Wind Tunnel Model Trim via Feedback Control
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Solution Overview
Problem
Wind tunnel testing of aircraft, such as missiles, generates vast amounts of data due to the need to test a wide range of control surface positions, Mach numbers, and orientations, making the process time-consuming and inefficient.
Innovation Solution
Implementing a remotely controlled model in the wind tunnel that can automatically trim pitch, yaw, and roll moments by deflecting control surfaces, using digital feedback for control surface positions, and employing a feedback loop to adjust control surfaces based on forces and moments measured at the sting, allowing for faster determination of flight characteristics and trim conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large range of control surface positions, Mach numbers, and orientations are tested manually, then comprehensive flight characteristics are obtained, but the testing process becomes time-consuming and produces voluminous data
Solution Approach 1:
The wind tunnel test article automatically trims itself by using its own measured forces and moments to adjust control surface positions through a feedback control system, eliminating the need for manual trimming operations and significantly reducing testing time
Solution Approach 2:
A feedback control system continuously measures forces and moments on the test article, compares them to desired trim conditions, and automatically adjusts control surface positions to achieve and maintain trim across various flight conditions
2Measurement precision
If manual trimming of control surfaces is performed for each test condition, then trim accuracy is achieved, but the process requires extensive manual operation and processing time
Solution Approach 1:
The test article performs its own trimming operation by automatically interpreting measured forces and moments to determine required control surface adjustments, eliminating manual trimming operations while maintaining accuracy
Solution Approach 2:
The manual mechanical trimming process is replaced with an automated control system that uses sensors, computers, and actuators to perform trimming operations, reducing manual labor and processing time
3Measurement precision
If extensive wind tunnel testing is conducted to evaluate airframe configurations, then high-fidelity data is obtained, but the data processing becomes complex and time-consuming
Solution Approach 1:
The automated feedback control system continuously records trim data across multiple test conditions, organizing information systematically to reduce post-processing complexity and enable faster analysis of flight characteristics
Data Source
AI summary
A wind tunnel testing technique or method involves using feedback to position control surfaces of a model so that there is substantially no moment on the model for its given orientation to the airstream. The model is mounted on a sting that allows change in orientation of the model relative to the airstream. A balance is used to provide data regarding the forces and/or moments on the model. This data on forces and/or moments is used in one or more feedback loops to position the control surfaces of the model so that there are substantially no moments on the model. This may be done automatically, with a controller automatically controlling the position of the control surfaces to zero out the moments on the model. The use of the method may allow faster determination of model characteristics, such as determination of the trim envelope of the model.