Transfer window visualization

[robogoofers]

The stock game needs an interface for planning interplanetary missions. I currently use external transfer window planners to find optimal dates, but the stock game just leaves players high and dry after they get to the Mun and Minmus. the built in tools are pretty poor for trying to plan something that may be kerbin-years away.

Even without a visulization in the map screen, just having contract missions offered around the window would be great. I may blow past a window to Eeloo because i'm focused on Duna and never expect a Eeloo window to open up.

Another idea is a "days to X Transfer window" countdown in the tracking station that could be a further upgrade option.

[pandaman]

Hi @robogoofers , welcome to the forums. 

I don't think you'll get many objections to that suggestion.  In game mission planning tools are often mentioned as a necessity. 

In case you aren't aware a couple of mods - Kerbal Alarm Clock and Transfer Windows Planner (often referred to as KAC and TWP) both work within game, so you may find it helpful to check them out. Incidentally the creator of these is now on Squad staff.

[Superfluous J]

Great first post there, @robogoofers. I totally agree.

A while ago I suggested something similar, a "Mission Planning Node" that works just like a maneuver node, but you put it on planet and moon orbits. You could put one on Kerbin's (or any other world's) orbit in the tracking station (and maybe even in map mode) and it would work just as if that world was a ship. You could drag it out to touch Duna's orbit, drag it around its own orbit of the sun, get your encounter just like you would going to Mun from LKO with maneuver nodes, and then when you get that encounter, a built-in Kerbal-Alarm-Clock type interface would alert you when you were getting close to the transfer window that YOU found, using in-game tools.

Maybe some day...

[eddiew]

+1000

[Alshain]

I agree, however "transfer windows" employ a time vs delta V approach and since KSP doesn't show you Delta V it is a moot point.  I also think KSP should show you Delta V, but until they do there is not much point in a transfer window.

[Red Iron Crown]

8 minutes ago, Alshain said:

I agree, however "transfer windows" employ a time vs delta V approach and since KSP doesn't show you Delta V it is a moot point.  I also think KSP should show you Delta V, but until they do there is not much point in a transfer window.

I agree about a delta-V meter being desiable, but a transfer window visualization is useful with or without it. It's not easily discoverable when the most fuel efficient times to transfer are, and those times are better whether you're calculating dV or just slapping tanks together.

[Alshain]

19 minutes ago, Red Iron Crown said:

I agree about a delta-V meter being desiable, but a transfer window visualization is useful with or without it. It's not easily discoverable when the most fuel efficient times to transfer are, and those times are better whether you're calculating dV or just slapping tanks together.

I disagree.  Transfer window planners are for planning Delta-V.  An approximate window when it will be more efficient in general is easy to identify using the map mode if you know what you are doing, and like much of the gameplay that is simply a matter of educating yourself.  If that was all they wanted to do, they could simply add KSPedia pages denoting the phase angle for each planet.

Edited September 8, 2016 by Alshain

[Red Iron Crown]

1 minute ago, Alshain said:

I disagree.  Transfer window planners are for planning Delta-V.  An approximate window when it will be more efficient in general is easy to identify using the map mode if you know what you are doing, and like much of the gameplay that is simply a matter of educating yourself.

Please describe this method of finding approximate windows without external tools like a list of phase angles. In my experience it's incredibly tedious to trial and error windows, and the only stock method of which I am aware is awfully awkward and involves stacking nodes.

Delta-V cost is certainly a useful part of a transfer window planner but the date is the critical one, the one that is useful with or without a delta-V meter.

[Alshain]

2 minutes ago, Red Iron Crown said:

Please describe this method of finding approximate windows without external tools like a list of phase angles. In my experience it's incredibly tedious to trial and error windows, and the only stock method of which I am aware is awfully awkward and involves stacking nodes.

I can for most of them, I haven't fully educated myself on Dres or Eeloo, but Moho is about 110 degrees in front of Kerbin, Eve is 55 degrees behind, Duna is 45 degrees in front, Jool is 115 degrees in front.   I have those memorized, I used no tools.

 

[Capt. Hunt]

In the past the devs have said that they don't show delta-v or predict transfer windows in order to encourage the user to figure out the math behind them through trial and error.

[Red Iron Crown]

12 minutes ago, Alshain said:

I can for most of them, I haven't fully educated myself on Dres or Eeloo, but Moho is about 110 degrees in front of Kerbin, Eve is 55 degrees behind, Duna is 45 degrees in front, Jool is 115 degrees in front.   I have those memorized, I used no tools.

 

From where did you memorize them? I learned them from a list someone smarter than me made and shared. Would it be bad to have such a list in Kerbpedia, even if there is no dV meter?

16 minutes ago, Capt. Hunt said:

In the past the devs have said that they don't show delta-v or predict transfer windows in order to encourage the user to figure out the math behind them through trial and error.

I can see trial and error being fun for some people, but I don't think a lot have deduced the math that way. I've played a lot of KSP and have learned some of the math involved but none have I deduced myself, all of it I learned by looking it up or help from people here. Best most people will get through trial and error is rough rules of thumb, unless they are as bright as Kepler or Newton. If the goal is to get people to learn the math then ideally the game would show more of it if they go looking.

[Superfluous J]

41 minutes ago, Capt. Hunt said:

In the past the devs have said that they don't show delta-v or predict transfer windows in order to encourage the user to figure out the math behind them through trial and error.

I don't remember a dev saying any such thing. My only memory is HarvesteR hemming and hawing at the idea, concerned that it would ruin the "Magic" of the game.

[Alshain]

2 minutes ago, Red Iron Crown said:

From where did you memorize them? I learned them from a list someone smarter than me made and shared. Would it be bad to have such a list in Kerbpedia, even if there is no dV meter?

1. I originally learned them from here.  2. Yes (or no, not a bad thing), that's why I said that an hour ago.

Edited September 9, 2016 by Alshain

[Red Iron Crown]

Just now, Alshain said:

Yes, that's why I said that an hour ago.

Sorry, missed your edit, I was composing.

I guess it's a difference of definitions. I'm thinking of "transfer window visualization" as anything that gives info about the windows to the player in game, which it seems we both agree is desirable, while I think you're thinking of more complex tools like the web ones or a porkchop plotter. I'd agree the latter ones are not overly useful without more dV info.

[Alshain]

@Red Iron Crown  Yeah I guess you could say a KSPedia is a visualization, I just think of a visualization as much more than static numbers on a page though.

Edited September 9, 2016 by Alshain

[Red Iron Crown]

Certainly something more visual for angles in map view would be better. I'd love it if when selecting a target the area on the target's orbit it would have to be for a good transfer right now was highlighted, and that area moves as the origin body moves. Warp until the target is in that zone and it's a good time to go.

[Alshain]

3 hours ago, Red Iron Crown said:

Certainly something more visual for angles in map view would be better. I'd love it if when selecting a target the area on the target's orbit it would have to be for a good transfer right now was highlighted, and that area moves as the origin body moves. Warp until the target is in that zone and it's a good time to go.

That is a neat idea but it wouldn't move, it wouldn't need to move.  The position of the proper phase angle will be the same for the entire orbit of the fastest moving planet.  It would be very similar to how the closest approach markers work now, only instead of the position of your craft and the target craft, you are marking the position of the parent body and the target body when the phase angle is correct.

I wonder if someone could make this into a mod?  Just to see how well it would work.  I'm not skilled enough with the API myself.  I know KAC/TWP has a way to visualize it's results phase angles, it could be similar to that but instead, just the optimal angle.  The porkchop graph without DeltaV would be unnecessary.

Edited September 9, 2016 by Alshain

[mattinoz]

If we had Maneuver nodes that could be place on the orbit then those nodes aren't giving away the best transfer window but still give us a more visual trial and error tool for finding transfers in game. Give you could pretty much get a transfer anywhere.

I don't see how effects the playful nature of the game just bring the errors more hands on.

[Diche Bach]

I would've thought that the "best" time would fluctuate more than a simple "when the angle between the two bodies is at X." Doesn't that sort of require that two bodies are in synch with their orbital periods?

For example, Voyager 1 and 2 made use of a rather rare alignment of Jupiter, Saturn and Neptune in order to escape the Sol System. I forget now but, I want to say that particular alignment won't recur for a very long time, hundreds of years or so?

Do most players just brute force their way to the outer planets without using gravity assists? I have never got that far with the game, but sort of figured that is how its done, given it it how it is done in real life.

For Duna, I reckon I'd try to get a couple gravity assists off of Mun, and then one more off of Kerbin (maybe just one and one) and then strive for the angle thing Kosmonots site refers to. I love doing gravity assist maneuvers and wish I understood the maths at an intuitive level if not a technical level better. You can literally get to Minmus for the same dV cost as a trip to Mun, an I reckon if you know what you are doing you could get to Duna for a little bit more than the cost of a trip to Mun too.

 

[Superfluous J]

8 minutes ago, Diche Bach said:

I would've thought that the "best" time would fluctuate more than a simple "when the angle between the two bodies is at X." Doesn't that sort of require that two bodies are in synch with their orbital periods?

For example, Voyager 1 and 2 made use of a rather rare alignment of Jupiter, Saturn and Neptune in order to escape the Sol System. I forget now but, I want to say that particular alignment won't recur for a very long time, hundreds of years or so?

Do most players just brute force their way to the outer planets without using gravity assists? I have never got that far with the game, but sort of figured that is how its done, given it it how it is done in real life.

For Duna, I reckon I'd try to get a couple gravity assists off of Mun, and then one more off of Kerbin (maybe just one and one) and then strive for the angle thing Kosmonots site refers to. I love doing gravity assist maneuvers and wish I understood the maths at an intuitive level if not a technical level better. You can literally get to Minmus for the same dV cost as a trip to Mun, an I reckon if you know what you are doing you could get to Duna for a little bit more than the cost of a trip to Mun too.

 

Voyager's route was a bit more complex than just "getting to another planet." They had to arrive that that planet at such a time and in such a way that they'd then be propelled to another planet's orbit, to arrive there at the time the other planet would be there as well. And then they had to repeat that a couple times.

To just get to another planet, though, you only have to leave your planet at the right time so your ship will end up at the other planet's orbit when the other planet will be there, which happens ... well not once a year but ... well it's complicated because both planets are moving. But each time the planets are a certain angle apart with respect to the Sun. It's always that same angle (ignoring orbital eccentricity).

So in short, to go to Duna you can always leave when Duna is ahead of Kerbin in its orbit, and the phase angle is about 45 degrees. It makes Duna easy to get to because we can visualize 45 degrees pretty accurately.

[Alshain]

@Diche Bach There is a small range, Duna could have a good transfer between 35-45, maybe even 50 degrees.  However, in the grand scheme of things it won't make much of a difference, you can see the total Delta V in the images below.   It does not require the same orbital period, just an angle in relation to a fixed point... the sun.

Spoiler

 

Spoiler

Spoiler

Spoiler

As for gravity assists, they can be done, it's painful with the stock tools we have though.  Remember, you don't just need the gravity assist... you have to find an encounter afterward.

Edited September 9, 2016 by Alshain

[Daveroski]

I would have settled for this which I suggested a while ago.

 

[Diche Bach]

I wish there was a simple tool to tell how much dV has been gained/shed from a gravity assist.

[eddiew]

1 hour ago, Diche Bach said:

I wish there was a simple tool to tell how much dV has been gained/shed from a gravity assist.

Best approximate is to check your velocity as you enter the SoI, and as you leave it   Of course, you may have just changed direction and be continuing at the same scalar speed you always were... 

Although thinking about something like a Tylo assist, it can easily cost a thousand or more m/s to get into Jool orbit - or exactly none if you get the Tylo intercept right  

[Diche Bach]

@eddiew Thanks man. Deserved a Like, but I already used up my allowance for today.

Looking at the dV table on Wiki, I think perhaps I'm not getting as much out of my Mun flybys as I was thinking I was.

Anyway, on topic: I'm definitely totally in favor of updates/improvements which enhance the existing flight planner and add additional journey and manuever planning tools. A "transfer window" visualizer would be sweet. Something that made gravity assists a bit less of hunt and peck would be sweet.

Especially when working around Kerbin after a career campaign is well underway (lots of misions, lots of sats, lots of debris) I find the inability to turn stuff OFF in the flight planner to be a gigantic pain. Yes I know you can turn off whole ship classes, but why not all of a class EXCEPT "this one?" And why can those damn waypoint markers from missions not be turned OFF!? And when I'm trying to get a redezvous, why can I not turn off those damned Apoapsis/Periapsis drop downs? And why no AN/DN markers by default? Sometimes you just want to get a particular inclination relative to equatorial, and not relative to a moving target. Why is setting the object you are orbiting as "the target" so obscure? (pretty sure it can be done, but it just seems to be some random keystroke somewhere).