Quantum Slipstream Drive
From FEInfobase
The Quantum Slipstream Drive (QSD) generates a sustained subspace pulse designed to open and maintain a conduit through subspace strata. The Quantum Slipstream Drive allows starships to travel long distances at speeds well above the warp 10 barrier. The conduit is large enough for 2 medium sized Starfleet vessels to travel through with a ship equipped with the Quantum Slipstream Drive as long as they remain in it's subspace field.
The drive was named by Doctor Jacob Thatcher as the best way of describing the effect on a ship travelling within a conduit. The quantum mass of a ship is reduced to near zero allowing the molecules of the ship to quickly and easily pass through space with little or no resistance.
While Federation technology has advanced far enough to allow the development of the QSD there were still drawbacks with the technology. A Quantum Slipstream Drive requires massive power reserves to open a conduit, often a ship will have to charge capacitors to provide the first rush of power. Channeling through the Quantum Slipstream Drive, the deflector dish opens the initial conduit as the nacelles create the subspace field allowing the ship to be propelled at phenomenal speeds.
The only Starfleet vessel ever equipped with the Quantum Slipstream Drive was the Excalibur-class USS Excalibur which temporarily served in the Starfleet Rapid Response Task Force. Eventually it was reassigned to one of the few deep space re-exploration assignments. The Excalibur was officially made the fastest ship in the fleet.
Eventually the Quantum Slipstream Drive proved to be an overall failure due to it's cool down, power usage problems, and potential critical overloads to the ship. The Excalibur was brought back to Earth Spacedock to have it's Quantum Slipstream Drive dismantled and the ship was refitted with a more conventional warp drive. The Quantum Slipstream Drive did, however, help improve the new generation warp systems of some of the newest starship designs being produced by Starfleet; the Century class, Ark Royal class, and even the Excalibur class' new warp engines all saw improved efficiency and speed.