Triangular spacecraft
https://patents.google.com/patent/US20060145019A1/en
UFO Triangle Mystery | Unidentified: Inside America's UFO Investigation (S2, E2) | Full Episode
The USAs Most Secret Plane — TR-3B Patent is Now in the Public Domain
https://theeventchronicle.com/secret-plane-tr-3b-patent/
What Is Behind The U.S. Navy’s ‘UFO’ Fusion Energy Patent?
https://www.forbes.com/sites/arielcohen/2021/02/08/what-is-behind-the-us-navys-ufo-fusion-energy-patent/?sh=29864bb24733