There has been speculation of mysterious US aircraft that is capable of something very similar to alien technology. Even there is a patent over it.
TR-3B Black Manta or TR-3A or Astra is a highly classified black triangular aircraft that is explained like this in the patent:
"A spacecraft having a triangular hull with vertical electrostatic line charger on each corner that produce a horizontal electric field parallel to the sides of the hull."
This patent is found on Google Patents with the inventor's name as John St. Clair.
About the construction of aircraft has been explained as follows:
The triangular hull is in the form of complete equilateral triangle. There are two copper plates attached on opposite vertical sides at each of the three corners of the hull. In order to charge the copper plates corners to a high voltage, an electrostatic generator is use.
Beyond this, there has been claims that this spacecraft uses nuclear power to rotate highly pressurized mercury to produce plasma and ultimately gravitational field. This is how anti-gravity is being claimed to be created.

The sightings of similar objects to TR-3B has been confirmed in entire world from Gulf War to Nevada and California. Even British Government confirmed the sightings of it as flying black triangle.
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