>(HAUC), which can function as a submersible craft capable of extreme underwater speeds (lack of water-skin friction) Chinese advancement in frictionless super

>(HAUC), which can function as a submersible craft capable of extreme underwater speeds (lack of water-skin friction) Chinese advancement in frictionless supercavitating submarines are already well known[1]. But claiming that they have the capability to do so with EM propulsion is something new. What's more bewildering to me is that the patent fiasco surround this. AFAIK state of the art defence tech rarely gets through patent system for obvious reasons, TIL that U.S. Patent system has a way to file secret patents and even that wasn't used in this case. Not sure whether they filed this patent with PCT (Patent Cooperation Treaty), then they would be eligible to submit this patent application for review in other countries as well. [1]: https://www.popsci.com/article/technology/chinas-future-submarine-could-go-speed-sound/ https://www.popsci.com/article/technology/chinas-future-subm...