Flight Computer Airspeed Estimation Without Pitot Probes
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Solution Overview
Problem
Aircrafts, especially small unpowered vehicles like gliders, face challenges in accurately determining airspeed due to size and weight constraints of traditional measurement methods, which often require expensive and bulky probes.
Innovation Solution
A method using an accelerometer on the vehicle to determine body-fixed load factor measurements, calculate the angle-of-attack parameter, and derive airspeed without the need for pitot-static systems, employing equations that relate load factors to airspeed and body-force coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pitot-static probes are used to measure airspeed, then measurement precision is improved, but device complexity and weight increase
Solution Approach 1:
The patent extracts the airspeed measurement function from the traditional pitot-static probe system and relocates it to an accelerometer-based computational system. By removing the physical probe requirement and implementing airspeed calculation through sensor fusion of accelerometer data with aerodynamic models, the solution eliminates bulky external probes while maintaining measurement capability through mathematical derivation from load factor measurements.
Solution Approach 2:
The patent replaces the mechanical pitot-static probe system with an electronic/computational system using accelerometers and flight computer algorithms. Instead of mechanically measuring pressure differences through probes, the system uses electronic sensors to measure load factors and computationally derives airspeed through equations of motion and aerodynamic coefficient models, substituting mechanical measurement with electronic sensing and mathematical computation.
2Measurement precision
If precise inertial measurements are used to estimate airspeed, then measurement precision is improved, but weight and expense increase
Solution Approach 1:
The patent changes the measurement parameters from direct pressure-based measurements (requiring heavy probes) to acceleration-based measurements using lightweight accelerometers. By transforming the measurement approach from static pressure differential to dynamic load factor measurement, the system achieves airspeed estimation using lighter inertial sensors combined with computational aerodynamics, reducing weight while maintaining precision through mathematical modeling.
3Measurement precision
If external probes are used for airspeed measurement, then measurement precision is improved, but ease of operation deteriorates due to size constraints
Solution Approach 1:
The patent makes the accelerometer system multi-functional by using it for both attitude/acceleration measurement and airspeed estimation. The same inertial measurement unit that provides basic flight data also enables airspeed calculation through computational methods, eliminating the need for separate probe systems and making the solution applicable to small vehicles where space is constrained.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate airspeed determination and flight profile generation for unpowered vehicles, optimizing trajectory and lift-to-drag ratios for maximum distance coverage without the use of bulky probes, and can correct airspeed and angle-of-attack in real-time.
Implementation Method 1
determining, by an accelerometer disposed on the unpowered vehicle, first and second accelerometer outputs, where the first and second accelerometer outputs correspond to respective first and second body-fixed load factor measurements
Data Source
AI summary
According to one implementation of the present disclosure, a method for determining airspeed for an unpowered vehicle is disclosed. The method includes: determining first and second body-fixed load factor measurements; determining a body Z-force coefficient based on an angle-of-attack parameter; and determining an airspeed value based on the second body-fixed load factor measurement and the body Z-force coefficient.