The principle of motion of a flying saucer can be described as repulsion, in which one body gives acceleration to another, and receiving opposition from the force of inertia of another body, accelerates itself. I have not found any explanation of what repulsion is. Perhaps this is a jet propulsion.
Consider the engine as a system of two interconnected bodies that repel and attract each other. At the same time, their common center of mass remains in place. If during their repulsion a force acts on one of the bodies to resist its movement, then the other body, according to the law of conservation of energy, moves further. And the common center of mass of two bodies shifts. Thus, the system comes into motion. Thus, it is repelled by the force resisting the movement of one of the bodies.
In order to obtain this resistance force in the air, we make one of the bodies in the shape of a sphere so that it is streamlined, and the second is given a plate shape so that it experiences maximum air resistance during movement.
When these 2 bodies repel each other in the air, the plate gets more resistance and moves a shorter distance, and the ball gets less resistance and moves a greater distance. And the whole system moves. If the bodies are pulled back at the same speed, then we get a car with an umbrella, and the system returns to its original position.
But if the bodies are attracted with greater speed, then as a result of acceleration, their mass and kinetic energy becomes larger, the plate gets more air resistance. But at the same time, the plate transfers its energy to the air, and the air around the plate begins to move in the direction in which it pushed it. The movement of air by inertia continues even after the plate has ceased to push it. A wind is formed which pushes the plate like a sail. At this time, the plate is slowly attracted to the ball, creating a force directed against the wind. The energy of the plate, and the force that it creates in this case is less than that which it gave to the air by the previous action. As a result, the air flow drives the entire system. Thus, the original two-body system is repelled by the wind, exerting pressure on it from one side.
Similarly, this system works in space, starting from the solar wind, if the plate is a sail. Since the solar wind creates the sun, there is no need to create it. Due to the fact that the speed of the light wave is greater than the speed of the system, the light waves constantly put pressure on it from one side and it can keep pushing away from them until it reaches the speed of light. Perhaps, having pushed off from the light one last time, and not having received resistance to moving forward, it will exceed the speed of light as much as it can push off.