Submerged Dragon 2 AUV
Submerged Dragon (Qian-Long, 潜龙) 2 autonomous underwater vehicle (AUV) is a very little known autonomous underwater vehicle (AUV) developed in the People's Republic of China (PRC) by Shenyang Institute of Automation (SIA) of Chinese Academy of Sciences (CAS),and it is developed from earlier Submerged Dragon 1 AUV, both are members of Submerged Dragon series AUV (also referred as Hidden Dragon based on translation). Submerged Dragon 2. Submerged Dragon 2 AUV is the second member of Submerged Dragon series UAV, and it is developed to operate in spaces where Submerged Dragon 1 cannot effectively  operate, namely, the mountainous terrain on seabed, where in the deep criss-crossing trenches and ravines of seamounts, vertical maneuverability matters more than the horizontal maneuverability. Therefore, although it is a development of earlier Submerged Dragon 1 AUV, it looks drastically different than its predecessors: instead of the torpedo-shaped cylindrical hull of Submerged Dragon 1, Submerged Dragon 2 adopts a fish-shaped hull.The reason for adopting a totally different hull form from its predecessor is the result of huge amount of hydrodynamic calculation and analysis, and the fish-shaped hull form enables Submerged Dragon 2 to have better  vertical maneuverability than Submerged Dragon 1.Submerged Dragon is also equipped with forward-looking imaging sonar.The general designer of Submerged Dragon 2 is Mr. Liu Jian (刘健),and Submerged Dragon 2 entered service in 2016.Specification: Submerged Dragon 3. Submerged Dragon 3 is a development of Submerged Dragon 2, and has since been deployed in various Chinese research missions. The general designer is the same general designer of Submerged Dragon 2, Mr. Liu Jian (刘健)and the deputy general designer is Mr. Xu Yijun (许以军). Externally, Submerged Dragon looks identical to its predecessor Submerged Dragon 2, and it is an upgrade of Submerged  Dragon 2.Improvement includes replacing equipment with high power consumption on board Submerged Dragon 2 with equipment with lower power consumption with same performance on Submerged Dragon 3; replacing the imported foreign-built critical components of the navigational system on board Submerged Dragon 2 with domestic Chinese ones on Submerged Dragon 3; more efficient propulsion systems, better noise reduction and longer endurance achieved on Submerged Dragon 3 in comparison to Submerged Dragon 2.Like earlier Submerged Dragon 2, the original ranging sonar on board Submerged Dragon 1 is also replaced by a forward looking imaging sonar on Submerged Dragon 3, along with  other navigational systems, to help Submerged Dragon 3 to navigate in the valleys and ravines of seamounts, and trenches in seabed,and the sonar produces better image with higher resolution in comparison to that of Submerged Dragon 2.Submerged Dragon 3 entered service in 2019.Specification: