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

The Defiant

This article is one of what I hope will turn out to be an occasional series which cover the most important ships in Trek, or perhaps the ones I like. The intent is to go into more far more detail than I usually cover in the comments pages for any given ship.

Design and Build

In "The Search, Part 1", Sisko states that the Defiant was built for one purpose - to fight and defeat the Borg. This would mean that the very earliest that the project could have begun was 2365, after Stardate 42761.3 - the date of the episode "Q Who?", which introduced Starfleet to the Borg threat. Sisko said the project was shelved when the Borg threat "became less urgent". Presumably this refers to the defeat of the Borg cube by the Enterprise-D in "Best of Both Worlds, Part 2", which took place around Stardate 43999.1.

This would mean that the Defiant had an absolute maximum of 1,237.8 Stardate units for design and building. Using the common TNG formula of 1,000 Stardates = 1 year, this would equate to about 15 months.

The DS9 TM notes on page 121 that a number of the systems used were already available. It goes on to state that the Defiant was created by modifying a pre-existing "pathfinder" design which was entering systems-level testing. The design shown for this pathfinder is largely identical to what became the Nova class as seen in Voyager's "Equinox".

It's hard to know how seriously to take this. Modifying something like the Nova into something like the Defiant would take nothing more or less than a near-total redesign. It would be a far more extensive change than the Enterprise underwent from TOS to TMP, a change which had already strained the bounds of credibility.

It's also hard to know to what extent existing systems could have been used. If the TM is talking about power transfer conduits, artificial gravity generators, computer cores, replicators and such, then it seems perfectly reasonable enough that the designers would use off the shelf units to save time and effort. If they are talking about major components such as the warp core and coils, phaser cannon, and quantum torpedoes then it seems far less likely. The Defiant's warp coils, for instance, could not possibly have fitted inside the nacelles of a pathfinder/Nova type. It's also hard to understand why there was no mention of quantum torpedoes in Best of Both Worlds when the crew was talking about upgraded weapons systems, if these were an existing technology at the time.

The reasonable conclusion is that the Defiant may have inherited some of the less important systems from earlier designs, but that the overall design effort involved in the ship would be little short of that required to produce an entirely new class from scratch. The construction effort involved in producing the Defiant would presumably be much lower than that needed for even a small ship like the Intrepid - in volume terms the Defiant is around half the size of the Intrepid at most.

The most telling point concerning the Defiant's build time comes from "Shattered Mirror". In this episode we find that the Mirror O'Brien stole the plans for the Defiant during "Through The Looking Glass". The Stardates of both episodes are uncertain, but looking at the episodes around them and interpolating we get a date of about 48700 for "Through the Looking Glass" and about 49800 for "Shattered Mirror", so the episodes are only about one year apart. So even if the rebels conquered it the day after "Through the Looking Glass", they managed to build their Defiant in about one year, using only whatever construction equipment or materials they had to hand in a station whose primary function was as an ore processing plant.

Crew Complement

We have several references to the Defiant's crew, all giving figures in the region of fifty. The first comes in the episode "The Adversary". The ship has been sabotaged by a Founder, with devices planted in the control systems. Sisko states :

Sisko : "We've got forty seven people on board. Theoretically, any one of them could have planted these devices."

At the time this Founder is impersonating a Federation ambassador, so the actual crew complement would be 46.

Another figure is given in "Children of Time". In an alternate timeline episode Sisko meets Yedrin, a descendant of Jadzia Dax from a timeline in which the Defiant crashed on a planet in the Gamma Quadrant. Talking about the aftermath of the crash the two say :

Yedrin : "At first, everyone had to sleep here - all forty eight of them."
Sisko : "Forty eight?"
Yedrin : "Kira died a few weeks after the crash."

So the Defiant had 49 people on board when she crashed.

The next reference came in "Paradise Lost". A rogue Starfleet Admiral is ordering a subordinate to use Quantum torpedoes to destroy the Defiant, using the idea that shape shifters are on board to justify the attack. Sisko interrupts to say :

Sisko : "Captain, you know as well as I do that there aren't any shape shifters on the Defiant. Use those quantum torpedoes and you'll be killing fifty Starfleet officers."

So the Defiant crew would be 50 in this episode.

We might argue that the normal crew is 46-49 and Sisko rounded this to 50, but really there is no need. It's perfectly reasonable that all these figures could be correct - in real life you would expect the crew of a ship to fluctuate slightly as crew transfer in and out, or because people are left behind through illness or other factors.



The Defiant's main armament comprises four phaser pulse cannons. These are first seen firing in "The Search" and subsequently in many other episodes. The weapons face forwards and are located at the root of the nacelles.

inline image
This shot clearly shows the two port side pulse phaser cannon.

The pulse cannon initially appear to be fixed axis - that is, only capable of firing directly forwards. This would be a significant limitation for the weapons because it would make targeting extremely difficult. To hit a 100 metre object from as little as 500 kilometres would require an aiming accuracy of about a hundredth of a degree, whilst doing the same from 300,000 kilometres - a range we have seen beam weapons used at in Trek - would change this to about one fifty thousandth of a degree! Aiming a ship with this kind of accuracy would be an impressive feat indeed.

Fortunately, the episode "Paradise Lost" shows that the phaser cannon have a significant off-axis capability. In the episode the Defiant battles against another Starfleet ship, the USS Lakota. At one point the Defiant swoops over the Lakota and fires the main cannon, scoring hits on Lakota's dorsal surface :

inline image
Defiant fires on Lakota.

As you can see, the Defiant is scoring hits on the starship's shields roughly at the point where the front of the nacelles are. She is flying almost parallel to the Lakota - her nose may be down somewhat, but not nearly enough to be pointing at this spot. It's not so clear from this single still, but when watching the moving footage it is very clear that the Defiant's phaser pulses are emerging at a significant downward angle. The ability to fire even a few degrees off axis would give the Defiant much more flexibility in firing on an enemy during battle.

The Defiant also has at least two other phaser weapons, which can also be seen firing in "Paradise Lost" :

inline image
This shot shows a phaser beam firing from the nose section, underneath the deflector dish.

The episode "Starship Down" also shows this weapon being used :

inline image
Defiant destroys a Jem'Hadar ship with a phaser blast.

The episode "Rejoined" features the Defiant participating in an attempt to create an artificial wormhole. An energy beam is fired at a probe to create some sort of subspace matrix :

inline image
Defiant fires an energy beam.

This could represent some sort of separate energy beam emitter here, or perhaps the phaser bank was removed or modified for this experiment. But the the type of energy being used in "Rejoined" is never specified, so we can just as easily assume that it is a phaser beam. The beam shown above was of a wider spread and a different colour than normal phaser fire, but this is not necessarily a problem - firing wide angle beams is a known capability of phasers, and the colour could be a result of this and the use of a low power setting.

A moment after firing the shot from its nose section in "Paradise Lost", Defiant rolls and fires another beam from somewhere around the bridge collar. Phaser fire is also seen coming from this area frequently during the climactic battle in "Shattered Mirror" :

inline image
Another phaser firing from the dorsal surface.

inline image
Defiant fires on the Regency.

The beam looks as if it is emerging from directly on top of the bridge, though the images are fuzzy enough to justify putting it immediately behind the bridge instead. There is no sign of a phaser array in this area, so the best bet is probably to say that this is a single phaser emitter akin to the phaser banks carried by the Refit Constitution class Enterprise and other ships of that era. We should remember that this is an alternate version of the Defiant which could have a different weapons fit, but there is really no need to assume this. The episode does state that this Defiant was built from the original plans which the rebels had stolen, and since the same weapon has appeared in both the original and mirror version of the ship then it seems the rebels simply stuck to the plans.


The Defiant originally carried Photon torpedoes - in "The Search" Sisko orders O'Brien to make sure that the ship is carrying a full complement of photons. In the episode "Defiant" Thomas riker stole the Defiant and used it to attack Cardassian space. At one point he orders Quantum torpedoes fired and we see two torpedoes emerge from the triangular shaped areas on the forward hull :

inline image
Defiant firing quantum torpedoes.

These weapons are a different colour from the standard blue/orange/red photon torpedoes but otherwise appear identical in function. The non canon DS9 Technical Manual states that quantum torpedoes operate by using a matter/antimatter energy release to trigger a zero point energy charge, resulting in a yield much higher than normal torpedoes. After "Defiant", the ship would almost always use these weapons during battle, and you would be tempted to say that the ship was initially fitted with photon launchers which had then been replaced with quantum tubes. Unfortunately in the episode "The Adversary" a Founder seizes control of the Defiant and sends it on a course towards Tzenkethi space, arming the photon torpedoes. Since "The Adversary" comes well after "Defiant", we either have to speculate that the ship had the photon tubes replaced with quantum tubes, then went back to photons, then back to quantums again - which is clearly absurd to my mind - or we assume that the ship can carry and fire both photons and quantums at the same time.

It is certainly possible that the new quantum torpedoes could be designed to fire from all existing torpedo tubes - as it is photon tubes can already fire probes, so there is at least some flexibility in the size and shape of the objects they can handle. But if this were so then surely we would expect many other ships to start using quantum torpedoes during the Dominion war? Certainly the sovereign class Enterprise-E only ever fired quantum torpedoes from the rapid fire launcher on the ventral saucer surface and photons from all other tubes, implying that each launcher could handle only one kind of torpedo. Perhaps the tubes are backward compatible but not forwards - that is, perhaps quantum tubes can fire photon torpedoes but photon tubes cannot fire quantum torps?

As well as the two forward facing launchers Defiant has an aft launcher, which is seen firing in Paradise Lost :

inline image
Defiant fires an aft torpedo tube at the Lakota.

Notice that this is clearly a standard photon torpedo rather than a white quantum torp. This could be another explanation for why the ship carries both kinds of torpedo - it originally had three photon launchers and refitted the forward facing launchers for quantum torpedoes whilst leaving the aft launcher for photons. This would remove any need for cross-compatibility between launcher and torpedo types.

The Deep Space Nine Technical Manual shows a pair of aft torpedo launchers just aft and inboard of the nacelles, corresponding to the glowing red spots on the hull. This is an odd choice - these glowing areas look extremely like impulse engines and nothing like any torpedo tube we have ever seen. The DS9 TM puts three impulse engines at the very back of the ship, claiming that the lack of any external features on the ship in this area is because the exhaust is emitted through some sort of porous blank metal plate. Given that the Paradise Lost tube is fired from the aft centre of the ship, we must reasonably conclude that the DS9 TM is wrong. There is a single aft launcher in this location, and the glowing red areas are indeed the impulse engines. the other option is to conclude that Defiant actually has three aft torpedo tubes, two behind the red areas and one at the centre, above or below the centre impulse engine.

The Nose Launchr

The DS9 Tech Manual also puts a torpedo launcher in the nose section, beneath/between the navigational deflector emitters. There is an aperture here, which as mentioned earlier has been seen to fire phaser beams together with an energy beam which may or may not be a phaser. In the latter case, just seconds after Defiant fires the energy beam in "Rejoined" the ship launches a probe from the very same spot :

inline image
Defiant launches a probe.

If TNG is any guide then the ability to launch probes should also indicate the ability to launch photon torpedoes from the same area, though this is not certain.

As if it isn't bad enough having a phaser and probe launcher in this aperture, the episode "One Little Ship" shows a tractor beam being emitted from this same opening!

At the very least, this leaves us with a phaser bank, a tractor beam emitter and a probe launcher. Even assuming a length of 170 metres as stated in the DS9 TM, this area of the ship is no more than about 2 or 3 metres across at the very most. It is hard to believe that such a small area could contain all three items.

One possibility is that there is only a launcher here, but that it handles some fairly specialised probe types. You should be able to fit a probe with a phaser or tractor beam emitter, and it is conceivable that the probe could be loaded and then the beam fired from within the tube. Such technology could even explain the famous FX error in TNG's "Darmok" in which a phaser beam was fired from the forward torpedo launcher. It does seem like a fairly impractical proposition though.

My own conclusion is that there is a probe/photon launcher in this location, with a phaser beam and tractor beam emitter crammed in beside it. This is somewhat unsatisfactory, but less so than other explanations.

In conclusion, then, Defiant's weapons can be summarised as follows :

NumberWeaponLocationSeen In
4Pulse Phaser CannonAt root of nacelles"The Search", various other episodes.
1Phaser emitterOn/behind bridge"Paradise Lost", "Shattered Mirror"
1Phaser emitterIn nose section"Paradise Lost", "Starship Down"
2Quantum tubesForward hull"Defiant", various other episodes
1Photon tubeAft hull"Paradise Lost"
1Probe/photon launcherIn nose section"Rejoined"


Defiant is fitted with a shield system which has always appeared as a normal bubble shield - I don't recall any case where conformal shields have been used. The Defiant's shields have apparently held up against the Dominion's phased polaron weapons right from the beginning, which makes it hard to understand why Weyoun found it hard to believe that the Federation shields on Deep Space Nine held up against the same weapons in "A Call To Arms". Perhaps one could argue that those Jem'Hadar who actually fired on the Defiant never lived to tell the folks back home that the ship could take it!

As well as the shields, in "Paradise Lost" we find that the ship is fitted with ablative armour. The word "ablative" indicates armour that vapourises off when fired upon, so carrying the energy away from the target. In reality this would mean weapon hits would leave very visible markings on the surface of the ship, something we rarely see happening. The dialogue in Paradise Lost makes it clear that the armour was added without Starfleet's knowledge, or at least without Admiral Leyton's knowledge. It may be that Defiant is considered super-secret and information is on a strictly need to know basis, or it might be that O'Brien fitted the armour without telling anybody. If the latter, it would be an impressive achievement for the Chief.


Only the infamous Klingon Bird of Prey has been shown at a more bewildering spread of sizes than the Defiant. I'm not going to try and deal with this issue in anything like the kind of depth that I did for the BoP, but I will do a quick review of some of the different sizes we have seen the ship at over the years.

Official Scources

On page 121 the DS9 TM states : "the final dimensions of the new ship became 170.68 by 134.11 by 30.1 metres".

This figure is fairly widely accepted because the DS9 TM was co-written by Rick Sternbach, Herman Zimmerman and Doug Drexler, all crew insiders on DS9 who would be expected to know their stuff. The rather less authoritative Star Trek Fact Files (28/1) gives the ship a length of 68.58 metres, which would not be too far off the size depicted in First Contact. The Encyclopedia size charts (3rd edition, page 687) show the Defiant at around 200 metres as compared to a 289 metre Constitution class.

Star Trek: First Contact

In this movie the Defiant takes on a Borg cube, and is badly damaged. The Enterprise-E swoops in to the rescue. As we can see in the image below, the E-E dwarfs the tough little ship; indeed given that the Defiant is somewhat closer to us than the Enterprise-E in this image, it would actually be even smaller than it appears at first glance!

inline image
The Enterprise-E swoops past the Defiant.

Given that Picard later describes the Enterprise as "almost seven hundred metres long", the Defiant would be no more than about 40 metres across in this image. That would make it about 45 metres long, barely much larger than the Delta Flyer! At such a size the Defiant could not possibly have more than one or two decks, yet we have repeatedly heard references to decks 3, 4, and even on occasion 5.

Deep Space Nine

Next to a Bird of Prey, Defiant usually appears to be about the same size :

inline image
Defiant next to Martok's Bird of Prey.

But this hardly helps us much because the Bird of Prey has no consistent size either, having been depicted at everything from 35 to 650+ metres!

"By Inferno's Light" gives us a good comparison between the Defiant and a Danube class Runabout:

inline image
Defiant takes a runabout in tow.

The DS9 TM states that the Danube class Runabout is 23.1 metres long, a figure which has not been greatly disputed. As you can see from the above image, this would mean that the circular feature on the Defiant's underside would be around 30 metres in diameter, which would make the entire ship some 170 metres long - good agreement with the TM's figure for the length of the Defiant.

The episode "The Sound of Her Voice" gave us even more confusion. The circular feature which above generates a tractor beam now became a shuttlecraft hangar door, from which emerged a Type 10 shuttle :

inline image
A Type 10 drops clear of Defiant.

Again according to the DS9 TM, the Type 10 shuttle is 9.64 metres in length. That makes this opening a good 15 or so metres across, which would make the overall length 85 metres or so. This is way off the 170 metres in the TM, which would require the shuttle to be at least Runabout-sized. of course since the DS9 TM is not canon, we could simply say that the Type 10 is Runabout-sized.

It is also questionable as to whether the shuttlebay can be reconciled with the tractor beam emitter above. Clearly the area looks nothing alike in the two images - the entire structure visible in "By Inferno's Light" has vanished. Since "The Sound of Her Voice" takes place almost two full years after "By Inferno's Light", the only reasonable assumption is that the ship underwent a major modification in the interval which installed a new hangar bay.

In "Shattered Mirror" we get a look at some engineering schematics for the Defiant. It looks more or less identical to the DS9 TM diagrams section and the MSD MSD display seen on the bridge. The TM picture helpfully shows people standing around in the ship, which enables us to scale it. Assuming a height of 1.8 metres is normal for a Human then as now, the Defiant's length comes to about 115 metres.

inline image
The Defiant's MSD

The MSD has very frequently appeared in episodes, albeit usually as a rather indistinct image in the background, so we could say that this length has a great deal of canonical support. But the canonicity of things like this is somewhat open to question - after all, we don't generally consider the various gags and in-jokes which appear on these displays (such as the Porsche and the giant duck which appear on the E-D's MSD) to be canon.

To summarise, then, sizes of much less than 100 metres are occasionally depicted, but this is really too small to be credible. Sizes in the 85 metre range are somewhat more sensible in this respect, and have canon support from "The Sound of Her Voice", but are really still not big enough.

Sizes in the 115 metre range would fit in well with 4 decks. It also works well with Martok's Bird of Prey, if that ship is indeed 109 metres long. Perhaps most importantly, it works well with the canon MSD. On the other hand this length is contradicted by "By Inferno's Light", and such a blatant scene might be considered to over-ride something like a computer display even if it is a frequently seen one. It's also out of line with the DS9 TM and "The Sound of Her Voice".

The 170 metre size has the benefit of being the "official" length in the DS9 TM, and works well with "By Inferno's Light", but it doesn't work with "The Sound of Her Voice" - unless we over-ride the DS9 TM length for the Type 10, and it seems hypocritical to use the manual to support one size and then disregard it again a moment later.

In the end I would say that there's really no way to know for sure what the "true" length is, but that the sensible choices are 115 metres or 170 metres. For the purposes of this site I decided to use 170 metres simply because I had already used much of the information in the DS9 TM.

Tractor Beams

We have seen that there is a tractor beam emitter on the ventral surface in this image from "By Inferno's Light" :

inline image
Defiant takes a runabout in tow.

This emitter and the structure which it stands on was apparently removed by the time of "The Sound of Her Voice", to be replaced by a hangar bay. We see another emitter on the dorsal surface in "For The Uniform" :

inline image
Defiant tractors a Cardassian freighter.

This emitter is in the centre of the hull, right near the stern of the ship - actually right about where the aft photon torpedo launcher is. This emitter is also used to tow a Jem'Hadar ship in "The Ship"; indeed, the tractor beam was apparently used to drag the crashed vessel out of a rock face and haul it up into orbit! This would be a pretty amazing sight which we unfortunately didn't get to see in the episode. We see another tractor emitter on the ventral surface in "The Way of the Warrior" :

inline image
Defiant uses a tractor beam on a Vor'Cha class attack cruiser.

This emitter is just about where the dorsal phaser bank is located. We also see a tractor beam being emitted from the nose section in "One Little Ship"; apparently both the nose and dorsal emitters are right next to a phaser bank.

So the Defiant was apparently built with four emitters, but this was later cut back to three.


I've never really liked the Defiant - even at 170 metres she's simply too small for the role she's supposed to fulfil. look at the phaser cannon - each one is a tiny fraction of the size of the Type 10 phaser arrays carried on a Galaxy class starship, yet Defiant is supposed to be a heavily armed ship. I'd far rather have seen something in the same size class as Voyager, with phaser cannon that were five or ten times the size relative to the length of the ship - I'm thinking of weapons like that huge cannon thing the Enterprise-D had in "All Good Things". I'd probably have made those disruptor cannon instead of phasers as well. I'd also have laid the warp core down horizontally and had two instead of one.

In a detailed examination of the ship it becomes clear just how unsure the writers have been of its capabilities. To some extent that is true of many Trek ships. The Enterprise-D is probably the most carefully thought out ship design in Trek history, with the possible exception of Voyager, but even the Galaxy class went through a few minor issues in its time concerning where phasers fired from or what holodecks did. But I can't think of a major ship design that has suddenly had an entire shuttlebay appear out of nothing, or which has used a single hull feature for at least three different things. Clearly the writers and the special effects people made up the Defiant's capabilities more or less as they went along, and this resulted in a good deal of confusion. I'd be prepared to bet that even by the high-pressure standards of television production there wasn't a great deal of time to think through the Defiant before she appeared on screen.

Additionally, at least part of the problem is probably related to the ship's role. Starships are by their nature large multi-role platforms - even the smaller ships such as the Constitution and Intrepid classes are at least as large as the largest of present day warships, much larger when you consider volume rather than length. there is plenty of room to include all kinds of extras and goodies, which the ship designers are only to happy to do. Defiant, on the other hand, was meant to be a 'stripped down' design which was only really capable of fighting. It's entirely possible that the designer deliberately chose not to include every bell and whistle on the ship with this in mind. When the writers then did decide to have the ship going on science missions and launching shuttles, the special effects people might have found themselves having to improvise as best they could.

Though I don't like the thinking behind the ship, I do have to admit that has a lot of screen presence. It has a businesslike, menacing look which suits its role perfectly, and it certainly did give Deep Space Nine a much needed shot in the arm. That alone makes this tough little ship a major success.

Colour key

Canon source Backstage source Novel source DITL speculation

© Graham & Ian Kennedy Page views : 79,652 Last updated : 16 Jan 2021