Warp 2 barrier
From Memory Alpha, the free Star Trek reference
The warp 2 barrier was a warp barrier.
It was the limit of warp speed in the preliminary stages of warp technology (21st and 22nd centuries). It was not until the 2140s that a warp engine conceived at the Warp Five Complex by Henry Archer broke this barrier. Commanders A.G. Robinson and Jonathan Archer demonstrated this advanced warp engine in the second NX class prototype, the NX-Beta. (ENT: "First Flight")
