INERTIAL NAVIGATION SYSTEMS
First Claim
1. For an inertial guidance system for aircraft based on a ship, where each aircraft carries a three-axis inertial platform including three single-axis gyros and two linear accelerometers with an associated navigational computer, reference equipment, common to the said aircraft, for location on the ship and including a three-axis reference inertial platform similar to the said inertial platform carried by each aircraft, means for operating the reference equipment so that in operation the platform is maintained in a predetermined horizontal plane and orientated in a predetermined compass direction, pickoff means for deriving signals from the reference platform to represent orthogonal components of the ship'"'"''"'"'s acceleration and velocity at the reference platform, means for converting those derived signals to local resolved values at each aircraft in dependence on the distance and bearing of the aircraft from the reference equipment, and means for applying those local resolved signals to the inertial equipment of the aircraft so as to level its inertial platform prior to take-off.
1 Assignment
0 Petitions
Accused Products
Abstract
Apparatus for quickly levelling and orientating the inertial navigation platforms of shipborne fighter aircraft prior to takeoff including a shipborne reference inertial platform common to all the aircraft and stabilised against the ship'"'"''"'"'s pitch, roll and yaw, together with a computer system for slaving to that reference platform the platform of each aircraft in turn.
12 Citations
8 Claims
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1. For an inertial guidance system for aircraft based on a ship, where each aircraft carries a three-axis inertial platform including three single-axis gyros and two linear accelerometers with an associated navigational computer, reference equipment, common to the said aircraft, for location on the ship and including a three-axis reference inertial platform similar to the said inertial platform carried by each aircraft, means for operating the reference equipment so that in operation the platform is maintained in a predetermined horizontal plane and orientated in a predetermined compass direction, pickoff means for deriving signals from the reference platform to represent orthogonal components of the ship'"'"''"'"'s acceleration and velocity at the reference platform, means for converting those derived signals to local resolved values at each aircraft in dependence on the distance and bearing of the aircraft from the reference equipment, and means for applying those local resolved signals to the inertial equipment of the aircraft so as to level its inertial platform prior to take-off.
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2. Apparatus as claimed in claim 1 where each aircraft possesses means for providing the pilot with a head-up display of an aiming line at infinity, wherein each aircraft is further provided with means operable when the inertial platform of the aircraft is in said plane for comparing the headings of the reference and aircraft platforms and causing the said display to indicate when there is a difference between them, thereby allowing the pilot to correct that difference by precessing the azimuth gimbal of his platform anc so causing the platform to rotate in azimuth.
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3. For an inertial guidance system for aircraft based on a ship, where each aircraft carries a three-axis inertial platform including three single-axis gyros and two linear accelerometers with an associated navigational computer with means for providing the pilot with a head-up display of an aiming line at infinity, reference equipment, common to the said aircraft, for location on the ship and including a three-axis reference inertial platform similar to the said inertial platform carried by each aircraft, means for operating the reference equipment so that in operation the reference platform is maintained in a predetermined horizontal plane and orientated in a predetermined compass direction, a sighting mark to be visible to the pilot of each aircraft through his head-up display where the aircraft is in position for take-off, means for determining the bearing of the sighting mark as viewed from each aircraft and the distance of the aircraft from the reference platform, means for deriving from the accelerometers of the reference platform signals to represent the North-South and East-West components of acceleration and velocity at the reference platform resolved in the said plane, and computing means for deriving from said signals and from the distance and bearing of the aircraft from the reference equipment the local velocity and acceleration components at the aircraft resolved into North-South and East-West directions in a horizontal plane, each aircraft being provided with means for applying those resolved components to level the platform of the aircraft prior to take-off, means operable when the inertial platform of the aircraft is level and the aircraft itself is at least approximately aligned on the sighting mark for causing the head-up display of the aircraft to respond to the difference between the said bearing of the sighting mark as viewed from the aircraft and the heading of the aircraft as derived from the inertial platform of the aircraft so as to cause the aiming line of the display to be in register with the sighting mark when the platform of the aircraft is in alignment in azimuth with the reference platform, and means to allow the pilot to precess the azimuth gimbal of the platform of his aircraft whilst observing said display until such alignment is achieved.
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4. Apparatus as claimed in claim 3 wherein the computing means for deriving the local velocity and acceleration components at the aircraft includes resolvers for deriving from the distance R between the aircraft and the reference platform North-South and East-West signals proportional to Rcos theta cos(180+ phi ) and Ros theta sin(180+ phi ), where theta is the angle of elevation from said horizontal plane of the sight line between the reference equipment and the aircraft and phi is the angle between said predetermined compass direction and said sight line as resolved in that plane, means for deriving the first-order time derivatives of the said North-South and East-West signals and adding them to the said signals which represents the North-South and East-West components of velocity at the reference platform and so produce the corresponding components at the aircraft, and means for deriving the second-order time derivatives of the said North-South and East-West signals and adding them to the said signals which represents the North-South and East-West components of acceleration at the reference platform and so produce the corresponding components at the aircraft.
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5. Apparatus as claimed in claim 3 wherein the reference platform is supported by inner and outer gimbals from a casing which is rotatable about an axis which is normal to the deck of the ship and passes through the point of intersection of the gimbal axes, said means for determining the bearing of the sighting mark including a telescope attached to said casing with the optical axis of the telescope coplanar with the axis of the outer gimbal and the axis of rotation of the casing, whereby a rotation of the casing allows the telescope to be brought to bear on each aircraft in turn.
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6. Apparatus as claimed in claim 4 wherein said telescope also serves as said means for determining the distance of the aircraft from the reference platform.
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7. In an inertial guidance system for aircraft based on a ship, where each aircraft carries a three-axis inertial platform including three single-axis gyros and two linear accelerometers with an associated navigational computer and providing in operation a head-up display of an aiming line at infinity, reference equipment, common to the said aircraft, for location on the ship, and including a three-axis reference inertial platform similar to the said inertial platform carried by each aircraft, means for operating the reference equipment so that in operation the platform is maintained level and orientated in a fixed known compass direction, and pickoff means for deriving signals from the reference platform to represent orthogonal components of the ship'"'"''"'"'s acceleration and velocity at the reference platform.
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8. In an inertial guidance system for aircraft based on a ship, where each aircraft carries a three-axis inertial platform including three single-axis gyros and two linear accelerometers with an associated navigational computer and providing in operation a head-up display of an aiming line at infinity, reference equipment common to the said aircraft, for location on the ship and including a three-axis reference inertial platform similar to the said inertial platform carried by each aircraft, means for operating the reference equipment so that in operation the reference platform is maintained level and orientated in a fixed known comPass direction, a sighting mark to be visible to the pilot of each aircraft through his head-up display where the aircraft is in position for take-off, means for determining the bearing of the sighting mark as viewed from each aircraft and the distance of the aircraft from the reference platform, means for deriving from the accelerometers of the reference platform signals to represent the North-South and East-West components of acceleration and velocity at the reference platform together with signals dependent on the rates of pitch-roll, and heading at the reference platform, and computing means for deriving from said signals and from the distance and bearing of the aircraft from the reference equipment the local velocity and acceleration components at the aircraft resolved into North-South and East-West directions.
Specification