Accelerometer-Based Airspeed Estimation for Unpowered Flight
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Solution Overview
Problem
In aerospace applications, accurately determining airspeed for small unpowered vehicles like gliders is challenging 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 an angle-of-attack parameter, and derive an airspeed value based on these measurements, eliminating the need for pitot-static systems and probes.
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 calculation system mounted on the vehicle body. This eliminates the need for external probes while maintaining measurement capability through alternative physical principles (accelerometer measurements combined with flight dynamics calculations).
Solution Approach 2:
The patent replaces the mechanical probe-based measurement system with an electronic accelerometer-based system. Instead of using physical probes to directly sense airspeed, the system uses accelerometers to measure load factors and combines these with flight dynamics models to calculate airspeed, thereby substituting a mechanical sensing approach with an electronic computation approach.
2Measurement precision
If external probes are used for airspeed measurement, then measurement precision is improved, but weight increases
Solution Approach 1:
The patent removes the external probe components from the vehicle system and extracts the measurement function to be performed by onboard accelerometers and flight computer, thereby eliminating the additional weight of probes while maintaining airspeed determination capability.
3Measurement precision
If accurate inertial measurements are used to determine airspeed, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the accelerometer serve multiple functions: it provides both the primary measurement data for airspeed calculation and contributes to overall flight dynamics analysis. By using the same sensor for multiple purposes, the system avoids the need for separate dedicated airspeed sensing equipment, thereby reducing overall system complexity while maintaining precision.
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 without external probes, allowing for optimized flight profiles and improved lift-to-drag ratios, enhancing distance coverage and trajectory optimization.
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: during flight, 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; determining an angle-of-attack parameter; determining a body Z-force coefficient based on the angle-of-attack parameter; and determining an airspeed value based on the second body-fixed load factor measurement and the second body-fixed coefficient.