Auto Referencing AirBOS for Off-Axis Shock Wave Measurement
Solution Overview
Problem
Traditional AirBOS techniques require high frame rate cameras and target aircraft overtake for optimal results, limiting off-axis data collection and increasing pilot workload and safety risks.
Innovation Solution
An auto-referencing AirBOS method where a sensor aircraft flies in formation with the target aircraft, capturing paired images to compute background distortions caused by refractive wake features, allowing for off-axis data collection without overtaking and using lower frame rate, high-resolution cameras.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional AirBOS uses high frame rate cameras and target aircraft overtake, then measurement precision of shock waves is improved, but device complexity and pilot workload increase
Solution Approach 1:
The sensor aircraft captures reference images of the background before the target aircraft arrives at each position. This preliminary capture of reference data eliminates the need for complex real-time processing during overtake maneuvers, allowing standard frame rate cameras to achieve the same measurement precision as high-speed cameras would require in traditional methods.
Solution Approach 2:
The method extracts the reference background images separately from the measurement process. By capturing reference images independently before the target aircraft passes, the system removes the requirement for high frame rate cameras during the critical measurement phase, thereby reducing device complexity while maintaining measurement precision.
2Measurement precision
If traditional AirBOS requires target aircraft overtake, then measurement precision is improved, but ease of operation deteriorates due to increased pilot workload and safety risks
Solution Approach 1:
Reference images are captured in advance during a separate reconnaissance flight or before the target aircraft reaches each measurement position. This preliminary capture eliminates the need for precise overtake maneuvers during actual measurements, significantly reducing pilot workload and safety risks while preserving measurement precision through subsequent image comparison.
Solution Approach 2:
The measurement process is segmented into two independent phases: (1) capturing reference background images during calm conditions before target arrival, and (2) capturing measurement images during target passage. This segmentation allows each phase to be optimized independently, eliminating the need for complex coordinated overtaking maneuvers while maintaining measurement quality.
3Measurement precision
If traditional AirBOS uses fixed nadir view, then measurement precision for vertical shocks is improved, but adaptability to off-axis measurements deteriorates
Solution Approach 1:
The sensor aircraft's viewing angle is made dynamic rather than fixed at nadir. By allowing the sensor aircraft to position itself at various angles and distances from the target aircraft's flight path, the system can capture oblique views of shock waves and density gradients, thereby extending adaptability to off-axis measurements while maintaining measurement precision through the reference image comparison method.
Solution Approach 2:
The measurement capability is extended from purely vertical (nadir) views to three-dimensional spatial configurations. By capturing reference images from multiple angular positions and combining them with measurement images, the system gains adaptability to measure oblique and off-axis flow phenomena while preserving the precision benefits of the AirBOS technique.
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
Facilitates easier off-axis data collection, reduces pilot workload, enhances mission safety, and expands camera options, enabling higher resolution schlieren imagery without high-speed camera requirements.
Implementation Method 1
Air density gradients cause a refractive index change in the fluid that can cause a slight distortion in the background pattern of the data image
Data Source
AI summary
An air-to-air background-oriented schlieren system in which reference frames are acquired concurrently with the image frames, recording a target aircraft from a sensor aircraft flying in formation, while concurrently recording reference frames of underlying terrain to provide a visually textured background as a reference. This auto-referencing method improves the original AirBOS method by allowing a much more flexible and useful measurement, reducing the flight planning and piloting burden, and broadening the possible camera choices to acquire imaging of visible density changes in air that cause a refractive index change by an airborne vehicle.