This node is fictional. Refer to Continental Class Space Battleships.
The discontinuity drive a/k/a "D generator" is what propels a Continental Class space battleship at faster-than-light speed. OK, it looks like faster-than-light from the outside resp. it would look like it if you could actually see the ship when in D drive; but nothing really moves faster than c.
An immense fat discus suspended directly in the ship's centre of mass, the D generator is more or less a huge resonator for gravitational waves. It generates a sequence of pulses that, when interacting with each other, plunge the ship into a small, spherical discontinuity that can, by modulating these pulses, move in relation to our own universe. The D drive is just a chambered structure without moving parts; it is fed gravitational energy by auxiliary engines through radial intake ports. As a side effect, it generates artificial gravity for the entire ship.
A Continental Class battleship's D generator measures over twenty metres in diameter, weighs more than 10,000 metric tonnes and can hurl the ship through space at a maximal virtual speed of 0.78 light years per ship day, which is respectable, but not really much.