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Droidster
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Posted - 2004.07.18 19:21:00 -
[1]
I was trying to apply physics to ship velocity attributes (bad idea?) and the equations do not seem to add up. For example,
ship velocity 130 m/s
ship mass 12M kg
10 MN MWD with thrust = 10M newtons
When MWD is activated the acceleration will be 10/12 = 0.83 m/s2. To travel a given distance the equation should be (?):
time = (SQR(velocity^2 + 2*distance*acceleration) - veclocity) / acceleration
Now assuming you are doing a gate approach (15000 meters), the time to make the approach according to this formula is:
time to approach (seconds) =
(SQR(130^2 + 2*15000*0.83) - 130)/0.83 = 89 seconds
But this is way longer than it takes to this approach in EVE (about 10 seconds).
What is wrong?
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I am motivated by various things, mostly ISK. |
Droidster
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Posted - 2004.07.18 19:21:00 -
[2]
I was trying to apply physics to ship velocity attributes (bad idea?) and the equations do not seem to add up. For example,
ship velocity 130 m/s
ship mass 12M kg
10 MN MWD with thrust = 10M newtons
When MWD is activated the acceleration will be 10/12 = 0.83 m/s2. To travel a given distance the equation should be (?):
time = (SQR(velocity^2 + 2*distance*acceleration) - veclocity) / acceleration
Now assuming you are doing a gate approach (15000 meters), the time to make the approach according to this formula is:
time to approach (seconds) =
(SQR(130^2 + 2*15000*0.83) - 130)/0.83 = 89 seconds
But this is way longer than it takes to this approach in EVE (about 10 seconds).
What is wrong?
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I am motivated by various things, mostly ISK. |
reaTh
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Posted - 2004.07.18 19:36:00 -
[3]
FREAK!!!! get a life man 
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reaTh
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Posted - 2004.07.18 19:36:00 -
[4]
FREAK!!!! get a life man
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phaux
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Posted - 2004.07.18 20:10:00 -
[5]
cant comment on the equations (way too lazy to add up numbers in middle of my summer vacation), but keep looking man, its ppl like you that keep this game in check, hope some1 can comment and help ya out
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phaux
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Posted - 2004.07.18 20:10:00 -
[6]
cant comment on the equations (way too lazy to add up numbers in middle of my summer vacation), but keep looking man, its ppl like you that keep this game in check, hope some1 can comment and help ya out
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SkrittaK
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Posted - 2004.07.18 21:10:00 -
[7]
Edited by: SkrittaK on 18/07/2004 21:13:13
I completely suck at the A2 physics ive been doing this year but i think the maths is a bit more complicated than that mate.
The unit for acceleration is m/s^-2 - so an object that is accelerating at 1 m/s2 will increase its instantaneous velocity by 1m/s every second. It's very difficult to see as you ahvent laid your maths out very well, if you do that its a lot easier to take a look at it. Have you taken the lack of any kind of friction acting on the ship into account?
If the maths has been fiddled then its probably in a gameplay aspect so it doesnt take too long to travel, so ive not got too many qualms with that.
Semper Fidelis
Legion boys, we are here, shag your women and drink your beer! :) |
SkrittaK
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Posted - 2004.07.18 21:10:00 -
[8]
Edited by: SkrittaK on 18/07/2004 21:13:13
I completely suck at the A2 physics ive been doing this year but i think the maths is a bit more complicated than that mate.
The unit for acceleration is m/s^-2 - so an object that is accelerating at 1 m/s2 will increase its instantaneous velocity by 1m/s every second. It's very difficult to see as you ahvent laid your maths out very well, if you do that its a lot easier to take a look at it. Have you taken the lack of any kind of friction acting on the ship into account?
If the maths has been fiddled then its probably in a gameplay aspect so it doesnt take too long to travel, so ive not got too many qualms with that.
Semper Fidelis
Legion boys, we are here, shag your women and drink your beer! :) |
dcell
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Posted - 2004.07.19 00:55:00 -
[9]
Assuming Constant Acceleration, which I assume is implied while the MWD is running, the equation of motion would be
(1/2)*a*t^2 + Vo*t = distance to travel
In the case of your ship a = F/m = .83m/sec^2 and Vo = 130m/sec
You get 89.7 seconds to travel a distance of 15000 meters with the MWD continuously running.
This means you are correct Droidster, but Physics doesn't apply in this game as far as propulsion. Just look at the fact that your ship reaches a velocity cap in deep space. Technically, if the engines were running the entire time, your speed should continue to go up (at least until you begin approaching the speed of light), but it doesn't. In space, making the assumption of negligible external forces acting on the ship, to say you have a max speed << c is kinda rediculous, unless the engines just shutoff once the desired speed has been reached.
Look at the velocity you should be travelling by the time you reach the gate:
Taking V = dx/dt you get V(t) = at + Vo.
V(89 seconds) = 204 m/sec. The MWDs and Afterburners jump the number much faster than it should, so I guess applying Physics is not the right idea.
But then again, I am just an undergrad Physics student lol.
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dcell
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Posted - 2004.07.19 00:55:00 -
[10]
Assuming Constant Acceleration, which I assume is implied while the MWD is running, the equation of motion would be
(1/2)*a*t^2 + Vo*t = distance to travel
In the case of your ship a = F/m = .83m/sec^2 and Vo = 130m/sec
You get 89.7 seconds to travel a distance of 15000 meters with the MWD continuously running.
This means you are correct Droidster, but Physics doesn't apply in this game as far as propulsion. Just look at the fact that your ship reaches a velocity cap in deep space. Technically, if the engines were running the entire time, your speed should continue to go up (at least until you begin approaching the speed of light), but it doesn't. In space, making the assumption of negligible external forces acting on the ship, to say you have a max speed << c is kinda rediculous, unless the engines just shutoff once the desired speed has been reached.
Look at the velocity you should be travelling by the time you reach the gate:
Taking V = dx/dt you get V(t) = at + Vo.
V(89 seconds) = 204 m/sec. The MWDs and Afterburners jump the number much faster than it should, so I guess applying Physics is not the right idea.
But then again, I am just an undergrad Physics student lol.
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DeFood
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Posted - 2004.07.19 08:42:00 -
[11]
EVE, like most (usually multiplayer) spacegames with a velocity cap is actually a submarine simulator.
The simplest way to model a submarine simulator correctly is to add a drag force that opposes accelleration and is a function of velocity :-
So, given df the "drag factor" of an object - this is a constant that represents essentially how streamlined an object is in the fluid. Smaller numbers mean more streamlined. Given df we can compute D - the drag force
D = df * vŠ
To compute how the object is accellerating then, you take the Thrust (T) and subtract the Drag (D) to arrive at the nett force (F)
F = T - D
Then, that goes into your standard accelleration equation: F = m * a
Meaning, you can calculate accelleration in a submarine simulator by solving the accelleration equation for a, and substituting in the drag formula :-
a = (T - df * vŠ) / m
Now, if we knew what the engine thrust was, we could solve that to find out the drag factor. And probably arrive at numbers that are entirely wrong.
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DeFood
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Posted - 2004.07.19 08:42:00 -
[12]
EVE, like most (usually multiplayer) spacegames with a velocity cap is actually a submarine simulator.
The simplest way to model a submarine simulator correctly is to add a drag force that opposes accelleration and is a function of velocity :-
So, given df the "drag factor" of an object - this is a constant that represents essentially how streamlined an object is in the fluid. Smaller numbers mean more streamlined. Given df we can compute D - the drag force
D = df * vŠ
To compute how the object is accellerating then, you take the Thrust (T) and subtract the Drag (D) to arrive at the nett force (F)
F = T - D
Then, that goes into your standard accelleration equation: F = m * a
Meaning, you can calculate accelleration in a submarine simulator by solving the accelleration equation for a, and substituting in the drag formula :-
a = (T - df * vŠ) / m
Now, if we knew what the engine thrust was, we could solve that to find out the drag factor. And probably arrive at numbers that are entirely wrong.
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Teutobod
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Posted - 2004.07.19 11:06:00 -
[13]
Now my head hurts
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Teutobod
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Posted - 2004.07.19 11:06:00 -
[14]
Now my head hurts
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Del Narveux
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Posted - 2004.07.19 11:13:00 -
[15]
To some extent the drag actually makes sense, since space isnt really a pure vacuum...thers gases, mini-meteors and dust particles floating around, especially near planets.
Also makes obvious sense from a gameplay perspective, a true-to-form space thrusting situation would be pretty nasty...
_________________
[SAK] And Proud Of It!
aka Cpt Bogus
Is that my torped sig cloaking your base? |
Del Narveux
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Posted - 2004.07.19 11:13:00 -
[16]
To some extent the drag actually makes sense, since space isnt really a pure vacuum...thers gases, mini-meteors and dust particles floating around, especially near planets.
Also makes obvious sense from a gameplay perspective, a true-to-form space thrusting situation would be pretty nasty...
_________________
[SAK] And Proud Of It!
aka Cpt Bogus
Is that my torped sig cloaking your base? |
Shamis Orzoz
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Posted - 2004.07.19 11:13:00 -
[17]
Afterburners and MWD's do not follow any of the laws of physics. If they did your ship would keep accelerating as long as you had them turned on. So don't bother trying to figure out anything based on real physics. It's a game.
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Shamis Orzoz
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Posted - 2004.07.19 11:13:00 -
[18]
Afterburners and MWD's do not follow any of the laws of physics. If they did your ship would keep accelerating as long as you had them turned on. So don't bother trying to figure out anything based on real physics. It's a game.
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King Kill33
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Posted - 2004.07.19 11:27:00 -
[19]
 Originally by: Del Narveux
To some extent the drag actually makes sense, since space isnt really a pure vacuum...thers gases, mini-meteors and dust particles floating around, especially near planets.
Also makes obvious sense from a gameplay perspective, a true-to-form space thrusting situation would be pretty nasty...
Yes, but there is not enough matter in space to actually provide a drag worth considering from the physics standpoint. It's negligible. The closest thing to drag would be flying into the solar wind, which force can be envisioned by trying to push a raging bull away with your fingertip.
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King Kill33
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Posted - 2004.07.19 11:27:00 -
[20]
Originally by: Del Narveux
To some extent the drag actually makes sense, since space isnt really a pure vacuum...thers gases, mini-meteors and dust particles floating around, especially near planets.
Also makes obvious sense from a gameplay perspective, a true-to-form space thrusting situation would be pretty nasty...
Yes, but there is not enough matter in space to actually provide a drag worth considering from the physics standpoint. It's negligible. The closest thing to drag would be flying into the solar wind, which force can be envisioned by trying to push a raging bull away with your fingertip.
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Zopha
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Posted - 2004.07.19 11:32:00 -
[21]
Originally by: Del Narveux
Also makes obvious sense from a gameplay perspective, a true-to-form space thrusting situation would be pretty nasty...
Elite:Frontier has that and I hated it. Combat was nearly impossiable against a small ship at speed. Trying to figure out what way to point and trust so you could go another way, ug. I used to turn on the autopoilt and speed up time in the hopes I'd ram them out of existance.
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Zopha
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Posted - 2004.07.19 11:32:00 -
[22]
Originally by: Del Narveux
Also makes obvious sense from a gameplay perspective, a true-to-form space thrusting situation would be pretty nasty...
Elite:Frontier has that and I hated it. Combat was nearly impossiable against a small ship at speed. Trying to figure out what way to point and trust so you could go another way, ug. I used to turn on the autopoilt and speed up time in the hopes I'd ram them out of existance.
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