I'm still not finished working out Sdock specs for these ships, but here's some background:
The Klingon Empire, while a powerful military regime had never trully embraced modernization of fleet forces. Preferring brute numbers, force, and guile over technological sophistication, the Klingons have for centuries simply used the same hull frames, using a large number of upgrades and reftrofits to increase their combat capability.
Venerable designs such as the B'rel class Bird of Prey scout, K'Vort class cruiser, K'tinga class cruiser, and derivitives had been in service with the Klingons for over a century. The D6 lineage, in fact dating as far back to early contact between the Klingons and United Earth Starfleet, has been known to exist in some form for the last 400 years.
Despite this, the glaring weakness of using proven, yet somewhat outdated designs in large numbers began surfacing during the Dominion War. Being faced with the first trully technologically superior opponent in their history, the Klingons while fighting valiantly lost a great deal of starships to the Dominion, in no small part from over-agressive tactics, but also from the abdundance of older designs in the Klingon fleet.
In addition the lack of a trully centralised defense force lead to a large disparity between crew training and fleet organization that made both logistics and strategic operations more difficult than need be.
With the rise of Chancellor Martok to the Klingon head of state, the Klingon internal affairs have been undergoing a massive shift in power. The formerly corrupt and wasteful vying of powers between great houses has settled somewhat, many younger Klingons having served under Martok during the Dominion War, have begun seeing past the older ways of bringing honour merely to oneself or one's family, and have started cooperating with the Chancellor's plans of a more streamlined, deadlier defense force. In his own words, the new Klingon Empire would "Become a sharper, more deadly weapon than the clumsily large bludgeoning weapon of the past."
To this end, the Klingon Imperial Navy, was formed in short order centered around elements of the KDF. In addition to simply streamlining the Naval forces into a singular entity(clans still retained their own militia fleets, but were vastly under-cut), Martok began funding a large modernization program. While having the goal of simply creating a more modern and cohesive strategic force, the program also had a secondary objective of jump-starting the worn Klingon infrastructure and economy. A large influx of development funds to previously neglected technological development programs allowed the Klingons to create and maintain more safely and advancedly constructed stations, in addition to rebuilding infrastructure necessary to maintain, and create a large number of technologically sophistacted vessels.
Martok not being one to allow foolish pride to get in the way of the good of the Empire, and with the urging of Federation Ambassador Worf, a great deal of Federation assistance was also brought. The Klingons in turn having a large stockpile of raw resources, contributed to rebuilding Federation assets, while Federation advisors began helping the Klingons modernise their long-neglected non-military programs such as simple industry, and commerce.
And the design history for both ships:
Kron
Among the first holes the Klingons noted was within their fleet structure, was the lack of a true destroyer sized unit. Traditionally relying on the venerable(but old) Bird of Prey, the Klingons had long neglected to fill a size class within the 100,000-1,000,000 metric ton range.
The lack of such a ship proved to be devestating during the late stages of the war, when the Klingons had to fight un-supported. The lack of mid-sized destroyers such as the Sabre, Springfield, Steamrunner and Norways greatly reduced the effectiveness of their attack cruisers. Doing so made the Vor'cha class extremely vulnerable to more medium sized targets and indeed even smaller groups of massed Hideki's and Jem'Hadar attack craft. While B'rels were effective at interception, their relative lack of size and sheer lack of concentrated firepower in the form of torpedoes made them inferior platforms for screening. While K'tingas were available at this size class, their older nature made them unsuited for fast screening, while K'vort class also shared the problem, in addition to their limited weapon arcs in comparasion to their agility.
Thus design was focused on a destroyer classification ship. The original specifications called for a ship approximately 190 meters long, with a displacement of approximately 160,000 metric tons. It was to be essentially a Klingon rebuild of the Sabre class, incorporating as many advances as the Klingons possibly could. Designated Project 519-Ko, it was given the highest priority of any ship class in the Empire.
However design snags begun to hit this project as early as it's inception phase in 2376. While Klingons excelled at essentially doing more with less, the expectations placed upon the design had proved too great. The generators available to even the Dominion had proved inadequate to drive the new Class IX disruptor cannons created for the project. The disruptors in fact required a sustained output nearly as high as weapons found on for example the Eximius class and it's Class XII Pulse Phasers due to it's much faster cycle time.
This in turn had disasterous consequences when tested aboard a proto-type testing vessel, which exploded from generator overload. While the design team was still alive(a lesson learned from the early days of burst fire torpedo testing, which killed the entire development team) it was a rather major set back.
The High Council, initially balking at the suggestion of increasing the size of project 519-Ko simply decided to merge it with the older Project 615-Mek, which was a light cruiser design.
The end result was project 550-Ko which was a ship given a design displacement of 500,000 metrics tons, and a length of 318 meters. The High Council while balking at the concept of such a large vessel, tentively went ahead with the design.
Development with the help of the Staryards went relatively smoothly, and the Kron class was ready for full scale deployment by early 2380.
The Klingon Empire currently is laying down a total of 350 new keels per year, roughly 2 keels per every Vor'cha, and 1 additional keel to replace a K'vort class cruiser. These figures are expected to exceed 750 keels annually once the Klingon Empire begins full scale production of it's K'vek class, which will also have 2 Kron class destroyers as escrots. Total production figures are expected to total about 25,000 units.
K'vek
The K'vek class concept design was originally fielded in the mid 2350's as part of a study to create new ships to supplant and eventually replace the aging frontline ships in Klingon service. The Klingon Empire, while having better relations with the Federation, had simply felt that their ships were being quickly over-run by a plethora of new Starfleet designs, with intelligence reports on new ships such as the Nebula class and Galaxy class then in development.
While modernised varients of the K'vort, K'tinga and B'rel classes had served the Empire immensely well against the Federation's Constellation, Excelsior, and related classes which were serving the backbone of Starfleet, the Ambassador class had run a panic through the Klingon Empire which resulted in the horribly unbalanced and overweight QIn'Vagh class Bird of Prey battleship. The prospect of yet an even more advanced design with twice the volume of the Ambassador class set off warning bells through the Empire.
The original plan called for the creation of 3 seperate ship classes to respectively fill the role of a frigate, light cruiser, and attack cruisers. However internal strife within the Klingon Empire, particularly involving the House of Mogh, and House of Duras eventually killed the frigate and light cruiser designs, instead resources being concentrated on additional K'vort class cruisers, and the now named Vor'cha class attack cruisers. The K'vek class, which had been slated to take over the duties of the K'tinga class was shelved indefinitely.
With the resurgence of the modernization program under Martok, 2 light cruiser designs were proposed. A modernised K'vek, and the newer Project 615-Mek were the forerunners for this competition.
With the 615 being combined with the destroyer development project, the K'vek was quickly green-lighted with the first six keels laid down. This went smoother than expected due to the fact that the K'vek was easily built in shipyard facilities made to build, and later maintain the D7 series.
This is partly due to the fact that the K'vek is essentially a modern resurrection of the K'tinga, but also due to the economic constraints placed on the Empire. Given their current situation, the Klingons opted to try to share as many design characteristics to previous classes as possible. The K'vek tends to be a much more streamlined, jagged version of the K'tinga.
The K'vek class measures roughly 360 meters in length, almost 50% longer than the D7. Despite this, the core hull frame actually is almost compatible between the two. This has proven advantageous as the IKV Amor and IKV Vorgath were built using keels of decommissioned K'tingas in the process of being scrapped.
The K'vek class is being mass produced at twelve major facilities along the Klingon Empire, with a total of 100 keels laid down per year. 1 keel per every K'tinga class commissioned during it's hull design life, as well as 1 additional keel. This figure is expected to grow with time, and is expected to exceed 200 keels annually by 2390. Total production figures are expected to total roughly 11,000 units.