Communications: electrical – Aircraft alarm or indicating systems – Flight alarm
Utility Patent
1998-12-09
2001-01-02
Lee, Benjamin C. (Department: 2736)
Communications: electrical
Aircraft alarm or indicating systems
Flight alarm
C340S965000, C340S963000, C340S970000, C340S957000, C701S009000, C701S015000, C701S016000, C244S179000, C244S180000, C244S181000
Utility Patent
active
06169496
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
(Not Applicable)
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
(Not Applicable)
FIELD OF THE INVENTION
This invention relates to aircraft flight control systems. More particularly, this invention relates to a new and improved system and method for indicating the availability of theoretically safe return path to a landing field after a power failure and for indicating whether the airplane is subjected to restricted lateral maneuvering during powered or non-powered flight.
BACKGROUND OF THE INVENTION
A particularly serious scenario that can occur during the operation of an aircraft is sudden power failure at low altitudes, as with returning to a landing field or during takeoff, and commonly known as stall spin failures. Flight training schools currently teach that for power failures on takeoff a pilot should attempt a straight-ahead landing. Often, a more appropriate action for a pilot to take is to return to the field from which the pilot originally took off because of the potential difficulties presented by such a landing, including but not limited to, obstructions, landing on water, and hilly terrain. This particular maneuver is commonly known as a “Turnback” or a “Tear-Drop” return.
A properly executed Turnback procedure requires the pilot to immediately decrease the aircraft pitch a few degrees below the horizontal. The pilot is also required to execute a turn around a “Stall Cylinder”. A Stall Cylinder is an imaginary cylinder to which the aircraft should always be tangent. The diameter of the Stall Cylinder is a function of the speed of the aircraft, the particular aircraft's aerodynamic characteristics, and the pitch-down angle chosen by the pilot such that if the aircraft enters the Stall Cylinder boundary, the aircraft will lose sufficient lift and thus stall. Therefore, to maintain a safe path, the pilot must execute the turn around the Stall Cylinder without penetrating the Stall Cylinder. The pilot continues the turn at the appropriate constant pitch and bank angles until the aircraft has traveled approximately 240 degrees around the Stall Cylinder. At this point, the pilot rolls the aircraft to zero bank angle and establishes a straight-line descent to the field.
Although a Turnback may be the most appropriate action to take in the situation of a sudden power failure at takeoff, the Turnback maneuver itself can be deadly. Several factors, including panic and the pilot's lack of attention to the aerodynamics involved, lead to the hazardous nature of this maneuver. For example, a minimal starting altitude, depending upon the type of aircraft, is required before the maneuver can be accomplished. If the maneuver is attempted at a starting altitude below the minimum, either the pilot will fail to reach the field or the pilot may enter into the Stall Cylinder in an attempt to hurry the turn, thereby creating a stall condition. Also, even when an adequate starting altitude is present, the panic that ensues after a power failure can lead some pilots to neglect instrumentation and aircraft performance. In such situations, the pilot may attempt to return quickly to the take off field to land the aircraft, and in so doing executes such a tight turn that brings the aircraft within the Stall Cylinder which results in a stall of the aircraft or “stall spin”. Statistics from the National Transportation and Safety Board (NTSB) indicate that 72% of all “stall spin” accidents are fatal.
One device for a stall avoidance system is disclosed in U.S. Pat. No. 4,590,475 to Brown. The Brown patent discloses a stall avoidance system for aircraft. The system uses flight measurements such as acceleration, aircraft configuration, engine power, atmospheric conditions and other related characteristics in computing the speed at which a specific aircraft is likely to stall in real time. The system includes an audible warning to inform a pilot when conditions are approaching the projected stall speed. However, the Brown device requires considerable aircraft specific information to be inputted manually including weight, detailed wing surface area, detailed tail surface area, engine thrust, known stalling angle of attack, and known stalling speed. This system also requires nearly a dozen sensors. Because of the system's complexity it is expensive and it cannot be easily retrofitted into a light aircraft. The system may also require wind tunnel testing for each aircraft type. Additionally, this system does not provide guidance to a pilot in accomplishing a safe landing.
A method of predicting the approaching stall of an aircraft wing is disclosed in U.S. Pat. No. 4,563,684 to Marris. The Marris patent discloses an apparatus that senses airspeed fluctuations over the top surface of a wing and uses that information to determine whether a stall condition is impending. However, as with the Brown device, the Marris device does not provide guidance to a pilot in accomplishing a safe landing.
Thus, there is not any aircraft flight control system specifically designed as a safety device that currently indicates to the pilot whether a safe maneuver can be accomplished after a sudden power failure has occurred or any aircraft flight control system that calculates a safe glide path and communicates that flight path information so that the aircraft can be landed safely.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a stall warning system that indicates a glide path after a sudden power failure has occurred.
It is another object of this invention to provide a stall warning system that calculates a safe flight path and communicates that path information to either the pilot or aircraft such that the aircraft can be directed to follow that flight path. The flight information can be provided either electronically, visually, and/or audibly.
It is yet another object of this invention to provide a stall warning system that displays parameters useful during normal flight.
It is still another object of this invention to provide a stall warning system that can be installed with minimal intrusion into an aircraft.
Another object of this invention is to provide a stall warning system that warns the pilot when aircraft limits are about to be exceeded in any near constant altitude flight, whether powered or not, when restricted lateral maneuvering occurs.
In accordance with the invention, these and other objects are accomplished by providing a plurality of sensors for describing a flight path and stall conditions as an aircraft takes off from a field and a computer processor responsive to the plurality of sensors for determining the existence of a theoretically safe return path to the field after a power failure. The departure flight path and stall conditions to be derived from the plurality of sensors can be altitude, bank angle, and stall bank angle, and these sensors can include an outside temperature probe for sensing outside temperature; a gyroscope for sensing bank angle; a static transducer for sensing static pressure; and a dynamic pressure sensor for receiving total/static pressure from a pitot tube in the aircraft. The plurality of sensors can also include an engine system sensor for sensing whether the engine has ceased to provide power to the aircraft.
A recording device can also be added for recording information received from the plurality of sensors. An output device such as an indicator lamp can also be included for indicating the existence of the theoretically safe glide path. The indicator lamp can also indicate whether the aircraft is following the theoretically safe glide path. The output device can also include auditory alarms for indicating the theoretically safe flight path or whether the aircraft is following the theoretically safe glide path. The output device can also include a graphical and/or digital displays to display flight path characteristics including: outside air temperature; altitude; banking load factor; calibrated airspeed; true airspeed; stall bank angle; stall speed; bank angle; corrected st
Baciak Mark G.
Martin Mack L.
Seiler Louis W.
Exigent International, Inc.
Lee Benjamin C.
Senterfitt Akerman
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