The alternate Constitution-class dates back to at least 2255 with the construction of the USS Enterprise in Riverside, Iowa on Earth. The design of the starship class markedly differed from its prime universe counterpart following the temporal incursion by Nero and the destruction of the USS Kelvin in 2233. (Star Trek)
Following its launch in 2258, the Constitution-class USS Enterprise served the United Federation of Planets in a variety of tasks, including survey missions and military operations. The class wasn't placed into long duration service until the Enterprise was assigned a five-year mission after 2259. (Star Trek Into Darkness)
In that year, a space dock manifest display graphic in the office of Admiral Christopher Pike included two Constitution-class icons identified as AF and VH-5. (Star Trek Into Darkness, production art)
In 2263 a second Constitution-class vessel, the USS Enterprise-A was under construction at Starbase Yorktown. That same year, the Enterprise itself was destroyed by Krall and his Swarm ships in the Battle of Altamid. After Krall's defeat, the Enterprise-A was finished and given to the crew of the original Enterprise as their new starship. (Star Trek Beyond)
The Constitution-class starship followed the traditional saucer section-engineering section-warp nacelle layout common to most Starfleet vessels, but dwarfed in size many starship classes in service alongside it. Where the prime universe Constitution-class of the same period featured a similar, but geometrically simplified construction, the alternate Constitution-class displayed a more organic physical arrangement. The hull had iridescent plates and a subtle Aztec pattern. Escape pods could be launched from the port side of the neck. (Star Trek)
The uppermost section of the ship composed the primary hull - or the saucer section. The saucer section was joined to the engineering hull by a stout "neck" that terminated along the dorsal side of the engineering hull fore of the shuttlebay, which was able to hold at least twenty shuttlecraft despite being shorter than the ship's bow. By 2263, the ship had a longer and more narrow neck among other structural modifications made over the course of its service. (Star Trek Beyond)
The engineering hull was conical in shape, capped by the main deflector to the fore and the main shuttlebay to the aft. The shuttlebay 2 launch bay door was located forward of the main shuttlebay on the starboard side below the warp nacelle pylons. The deflector dish's center would open and close when entering and exiting warp. The shuttlebay and flight decks comprised a large portion of the engineering section as did main engineering and its related hardware. (Star Trek; Star Trek Into Darkness)
The ship's two warp nacelles were mounted by pylons to the port and starboard sides of the ship's engineering hull, each at a near-forty-five degree upward angle, fore of the ship's flight deck doors. The nacelles featured a flared housing around the Bussard collectors, which dimly glowed blue, and the aft section contained components that extended and retracted when entering or exiting warp. The uppermost section of the nacelles were parallel in height to the ship's bridge. The life support center of this class was located aft of the warp nacelles. (Star Trek Into Darkness)
Inside the Constitution-class, upper sections were predominantly white with polished black floors. A large, circular atrium connects corridors to walkways that allowed crew members to cross the lobby with a vertical view up to a dome at the top of the ship's primary hull. The lower decks progressively displayed less aesthetic design. Crewman workstations often had little personal space to work in. The engineering decks consisted of conduits, tanks, and catwalks spanning each section. Ladders located in corridors allowed crew members access to spaces above and below their current location. (Star Trek; Star Trek Into Darkness; Star Trek Beyond)
Command and control systemsEdit
The Constitution-class's primary command center, the main bridge, was located on top of the vessel's primary hull, on A Deck. From here, the commanding officer supervised the entire starship's operation from the command chair, located behind the helm and navigation consoles, and was flanked on all sides by stations controlling the vessel's primary functions. A large window augmented with computer displays served as a viewscreen, located at the fore of the bridge.
Piloting and navigation functions were carried out at the helm console, located in the center of the bridge. This console consisted of three main sections – navigation and ops stations and primary tactical control. Behind and flanking the captain's chair were two forward-facing workstations for a junior science officer (port) and a junior communications officer (starboard), supplemented by free-standing data screens. The senior science officer's and com officer's stations were located along the starboard back wall of the bridge. Numerous other stations occupied the walls of the bridge as well, generally populated by engineering division crew members to starboard and science division personnel to port.
All operations on the bridge and elsewhere aboard the Constitution-class vessel were performed on touch-screen consoles and displays. The ship's primary computer core was capable of being linked to cybernetic personnel for analysis. (Star Trek; Star Trek Into Darkness; Star Trek Beyond)
By the year 2263, two computer console stations at the starboard and port sides of the viewscreen were replaced with access hatches to Kelvin pods - single man escape pods. These hatches provided easy egress to command crew during emergency evacuation situations. (Star Trek Beyond)
The Constitution-class cruiser was outfitted with a single twin-exhaust impulse drive unit mounted at the back of the saucer section where the primary and engineering hulls join. The saucer section of the ship was also fitted with numerous ventral RCS thrusters which could operate in space, in a planetary atmosphere and - if required - within a planet's ocean. (Star Trek; Star Trek Into Darkness)
Warp propulsion was powered by the warp core that comprised of multiple warp reactors. Energy from the matter/antimatter intermix was fed to the two warp nacelles. When going to warp, the impulse reactors would deactivate and the tail of the warp nacelles would expand when the ship jumped to warp speed. The multiple warp reactors could be ejected in cases of extreme emergency.
Unlike the ship's prime reality counterpart, both impulse and warp drive were regulated from the bridge, with engineering serving as monitoring and maintenance mid-flight. If not disengaged, external inertial dampeners will negate acceleration to warp velocity. (Star Trek)
By 2259, the several smaller reactors were replaced by one large warp core that was housed in a large hemispherical containment unit, with a large electrical coupler at its center allowing distribution of power to the rest of the ship. The warp core was isolated from the rest of engineering by several radiation doors. Sometime later, following nearly a year of repair, a wider, single-exhaust impulse engine was installed on the Enterprise. The fins on the warp nacelles were also refitted with new sets of warp drive components. (Star Trek Into Darkness)
Further modifications were made before 2263, replacing the warp nacelles with similar but smaller, thinner units and the nacelle pylons were elongated and swept back away from the primary hull. (Star Trek Beyond)
Main engineering was aesthetically bare-bones. The entire section was occupied by and controlled machinery required to keep the ship operating. Pipes, conduits, and tanks typically occupied the floor while catwalks spanned the space overhead. The original warp core design consisted of multiple dilithium crystal chambers, which were replaced a year later with a single warp core unit. (Star Trek; Star Trek Into Darkness)
The saucer section of the Constitution-class was armed with six phaser banks, all with twin phaser turrets. Each of the twelve ball-turrets was capable of emitting a rapid fire barrage of phaser blasts. The banks were located on the dorsal and ventral sides of the saucer section. The phasers could be used for assault on an enemy ship or as point defense against enemy torpedoes. (Star Trek)
Following the refit of the Enterprise in 2259, the ship was later received additional phaser banks on both ventral and dorsal sides of the saucer section in total number twelve phaser banks. (Star Trek Beyond)
The torpedo bay and main forward torpedo launcher were located on the flared section of the neck connecting the primary hull and the secondary hull, and at least twelve photon torpedoes could be loaded simultaneously into torpedo tubes. The torpedoes could be fired rapidly in a barrage from the launcher. The ventral aft torpedo launcher was located at the bottom midsection of the secondary hull. (Star Trek)
A weapons bay was located on the deck of the engineering section with large broadside torpedo tubes on both sides of the secondary hull along the longitudinal axis. These tubes were capable of being loaded with the larger new advanced long-range torpedoes developed by Section 31 of Starfleet in preparations for a war with the Klingon Empire. After the Enterprise was repaired, the weapons bay and torpedo tubes were seemingly removed. (Star Trek Into Darkness)
In 2259, the Constitution-class was equipped with metaphysic shields as a part of its defensive array. The shield strength of the ship was indicated by diburnium-osmium levels that gave the ship protection from threats, such as phaser and photon torpedo fire from enemy targets. Shielding was divided into bow and aft deflectors. (Star Trek Into Darkness, display graphic )
There was at least one armory located on board the Constitution-class, accessible from a standard corridor. This area provided access to numerous phasers and phaser rifles of varying configurations, attached to the bulkhead for access by security personnel. (Star Trek Beyond)
A large brig was located aboard Constitution-class vessels during the 2250s. An open, circular section accessible by two corridors, the brig featured at least two cells protected by transparent aluminum. Two guard stations were positioned at slightly sunken computer consoles located at the center of the compartment. The cells themselves were characterized by two benches on either side, but little else in the way of accommodations. (Star Trek Into Darkness)
A relay room located behind the deflector dish, this area supported the communications station on the bridge as well as certain engineering functions. Crew members sat and stood at various stations set against two rows of large, cylindrically-shaped tanks. (Star Trek)
A warp power manual override switch was located in a console in this area. (Star Trek Into Darkness)
The medical facility was known as "med bay" and was located within the saucer section of the ship. The med bay was characterized by a blue and orange color scheme and featured a lab area and numerous biobeds able to accommodate more than a dozen patients. The med bay was accessible from both a standard corridor and a direct turbolift. (Star Trek; Star Trek Into Darkness)
The transporter room aboard the Constitution-class occupied a corridor room of the saucer section. The back of the room was a circular alcove containing the transporter pad. The blue steps of the transporter glowed red when in use. The transporter control system was located just inside the room's entry, and was shielded from the transporter pad by either a glass or transparent aluminum wall. The control system was illuminated by lamps attached to the control board by flexible necks.
Transporter target lock was attained by using a joystick control to lock onto the target(s) designated for transport. Operation of the transporters typically required that the target not move, relative to its own surroundings, before it could be dematerialized. The system could be used to lock on to a moving target and negate the target's momentum upon rematerialization, but using the system in such a way required a highly skilled operator. The transporter chief typically wore a miniature heads-up display in front of the left eye. (Star Trek; Star Trek Into Darkness; Star Trek Beyond)
There was at least one bar on board the Constitution-class. A small view port was located here with an adjacent table and chairs. Across the room featured additional seating. (Star Trek Beyond)
The archive vault was a section devoted to the storage and study of artifacts was located aboard Constitution-class starships during the 2260s. This area was distinguished by curved bulkheads with numerous slots and shelves for storage. A computer station was located in the center of the section for scanning and cataloging of items before they were securely stowed. (Star Trek Beyond)
Background information Edit
For the Enterprise depicted in the "Kelvin Timeline" films Star Trek, Star Trek Into Darkness and Star Trek Beyond the Constitution-class was designed by Ryan Church, based on the original Constitution-class design, which was conceived by Matt Jefferies. On the Starships Blu-ray featurette, it is acknowledged that the redesign has elements of both previous versions of the Constitution-class Enterprise, from Star Trek: The Original Series and the first six Star Trek films respectively. The redesign was also inspired by the sleekness of a hot rod car. For Star Trek Into Darkness, Industrial Light & Magic digitally generated the Constitution-class model using a new CGI renderer – Solid Angle Arnold, in conjunction with the Katana lighting tool released by computer graphics and visual effects software developer The Foundry. (Cinefex, No. 134, p. 72)
For its appearance in Star Trek Beyond, the digital model of the Enterprise was passed from ILM to Double Negative which handled the bulk of the visual effects for that film. Using the model from ILM as a basis, which included upgrades given to the model after its "refit" at the conclusion of Star Trek Into Darkness, Double Negative built an entirely new model under the guidance of director Justin Lin. This was done because although the original intent had been to modify the ILM model, the ILM model did not carry the internal detail needed for the lengthy sequence involving the destruction of the Enterprise. Rhys Salcombe, Double Negative's build lead for the Enterprise, stated: "We knew the neck had to break, the pylons had to break... The INTO DARKNESS model of the Enterprise was not built to be destroyed... We could have made some new elements and appended them to the original model, but because it was pretty much the whole thing, it was simpler to make a whole new model." According to VFX Supervisor Peter Chiang: "There's a big story point about the vulnerability of the ship. Justin wanted it to resemble a little more the original 1966 Enterprise, where the nacelles and neck were quite thin." 
The bridge, upper corridors and turbolift, transporter room, and sickbay of the revised Constitution-class were built as sets at Paramount Pictures. According to Production Designer Scott Chambliss and others on the Star Trek film's Blu-ray and Star Trek - The Art of the Film, the ship's white upper levels were inspired by Pierre Cardin's architecture, an approach which evidently continued to the brig in the sequel. Noted Roger Guyett, "We had somehow managed to negotiate the dangerous waters of redesigning the Enterprise – adding detail and making it feel more modern." Whereas re-envisioning the Constitution-class for the film Star Trek represented a major design challenge, the class remained relatively unaltered in Into Darkness, though the filmmakers of the latter movie decided to explore the design in more detail. "We used the same sets, redressed and updated," noted Visual Effects Producer Ron Ames. (Cinefex, No. 134, p. 72)
A new addition to the Enterprise sets was a large, circular atrium connecting the traditional corridor sets with a vertical view up and down the height of the ship provided by CGI. This atrium - called "turbo plaza" or "circulation lobby" in various production and behind-the-scenes materials - was intended to be located in the primary hull of the Enterprise in Into Darkness, however appears to be located in the secondary hull for its appearance in Star Trek Beyond. (Cinefex, No. 134, p. 72)
The more industrial lower levels and engineering section of the ship were filmed at the Budweiser Brewery in Van Nuys, California for Star Trek and Star Trek Into Darkness. The National Ignition Facility in Livermore, California stood in for the Enterprise warp core in Star Trek Into Darkness.  Though the filmmakers had explored designing sets for these sections, it was ultimately decided to film on location because they lacked the money.
Production Designer Thomas E. Sanders took over Scott Chambliss' duties on Star Trek Beyond, overseeing the reconstruction of the Enterprise interior at Vancouver Film Studios in Vancouver, British Columbia. A departure from the previous two productions, the bridge set was built on a shaker deck, allowing three-inches of movement in all directions and negating the need to have the actors fake impacts and shakes. (Cinefex, No. 148)
To simulate the destruction of the Enterprise, corridor sets and the "manual release room" were constructed on gimbals, allowing these locations to roll. Other locations aboard the Enterprise were built with the help of digital set extensions created by Atomic Fiction, these locations included sections of engineering and the torpedo bay. ()
The ship's dedication plaque lists the Enterprise as "Starship class", the same as its prime universe counterpart, while the ship's dossier on the official movie website identifies the Enterprise as a Constitution-class heavy cruiser.  The Enterprise is canonically identified as a Constitution-class starship in a viewscreen graphic from Star Trek Into Darkness, seen on the main bridge of the USS Vengeance.  The website also noted that she is being "held in Beta Testing Ward 956 – approved for combat." The maximum speed of the Enterprise is given as warp 8.
Co-writer Roberto Orci explained the logic of having the Enterprise being built on Earth rather than in space, noting that components of the ship can be built on Earth and assembled anywhere and that the Enterprise is not "some flimsy yacht that has to be delicately treated and assembled." He also feels that it makes more sense to construct the ship within a natural gravity well, rather than an area that would require an artificial gravity field.  Orci made these comments after a teaser trailer that was released prior to the film included footage, unseen in the movie itself, that showed the Enterprise under construction and being welded upon.
According to the Enterprise Tour and the "Starfleet Vessel Simulator" bonus feature, which was available on a Blu-ray Disc, the crew size of the Constitution-class was 1,100. According to the two sources, the internal configuration was as follows:
The primary hull housed the main bridge on the A deck, the ship's crew quarters were on D and E decks, F deck hosted the transporter room, and the sickbay was located on G deck. The primary hull also included the impulse drive and the science laboratories. The section was protected by phaser turrets on the ventral and dorsal sides. On the main bridge, there were fourteen seated crew positions. Several escape pods were also located in the section.
The secondary hull housed the ship's engineering systems on N and O decks and the hangar deck, capable of housing sixteen shuttlecraft is on R deck. The secondary hull also housed the main torpedo launcher, navigational deflector, and living and work spaces for the engineers. This section was protected by phaser turrets, a forward-facing main torpedo launcher on the neck pylon, and an aft-facing torpedo launcher located on the ventral side of the hull in a recessed alcove. Several escape pods were located in this section, with a majority of them being in the neck pylon. There was a tractor beam located at the rear of the ship which assisted shuttles during landing into the hangar deck.
In both sections, there were corridors and turbolifts. Corridors were equipped with communication terminals, safety features designed to keep the crew alive during emergencies, and emergency power supplies. There were access panels adjacent to doors that could restrict access to a compartment. There were passenger and freight turbolifts on the ship.
The warp nacelles housed the ship's bussard collectors, field coils, and warp coils. The collectors captured interstellar hydrogen via an electromagnetic field and converted the gas into fuel for the ship by a nuclear fission process. The field coils transmited subspace emissions that could be used for the sensor and communication systems. Plasma gases that were generated by the warp coils were expelled by exhaust ports located at the rear of each nacelle.
If the alternate reality Constitution class is the same size as it's prime reality counterpart, then it would mean it would be between 289 - 305 meters long depending on the configuration.
Before the release of Star Trek on Blu-ray, there were several conflicting, early, behind-the-scenes accounts regarding the scale of the Constitution-class starship.
- 1,200 meters: On 10 September 2007, a metric size chart depicted the ship to be 1,200 meters in length (3,937 feet). This early chart was reproduced for Star Trek - The Art of the Film (p. 145).
- 1,524 – 914.4 meters: In October 2007, the size of the Enterprise was still very much undefined. According to Star Trek illustrator John Eaves, at that time, it was considered to be somewhere between 3,000 and 5,000 feet (914.4 to 1,524 meters).  
- 914.4 meters: On 1 May 2009, a Post Magazine article entitled Star Trek Returns – which included an interview with Russell Earl, the co-VFX supervisor of Star Trek – cited the ship as being 3,000 feet in length (914.4 meters). 
- 762 meters: On 14 January 2008, an Industrial Light & Magic size chart of the Enterprise depicted the ship to be 2,500 feet (762 meters) in length. Alex Jaeger shows this chart in the Starships bonus feature on the Star Trek Blu-ray release. Before the release of the Blu-ray (on his blog), Jaeger had quoted the same figure from an unspecified early chart, adding that the size may have later been somewhat reduced.  Experience the Enterprise also used these dimensions: length: 2,500 feet (762 meters), saucer diameter: 1,100 feet (335.3 meters) and height: 625 feet (190.5 meters).  The USS Enterprise-A is also stated to be this size. 
- 725.35 meters: In November 2009, when Star Trek was released on Blu-ray, the length of the ship as 2,379.75 feet (725.35 meters) was a more prominently portrayed figure in the "Starships" bonus feature. It was also the size given in Star Trek - The Art of the Film (p. 160, Note 4). Gizmodo blog writer Jesus Diaz was the first to reveal this number, citing his source as being "David B." of Bad Robot Productions.  Bob Plant of Round 2 Models provided exactly the same figure, saying it was specified by the licensor of their planned model kit, who in turn had obtained it from ILM.  "My gosh, yes – JJ did make the ship that big. According to our (very reliable) source, the 'actual' size of the ship is 2,379.75 feet long. It’s a whopper. A 1/2500-scale kit would put the assembled model at about 11.5″ inches long, which is just right for standard size packaging."  In a separate interview, Plant also asked Enterprise designer Ryan Church, who said that he was unable to address the issue of the changed size (compared to that of the original series Enterprise) and that ILM or J.J. Abrams could probably better answer the question. .
- 718.4 meters: On 26 May 2009, in an article in CG Society on ILM's visual effects work for the film Star Trek, the length of the ship was stated to be 2,357 feet (718.4 meters). "One challenge was to sell the weight and scale of the ships that ranged from a 30 foot shuttle to the new Enterprise at 2,357 feet long, to the nemesis ship, the Narada, five miles long." 
- 609.6 meters: On 13 May 2009, in an interview for Studio Daily, ILM model supervisor Bruce Holcomb stated that the ship was 2,000 feet in length (609.6 meters). 
- 365.8 meters: In July 2009, in the article on Star Trek in Cinefex #118, it was noted that "the reconfigured ship was a larger vessel than previous manifestations — approximately 1,200-feet-long (365.8 meters) compared to the 947-foot ship (288.6 meters) of the original series." The statement is immediately followed by a quote from Visual Effects Art Director Alex Jaeger: "Once we got the ship built and started putting it in environments, it felt too small. The shuttle bay gave us a clear relative scale – shuttlecraft initially appeared much bigger than we had imagined – so we bumped up the Enterprise scale, which gave her a grander feel and allowed us to include more detail."
- 294 meters: In May 2013, a 1:500 scale model was released by Revell of the USS Enterprise. The model was 588 millimeters long. This equals to a length of 294 meters or 965 feet. 
The video game Star Trek D-A-C features various named Constitution-class ships. According to the game, the ships could also be armed with quantum torpedoes in the late-2250s. According to the mobile phone video game, Star Trek: The Mobile Game, the Enterprise was equipped with a massively powerful phase cannon capable of slicing through and destroying multiple starships.
- Primary hull: Computer Core P/S, Impulse Reaction System, Junior Officers Quarters, Lower Sensor, Main Bridge, Main Sickbay
- Secondary hull: Antimatter Fill Port, Battle Bridge, Cargo Bay Aft, Cargo Conveyor, Eng Computer Core, Main Engineering, Main Shuttle Bay, Photon Torpedo Launcher bow and aft, Primary Nav Deflector, Tractor Beam Emitter, Warp Reactor core
- Warp Nacelles: Field Geometry Sensor, Subspace Field Coil System
The Constitution-class appears in the game Star Trek Online starting with the third expansion series, Agents of Yesterday. Obtainable in the Kelvin Timeline Lockbox, these ships are classified as the "Kelvin Timeline Heavy Command Cruiser". According to the information on the package holding the ship, they were built in the main universe due to incursions made by the Na'kuhl and the Sphere-Builders, allowing them to see into alternate reality and realized that the technology of that timeline, despite a distance of just over 150 years, was similar to those in the year 2410. The ship has a number of skins, including one that allows it to mimic the original Constituion-class ships. The various warp cores used in the original configuration of the Enterprise were reclassified as auxiliary warp cores as part of the console "Auxiliary Ejection Assembly", which comes with the ship, allowing players to mimic the stunt Scotty does to get the Enterprise away from the Singularity caused by the Jellyfish's detonation. In terms of size, the Constitution-class is shown to be larger than a Galaxy-class (at 624.5 meters) yet smaller than the Odyssey class (β) (at 1,062 meters) which would put it closer to the ILM chart or the Blu-Ray feature numbers.