Author Topic: Railguns in Stargate vs. reality  (Read 4240 times)

Offline TNC

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Railguns in Stargate vs. reality
« on: July 03, 2014, 12:16:27 PM »
So I was doing some railgun research on the Stargate wiki for my fanfic.  According to the wiki, the railguns seen on the show (at least the ground based units seen in ATL: "The Siege") have a range of 250 miles and a muzzle velocity of Mach 5.  Now lets compare that to a common air-to-air missile, the AIM-120 AMRAAM (which has been stated as the standard armament of the F-302).  It has a range of 34-112 miles (depending on the version) and a top speed of Mach 4.  The railguns have nearly twice the range of the missiles and are faster, though the missiles have the advantage of being self-guiding.

Now for the range of the Stargate railgun.  The International Space Station orbits at about 260 miles.  That's right the railguns in Stargate would almost be able to reach the ISS from the ground!  And further, low Earth orbit is defined as between 99 and 853.8 miles above the Earth.  So these railguns could take out Goa'uld, Wraith, or Ori fighters within the lower thermosphere.

When I first started piecing all this together, I thought it was a case of "Sci-fi writers have no sense of scale".  So I started looking at what the experimental railguns being worked on today are capable of.  According to Wikipedia, the U.S. Navy wants to mount railguns on ships by 2016.  These would have a range of 100 miles with a muzzle velocity of Mach 7.  So the Navy desires a weapon that has a higher muzzle velocity than the Stargate railgun but with less range.  As of 2008, test units were capable of Mach 7 speeds.  Some experimental versions could theoretically achieve range of at least 230 miles and a muzzle velocity of Mach 17 when production ready!

So, in the end Stargate's railguns seem to have reasonable capabilities as far as comparing them to what real world test units are capable of.  Of course, I don't think the railguns in Stargate were ever used at their stated maximum ranges, much like Star Trek ships always duke it out at near point blank range despite having weapons with thousands of kilometers ranges.
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Offline Jimi James

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Re: Railguns in Stargate vs. reality
« Reply #1 on: July 03, 2014, 02:20:10 PM »
I've done similar research for New Haven, particularly in terms of scale/distances versus achievable speeds.  Particularly in space, where gravity and wind resistance are removed, you're range becomes even greater.  Technically, there's no reason why you couldn't shoot at targets that are thousands of kilometers away.  The problem is that when you start getting into distances that far away, even at high mach speeds, you're no longer shooting at where your target is, but rather where it's going to be, at least to your best guess.  If the lead time is great enough, then your target has the chance to actually see the projectile coming and get out of the way. 

So in some ways, missiles might be better because they can follow the target, but then you also run into the issue of how much fuel the missile can carry.  And like the rail gun situation, if you have enough lead time, the time between when the missile is fired and when you predict impact with your vessel, then you can try to outrun the missile or out maneuver it by making enough course corrections that the missile expends all of it's fuel trying to keep up with you.

That being said, all of this becomes less of an issue when you're dealing with ships that routinely fight at near point blank range, with energy weapons, and have energy shields.  It might be something to consider when writing about fighter engagements, though in the case of fighters, you're definitely going to be up close to range will likely matter even less.
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Offline TNC

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Re: Railguns in Stargate vs. reality
« Reply #2 on: July 03, 2014, 03:04:33 PM »
Well there's the option of rocket assisted projectiles with guidance (IIRC there are GPS guided, rocket assisted artillery shells in active service) for the railguns.  Then you've got a railgun fired missile of sorts, but that would still have the same issues you refer to for missiles at great ranges.  I guess in the end it comes down to maximum range vs. effective range.  As an aside, this reminds me of something I was reading regarding snipers and all the things they have to take into account for, basically saying that snipers are scary not because of shooting but because they've weaponized math.

There's also the argument of firepower of railguns in Stargate vs. reality, the article I linked to earlier mentions that some experimental railguns are comparable in firepower to Tomahawk cruise missile.  We know how fast the Stargate railguns projectiles are, but since we don't know what they are made of and how big they are we can't do the math.  The best guess for projectile size I have looking at the pictures of the ground based units would be in the 20-30 mm range (though that's only projectile diameter, we'd need length too).  As for what they're made of, I would guess they'd be tungsten or some other similar high-density material, possibly alloyed with one of those fancy alien elements like trinium or even naquidah. 

All we can really say definitively on the matter of firepower of the Stargate railguns is that they're pretty much useless on shields and Wraith ships must be made out of some really dense material to withstand the countless railgun slugs they routinely take.  Its not necessarily surprising that railguns are useless against shields considering we've seen Ha'taks take multi-megaton nukes to the face without even flinching.  With the Wraith though you would expect to see some sort of impact on the hulls from the projectiles, even though I don't remember ever seeing the slugs impact on the hull in the show.  I suppose they could be too small to notice, or perhaps the projectile is strong enough that it passes through a portion of the hull before being stopped.  Then it just comes down to how vital systems are arranged on the ship as to why they never seem to do much with the railguns.
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Offline Jimi James

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Re: Railguns in Stargate vs. reality
« Reply #3 on: July 04, 2014, 08:31:11 AM »
Yeah, in regards to the Railgun versus Wraith ships...do we know if the railguns used aboard the Earth ships are the same caliber as the ones that were used during the Siege.  If so, it's hard to imagine that they would do much damage against a well shielded target, particularly against the large Wraith cruisers and warships.  The darts would no doubt be susceptible to those smaller rounds...putting a 30mm round through the body of a craft that size is going to cause some problems, but on a larger ship, it'd be like trying to shoot down a fighter plane with an M-16.  Sure you might actually hit your target, but you're likely not going to do enough damage to slow it down.

I would imagine that the railguns on board a ship like the Daedalus, would be much larger, even potentially up to the size of a modern main battle tank round, in the neighborhood of 120mm.  I'm not sure how a turret that size would work though.

Slightly off topic, but you might find some useful information in the Halopedia regarding rail guns, since so many UNSC ships use MAC's, albeit with a much larger caliber. 

It also might be interesting to take a stab at designing an Earth warship for the stargate universe that, like the Halo ships, is based on a large caliber rail gun that runs almost the length of the whole ship...sort of a ship that is built around the gun, so to speak.  I'm not sure about the math, but if the round is big enough and you get it going fast enough, you might be able to hit a target with enough force that even those Ha'taks that can stand up against multi-megaton nukes could be dealt with in a few hits.
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Offline TNC

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Re: Railguns in Stargate vs. reality
« Reply #4 on: July 04, 2014, 10:12:41 AM »
Well, this is the best look we ever got of the Daedalus' railguns (from ATL: "The Daedalus Variations").  There's not much in the way of a sense of scale, but it is obvious that it is a gatling style weapon with at least six barrels.  I somehow doubt it's 120 mm though.  IIRC, the railguns they brought to Atlantis were said to be the same type as what was installed on the Prometheus.

For the sake of being able to draw the turrets on my BC-305 Excalibur I just assumed they were 30 mm and added a larger 55 mm turret as well.  The larger turret being for anti-Al'kesh fire or firing flak rounds for anti-fighter use.

Regarding the Haloverse's MAC's, from TVTropes (under video games):
Quote
Doing the math from Halopedia, which gets info from the novels, the Orbital Defense Platforms fire 3,000 ton slugs at 60% light speed. This results in a projectile that has 11.62 teratons of kinetic energy. That's 11,620,000,000 kilotons. For reference, the bomb dropped on Hiroshima had an energy yield of 15 kilotons or so, which makes that one slug over 774 million times as strong. For more realization of how ridiculous this number is, take the total energy consumption of the United States in 2005. Each one of these slugs, fired once every five seconds, contains about 467 times that amount.

This seems to have been disregarded, seeing as it came from the notoriously unreliable Halo Encyclopedia. Now it's generally agreed that the Fall of Reach was correct, and that the slugs are fired at 4% the speed of light rather than 60%. Which is still completely ridiculous. The slugs mass 3,000,000 kg, so getting one of them to 4% lightspeed in 5 seconds requires over 7 teranewtons of force. It would've made more sense to make the slugs smaller, as little as a few kilograms, and left the speed at .6c—getting a 10 kg projectile to that speed only takes 360 meganewtons, and yet it hits like a 40 megaton nuke.

So it seems likely you could get something capable of defeating Goa'uld shields (with multiple shots), and would make mincemeat of Hive ships without having to be too absurd.  You'd just have to get it going 105,718 times faster than the regular railguns.
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Offline TNC

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Re: Railguns in Stargate vs. reality
« Reply #5 on: August 07, 2014, 03:38:40 PM »
So here's a quick calculation I did for my fan-fic railgun slugs.  Now we have no idea how big the railguns in Stargate really were or what the slugs were made of, but I figure this could give us a rough idea of what they were capable of... 

First the railgun slugs as per my fan-fic are 30 x 203 mm and are (mostly) made out of tungsten.  Tungsten has a density of 19.25 g/cm3, and the slugs themselves are mostly cylinders with a cone at the tip. Assuming that you can just add the volumes of the cylinder and cone together, we get a volume of 129.35507751155973659369934130653 cm3.  So this means the projectile weighs 2.4900852420975249294287123201507 kg.  (I'm leaving all the extra digits in to insure calculation accuracy).  So the kinetic energy of the projectile at Mach 5 (1701.4665 m/s) is, 3604.3837594600977833366931334018 kJ which we'll just round to 3,604 kJ.  Now I have no idea how to equate 3,504 kJ to anything anyone can commonly relate to...
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Offline The Unbound

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Re: Railguns in Stargate vs. reality
« Reply #6 on: August 27, 2014, 04:45:11 AM »
Well, then I have a handy link for you: Wolfram|Alpha.
Steady on.

Offline TNC

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Re: Railguns in Stargate vs. reality
« Reply #7 on: August 28, 2014, 11:34:09 PM »
Thanks for the link!

There's also this http://en.wikipedia.org/wiki/TNT_equivalent.  According to this Wikipedia entry, a gram of TNT releases 4,184 J (which is an arbitrary standard, actual energy is 4,100-4,602 J).  So using this that 3.604 MJ is equal to the amount of energy released by 861.5 grams of TNT, which basically says the same thing that the site The Unbound linked to (3.6 MJ is ≈ 0.86 x the energy released by 1 kg of TNT) said.
“Battle is not a simulation. It’s blood and screams and funerals.” – Capt. Georgiou – Star Trek: Discovery – “The Vulcan Hello”