Didn't the USA black projects after WW2 discover this decades ago?
Actually, "anti-mavity" has been discovered many times....although anti-mavity is probably the wrong term to use.
T. Townsend Brown discovered it prior to WWII, and the Germans discovered it durning the 2nd WW (look up "the bell"). A great book to read about this subject is "The search for Zero Point" by Nick Cook. It's an easy read, and only a few hundred pages....