WO2014178045A1

WO2014178045A1 - Steering system and method

Info

Publication number: WO2014178045A1
Application number: PCT/IL2014/050382
Authority: WO
Inventors: Moshe Tsabari; Doron BAR ANAN
Original assignee: Israel Aerospace Industries Ltd.
Priority date: 2013-04-29
Filing date: 2014-04-24
Publication date: 2014-11-06
Also published as: IL226044B

Abstract

A steering system (100) is provided for a body (10) configured for moving through a fluid medium. The steering system has a longitudinal axis (B) and includes a fluid deflector apparatus (200), a mounting arrangement (400), and a control system (600). The fluid deflector apparatus (200) defines at least a part of an external casing (299) of the steering system (100), and includes a ram inlet (210), an exhaust outlet (230) defined on the external casing and laterally disposed with respect to the longitudinal axis, and an internal fluid passageway (270) extending between the ram inlet and the exhaust outlet. The internal fluid passageway is immovably positioned with respect to at least the exhaust outlet. The mounting arrangement is configured for rotatably mounting the fluid deflector apparatus with respect to the body about the longitudinal axis. The control system is configured for selectively providing and maintaining a desired angular disposition of the fluid deflector about the longitudinal axis.

Description

STEERING SYSTEM AND METHOD

TECHNOLOGICAL FIELD

The presently disclosed subject matter relates to steering systems, in particular for steering bodies travelling through a fluid medium.

PRIOR ART

References considered to be relevant as background to the presently disclosed subject matter are listed below:

- US 8,080,771 Shai

- US 4,685,639 Bains

- US 4,681,283 Kranz

- US 4,537,371 Lawhorn et al.

- US 4,522,357 Bains

- US 4, 193,567 McCarty Jr.

- US 4, 128,060 Gawlick et al.

- US 3,977,629 Tubeuf

- US 3,325, 121 Banaszak et al.

- US 3,208,383 Larson

- WO 2006/103647

Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.

BACKGROUND

It is known to provide lateral steering control to bodies moving through a fluid medium, such as air for example. In some cases, such as for example projectiles, such control allows for correction of aiming errors, for maneuvering, and for compensation for wind deflection.

It is also known to provide such lateral steering via jet thrust control, in which a lateral jet thruster arrangement provides a side thrust to the projectile. Many lateral steering systems based on jet thrust techniques are known, some of which are disclosed in at least some of the above references.

GENERAL DESCRIPTION

According to an aspect of the presently disclosed subject matter there is provided a steering system for a body configured for moving through a fluid medium, the steering system having an external casing and a longitudinal axis and comprising: fluid deflector apparatus defining at least a part of said external casing, and including a ram inlet, an exhaust outlet defined on said external casing and laterally disposed with respect to the longitudinal axis, and an internal fluid passageway extending between said ram inlet and said exhaust outlet, wherein said internal fluid passageway is immovably positioned with respect to at least said exhaust outlet; mounting arrangement configured for rotatably mounting the fluid deflector apparatus with respect to the body about the longitudinal axis; and control system configured for selectively providing and maintaining a desired angular disposition of the fluid deflector about the longitudinal axis.

In at least some examples, said internal fluid passageway is immovably positioned with respect to said ram inlet.

Additionally or alternatively, said internal fluid passageway has a fixed spatial disposition with respect to at least the exhaust outlet at least during steering mode operation of the steering system wherein fluid from the fluid medium is passing through said internal fluid passageway. Additionally or alternatively, said internal fluid passageway has a fixed spatial disposition with respect to the ram inlet.

Additionally or alternatively, the exhaust outlet is in permanent fluid communication with the ram inlet via said internal fluid passageway.

Additionally or alternatively, said exhaust outlet is permanently open to the fluid medium at least when the steering system is travelling through the fluid medium.

Additionally or alternatively, in operation of the steering system in said steering mode to provide selective lateral steering control to the body, fluid from said fluid medium is continuously channeled through said fluid deflector apparatus from said ram inlet to said exhaust outlet and out of said exhaust outlet via a fixed fluid path defined by said internal fluid passageway.

Additionally or alternatively, responsive to the steering system moving through the fluid medium, fluid from said fluid medium is continuously channeled through said fluid deflector apparatus from said ram inlet to said exhaust outlet and out of said exhaust outlet via a fixed fluid path defined by said internal fluid passageway.

Additionally or alternatively, responsive to said steering system moving through the fluid medium, fluid from said fluid medium is continuously channeled through said fluid deflector apparatus to continuously generate a side force.

Additionally or alternatively, said control system is configured for selectively providing a continuous uniform rotation of the fluid deflector apparatus about the longitudinal axis while said steering system is moving through the fluid medium, the fluid from said medium being continuously channeled through said fluid deflector apparatus to generate a zero net side force integrated over each full revolution of the fluid deflector apparatus about said longitudinal axis, in particular wherein the rotation is at a constant rotational speed.

Additionally or alternatively, said internal fluid passageway is configured for turning the flow from a generally axial direction to a generally lateral direction by a flow turning angle. For example, said flow turning angle has a value of about 90°, or about 80° or about 85°, or about 95° or about 110°, or in the range between about 75° and 115°, or in the range between about 80° and 110°, or in the range between about 85° and 105°, or in the range between about 90° and 100°; wherein any of such values for the flow turning angle can be within ±5°, or preferably within ±4°, or preferably within ±3°, or preferably within ±2°, or preferably within ±1°, of the stated values.

Additionally or alternatively, said internal fluid passageway comprises an elbow duct. At least the elbow duct is immovably positioned with respect to the exhaust outlet. Optionally the elbow duct is immovably positioned with respect to the ram inlet and the exhaust outlet.

Additionally or alternatively, said internal fluid passageway comprises one or a plurality of fluid turning vanes for facilitating turning the flow through said internal fluid passageway.

Additionally or alternatively, the steering system comprises a centerbody provided in said internal fluid passageway in proximity to said ram inlet. For example, said centerbody is in fixed spatial relationship with respect to said ram inlet. For example, is immovably connected to said internal fluid passageway; alternatively, said centerbody is movably connected to said internal fluid passageway; for example said centerbody is axially movable with respect to said ram inlet.

Additionally or alternatively, a first ratio between an inlet area associated with said ram inlet and an outlet area associated with said exhaust outlet is 1.1.

Additionally or alternatively, a first ratio between an inlet area associated with said ram inlet and an outlet area associated with said exhaust outlet is in a range 1.1 to 3.

Additionally or alternatively, said mounting arrangement comprises a bearing structure for mounting the steering system to the body thereby.

Additionally or alternatively, said mounting arrangement is configured for allowing free pivoting of said steering system with respect to the body when mounted thereto. Additionally or alternatively, said mounting arrangement is configured for providing decoupling rotation of said steering system about said longitudinal axis with respect to the body when mounted thereto.

Additionally or alternatively, said mounting arrangement is configured for enabling the steering system to be retrofittably mounted to the body, the body being in the form of a projectile.

Additionally or alternatively, said mounting arrangement is configured for enabling the steering system to be retrofittably mounted to the body, the body having an aerodynamically contoured nose portion. For example, said mounting arrangement is configured for enabling the steering system to be retrofittably mounted to the nose portion of the body.

Additionally or alternatively, the control system comprises at least one control vane pivotably mounted at said exhaust outlet. For example said at least one control vane is pivotable about a pivot axis about a vane deflection angle; for example said pivot axis is generally parallel to said longitudinal axis. For example said at least one control vane is pivotable between a datum said vane deflection angle and at least one of a maximum said vane deflection angle or a minimum said vane deflection angle. For example, at said datum vane deflection angle, said at least one control vane presents a minimum cross- section to fluid flow passing through said internal fluid passageway; alternatively, for example, at said datum vane deflection angle, said at least one control vane provides a tangential force and corresponding roll moment to the steering system complementary to a frictional moment that can be generated resulting from a relative rotation between the steering system and the body. For example, the control system is configured to operate such that at said datum vane deflection angle, said at least one control vane is prevented from tangentially diverting fluid flow passing out of said exhaust outlet.

Additionally or alternatively, at a respective said vane deflection angle greater or smaller than said datum vane deflection angle, said at least one control vane tangentially diverts fluid flow passing out of said exhaust outlet to generate a correspondingly positive or negative roll moment and to thereby provide said desired angular disposition of the fluid deflector about the longitudinal axis.

Additionally or alternatively, the control system is configured for providing a respective said vane deflection angle greater or smaller than said datum vane deflection angle, wherein said at least one control vane tangentially diverts fluid flow passing out of said exhaust outlet to generate a correspondingly positive or negative roll moment to thereby provide said desired angular disposition of the fluid deflector about the longitudinal axis, and wherein the control system is further configured for subsequently providing a respective said vane deflection angle equal to said datum vane deflection angle to selectively maintain said desired angular disposition.

Additionally or alternatively, at said maximum vane deflection angle and/or at said minimum vane deflection angle, said at least one control vane presents a generally maximum cross-section to fluid flow passing through said internal fluid passageway.

Additionally or alternatively, a second ratio of the outlet area associated with the exhaust outlet to a plan area of the at least one control vane is greater than 1.0.

Additionally or alternatively, a third ratio of a plan area of the at least one control vane to the outlet area associated with the exhaust outlet is in the range 0.1 to 0.9. In at least some examples, the third ratio can depend on the friction of the bearing(s) and/or the desired roll rate.

Additionally or alternatively, a fourth ratio of a duct cross-sectional area associated with the elbow duct (or part thereof, for example at a point along the centerline of the elbow duct, taken between the ram inlet and the exhaust outlet, said point being intermediate between the center of the centerline and the ram inlet) to the inlet area associated with the ram inlet is greater than 1.0. For example, a portion of the elbow duct abutting the ram inlet and extending downstream thereof can incorporate a diffuser arrangement. Additionally or alternatively, said fluid medium is air, and for example the body is a projectile or other air vehicle. Alternatively, the fluid medium is water, and for example the body is a torpedo or other water craft.

According to this aspect of the presently disclosed subject matter there is also provided a vehicle comprising a body and a steering system mounted to the body, the steering system being as defined herein according to the aforesaid aspect of the presently disclosed subject matter. For example, the body is elongate having a body longitudinal axis, and wherein said longitudinal axis of said steering system is co-axial with said body longitudinal axis.

According to this aspect of the presently disclosed subject matter there is also provided a method for steering for a body moving through a fluid medium, comprising :

(a) providing a steering system as defined herein according to the aforesaid aspect of the presently disclosed subject matter, and

(b) operating the steering system to provide a side force at a desired angular disposition of the fluid deflector about the longitudinal axis.

Features of the steering system according to at least some examples of the presently disclosed subject matter can include one or more of the following: relatively simple construction;

lightweight construction;

robust structure;

fast dynamic response;

maximization of side force magnitude;

large side force magnitude to weight or volume ratio;

allows for retrofit on existing vehicles such as projectiles for example;

can allow retrofit on some projectiles by replacing the fuse with the steering system;

the entire steering system can be located at the front end of a vehicle, providing compactness. Another feature of the steering system according to at least some examples of the presently disclosed subject matter can include incorporating the control system in the steering system itself and/or directly actuating the control system in the form of a vane or the like, wherein the vane operates to divert only a small portion of the fluid medium that is flowing through the internal fluid passageway. This enables a fast dynamic response of the steering system to actuation of the vane due to the relatively small moment of inertia of the steering system, for example as compared with that of the body. Without being subject to theory, inventors consider that such a control system can provide a roll control for the steering system that is effectively decoupled from the side force actually being generated by steering device, enabling the aforesaid fast dynamic response.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, examples will now be described, by way of non- limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 is a front view of a first example of the steering device according to the presently disclosed subject matter.

Fig. 2 is a bottom view of the example of Fig. 1.

Fig. 3 is a cross-sectional side view of the example of Fig. 1 taken along W-W.

Fig. 4 is a cross-sectional side view of the example of Fig. 1 taken along E-E.

Fig. 5 is a cross-sectional isometric view of the example of Fig. 1 taken along W- W.

Fig. 6 is a cross-sectional isometric view of the example of Fig. 1 taken along E- E; Fig. 6(a) illustrates the relationship between side thrust, tangential forces and roll angle.

Fig. 7 is a cross-sectional front view of the example of Fig. 2 taken along H-H. Fig. 8 is a partially fragmented isometric view of the example of Fig.1, mounted onto a projectile.

Fig. 9 is a partially fragmented isometric view of a second example of the steering device according to the presently disclosed subject matter, retrofitted onto a projectile.

DETAILED DESCRIPTION OF EXAMPLES

Referring to Figs. 1 to 8, a steering system for a body 10 moving through a liquid medium M according to a first example of the presently disclosed subject matter, generally designated 100, comprises a fluid deflector apparatus 200, a mounting arrangement 400, and a control system 600.

The body 10 comprises a longitudinal axis A. In this example, and referring to Fig. 8, body 10 is in the form of a projectile having a front end 11 and tail 12, and the fluid medium M is air. However, in alternative variations of this example, the fluid medium is a liquid such as water for example, and the body can be in the form of a torpedo, submarine or other water vehicle, for example.

Further in this example, the projectile is spin stabilized and thus spins about the longitudinal axis A as it travels through the atmosphere, for example via curved spin fins 15. However, in alternative variations of this example the projectile can be fin- stabilized instead, and is not required to spin about the longitudinal axis A as it travels through the atmosphere. In any case, the projectile can optionally include a propulsion system, for example a rocket engine or a ramjet or other jet engine, to provide propulsion through the atmosphere, and/or can have forward momentum provided by an external system independent of the projectile, for example by being fired from a cannon or mortar, or gravitationally by being dropped from a carrier aircraft at altitude, for example. In this example, the projectile is unmanned and can carry a payload, for example explosives or surveillance equipment, but in alternative variations of this example the body can comprise a manned vehicle and/or can optionally carry similar or different payloads. The fluid deflector apparatus 200 comprises an external or outer casing 290, and an internal fluid passageway 270. The outer casing 290 defines at least a part of the external casing 299 of the steering system 100, and in this example has a general cylindrical form. The external casing 299 of the steering system 100, and in particular outer casing 290, are in direct contact with the external fluid medium flowing over an outside of the steering system when the steering system 100 is moving through the fluid medium.

The internal fluid passageway 270 defines a fixed fluid passageway for a stream of said fluid medium that flows into and through the fluid deflector apparatus 200 during operation of the steering system 100.

Referring in particular to Figs. 1 to 7, the fluid deflector apparatus 200 has a longitudinal axis B that is generally co-axial with, or is at least generally parallel to, longitudinal axis A when the system 100 is mounted to body 10. For example, longitudinal axis B can be considered to be generally parallel to (or generally co-axial with) longitudinal axis A, while actually being angularly displaced by a small angular displacement with respect to longitudinal axis A (as defined on any plane on which lie longitudinal axis A and longitudinal axis B) from 0° up to ±10°, or preferably from 0° up to ±9°, or preferably from 0° up to ±8°, or preferably from 0° up to ±7°, or preferably from 0° up to ±6°, or preferably from 0° up to ±5°, or preferably from 0° up to ±4°, or preferably from 0° up to ±3°, or preferably from 0° up to ±2°, or preferably from 0° up to ±1°, or preferably from 0° up to ±0.5°. For example, such angular displacements can include typical variations and/or variations to these numerical values.

The fluid deflector apparatus 200 comprises a ram inlet 210 at the front end 201 thereof, generally aligned with longitudinal axis B, and an exhaust outlet 230 laterally disposed with respect to the longitudinal axis B. The internal fluid passageway 270 comprises an elbow 240 that connects ram inlet 210 to exhaust outlet 230 and provides permanent fluid communication between the ram inlet 210 and the exhaust outlet 230.

The exhaust outlet 230 is defined on said outer casing 290, and thus on said external casing 299. Referring to Fig. 1, the steering system 100, and in particular the fluid deflector apparatus 200, comprises a maximum cross section area AC taken on a plane orthogonal to axis B.

The ram inlet 210 comprises an inlet edge 212 or lip, provided on the outer casing 290 and that in this case is generally circular, as best seen in Fig. 1. The ram inlet 210 defines an inlet area AI (Fig. 3). The inlet edge 212 defines the upstream end of the internal air passageway 270.

The exhaust outlet 230 is provided on the side of outer casing 290, and in this case is generally oval, comprising an outlet edge 232. The exhaust outlet 230 defines an outlet area AO (Fig. 3). The outlet edge 232 defines the downstream end of the internal air passageway 270.

Elbow 240 is configured for turning the flow by turning angle Θ in the internal air passageway 270, from a generally axial direction at the ram inlet 210 generally aligned or parallel with longitudinal axis B (and thus axis A), to a general radial or lateral direction T, at the exhaust outlet 230. As best seen in Fig. 3, the turning angle Θ is defined with reference to an imaginary plane PL, wherein axis B and the centre CI of ram inlet 210 (and preferably also the center C2 of exhaust outlet 230) all lie on plane PL (Figs. 1, 5).

In this example, the turning angle Θ is 90°, and thus the flow is directed to exit the exhaust outlet 230 in the lateral direction T generally orthogonal to axis B to provide a corresponding thrust vector VR_T in the lateral direction T. However, and as best seen in Fig. 4, in alternative variations of this example, the turning angle Θ can be different from 90°, greater than 90° or less than 90°, for example turning angle Θ can be 75°, or 80°, or 85°, or 95° or 100° or 115°, and thus the flow is directed to exit the exhaust outlet 230 with a flow direction Tl angularly offset from direction T, to provide a flow and corresponding total thrust vector VR having a major thrust vector component VR_T in lateral direction T generally orthogonal to axis B, as well as a minor thrust vector component VR_B in the axial direction (forward or aft) along axis B. In this example, the elbow 240 comprises an internal curved duct 245, generally symmetrical about plane PL, and having an elbow-shaped duct wall 249 including an outer curved wall portion 241 and an inner curved wall portion 243 when viewed from the side, as in Fig. 3. However, in alternative variations of this example, the elbow 240 can instead comprise, for example, a plenum chamber arrangement having an inlet at the ram inlet 210 and an outlet at the exhaust outlet 230 (optionally omitting curved walls), and an intermediate plenum chamber; the flow through the fluid deflector apparatus 200 is compelled to change direction by turning angle Θ because of the spatial relationship between the ram inlet 210 and the exhaust outlet 230.

In this example, at least a downstream portion 248 of the duct wall 249 continuously extends to, and/or is physically connected to, the exhaust outlet 230. In this example, at least the downstream portion 248 of the duct wall 249 has a fixed spatial orientation with respect to the exhaust outlet 230. In this example, at least the downstream portion 248 of the duct wall 249 is rigidly fixed with respect to the exhaust outlet 230. The downstream portion 248 of the duct wall 249 can be defined as where a majority of the flow turning occurs in the fluid deflector apparatus 200. In this example the downstream portion 248 includes outer turning curved wall portion 241 and inner curved wall portion 243.

In this example the internal fluid passageway 270 is immovably positioned with respect to at least said exhaust outlet 230.

In this example the internal fluid passageway 270 is immovably connected to at least said exhaust outlet 230.

In this example the internal fluid passageway 270 has a fixed spatial disposition, in particular a fixed orientation, with respect to at least the exhaust outlet 230, particular in operation of the system 100 in steering mode.

In this example, the duct wall 249 extends continuously between, and/or is physically connected to, the exhaust outlet 230 and the ram inlet 210. In this example the internal fluid passageway 270 has a fixed spatial orientation with respect to the exhaust outlet 230 and the ram inlet 210. In this example, the duct wall 249 is rigidly fixed with respect to the exhaust outlet 230 and the ram inlet 210.

In alternative variations of this example the respective fluid deflector apparatus 200 is configured for permitting relative rotation between a forward portion of the internal fluid passageway 270 including the ram inlet 210 and the remainder of the internal fluid passageway 270.

In this example, the duct wall 249 maintains a fixed geometry of the internal fluid passageway 270 between the ram inlet 210 and the exhaust outlet 230, irrespective of and independently of the roll angle γ of the fluid deflector apparatus 200 with respect to axis A or axis B. In particular, the downstream portion 248 of the duct wall 249, including outer turning curved wall portion 241 and an inner curved wall portion 243 are in fixed geometrical relationship with the exhaust outlet 230, and in this example also in fixed geometrical relationship with the ram inlet 210.

In this example, the duct wall 249 maintains a fixed spatial relationship of the internal fluid passageway 270 between the ram inlet 210 and the exhaust outlet 230, irrespective of and independently of the roll angle γ of the fluid deflector apparatus 200 with respect to axis A or axis B. In particular, the downstream portion 248 of the duct wall 249, including outer turning curved wall portion 241 and an inner curved wall portion 243 are in fixed spatial relationship with the exhaust outlet 230, and in this example also in fixed spatial relationship with the ram inlet 210.

Elbow duct 240 comprises a generally circular cross section at each plane taken orthogonally to the centerline C thereof, though in alternative variations of this example these cross-sections can have any other suitable shape, for example polygonal (including square, rectangular, hexagonal, octagonal etc), oval, elliptical super elliptical, etc. In this example, an upstream portion of the elbow duct 240 can comprise a cross-sectional distribution, in which the cross section at each plane taken orthogonally to centerline C increases with distance downstream from the ram inlet 210 for an upstream duct portion, for example up to a mid portion of the elbow duct 240. For example, this is accomplished by incorporating a diffuser arrangement in this upstream portion. In any case, the cross- sectional area of the duct decreases at least in proximity to the exhaust outlet 230.

In alternative variations of this example, the cross-sectional distribution of elbow duct 240 can be constant or decrease downstream from the ram inlet 210, until at least close to the exhaust outlet 230.

In this example, and referring in particular to Fig. 3, the fluid deflector apparatus 200 further comprises an inlet centerbody 280, including a conical-shaped or ogive-shaped nose 281 projecting forward of the inlet edge 212, a main body 283, and an aft end 285. The centerbody 280 has an axis BB generally parallel to axis B but offset therefrom on plane PL, and the centerbody 280 concentrically positioned with respect to the ram inlet 210. For example, axis BB can be considered to be generally parallel to longitudinal axis B, while actually being angularly displaced by a small angular displacement with respect to longitudinal axis B (as defined on any plane on which lie longitudinal axis B and axis BB) from 0° up to ±10°, or preferably from 0° up to ±9°, or preferably from 0° up to ±8°, or preferably from 0° up to ±7°, or preferably from 0° up to ±6°, or preferably from 0° up to ±5°, or preferably from 0° up to ±4°, or preferably from 0° up to ±3°, or preferably from 0° up to ±2°, or preferably from 0° up to ±1°, or preferably from 0° up to ±0.5°. For example, such angular displacements can include typical variations and/or variations to these numerical values.

The inlet area AI of the ram inlet 210 in this example is generally annular, defined between the inlet edge 212 and the surface of the nose 281.

Optionally, the nose 281 can comprise communications antenna (not shown), for example for receiving signals from a GPS system and/or for transmitting and/or receiving signals and/or data.

The main body 283 defines an internal space, which in this example is optionally used for accommodating a battery 610 for powering the system 100, in particular the control system 600. The aft end 285 has an external curved shape to assist in turning the flow through the internal fluid passageway 270.

In this example, the fluid deflector apparatus 200 further comprises turning vanes 220 configured for assisting in turning the flow through the internal fluid passageway 270 see Figs. 1, 4, 6. The turning vanes 220 can be configured for minimizing pressure losses in turning the flow through the internal fluid passageway 270.

In this example, the vanes 220 also support the centerbody 280 within the internal fluid passageway 270. Two vanes 220 are provided, symmetrically disposed about the plane PL, each joined to the centerbody 280 at a location generally corresponding to axis B, and to the duct wall 249, and thus the two vanes can be regarded as a single vane traversing the centerbody 280. The vanes 220 in this example are of constant cross-section extending in the lateral direction orthogonal to plane PL, having a leading edge 222 aft of the inlet edge 212, an aft curved portion 224, and a trailing edge 226, as best seen in Fig. 4. In alternative variations of this example, alternative turning vane geometries and/or different number of vanes can be provided. For minimizing pressure loss in the elbow duct 240 due to flow turning by the vanes 220, the vanes 220 are spaced between the outer turning curved wall portion 241 and the inner curved wall portion 243 at corresponding spacings that are generally proportional to the curvature of the vanes 220. For example, and referring to plane PL, the vane position of vanes 220 places the vanes 220 closer to the inner curved wall portion 243 than to the outer turning curved wall portion 241: furthermore, the more curvature the vanes 220 are provided with (for greater turning), the closer the vanes 220 are to inner turning curved wall portion 243. However, in alternative variations of this example, the vanes 220 can be positioned equidistant between the outer turning curved wall portion 241 and the inner curved wall portion 243, for example.

Similarly, in alternative variations of this example in which a cascade of vanes is provided in the elbow duct 240 the spacing between such vanes (as observed on plane PL, for example) can increase with vane position away from the inner curved wall portion 243. Alternatively, in other alternative variations of this example in which a cascade of vanes is provided in the elbow duct 240 the spacing between such vanes (as observed on plane PL, for example) is uniform between the inner curved wall portion 243 and the outer turning curved wall portion 241.

In this example, the centerbody 280 and vanes 220 are fixed in position with respect to inlet edge 212, and the system 100 is configured for operating in steering mode at subsonic and/or supersonic forward speeds. However, in alternative variations of this example, the centerbody 280 (either by itself or optionally together with the vanes) is configured for selectively axially moving fore and aft along axis BB to change position with respect to inlet edge 212, thereby changing the size of the inlet area AI, and the system 100 is configured for operating in steering mode at a wide range of variable supersonic forward speeds, and can thereby enable extending flight range.

In alternative variations of this example, the centerbody 280 can be omitted, and/or the turning vanes 220 can be omitted. In alternative variations of this example, in which the centerbody 280 is retained but the turning vanes 220 are omitted, the centerbody 280 is supported within the passageway 270 in an appropriate manner, for example using radial struts or by extending the centerbody aft towards and affixing to the duct wall 249, though one or both can increase the pressure loss in the elbow duct 249. In yet other alternative variations of this example, in which the centerbody 280 is retained but the turning vanes 220 are omitted, the centerbody 280 can be positioned abutting the duct wall 249 (for example the centerbody 280 forms part of the inner curved wall portion 243), which can allow for greater turning in the elbow duct 240.

In this example, the ratio R between the inlet area AI and the outlet area AO is 1.1, but can instead be, for example, any value in the range 1.1 to 1.5, for example any one of: 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5. In alternative variations of this example, ratio R can be any value in the range 1.1 to 3 or higher, for example. Without being bound to theory, the inventors consider that increasing the value of ratio R greater than about 1.1 reduces the inlet Mach number at the ram inlet 210 and the flow turning pressure loss, but increases the internal volume of internal passageway 270.

In this example, the ratio K between the inlet area AI and the cross-sectional area AC of the steering system 100 is about 0.28, but can instead be, for example, any value in the range 0.1 to 0.5, for example any one of: 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5. In alternative variations of this example, ratio K can be for example any value in the range 0.05 to 0.7, for example any one of: 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7.

During operation of the system 100 in steering mode for steering the body 10 while travelling through the fluid medium M, fluid from the fluid medium M, in this example air, is continuously passed through the internal fluid passageway 270 of the fluid deflector apparatus 200 as a result of the relative forward motion of the steering system 100 with respect to the fluid medium, M. Thus, in this example ram fluid medium (i.e., ram air from the atmosphere) enters the internal fluid passageway 270 via the ram inlet 210, passing through the elbow 240, and out through the exhaust outlet 230, turning by turning angle Θ to provide a radial thrust vector or at least a thrust vector component VR_T, laterally directed in an outward direction with respect to the longitudinal axis B.

This thrust vector or thrust vector component VR_T is the side thrust ST generated by the system 100 to enable steering of the body 100, as will be further disclosed below.

In this example, the internal fluid passageway 270, including the ram inlet 210, the elbow 240, and the exhaust outlet 230 are always open (and in fluid communication with the fluid medium) during steering mode operation of the system 100, and thus ram air is continuously channeled directly to the exhaust outlet 230 from the ram inlet 210 via the elbow 240 so long as the system 100 is travelling with a forward speed relative to the surrounding medium (in this example, air).

Nevertheless, in alternative variations of this example, a closure mechanism can be provided for selectively reducing the size of inlet area AI and/or for selectively closing the ram inlet 210 and/or for selectively reducing the size of outlet area AO and/or for selectively closing the exhaust outlet 230. For example such a feature can be useful when the system 100 is not operating in steering mode, and/or when the system 100 is in the initial phases of the flight path where it can be of particular advantage to minimize drag, and/or where it can be of particular advantage to minimize or controllably change the magnitude of the side thrust. The fluid deflector apparatus 200 further comprises an aft portion 250 defining a volume 252 enclosed by an aft-projecting portion of casing 290.

The mounting arrangement 400 is configured for rotatably mounting the fluid deflector apparatus 200 with respect to the body 10 about the longitudinal axis B. In particular, the mounting arrangement 400 allows the fluid deflector apparatus 200 to freely rotate about axis B (and thus also axis A when co-axial), as controlled via control system 600. Mounting arrangement 400 in this example comprises a forward bearing 420a and an aft bearing 420b coaxial therewith, and a support structure 430 having respective bearing seats 431a and 431b. The bearings 420a, 420b are each mounted to their respective bearing seat 431a, 431b to align the rotational axis of the bearings 420a, 420b with axis B of the fluid deflector apparatus 200. The support structure 430 is fixedly connected to the fluid deflector apparatus 200, for example at casing 290.

In this example, the inner race of each bearing 420a, 420b is fixedly connected to the support structure 430, and the respective outer races are configured for being slidably mounted to body 10, in particular such that the rotational axis of the bearings 420a, 420b are generally aligned with axis A, thereby bringing axis A and axis B into the aforementioned general co-axial alignment. The outer races of bearing 420a, 420b are mounted to body 10 via respective springs 441a, 441b, for limited relative sliding movement with respect to the body 10. The springs 441a, 441b are, for example, in the form of Belleville washers or other coned disc springs, or other types of springs such as for example wave springs etc.

Under steady state conditions, the springs 441a, 441b, act to axially separate the steering system 100 from the body 10 by spacing s such as to allow relative rotation between the steering system 100 and the body 10. For example, such steady state conditions can include parts of the trajectory of the body 10 in which the steering system 100 and body 10 are not subjected to accelerations or where such accelerations are less than a threshold value that would cause the springs 441a, 441b to be compressed axially by a distance less than and up to s, whereas the actual maximum allowable compression of the springs 441a, 441b with respect to the support structure 430 is t. Distance s is the spacing between facing interface surfaces 107 and 17 of the steering system 100 and the body 10, respectively. Thus, when the steering system 100 and the body 10 are subjected to high acceleration loads greater than the aforesaid threshold value (e.g., when launched from a cannon barrel), the steering system 100 is caused to axially displace towards the body 10, and such displacement reaches a maximum at s=0 when the facing interface surface 107 abuts against facing interface surface 17. Since spacing s is less than spacing t, the springs 441a, 441b are not fully compressed and are thus protected from acceleration damage. For example, the springs 441a, 441b are pre-stressed in the installed position shown in Fig. 3 so that under acceleration conditions below the threshold value, spacing s is maintained, while increasing acceleration beyond the threshold value compresses the springs 441a, 441b causing the interface surface 107 to abut against facing interface surface 17, and thus limiting the compression to s.

In this example, the facing interface surfaces 107 and 17 are frustoconical and complementarily shaped. However, in other alternative variations of this example the facing interface surfaces 107 and 17 can have any other suitable form

In alternative variations of this example, the outer races of the bearings 420a, 420b are fixedly connected to the support structure 430, and the respective inner races are configured for being slidably mounted to body 10, in particular such that the rotational axis of the bearings 420a, 420b are aligned with axis A, thereby bringing axis A and axis B into co-axial alignment. In alternative variations of these examples, the mounting arrangement 400 comprises a single bearing, for example bearing 420a or bearing 420b, or the mounting arrangement 400 comprises more than two bearings; in any case the support structure is suitably configured for the respective number of bearings. Either way, in at least some alternative variations of these examples it is not necessary for axis A and axis B to be coaxial alignment, and thus the rotational axis of each bearing 420a, 420b is not aligned with axis A.

The control system 600 is configured for providing and maintaining a desired angular disposition of the fluid deflector apparatus 200 about the longitudinal axis B. This angular disposition is a roll angle γ of the fluid deflector apparatus 200 about axis B, and is independent of the angular orientation of the body 10 with respect to axis A (or indeed with respect to axis B). In other words, the control system 600 provides and maintains a desired roll angle γ of the fluid deflector apparatus 200 about the longitudinal axis B with respect to a fixed external coordinate system or object, for example the Earth, irrespective of whether the body 10 is itself spinning about axis A.

In this example, control system 600 comprises a single control vane 650, located at or in the vicinity of the exhaust outlet 230. For example, the control vane 650, located slightly upstream or slightly downstream of the exhaust outlet 230, for example within a chord length of the control vane 650 upstream or downstream of the exhaust outlet 230. Control vane 650 is pivotable about a vane axis VA (also referred to interchangeably herein as a pivot axis), which is generally parallel to axis B, and offset inwardly from the outlet edge 232 so that most of, or all of, the vane 650 is inside the internal fluid passageway 270 though close to the outlet edge 232. For example, vane axis VA can be considered to be generally parallel to (or generally co-axial with) longitudinal axis B, while actually being angularly displaced by a small angular displacement with respect to longitudinal axis B (as defined on any plane on which lie longitudinal axis B and vane axis VA) from 0° up to ±10°, or preferably from 0° up to ±9°, or preferably from 0° up to ±8°, or preferably from 0° up to ±7°, or preferably from 0° up to ±6°, or preferably from 0° up to ±5°, or preferably from 0° up to ±4°, or preferably from 0° up to ±3°, or preferably from 0° up to ±2°, or preferably from 0° up to ±1°, or preferably from 0° up to ±0.5°. For example, such angular displacements can include typical variations and/or variations to these numerical values.

Referring to Fig. 7, control vane 650 is controllably pivotable about a vane axis VA to provide a controllably variable vane deflection angle φ for the control vane 650 about vane axis VA. Thus, vane deflection angle φ represents the tilt of the vane 650 with respect to plane PA. In this example, the vane 650 has zero camber, and tapers from the forward end 652 to the aft end 654, providing a trapezoidal plan shape with plan area VS. However, in alternative variations of this example, the vane can have any desired camber and/or taper and/or plan shape. In this example, the vane axis VA lies on plane PL.

In alternative variations of this example, the vane axis VA is at an angle to the axis B (for example at 2°, or between 2° and 5°, and/or between 5° and 10°, and/or between 10° and 20°), and/or the vane axis VA is on a plane parallel to plane PL but spaced therefrom. The control system 600 thus has a single control variable, the vane deflection angle φ, which can be controllably varied from a datum position (also referred to interchangeably herein as a "mid-angle" and/or as a datum vane deflection angle), such as for example 0°, to any desired maximum deflection in a clockwise, for example up to +90° (or up to any one of : 10°, or 15°, or 20°, or 25°, or 30°, or 35°, or 40°, or 45°, or 50°, or 55°, or 60°, or 65°, or 70°, or 75°, or 80°, or 85°), or to any desired minimum deflection (i.e., in the anticlockwise direction), for example up to -90° (or up to any one of: -10°, or -15°, or -20°, or -25°, or - 30°, or -35°, or -40°, or -45°, or -50°, or -55°, or -60°, or -65°, or -70°, or -75°, or -80°, or - 85°). At a nominal vane deflection angle 0°, the control vane 650 is aligned with plane PA and presents a minimum cross-sectional profile to the flow through passageway 270. At a vane deflection angle of +90° or -90°, the control vane 650 is orthogonal to plane PA and presents a maximum cross-sectional profile to the flow through passageway 270. However, the ratio Q of the plan area VS of the control vane 650 to the outlet area AO is less than 1.0, and has a value typically between 0.1 and 0.9. For example, the ratio Q can have any one of the following values: 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75,

0.8, 0.85, 0.9. Thus, even at a full vane deflection angle φ of ±90°, the vane 650 does not block the flow of air through the passageway 270. In this example, the inverse of ratio Q,

1. e., ratio Q' between the outlet area AO and the plan area VS is 3.7, but can instead be any value in the range 1.1 to 10 or greater, for example. In alternative variations of this example, ratio Q can be any value in the range 1.1 to 50, for example. The value for ratio Q or ratio Q' can be chosen taking one or more factors into account, for example the desired control bandwidth (i.e., the speed of the dynamic response), the bearing friction of the baring(s) (for example bearings 420a, 420b in this example) and the upstream location of the control vane 650 relative to the exhaust outlet 230.

Referring again to Fig. 7, when vane 650 is pivoted at a vane deflection angle φ greater than 0° and less than 90°, part of the flow that exits the exhaust outlet 230 is deflected in a tangential direction, thereby generating an aerodynamically induced tangential force F on the vane 650 resulting from the lift and drag forces developed on the vane 650. This tangential force F, coupled with the moment arm j between the vane axis VA and axis B, induces a corresponding controllable roll moment N on the fluid deflector apparatus 200 about the longitudinal axis B, which enables the roll angle γ of the fluid deflector apparatus 200 about axis B to be set. Furthermore, the desired angle γ can be maintained relative to the Earth, independently of the rotation of body 10 about its axis A (if there is such rotation) on account of the free bearings 420a, 420b. Bearings 420a, 420b effectively decouple any rotation of the body 10 about axis B from the system 100, and in particular from the fluid deflector apparatus 200.

It is to be noted that while deflection of the vane 650 generates a desired roll moment N, most of the flow through the internal fluid passageway 270 still exits the exhaust outlet 230 in direction T to provide the desired side thrust ST.

Referring to Fig. 3, control vane 650 is pivoted about vane axis VA by actuator 660, which in this example is housed in a molded fairing 291 at the front of the casing 290 and offset from the centerbody 280. In alternative variations of this example, the actuator can be housed elsewhere, for example in the centerbody 280 and operatively connected to the vane 650 by gears, belts, etc, or in the aft portion 250.

Control system 600 further comprises controller 670, housed for example in aft portion 250 and powered by battery 610. Controller 670 controls operation of the control vane 650, to provide a side thrust ST at the desired roll angle γ of the fluid deflector apparatus 200 with respect to the Earth or other external coordinate system For example, controller 670 includes a GPS module or other sensors for determining the position and/or orientation of the system 200 (and thus body 10), and is connected to a computer device or system to determine whether this position is within the desired trajectory of the body 10, and to correct deviations from the trajectory by appropriately steering the body 10 via the application of side force ST where required. Thus the controller 670 can be configured as a closed loop control system. Alternatively, the controller can be configured as an open loop system, to provide side thrust ST to the body 10 at specific points in time after initiation of flight of the body 10 for example, and at directions corresponding to predetermined roll angles γ. In alternative variations of this example, the controller 670 is an analog electronic controller, for example.

Thus, in use, when it is desired to apply a side thrust ST in a particular radial direction with respect to axis B (and thus axis A), the vane 650 is pivoted by a desired deflection angle φ in the positive or negative direction, which induces a roll moment N (correspondingly clockwise or anticlockwise) of the fluid deflector apparatus 200 about the longitudinal axis B. When the desired roll angle γ is achieved, such that the direction of the side thrust ST is now aligned with a desired direction, the vane 650 is pivoted back to a deflection angle cpl that is close to the nominal position of zero deflection angle φ. By setting the deflection angle cpl at a small value close to zero, a relatively small tangential force and corresponding roll moment is maintained sufficient to just balance the frictional moments on the bearings generated as a result of the spin of body 10 - in such case, deflection angle φ 1 becomes the datum deflection angle. The fluid deflector apparatus 200 stops rotating about the longitudinal axis B and thus the desired roll angle γ is maintained at this position for as long as it is desired to apply the side force ST at this desired direction, whether or not the body 10 is spinning. If necessary the vane 650 can be cycled through small positive and negative deflection angles φ (with respect to deflection angle cpl) to maintain the desired roll angle γ (taking into consideration the frictional forces and moments developed by the bearing on account of the spin of body 10). Optionally, a braking system (not shown) can optionally be provided for selectively braking relative rotation of the fluid deflector apparatus 200 about the axis B.

In alternative variations of this example, in which there is little or no spin of the body 10 (for example the body 10 is fin-stabilized), when the desired roll angle γ is achieved, such that the direction of the side thrust ST is now aligned with a desired direction, the vane 650 is pivoted back to the nominal position of zero deflection angle φ. The fluid deflector apparatus 200 stops rotating about the longitudinal axis B and thus the desired roll angle γ is maintained at this position for as long as it is desired to apply the side force ST at this desired direction. If necessary the vane 650 can be cycled through small positive and negative deflection angles φ to maintain the desired roll angle γ.

When it is desired to terminate application of the directed side force ST so that a zero net side force is generated on the body 10 by system 100, the vane 650 is pivoted by a desired deflection angle φ in the positive or negative direction and kept at this angle, which induces a continuous roll moment (correspondingly clockwise or anticlockwise) of the fluid deflector apparatus 200 about the longitudinal axis B. As a result, while the side force ST continues to be applied to the body 10, the direction of the side force is constantly and uniformly changing with respect to its angular disposition about axis B, providing a constant rotational speed, which in turn provides a helical but stable path for the body 10. The axis of the helical path is thus aligned with the nominal or desired trajectory of the body 10. Thus, integration of the side force along each full revolution of the fluid deflector apparatus 200 about axis B results in a zero net side force.

By having a single flow path along the internal fluid passageway 270 from the ram inlet 210 to the exhaust outlet 230, and in particular by providing the exhaust outlet 230 at a single angular position with respect to the axis B, all of the air or fluid entering the ram inlet 210 can be used to generate the side thrust ST and the tangential force F, Fig. 6(a). This enables maximizing the available thrust in the radial and tangential directions with respect to axis B. This also provides a large thrust to weight ratio for the steering system 100, and provides for generation of strong roll moments for rapidly changing the direction of the side thrust with respect to the body 10.

Furthermore, and as has already been mentioned, the internal fluid passageway 270, including the ram inlet 210, the elbow 240, and the exhaust outlet 230, are always open during steering mode operation of the system 100, and thus ram air is continuously channeled directly to the exhaust outlet 230 from the ram inlet 210 via the elbow 240 so long as the system 100 is travelling with a forward speed relative to the surrounding medium (in this example, air). This allows for rapid dynamic response of the steering system to change the roll orientation of the fluid deflector apparatus 200 about the longitudinal axis B rapidly, and to quickly maintain the fluid deflector apparatus 200 at a desired roll orientation, thereby enabling a side thrust as a desired direction to be applied to the steering system 100, and thus to the body 10.

While in this example, control system 600 comprises a single control vane 650, in alternative variations of this example the single control vane can be replaced with a plurality of vanes, for example similar to vane 650 but of smaller plan area to provide a similar effect. In yet other alternative variations of this example the control system 600 alternatively or additionally comprises a mechanical rotation system, for example a motor, for example a stepper motor, for selectively rotating the fluid deflector apparatus 200 about the longitudinal axis B independently of the flow of fluid/air through the internal fluid passageway 270.

In yet other alternative variations of this example the control system 600 alternatively or additionally comprises a jet reaction rotation system, for selectively rotating the fluid deflector apparatus 200 about the longitudinal axis B. for example, one or more reaction jets can be provided in the fluid deflector apparatus 200 having respective fluid exhaust nozzles pointing in the tangential direction and spaced from axis B so that fluid flowing out of the nozzles induces a tangential force on the fluid deflector apparatus 200 and an accompanying roll moment, similar to that produced when deflecting vane 650. For example, operation of such a jet reaction rotation system can be independent of the flow of fluid/air through the internal fluid passageway 270, and the jet reaction rotation system operates using pressurized fluid such as for example helium, nitrogen etc, which can be provided in pressurized tanks and carried by the system 100, for example. Alternatively, operation of such a jet reaction rotation system can be linked to the flow of fluid/air through the internal fluid passageway 270, and for example some of this flowing fluid can be selectively diverted via suitable conduits from the internal fluid passageway 270 to the nozzles. Alternatively, an auxiliary ram inlet is provided (separate from ram inlet 210 and independent of the internal flow passageway 270), and this is in fluid communication with the nozzles, for example via suitable conduits, enabling some additional ram air to be selectively diverted to the nozzles to provide the desired tangential force and corresponding roll moment. Control of operation of these alternative variations of the control system 600 is similar to that disclosed for control system 600, mutatis mutandis. A feature of at least one of these alternative variations of the control system 600 is that such a jet reaction rotation system can avoid pressure losses due to having one or more vanes at or near the exhaust outlet 230 as compared with control system 600.

In yet other alternative variations of this example the control system 600 alternatively or additionally comprises an external aerodynamic control surface arrangement, for example one or more fins, pivotable mounted to an outside of the fluid deflector apparatus 200, and controllably pivotable so that an external flow of the fluid medium (in this case air) over the fluid deflector apparatus 200 and thus with respect to these fins can be partially diverted by the fins when suitably pivoted. This generates an aerodynamic force on these fins, which in turn induces a roll moment to the fluid deflector apparatus 200.

In this example battery 610 provides electrical power to the steering system 100. However, in alternative variations of this example, electrical power can be provided additionally to or instead of the battery, via one or more of: solar cells or a wind turbine. Such a wind turbine can be provided, for example, within the internal fluid passageway 270, or at the nose 281.

In yet other alternative variations of this example, electrical power can be provided additionally or alternatively by exploiting the relative rotation between the body 10 (this being spin stabilized) and steering system 100, for example by providing a suitable dynamo or alternator that is driven by the aforesaid relative rotation. Such a feature can optionally be further enhanced by increasing this relative rotation, for example by providing tilted fins on the fluid deflector apparatus 200 and/or by providing the center of the exhaust outlet 230 offset with the plane PL such that the side force generated by the steering system 100 always has a tangential component for rotating the fluid deflector apparatus 200.

While in this example, the internal fluid passageway 270 comprises a single passageway, extending from a single ram inlet 210 to a single exhaust outlet 230 via elbow 240, in alternative variations of this example other configurations can be provided for the internal fluid passageway 270. For example, ram inlet 210 can be replaced with a plurality of ram inlets and the internal fluid passageway connects the plurality of ram inlets with the single exhaust outlet via suitable ducting, for example bifurcated ducting in the case of two ram inlets. Alternatively, for example, exhaust outlet 230 can be replaced with a plurality of exhaust outlets, and the internal fluid passageway connects the plurality of exhaust outlets with the single ram inlet via suitable ducting, for example bifurcated ducting in the case of two exhaust outlets. Alternatively, for example, exhaust outlet 230 can be replaced with a plurality of exhaust outlets, and the ram inlet 210 can be replaced with a plurality of ram inlets, and the internal fluid passageway connects the plurality of exhaust outlets with the plurality of ram inlets via a common ducting. Alternatively, for example, the internal fluid passageway is formed as a plurality of independent or connected passageways, the exhaust outlet 230 can be replaced with a plurality of exhaust outlets, and the ram inlet 210 can be replaced with a plurality of ram inlets; each of the passageways connects one or more of the exhaust outlets with one or more of the ram inlets via suitable ducting. In any case, even in examples where there is a plurality of exhaust outlets, these are configured to provide a net side force corresponding to side force ST.

In this example, and referring to Fig. 8, the body 10 is designed to incorporate the steering system 100 therein. However, in alternative variations of this example, the respective steering system can be configured for retrofitting to existing bodies 10, for example existing projectiles.

For example, and referring to Fig. 9, body 10 is in the form of a projectile or missile 10A, having an aerodynamically contoured nose portion in the form of conical nose 11 A, cylindrical body 12A and tail (not shown). In this example, the respective steering system 100A is similar to steering system 100, mutatis mutandis, with some differences. For example, the bearing 420A (corresponding to one or both of bearings 420a, 420b of steering system 100) is rotatably mounted to the missile 10A via interface 19A to allow the respective fluid deflector apparatus 200A to rotate freely about the longitudinal axis B, and thus decouple the fluid deflector apparatus 200A from the missile 10A in roll. Interface 19A comprises a cylindrical fairing that fits onto the nose 11A, thereby appearing to effectively extend the cylindrical body 12A forward. The aft end of interface 19A abuts the external casing of the missile 10A, while the forward end of interface 19A is configured to engage with one of the inner or outer races of bearing 420A, while the fluid deflector apparatus 200A is engaged to the other one of the inner or outer races of bearing 420A. As can be seen, the bearing 420A is sized to allow part of the nose 11A to project therethrough and into the respective volume 252A of aft portion 250A, the volume 252A being enclosed by an aft-projecting portion of casing 290A. Further, it can be noted that while in the specific design of steering system 100A illustrated in Fig. 9, no centerbody is provided, the vane actuator is accommodated in volume 252A and the vane 650A is not tapered, in fact the steering system 100A can comprise all the elements and features as disclosed herein for the first example of steering system 100, or alternative variations thereof, mutatis mutandis. In alternative variations of the above examples, particularly where the respective body has zero or very low spin rate, the steering system can be incorporated in a pod, which in turn is mounted to a wing or fuselage of an air vehicle, and/or one or more steering systems can be integrated in the wings and/or fuselage. Such steering systems can be used for providing steering forces to the air vehicle in addition to, or instead of, aerodynamic steering forces generated by aerodynamic surfaces of the air vehicle (if any), such as for example ailerons, rudders etc.

In the method claims that follow, alphanumeric characters and Roman numerals used to designate claim steps are provided for convenience only and do not imply any particular order of performing the steps.

Finally, it should be noted that the word "comprising" as used throughout the appended claims is to be interpreted to mean "including but not limited to".

While there has been shown and disclosed examples in accordance with the presently disclosed subject matter, it will be appreciated that many changes can be made therein without departing from the spirit of the presently disclosed subject matter.

Claims

CLAIMS:

1. A steering system for a body configured for moving through a fluid medium, the steering system having a longitudinal axis and comprising: fluid deflector apparatus defining at least a part of an external casing of the steering system, and including a ram inlet, an exhaust outlet defined on said external casing and laterally disposed with respect to the longitudinal axis, and an internal fluid passageway extending between said ram inlet and said exhaust outlet, wherein said internal fluid passageway is immovably positioned with respect to at least said exhaust outlet; mounting arrangement configured for rotatably mounting the fluid deflector apparatus with respect to the body about the longitudinal axis; and control system configured for selectively providing and maintaining a desired angular disposition of the fluid deflector about the longitudinal axis.

2. The steering system according to claim 1 , wherein said internal fluid passageway is immovably positioned with respect to said ram inlet.

3. The steering system according to claim 1 or claim 2, wherein said internal fluid passageway has a fixed spatial disposition with respect to at least the exhaust outlet at least during steering mode operation of the steering system wherein fluid from the fluid medium is passing through said internal fluid passageway.

4. The steering system according to any one of claims 1 to 3, wherein said internal fluid passageway has a fixed spatial disposition with respect to the ram inlet.

5. The steering system according to any one of claims 1 to 4, wherein the exhaust outlet is in permanent fluid communication with the ram inlet via said internal fluid passageway.

6. The steering system according to any one of claims 1 to 5, wherein said exhaust outlet is permanently open to the fluid medium at least when the steering system is travelling through the fluid medium.

7. The steering system according to any one of claims 1 to 6, wherein in operation of the steering system in said steering mode to provide selective lateral steering control to the body, fluid from said fluid medium is continuously channeled through said fluid deflector apparatus from said ram inlet to said exhaust outlet and out of said exhaust outlet via a fixed fluid path defined by said internal fluid passageway.

8. The steering system according to any one of claims 1 to 7, wherein responsive to the steering system moving through the fluid medium, fluid from said fluid medium is continuously channeled through said fluid deflector apparatus from said ram inlet to said exhaust outlet and out of said exhaust outlet via a fixed fluid path defined by said internal fluid passageway.

9. The steering system according to any one of claims 1 to 8, wherein responsive to said steering system moving through the fluid medium, fluid from said fluid medium is continuously channeled through said fluid deflector apparatus to continuously generate a side force.

10. The steering system according to any one of claims 1 to 9, wherein said control system is configured for selectively providing a continuous uniform rotation of the fluid deflector apparatus about the longitudinal axis while said steering system is moving through the fluid medium, the fluid from said medium being continuously channeled through said fluid deflector apparatus to generate a zero net side force integrated over each full revolution of the fluid deflector apparatus about said longitudinal axis.

11. The steering system according to any one of claims 1 to 10, wherein said internal fluid passageway is configured for turning the flow from a generally axial direction to a generally lateral direction by a flow turning angle.

12. The steering system according to claim 11 , where said flow turning angle is about 90°.

13. The steering system according to any one of claims 1 to 12, wherein said internal fluid passageway comprises an elbow duct.

14. The steering system according to any one of claims 1 to 13, wherein said internal fluid passageway comprises a plurality of fluid turning vanes for facilitating turning the flow through said internal fluid passageway.

15. The steering system according to any one of claims 1 to 14, comprising a centerbody provided in said internal fluid passageway in proximity to said ram inlet.

16. The steering system according to claim 15, wherein said centerbody is in fixed spatial relationship with respect to said ram inlet.

17. The steering system according to any one of claims 15 to 16, wherein said centerbody is immovably connected to said internal fluid passageway.

18. The steering system according to any one of claims 15 to 16, wherein said centerbody is movably connected to said internal fluid passageway

19. The steering system according to claim 18, wherein said centerbody is axially movable with respect to said ram inlet.

20. The steering system according to any one of claims 1 to 19, wherein a first ratio between an inlet area associated with said ram inlet and an outlet area associated with said exhaust outlet is 1.1.

21. The steering system according to any one of claims 1 to 19, wherein a first ratio between an inlet area associated with said ram inlet and an outlet area associated with said exhaust outlet is in a range 1.1 to 3.

22. The steering system according to any one of claims 1 to 21, wherein said mounting arrangement comprises a bearing structure for mounting the steering system to the body thereby.

23. The steering system according to any one of claims 1 to 22, wherein said mounting arrangement is configured for allowing free pivoting of said steering system with respect to the body when mounted thereto.

24. The steering system according to any one of claims 1 to 23, wherein said mounting arrangement is configured for providing decoupling rotation of said steering system about said longitudinal axis with respect to the body when mounted thereto.

25. The steering system according to any one of claims 1 to 24, wherein said mounting arrangement is configured for enabling the steering system to be retrofittably mounted to the body, the body being in the form of a projectile.

26. The steering system according to any one of claims 1 to 25, wherein said mounting arrangement is configured for enabling the steering system to be retrofittably mounted to the body, the body having an aerodynamically contoured nose portion.

27. The steering system according to any one of claims 1 to 26, wherein the control system comprises at least one control vane pivotably mounted at said exhaust outlet.

28. The steering system according to claim 27, wherein said at least one control vane is pivotable about a pivot axis about a vane deflection angle.

29. The steering system according to clam 28, wherein said pivot axis is generally parallel to said longitudinal axis.

30. The steering system according to any one of claims 27 to 29, wherein said at least one control vane is pivotable between a datum said vane deflection angle and at least one of a maximum said vane deflection angle or a minimum said vane deflection angle.

31. The steering system according to claim 30, wherein at said datum vane deflection angle, said at least one control vane presents a minimum cross-section to fluid flow passing through said internal fluid passageway.

32. The steering system according to claim 30, wherein at said datum vane deflection angle, said at least one control vane provides a tangential force and corresponding roll moment to the steering system complementary to a frictional moment that can be generated resulting from a relative rotation between the steering system and the body.

33. The steering system according to any one of claims 30 to 31, wherein the control system is configured to operate such that at said datum vane deflection angle, said at least one control vane is prevented from tangentially diverting fluid flow passing out of said exhaust outlet.

34. The steering system according to any one of claims 28 to 32, wherein at a respective said vane deflection angle greater or smaller than said datum vane deflection angle, said at least one control vane tangentially diverts fluid flow passing out of said exhaust outlet to generate a correspondingly positive or negative roll moment and to thereby provide said desired angular disposition of the fluid deflector about the longitudinal axis.

35. The steering system according to any one of claims 28 to 34, wherein the control system is configured for providing a respective said vane deflection angle greater or smaller than said datum vane deflection angle, wherein said at least one control vane tangentially diverts fluid flow passing out of said exhaust outlet to generate a correspondingly positive or negative roll moment to thereby provide said desired angular disposition of the fluid deflector about the longitudinal axis, and wherein the control system is further configured for subsequently providing a respective said vane deflection angle equal to said datum vane deflection angle to selectively maintain said desired angular disposition.

36. The steering system according to any one of claims 30 to 35, wherein at said maximum vane deflection angle, said at least one control vane presents a maximum cross-section to fluid flow passing through said internal fluid passageway.

37. The steering system according to any one of claims 27 to 36, wherein a ratio of the outlet area associated with the exhaust outlet to a plan area of the at least one control vane is greater than 1.0.

38. The steering system according to any one of claims 27 to 36, wherein a ratio of a plan area of the at least one control vane to the outlet area associated with the exhaust outlet is in the range 0.1 to 0.9.

39. The steering system according to any one of claims 1 to 38, wherein said fluid medium is air.

40. The steering system according to any one of claims 1 to 39, wherein the body is a projectile or other air vehicle.

41. The steering system according to any one of claims 1 to 38, wherein the fluid medium is water

42. The steering system according to any one of claims 1 to 38 or 41, wherein the body is a torpedo or other water craft.

43. A vehicle comprising a body and a steering system mounted to the body, the steering system being as defined in any one of claims 1 to 42.

44. The vehicle according to claim 43, wherein the body is elongate having a body longitudinal axis, and wherein said longitudinal axis of said steering system is co-axial with said body longitudinal axis.

45. A method for steering for a body moving through a fluid medium, comprising :

(a) providing a steering system as defined in any one of claims 1 to 42, and