Klingon D-6/"Chal'Jach" intelligence report (Earliest known type shown).
All specifications are estimates unless otherwise indicated.
Star Fleet Intelligence (SFI) has given this report a 95% reliability rating.

General Specifications:

Length: 49m (Confirmed)
Width: 52.25m (Confirmed)
Height: 18.75m (Confirmed)
Max Warp: 7.25 - 9.05
Cruise: 6.5 - 8.2
Max. Impulse: 0.52 - 0.84 lightspeed
Crew: 6-15 personnel (est.)

Armaments: Two lasers, later disruptors (fwd); one missile launcher (fwd -- later upgraded to a torpedo launcher).

Type: Fast frigate

About Ship: The D-6/Chal'Jach (Thunderstorm -- literally: "Sky [that is] Angry") was a fast, frigate-sized vessel used by the Klingons starting in 2247. The Chal'Jach was originally constructed for use as a merchant escort. Tensions with the Federation increased during the mid-23d century, and the Empire was concerned about the large numbers of new ships the Federation was constructing. Many of these new Federaton vessels were quite effective combat ships, and the Imperial council did not for a moment believe that calling a sword a plowshare made it so. In 2243, the council issued a decree ordering an uprated frigate be designed and built. As time was imperative, the council ordered an uprated version of the "Fox" frigate (the new version is called "Wolf" by Starfleet Intelligence) but also decreed that a new type of frigate be designed and built.

The Chal'Jach was a "clean-sheet" design, allowing Klingon engineers to sculpt a completely new shape that reflected a better understanding of warp field dynamics. The new shape allowed the Chal'Jach to reach hitherto undreamed-of velocity at lower power consumption than ever before. Armaments were initially two lasers mounted on turrets under the bridge structure. These were eventually upgraded to disruptors. The Mk I Chal'Jach was armed with missiles, but the type was eventually upgraded to torpedo armaments.

The Chal'Jach was a very agile ship with respectable range and considerable firepower for a vessel of its size. It's performance was so impressive that the Imperial council ordered a battle cruiser be built using the same basic pattern (the D-7, later known as the K'Tinga, following an extensive refit). The Chal'Jach is, due to numerous upgrades in equipment, still in service at this time.

Starfleet gratefully acknowledges the cooperation and assistance of its counterparts in the Klingon Imperial Defense forces for providing much of the historical data regarding this vessel.