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Pent'noir
Algintal Core
Gallente Federation
70
   |
Posted - 2013.03.16 05:17:00 -
[1] - Quote
This is a fun subject 
I think I'll try and do some math with you, but give me a break if I mess anything up. It's been a long long time since I've done physics. I will just do my work on in this post and you can see everything I'm doing.
Now I already know that you are right that 80Gj is far too much for what we are seeing, but I think I can fit the formulas to match it.
Lets start off with some assumptions. Let's say the projectile velocity is 3000 m/s, which according to wiki is within the limits of current military railguns. (I know... wiki sucks for numbers).
I have no clue how long the turret is, but lets just say it's 5 meters for simplicity.
v = v0 + at, let v0 = 0 m/s
v=at=3000
Vavg = (v0 + v)/2 =v/2 = 3000/2 = 1500 m/s
t=delta x/Vavg = 5/1500 = 0.0034 s
a=v/t =3000/0.0034 =882000 m/ss
Lets assume with a wild guess that the projectile is 5kg
a=F/m or F=am=882000*5kg=4,410,000 = 4.41MN
A newton is a measurement of force, while a joule is a measurement of work which is force through a distance. Our distance is 5m
80Gj=F*5, F=j/delta x= 80Gj/5m=16GN....... wow thats alot, lets fiddle with the projectile mass
F=am
F=work/delta x
F=F
am=work/x
m=work/(a*x)=80Gj/(882000*5)=18140kg
put back into the previous equations.
F=am=882000 m/ss * 18140 kg=15.999GN
F=j/delta x =80Gj/5m=16GN
There we go, thats much better. ignoring the rounding errors, lets just call it 16GN.
Now since I'm just doing math... I didn't see the funniest thing about this until I calculated it. I'm still laughing as i'm typing this.
18140kg is about equal to 40000 pounds or 20 tons... OMG!!!
A 20 ton projectile flying at 3000 m/s.
The in game visuals do not do justice to the horror show that would be a dropsuit being hit with that, or even a tank.
Then there's the thing that was brought up, the projectile is not traveling that fast. Well that would mean the projectile is even heavier. |
Pent'noir
Algintal Core
Gallente Federation
73
|
Posted - 2013.03.17 01:02:00 -
[2] - Quote
This was fun for me, so I'll give it another wack.
I think found a way to make the 80Gj fit. Lets say this isn't the work done on the projectile, but the energy consumed per second of operation, or in otherwords power.
Using a formula found at http://home.insightbb.com/~jmengel4/rail/rail-intro.html
no idea if it is correct, but lets work with it and see what we get.
v(muz)=I(2DLu/m)^.5
v(muz)=Muzzle velocity (Meters/Second)
D=Length of rails (Meters)
m=Mass of projectile (Kilograms)
I=Current through projectile (Amperes)
L=Width between rails (Meters)
u=1.26x10^-6 (The magnetic permeability of free space, Henries/Meter)
Lets assume vmuz=4000m/s
Going on what I remember what the turrets look like,
D=6m
L=0.25m
and lets say mass m=2kg
The only thing left unknown is the current. Solving for that I find
I=2.90 Mamps
This is almost the same problem thats given on the website, but the writer says it actually takes 6.5Ma to do this because of friction and air drag. Thats about 2.24 times the calculated result. Eventhough I know this will be higher for greater Vmuz, I'm going to cheat a little bit and just use that for other calculations. I think it will be within the ballpark.
Just for fun, I'll make up some numbers for the other weapons that I think could fit.
So now lets use some numbers that our forge gun could be using.
Vmuz=7000m/s
D=1m
L=0.1m
m=2kg
Solving, I=11.27Ma..........2.24x11.27Ma=25.2Ma
The sniper rifle
Vmus=2500m/s
D=1.5m
L=0.05m
m=0.5kg
Solving I=4.06Ma............2.24x4.06Ma=9.1Ma
The Large RailGun
VMus=7000m/s
D=6m
L=0.25
m=10kg
Solving I=11.39Ma.........2.24x11.39Ma=25.29Ma
We know the power consumption from
P=E/t =80Gj/1s=80Gw Doc Brown would be proud, to bad its not 1.21Gw
and
P=V*I
V=P/I=80Gw/25.29Ma=3.16kv
So we get a railgun at 25.29Ma and 3.16kv from 80Gw or 80Gj
That doesn't sound that bad, although, now for the bad part.
kinetic energy=0.5*m*v^2
Turret: KE=0.5*10kg*(7000m/s)^2=245Mj
Forge Gun: KE=0.5*2kg*(7000m/s)^2=49Mj
This would mean the turret should be doing 5 times the damage of the forge gun, however, it seems like they are doing the same damage, so they must be using the same projectile mass, which doesn't make much since because why not just have a forge gun on a stand instead of a huge turret.
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Pent'noir
Algintal Core
Gallente Federation
74
|
Posted - 2013.03.17 09:49:00 -
[3] - Quote
Opps, I didn't realize that the railguns are actually Coil Guns.
http://wiki.eveonline.com/en/wiki/Hybrid_Turrets
It says what they are at the bottom under Technology.
Well that would invalidate my second post with calculating the power used by the entire system. Why not just call them Coil Guns. The principles are completely different. There are no rails, just a bunch of coils in a line, thus coil gun. However, I guess the kinetic energy formulas still stand because it is shooting a projectile, it does have mass, and velocity.
Looking at it that the 80Gj refers to the work done on the projectile and not the energy used by the system. The projectiles must have huge amounts of mass or ridiculous velocity.
Or I guess there is always the other option. Their coil guns suck at timing and much of the work done on the projectile is invalidated by opposing magnetic forces. Like an iron bullet stuck between two magnets. Or atleast thats how I see it. I've never built one, but come on, I think i've seen ppl on youtube build them for highschool science projects. |
Pent'noir
Algintal Core
Gallente Federation
74
|
Posted - 2013.03.18 01:11:00 -
[4] - Quote
I wonder what the reason for that could be. When someone says Joule as an electrical power input, it can be a bit confusing. Atleast it is confusing to me. However, it may make more sense to a physicist than an electrical engineer. Maybe it makes the math easier to just leave everything in joules rather than converting it to watts. If I saw that, then the first thing that would pop in my head would be to just divide it by 1s to get watts because that's what my school class taught me, but ofcourse, the time could be anything 0.3s, 5s, 1ps... Interesting, I'll have to look up why they do that. |
Pent'noir
Algintal Core
Gallente Federation
74
|
Posted - 2013.03.18 03:11:00 -
[5] - Quote
Dr Debo Galaxy wrote:I just think this is were people are drawing the line on physics. Not the drop uplinks creating mini wormholes. Not the inertia dampener. Not the any number of other things that don't really make sense science wise. This a rail gun is the point were people are saying "no, this just doesn't make sense".
Yeah, because we actually have rail/coil/gauss guns and they are a cool weapon for the sci-fi fans. Although, i'd say not very practical because of the power requirements and size. But maybe in in the future, so its fun to bs about them on sci-fi games. The other things are far to complicated to bs about and just leave it as a sci-fi mystery that could exist in the distant future until someone proves that they can't. I love reading about wormholes, but don't know nearly enough about it to talk about them... Besides what I have heard many times over. It could take the power production of every sun in the universe to make one. Something about negative energy, beats me, I have no clue. |
Pent'noir
Algintal Core
Gallente Federation
74
|
Posted - 2013.03.18 05:29:00 -
[6] - Quote
The op point is valid if the numbers are muzzle ke because a shot from that would kill anything in one shot when compared to the other weapons we have. Plus the visuals and sounds would be a gross understatement. Although, since nothing is said about it in the description, i'll just assume its the energy stored in the capacitor banks.
Yeah, your right, it's right at the limits of being something no one cares about and something being something ppl can bs or complain about. It's just bs'ing with numbers instead of words.
It will be a fun time if we ever get the full range of eve ammo types. Then i'd say, sure leave the railgun at 80Gj muzzle because there are things like anti-matter bullets also coming your way and the difference between dmg wont seem that great and i'll just think we must have awesome shields and armor. But i'd be crusading for visuals to match what imagine. |
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