US4250746A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Aircraft instrument
Assignee: British Airways PLC
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Filing: 1979-07-09
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Granted: 1981-02-17
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Expires: 1999-07-09
Abstract
Abstract A combined vertical speed and windshear indicator instrument for an aircraft has a graduated dial (2) and a conventionally driven pointer (3) for indicating the vertical speed. In addition the instrument has an independent pointer (4) which is driven so that it indicates, to the same scale as the vertical speed, the rate of change of total energy of the aircraft (energy rate) according to the formula dh/dt+(V/g)(dV/dt) where h is the height of the aircraft and V is its true air speed. Under stable flight conditions the pointers (3 and 4) will track together, but if there are any sudden changes, particularly changes due to windshear, the pointers will separate to indicate the effect of the changes so that the necessary corrective action can be taken by the pilot. The energy rate pointer (4) is driven by a signal (22) derived from input signals (5 and 6) which respectively represent the vertical speed h and the true air speed V of the aircraft and which are delayed by the use of filters (10, 14 and 20 ) for reducing noise interference. The response time of the energy rate pointer (4) to sudden acceleration of the aircraft itself is therefore improved by deriving the (dV/dt) term of the energy rate drive signal (22), for a short period following the sudden acceleration, from a signal (24) representative of the longitudinal acceleration x of the aircraft.
Inventors
- 👤 Craig D. Vassie
- 👤 Alexander B. Fisher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:50
CPC Classifications
G; G01; G01P; G01P5/00; G01C; G01C5/00; G01C5/005; G01P15/00; G05; G05D; G05D1/00; G05D1/04; G05D1/06; G05D1/0607
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
209 words
In a vertical speed indicator instrument for an aircraft, said instrument comprising a graduated dial, a first pointer, and first control means for controlling said first pointer to indicate the vertical speed of the aircraft on said dial, said first control means including height rate responsive means responsive to a first input signal representative of the rate of change of height of the aircraft, the improvement wherein said instrument also comprises a second pointer movable independently of said first pointer, said second control means including said height rate responsive means and airspeed responsive means responsive to a second input signal representative of the true airspeed of said aircraft, said second control means controlling said second pointer and causing said second pointer to move in response to changes in the rate of change of the total energy of the aircraft as defined by the formula ##EQU2## where h is the height and V is the true airspeed of the aircraft, said second pointer indicating the energy rate of change on said dial to the same scale as said vertical speed whereby said first and second pointers will track together under steady flight conditions but will separate from each other in response to sudden changes in the airspeed of said aircraft.
Claim 2
Dependent Claim
209 words
In a vertical speed indicator instrument for an aircraft, said instrument comprising a graduated dial, a first pointer, and first control means for controlling said first pointer to indicate the vertical speed of the aircraft on said dial, said first control means including height rate responsive means responsive to a first input signal representative of the rate of change of height of the aircraft, the improvement wherein said instrument also comprises a second pointer movable independently of said first pointer, said second control means including said height rate responsive means and airspeed responsive means responsive to a second input signal representative of the true airspeed of said aircraft, said second control means controlling said second pointer and causing said second pointer to move in response to changes in the rate of change of the total energy of the aircraft as defined by the formula ##EQU2## where h is the height and V is the true airspeed of the aircraft, said second pointer indicating the energy rate of change on said dial to the same scale as said vertical speed whereby said first and second pointers will track together under steady flight conditions but will separate from each other in response to sudden changes in the airspeed of said aircraft.
Claim 3
Dependent Claim
34 words
An instrument as defined in claim 1 wherein said first and second pointers are formed by pivoted needles which are mounted to turn independently about a common axis at the center of said dial.
Claim 4
Dependent Claim
24 words
An instrument as defined in claim 1, wherein said height rate responsive means and said airspeed responsive means are responsive to digital input signals.
Claim 5
Dependent Claim
58 words
An instrument as defined in claim 1, wherein said airspeed responsive means includes differentiating means for deriving from said second input signal a derivative signal representative of the rate of change of the airspeed, means for multiplying together said second input signal and said derivative signal, and means for adding the multiplied signal to said first input signal.
Claim 6
Dependent Claim
43 words
An instrument as defined in claim 4, wherein said airspeed responsive means includes first and second filters for damping said second input signal and said derivative signal respectively before said second input signal and said derivative signal are multiplied by said multiplying means.
Claim 7
Dependent Claim
74 words
An instrument as defined in claim 5, wherein said height rate responsive means includes third and fourth filters for separately damping said first input signal so that signal so that said height rate signal used by said second control means is delayed by a different amount from said height rate signal used by said first control means and matches said multiplied signal to which said first input signal is added by said adding means.
Claim 8
Dependent Claim
78 words
An instrument as defined in claim 5, wherein said second control means includes means for modifying said derivative signal in response to a signal representative of the longitudinal acceleration of the aircraft to improve the response time of said second pointer to sudden accelerations, said modifying means comprising a filter which receives said longitudinal acceleration signal and which is the wash-out of said second filter for damping said derivative signal, and means for adding said filtered derivative signal.
Claim 9
Dependent Claim
19 words
An instrument as defined in claim 7, wherein said instrument includes an accelerometer for providing said longitudinal acceleration signal.
Claim 10
Dependent Claim
44 words
An instrument as defined in claim 4, wherein said second control means includes means for modifying said derivative signal in response to a signal representative of the longitudinal acceleration of said aircraft to improve the response time of said second pointer to sudden accelerations.
Claim 11
Dependent Claim
46 words
An instrument as defined in claim 1, wherein said second control means includes acceleration responsive means which is responsive, in the short term, to a signal representative of the longitudinal acceleration of said aircraft to improve the response time of said second pointer to sudden accelerations.
Claim 12
Dependent Claim
79 words
An instrument as defined in claim 1, wherein said height rate responsive means and said airspeed responsive means include filter means for damping said first and second input signals, and said second control means also includes acceleration responsive means which is responsive, in the short term to a signal representative of the longitudinal acceleration of the aircraft to compensate for delays caused by said filter means and thereby improve the response time of said second pointer to sudden accelerations.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-17 | 1984-08-18 | 1985-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-17 | 1988-08-18 | 1989-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-17 | 1992-08-18 | 1993-02-17 | $7700.00 | Window Closed / Lapsed |