Imperial Star Destroyers vs Mass Effect Reapers

Reapers can tank the main guns of 4 Alliance Dreadnoughts before they even begin to lose their shields. An Alliance Dreadnought's main gun can fire a round with as much energy as 38 kilotons of TNT every two seconds, or about 160 TeraJoules, so you'd need a constant stream of energy well in excess of four times that to take down a Reaper. The Hiroshima bomb was roughly 15 kilotons of TNT, or 63 TeraJoules of energy.

Imperial Star Destroyers are nearly 3 times the size of an Alliance Dreadnought, and is equipped with hundreds of Turbolasers and Heavy Turbolaser batteries. The power of a single twin Turbolaser, to say nothing of the 8-barrel Heavy Turbolasers that are the Star Destroyer's primary weapons, is enough to melt an ice moon measuring 1000km in diameter. 

Let's see how much energy it would take to melt that. Let's be really conservative for simplicity. Assuming the ice is already at 0C, you would need 333 kilojoules per kilogram of ice to turn it from a solid to a liquid. We know how big the ice is, so let's convert that to kilograms. Ice has a density of 917 Kilograms per cubic meter, so we need to convert what we know into cubic meters.

An object of 1000km in diameter has a volume of roughly 524,000,000 cubic km. A cubic kilometer is 1 billion cubic meters, so 524,000,000,000,000,000 cubic meters of ice. The mass of that object is ~480,508,000,000,000,000,000 kilograms, and we would need 333,000 joules per kilogram to melt it.

This means the power of a single Turbolaser is enough to output 160,009,164,000,000 TeraJoules of energy, or 2.5 quadrillion Hiroshima bombs. In conclusion, HOLY SHIT, that is one dead Reaper!

If that seems like bullshit, it kind of is. To put that in perspective, the Sun outputs 400,000,000,000,000 TeraJoules of energy every second, which is enough to power a Turbolaser, but since the Star Destroyer has a couple hundred of those Turbolasers, the Star Destroyer would need to generate dozens of times more power than the sun to power those weapons. This is what happens when you pick a fight with a cool spaceship from space fantasy, and you're from a universe that does its best to ground itself in what might actually be possible. It cheats, and you just plain lose.

And yet the entirety of Death Squadron couldn't pump out enough power to overcome that one second-hand shield generator the rebel alliance managed to build on Hoth. Death Squadron had a SSD with 2000 turbolasers and 2000 heavy turbolasers...and at least five Imperial class destroyers as well.

I do wonder why the rebels didn't put those things on every ship that could fit them, tbh.

Here is a nice analysis:

http://stardestroyer.net/tlc/Power/index.html

And that single twin turbolaser you're talking about is a Munificent-class turbolaser which one of the largest with 82 meters in lenght.

http://starwars.wikia.com/wiki/Munificent-class_star_frigate

But I would say that the melting an ice moon part is a bit overblown.

Isn't almost all of this information taken from the expanded universe which Disney declared non-cannon?

But even if it isn't, this makes no sense. If this were actually true then there would not even be a point in building a death star.

Yes, it's almost like the people who write Star Wars fiction are just making it up as they go along.

Perhaps we can test this with a GC3 mod in the future.  

Apparently each Imperial class star destroyer is the equivalent of a Geth Dreadnaught in scale.  We'll pretend the whole melting the ice moon thing didn't happen.  Soldiers tell tall stories all the time.  

Quoting marigoldran, reply 6

Perhaps we can test this with a GC3 mod in the future.  

Apparently each Imperial class star destroyer is the equivalent of a Geth Dreadnaught in scale.  We'll pretend the whole melting the ice moon thing didn't happen.  Soldiers tell tall stories all the time.  

I agree. "Scifi writers have no sense of scale" on full display right there.

There are times where Star Destroyers vaporize rock in ESB, but that's another story.

EDIT: http://www.stardestroyer.net/tlc/Power/

So, based on this, a single turbolaser bolt would have roughly half the power of a hiroshima bomb (~30 TJ). We need 640 TJ to break the Reaper's Kinetic Barriers. Multiply 30TJ by how many turbolaser batteries a Star Destroyer has, and the Star Destroyer still comes out ahead, but on a much smaller scale. The Star Destroyer would need to lay down constant fire from 22 of its batteries to break through the kinetic barriers, with the rest of the blasts doing damage to the Reaper's hull.

http://starwars.wikia.com/wiki/Imperial_II-class_Star_Destroyer

8 octuple barbette Turbolasers (8x8 = 64)

50 Heavy Turbolasers

50 Turbolasers

26+ Additional Turbolasers 

20 Heavy Ion Cannons

Of course, we'd still have to figure out how strong the Star Destroyer's own shields are, because the Reaper might kill the Star Destroyer before it gets a chance to fire all its main batteries.

One thing to note about the star wars universe is that while the galactic community in Mass affect has only existed for a few centuries, the star wars universe has existed for literally hundreds of thousands of years. There is barely even any mention of pre-space civilizations in the expanded universe, and the few that are mentioned are considered utterly ancient.

This is actually another problem I have with the expanded universe and also an example of "Scifi writers have no sense of scale". How would it even be possible to guess how a space society that old would even look like? Most likely everybody would have just evolved into space gods like the Vorlons from Babylon 5 or something.

The Reapers  have been around for millions of years.  

Note that the page linked lists 30 TJ as the energy required to melt the asteroid; 250 TJ is the figure given as the estimate for vaporizing the asteroid and the page suggests that vaporization is likely to have occured. Also note that this figure is not for the Star Destroyer's heavy guns, it is for a 'medium-size bolt' presumably from a medium turbolaser cannon. Furthermore, this is for a single bolt. A battery consists of two or more guns unless we're using very nonstandard terminology and so a single battery's fire would consist of two or more bolts per firing cycle.

I would further note that it is not at all clear that the kinetic barriers of the Mass Effect universe would provide any protection at all against turbolaser fire. Lasers are explicitly not blocked by the kinetic barriers of capital ships in Mass Effect, though Reaper shields apparently are partially effective against them (here, last paragraph of the combat section), and I could not say whether or not turbolasers are sufficiently close to lasers in the manner in which they would interact with Mass Effect's kinetic barriers to render Mass Effect's kinetic barriers similarly useless.

I would also question where your figure of 'constant fire from 22 of its batteries' comes from. If the barriers require only 640 TJ to break and each gun fires a bolt which can deliver a minimum of 30 TJ, then that is one bolt from 22 guns (no more than 11 batteries, unless we're using nonstandard terminology; again, in standard nomenclature, a battery consists of two or more guns), not 22 batteries. Furthermore, the kinetic barrier would need to be restored fully between every firing cycle in order to require 'continuous fire' from the Star Destroyer to break the shield, and this page suggests that the turbolasers firing the medium-length turbolasers have the ability to fire one shot every two seconds. Can the Reapers fully restore their shields every two seconds?

The only estimates I can think of off the top of my head can be found here and here. The first page suggests that 1e20 Joules is a reasonable estimate of the energy required to break an Imperial Star Destroyer's shields and 3e20 Joules is a reasonable estimate of the kinetic energy required to do the same, though the former value is absorbed over ~30 minutes of engagement and the latter is suggested to be absorbed over the course of 1-2 days. The second page suggests that a shield which was probably already depleted to an unknown degree had an instantaneous impact absorption capacity on the order of 5e14 joules, and sites a book (Anakin Skywalker: The Story of Darth Vader) as stating outright that Star Destroyer shields in peak condition are capable of absorbing multimegaton impacts, though I think the book in question is no longer canonical as of whenever it was that Disney threw out the EU.

If you were to assume that all the weapons on the Star Destroyer fire medium-length bolts each capable of delivering 30 TJ, that each Star Destroyer is capable of firing 5 shots per second (time averaged rate of fire against the Tantive IV in A New Hope, though the Star Destroyer int that engagement may not have been employing all its guns to the fullest extent as the objective of that engagement appears to have been to disable the Tantive IV rather than destroy it), that Star Destroyers and Mon Calamari Cruisers such as used at Endor have comparable firepower, and that each Star Destroyer was engaged by one and only one Mon Calamari Cruiser (which directed all 5 of its 30 TJ shots per second at the destroyer), then in order for the Star Destroyers to be able to engage the Mon Calamari Cruisers for ~30 minutes before shields began failing the Star Destroyer's shields must be capable of absorbing at least 2.7e17 joules over 1800 seconds (30 minutes) before failing. Another estimate of the shield power you could make involves the assumption that the Imperial Star Destroyer is a 'balanced' warship (i.e. a warship whose defenses are capable of resisting its own armament). According to Wookieepedia's Imperial-I Star Destroyer page, an Imperial-I Star Destroyer should carry at least 91 turbolaser cannons. If we assume that 40 of these can be brought to bear for the 'resists its own armament' test (and I would suggest that ~50% of the ship's armament being brought to bear against a single target is something akin to a lower bound on the ability of a Star Destroyer to concentrate its weapons on a single target), then using the 30 TJ per bolt figure an Imperial-I Star Destroyer's shields should be capable of absorbing at least 40 30 TJ bolts impacting roughly simultaneously, or about 1.2e15 joules. If we instead use the 250 TJ figure for vaporizing the asteroid, then the Star Destroyer's shields should have an energy capacity of at least 1.0e16 joules.

As far as how well the Star Destroyer can resist the fire of the Reapers, the main weapon of a capital ship type Reaper is stated to have a yield of 132 to 450 kilotons of TNT, or 5.5e14 to 1.9e15 joules (source). If Star Destroyer shields are as effective against kinetic impactors as they are against turbolasers, then using the lower bound for 30 minutes of combat and assuming that Star Wars shields do not recover over time, an Imperial Star Destroyer's shields should be capable of absorbing 142 to 491 shots from the main weapon of a capital ship type Reaper. Using the 30 TJ per bolt figure for turbolaser bolt energy, a Star Destroyer's shields should be capable of absorbing about 1 to 2 shots from the main weapon of a capital ship type Reaper; the 250 TJ per bolt figure for turbolasers would indicate that the Star Destroyer's shields can absorb about 5 to 18 shots from a capital ship type Reaper's main weapon. I would tend to expect that the Star Destroyer's shield capacity is somewhere between the first estimate and the second if the 30 TJ per bolt figure is to be used as the energy carried by a turbolaser blast regardless of the type of turbolaser used and the likelihood that this is less than the actual amount of energy carried by each medium-length turbolaser bolt.

It would appear from the information provided that if we are generous to the Mass Effect Reapers then the Reapers might be able to take down a Star Destroyer's shields in one shot and then destroy the ship with a follow-on shot. If we are less inclined to go with minimal estimates for Star Destroyer shield capacity, things get worse for the Reapers very quickly.

It might be that Death Squadron could do so but that doing so would make it unlikely for anyone to survive the bombardment. Vader's objective at Hoth isn't entirely clear; he wants to destroy the rebel forces, yes, but he also wants to capture Luke and may also want to capture some of the higher-ranking rebels. If the Star Destroyers are capable of a high-accuracy long-range bombardment to destroy the shield generator, hangar bays, and major defensive emplacements, the apparent plan of bombarding the world from outside of the system is not inconsistent with capturing high-value rebels. General Veers' statement that the shield is capable of 'deflecting any bombardment' makes that a questionable interpretation, though it's still possible that there was an implied qualifier on 'any bombardment' of "that allows a reasonable chance of fulfilling the 'capture high-value rebels' objective." General Veers was told to prepare his men for something even before the fleet moved to the Hoth system, Vader is known to be interested in Luke even at that stage of the movie, and later events strongly suggest that the interest is 'capture' rather than 'kill,' which all suggest that the objective of the originally planned orbital bombardment is the disabling of major defenses and the closing off of potential escape routes (destroy hangars, hangar exits, exposed vessels) rather than simple base destruction.

As far as why Rebel warships do not carry shields of the same power, why do you feel that Rebel warships (or, for that matter, Imperial warships) have the necessary power available for that? The Hoth base's power generators are only known to have two major power drains -  the theater shield (and much of the base's power should have been redirected to this, according to dialogue in the movie) and the anti-orbital ion cannon. The Hoth base may also have a much larger power source than an average Rebel (or Imperial) warship; Wookieepedia's page indicates that the theater shield was powered by the reactor out of a Praetor-class battlecruiser according to the old expanded universe material, where a Praetor-class battlecruiser was a ship type about 2.5 times the length of an Imperial Star Destroyer and only about ~30 years old at the time of the Battle of Hoth (it was developed in the "final years of the Old Republic," i.e. around the same time that Imperial Star Destroyers began appearing; it may be a design generation or two older, but probably not much more than that). If this is still canonical, or at least representative of the reactor(s) used in the new canon, the base should have had significantly more power available than most of the Mon Calamari Cruisers and Imperial Star Destroyers; Executor and Home One are the main exceptions (along with a couple unidentified potentially large Mon Calamari cruisers which took part in the Endor engagement), and unlike the base those vessels also need to power a significant number of heavy weapons which may be firing at a significant rate for an extended period of time (the base generator(s) powered only a single heavy weapon which fired infrequent bursts of several shots, though it's difficult to assess whether or not this represents a similar, greater, or lesser demand on the available power). The base may also have been able to make use of higher power levels for notionally similar components due to the superior cooling offered by an atmosphere as opposed to vacuum, though at the power levels apparently involved in Star Wars I doubt this would make too much of a difference.

And yet they are not sufficiently advanced relative to the 'new' players on the field to be effectively invincible. The margin of superiority enjoyed by the Reapers is only such that the capital ship type Reapers can engage ~3 capital ships of the species present in the era in which the game is set. These species have only been capable of interstellar spaceflight via mass relay for ~3000 years at the outside, and a species which should have been ~1000 years behind in technology was able to at least compete with the empire with the biggest military. A guy with a club is still a threat to a guy with an assault rifle (though not in most scenarios that aren't fairly contrived), but both of them are very little threat to a guy in a tank, and the Reapers ought to be the guy in the tank with millions of years to develop while the new players on the field are the guys with the club (really recently arrived at interstellar spaceflight) or rifle (older species capable of interstellar spaceflight). They aren't, and while part of that can be attributed to the accelerated development due to the existence of functional relics, your sciences need to be similarly advanced before you can begin to understand even a functioning relic, and your technology and industry needs to be similarly advanced before you can begin making use of anything you learn from that. This means that as far as ancient civilizations go, Prothean and Reaper technology is fairly low-level stuff; Prothean stuff can be understood well enough by species with in-system spaceflight capability to permit those species to reverse-engineer the relics and apply the technology thus developed with little lead time for improving the existing industrial base and overall technology level, and Reaper tech can be understood well enough by species which are so little advanced beyond the initial 'mass effect' discovery that a species which made the discovery within the past couple decades at the outside is militarily competitive with a species that made the discovery a thousand years earlier and which is allied with at least three other species which made the discovery at a similar point or up to ~2000 years before they did that studies of it produce usable results within a few years. Reapers are furthermore insufficiently advanced beyond these that they are vulnerable to the weapons used by these comparative newcomers even without any of the advances gleaned from study of examples of ~modern Reaper technology (as opposed to the presumably older technology represented by the mass relay network, the Citadel, and the stuff that the Reapers do not cleanse during their purge of the galaxy). Some showing for this group that's been around for millions of years when it's facing groups which have had less time to develop by a factor on the order of a thousand or more.

So... based on your expert opinion (and yes, you are an expert) it would be close to an even fight, but with the advantage given to the Star Destroyers? 

How would the two compare against Federation class Starships from Star Trek? 

Your saying so does not make my opinion expert, and I would only call it close to an even fight at the very low end of the power range estimated for a Star Destroyer. If we're talking about a campaign rather than a duel, then Reapers are no match because their FTL system is many orders of magnitude slower than the Star Wars hyperdrive (or, for that matter, the Star Trek warp drive, which itself is so much slower than the Star Wars hyperdrive that even assuming parity in weapons and defense systems the Federation would be screwed) except perhaps between very specific predetermined points.

As far as whether or not Federation-class starships would be capable of facing off against a Star Destroyer, I am rather doubtful. However, as far as I am aware, no Federation-class starships have ever been seen; the only mention of them that I am aware of is in The Search for Spock. Due to the paucity of examples of their capability (as in, there are no examples of the vessel's capabilities of which I am aware), I'll not comment on the Federation-class dreadnought's capabilities aside from saying that the technological capabilities of the United Federation of Planets appear to me to be significantly inferior to those of the Empire, including in weapons and defenses and so I would not expect the Federation-class to be worth much of anything, seeing as it's a TOS-era vessel and thus presumably less powerful than equivalent TNG-era vessels.

The winner would be the one whose magic you most believe in.

I think this could only be solved by a cage match between George Lucas and Gene Roddenberry, but unfortunately that can't and won't happen.

http://www.youtube.com/watch?v=ZaB_G1WNT70&t=0m52s

Yea I always thought it was very dumb how the reapers were just super advanced in-spite of having had millions of years to harvest countless races for their tech. It's even more dumb that their original creators have just been hiding in a cave this whole time and still for some reason don't seem to be any more advanced by the time the games take place then they were originally.

It was sort of addressed in game by what the Reapers were and how they operated.  They left Mass Effect technology so that everyone else would use it and trap them to a predestined progress in terms of technology.  The Reapers of course know it better and therefore come in and can deal with everyone else.  While everyone else also  find out that this miraculous technology that was left sitting around for them to use was actually just a trap to set them up to be reapered. 

So while the Reapers have been around for an unknown amount of time they haven't needed to advanced because they don't need to nor is it their goal.  Their goal was to  to preserve organic life from AI lifeforms by killing everyone and turning them into machines...which still makes no sense at all.

wow ... stardestroyer.net still around? Waves to Mike Wong.

1e20 for an ISD's shields is completely bogus if where using EU evidence. We've seen proton torpedoes go off in atmosphere and it's arguable if they reach even 10KJ equivalency. We know from the same EU that to knock out all 6 shield facings takes roughly 120 torpedoes. That's only 5.4E15. Even if you fudge the proton torpedoes up some anything north of 16 zeroes is unreasonable. And we've seen ISDII's pound each other for 10's of minutes before going down. So the weapons don't hit that hard.

Official armament of an ISDII from EU is 64 turbolasers and 20 Ion cannons cira ROTJ. They have a bunch of smaller guns as well but they're considered chaff in the wind in a capital engagement.

I'd say you're almost there.  The mass effect tech used by the Reapers is more advanced than anything the galaxy's races had, and the Protheans had only begun to build their own versions (the Conduit) when they were culled.  The tech used by the Reapers isn't underwhelming because it can be overpowered by new races massing their attacks, the new races' massed attacks are overwhelming because they are using tech decades or centuries beyond their level.  And also, the Reapers haven't needed to evolve.... much.  However, they show the ability to adapt.  When Sovereign discovered the Keepers would not respond to their signal, it indoctrinated the Rachni race because they were the next best tool for the job.  The Catalyst even said that adaptations had to be made for the ways organics kept changing.  Not that one can attribute true scientific advance to the Reapers as a faction, but changing tactics and exploiting weakness is nothing new to them. 

I would also call into question the terminology used in the SW material.  Estimating the turbolasers at 30 tj is based on the vaporization of asteroids in ESB.  I am inclined to throw this out the window, tbh, given Lucas's penchant for changing his movies and the special effects therein, and the effect limitations of the original filming.  While the energy requirements cited to perform a feat such as vaporizing an asteroid are accurate, the delivery is insufficient; to produce the effect seen in the movie, a TL shot would have to be as wide as the asteroid in question.  As said on the source page itself, rock does not transfer heat energy that fast; the energy required delivered in a beam the diameter of a TL barrel would result in an asteroid belt full of rocks with holes all the way through.  Simply put, vaporizing and asteroid simply wouldn't look like it does in the movie. 

Melting an ice moon is likewise questionable- ices include methane and ammonia, and other things less common in the universe, that can freeze in the cold of space and often only at temperatures much lower than 0C.  Introducing sudden terrible heat to a seemingly inert frozen mass can set off all kinds of hyperexpansion and vapor explosions that can rend the whole body apart, especially if some parts underneath are only solid due to pressure. 

The ability of a ISD to reduce a planet's surface to slag is, as well, very open to interpretation.  Given the prevalence of the term used as shorthand for any orbital bombardment badass enough to really ruin somebody's day I don't think it's worth doing the calculations for... although I have to give the guy credit for crunching those numbers in the first place.

There is also the matter of the ISD shields.  They are measured as absorbing electrical energy, yes, but while they can take an energy barrage they don't do so hot against solid mass impacts.  Back to the asteroids- those guys aren't just blowing apart rocks for kicks.  It's stated that the field is a very real and persistent danger to the ships, and in the scene where Vader is talking to the other ship captains, one of them looks off to the side in horror and surprise before suddenly disappearing, with the insinuation that his ship (or at least his bridge) has taken critical damage very quickly and with little warning- ie, a single asteroid.  I would wager that an ISD might be able to deflect the PD beams a Reaper carries (if they are laser-based) or perhaps a Reaper's swarm of Oculi drones (if they fire lasers instead of particle beams or something), but against a concentrated stream of molten metal traveling at an appreciable fraction of the speed of light?  Now you're talking heat energy (which can still cook an ISD through the shields, otherwise Thrawn's gambit in the second book would not have required enough plate armor to blind the ship in order to pull off) and kinetic energy (which is already shown to be able to punch through the shields), and electrical energy shielding won't help. 

And that is assuming the ISD gets close enough.  In the original X-Wing space combat game, standard engagement range for an ISD was about 1.7 kilometers, if I remember correctly.  Well, anything with a turbolaser weapon, that is- including Nebulon frigates and Calamari cruisers.  Reapers are said to outpace a ME dreadnought in every way- even if we assume range is the one variable excluded, that means the Reaper will begin its barrage at 2000 kilometers or more, and the ISD still has quite a distance to go.  Yeah, so, that's a pretty bogus number and a bad reference.  I suppose even though it's Lucasarts canon, they had to take some liberties because of the medium.  Must be like those "vaporizing" asteroids in ESB.  In any case, unless someone has range figures on a turbolaser (since mine is obviously bunk), let's assume that since an ISD can bombard planetside with its TL batteries it can do so from space.  Low earth orbit (where the ISS currently is) is about 450 km up.  While the ISD blockade around Hoth was much farther out than that, they were not bombarding the planet; on the other hand, the planet-based heavy ion cannon COULD hit them with devastating impact, and remember it was powered by a generator for a ship not much larger and not much older than the ISDs it was hitting.  It can be assumed without too much trouble that an ISD's absolute range would overshadow a Reaper.  However, TL bolts have an embarrassing travel time, can be seen coming, and can be dodged even by stone-age teddy bears, and Reapers are much more nimble in sublight travel than the hulking ISD.  Meanwhile, the Reaper's main weapon tends to hit pretty straight and true nearly all the time.  So while the absolute ranges look to be in the ISD's favor, the practical ranges appear to very much be to the Reapers.  ISDs are said to use their smaller TL batteries against fightercraft because of how fast they can move in combat, relative to the ISD- that's tangential velocity for those of you not playing EVE.  Reapers have the drives to alter their tangential velocity quickly and by large degrees, and a high top speed.  ISDs are fast, but obviously cannot track fast targets and they can't turn anywhere near as quickly as a Reaper.  I would almost question whether an ISD would be able to land a hit with its main cannons if the Reaper didn't want it to.

That isn't even getting into the issue of Oculi drones vs TIE fighters, given that Reapers practically manufacture the things and ISDs seem to be pretty vulnerable to massed small craft assaults. 

SO... a Reaper outranged by an ISD, adopts tactics to evade the heavy batteries, closes in to return fire, continues to evade, and the ISD sits there taking the hits until it's destroyed or its crew is indoctrinated.  I would imagine Oculi and TIE fighters nullifying each to be very charitable to the Empire, given how weak TIEs are and how accurate Oculi are. 

1. The EU has been tossed out, and was never a particularly reliable resource anyways.

2. The only time that torpedoes have been employed against something which might generously be called a capital ship in the movies, the torpedoes had no apparent effect upon the target, an armed merchant freighter (granted, supposedly one with relatively strong defenses). At no other point in the six live action movies were missiles or torpedoes employed against capital ships when there were other weapons available. This strongly suggests that torpedoes are far from capable of bringing down Star Destroyer shields entirely with a mere 120 torpedoes. Beyond that, Proton Torpedoes and Concussion Missiles are supposedly roughly as powerful as one another; the Victory-class Star Destroyer, supposedly armed with 80 Concussion Missile Launchers, is regarded as a second-class capital ship at best by the same EU writers who write of mere tens of missiles and torpedoes first penetrating the shields of and then gutting Imperial Star Destroyers.

We never once see torpedoes employed en masse against capital ships by any group which has an available alternative, despite the supposed power of the weapons in EU sources. We never once see capital ships which are stated to carry torpedoes as part of their armament employ torpedoes against similarly large vessels (Venator-class Star Destroyers are supposedly armed with torpedoes in addition to their turbolaser armament, though it's a mere four tubes with 16 torpedoes each on a ship over 1.1km long when a 12m ship can carry two torpedo tubes and six torpedoes, according to Wookieepedia; the capital ship instead is primarily armed with turbolasers and laser cannons). We hardly ever see fighters employed as the primary attack units against capital ships, except when capital ships are unavailable for the purpose, yet according to your figure of 120 torpedoes to completely down a Star Destroyer's shields the Rebel fighter force should have been a very dangerous threat to the Imperial fleet at Endor; this is not in evidence. Fighters instead primarily engage other fighters and strafe capital ships occasionally; when they do attack capital ships, they furthermore do not employ torpedoes and instead use their laser cannons, despite these torpedoes supposedly being so powerful that a single torpedo ought to be comparable to many minutes of continuous fire from a capital ship.

In short, the EU writers who made up the figure of 120 torpedoes to down a Star Destroyer's shields are full of shit, and made up the figure so that they could have their starfighter-focused stories which largely focus on independent operations of small groups of fighters engage an iconic Imperial warship from the Star Wars movies without bringing capital ships into the story. Video games are another part of the EU which commit this offense, often having fighter torpedoes and missiles bypass shields and cause enormous amounts of damage to the target despite the utter lack of support in the six live-action movies for missiles and torpedoes having that kind of power.

Did you actually bother reading the linked page? 30 TJ is based on melting the asteroids in ESB, and furthermore is based on melting small asteroids in ESB, not vaporizing them. The vaporization figure is 250 TJ per bolt, and moreover is more likely given the behavior of the asteroid upon being struck.

Furthermore, if you are inclined to throw the movies out the window, what possible source material could you accept? The movies are the most canonical source of information on Star Wars, much like the Star Trek shows and movies are the most canonical source of information on Star Trek and the Mass Effect games are the most canonical source of information on Mass Effect. Throw the movies out the window and you're left with nothing but baseless assumptions.

Numbers from video games are something I would rate beneath even many of the written works in the EU for accuracy. Star Destroyers at Endor clearly began to engage well beyond the 1.6 km mark; you only see warships in such close proximity after the Death Star begins targeting Rebel capital ships and the Rebel fleet closes with the Imperial fleet to make the Death Star less likely to be able to get a clear shot.

Beyond that, if we take literal interpretations of dialogue within the movies to be canonical information (a position not dissimilar to that of those who argue that dialogue in the Star Trek programs is an accurate source of information on the capabilities of Star Trek technology), then the 1.7km engagement range of a Star Destroyer is completely nonsensical. Darth Vader's dialogue in The Empire Strikes Back is clearly indicative of an intention to bombard Hoth from outside the system boundary (the fleet emerged "too close to the system ," not too close to the planet), indicating that the weapons of the ships have sufficient accuracy at that range to bombard a planet from several light-hours at minimum. Furthermore, since Vader clearly desires to capture Luke and since General Veers is ordered to prepare his troops for something prior to the fleet even arriving in system and the rebel shield going up, it is unlikely that this bombardment is an inaccurate blanket bombardment of the planet's surface but rather a targeted bombardment which is intended to destroy power generators, shield generators, hangars, hangar exits, and significant defenses. While this is likely an easier feat than engaging a maneuvering warship, it is unlikely that a maneuvering warship is so much more difficult to hit that the effective combat ranges are reduced from several light hours to a mere ~2 kilometers.

Furthermore, I see no reason whatsoever to accept video game figures if behavior evidenced in the movies is to be thrown out the window. Toss out the most canonical source of information yet accept information from one of the least canonical sources, and one of the sources most likely to bend figures simply to make the game work?

And your evidence for the Reapers being capable of evading turbolaser fire is ... what, exactly?

Your entire position is essentially "I don't like the numbers that come out of analyzing the source material or which are stated to be valid for the source material. I will therefore make up my own canon and ignore everything that doesn't agree with me as well as make up 'facts' to support my case (such as the Reaper ability to evade turbolaser fire)." This position is, simply put, an unreasonable basis for any form of rational analysis. Yes, there are flaws with the source material (for Mass Effect, for Star Trek, and for Star Wars). Yes, not everything in each source makes perfect sense under current real-world physics. However, if you are to compare any two settings, you must accept either the numbers stated for the setting or the numbers which come out of analyzing the source material. You are throwing out the Star Wars movies in favor of the unreliable, questionably canonical material in the EU and in video games which play fast and loose with the numbers to fit game mechanics and to make the game enjoyable, simply because the numbers from those derivative products fits your vision better despite being at best a poor match to the demonstrable capabilities within the setting as shown in the movies.

I've actually read all of this debate with a good deal of interest.  The amount of detail is impressive.  Apparently Star Destroyers have massive amounts of point defense/ anti-missile capabilities to the point where the different sides don't even try.  And they're particularly vulnerable to kinetic attacks and their anti-beam defense is average.  Duly noted.  

Question, though: If YOU could design an imperial star destroyer, how would you do it? The goal is to create the most effective Star Destroyer (which raises the question of: effective against what?) using the least amount of resources possible.  

CAN a fleet of star destroyers take down a fleet of reapers? If so, under what conditions? If not, could they be designed to do so? And of course: vice versa.  

Joeball: the re-watch the original trilogy again, we see concussion missiles amongst other things used against capital ships at endor by the fighters. one of the execturors shield generators gets taken out that way. 

Also when i said 10KJ for proton torps i meant 10KT. *facepalm*

There is no evidence anywhere in the movies of light point defense weapons intended only for use against missiles and torpedoes. In the opening scene of Revenge of the Sith, we see some missiles fly relatively close to a capital ship without provoking a response from the supposed anti-missile point defense system which can down missiles so effectively that even the enormous missile density that capital ships should be able to launch would not practically penetrate the defenses. In the space battle scene at the end of The Phantom Menace, we see an N1 starfighter fire a missile against the Trade Federation vessel without provoking a response from the supposed point defense systems that render missiles and torpedoes useless; the missile impacts upon the ship's shields and causes no apparent damage, and dialogue indicates that the fighter weapons were completely ineffective against the ship's shields for the duration of the battle. This is a converted freigther that we're talking about, not a dedicated, purpose-built warship like a Star Destroyer, and it's under attack from presumably military-grade starfighters armed with presumably military-grade weapons.

Beyond that, if ships in the Star Wars universe carry a number of light point defense weapons capable of reliably downing large numbers of missiles, where are the intermediate weapons for use against starfighters at close range? We never once see a single large warship in the Star Wars universe employ a light weapon (i.e. something comparable in size to the weapons mounted by the fighters) against a starfighter; instead, we see relatively heavy weapons employed even at short range. This, combined with the demonstrated ineffectiveness of fighter weapons against a converted freighter in The Phantom Menace, the lack of use of fighters against capital ships except in a harassment role, the demonstrated ineffectiveness of fighter 'lasers' against shielded capital ships, all suggest that the reason that missiles and torpedoes are not employed against capital ships in the Star Wars universe is not that there is this wonderfully effective point defense grid protecting capital ships from missile and torpedo attacks but that the missiles and torpedoes employed by starfighters are simply not that powerful.

Furthermore, the one time we see torpedoes impact a capital ship's hull in the movies (the Death Star run immediately before Luke's run in A New Hope), we see that the damage inflicted by the torpedoes is at most on par with the damage inflicted by the fighter laser cannons. In other words, the apparent power of a torpedo is similar to the power of a starfighter's laser cannons, implying that if 120 torpedoes can take down a Star Destroyer's shields, so can 120 blasts from a starfighter's laser cannons, laser cannons which have been repeatedly shown to be ineffective against shielded capital ships. Yeah, I'm not buying the supposed power of fighter torpedoes.

Starfighters are capable of carrying these weapons. Starfighters are shown to be capable of evading what anti-fighter weapons heavy warships employ well enough for a reasonable number of fighters to survive long enough to get into close proximity to large warships. Starfighters are shown to be able to employ the missiles and torpedoes against the large warships with which they're in close proximity. Starfighters are also not considered enough of a threat to large warships for anyone, regardless of whether they're affiliated with the Rebellion or the Empire, the Republic or the Confederacy of Independent Systems, Naboo or Trade Federation, to care enough to install more effective anti-fighter defenses or, for that matter, to use starfighters to employ these supposedly quite powerful missiles and torpedoes to take down the shields of heavy warships from within the minimum effective range of this hypothetical point defense system that prevents capital ships from employing the weapons at longer ranges when there are other options, such as capital ships, available. Therefore, in all likelihood, starfighter missiles and torpedoes are not the superweapons that they're claimed to be in the EU, capable of downing Star Destroyer shields with only a few dozen hits or some such thing. The missiles and torpedoes might be relatively powerful for fighter weapons. There is very little evidence that they are anything like capital-grade weaponry, certainly not anything so greatly in excess of the power of capital-grade weaponry that a mere 120 missiles or torpedoes can completely strip the shields of a Star Destroyer.

I disagree. Nowhere do we see missiles or torpedoes fired in rapid succession in a manner similar to the stream of blasts fired by the A-Wings against the Executor's dome. Nor, for that matter, do the blasts look, at least to me, like the missiles or torpedoes we see employed elsewhere in the movie, nor do the sound effects while the A-Wings are firing sound, to me, like the sound effects used when the X-Wing and Millennium Falcon fire missiles or torpedoes within the Death Star.

So you're basically saying Star Destroyers are rather poorly designed? Or their passive defenses are so powerful that fighters on average are not a threat UNTIL the destroyers' shields are stripped away in a capital ship engagement? 

Which raises an interesting idea: a good idea to balance carriers is to make defenses a lot stronger than what the fighters can do.  

Also, make it so that as ship gets damaged during battle, its defenses weaken.  

'Poorly designed' is a misinterpretation. Something is not 'poorly designed' if it doesn't have weapons specifically intended to be employed against something which isn't a threat. Nor am I saying that the missiles and torpedoes are not a threat until the shields are taken down; rather, the missiles and torpedoes appear to be simply not a real threat at all to something like a Star Destroyer, barring specific weaknesses like the first Death Star's direct path to the reactor offered by the unshielded exhaust port. Look at what the torpedoes that hit the Death Star's surface did - apparently nothing. There is no evidence of damage to the Death Star's surface when we see Luke make his run and we see the area of the Death Star's surface around where the torpedoes impacted; certainly nothing beyond what the fighters' laser cannons were capable of doing elsewhere on the Death Star. Even if it is torpedoes that destroyed the Executor's dome, that appears to be a relatively soft target rather than a well-armored target like most of the rest of the hull would be.

Indications are that while the fighters' torpedoes may be somewhat more powerful than the fighters' laser cannons, they are not exceptionally more powerful. Certainly not to the point of being able to compete with capital ship weaponry in the manner suggested by requiring a mere 120 torpedoes to hit a Star Destroyer to completely strip away its shields.

I suppose I have to take this back. Wookieepedia claims that this was a torpedo volley on the Executor's page (Battle of Endor section), so I suppose I'll go along with them. I still don't think it looks much like torpedoes, though.