURNING FORCE ON SAID DUCT PROVIDING ATTITUDE CONTROL

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