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GB2258575A - Re-entry vehicle guidance system - Google Patents

Re-entry vehicle guidance system Download PDF

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Publication number
GB2258575A
GB2258575A GB8516044A GB8516044A GB2258575A GB 2258575 A GB2258575 A GB 2258575A GB 8516044 A GB8516044 A GB 8516044A GB 8516044 A GB8516044 A GB 8516044A GB 2258575 A GB2258575 A GB 2258575A
Authority
GB
United Kingdom
Prior art keywords
reflector
vehicle
radar
entry
earth
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8516044A
Other versions
GB8516044D0 (en
GB2258575B (en
Inventor
Ashley Kenneth Blake
Colin Frederick Rogers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BAE Systems PLC
Original Assignee
British Aerospace PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by British Aerospace PLC filed Critical British Aerospace PLC
Publication of GB8516044D0 publication Critical patent/GB8516044D0/en
Publication of GB2258575A publication Critical patent/GB2258575A/en
Application granted granted Critical
Publication of GB2258575B publication Critical patent/GB2258575B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/88Radar or analogous systems specially adapted for specific applications
    • G01S13/89Radar or analogous systems specially adapted for specific applications for mapping or imaging
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01SRADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/66Radar-tracking systems; Analogous systems
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00Details of, or arrangements associated with, antennas
    • H01Q1/27Adaptation for use in or on movable bodies
    • H01Q1/28Adaptation for use in or on aircraft, missiles, satellites, or balloons
    • H01Q1/281Nose antennas
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/12Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems
    • H01Q3/16Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying relative position of primary active element and a reflecting device
    • H01Q3/20Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical relative movement between primary active elements and secondary devices of antennas or antenna systems for varying relative position of primary active element and a reflecting device wherein the primary active element is fixed and the reflecting device is movable

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  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Electromagnetism (AREA)
  • Astronomy & Astrophysics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

A re-entry vehicle 1 which is arranged to approach the earth's surface 3 with its longitudinal centre line X-X at a given approach angle 4 or range of angles and which requires to be guided toward a target area, includes a radar guidance system which directs a beam 5 generally obliquely away from the longitudinal centre line X-X of the vehicle toward the ground 3, the return being received by the radar system and compared with pre-stored reference scenes so that positional errors can be determined for terminally guiding the vehicle. The radar guidance system includes a pivotal reflector (e.g. 8, Figs 2, 3 not shown) housed within a slender body region 2 of the vehicle 1, the reflector having a major dimension (8a) greater than the local width of the body region 2. <IMAGE>

Description

GUIDANCE SYSTEM AND METHOD This invention relates to radar guidance systems for re-entry vehicles, that is to say vehicles that re-enter the earth's atmosphere from space, and to methods of operation.
It is known from "Flight International" dated 8th August, 1981, pages 431 - 434, and from "International Defense Review" 8/1979, pages 1303 - 1308, that a re-entry vehicle can be provided with a radar guidance system in which a beam of doughnut (that is to say) shaped azimuth scanning pattern is projected generally forwardly of the vehicle, the returns from which are compared with pre-stored reference scenes of the target area in a correlator to determine position errors which are then used to effect terminal guidance manoeuvres.
A suitable correlator device is illustrated as described in "Aviation Week and Space Technology", 12th May, 1975, pages 45 - 47.
Such an arrangement encounters severe problems since the re-entry speed, which can be up to M = 8.0, necessitates a slender nose shape for the vehicle; this shape is not conducive to good radar performance in a generally forward direction. An object of the present invention is to provide a guidance system which mitigates this problem.
According to one aspect of the present invention, a re-entry vehicle which is arranged to approach the earth's surface with its longitudinal centre line at a given approach angle or range of angles and which requires to be guided toward a target area, includes a radar guidance system which directs a beam generally obliquely away from the longitudinal centre line of the vehicle toward the ground, the return being received by the radar system and compared with pre-stored reference scenes so that positional errors can be determined for terminally guiding the vehicle.
By this arrangement, the radar system can include an antenna which, because of the chosen direction of its beam, can be readily aocommodated within a slender nose.
Moreover, since the vehicle approaches the ground at a given angle or angles, and the radar beam is arranged to be directed from a side rather than along the axis X - X of the vehicle, it illuminates the ground well forward of the target area; it does not therefore illuminate the target area itself (merely the approach area to it) and is thus unlikely to pick up spurious returns provided by decoys in the target vicinity.
According to a further aspect of the invention, a method of operating the apparatus defined above comprises pre-storing one or more earth scenes of regions of known position with reference to a target, bringing the vehicle into a desired line of approach with respect to the earth's surface, adjusting the radar reflector to direct a beam downwards towards the earth's surface at a desired angle to illuminate those regions to produce scenes which will correlate with the pre-stored scenes, effecting such correlation to obtain positional error information, and subsequently effecting terminal guidance correction of the vehicle.
These, and further aspects of the invention, are described by way of example with reference to the accompanying drawings in which: Figure 1 is a diagram of a re-entry vehicle approaching the earth's surface, Figure 2 is a side view of a nose region of a re-entry vehicle, Figure 3 is a plan view of the antenna of Figure 2, Figure 4 is a cross-section upon line A - A of Figure 3, Figure 5 is a similar view to that of Figure 2, but illustrating an alternative radar system, Figure 6 is a plan view of the antenna of Figure 5, Figure 7 is a perspective view of the embodiment of Figure 2, Figure 8 is a perspective view of the embodiment of Figure 5, and Figure 9 is similar to Figures 2 and 5 but of purely diagrammatic form illustrating a further alternative antenna arrangement.
Referring initially to Figure 1, a re-entry vehicle 1, has a generally cylindrical body, a slender nose cone 2, and a longitudinal axis X - X. It approaches the earth's surface 3 at a fairly shallow angle or range of angles denoted by 4; the axis X - X is generally coincident with the line of approach.
Hitherto, re-entry vehicles have been terminally guided by a radar system which projects a beam generally forward along the axis X - X or near to it. In the present vehicle, the radar system projects a beam 5 generally transversely to the axis X - X so that as the vehicle descends at the approach angle 4 with its axis X - X generally coincident with the line of approach, the beam 5 is directed downwards and rearwards to strike the ground at an angle 6.
Figures 2, 3, 4 and 7 illustrate a radar system arranged to achieve the effect of Figure 1. The radar system is arranged to operate at millimetric frequencies, say 35 G N . It utilizes an off-axis Herschel antenna system including a concave reflector 8 and a feed horn 9 carried thereby protruding through a cutaway region 10 at one edge of the reflector 8. The reflector is pivoted about an axis transverse to the X - X axis by means of a ball joint 8b to lie at an oblique angle or angles to that axis. It thus has a forwarded edge 8f and a trailing edge 8r. It is capable of being tilted to position 8', by twin servo mechanisms 11 and 12, to compensate for variations in the approach angle 4 of the vehicle.For such tilting movement, the twin servo mechanisms, which lie one to each side of the axis X are moved in unison.
The e reflector 8 is also arranged to scan from side-to-side to effect searching about the axis X - X. This is effected by moving the twin servo mechanisms 11 and 12 each in the opposite sense.
An electro-magnetic radiation transparent panel 13 is provided in the surface of the vehicle through which the radar beam 5 and its reflection passes. The vehicle is space stabilised so that to scan a sufficient ground area only a portion of the surface of the vehicle requires to be formed by the panel 13.
Conveniently, that space forward of the reflector 8 is utilized to house microwave generating apparatus 14 and correlation apparatus 15 which would in previous vehicles be required to be housed with less convenience elsewhere.
The panel is set well back from the nose tip of the vehicle; it is thus less susceptible to kinetic heating than in previous arrangements.
An alternative arrangement is illustrated in Figures 5, 6 and 8 in which like copponents are given like reference numerals. This provides a radar system capable of operating as previously described, but provides the effect by an alternative reflector and associated equipment.
A reflector 20 is carried, by means of a hinge 25, for tilting movement through oblique angles about an axis transverse to the longitudinal axis X - X, tilting being effected by a motor 21 which rotates a disc 22 and thereby moves a push-pull rod 23 which is attached both to the disc and to the rear of the reflector. As previously, a feed horn 24 is carried by and moves with the reflector.
To effect scanning to either side of the X - X axis, the hinge 25 is itself carried upon a yoke 26 which is rotatable by means of a motor 27 about the axis X - X. The reflector 20 again has a major dimension 20a greater than the local depth of 2a of the slender nose region in which it is housed since it lies at an oblique angle or angles to the axis X - X, the reflector has a forward edge 20f and a trailing edge 20r.
Yet a further arrangement is shown in Figure 9 in diagrammatic form. Again, like corrponents are given like reference numerals. In this embodiment, a feed horn 30 directs radiation upon a secondary movable reflector 31 and fran there onto a primary reflector 32. An advantage with this embodiment is that double the angular movement of the transmitted beam 5 can be effected for the same degree of tilt of the reflector 32. The reflector 32 has a major dimension 32a greater than the local depth 2a of slender nose region. It lies obliquely to the axis X - X and thus has a forward region 32f and trailing region 32r. The e reflector is mounted at 33.
In use, the guidance system is operated as the vehicle approaches the ground at a known approach angle 4O The reflector 8, 20 or 32 is tilted to direct the transmitted beam 5 at a desired angle to the axis X - X, so that it strikes the ground at a desired angle 6. At a designated position or time a scanning movement of the beam is initiated, rastering being effected by the forward movement of the vehicle. It thus searches for predetermined terrain features, the scenes containing such features having already been stored in the correlator 15. In practice, scenes including sharp delineations of feature will be stored so that such features will therefore be searched for.These include such features as (i) roads (ii) telegraph wires (iii) townships (iv) rivers (v) lakes (vi) edges of snow fields (vii) railways When a general area of terrain has been identified, a detailed search for correlation with a specific edge feature of high delineation is then commenced. On such correlation, the target position can be determined without performing a scan of the target area. There is no necessity to perform a continuous scan of terrain.
Only those regions having terrain features stored in the correlator and over which the vehicle is passing at a given instant require to be scanned.
The apparatus and method have particular use against high value targets which may be defended by ECM and for radar decoy systems.
On the technical side, they have advantage in that the sideways looking technique, together with use of a millimetric high resolution system, at least reduces radome problems.
It is possible to utilize a high gain antenna which provides a small illumination area, and because only small terrain areas are examined (and the target area never) there is an inherent resistance to ECM. This resistance is enhanced by the choice of millimetric frequencies.
As a corollary, it is envisaged that if several re-entry vehicles were used simultaneously, each could examine different terrain areas thereby yet further improving resistance to ECM techniques.

Claims (10)

1. A re-entry vehicle including a body region of elongate slender form having a longitudinal axis, a radar guidance system for guiding the vehicle towards a target area on the earth's surface, the guidance system including reflector means housed within the slender body region for directing a radar beams laterally away from the longitudinal axis, and storage means for storing at least one pre-determined reference scene remote from the target area on the earth's surface below the re-entry path of the vehicle and comparing the radar beam return with that reference scene, whereby during re-entry when the longitudinal axis is at an oblique angle to the earth's surface the radar beam is directed generally towards the pre-determined reference scene such that positional errors can be determined without directing the radar beam to the target area.
2. A re-entry vehicle according to Claim 1, in which the reflector means has a major dimension greater than the local depth of the slender body region within which it is housed, and mounting means provided for mounting the reflector means at an oblique angle to the longitudinal axis such that the reflector thus has a forward edge region and a trailing edge region.
3. A re-entry vehicle according to Claim 2 wherein the mounting means is in the form of a pivot located between said forward edge and trailing edge regions allowing pivotal movement of the reflector means at least about a pitch axis extending laterally of said longitudinal axis.
4. A re-entry vehicle according to Claim 3, wherein the pivot additionally allows pivotal movement of the reflector means about a roll axis on or parallel to said longitudinal axis.
5. A re-entry vehicle according to Claim 2 wherein the mounting means is in the form of a pivot located at the forward edge region of the reflector allowing pivotal movement at least about a pitch axis extending laterally of said longitudinal axis.
6. A re-entry vehicle according to Claim 5, wherein the pivot additionally allows pivotal movement of the reflector means about a roll axis on or parallel to said longitudinal axis.
7. A re-entry vehicle according to Claim 2, wherein the mounting means fixes the reflector means with reference to the body, and an additional reflector means tiltable with respect to the body is provided to direct radiation to or from said reflector means.
8. A re-entry vehicle according to any one of the previous claims wherein the elongate slender body region forms a nose of the vehicle with a leading tip region, the reflector means is mounted aft of the tip region and the storage means is mounted in the tip region forward of the reflector means.
9. A re-entry vehicle which is arranged to approach the earth's surface with its longitudinal centre line at a given approach angle or range of angles and which requires to be guided toward a target area, includes a radar guidance system which directs a beam generally obliquely away from the longitudinal centre line of the vehicle toward the ground, the return being received by the radar system and compared with pre-stored reference scenes so that positional errors can be determined for terminally guiding the vehicle.
10. A method of operating a re-entry vehicle comprising the steps of: disposing a radar reflector in said vehicle so that a major dimension of said reflector is greater than a width of that portion of the vehicle within which the reflector is mounted; pre-storing one or more earth scenes of regions of known position with reference to but spaced from a target; bringing the vehicle into a desired line of approach with respect to the earth's surface; adjusting the radar reflector to direct a beam downwards towards the earth's surface at a desired angle away from said target but so as to illuminate those regions to produce scenes which will correlate with the pre-stored scenes, effecting such correlation to obtain positioned error information; and effecting terminal guidance correction of the vehicle.
10. A method of operating the re-entry vehicle according to any one of the previous claims comprising pre-storing one or more earth scenes of regions of known position with reference to a target, bringing the vehicle into a desired line of approach with respect to the earth's surface, adjusting the radar reflector to direct a beam downwards towards the earth's surface at a desired angle to illuminate those regions to produce scenes which will correlate with the pre-stored scenes, effecting such correlation to obtain positional error information, and subsequently effecting terminal guidance correction of the vehicle.
AMENDIKMS TO THE CLAMS HAVE BEEN FLED AS FOLLOWS 1. A re-entry vehicle comprising: a body region of elongate slender form having a longitudinal axis; a radar guidance system for guiding the vehicle towards a target area on the earth's surface, the guidance system including reflector means housed within the slender body region for directing a radar beam laterally away from the longitudinal axis and away from said target area, said reflector means having a major dimension greater than a local width of the slender body region within which said reflector means is housed; and correlating means for storing at least one pre-determined reference scene remote from the target area on the earth's surface below a re-entry path of the vehicle, and for comparing the radar beam return with said reference scene, to cause, during re-entry when the longitudinal axis is at an oblique angle to the earth's surface, the radar beam to be directed generally towards the pre-determined reference scene and away from said target area so that positional errors can be determined without directing the radar beam at the target area.
2. A re-entry vehicle according to Claim 1, further including mounting means provided for mounting the reflector means at an oblique angle to the longitudinal axis such that the reflector thus has a forward edge region and a trailing edge region.
3. A reentry vehicle according to Claim 2 wherein the mounting means is in the form of a pivot located between said forward edge and trailing edge regions allowing pivotal movement of the reflector means at least about a pitch axis extending laterally of said longitudinal axis.
4. A re-entry vehicle according to Claim 3, wherein the pivot additionally allows pivotal movement of the reflector means about a roll axis on or parallel to said longitudinal axis 5 A re-entry vehicle according to Claim 2 wherein the mounting means is in the form of a pivot located at the forward edge region of the reflector allowing pivotal movement at least about a pitch axis extending laterally of said longitudinal axis.
6. A re-entry vehicle according to claim 5, wherein the pivot includes means for allowing pivotal movement of the reflector means about a roll axis on or parallel to said longitudinal axis.
7. A re-entry vehicle according to Claim 2, wherein the mounting means includes means for fixing the reflector means with reference to the body, and further including an additional reflector means tiltable with respect to the body to direct radiation to or from said reflector means.
8. A re-entry vehicle according to any one of the previous claims wherein the elongate slender bedy region forms a nose of the vehicle with a leading tip region, the reflector means is mounted aft of the tip region and the storage means is mounted in the tip region forward of the reflector means.
9. A re-entry vehicle which is arranged to approach the earth's surface with its longitudinal centre line at a given approach angle or range of angles and which requires to be guided toward a target area, including: a radar guidance system for constantly directing a radar beam generally obliquely away from the longitudinal centre line of the vehicle toward the ground, the return being received by the radar system and compared with pre-stored reference scenes so that positional errors can be determined for terminally guiding the vehicle, said radar system having a reflector with a major dimension greater than a width of the portion of the vehicle within which said reflector is mounted.
GB8516044A 1984-06-29 1985-06-25 Guidance system and method Expired - Fee Related GB2258575B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB848416611A GB8416611D0 (en) 1984-06-29 1984-06-29 Guidance system and method

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GB8516044D0 GB8516044D0 (en) 1992-11-04
GB2258575A true GB2258575A (en) 1993-02-10
GB2258575B GB2258575B (en) 1993-07-14

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GB8516044A Expired - Fee Related GB2258575B (en) 1984-06-29 1985-06-25 Guidance system and method

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103486905A (en) * 2013-09-06 2014-01-01 中国运载火箭技术研究院 Determining method for terminal guidance shift-exchange conditions of reenter vehicle

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110851915B (en) * 2019-10-28 2024-02-23 中国航天空气动力技术研究院 High-speed plane symmetrical aircraft large maneuvering turning energy control method, medium and equipment

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1537157A (en) * 1975-06-24 1978-12-29 Thomson Csf High repetition frequency side-looking pulse radar system
US4144571A (en) * 1977-03-15 1979-03-13 E-Systems, Inc. Vehicle guidance system
US4179693A (en) * 1977-05-23 1979-12-18 Rockwell Internation Corporation Autonomous, check-pointing, navigational system for an airborne vehicle
GB2025723A (en) * 1978-07-14 1980-01-23 Ver Flugtechnische Werke Surface navigation system
GB2060306A (en) * 1979-09-26 1981-04-29 Ver Flugtechnische Werke A surface navigation system for aircraft
GB2072988A (en) * 1980-03-26 1981-10-07 Ver Flugtechnische Werke A surface navigation system for air and/or sea-going craft
GB2111789A (en) * 1981-11-27 1983-07-06 United Technologies Corp Map matcher missile guidance system
GB2116000A (en) * 1982-03-02 1983-09-14 Elliott Bros Guidance system

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1537157A (en) * 1975-06-24 1978-12-29 Thomson Csf High repetition frequency side-looking pulse radar system
US4144571A (en) * 1977-03-15 1979-03-13 E-Systems, Inc. Vehicle guidance system
GB1547739A (en) * 1977-03-15 1979-06-27 E Systems Inc Vehicle guidance system
US4179693A (en) * 1977-05-23 1979-12-18 Rockwell Internation Corporation Autonomous, check-pointing, navigational system for an airborne vehicle
GB2025723A (en) * 1978-07-14 1980-01-23 Ver Flugtechnische Werke Surface navigation system
GB2060306A (en) * 1979-09-26 1981-04-29 Ver Flugtechnische Werke A surface navigation system for aircraft
GB2072988A (en) * 1980-03-26 1981-10-07 Ver Flugtechnische Werke A surface navigation system for air and/or sea-going craft
GB2111789A (en) * 1981-11-27 1983-07-06 United Technologies Corp Map matcher missile guidance system
GB2116000A (en) * 1982-03-02 1983-09-14 Elliott Bros Guidance system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103486905A (en) * 2013-09-06 2014-01-01 中国运载火箭技术研究院 Determining method for terminal guidance shift-exchange conditions of reenter vehicle

Also Published As

Publication number Publication date
GB8416611D0 (en) 1992-11-04
GB8516044D0 (en) 1992-11-04
GB2258575B (en) 1993-07-14

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 19931014