## 5 Conclusions  
To evaluate the passive antiwetting performance of the aquatic-UAV model and verify its surface-based antiwetting performance using the properties of superhydrophilicity, we provided a quantitative simulated-precipitation system, and we inserted models of the aquatic UAV into the rain field by using a superhydrophobic cantilever to support the model and to connect it to a torque sensor and other instrumentation to evaluate the passive and dynamic antiwetting performance of the aquatic-UAV model with superhydrophobic surfaces to verify its surface-based antiwetting performance, and additionally, to compare the characteristics of an identical model with hydrophilic surfaces. We also performed numeric simulations and found the results to be similar to the experimental results. We conclude the following:  
1. The \"edge effect\" produced by the superhydrophobic surface significantly affects the mass redistribution within the droplet, so that the time for the first detachment of the derived droplet is reduced by 67% compared with the theoretical contact time, and the time required for complete detachment from the surface is reduced by 40%;
2. Compared with models with hydrophilic surfaces, the superhydrophobicity of the surface enables an 87.5% reduction in precipitation loading, so that the model behaviors are almost unaffected by precipitation;
3. The superhydrophobic surface has an excellent antiwetting effect when combined with model vibration and forward motion; the motion reduces the surface-droplet adhesion, accelerates the solid-liquid separation, produces directional bounce, and maintains flight stability;
4. LBM numerical simulations show that, in forward motion, the lateral-pressure distribution of the fluid on a model with hydrophilic surfaces is uneven, which affects the lateral mechanical balance of the aquatic UAV. The lateral-pressure distribution of the fluid on the model with superhydrophobic surfaces is relatively uniform, which is beneficial in maintaining flight balance;
5. A rain droplet falling onto a hydrophilic surface loses kinetic energy, which diminishes its chance of separation. After falling onto a superhydrophobic substrate, rain droplets can still maintain a high level of kinetic energy, the average absolute velocity is increased by up to 32%, and the derived droplets have enough kinetic energy to quickly separate, with no inclination to pin or adsorb onto the surface. The details of the superhydrophobicity can affect the direction of bounce favorably toward the rear of the craft.  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app12157626/s1](https://www.mdpi.com/article/10.3390/app12157626/s1)]([https://www.mdpi.com/article/10.3390/app12157626/s1](https://www.mdpi.com/article/10.3390/app12157626/s1)). References [5,20,34,41] are cited in the Supplementary Materials.  
[PERSON] and [PERSON] conceived the study. [PERSON], [PERSON] and [PERSON] conducted the experiments. [PERSON] performed the simulations. [PERSON] wrote the manuscript. All authors have read and agreed to the published version of the manuscript.  
This study was supported by the National Key Research and Development Program of China (Grant No. 2018 YFA0703300), the Guangxi Natural Science Foundation of China (Grant No. 2021 GXNSFBA075053), the Doctoral Research Fund of Guangxi Academy of Sciences (Grant No. 2021 YBJ702), and the National Natural Science Foundation of China (Grant No. 51875243).  
Not applicable.  
The data presented in this study are available upon request from the corresponding author.  
The authors declare no conflict of interest.