[Jack Hydrazine]

Black triangle aircraft/anti-gravity craft have been reported since at least the early 1990s.

[GOPJ]

I saw one in the late 80’s...

[Prospero]

Try the mid 1970's, and decades earlier if you want to grasp the material science advances over the last 60 years.

And there's nothing "anti-gravity" about this technology. It's what Hermann Oberth casually referred to as "ze electric space ship," repelling against Earth's magnetic field.

It's always looked good "on paper," but impractical, driving the development of high-temperature conductive and light-weight materials, along with a lot of other technologies.

[Lee'sGhost]

But those were just unsubstantiated rumors. This is real.