Supercruise: can we fix this?

[Lacika2000]

Being new to the forum, I am trying to thread lightly...

I am not sure if my experience is unique, but it is repeatable:

After arriving at a star and supercruising to a station will take substantially less time than starting from the station and supercruising to the star. First I thought "it is gravity, stupid!", but the calculations don't seem to hold that view.

Example: Kamadhenu system
The star Kamadhenu is 0.8008 solar mass, which is 1.59279*10^(30) kg. You arrive around 3.70 Ls away from the star. This gives on a Python (let's assume 350 t, so 350,000 kg) approximately 30,241 kN force of pulling.

Having the star behind the ship and facing the closest station (Shajn Market), and hitting full throttle, I can reach 5.0 c speed in around 19 s.

This means that the ship has enough power to overcome the 30+ MN gravitational pull and add continuously to the speed (i.e., accelerate) to reach 5 c in less than 20 seconds.

After arriving at the station, I position the ship so that the planet, Kamadhenu 1, having a 2.1624 Earth mass, so around 1.29139*10^(25) kg, exerting a gravitational pulling force of 149 kN on the Python at 0.15 Ls distance to the planet, is behind the ship, and hit full throttle again. I can accelerate to 5.0 c speed in around 54 s (!!!).

This means that suddenly the same ship does not have enough power to overcome a considerably smaller gravitational pull and cannot accelerate to 5 c in 20 seconds, it needs more than twice that time. Note that the planet's gravitational pull is a mere 0.49% of that of the star at the above mentioned starting distances, but nevertheless the ship struggles to accelerate, it can't even achieve what it could 'easily' when moving away from the star.

Just to be clear, even though I am closer to the planet than the star, the large difference in mass between planet and star results in a much smaller gravitational pull in the case of the planet, but still, I cannot accelerate to 5 c quicker than in the case of the same trip starting from the star. This is even more strange that during the trip from the station to the star, the star is actually pulling the ship with around 2 N force in the beginning of the trip, away from the planet and towards the star.

Furthermore, if gravity was taken into account (and with the traditional way of calculating forces acting on the ship), than moving away from the star from the starting position of 3.7 Ls distance to around 37 Ls would mean that the ship has already overcome around 99% of the total gravitational pull of this star. In other words, its power can be used almost fully (99%) to increasing its speed.

Which is clearly not that case in supercruise, as it will limit the speed increase substantially when reaching the first 10-15% of the distance to be covered, compared to the original acceleration from the star (where you have the highest gravity pull in this system).

Something is clearly broken... maybe my calculations? Did someone made similar tests and calculations in other systems? (preferably single star, so you don't need to take into account multiple heavy celestial objects pulling on the ship...) Please let me know, especially if you have test data (flight time needed to reach 5 c) in other systems. I am willing to do the calculation, if needed.

[EDIT: I have made a mistake on converting the Python mass to kg at first, but now I have updated the calculated values for the gravitational pull forces to the correct ones.]

[EDIT2: if you want to jump to the part debunking the gravity based arguments based on an independent work measuring supercruise max speeds, see this post in the queue.]

 

[Taifu]

I don't know for sure, but I was under the impression that the FSD compresses space and its how close you are to "stuff" or how much "stuff" is near by, that limits your speed. If this is true it, must have an impact on your ability to accelerate.

In other word you are always at the top speed of your FSD (when at 100% throttle), which is limited more by its ability to compress the space around you than Newtonian gravity pulling on it.

For example, when you pass by an asteroid belt, something that is not visible from Super Cruse, you get brief "Overspeed" warnings (or weird slowing or slow acceleration) because there is "stuff" there that your FSD can't compress, before it returns to normal after you have blasted past it.

 

[varonica]

Being new to the forum, I am trying to thread lightly...

I am not sure if my experience is unique, but it is repeatable:

After arriving at a star and supercruising to a station will take substantially less time than starting from the station and supercruising to the star. First I thought "it is gravity, stupid!", but the calculations don't seem to hold that view.

Yes it's gravity, but not as you know it. It's not broken, you just don't understand how it works. The max Supercruise speed is limited by the strength of the local gravitational field, so it will always take longer to fly towards a large object with high gravity than it takes to fly away, because when you are flying away the local gravitational field is decreasing and the ship is going faster and faster, when you fly towards an object with a large gravitational field the field is increasing as you approach so you fly slower and slower. This is also affected by any nearby bodies, avoiding these while traveling through star systems will substantially decrease in-system travel time.

There's also the assist effect to take into account that is used to stop players flashing past an object they are traveling to, if you have targeted an object the assist will kick in by slowing you down as you approach regardless of the local gravity and effects. So if you are testing you need to avoid actually targeting the object you are flying towards.

In your case you are flying from the star, a large gravity field, towards a station in orbit around a planet, a small gravity field. So when flying towards the station you are leaving a large gravity field that slow you down substantially and entering a smaller gravity field that won't slow you down as much. When you do the reverse you are leaving a much smaller gravity field and pick up speed a lot faster as you exit its area of effect. Unfortunately unlike the real universe gravity isn't univeral in game so you quickly leave the area of effect of a small body but not of a large body like a star. In the real universe the gravity of a body extends to infinity, but not in the ED universe because that would be to difficult to model with 400b stars and trillions of planets. Also keep in mind that the slowdown isn't always as fast, you will often see a message that says "slowdown", which means you are encountering a braking effect as you entering an area of higher gravity than your current speed allows for and being slowed down.

It's complicated but it has been tested by a lot of people and I assure you it isn't broken, it's how gravity effects a ship in the imaginary physics of Supercruise, it's a global game variable that is consistent throughout the galaxy.

So you can't calculate the effect as if it's the actual universe, it's a semi-accurate model but limitations of the modeling mean that there will always be an error factor, and in Supercruise we aren't in normal space so you can't use the same formulae that apply to gravity in the real universe, they simply don't work for Supercruise physics.

 

[Lacika2000]

Yes it's gravity, but not as you know it. It's not broken, you just don't understand how it works. The max Supercruise speed is limited by the strength of the local gravitational field, so it will always take longer to fly towards a large object with high gravity than it takes to fly away, because when you are flying away the local gravitational field is decreasing and the ship is going faster and faster, when you fly towards an object with a large gravitational field the field is increasing as you approach so you fly slower and slower. This is also affected by any nearby bodies, avoiding these while traveling through star systems will substantially decrease in-system travel time.

...

In your case you are flying from the star, a large gravity field, towards a station in orbit around a planet, a small gravity field. So when flying towards the station you are leaving a large gravity field that slow you down substantially and entering a smaller gravity field that won't slow you down as much. When you do the reverse you are leaving a much smaller gravity field and pick up speed a lot faster as you exit its area of effect. Unfortunately unlike the real universe gravity isn't univeral in game so you quickly leave the area of effect of a small body but not of a large body like a star. In the real universe the gravity of a body extends to infinity, but not in the ED universe because that would be to difficult to model with 400b stars and trillions of planets. Also keep in mind that the slowdown isn't always as fast, you will often see a message that says "slowdown", which means you are encountering a braking effect as you entering an area of higher gravity than your current speed allows for and being slowed down.

It's complicated but it has been tested by a lot of people and I assure you it isn't broken, it's how gravity effects a ship in the imaginary physics of Supercruise, it's a global game variable that is consistent throughout the galaxy.

So you can't calculate the effect as if it's the actual universe, it's a semi-accurate model but limitations of the modeling mean that there will always be an error factor, and in Supercruise we aren't in normal space so you can't use the same formulae that apply to gravity in the real universe, they simply don't work for Supercruise physics.

Perhaps it was not clear from my post, so my apologies for that, but the problem I have is that it is faster to travel from the star to the station or planet (from high gravity to low gravity) than from the station/planet to the star (from low gravity to high gravity).

This is the reason I have actually calculated the gravitational forces at the point of departure taking into account the masses and distances. The gravitational force is around two-three orders of magnitude (so 100-1000 times) higher at the star than at the station/planet. But I can still accelerate faster when leaving the star than when leaving the station/planet. Please see the example again for the details of the calculations (mass, distance, force).

I can reproduce this phenomenon in many systems, it is all the same: starting from the star it is always faster to travel to a station/planet than starting from a station/planet traveling to the star. This is the exact opposite what you would expect based on a gravitational field effect based on the masses indicated in the star map.

How is this then 'gravity' related? And if it is not, why do you claim to be related to gravity in the first place? I found it somewhat pretentious, if you don't mind me saying, that according to you I don't understand gravity, while I have actually calculated the gravitational forces in place based on the experimental data and you have not rebutted these calculation in any meaningful way (or seem to understand my post, to be honest)...

Curious to hear others' views and experiences in supercruise travel times.

If you see a blatant error in my data/calculations, please let me know. If you think there is an error in the approach, I am happy to dive into the details.

 

[klusik]

It's a gravity field. Meaning it's numerical interpretation, imagine a 2D square network where all the joints have value. The plane of that network is the plane between you and other objects. Every joint has a number depending of the gravity potential in given joint. Now imagine all this in 3D and that's it, as I got it :-D

 

[Lacika2000]

I don't know for sure, but I was under the impression that the FSD compresses space and its how close you are to "stuff" or how much "stuff" is near by, that limits your speed. If this is true it, must have an impact on your ability to accelerate.

In other word you are always at the top speed of your FSD (when at 100% throttle), which is limited more by its ability to compress the space around you than Newtonian gravity pulling on it.

For example, when you pass by an asteroid belt, something that is not visible from Super Cruse, you get brief "Overspeed" warnings (or weird slowing or slow acceleration) because there is "stuff" there that your FSD can't compress, before it returns to normal after you have blasted past it.

A uniform compression of distances in invariant in a gravitational field, so it will increase the forces, but not change their relative amounts: it is still the star that will dominate the gravitational pull of the system anywhere but a few Ls away from the planets. So when you managed to get 'away' from a planet more than 1-3 Ls, you should feel the star's pull more than the planet's pull across the whole system. This way the travel time from the planet to the star should be faster than the other way around, as we should be accelerating 100-1000 times faster away from a planet than from a star.

But this is clearly not the case in any of the systems I have travelled to so far in Elite Dangerous...

 

[Lacika2000]

It's a gravity field. Meaning it's numerical interpretation, imagine a 2D square network where all the joints have value. The plane of that network is the plane between you and other objects. Every joint has a number depending of the gravity potential in given joint. Now imagine all this in 3D and that's it, as I got it :-D

Exactly these values I have calculated in my post. The pull at the star is more than 1000 times higher than at the station/planet. But you still can accelerate faster at the star than at the planet. So the gravity theory opposes the actual in-game experience...

 

[Xenogenics]

still waiting for the day intra system supercruise warps are a thing

 

[klusik]

Exactly these values I have calculated in my post. The pull at the star is more than 1000 times higher than at the station/planet. But you still can accelerate faster at the star than at the planet. So the gravity theory opposes the actual in-game experience...

I see, I am thinking about it as a "hysteresis," I mean you surely noticed, you can go to the planet faster than from the planet. Because you went to fast, it's just faster, but you might be taken of supercruise, if exceeds some limit.

 

[Ameeleean]

There are lot of things that make no sense at all if You look at ED as a space sim but are made for the game to be playable. Supercruise is one of them. Personally I would prefer entry point to be away from star as it is the most violent and dangerous object in typical star system but again ED is a game and needs single entry point for all players so those who like to do piracy, PvP (ganks included) have a chance to find they prey in single spot - all those trigger happy players are happy that we have that and supercruise assist which goes in straight line - making interception easy and possible. Personally I think ED focuses too much on combat (just look at Odyssey) but apparently majority of our fellow ED player base like combat as their prime activity in game - which explains why game development is greatest in this area imho.

 

[klusik]

There are lot of things that make no sense at all if You look at ED as a space sim but are made for the game to be playable. Supercruise is one of them. Personally I would prefer entry point to be away from star as it is the most violent and dangerous object in typical star system but again ED is a game and needs single entry point for all players so those who like to do piracy, PvP (ganks included) have a chance to find they prey in single spot - all those trigger happy players are happy that we have that and supercruise assist which goes in straight line - making interception easy and possible. Personally I think ED focuses too much on combat (just look at Odyssey) but apparently majority of our fellow ED player base like combat as their prime activity in game - which explains why game development is greatest in this area imho.

Possibly. I don't really know, but it seems like that.

 

[varonica]

Exactly these values I have calculated in my post. The pull at the star is more than 1000 times higher than at the station/planet. But you still can accelerate faster at the star than at the planet. So the gravity theory opposes the actual in-game experience...

No I've explained this, that only works if you assume the gravity fields extend to infinity while tapering at the expected rate, and they don't in the game, they suddenly cut off and the planets one cuts off much closer than to it's surface than the star. Also you use the incorrect description, you aren't "accelerating" at the star, you can't "accelerate" at the star, you can only slow down when flying towards the star, it only appears to accelerate because as I said the area of effect of the planet gravity cuts off suddenly while still quite strong instead of tapering off gradually.

What happens is you are constrained in your speed by the gravity of the planet, for the first part of your travel towards the star your maximum speed is determined by the gravity of the planet behind you, but that abruptly stops and you suddenly drop into the area of effect of the star, and the gravity field of the star at that point is much lower than the one you just left, so you "appear" to "accelerate" towards the star, but that's only your FSD drive increasing speed to the maximum allowed by the stars gravity in the location you are in. Once you reach that maximum speed you stop moving faster and start slowing down as you travel towards the star.

The effect you are experiencing is an artifact of the limitation of the gravity model of the simulated galaxy and nothing else, try to apply any sort of math to it assuming that gravity of any given body extends to infinity and you quickly run in to the limitations of the model.

 

[Bottom Hat]

I thought it was just space magic

 

[Taifu]

I thought it was just space magic

That and a healthy disregard for Newtonian physics for the benefit of gameplay.

 

[Taifu]

A uniform compression of distances in invariant in a gravitational field, so it will increase the forces, but not change their relative amounts: it is still the star that will dominate the gravitational pull of the system anywhere but a few Ls away from the planets. So when you managed to get 'away' from a planet more than 1-3 Ls, you should feel the star's pull more than the planet's pull across the whole system. This way the travel time from the planet to the star should be faster than the other way around, as we should be accelerating 100-1000 times faster away from a planet than from a star.

But this is clearly not the case in any of the systems I have travelled to so far in Elite Dangerous...

I don't disagree with anything you have said with regard to the workings of gravity, so if its clearly not the case, it logically follows that Super Cruse must be using something else.

So...

If the maximum speed of your FSD is based on its ability to compress the space around it, and if matter inside its sphere of influence limits its ability to compress space, it follows that it is the distance from matter that is the limiting factor and not how large the gravitational force from the matter is.

In your example from the OP, 3.70 Ls is a lot further away than 0.15 Ls from uncompressible matter, and your speed is higher, sooner, and you accelerate faster because you are further away because the maximum speed is higher further away.

Now don't start applying any more logic to it than distance from object. The size of the object has no influence as demonstrated by asteroid belts and even space stations. And when you factor in FDev's proclivity for taking the easiest option that produces a close enough result, distance from object is the obvious metric of most importance.

Distance from object annnnd space magic of course. In fact space magic might be slightly more important.

 

[NyanTurian]

If these are the best explanations for how or why Supercruise works the way it does, it is really only a matter of personal preference and nothing to do with physics sadly.

 

[Lacika2000]

No I've explained this, that only works if you assume the gravity fields extend to infinity while tapering at the expected rate, and they don't in the game, they suddenly cut off and the planets one cuts off much closer than to it's surface than the star. Also you use the incorrect description, you aren't "accelerating" at the star, you can't "accelerate" at the star, you can only slow down when flying towards the star, it only appears to accelerate because as I said the area of effect of the planet gravity cuts off suddenly while still quite strong instead of tapering off gradually.

What happens is you are constrained in your speed by the gravity of the planet, for the first part of your travel towards the star your maximum speed is determined by the gravity of the planet behind you, but that abruptly stops and you suddenly drop into the area of effect of the star, and the gravity field of the star at that point is much lower than the one you just left, so you "appear" to "accelerate" towards the star, but that's only your FSD drive increasing speed to the maximum allowed by the stars gravity in the location you are in. Once you reach that maximum speed you stop moving faster and start slowing down as you travel towards the star.

The effect you are experiencing is an artifact of the limitation of the gravity model of the simulated galaxy and nothing else, try to apply any sort of math to it assuming that gravity of any given body extends to infinity and you quickly run in to the limitations of the model.

I will take again a cautious approach and assume I did not explain myself properly. So let me try again:

When we are in supercruise with zero throttle, we cruise with a steady speed of 30 km/s. A steady speed means that the forces acting on the ship are all cancelled out, so the forward pushing force of the ship is cancelling out any gravitational pull from the surrounding. If either the ship's own propulsion (throttle higher than zero) or the gravitational pull would be 'out of this perfect balance', the ship would increase its speed and move in the direction of force acting upon the ship: if the gravitational pull is stronger, the ship would start to gain speed (i.e., accelerate) towards the star, if it's own propulsion is stronger, it would gain speed (i.e., accelerate) in the direction the ship is pointed at.

Having a steady (minimum supercruise) speed of 30 km/s at zero ship throttle, with the star behind the ship and the ship pointing to the direction of the target station, the ship does not accelerate. But when I hit full throttle, the ship accelerates (gains speed) as quickly as it is allowed by the game engine possible: I can reach 5.0 c speed in 19 s in the system of Kamadhenu when traveling from the star to the nearest station.

Now this means that the ship has enough thrust (power) in its engines that it can overcome the gravitational pull of the star: 30,241 kN force exerted on the ship at 3.7 Ls distance from the star.

The gravitational force is decreasing with increasing distance (there is an inverse quadratic relationship between the force and the distance). This means that the force exerted by the star with decrease fairly quickly when moving away from the star: the force is reduced by 90% at 12 Ls distance from the star.

This also means that if the ship could overcome the gravity pull at 3.7 Ls distance, it will be more than capable to overcome the lower gravitational pull at higher than 3.7 Ls distances from the star. Since around the star we have the highest gravitational pull in the system (this is the reason that the star is in the center in a single star system), there is not other location in the system where the ship's propulsion can be 'challenged' more than here.

If the forces acting on the ship have a net positive amount (propulsion forward vs gravitational pull backward), the ship will accelerate. INDEFINITELY, if the force keep existing (i.e., we don't run out of fuel). There is no maximum speed at a given gravitational field, because A) we don't use relativistic speed restrictions, B) there is no other way the ship can lose energy: there is now 'air resistance' in space, there is no friction, etc. In other words, if the ship is capable overcoming the force holding it back, it will gain speed as long as it overcomes this pulling force.

This is simple physics (F=m*a), which is true in classical and relativistic conditions.

So it makes no sense at all in the physical domain that a ship working against the much weaker gravitational force of a planet could only gain speed (accelerate) at a much slower rate when leaving the planet, compared to how quickly it can gain speed when leaving the star, where the gravity pull is the strongest in the system.

This is how gravity works. Btw: there is no cut-off to the gravitational pull. It will become infinitesimally small at large distances, so it can be practically ignored, but not within a star system with planets. If it could be ignored within a star system, there would be no force keeping the planets in their orbit.

Now it is also clear that this is NOT how the supercruise implementation of Elite Dangerous works. So please don't tell me that "it is gravity" and that "you don't understand gravity". Supercruise appears to have very little to do with gravity...

 

[CMDR Von Abrahart]

Its future fisiks - the fact that its called a frameshfit drive means that you are in a different frame of reference that prevents time dilation - otherwise all your clocks would be messed up. I think gravity wells affect the affect of relativity - tbh i dunno. I think its probably to slow you down so it can draw worlds better. Bottom line is its made up stuff - but i like the idea that you move into a different shifted frame of reference - clearly something all future n sh*t.

 

[Lacika2000]

Its future fisiks - the fact that its called a frameshfit drive means that you are in a different frame of reference that prevents time dilation - otherwise all your clocks would be messed up. I think gravity wells affect the affect of relativity - tbh i dunno. I think its probably to slow you down so it can draw worlds better. Bottom line is its made up stuff - but i like the idea that you move into a different shifted frame of reference - clearly something all future n sh*t.

Well, if we were told "this is our own creation to make sure you can be interdicted by pirates or other players, so it is part of the game design, by the way it has nothing to do with physics and it is in fact so counter-intuitive that it is disturbingly illogical to those with a minimal sense of natural sciences, so deal with it or don't play the game", I could accept the explanation.

I just don't like when it is 'blamed on gravity' (or it is suggested that I don't understand basic physics) while supercruise seems to have nothing to do with gravity.

 

[danubezoe]

OP: I understand your thinking, you explain it well and I appreciate your wording and approach to the problem.
I'm sorry but there is a but.
Supercruise is compressing time which is harder to do in a gravity well - Fighting to get out of a suns well is harder than a planet and their "border" might be set differently (exclusion Zone) so they would rarely be comparable.

Varonica explains it better than me but there it is.

Cheers
DZ