As a clarification: it seems to me that anti-gravs may not involve jet engines, as can be seen in some of the work, because. the operation of a jet engine, if I understand correctly, involves the use of the law of conservation of momentum (ie, movement occurs through "repulsion"). If there is anti-gravity, then, as it seems, by its action it should exclude the influence of any external forces on the body. It turns out that the law of momentum does not work and there is nothing and nothing to push off from. There remains another way of moving: from a state of isolation from external influences, turn off this isolation in different directions and for different forces. For example, a car can be "opened" to external pulling forces from the front (something like a well into which the body is sucked, but in the right direction and with the right force) and pushing forces from behind (the opposite of the previous version).