ETA Computation Option Before Launch to 'in system' Destinations.

[Baobobafet]

This could be also be a desireable option for in system travel. (knowing this is already being used to give ETA's for stellar journey's.) Stocking your ship with equipment fuel ect. and then being able to determine ETA similarly would give a pilot the optimal trip time (computing any weight variables into the mix) for an efficient trip 'in system'. This could be useful in planing a journey using the system map to determine the most favourable launch window and whether a layover is advantageous before launching towards any destination.

It would add practical functionality to the system maps ability to display relative planetary positions and allow a player to be able to take advantage of any optimum launch time.

Edit: Also useful info if wanting to determine possible delivery times if on an in system mission ect. (see also issue 1420)

[Brianetta]

The engines on your ship are so powerful and fuel efficient that, in every case, the most favourable launch window is immediate. You're not embarking on years of interplanetary ballistic flight, and you're not attempting to complete the journey on a very restricted delta-V budget. Any waiting will cost you time.

Computing the ETA of an interplanetary journey is difficult anyway. An estimate is likely to be wrong by days, and getting the exact figure would require simulating the journey - an expensive way to come up with a figure like that.

[Baobobafet]

All true about ship engines for the most part (I guess until there is some huge variance in engine performance)' I didn't expect it would be hard to estimate some sort of ETA using the autopilot in some albeit streamed down version to do a quick simulation (even a basic distance at set speed) - but if it will be out by days ETA wise - that does seem rather pointless. Might as well have a table of some sort.

Too bad really since the system map seems like a great place to plan any trip from.

[mikehgentry]

Sometimes it's hard to know which planet to visit first.

I could imagine some kind of 'travelling salesman mode' to visually plan multi-stage journeys in the system orbit view being really handy.

If you double-clicked on a planet, it could draw a 'dotted line' from your present location to your selection, moving the planets' orbits ahead as it did so, then list the approximate distance and journey time on screen. Then if you double clicked on another planet, it could plot your course onward from there, keeping a running total of time / distance. There could be a key / button to reset to the beginning or wind back in stages, so you could examine different possible routes.

It wouldn't need to be terribly accurate to be useful I don't think - sometimes the difference between different routes between three or four bodies can be quite large, and as long as the distances / times were listed as 'projections' I can't imagine anyone being overly grumpy if they're wrong... :-)

[Brianetta]

Compared to the sort of acceleration of which your ship is capable, the orbital velocity of the planets is insignificant. It's enough to just look on the system orbital map. You can visit every inhabited body in Sol, and in the time it takes to do that only moons will have moved significantly.

[mikehgentry]

It would be more useful in larger systems, definitely. Nevertheless, a round trip in the Eagle in Sol-like systems can take 10 days, in which time planets do move appreciably... and there are starports on moons too!

[Brianetta]

Appreciably, but not significantly. None of them move far enough that you'd have to change your intended itinerary. Virtually nothing is more than an hour's flight away from where it was a week ago.

[mikehgentry]

Fair enough. It's one of those things I guess that might be a 'nice to have' in some systems. Which systems probably depends on how accurate it would be possible to make it, you have a sense of that and I don't...

Cheers.

[Brianetta]

We can plot ballistic paths, but realistically only as far as the next frame boundary. Even the autopilot doesn't know exactly where it will be while it flies; it constantly corrects to make sure that it gets to its destination, rather than planning a route ahead. It's likely to be one of those features that will only be added by somebody who wants it enough.

[tlhonmey]

So, calculating the "optimal departure" time is pointless given the powerful engines involved. But I'd like to point out that a convenient way to calculate approximate trip time between points lets you know the latest possible departure time that gets you there in time to fulfill a contract.

For example: If you know that it's a 24 hour trip to Mars, you know that you need to stop gathering transport contracts and head out at least 24 hours + time to deliver on the far end. This gets more important as the trip time approaches the contract time allowance so you don't accidentally grab contracts you have no possibility of completing.

The estimate doesn't have to be exact, just within, say, 10%.