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Speed/Time values do not add up

Posted: Sat Jun 18, 2016 8:44 am
by Myrm
Hi

As you all know if you target something you'll get not only the distance to the object but also the time it'll take you to reach that target at your current speed. The faster you go the quicker the timer counts down, and conversely the slower you travel the slower the time ticks by.

However, I have noticed that once you reach a certain speed, then no matter how much faster you travel the timer ticks down at a constant rate.

So does travelling at over, say, 100x the speed of light (I can't remember the exact speed that needs to be reached before the timer settles, but 100x is just representative here) really get you anywhere faster? (with, of course the exception of between systems jumping).

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 9:58 am
by Loriath
Remember, your speed is affected by gravity as well. If you start from the jump in point and head to an object (assume the only object in the system besides the main star, and assume it is another star) you start to accelerate.

Even at 100% throttle, you will continue to accelerate till you are halfway to the destination, then the ship starts to automatically decelerate. This is because the ship drive is being affected by the gravity of the other object. That is why when you use the 75% throttle trick at the seven second mark, it will keep saying 7 seconds as your ship slows.

It's physics. And it may or may not be accurate in game, but it is still physics.

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 11:00 am
by smartroad
Personally I would like a bit more logic to the time given. The ships computer should be able to calculate the time needed as it knows what throttle you have set, what objects are between you and the target and should be able to work out the approximate speed, acceleration and deceleration to get to the target. To be honest the time on the display is next to useless, all it is good for is making sure you set the throttle so the timer doesn't drop below 6-7 seconds to ensure you don't overshoot

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 11:14 am
by Myrm
smartroad wrote:Personally I would like a bit more logic to the time given. The ships computer should be able to calculate the time needed as it knows what throttle you have set, what objects are between you and the target and should be able to work out the approximate speed, acceleration and deceleration to get to the target. To be honest the time on the display is next to useless, all it is good for is making sure you set the throttle so the timer doesn't drop below 6-7 seconds to ensure you don't overshoot


Exactly! :)

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 1:49 pm
by TorTorden
smartroad wrote:Personally I would like a bit more logic to the time given. The ships computer should be able to calculate the time needed as it knows what throttle you have set, what objects are between you and the target and should be able to work out the approximate speed, acceleration and deceleration to get to the target. To be honest the time on the display is next to useless, all it is good for is making sure you set the throttle so the timer doesn't drop below 6-7 seconds to ensure you don't overshoot


But that is EXACTLY what it is doing.
But as has been mentioned your speed is always changing so will your time of arrival.
On top of the changing velocity I also don't know of any pilot that's flying straight at a station.
Certainly not a planet settlement.

The timer was and should never be confused for an actual countdown.
But should be used for what it is:
A function of your velocity and distance.
Anything else will just be infuriating.

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 2:23 pm
by Walter
Reluctantly, I have to disagree with Loriath: I don't believe the gravity wells at each end of your journey are part of the equation, much as they might do in the real universe.

It's an implementation of the formula we learnt at school: d / v = t.

Because the d and v are constantly changing (unless you fix your speed to below the maximum), so is the t. At some of the changing values of d and v, the t can appear to be stable, but it's always the result of the calculation.

The information you are given is just reporting on the remaining journey time at that instant: if you continue travelling at this speed you will reach your target in this time.

Of course, if you do continue at that speed you will smack into your target rather than land gracefully.

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 3:11 pm
by TorTorden
Walter wrote:Reluctantly, I have to disagree with Loriath: I don't believe the gravity wells at each end of your journey are part of the equation, much as they might do in the real universe.

It's an implementation of the formula we learnt at school: d / v = t.

Because the d and v are constantly changing (unless you fix your speed to below the maximum), so is the t. At some of the changing values of d and v, the t can appear to be stable, but it's always the result of the calculation.

The information you are given is just reporting on the remaining journey time at that instant: if you continue travelling at this speed you will reach your target in this time.

Of course, if you do continue at that speed you will smack into your target rather than land gracefully.


You definitely become affected by nearby objects, it just works a bit oddly and rather simplistic.

Closer you are to an object the less efficient your drive gets.

The slow down warning is actually displayed when you are going faster than your proximity to a stellar object would normally allow and your FSD's performance pretty much cuts, can't slow, can't speed up until you are within "parameters" again.

Its also not about physics, but game mechanics (I'm mostly guessing here).
Supercruise in ED cannot be time dilated like space games of old since it's multiplayer. So what they do instead is compress\dilate space (hence why cruise and normal are seperate instances), the further you are from an object the more compressed distances can become, closer you get, the game decompresses so you will still be able to manoeuvre with some precision, and fine enough correlation so you can drop into normal space.

Anyone can test this by simply flying about 800 000 ls - 1 000 000 ls away from a star into the black you can pretty much stop instantly from 1000C to 30km\s in seconds. And speed back up again the same way.


But come crashing at max speed into lhs 3447 and your throttle becomes unresponsive and you scream past.
It's from what I guess that you have broken into one area's compression into another with too much velocity so the game needs to correct it, or something. They could easily increase I suppose the area compression is affected but I think FD decided it's a little more engrossing to have to manually handle the approach, and I believe they are correct, it's adds a little bit of thought and skill to cruise which other wise would just be "point and wait".

The game's FSD is now capped at 2001C , but for example heading to Hutton orbital you only get to about 950C at most.
Head out into the black where you move towards other stellar objects however you can reach top velocity in half the time it takes to reach Hutton.

And as for d/v=t, remember in ED and space in general all the things move, including planets and bases, it's just they move a lot slower than our FTL driven space ships.

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 3:28 pm
by smartroad
TorTorden wrote:But that is EXACTLY what it is doing.
But as has been mentioned your speed is always changing so will your time of arrival.
On top of the changing velocity I also don't know of any pilot that's flying straight at a station.
Certainly not a planet settlement.

The timer was and should never be confused for an actual countdown.
But should be used for what it is:
A function of your velocity and distance.
Anything else will just be infuriating.


But my Satnav software doesn't do that and it has to deal with my velocity and distance changing constantly :D It only changes the time of arrival on anything outside of its estimates happen (I go slower then what it considers the road speed to be for example). If the timer shouldn't be used as a countdown what is the point of having it there then?

The ships computer knows where you are, where you are heading and (in a system with a full scan) what is between you and your destination. If knows the rate the ship can accelerate and decelerate at a given distance from anything en-route and should be able to give a reasonably accurate calculation of how long it would take you to get there at any given throttle setting. If you change direction the sure the time will change but once you face your target again then it should stabilise back to how long it will actually take.

At the moment all it is doing is (as Walter notes) calculating your instantaneous speed against the remaining distance, which is a very simplistic way of calculating the time to target and only works reliably when speed is constant. Seeing as we can't set our ships in SC at a constant speed (as it fluctuates depending on distance to target and any gravity wells around it), the calculation should take that into account.

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 4:27 pm
by Walter
TorTorden wrote:And as for d/v=t, remember in ED and space in general all the things move, including planets and bases, it's just they move a lot slower than our FTL driven space ships.

This is true and I think FD just ignore it. Vega Strike had built-in accommodation for mass and movement - you couldn't fly directly to a distant target but only in a series of curves.

(It's possible that the movement of stellar objects should be taken account of by FD. I'm thinking that the bugs where a SRV/ship spawns inside a planet or star on startup is due to the universe moving on - calculations done server-side - but the vehicle remaining in the location it had when the commander logged off - local records.).

I was wrong to suggest that the gravity wells don't affect the flight. What I should have said was that they only affect the calculations once you are close enough - within the blue rings.
smartroad wrote:If the timer shouldn't be used as a countdown what is the point of having it there then?

Stop asking awkward questions.

Re: Speed/Time values do not add up

Posted: Sat Jun 18, 2016 8:47 pm
by TorTorden
Well, if it was a predictive timer it would be off by at least a few seconds EVERY SINGLE time.
Like google's time to destination is ALWAYS OFF.

Then we would have posts asking "Why is the time to destination always off by x seconds".
Instead we have a technically correct time to destination that consistently updates, it is always correct, it just changes constantly.
So it feels a bit like "microsoft time" in the late 90's, where counters would go 90minutes, then suddenly drop to 3 minutes, slowly increase until 8, and stayed there for 45 minutes when the task windows was doing either bluescreened or finished.

The current timer is actually the usefull one, I consistently use it to maintain throttle consistently on my cruise approach.
If I'm under 8 seconds I keep it at 75%-50%, more than that I throttle up, then down as it hits 10 seconds etc etc.