Star Trek: 10 Secrets About The USS Protostar You Need To Know
2. Starring Role
The Engineering section or, more specifically, the warp core(s) is described by Ben Hibon as the "beating heart of the ship". Throughout the Protostar the decks are filled with technology and the interior design generated from Engineering and expanded out from that point.
The whole ship is effectively built around the three warp cores, emphasised with the hidden third nacelle which emerges from the hull to propel the Protostar at previously unseen speeds.
The reason it has two standard warp cores is because the protodrive needs such an immense amount of power to run. In fact, as Aaron J Waltke notes; "The second warp core is used to power the protostar containment field while in operation".
There was no definite line on just how fast the new drive was. As Aaron Waltke says, "we decided it was faster than quantum slipstream, but it had longer cooldown time between protowarps".
In the series DVD extras, the Hagemans reflect on the fact that the Enterprise was a gorgeous ship but really didn't "do" anything - which is how the hidden nacelle and the descending engines came to be part of the design, making the ship more interactive.
Additional note, this is the first time a starship is named after a key feature of the vessel itself!