# Research on the Flight Performance of Biomimetic Moth Based on Flapping Function Control
## 4 Flight Experiment and Result Analysis of Biomimetic Flapping-Wing Aircraft
### Experiment Scheme and Process  
In Section 3, a virtual wind tunnel simulation calculation platform was built to qualitatively study the impact of flapping parameters on the aerodynamic performance of flapping-wing aircraft. In this chapter, the biomimetic flapping-wing aircraft will be flight-tested to verify the accuracy of the simulation results.  
Through mathematical modeling and simulation calculation analysis, it can be seen that flapping amplitude and flapping frequency are the key influencing factors of lift generation of flapping motion, while the impact of mid-position angle on lift is not clear and needs further study. Therefore, the experiment will be divided into three parts: lift test, turning test, and flight altitude test.  
For flapping amplitude, a lift test is designed to explore its impact on the flight capability of the flapping-wing aircraft, and a turning test is designed to explore its impact on the amplitude difference turning capability. For flapping frequency, only a lift test is designed to explore its impact on the flight capability of the flapping-wing aircraft. For the mid-position angle, a lift test is designed to explore its impact on the flight capability of the flapping-wing aircraft, and at the same time, a flight altitude test is designed to explore the impact of the change of the absolute value of the mid-position angle during flight on the flight capability. The experiment process is shown in Figure 12.  
The experimental scheme is designed as follows:  
1. **Experimental Site:** The authors of [28] point out that gusts, or sudden changes in wind speed, can exert a certain influence on aspects such as the aircraft's attitude control. In fact, the flapping-wing aircraft prototype is greatly affected by natural wind, so an indoor environment with almost no wind is chosen as the experimental site. In addition, since the controller and the aircraft communicate wirelessly, it is necessary to ensure there is no electromagnetic interference. Ultimately, we chose a square indoor space measuring 12 m in both the \(x\)-axis and \(y\)-axis directions, which were windless and free from electromagnetic interference. The flapping-wing aircraft was released at a height of approximately 1.8 m above the ground;
2. **Experimental Content:** The experiment will primarily consist of three sections: lift test, turning test, and flight altitude test. The lift test explores the impact of flapping amplitude, flapping frequency, and mid-position angle on the aircraft's flight capability; the turning test explores the amplitude difference turning capability; and the flight altitude test explores the control of the flight altitude of the flapping-wing aircraft;  
Figure 11: Flight Control Architecture.  
3. **Experimental Recording Method:** The flapping-wing aircraft is not equipped with sensors related to aerodynamics, and the flight capability of the flapping-wing aircraft is challenging to quantify. The experimental process will use video recording, with the camera placed on a fixed tripod for a fixed shooting position;
4. **Data Analysis:** The position of the flapping-wing aircraft every 0.1 s in the experimental video is superimposed on the same negative, and a Bezier curve is drawn to plot the flight trajectory of the flapping-wing aircraft, then the flight capability of the flapping-wing aircraft is evaluated;
5. **Benchmark Parameters:** A large number of flight tests have shown that when the flapping amplitude is about 54\({}^{\circ}\), the flapping frequency is about 4 Hz, the mid-position angle is about 5\({}^{\circ}\), and the initial pitch angle is about 10\({}^{\circ}\), the flapping-wing aircraft has excellent flight performance. Therefore, the flight experiment will take these parameters as the benchmark parameter, and on this basis, the parameters will be changed, and the impact of each parameter on the flight performance will be analyzed.