Airspeed Conversion Modeling for Accurate Future Trajectory Estimates
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Solution Overview
Problem
Current methods for converting between Calibrated Airspeed (CAS) and True Airspeed (TAS) are computationally intensive and prone to significant errors, especially on non-standard days, with the 'rule of thumb' method producing large errors at high altitudes and varying atmospheric conditions.
Innovation Solution
An avionics system with data processors that generates calibrated airspeed, converts it to true airspeed, determines an initial approximate relationship based on pressure altitude, and adjusts this relationship to estimate future airspeeds, using a combination of linear and second-order curve fit approximations to reduce computational intensity and improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the full TAS to CAS equation is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent transforms the complex TAS to CAS conversion problem by changing the approach from direct calculation to iterative approximation. It uses initial guesses and refines them through multiple iterations, converting a single complex computational step into multiple simpler steps that converge to the accurate solution.
Solution Approach 2:
The patent applies preliminary action by using the rule of thumb method to generate initial TAS estimates before refining them. This preliminary approximation provides a starting point that is then improved through iterative calculations, reducing the computational burden compared to starting from scratch.
2Ease of operation
If the rule of thumb method is used, then ease of operation is improved, but measurement precision deteriorates
Solution Approach 1:
The patent makes the airspeed conversion method dynamic by implementing iterative refinement. Instead of using a static rule of thumb formula, the system dynamically adjusts the TAS estimate through multiple iterations, adapting the calculation to achieve both simplicity and accuracy.
Solution Approach 2:
The patent applies feedback by using the initial TAS estimate to calculate CAS, then comparing this calculated CAS with the actual CAS to determine the error. This feedback loop allows the system to refine the TAS estimate in subsequent iterations, improving accuracy while maintaining computational simplicity.
Data Source
AI summary
Systems, methods, aircraft, non-transitory media, and memories are provided. An avionics system for an aircraft includes a storage device and one or more data processors. The storage device stores instructions for converting between airspeed types and the one or more data processors is configured to execute the instructions to: generate a calibrated airspeed of the aircraft; convert the calibrated airspeed to an actual true airspeed of the aircraft; determine an initial approximate relationship between the calibrated airspeed and a computed true airspeed as a function of a pressure altitude of the aircraft; generate an adjusted approximate relationship based on the actual true airspeed and the initial approximate relationship at a chosen pressure altitude; and estimate a future airspeed of the aircraft based on the adjusted approximate relationship and a future altitude.