Flight-Path Angle Calculation Using GPS and Airspeed
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Solution Overview
Problem
Existing methods for determining the angle of attack (AOA) in airplanes rely on inaccurate airflow measurements or require physical modifications, leading to potential wing stall issues due to erroneous weight estimations and airflow representation.
Innovation Solution
A method using indicated airspeed and vertical velocity from GPS data to calculate the flight-path angle, which is then used in a basic aerodynamic equation to determine the AOA, providing accurate and direct AOA information to pilots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a vane is used to measure AOA, then direct AOA measurement is achieved, but the measurement accuracy deteriorates because local air flow does not represent true free air flow
Solution Approach 1:
The patent uses GPS-derived flight path angle as an intermediary to calculate AOA indirectly, avoiding the use of local airflow sensors that provide inaccurate direct measurements. The flight path angle serves as a mediator between available data (airspeed, vertical velocity) and the desired AOA information.
Solution Approach 2:
The patent replaces the mechanical vane system with an electronic calculation system using GPS and airspeed data. This substitution eliminates the physical sensor that causes measurement errors while achieving the same informational goal through mathematical computation.
2Adaptability or versatility
If static and/or dynamic air pressure sensors are installed on the airplane exterior, then AOA measurement capability is achieved, but device complexity and installation difficulty increase due to required physical modifications
Solution Approach 1:
The patent makes the existing airspeed indicator and GPS systems serve the additional function of AOA determination. By using data already collected by these universal systems, the patent eliminates the need for dedicated AOA sensors and their associated installation complexity.
Solution Approach 2:
The patent enables the existing aircraft systems (airspeed indicator, GPS) to provide AOA information for themselves through calculation. The system uses its own existing data to generate additional useful information without requiring external additions or modifications.
3Device complexity
If indicated airspeed is used alone to estimate wing stall speed, then simplicity is maintained, but reliability deteriorates due to erroneous weight estimations
Solution Approach 1:
The patent provides continuous feedback of actual AOA to the pilot, enabling real-time awareness of proximity to stall conditions. This feedback loop replaces static weight-based estimates with dynamic, actual flight condition monitoring, significantly improving reliability.
Solution Approach 2:
The patent calculates and displays AOA information in advance before stall conditions develop, allowing the pilot to take preventive action. By providing continuous AOA monitoring rather than reactive responses, the system enables proactive stall avoidance.
Data Source
AI summary
The angle of attack (AOA) of an airplane is calculated as the difference of the flight-path angle and the pitch angle. The pitch angle is available from an attitude monitoring device (e.g., pitch gyro), but the flight-path angle is not available from the basic instruments common in general aviation. This method determines the flight-path angle mathematically, and in particular, using inputs from indicated airspeed and GPS. The sine (trig function) of the flight-path angle is the value determined by dividing the vertical velocity, provided by onboard GPS, by the velocity along the flight path (e.g., indicated airspeed). The sine value is converted to the value of flight-path angle by referring to a sine lookup table.