## 2 UAV Dynamics Model
### Dynamic Model Correction and Verification Based on Flight Tests  
The aerodynamic model modeling research and propeller slip influence experiment conducted in the previous section were carried out under zero free flow conditions. Although the parameter changes in the power at high speeds and the induced velocity of propeller slip under incoming flow conditions were extrapolated and corrected during the modeling process, the accuracy of the established model had not been verified yet. Therefore, this paper further designed the MY-UAV flight test and combined the flight test data to revise and verify the established aerodynamic and dynamic models. The designed drone flight test mainly includes three flight projects: normal taxiing takeoff, high-speed cruising, and low-speed large-angle climbing. Figure 12 shows the process of the MY-UAV drone flight experiment. Figure 12: Flight experiment process picture of MY-UAV: (**a**) rolling takeoff process; (**b**) low-speed and high-angle climb process in the air. In this flight experiment, the drone was powered by three sets of 6S batteries in parallel and equipped with an eagle power sensor for power acquisition. An unmanned aerial vehicle dynamics model was built using Matlab/Simulink, and the simulation results of the cruise process were compared with actual flight experiment data. The digital simulation results of the cruise section are shown in Figure 13:  
The simulation results show that the drone can fly at a constant altitude at 53% throttle opening, maintaining an angle of attack of 1.4\({}^{\circ}\), and an airspeed of 20.73 m/s, in good agreement with experimental flight data. To further verify the accuracy of the modified dynamic model, it was reapplied to the digital simulation experiment for taxiing takeoff. The simulation results are shown in Figure 14:  
Figure 13: Digital simulation results of cruise segment. (**a**) Cruise segment simulation—altitude; (**b**) cruise segment simulation—airspeed; (**c**) cruise segment simulation—angle of attack; (**d**) cruise segment simulation—throttle amount. The simulation results show that after taxiing off the ground, the drone can steadily climb at an airspeed of about 24.6 m/s, a climb rate of 5.3 m/s, and a pitch angle of 10.2\({}^{\circ}\), with a climb height of about 48 m within 10 s.  
After extracting data from the actual flight experiment of the drone during the taxiing and takeoff phase, as shown in Figure 15, it can be observed that the drone can steadily climb at an airspeed of approximately 25 m/s, a climb rate of 4.1 m/s, and a pitch angle of 10\({}^{\circ}\) after taxiing off the ground, with a climb height of approximately 43 m within 10 s.  
The results of the MY-UAV flight tests were compared and analyzed with the simulation results. The results indicate that the airspeed error during the stable climb phase of the MY-UAV does not exceed 4%, the climb rate error does not exceed 20%, and the pitch angle error does not exceed 7%. It can be seen that through the correction method of the above dynamic model, it can effectively ensure that the dynamic model has good agreement with the actual flight characteristics of the unmanned aerial vehicle, which further indicates that the established dynamic model has high reference value for subsequent takeoff and landing control of MY-UAV. Figure 14: Digital simulation results of takeoff climb phase. (**a**) Taxing takeoff simulation—altitude; (**b**) taxiing takeoff simulation—airspeed; (**c**) taxiing takeoff simulation—climb rate; (**d**) taxiing takeoff simulation—pitch angle. Performance Analysis and Control Strategy Design of Unmanned Aerial Vehicles During Rapid Ascent and Descent  
To meet the requirements of special mission scenarios, MY-UAV drones choose takeoff and landing methods of jumping and steep slope descent.