The K'T'Inga class battle cruiser was fielded by the Klingons during the 2270's to replace the D7 class as the Klingon's premiere combat vessel. The Klingon intelligence service had learned in 2263 that Starfleet was soon to engage on a major rebuild of the Miranda and Constitution class ships which would, among other things, equip them with the latest weapon and propulsion technology. Since the Miranda class had always been the approximate equal of the D7 one-on-one, and the Constitution had always been considered somewhat superior, the prospect of these ships becoming significantly more powerful was not one the Klingons welcomed.
The Klingon high command judged that developing and building an entirely new class of battle cruiser would take at least five to ten years, leaving nearly a decade when they would be vulnerable to attack. It was therefore decided that the new vessel would be based around the hull of a standard D7, which after more than a century of service was one of the most well proven designs in the history of any military force. Although the K'T'Inga is therefore almsot a wholly new ship internally, externally it bears a close resemblance to the D7 refit. The major external differences lie in the hull detailing; the clean lines of the D7 refit have been lost in the K'T'Inga in favour of a hull more reminiscent of the original D7.
The Armament of the K'T'Inga was upgraded throughout. A new heavier model torpedo was installed, cutting the number of torpedoes carried from 260 to 230. A Mark 10 disrupter cannon was mounted directly above each torpedo tube. The Mark 7 disrupters of the D-7 were replaced with Mark 8 models, of which an extra pair was worked in to the design. A higher power warp core and new nacelle design allowed a higher top speed and greater efficiency for longer range across all flight regimes.
The first of the K'T'Inga class was launched in 2269; by the time the USS Enterprise was due to completed her refit in 2271 - the first Constitution to complete this procedure - there were six K'T'Inga class vessels in service. Records of the time indicate that the Klingon High Command seriously considered launching an offensive against the Federation at this point; General Melkarr proposed sending two major attacks into Federation space, one headed for Earth and the other for Vulcan. Each attack would comprise thirty ships, twenty seven D-7s led by three of the K'T'Inga class. These forces were actually assembled while the council debated the matter, but before a decision was made reports reached the High Command of a large energy cloud penetrating Klingon space. The K'T'Ingas from the Earth attack fleet were dispatched to investigate, but as soon as they intercepted the cloud all three were destroyed by plasma weapons from within by the entity which was at the heart of the cloud. The loss of half of their newest battle cruiser fleet in the space of minutes threw the high command into a near panic; the attack on the Federation was postponed and the fleet was ordered to escort the anomaly out of their space from a safe distance. When the USS Enterprise apparently succeeded in destroying the intruder, the Klingons concluded that the new Constitution design was far more powerful than they had assumed and cancelled the attack altogether. By the time the truth behind the V'ger incident emerged, Starfleet had upgraded its fleet sufficiently to make a new attack unfeasible in any event.
Light Cruiser - Refit, late model
By the 2290s the K'T'Inga was well established as the mainstay of the Klingon fleet, but the last twenty years had allowed some progress in ship design and the Klingons decided to field a new version of the ship with updated systems. Changes concentrated around the engines, with a new nacelle design allowing higher top speed, but various other changes were also introduced throughout the ship.
The most notable member of this class is Kronos One, the Klingon chancellor's personal transport vessel. This ship met with the USS Enterprise under the command of Captain Kirk in 2293 during Gorkon's peace mission to Earth. The Klingon vessel was subsequently attacked by a cloaked Bird of Prey during Gorkon's assassination. The ship survived the attack and returned to Klingon space with Captain Kirk and Doctor McCoy on board.
Versions of this ship have remained in service with the Klingons until the 2370s - several examples took part in the Klingon assault on DS9 in 2372. By this time the forward torpedo launcher had been replaced with a disruptor cannon.
Source: Daystrom Institute Technical Library
Cheers Thorgrimm 
