Cookie Usage Statistics Colour Key Sudden Death Monthly Poll Caption Comp eMail Author Shops
Ships Fleets Weaponry Species People Timelines Calculators Photo Galleries
Stations Design Lineage Size Charts Battles Science / Tech Temporal Styling Maps / Politics
Articles Reviews Lists Recreation Search Site Guide What's New Forum
Constitution Class Klingon Battlecruiser Klingon Bird of Prey Magazine Capacity NX Class Phase Cannon Sovereign Changes Star Trek : Discovery The Defiant The USS Franklin Borg History Money Monoculture Religion in Trek Technology Levels The Ba'Ku Land Grab Trills / Dax Abrams Speed! Antimatter Phasers Romulan Warp Drive The Holodeck Torpedo Yields Transwarp Theories Tri-cobalt device Warp in a Solar System Warp Speed Anomalies D'Deridex Class Weapons Galaxy Class Shields Galaxy Class Total Output Galaxy Class Weapon Output Genesis Weapon Power Husnock Weapons Intrepid Class Total Output TOS Type 2 Phaser Power Trilithium Torpedo Power Dangling Threads Enterprise Ramblings Eugenics War Dates Franz Joseph's Star Trek Here be Remans? Live fast... Write Badly Maps Materials Nemesis Script Random Musings Scaling Issues Size of the Federation Stardates The Ceti Alpha Conundrum The Size of Starfleet Trek XI Issues

Klingon Battlecruiser


This is one of those things that "Enterprise" has forced a big rethink on, so far as this site is concerned. Even by Star Trek standards the makers of the show have now got an incredible amount of mileage out of this model, having used one version or another of it over some 35 years of real time, or 226 years of the show's timeline!

It strains credibility, to put it mildly, that a single class of vessel could remain in service for over two and a quarter centuries, even with refits - imagine trying to retrofit a wooden sailing ship of the 1770s with surface to air missiles and turbine driven propellor engines! But we're now stuck with it.

In all fairness, the appearance of the ship on the Enterprise episode "Unexpected", which added over a century to its known service life, appears to be a result of time and budget constraints rather than apathy towards continuity on the part of Berman and/or Braga. A new Klingon battlecruiser model was apparently being made for the show, and will appear in future Enterprise episodes. Presumably this could not be ready in time for use on "Unexpected". As usual, this article will examine the evidence and try to propose a reasonably common sense explanation for it all.

The Original Series

The TOS battlecruiser design was first seen in the episode "Elaan of Troyius". The ship was even less like the standard "flying saucer" ships of the period than the Enterprise itself. It also made excellent sense as a warship, with the big engineering hull and compact forward section contrasting well with the Enterprise's big saucer section to accommodate all the science labs and comfortable crew quarters. This image shows the model used during TOS :

inline image

Note the clean surfaces and the colour scheme, which is very similar to the one used on the Enterprise. The same vessel was seen in "The Enterprise Incident" (as a Romulan ship bought from the Klingons) and "Day of the Dove". Although the ship was never called anything except a "Klingon ship" or a "Klingon battlecruiser", it has become widely known amongst fans as a "D7 class" ship. Several other episodes mentioned Klingon vessels without showing them, especially "The Trouble With Tribbles", "Errand of Mercy" and "Friday's Child".

Deep Space Nine

Although a Klingon battlecruiser was mentioned but never seen during the Original series episode "The Trouble With Tribbles", we get a second chance at this ship in the Deep Space Nine sequel to that episode, "Trials and Tribble-ations". In this episode the DS9 crew travel back in time and play a part in Kirk's mission, albeit a covert one. The makers created new models of the Enterprise, Space Station K7 and the Klingon battlecruiser for this episode. When the Klingon ship approaches, Major Kira specifically identifies it as a D7 class battlecruiser. This is what we see on screen :

inline image

Note that while the colour scheme is somewhat greener than the TOS model this ship has the same clean hull, with the exception of a feather pattern scored into the dorsal engineering hull. The fact that this pattern is actually built into the hull, rather than being painted on, could be taken to indicate that this ship is of a different class than the TOS model, except for one thing - during TOS we never saw a shot of the top of any Klingon ship! So all we need to do in order to make this and the TOS ship identical is to assume that all TOS ships had this hull detailing, and that some captains painted their ships white while others preferred green.


Alas, Voyager then mucked things up with the episode "Prophecy". In this episode Voyager encounters a Klingon ship which has been wandering the galaxy since setting off from their home space "over a century" ago. The ship is described specifically as a D7 class, a class which was retired "decades ago". This is the ship we see :

inline image

Note the glowing nacelles, clearly different from either the TOS or the "Trials and Tribble-ations" version of the ship. Yet this vessel is canonically of the same class, as stated in dialogue. We could try to explain the variation in nacelle design away by saying that nacelles only glow when the ship is at warp, but this does not match the facts - the nacelles are clearly glowing on the ship in the above image, yet it is cruising at impulse in this shot. Indeed, the "Prophecy" ship was at impulse throughout its battle with Voyager and subsequent destruction. None of the TOS versions of the battlecruiser ever showed any glow to the nacelles, either when they were orbiting a planet as in "Day of the Dove", or at warp as in "Elaan of Troyius". This can only mean that there are two variants of the D7, the one seen in TOS/DS9 and the one seen in Voyager.


As mentioned in the introduction section, in the Enterprise episode "Unexpected" we see an early Klingon battlecruiser :

inline image

This is clearly the same ship seen in Voyager - both hull and nacelle design are identical in every detail, since the same model was used in both episodes. So we are stuck with the fact that this variant of the D7 class, already established as being in service until "decades" prior to 2377, was also in service at least as early as 2151. Indeed if we assume that this vessel was a common Klingon design of the time, rather than being the first of their latest and best class, then it would probably need to be in service for at least five years or so prior to 2151. Interpreting the "decades"since these ships had been retired to ninety years - as far as it is reasonable to go - we are left with this being the original D7 class, entering service sometime prior to 2151 and remaining in service until 2287, a service life of 141 years. This doesn't really make a great deal of sense - just look at how ship designs have changed since the 1860s, or compare the Wright brother's aeroplane with the F-22 of a century later. The technology of Starship design seems to evolve much more slowly than ships or aircraft, but Picard's Enterprise is still a much different beast than Kirk's even though barely one hundred years separates them. If anything Klingon designs should evolve even faster than their Federation equivalents - technology always advances fastest during time of war, and the Klingons of the pre TNG era appear to live in a state of almost perpetual warfare.

However, we are stuck with the fact that this design was indeed in service for this length of time. The best we can do is to assume a program of rolling updates which would replace virtually every major internal system over the years. Additionally, we could suppose that this version of the D7 was considered to be a first class combatant in 2151, but was very much relegated to a supporting role in 2287, much as many Huey helicopters are still in service with the US military even though the Blackhawk is taking over the lead role. Certainly it is not hard to believe that a group of Klingons who wanted to leave the Empire forever to wander the galaxy had to settle for a less than state of the art vessel to do it in.

The Motion Picture

The first Star Trek movie presented us with a new version of the battlecruiser :

inline image

This ship is significantly different from either of the two versions of the D7 that we have looked at so far, although it is similar to both. It lacks both the glowing nacelles of the Enterprise version of the ship and the clean hull surface of the TOS version. The class name or number is never stated on screen, but novels and other backstage sources have dubbed it the "K'T'Inga" class. In the TNG episode "Heart of Glory" some stock footage of one of these ships was re-used, so we know that this version of the battlecruiser entered service in 2271 and was still in service as of 2364. This service life of at least 93 years is not so farfetched as the 141 years of the initial D7 variant, but still pushes credulity compared to a real world service life of 30 - 40 years. Again, we can assume a program of refits and upgrades followed by a descent from front line combat unit to supporting roles. The fact that the ship in "Heart of Glory" was being used to recapture escaped prisoners could be taken to imply that the K'T'Ingas were no longer considered to be front line combat units by the 2360s.

Star Trek : The Undiscovered Country

Another version of the battlecruiser was seen in the sixth Star Trek movie. "Kronos One" (my Klingon isn't up to the original spelling) carried Chancellor Gorkon to a peace meeting on Earth, apparently serving as a Klingon version of "Air Force One", the American President's personal 747 airliner. The ship had the same hull detailing as the TMP ship, although the colour was somewhat lighter, but different nacelles :

inline image

Although this ship has glowing nacelles similar to those of the early D7 seen in Enterprise, a close up view reveals that the detailing on the nacelles is somewhat different. This ship is therefore not another variation of the D7, but rather a variation of the K'T'Inga. Since ST VI is set in 2293 we know that these ships must have been in service from at least this date. It is a matter of speculation whether the Klingon chancellor would choose a state of the art vessel just entering service as his personal transport, or opt for an old well proven design instead. I choose to believe the former, since it allows us to keep the service life of the ship to a reasonable minimum.

Deep Space Nine

In "The Way of the Warrior", DS9 came under attack from a Klingon fleet which included many battlecruisers. We get one good close up of these ships :

inline image

Although the colour of the glowing section of the nacelles is greener than on Gorkon's ship, the detailing of the nacelle and hull is identical to the Klingon vessel. More of these ships were seen in later episodes, so apparently this variant of the K'T'Inga class remained in service from Star Trek VI - 2293 - up until at least 2375. Interestingly, some of the ships in "Way of the Warrior" are seen firing beam weapons - presumably disruptors - from their forward torpedo tubes, indicating that the torpedo system had been pulled out at some point in the last eighty or so years.

Unfortunately, Deep Space Nine also brings up a contradiction with Voyager. We have already seen that the original D7 seen in "Enterprise" was again seen in Voyager, where it was described as having been retired "decades" ago. Yet in the first part of the DS9 final episode, "What You Leave Behind", shortly before the Allied fleet arrives at Cardassia we see this shot :

inline image

The ship above and behind the Defiant is clearly an original version D7, identical to the class Voyager met in Prophecy, still in service. It's hard to tell what kind of ship the battlecruiser at the bottom right is, but it looks like the same type. There are several possible ways to explain the appearance of this ship decades after it was retired; it's possible that Tom Paris could have been mistaken about the D7's retirement, though this seems unlikely. It's possible that yet another variant of the battlecruiser, identical to the original D7, entered service after that ship retired. But the most likely explanation is that the Klingons put these ships into mothballs when they were retired, and that they were subsequently reactivated for the Dominion war.


It is certain that the earliest known version of the D7 entered service in or before 2151 and remained in service until at least 2276. This version was also in service in 2375, so it is possible that Paris was mistaken about their retirement, giving them an active service life of over 224 years. More likely is that they were retired sometime around 2276 and then brought back into service for the Dominion war.

It is certain that the vessel seen in "Trials and Tribble-ations" was also a D7. We can only speculate as to when this variant entered service - for all we know it could pre-date the Enterprise version of the ship by centuries! My preference is to keep the service life of any ship to below a century, so I presume the Enterprise version to be the first D7 class battlecruiser, with the TOS version as a variant of it.

It is also quite possible that the K'T'Inga class is a further variant of the D7, although non-canon sources indicate that this is not the case. My own preference is to accommodate the novels by calling this a new class, albeit obviously sharing a good deal of the design.

This gives us two distinct classes of Klingon battlecruiser, each with two variants :

35 metres0.321K'pakSeen in 'Way of the Warrior'. Name is speculation.
109 metres1Bird of Prey
Actual designed size of the original model, supported by most of the evidence from ST III/IV. Variants of similar size appear in further films and TNG/DS9. D numbers of all but the D12 are speculation.
327 metres3B'relSeen and named as the B'rel in 'Rascals'. Ships of this approximate size in TNG are assumed to be B'rel class also.
654 metres6T'paiSeen in 'The Defector'. Name is speculation.

Over their long lives, one would expect these ships to be refitted and updated to such an extent that they would be new in all but name - the proverbial axe which has had ten new handles and six new heads springs to mind. Yet the Klingons have apparently never deemed any changes sufficient to warrant a new class designation.

Although the Klingon Battlecruiser is an extreme example, in many respects it is symptomatic of a wider problem with Star Trek technology; the rate of technological advance within the Star Trek galaxy appears to be amazingly slow!

Let's have a little history lesson...

inline image
Separated in time... but only by 74 years.

The Wright Flyer from 1908 could never pass for an F-117 from 1982. There are so many differences between these two aircraft that they could hardly be listed. They are also worlds apart in terms of performance; the F-117 is dozens of times faster than the Flyer, or even its more practical successors. And the F-117 is not a great performer by modern standards, there are many aircraft that are several times faster, larger, longer ranged, etc. Imagine a comparison with Concorde, or even the space shuttle...

inline image
Better... HMS Victory, and the USS Barry.

The Victory is the world's oldest commissioned warship, dating from the late 1700s. The Arleigh Burke class destroyer USS Barry was launched in 1987, over two hundred years later. There are some similarities; the hull shape of both ships is vaguely similar because both are designed to travel in the same medium and both have somewhat similar masts, though those masts serve a very different purpose on each ship. Both also fire what could be termed "projectile weapons". The Barry's 5" Cannon and CIWS work on the same basic principle as the Victory's cannon did and even surface to air missiles are projectile weapons, though of a more advanced sort.

inline image
That's more like it!

The American submarine Turtle, from 1775, compared to the USS Seawolf from 1997. Even though this still doesn't quite match the 224 year plus span of the D7, the differences between the two designs could hardly be more obvious. Both ships have propellors and a rudder, but that's about it.

inline image
Spot the difference...

Obviously, the D7 hasn't changed much over the years. However, when you look at the real world examples listed above it becomes apparent that Federation designs haven't actually evolved all that much either!

In Star Trek, we have seen the same basic design of ship in service from TOS through to the end of Voyager. If you compare Kirk's Enterprise to Picard's Enterprise-E, they are both extremely similar designs. Both have an engineering hull, with a saucer attached at the same place, both have the warp drive in nacelles which are at the end of struts. Those struts attach to the engineering hull and nacelle in much the same place; in both they slope upwards. The nacelles both have glowing bussard collectors at the front. The Saucer section has a bridge, which is in the same place on both ships. The Navigational deflector is in the same place on both ships.

Perhaps more troubling, the technology underneath the hulls are almost exactly the same. Both the E and the E-E use matter/antimatter power generation. Both are armed with phaser weapons. Both are armed with photon torpedoes. Both have shields for defence. Both use the transporter for getting from place to place, with both transporters apparently having all but identical performance characteristics.

I could go on, but I trust the point is made. To some extent we can argue this problem away. The Victory's hull is similar to the Barry's because they both travel in the same medium. The E and the E-E both travel via subspace, and so you could expect that their hulls would be somewhat similar. But this brings up the question of why both ships use the same drive system - after all, we have gone from sail to paddle wheels to propellers in the space of a couple of hundred years or so. But on the other hand, prior to the switch to paddles and propellers sail ruled the seas for some thousands of years. Compared to that, a few centuries of warp drive is nothing.

The similarity in weapons could also be explained away. Yes, both ships use phasers - but a phaser array as seen on the E-E is potentially as different from the (apparently) simple cannon of Kirk's Enterprise as the Barry's 5-inch gun is from the Victory's muzzle loaders. Torpedoes are slightly better - although the E-E does carry photons, it also carries the more advanced quantum torpedo. It's not clear just what kind of advance the quantum torpedo represents, though - they seem to pack roughly the same punch as photons and to travel roughly as fast and as far. In fact the only "advance" they do seem to offer is that they are a different colour! But we can always assume that they are better at penetrating shields or some-such.

So there is nothing inherently impossible about the relatively small change in technology between Kirk and Picard. Nevertheless, should any future incarnation of Trek ever be set in the post-Voyager era, it would be nice to see some real revolutionary changes in design and capability. Introducing some advanced drive technology could offer the opportunity of significantly changing the overall hull layout. We've seen that standard Starfleet ships can travel in both transwarp and slipstream without significant modification, at least for the short term, but a ship built to include one of these from the outset could offer a significantly different hull design. Weapons could get away from the whole "fire a beam/ball of light at the enemy", perhaps by equipping a future ship with remote controlled drone weapon platforms.

Probably this won't happen. The design of ships in Trek is prompted far more by what looks "cool" than what makes sense from a technical point of view, and the fictional Enterprise has become such an icon that it's unlikely any Trek show will stray too far from it. Besides, if Enterprise is a success - which it probably will be - then the producers might never return to the post-Voyager timeline. It's a sad thought, but maybe the Enterprise-F and her successors will only live in the mind of obsessive techno-fans like me...

Colour key

Canon source Backstage source Novel source DITL speculation

© Graham & Ian Kennedy Page views : 111,430 Last updated : 16 Jan 2021