GB2265342A

GB2265342A - Controlling a projectile about its three axes of roll, pitch and yaw

Info

Publication number: GB2265342A
Application number: GB8809391A
Authority: GB
Inventors: Hubert Barre
Original assignee: Thomson Brandt Armements SA
Current assignee: Thomson Brandt Armements SA
Priority date: 1987-04-22
Filing date: 1988-04-21
Publication date: 1993-09-29
Anticipated expiration: 2008-04-21
Also published as: GB8809391D0; FR2686687A1; IT1237006B; DE3812588A1; GB2265342B; FR2686687B1; SE8801461D0; IT8867332A0

Description

.DTD:

2265342 Method and device for controlling a projectile about its three axes of roll, pitch and yaw The present invention relates to a method and device for controlling a projectile about its three axes of roll, pitch and yale. Such a three- axis control system is applicable to any artillery projectile launched from a tube. Other applications may be envisaged for flying or launched engines that must be directed or oriented along their trajectory. In addition, as the control device does not require any unfolding of air- foils such as wings, it is applicable to any projectile for which the presence of wings, inglets or fins ould complicate the structure and ould be prejudicial to the storage of the projectile or the engine because of being too bulky.

.DTD:

There are numerous systems for controlling engines through gas jets and they allow to produce lateral thrusts from the engine, with particular effects (guidance, control in a plane, etc.). In addition, most of these systems utilize two-state thrusters. The latter allow to apply a thrust F or its oppo- o site -F. These control devices allow, therefore, to produce 0 either a positive or negative force, or a positive or negative torque about a predetermined axis of the engine in question. As this system operates in the on/off mode, it does not allow to apply no effort such as a force or a torque in the absence of command orders.

.DTD:

For example, the French patent application N 2 469 345 describes a method of control and guidance of a projectile in the terminal phase of its trajectory and describes the means utilized in this method. According to this patent application, several longitudinal series of lateral orifices have been provided on the body of the projectile. Each of these orifices is connected to a gas switch, connected itself to a gas generator. To control the trajectory of the projectile, all the switches of one and the same longitudinal row are controlled so as to produce jets of gas in all orifices of one and the same series, thus producing a series of lateral forces oriented in a predetermined direction with respect to the body of the projectile. The longitudinal series to be used to produce the lateral force is determined as a function of the roll attitude of the projectile and of the trajectory correction to be performed.

.DTD:

This system does not allow to orient the projectile about the pitch axis or the yaw axis or the roll axis. It only permits to control the position of the center of gravity of the projectile and thus to modify the trajectory of the latter.

.DTD:

In addition, this system, as well as the other existing systems, does not allow to use a tail to stabilize the engine or to impart it a certain roll motion.

.DTD:

In order to remedy these disadvantages, the present invention proposes a method and a device for controlling about its three axes of roll, pitch and yaw a projectile having its cen- I0 ter of gravity located on its longitudinal axis.

.DTD:

The present invention is characterized by the fact that the method consists in producing, from at least to pairs of points symmetrically disposed about the longitudinal axis in a plane perpendicular to this axis and distant from the center of gravity of the projectile, a force from each of these points, in a direction chosen among two different and predetermined directions, but opposite to both directions of the other point of the same pair. The device uses a gas generator and tóo-state sóitches connected to the gas generator.

.DTD:

The present invention and its features will be better understood from the consideration of the following detailed description given as an example with reference to the accompanying drawings, in which:

.DTD:

- Figure 1 is an explanatory schematic of the principle used in the present invention; - Figure 2 is an explanatory schematic showing the location of an embodiment of a device according to the present invention in a projectile; - Figure 3 is a cross-sectional view of a projectil pesnquipped with an embodiment of a device according to the / invention; Figure 4 is a partial cross-sectional view of a first possible embodiment of a switch which may be used in such a device; - Figures 5a and 5b are two partial cross-sectional views of a second embodiment of a switch 'hioh may be used in/thedevice; - Figures 6 to 21 show the sixteen possible control combinations ich can be implemented ih four sitehes.

.DTD:

--4 - The principle used in the present invention is based on the following observations. The projectile control devices employed to date generally use gas generators to produce forces intended to influence the behaviour of the projectile. The most common of these gas generators use as fuel a solid propellant, whose combustion once started cannot be stopped before the quantity of fuel is fully exhausted. This results in the necessity, once this combustion is started, of providing at least an exhaust orifice permanently for the gas, even if it is not desired to produce a predetermined force at each time. In the case where no modification of trajectory or of attitude is required, it is necessary, in the existing systems, to apply a method of distribution and arrangement of the various forces that can be produced, so that, during a small time unit, the global average of all these forces is zero and that their action has no influence on the projectile. In the case of a projectile equipped with two diametrally opposite nozzles, it is necessary to alternate the exhaust of the gas in an equal manner through one, then through the other of these two nozzles.

.DTD:

The principle utili- zes, therefore, the fact that the flow is permanent and indispensable for the gas generator and also that the flow rate must be constant for the operation to be regular during all the combustion of the fuel. It is thus proposed to use several lateral nozzles that produce each a jet of gas permanently, but also to orient each of these jets so as to either cancel out all forces in the case where no corrective action is needed or, on the contrary, create an unbalance of these }0 forces so that the resultant of these forces, applied to the center of gravity of the projectile, modifies in a predetermined manner the attitude or the trajectory of the projectile.

.DTD:

This principle is illustrated by Figure I in its optimum implementation. The body of a projectile I is shown with two axes YY' and ZZ' intersecting each othe at right angles in the center C of this projectile. Four points P are disposed symmetrically about the center C of the projectile, i.e., they are spaced angularly from each other by 900 and they are distant from the center C by a distance equal to R/2. There is also shown, from each of these four points P, a force with a single value F denoted by a black arrow. For each point P, each force can be oriented along two different directions.

.DTD:

An essential condition is that these directions do not go through the point C located on the longitudinal axis. A second essential condition.... .

.DTD:

is that both directions of the forces from two points opposite with respect to the center C be colinear and opposite two by two. In Figure 1, these directions have been represented orthogonal to each other for each point and parallel to the directions of the remaining points, this with the logical aim of simplification of the problem and efficiency of implementation. The white arrows denote the second position that s force F can have with respect to the same points. It can be seen that, with respect to the point C of the projectile, none of the directions that each of the forces F can have passes through the center of gravity of the projectile. This results in each of the forces exerting a torque about this center of gravity. In Figure I, the directions of the forces F are shown parallel to the axes YY' and ZZ'; this corresponds to the optimum arrangement. If the distance of each point P of application of the forces from the orthogonal axes YY' and ZZ' is equal to R, each force F creates about the point C a torque equal to FxR. This torque results in the projectile 1 pivoting about its longitudinal axis XX', i.e., the roll axis, going through the center of gravity CòWith reference to Figure 2, the system is disposed in the projectile I in a plane AA' orthogonal to the longitudinal axis XX' of the projectile and located at a distance L from the center of gravity G of the projectile. Thus, each force F creates about this center of gravity a second torque equal to FxL. This torque may re- sult in the projectile pivoting about the axis YY' i e the Y 9 pitch axis, or about the axis ZZ', i.e., the yaw axisòTo implement this method of control, the device uses, as shown in Figure 3, a switch 10 at each point P, connected to a gas generator (not shown). This switch has two stable positions allowing to orient the gas from the generator, by means of two nozzles 11a and 11b, either in a direction parallel to the axis YY' or in a direction parallel to the axis ZZ'.

.DTD:

With reference now to Figure 4, a possible embodiment of this switch is shownòIt consists of a cylindrical hole 5 centered on the point P and with a longitudinal axis parallel to that of the projectile. Two nozzles T opening outside have their base 14 opening in the hole 5. In this hole is placed a rotating cylinder 2 in which an opening 3 is madeòThis opening has a width smaller than the distance between the bases of the two nozzles T corresponding to the same point and ending at the cylindrical hole. Therefore, the gas arriving -4 It" O O O " r "7O O. 0 n rr C "l 0 r'r CT.

.DTD:

O. " c- -- Clr (0. 0 0.. 0 N O c" D Q. O. "O "7 D 0. X 0 D O O 0% 0. ZT Cr CI. O O " < 0 0 O::Y N -l " 0 "I (0 1::7 -1 clr - in. D c-r. "I C.C O C". cr. --4. -' c'r Z" "7 -rl r.

- ' (0 r-. ZY I-.. CO r ZY 0::)" "7 0 (0 V r C I. (O -I "I O - 0 X CO X 0 F-'. O 0 "0 I- O.

. ". "I O c4- tO 0 -q 0 I-- CO "I.

.DTD:

0 0 (I) (I) "0 " "7 l-. c".

.DTD:

0 0 0 0 0 D O 0 O rr D.l ZT O -4% C0 0 0 Z) r 0 rr 0 O O 4- C: 0 ZT, c-r(I) 0 - CT - l-. l 0 C m C (/ 0 CO C 0 N 0 l. 0 D D (I) r Z) I- C3" 0 N 0) 0 r 0 0 "< 0 r.. 0 - "0 D l.. r",< E "0 "7 O. -- F.. "0 "0 0 " (. ". 0 I c'v O r" O " CO 4 O "< O 0 O O O. X W " CO 0 O -r -r.,< rv ZT O C0 ' - 14 0 O 0 CO. C rr 0 ( 0 W ":0 O CO C: (0 -I'- c-r" -,.

.DTD:

" 0 0 0 I-." CO " I--. I--' I. ( r or I. (/ 'C (I) 0 0 "0 11) 0 I --.l $ I0 only in roll, and this in both possible directions. The torque has a value equal to 4 FxR.

.DTD:

In figures 8 and 9, the forces along the axis ZZ' cancel each other out, and the forces along the axis YY' add up. There is, therefore, obtained a control action producing a thrust along the axis YY', with a force 2F, and a torque 2FÎL about the axis ZZ'. This corresponds to a control action in yaw only.

.DTD:

In Figures 10 and 11, the forces F cancel each other out along the axis YY' and add up along the axis ZZ'. There is, therefore, produced a force equal to 2F along the axis ZZ' and a torque equal to 2FxL about the axis YY'. This corresponds to control in pitch only.

.DTD:

In Figure 12, all the forces cancel each other out along the axis YY'. There is thus obtained no force and no torque applied to the center of gravity C. In Figure 1), the same is true along the axis ZZ'. These two Figures 12 and 13 correspond, therefore, to zero control, i.e., to a situation without control.

.DTD:

The eight Figures 14 to 21 correspond to eight situations in which there is a combination of controi in oll, with a torque 2FÎR, and a torque in pit=h and a torque in yaw, with a value equal to FxL for each.

.DTD:

Figures 14 and 15 correspond to yaw control in a first direction associated with roll and pitch control in either of the two possible directions.

.DTD:

Figures 16 and 17 also correspond to yaw control but in the direction opposite to both preceding Figures, in combination with roll control in both possible directions.

.DTD:

Figures 18 and 19 correspond to pitch control in a first direction, in combination with both possible directions of roll and yaw control.

.DTD:

I0 Finally, Figures 20 and 21 also correspond to pitch control but in the direction opposite to that of both preceding Figures, in combination with the two possible control directions in roll and in yaw.

.DTD:

In these eight Figures 14 to 21, control in yaw and in pitch is performed with a single unit of force F, unlike the four Figures 8, 9, 10 and 11. In the same way, according to these Figures, the value of the roll torque corresponds to two units FxR, whereas according to Figures 6 and 7, the torque corresponds to four units FxR.

.DTD:

Thus, if we denote by:

.DTD:

CRn = 2FxR C = FxL Tn CLn = FxL, the nominal unit torques available for each axis of roll, pitch and yaw, respectively, and if we denote by CR, CT and CL the torques effectively exerted about theses axes depending on the configurations, we can write the following ratios:

.DTD:

JR = CR/CRn' L = CL/CLn' T = CT/CTn Using these notations, the sixteen combinations offered are described by the table given in Annex with reference to Figures 6 to 21 commented above.

.DTD:

The advantages offered by the device described above are the following:

.DTD:

- the implementation is relatively simple since it requires only four simple and identical two-state switches. The device appears, therefore, relatively reliable and simple; - the flow cross-section for the gas is constant, whatever the configuration chosen among the sixteen possibilities. This permits optimum and predetermined operation of the gas generator; - 10,- - the sixteen different modes of operation allows either not to control the projectile about an axis or to control it with a unit of force F or a unit of two forces F, and this in both possible directions; - the availability of a double torque about a given axis permits to counter significant and occasional disturbances. It also allows a sudden modification of the trajectory of the projectile, for example when it is necessary to hit a target moving aside at the last time of the trajectory of the projectile.

.DTD:

A particular application of the present invention provides a reduced number of possibilities of coupling between the switches. The latter are, for example, two or three in number. This obviously reduces the number of possibilities and this number may be reduced to two, four or eight possibilities. This solution may be interesting for projectiles of simple design that have no requirements for significant and rapid corrections of trajectory. It is also possible to povide a greater number of points P from which the forces F are produced. For example, there can be provided eight switches disposed with a 45o spacing to be able to modulate the forces or torques from zero to four units of forces F. Moreover, the precision of the orientation in roll can thus be increased.

.DTD:

+ + i I + I I + + I + I + + I I = -- = -- = :3 0 r' "0 o o I c3 (:3 (:3 Z o o o 3 r o E3 (:3 O Z o o "7 O C3 + r,a E3 (:3 I (:3 "0 rf r) :3" oo (:3 (:3 + ha -..I C3 E3 I rJ = o I o o + o o o o z o r- U3 E o ::0 o co E" r3 :D x (-r w o" ! i .CLME:

Claims

Claims .CLME:

I0 1. A method for controlling about three axes of roll (XX'), yaw (ZZ') and pitch (YY') a projectile with a longitudinal axis (XX') and a center of gravity located on said longi- tudinal axis, consisting in producing from at least a pair of points located symmetrically about said longitudinal axis in a plane perpendicular to said longitudinal axis and distant from said center of gravity of said projectile, a force with a single value from each said point in a di- rection chosen among two directions, different, predetermined and opposite to both directions of the other point of the same pair and not going through said longitudinal axis.

.CLME:

2. A method according to claim 1, wherein said points from which are produced said forces are four in number and are angularly spaced by 90 from each other.

.CLME:

5. A device for controlling about the three axis of roll (XX'), yaw (ZZ') and pitch (YY') of a projectile with a lon- gitudinal axis (XX') and a center of gravity located on said longitudinal axis, for the implementation of the method according any of claims 1 and 2, including at least a gas generator, said device comprising, located in two points of one and the same pair of points and symmetrically about said longitudinal axis of said projectile in said plane at least a pair of switches connected to said gas generator and each being capable of orienting a jet of gas in a first direction or in a second direction among said two directions, determined, different and opposite to both directions of the other switch of the same pair, and not going through said longitudinal axis of said projectile.

.CLME:

4. A device according to claim 3, wherein said switches are each made up of a cylinder capable of pivoting within a hole in said projectile about said point and having an opening allowing to exhaust the gas from said gas generator through either of two corresponding nozzles by rotation of said cylinder.

.CLME:

5. A device according to claim 3, wherein each switch is made up of a cylinder having two openings shifted angularly about said longitudinal axis by an angle corresponding to the angle formed by the two directions of two corresponding nozzles also shifted longitudinally so that, through translation, said cylinder exhausts said gas from said gas generator only through either nozzle.

.CLME:

6. A method for controlling about three &xes of roll (2'), yacht (ZZ') and pitch (YY') a projectile ith a longitudinal axis (3X) substantially as hereinbefore described.

.CLME:

7. A device for controIIing about three axes of roll (LY'), ya (ZZ') and pitch (YY') a projectile ith a longitudinal axis (NLX,) substantially as hereinbefore described ith reference to the accompanying drazings.

.CLME:

Amendments to the claims have been filed as follows L.

Claims i. A method for controlling about three axes of roll (XX'), yaw (ZZ') and pitch (YY') a projectile with a longitudinal axis (XX') and a center of gravity (G) located on said longitudinal axis (XX'), consisting in producing, from at least two pairs of points (P), the points in each pair being symmetrically located with respect to said longitudinal axis, located in a plane (AA') perpendicular to said longitudinal axis and distant from said center of gravity of said projectile, a force with a single value (F) from each said point in a direction chosen among two different directions, one being parallel to the axis (ZZ'), the other being parallel to the axis (YY'), the directions parallel to the same axis (ZZ') or (YY') for two points of the same pair being opposite, and not passing through said longitudinal axis (XX').

.CLME:

2. A method as claimed in claim I, wherein said points from which are produced said forces are regularly angularly spaced out from each other.

.CLME:

3. A method as claimed in claim 2, wherein said points from which are produced said forces are angularly spaced by 90 from each other.

.CLME:

4. A device for controlling a projectile, with a longitudinal axis (XX') and a center of gravity (G) located on said longitudinal axis, about three axes of roll (XX'), yaw (YY'), and pitch (ZZ'), said device being arranged for implementation of the method of claim I, 2 or 3 and including:

.CLME:

a gas enerator, and a plurality of switches, each said switches located at one of said points and coupled to said gas enerator, each said switch having a pair of outlets, one outlet in each of said first and second directions and directing Gas from said as generator in one of said first and second directions.

.CLME:

I0 5. A device according to claim 4, wherein said swit=hes ae each made up of a cylinder capable of pivoting within a hole in sald projectile abouúsaid point and having an opening allowing to exhaust the gas From said gas generator through elthe of two corresponding nozzles by rotation of said cylindec.

.CLME:

6. A device according to claim 4, wherein each switch is made up of a cylinder having two openings shifted angularly about said [ongltudinal axis by an angle corresponding to the angle Formed by the two directions of two corresponding nozzles also shifted longitudinally so that, through translation, said cylinder exhausts said gas from said gas generator only through either of tóo corresnonding nozzles.

.CLME:

7. A method for controlling about three es of roll (,), ya (ZZ') and pitch (YY,) a projectile ith a longitudinal axis (') substantially as hereinbefore described.

.CLME:

8. A device for controlling about three xes of roll (}'), yale (ZZ') and pitch (Yy,) a projectile ith a longitudinal axis (') substantially as hereinbefore described:ith reference to the accompanying draóings.

.CLME: