Aircraft Airspeed Calculation Without Static Port Pressure Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft airspeed measurement is compromised during near-ground or on-ground operations due to contamination of external static ports, necessitating a method that does not rely solely on direct measurements from these ports for accurate airspeed determination.
Innovation Solution
The system utilizes GPS altitude measurements and inertial reference system data to calculate a geometric altitude rate of change, which, combined with pressure altitude rate of change, determines a static pressure value, allowing for airspeed calculation without relying on external static ports, using a computer system connected to GPS, inertial reference, and other sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external static ports are used for direct airspeed measurement, then measurement simplicity is maintained, but measurement precision deteriorates due to contamination during near-ground operations
Solution Approach 1:
The patent introduces an intermediary calculation method that uses GPS altitude measurements and inertial reference system data as mediators to derive static pressure information indirectly. Instead of directly measuring static pressure through contaminated ports, the system uses GPS altitude rate of change and vertical acceleration as intermediate parameters to calculate equivalent static pressure, thereby avoiding the harmful effect of port contamination while maintaining measurement accuracy.
Solution Approach 2:
The patent replaces the mechanical direct measurement system (static ports and pressure sensors) with a computational system using GPS and inertial reference data. By substituting the mechanical measurement approach with a computational approach that processes GPS altitude and acceleration data, the system eliminates the physical static ports that are susceptible to contamination, thereby resolving the contradiction between measurement simplicity and accuracy.
2Reliability
If direct static pressure measurement is used, then device complexity is minimized, but reliability deteriorates during near-ground operations
Solution Approach 1:
The patent makes the GPS and inertial reference systems perform multiple functions. These systems, originally designed for navigation and attitude determination, are also used to derive static pressure information for airspeed measurement. By enabling these existing systems to serve dual purposes, the patent improves reliability without significantly increasing device complexity, as the same hardware components are utilized for multiple measurement objectives.
Solution Approach 2:
The system uses its own existing sensors (GPS and inertial reference) to provide the static pressure information needed for airspeed determination. Instead of relying on separate static port measurements that may be contaminated, the system serves itself by deriving the necessary pressure data from its own navigation and attitude sensors, thereby improving reliability while avoiding the need for additional contaminated external ports.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Aircraft and methods and systems for determining airspeed of an aircraft. The methods and systems allow for calculation of airspeed in near-ground and on-ground aircraft operation. A GPS altitude and a vertical acceleration of the aircraft are obtained for a current time frame. A geometric altitude for the previous time frame is determined, and the difference between the GPS altitude and geometric altitude are combined with the vertical acceleration to calculate a geometric altitude rate of change. The geometric altitude rate of change is used to calculate a pressure altitude rate of change, which is used to calculate a pressure altitude for the aircraft. A static pressure is calculated from the pressure altitude, and the airspeed is calculated using the static pressure.