Currently to date there are 6 Federation Starships that make up the historic lineage of the Starship Enterprise. These are:.
The original Enterprise, registry number NCC 1701, was a Constitution class ship. It was launched in 2245 from the San Francisco Yards orbiting Earth, originally under the command of Captain Robert April, then Christopher Pike moved up to the centre chair, and then Captain James T. Kirk.
The Enterprise became legendary under the command of Captain James Tiberius Kirk, who commanded her from 2264, up until 2269 for his first five year mission.
This ship was refitted in 2270, where every major system was upgraded, a new bridge module was inserted, and the warp nacelles were replaced. This ship was destroyed in 2285 by Captain Kirk, who was preventing it from falling into the hands of the Kingons during a rescue mission to recover the body of his friend and collegue, Spock.
It measured an impressive 289 metres in length.
The Enterprise-A, registry number NCC 1701-A, was also a Constitution class ship. This one was launched on Stardate: 8442.5 (2286) from the San Francisco Fleet Yards, Earth. Once again this legendary named vessel was placed under the command of Captain James T. Kirk.
One of it's most historic missions involved the success of the Khitomer Peace Conference, where the assassination of Chancellor Azetbur was averted, with the assistance of the USS Excelsior, under the Command of Captain Sulu.
This vessel was larger than it's predecessor, measuring 305 metres in length and had redesigned warp nacelles
The Enterprise-B, registry number NCC 1701-B, was an Excelsior class ship. It was launched on Stardate: 9715.5 (2294) under the command of Captain John Harriman, and her first mission was a simple shake down cruise, as Harriman put it, 'Just a quick run around the block, out to Pluto and back home again'.
However, things did not go exactly to plan, and the ship responded to a distress call from the SS Lakul which was transporting El Aurien refugess to Earth, and was caught in an energy ribbon called the Nexus. It was during this mission that Captain Kirk, who was attending the launching ceremony was lost, when the ribbon struck Engineering where Kirk was trying to reroute power to the deflector grid to break the ship free before it was destroyed. Kirk was found missing, and with the whole in the hull of the ship, presumed dead.
Again, this vessel was larger than her predecessor at 467 metres in length
The Enterprise-C, registry number NCC 1701-C, was an Ambassador Class ship. She was placed under the command of Captain Rachel Garrett.
She was presumed destroyed near Narendra III in 2344, when Captain Garrett responded to a distress call from the Klingon outpost which was under attack from the Romulans. However the Enterprises' involvement and help towards the Klingons, helped prevent the Federation and Empire plunging into a bitter war.
Again, the Ambassador class craft was larger than her predecessor, measuring in at 526 metres in length.
The Enterprise-D, registry number NCC 1701-D, was a Galaxy Class ship. She was launched in 2363 from the Utopia Planitia Fleet Yards orbiting Mars. She was placed under the command of Captain Jean-Luc Picard. Her mission was one of deep space exploration and diplomacy. Like her predessessors, this Enterprise was the flagship of the Federation.
It's overall length was 641 metres, it had a cruising speed of warp 9.2, a maximum warp of 9.6 and 42 decks.
She was finally destroyed in 2371 at Veridiian III, where the saucer section crash landed, after being knocked into the planet's orbit whilst escaping the blast from it's exploding stardrive section. Although the saucer survived the crash, she was not recoverable.
In the final episode of The Next Generation, 'All Good Things...', we saw another version of the Enterprise-D some 25 years into the future. She was under the command of Admiral Riker. The main differences between this one, and the one that was destroyed on Veridiian III were the appearance of 3 warp nacelles, and a very powerful phaser rifle. As the Enterprise was destroyed in 2371, this ship has not existed in the current timeline, but is included here for completeness.
The most recent incarnation of the legendary name, is the Enterprise-E, registry number, NCC 1701-E. This vessel is a Sovereign Class ship. Like the ships that went before her, this incarnation of the Enterprise remains the Flagship of the Federation. It was launched on Stardate: 49827.5 (2372), from the San Francisco Yards, Earth, under the command of Captain Jean-Luc Picard and is currently the most advanced ship in the fleet.
It's overall length is 685 metres, and she has 24 decks. Her armaments include Quantum torpedos