The Ultimate 304's Guide : Anything, Everything and Speculations about 304's

[Crazy Tom]

Actually, Battlecruiser is fairly accurate: Asgard hyperdrives and plasma weapons mean that what it can't outgun it can outrun. It do4es mount the most powerful engines and weapons, just like a battlecruiser, and honestly, how many times have the fighters actually killed another ship?

[Setiform]

This is kinda a new topic but is the 304 a battle ship of a fighter ship? If you compare the battle abilities of the 304 to a traditional warship of the sea then then don't seem to line up. For example, a warship can defend itself from all sides with rotary cannons. Translated into space that would mean the the 304 would be able to fire backwards and forwards at the same time, providing a full sphere of fire. What we have seen from the show is that the 304 only has fire batteries at the front firing forward in about a half sphere of fire like a fighter jet. This would make the ships title of BC or battle cruiser inaccurate. Just some thoughts. i'd like to know what you think.

But there is a very good reason why you don't want to shoot backwards and I could just tell you, but it wouldn't half as much fun as proving it! ;-)

To answer the question, we first need to know a few things, like just how fast is sublight, how fast are the railgun projectiles and how fast is the target you're shooting at?

But first, let's deal with sublight. It's slower than light speed, yes, but by how much? We need references! But the writers aren't stupid. They've always been very careful to not have any real figures used. They just say things like "sublight is too fast" or "sublight is too slow."

But now and then, they leave a clue...

Recall the season 1 Atlantis episode, The Defiant One. A puddle jumper makes a journey lasting 15 hours to reach the defence satellite and the nearby uninhabited planet on which there is a crashed Wraith ship. But that doesn't tell us how fast the jumper was travelling or how far away the satellite/planet are. But the environment of the planet could give us a clue. It was desert, but not arid. There was a water vapour atmosphere and signs of animal life and vegetation, although not much. As I watched the episode, I remember thinking it might be a wetter version of Mars.

You might have heard of the phrases "the life zone" or "the green zone." This refers to the distance region around a star in which the temperature is moderate enough to allow life. Mars is at the outer edge of the life zone in our solar system. Venus is at the inner edge and Earth is, happily for us, right in the middle. But if Mars were a little closer in, perhaps it would look like the planet from The Defiant One?

So how far is that? The closest theoretical distance between Mars and Earth (that is, if you lined up the Sun, Earth and Mars and drew a straight line through them) is 54.6 million km. We want to bring Mars in close enough to get warmer and wetter, so I'm going to arbitrarily divide that figure in half. That gives us 22.3 million km.

Why is this important? Because I'm going to assume that Lantea orbits a star similar to ours and has a similarly sized life zone surrounding it. I'm also assuming that 22.3 million km is close enough to get a livable desert planet that humans can survive on the surface of. Therefore, it gives us the distance the puddle jumper travelled to reach the planet!

Now it's just a case of dividing 22.3 million km by 15 hours to get 1,486,666 kph, or 0.13% of the speed of light!

I was actually pretty pleased with that. 0.13% is a very realistic figure. I was expecting something much higher. Perhaps the writers knew what they were doing after all! ;-)

So, given that we know a 304 can fly as fast as a puddle jumper (plenty of on-screen evidence for that), we now know that a 304 can fly at 1,486,666 kph, but to keep things simple, I'm going to use the figure 1,500,000 kph instead.

Let's assume that in the stargate universe, everyone likes to fly at 1,500,000 kph when at sublight and that this is a typical speed for ships engaged in combat.

Hypothetical situation: the Daedalus exits hyperspace, whereupon you discover a Wraith cruiser waiting for you. They get off a lucky first shot that cripples your Asgard beam weapons, forcing you to rely only on your rail guns.

So there you are, flying towards the cruiser at 1,500,000 kph and you open fire with the forward rail guns.

What happens?

Here I run into a problem, because Colonel Everett from The Seige said that the railguns fired projectiles at a velocity of Mach 5, but mach numbers have no dimension. As the dictionary defines it, a mach number is the ratio of the speed of an object to the speed of sound in the surrounding medium. So the speed in kph of mach 1 will vary according to atmospheric composition and temperature. But in outer space, such a figure is utterly meaningless, so what did Everett mean? I'm going to make an assumption that the Colonel meant 5 x speed of sound in Earth's atmosphere at sea level on a cold day (the so-called Standard Day that is used to calculate mach ratios), which is approx = 6,125 kph.

So, you're firing the forward rail guns at the Wraith cruiser. The rail gun projectiles (call them bullets) will have a velocity of 6,125 kph + your sublight speed, so that's 6,125 + 1.5 million = 1,506,125 kph.

Your bullets will hit the cruiser at more than 1.5 million kilometres per hour!

But what if the cruiser takes up a position broadside to broadside (which seems to be a popular tactic among the Wraith)? In other words, what if he matches your course and speed? Then your railgun bullets lose the benefit of the Daedalus's own velocity and your bullets are striking him at "only" 6,125 kph (hmm... perhaps there's some sense to this Wraith tactic after all!)

Now, finally, the relevant part. The part that answers the question!

What if the Daedalus accelerates away from the cruiser, putting the cruiser behind the Daedalus? The Daedalus flies away at 1.5 million kph and shoots backwards. The railgun bullets are leaving the muzzles of the railguns at 6,125 kph. What happens?

Well, unfortunately, the Wraith are laughing because your bullets are going nowhere. All you've done by firing them out of the railguns is slow them down by 6,125 kph. Your bullets are now travelling in the same direction as you (that is, away from the Wraith) but at a slightly reduced speed of 1,493,875 kph. The only way for them to hit the cruiser is if the Wraith chase you and accidently fly into the bullets but even then, because the cruiser is already travelling at 1.5 million kph (sublight speed) the bullets would only collide with the cruiser at 6,125 kph. And this would be very unlikely to happen because the Wraith would have to be pretty stupid and very bad pilots to allow themselves to collide with a cloud of relatively slow moving space debri. After all, they fly around in space all the time without hitting things like asteroids, so why would this be any different?

The only way to do damage to an opponent who is behind you is to shoot a bullet that is moving much, much faster than you are. The railguns would need to have a muzzle velocity of much more than 1.5 million kph because the bullets would have to decelerate to 0 kph then accelerate towards the cruiser. This is called passing through zero velocity and it's a killer! You need a lot of energy to shoot things backwards, because you've got to cancel out your own forward momentum and then still have enough energy in your bullet for it to carry enough speed to do some damage.

Bottom line: if you fly away at 1,500,000 kph and shoot the bullet backwards at 1,500,001 kph, it will pass through zero velocity and then hit the cruiser at exactly 1 kph. Can you hear that? It's the sound of Wraith laughing.

So, in conclusion, the best possible way to attack the cruiser is to accelerate towards it at sublight speed and then open fire. The second best way (but not the way you would choose if you had a choice) is to match course and speed and slug it out, broadside to broadside, but you lose all advantage of having those big engines on the back of your 304.

The worst possible way to attack is to run away! ;-)

And that is why spaceships in science fiction movies don't shoot backwards... most of the time, anyway :-/

It is interesting to note that this "zero velocity" problem also applies to the ships fighters! The fighters can only fly towards targets that are ahead or parallel to the mothership. If they try to turn around the fly towards a target that is behind the mothership, they must have enough fuel/energy to decelerate to 0 kph (to shed the momentum of the mothership which they carried with them when they were launched) and then accelerate back up again to fighting speed. After the battle is over, they then have the problem of how to catch up to the mothership again, because either the 302s or the 304 must turn around and decelerate, so you can see that it starts to get very expensive in terms of fuel consumption. You don't get many miles to the gallon in this game!

[lord groovy]

When I read the first lines of the previous post I thought you would just say that anything behind a cruiser would be fried by its humongous engines. They are powerful enough to serve as weapons.

I think it's related to something called the Kzinti Lesson. I've seen it on another thread when talking about Avatar and the device use to launch the transport ship from Earth to Pandora. That was an array of Laser stations around Mercury producing a 100times more energy than today Earth annual consumption and this for the a very short time. Enough to discourage any alien invasion attempt (or well any Earth or Mars rebellion)...

[deltaCain054]

I think I accidentally replied to Setiform like twice so sorry if I did. I meant to post it here.

Love how you put science behind everything. The only problem I saw was tactics. while the 304 is easily capable of 15 million kph, in combat against a single ship its unlikely they would go even a quarter of that speed. In space high speed means less ability to evade and maneuver. Second while the hive ships tend to make broadside attacks, the cruiser would not. It is designed for speed and maneuverability, with by far less armor. A cruiser would attempt attacks from odd angles, never making an attack directly at the304. To do so would mean less ability to evade and cause the rail guns to do increased damage. Third its unlikely you would ever be able to make a head on attack on a cruiser with a 304, unless they were on a suicide run.
So even if they (the wraith cruiser) are behind you (the 304) they would be relatively close (at long range you can simply turn around) and matching your speed relatively so the rounds would hit with their relatively normal speed. As far as hitting it is concerned the targeting system is more than capable of tracking and hitting the cruiser at short range.

As far as zero velocity problem with fighters goes: Its not necessary with a 302. The 302 is a high velocity fighter. It is designed to fight and maneuver high speeds, not stop on a dime. It would take less time and effort to simply make a wide arcing turn (shifting the momentum, not removing it). This would also give the pilot added time to maneuver and plan attack runs.

[Puddle-Jumper]

Id love to have seen an episode similar to Grace under pressure, but with the crew in a sinking 304, it crashes to a planet under wraith/ori fire and they have to escape as it slowly fiills with water.. I know they had it before with the Ha'tak but still it coulda been awesome!

[Cmdr. Setsuna F. Seyei]

@ Setiform
You forget to take one thing into account in your above lecture. in atmosphere you have friction while in space you have little to no friction which is why if you nudge something in space it will continue in the direction it was pushed until it is stopped. this gives the rail guns a much higher velocity when being fired outside of the atmosphere because the rounds dont have to contend with the slowing effect of friction.

[Asgard Flu]

Not really read the thread but the idea of using a Daedalus class ship as a midway station is silly, if the wraith managed to gate on the ship and take it over they'd have their hands on a powerful warship with advanced technology.