Type: Escort
Length: 170.68 m
Beam: 134.11 m
Draft: 30.10 m
Max. speed: warp 9.95
Armaments: 4 pulse phaser cannons
3 phaser beam emitters
2 forward quantum torpedo launchers
1 forward photon torpedo launcher
2 aft photon torpedo launchers

A Defiant-class starship is a heavily armored, limited-role Starfleet vessel developed at the Antares Fleet Yards in response to the Borg threat to the worlds of the Alpha and Beta Quadrants. The project was officially begun in 2366 by Starfleet's Advanced Starship Design Bureau (ASDB) under less then ideal conditions, as far as the accepted normal sequence of research, development, testing, and evaluation was concerned. Fortunately, a number of hardware innovations and design adaptations were already in the inventory and allowed for an acceptable level of reliability versus speed of systems integration and vehicle construction.

Defiant-class vessels are constructed of standard tritanium and duranium alloys and composites. The bridge has been submerged within a larger Deck 1 than was envisioned for the pathfinder vehicle, and the entire vessel has been shortened to four decks plus allowances for crawlways and cable trunks. The notched forward hull has been equipped with a detachable pod consisting of the vehicle's main sensor and navigational deflector, airlock module, and a last-resort matter-antimatter warhead. The warp nacelles have been brought inboard to a minimum safe distance for field EM, and all EPS weapon-power conduits have been truncated to provide a nearly zero lag time between activation signal and beam launch.

All protected internal systems that require access to the vessel exterior are equipped with articulated or jettisonable hull plates, so that most of the familiar structures are hidden from view, including shuttlebay doors, docking ports, lifeboats, impulse vents, and consumables resupply connectors. An integral set of ventral docking clamps and landing pads had been designed into Defiant for possible ditching operations as well as for recoverable planetary landings. No practical demonstration has been attempted, though simulations indicate that if the impulse and reaction control thrusters are fully operational, a successful liftoff to orbital velocity is likely.

The U.S.S. Defiant NX-74205 was the prototype vessel for Starfleet's Defiant-class starships. It was Starfleet's first true warship and had no provision for families or diplomatic missions, no science labs, no holodecks, or any of the other comforts of home. It was a heavily armored, stripped-down vessel that was created as a first strike vehicle for use in war, and incorporated the latest in Starfleet weaponry and defensive technology. As befitted its role, the U.S.S. Defiant was considerably smaller than most Federation starships. It had a normal operational crew of 40 people, but could accommodate up to 192 in emergencies. Work on the Defiant project began in 2366 after Starfleet was alerted to the threat of a Borg invasion. The ship was developed by Starfleet's Advanced Starship Design Bureau (ASDB) at the Antares Fleet Yards and at the Utopia Planitia Fleet Yards on Mars. It was still in the design stages when the Borg arrived in 2367. Even though the crew of the U.S.S. Enterprise NCC-1701-D defeated the Borg, Starfleet was sufficiently concerned about the danger of a second invasion attempt to continue work on the project.

Overall responsibility for the Defiant project rested with Admiral Batelle Toh, though a number of more junior officers were responsible for day-to-day operations. From 2367 to 2369, Commander Benjamin Sisko, a veteran of the Battle of Wolf 359, worked on the Defiant while he was stationed at the Utopia Planitia Fleet Yards on Mars. The Defiant project began with the selection of an existing spacecraft design that had just entered the initial systems-level review stage. No spaceframe had yet been constructed, and the hull shape was undergoing warp field interaction simulations. The study vehicle, designated NXP-2365WP/T, was being considered as a fast torpedo attack ship for high-warp penetrations of threat defenses. This Defiant pathfinder would have mounted six torpedo launchers, four in the primary hull and two in the engineering hull, capable of firing photon and quantum torpedoes at speeds up to Warp 9.982. When the Borg threat drove the redesign of the pathfinder vessel, it was decided to compact the platform with warp nacelles and other structures, which were pulled in closer to the engineering hull, minimizing the sensor cross-sectional area and vulnerable appendages. It was also deemed necessary to surround the hull with multilayer ablative armor, long considered unworkable for production starships. In its initial Borg-suppression role, the Defiant class would have produced as few as six custom-built copies. The mission of the Defiant did not change radically until it was out of the systems integration stage late in 2370 and into final hull reinforcing. Intelligence-gathering efforts had come upon the Jem'Hadar problem, and in the final year of spaceworthiness testing (2372), the NX-74205 was redirected to Deep Space 9 to become a mobile defensive platform with orders to defend the space station, the wormhole, and Bajor. Defiant was also tasked with patrol missions in the Bajor Sector and the Gamma Quadrant, engaging threat forces if necessary, as well as special covert assignments ordered by Starfleet Command.

Early on in its development the Defiant was regarded as a fast torpedo attack ship. Its designers planned to equip it with six torpedo launchers and a large complement of both photon and quantum torpedoes. However, as the Defiant project evolved, the ship was given more ambitious mission objectives. The Defiant's design was something of a departure for Starfleet; the development team took the decision to abandon the traditional Starfleet layout which placed the warp nacelles at the end of twin pylons and moved them in much closer to the main body. This reduced the size of the Defiant's profile, making the ship a much harder target to hit. In another important innovation, the designers gave their new ship multilayer ablative hull armor, which could resist repeated weapons fire. Under the ablative armor, the original hull of the NX-74205 prototype was constructed of a castrodium/neutromium composite. Due to difficulties inherent to the manufacturing of the exotic alloy neutromium, production-line vessels were chosen to be constructed with a modified duranium/tritanium composite augmented by synthetic castrodium alloy structural members, which makes the hull slightly more dense and less susceptible to impact damage then most other Federation starships. Considerable effort went into making the Defiant faster and more heavily armed than standard Starfleet vessels. It was equipped with both warp and impulse engines; by running a plasma conduit through the primary phaser coupling, the designers almost doubled the phaser power, and boosted the efficiency of the warp drive by 30 percent. Standard cruise speed was warp 7, and safe maximum warp speed was warp 9, though the Defiant was capable of exceeding that limit for short periods of time in an emergency. Indeed, Defiant's warp core rarely functioned at full capacity, because it was discovered that doing so endangered structural integrity. It wasn't until extensive field analysis and on-site development, by Commander Benjamin Sisko and Chief Miles O'Brien, had been conducted that the ship's propulsion and power systems could be run at design specifications.

Once the Defiant prototype had proven itself, Starfleet took the decision to put the Defiant-class into production. By the end of 2373, there were a significant number of Defiant-class ships in operation, and over the next two years they played a vital role in the Dominion war.

The U.S.S. Defiant NX-74205 was destroyed by a Breen ship in 2375. Another Defiant-class ship, the U.S.S. Sao Paulo, was assigned to Deep Space Nine on Stardate 52861. Given the U.S.S. Defiant's exceptional record under Captain Sisko's command the Chief of Starfleet Operations gave a special dispensation to change the ship's name to Defiant. On this ship, the shield generators were completely reconfigured so that it would not be affected by the Breen's energy-dampening weapon. This new Defiant played a distinguished role in the final battle with the Dominion at Cardassia Prime, and remains stationed at DS9.

A total of four pulse phaser cannon assemblies are located in forward-facing locations onboard Defiant-class vessels. The cannons are located above and below the nacelle root attachments on the main body on both port and starboard sides of the ship. Due to the ship's extreme maneuverability, yard engineers deemed it unnecessary to mount aft-facing cannons onboard vessels of this class. Computer simulations also indicated an unacceptable loss in phaser power performance due to increased strains on the power systems from the proposed aft-mounted cannons.

The development of the pulse phaser cannon applies a number of lessons learned at the Starfleet Tokyo R&D facility, where large, nearly flawless emitter crystals had been grown in ground-based microgravity chambers. The new crystals, combined with rapid-discharge EPS capacitance banks and high-speed beam-focusing coils, allowed the phaser discharge to be stored temporarily (up to 2.1 nanoseconds) within the coils and then released as a layered pulse structured something like an onion and is able to land a target contact that is more difficult to disperse than a standard phaser beam. Four pulse phasers are located above and below the nacelle root attachments on the main body.

Pulse phaser cannons store up their charge between 1.7 and 2.1 nanoseconds, resulting in an energy pulse more powerful then standard Type-X phaser emitters. Rapid fire of multiple bursts is accomplished through a direct EPS shunt from the warp reactor. If situations warrant, power can be routed from the impulse engines through a secondary plasma tap. For maximum effectiveness, all four cannons fire several bursts at the same time, resulting in a large amount of energy impacting a relatively small location. This tactic has been proven to pierce the shields of threat vessels without having to collapse the entire grid. Maximum energy output of a pulse phaser cannon is classified as of this date.

Pulse Phaser Range: Maximum effective range is 150,000 kilometers.

Earlier production line Defiant-class vessels have a total of four torpedo launchers, two forward and two aft. During the Dominion War, it was found that Defiant-class starships were better suited to engage in hostile encounters with their phaser cannons, and the awesome number of torpedo launchers only served to use up the relatively small stockpile that the ship could handle. As a result, the second and current production line of Defiants makes use of a total of three torpedo launchers, using a location underneath the bridge originally intended for tactical systems for a third shuttlebay.

On both variants, the aft launchers can be found just behind the aft landing struts and Shuttlebays 1 and 2. The first production line vessel's two launchers were located in the space between the warp engine housing and the detachable Warhead. The Defiant (UPRTD) retains the aft torpedo launchers and replaces the other two launchers with additional tactical and scientific sensor packages. The removal of the stockpile space and older targeting systems allowed for the addition of a third shuttlebay in this variant. The new single forward-facing launcher is located just below the main deflector at the fore of the ship in a location originally used for a variable-setting beam emitter.

Along with the Sovereign-class, Defiant-class vessels are the only starships in the fleet normally outfitted with the Mark Q-II Quantum Torpedoes. But like all Starfleet ships, the launchers onboard a Defiant are capable of firing standard photon torpedoes as well.

Payload: The uprated design is capable of carrying a maximum of 64 torpedoes, while the original design had a standard load-out of 96.

Range: Maximum effective range is 3,000,000 kilometers.

Being of a relatively new and unique design compared to other ships in Starfleet's inventory, it is somewhat surprising that the Defiant-class line of ships makes use of standard graviton polarity source generators, the design of which has not changed much in the past 70 years. Off the shelf generators used in Galaxy-class starships were heavily modified by the original yard engineers at Utopia Planitia to closer pack the twelve 32 MW sources found in each generator, allowing for an additional four sources to be added. Designed in response to the oncoming Borg threat in the 2270's, all ships of this class make use of automatically rotating shield nutations.

A Defiant makes use of a total of four shield generators located throughout the vehicle space frame. The forward-most generator is located along the vehicle centerline within the Warhead section, and is responsible for keeping it shielded in the event that it must separate from the ship. Two additional generators are located further within the hull from the warp nacelles, port and starboard, while the final generator is located on the centerline just above the main impulse engines and forward of the deuterium storage tanks on Deck 1.

Standard flight operations require that at least two generators be operational at any given moment. To simplify field manipulation, it is desired for two corresponding units to be online, meaning that the forward and aft units should be used in sync, or the port and starboard units. During high-impulse and warp flight, the generators are kept at their minimum output to deflect stray particles in the interstellar medium from impacting the ship and degrading the hull. Should conditions warrant, one generator is capable of protecting the entire space frame. At high levels of alert, all generators are brought online and create a multilayered graviton field around the ship. In combat situations, the field is typically within several meters of the hull, creating an oval shape. If required, the field can be extended outward to protect another vessel or object at the sacrifice of some protection.

With the addition of the warhead component aboard the Defiant-class, yet another radical departure has been made from Starfleet's standard policy concerning tactical operations. Designed as a single-use last-ditch explosive component, usage of the warhead weighs as heavily upon a ship's commanding officer as the possible order to initiate self-destruct.

Housed at the forward-most portion of the ship, the warhead contains the ship's main navigational deflector, forward torpedo launcher and magazine, forward airlocks, and dedicated impulse engines for independent powered flight. Access to this area is provided by two walkways on Decks 2 and 3 where miniaturized versions of the standard airlock provided sealable entry between the main vehicle and the warhead. Interior movement within the pod is provided by two ladders that run between decks. A dedicated control room is located on Deck 2 and allows for both user operated and automatic control of the Warhead.

Typically used when the vessel is totally disabled, it should be noted that once the warhead is launched it cannot be reattached to its parent craft without the assistance of a space station equipped to handle small starships. Once the order is given, the Warhead section is detached from the parent spaceframe by means of four explosive bolts that serve to provide the initial forward momentum for the pod to leave the ship before engaging its own engines. EPS power distribution lines and ODN hard lines between the two craft are designed to break apart at key points during the separation, and the EPS flow is cut off upstream to prevent spill-off. Once free from its parent, the warhead is capable of achieving .8 c and automatically arms all remaining torpedoes present in the launcher storage area. Computer projections indicate that the entire warhead vehicle will be destroyed in the resulting collision between it and its target. Due to space restrictions, no escape pods are present in the warhead section, meaning any crewmembers aboard tending to the vehicle will perish in the resulting explosion. Feasibility of using the warhead as an escape vessel during imminent parent vessel destruction is currently under consideration at the time of this writing.

Without its main deflector dish, the Defiant-class vessel is unable to engage at high warp. However, the three remaining defensive shield generators, under computer simulations, have been shown to be able to sufficiently shield the vessel at low warp speeds in the event of an escape after the warhead has been separated. These generators are also capable of shielding the ship after the forward generator is lost once the warhead separates.

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