US3735340A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stall warning system utilizing an electronic time delay
Assignee: AMERICAN AVIAT CORP
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Filing: 1970-04-10
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Granted: 1973-05-22
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Expires: 1990-04-10
Abstract
Abstract Astall warning system for an aircraft including means for providing a signal indicating that the airflow at an airfoil on the aircraft is about at its stagnation point, means for providing a warning signal responsive to the condition sensed by the sensing means, and means for inhibiting the actuation of the warning means for a predetermined short period of time after the stall condition is sensed. In a preferred embodiment, the inhibiting means includes an electronic time delay circuit comprising a source of electrical potential, a transistor switch in circuit with the source of potential and wit the sensing means, and charge storage means in circuit with the transistor switch for storing a charge having a first magnitude when the transistor switch is non-conductive and a second magnitude when the transistor switch is conductive. The conductivity of the transistor switch is controlled by the sensing means. The storage of charge at the second magnitude by the charge storage means causes a controlled transistor to conduct at a predetermined time after the transistor switch becomes conductive. When the controlled transistor conducts, the coil of a relay is energized to actuate a contactor switch in circuit with the warning device. Thus, the actuation of the warning device is delayed for a predetermined short period of time to eliminate inadvertent operation due to the sensing of a gusting air condition by the sensing means.
Inventors
- 👤 T Donnelly
- 👤 W Seidel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:35
CPC Classifications
G; G01; G01P; G01P5/00; G01P5/02; G01P5/04; B; B64; B64D; B64D43/00; B64D43/02; G01P1/00; G01P1/07; G01P1/08; G01P1/10
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
310 words
An electronic time delay circuit in combination with a stall warning system for an aircraft of the type including an airfoil, the system comprising the combination of: means for sensing a change in the airflow at said airfoil about the stagnation point for said aircraft and for providing a first signal indicative thereof, warning means actuatable by a second signal responsive to said first signal for providing a warning signal indicating that the airflow at said airfoil is at about its stagnation point, and means for inhibiting the actuation of said warning means for a predetermined period of time after said sensing means provides said first signal to prevent actuation of said warning means by spurious signals from said sensing means, wherein said inhibiting means comprises said electronic time delay circuit operatively connected to said sensing means and said warning means for providing said second signal to said warning means at a predetermined time after said first signal is provided by said sensing means, and wherein said electronic time delay circuit comprises: a source of electrical potential, a first transistor in circuit with said source of electrical potential, said transistor being biased in a normally nonconductive state, first means for causing said first transistor to become conductive, charge storage means in circuit with said first transistor for receiving a signal when said first transistor is rendered conductive, controlled transistor means in circuit with said charge storage means, said controlled transistor means being biased in a normally non-conductive state, said controlled transistor means being connected in circuit with said source of electrical potential when said first transistor is rendered conductive by said first means, said controlled transistor means being rendered conDuctive when said storage means receives said signal, and output means in circuit with said controlled transistor means for providing said second signal when said controlled transistor means is rendered conductive.
Claim 2
Dependent Claim
310 words
An electronic time delay circuit in combination with a stall warning system for an aircraft of the type including an airfoil, the system comprising the combination of: means for sensing a change in the airflow at said airfoil about the stagnation point for said aircraft and for providing a first signal indicative thereof, warning means actuatable by a second signal responsive to said first signal for providing a warning signal indicating that the airflow at said airfoil is at about its stagnation point, and means for inhibiting the actuation of said warning means for a predetermined period of time after said sensing means provides said first signal to prevent actuation of said warning means by spurious signals from said sensing means, wherein said inhibiting means comprises said electronic time delay circuit operatively connected to said sensing means and said warning means for providing said second signal to said warning means at a predetermined time after said first signal is provided by said sensing means, and wherein said electronic time delay circuit comprises: a source of electrical potential, a first transistor in circuit with said source of electrical potential, said transistor being biased in a normally nonconductive state, first means for causing said first transistor to become conductive, charge storage means in circuit with said first transistor for receiving a signal when said first transistor is rendered conductive, controlled transistor means in circuit with said charge storage means, said controlled transistor means being biased in a normally non-conductive state, said controlled transistor means being connected in circuit with said source of electrical potential when said first transistor is rendered conductive by said first means, said controlled transistor means being rendered conDuctive when said storage means receives said signal, and output means in circuit with said controlled transistor means for providing said second signal when said controlled transistor means is rendered conductive.
Claim 3
Dependent Claim
76 words
The circuit as defined in claim 1 further including a relay comprising a coil and a pair of contactors, said coil being in circuit with said controlled transistor means, and said contactors being in circuit with said warning means and said source of reference potential, said contactors being normally in a first condition and being switched to a second condition to actuate said warning means when said controlled means is rendered conductive to energize said coil.
Claim 4
Dependent Claim
75 words
The circuit as defined define in claim 2 wherein said first switch means is a first transistor normally biased in a non-conducting state, said signal storage means is the capacitor for receiving a first signal when said first transistor is not conducting, and for receiving a second signal when said first transistor is conducting, and wherein said controlled transistor means is a controlled rectifier which is rendered conductive when said capacitor receives said second signal.
Claim 5
Dependent Claim
44 words
The circuit as defined in claim 3 further including a diode in circuit with said source of electrical potential and said capacitor to cause said capacitor to receive a first signal corresponding to said source of electrical potential when said first transistor is non-conductive.
Claim 6
Dependent Claim
261 words
A stall warning system for an aircraft of the type including an airfoil comprising the combination of: means for sensing a change in a airflow at said airfoil about the stagnation point for said aircraft and for providing a first signal indicative thereof, warning means actuatable by a second signal responsive to said first signal for providing a warning signal indicating that the airflow at said airfoil is at about its stagnation point, and means for inhibiting the actuation of said warning means for a predetermined period of time after said sensing means provides said first signal to prevent actuation of said warning means by spurious signals from said sensing means, wherein said inhibiting means comprises electronic means in circuit with said sensing means and said warning means for providing said second signal to said warning means at a predetermined time after said first signal is provided by said sensing means, and wherein said electronic means comprises: a source of electrical signals, first electronic switch means in circuit with said source of electrical signals and said sensing means, said first electronic switch means being biased to a non-conductive state and being rendered conductive by said first signal, means for storing a signal at a first level when said first electronic switch means is non-conductive and at a second level when said first electronic switch means is conductive, and controlled transistor means in circuit with said signal storage means for providing said second signal in response to the storage of a signal at a second signal level by said signal storage means.
Claim 7
Dependent Claim
261 words
A stall warning system for an aircraft of the type including an airfoil comprising the combination of: means for sensing a change in a airflow at said airfoil about the stagnation point for said aircraft and for providing a first signal indicative thereof, warning means actuatable by a second signal responsive to said first signal for providing a warning signal indicating that the airflow at said airfoil is at about its stagnation point, and means for inhibiting the actuation of said warning means for a predetermined period of time after said sensing means provides said first signal to prevent actuation of said warning means by spurious signals from said sensing means, wherein said inhibiting means comprises electronic means in circuit with said sensing means and said warning means for providing said second signal to said warning means at a predetermined time after said first signal is provided by said sensing means, and wherein said electronic means comprises: a source of electrical signals, first electronic switch means in circuit with said source of electrical signals and said sensing means, said first electronic switch means being biased to a non-conductive state and being rendered conductive by said first signal, means for storing a signal at a first level when said first electronic switch means is non-conductive and at a second level when said first electronic switch means is conductive, and controlled transistor means in circuit with said signal storage means for providing said second signal in response to the storage of a signal at a second signal level by said signal storage means.
Claim 8
Dependent Claim
76 words
The system as defined in claim 5 further including a relay comprising a coil and a pair of contactors, said coil being in circuit with said controlled transistor means, and said contactors being in circuit with said warning means and said source of reference potential, said contactors being normally in a first condition and being switched to a second condition to actuate said warning means when said controlled means is rendered conductive to energize said coil.
Claim 9
Dependent Claim
74 words
The system as defined in claim 6 wherein said first switch means is a first transistor normally biased in a non-conducting state, said signal storage means is the capacitor for receiving a first signal when said first transistor is not conducting, and for receiving a second signal when said first transistor is conducting, and wherein said controlled transistor means is a controlled rectifier which is rendered conductive when said capacitor reCeives said second signal.
Claim 10
Dependent Claim
44 words
The system as defined in claim 7 further including a diode in circuit with said source of electrical potential and said capacitor to cause said capacitor to receive a first signal corresponding to said source of electrical potential when said first transistor is non-conductive.
Claim 11
Dependent Claim
51 words
The circuit as defined in claim 1 further including unidirectional conducting means in circuit with said storage means and said source of reference potential so that the said storage means receives said first signal when said first transistor is non-conductive and receives said second signal when said first transistor is conducting.
Claim 12
Dependent Claim
62 words
The circuit as defined in claim 1 wherein said output means includes a relay coil in circuit with said controlled transistor means, said coil being energized when said controlled transistor means is rendered conductive, and contactors which are normally in a first condition of contact and which are caused to change to a second condition of contact when said coil is energized.
Claim 13
Dependent Claim
37 words
The circuit as defined in claim 9 further including a warning device in circuit with said contactors in such a manner that said warning device is actuated when said contactors are caused to change to said condition.
Claim 14
Dependent Claim
14 words
The circuit as defined in claim 10 wherein said first means is a switch.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-05-21 | 1976-11-20 | 1977-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-21 | 1980-11-20 | 1981-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-21 | 1984-11-20 | 1985-05-22 | $7700.00 | Window Closed / Lapsed |