[WEB APP] Launch Window Planner

[Dobrodav]

For real solar system there is a programm named "Trajectory Optimization Tool",that was created for Orbiter, it also allows multiple bodies in one flight calculations. It is maybe not the best one, i was just used it few years ago. Also there is other tools, like that, on orbithangar.com site.

http://www.orbithangar.com/searchid.php?ID=5418

[alexmun]

I've updated the Launch Window Planner to have greater accuracy in its delta-v calculations, particularly for bodies with relatively small spheres of influence. This should help those using maneuver node editors to execute more precise transfer burns. In the process I discovered that optimal (e.g. Hohmann) transfers from Laythe to Vall are not physically possible, so you will now see a section of that plot that is inaccessible (unless your parking orbit is 20km or more below the surface).

[Kryxal]

I wonder if the update might be why the KSP Launch Window Planner seems not to want to plot for me ... oh, I think the "Optimal" transfer type is broken, was trying to plot from Jool to Kerbin at 6 years, 30 days, aerobrake.

[NathanKell]

Hi alexmun! Great to see an update to this.

A question for you--what license is the planner released under? I'd like to make a version of it for RSS, and regex was interested in making one for the 6.4x Kerbol rescale....

[alexmun]

I wonder if the update might be why the KSP Launch Window Planner seems not to want to plot for me ... oh, I think the "Optimal" transfer type is broken, was trying to plot from Jool to Kerbin at 6 years, 30 days, aerobrake.

Thanks for the detailed bug report! It should be fixed now.

Hi alexmun! Great to see an update to this.

A question for you--what license is the planner released under? I'd like to make a version of it for RSS, and regex was interested in making one for the 6.4x Kerbol rescale....

It's licensed under Creative Commons BY-SA-NC, so feel free to fork it! All you should have to edit is the celestialbodies.coffee or celestialbodies.js files (and maybe change some of the defaults in porkchop.coffee from Kerbin/Duna to whatever is appropriate). If you change the name of the sun from Kerbol, there's a few other references you'd have to update.

[Kryxal]

Thanks for the quick fix! I only purchased KSP fairly recently, but this tool is a lifesaver for knowing good times to launch!

[alexmun]

Another quick update. I've added a "Refine transfer" button, which adjusts the selected transfer's ejection burn taking into account how your transfer orbit is affected by your origin body while you're leaving it's sphere of influence. This makes the calculated ejection burn details more accurate. The difference is pretty minor for planetary transfers, because the planet's sphere of influence tends to be quite small relative to the distance of the transfer. But the difference can be significant for transfers between moons.

[NathanKell]

Great! Thanks so much!

[AbeS]

Nathan I did some of the work for you, it is just missing the LAN, Arg of Peri and the Mean Anomaly of the moons

Here is the github

how do I test it alexmun?

EDIT: Figured it out, here is the link: KSP Launch Window Planner for RSS

Edited February 21, 2014 by AbeS

[regex]

Alexmun, I just downloaded the latest version of your planner, plugged in some values for my RSS 6.4:1 Kerbin system, and I'm getting some very weird results.

Here are the relevant lines that were changed:

CelestialBody.Kerbin = Kerbin = new CelestialBody(2.1687475458e024, 3840000, 86400, new Orbit(Kerbol, 13599840256, 0.0, 0, 0, 0, 3.14), 1);
CelestialBody.Duna = Duna = new CelestialBody(1.8487980356e023, 2048000, 102385.826, new Orbit(Kerbol, 132647393689.6, 0.051, 0.06, 135.5, 0, 3.14), 0.203);

When I first open the page, I get this:

Which seems a little odd since I know the transfer to Duna takes much longer than 94 days and that the optimal transfer takes place sometime around day 290. So I adjust the values and try the plot:

Which is wrong because I know that the transfer takes some 3.5km/s from experience.

I'm guessing from the plot that the orbital period isn't being calculated correctly?

E: I'll check when I get home that Kerbol has the correct mass and radius but I'm pretty sure I entered that. I'm using the values for our own Sun because making Kerbol 6.4 times as big is silly.

Edited February 27, 2014 by regex

[alexmun]

Hi Regex,

It looks to me like you updated Duna's orbit but not Kerbin's. In the code you posted Duna's semi-major axis is about 10x Kerbin's, which doesn't seem right.

[regex]

Hi Regex,

It looks to me like you updated Duna's orbit but not Kerbin's. In the code you posted Duna's semi-major axis is about 10x Kerbin's, which doesn't seem right.

LMAO. Damnit. Thanks, man.

[Superfluous J]

First off, I absolutely love this tool. I wish it was a mod, maybe a plugin for KAC

Anyway, until that wonderful day I have a request. The way I use this tool is, after I find the transfer I want I plug it into KAC as a raw time alarm. I copy all the goodies off the right hand side of the page and paste them into the text window for the alarm. That way, 2 weeks from now (real time. I play slowly) when the transfer window actually comes up I won't have to go regenerate everything on the page etc. It's all there, in the game waiting for me.

When I copy the text and paste it, though, it goes in like this:

Departure
Year 1, day 145 at 3:07:12
Arrival
Year 1, day 194 at 19:07:12
Time of flight
49 days 16:00:00
Phase angle
-40.86°
Ejection angle
151° to retrograde
Ejection inclination
-5.88°
Ejection ÃŽâ€v
1,087 m/s 
Transfer periapsis
9,023 Mm
Transfer apoapsis
13,338 Mm
Transfer inclination
0.65°
Transfer angle
234°
Insertion inclination
15.91°
Insertion ÃŽâ€v
1,625 m/s
Total ÃŽâ€v
2,711 m/s

And I edit it to go in like this:

Departure Year 1, day 145 at 3:07:12
Arrival Year 1, day 194 at 19:07:12
Time of flight 49 days 16:00:00
Phase angle -40.86°
Ejection angle 151° to retrograde
Ejection inclination -5.88°
Ejection ÃŽâ€v 1,087 m/s 
Transfer periapsis 9,023 Mm
Transfer apoapsis 13,338 Mm
Transfer inclination 0.65°
Transfer angle 234°
Insertion inclination 15.91°
Insertion ÃŽâ€v 1,625 m/s
Total ÃŽâ€v 2,711 m/s

Is there a way to make it so the text I copy looks more like the latter than the former? Maybe even a "copy to clipboard as text" button or something?

Edited March 14, 2014 by 5thHorseman

[cantab]

Now the release of .23.5 has given us a choice of two time systems, what does the launch window planner use?

[dlrk]

Does anyone have a config of this for RSS 10x Kerbol system? I downloaded the source, but I'm not sure of what values to change.

Thanks

[alexmun]

Now the release of .23.5 has given us a choice of two time systems, what does the launch window planner use?

Historically, the launch window planner has used Earth time. I've now added an option so you can use whichever time system

Does anyone have a config of this for RSS 10x Kerbol system? I downloaded the source, but I'm not sure of what values to change.

Everything you need to change is in the celestialbodies.js file. All values are in meters, kilograms, seconds or the appropriate combination thereof.

[goldenpeach]

I have a problem:

I made the program plot a transfer from kerb in(starting at 1000KM) to duna.

I double-checked everything but the plot isn't working: the trajectory wasn't going into Duna's SOI(I made mechjeb plot a course correction but the correction burn would have take roughly the same delta-v that I used for the initial transfer).

[cantab]

First thing to check is that you use the same time system for the planner as you do in the game.

Next thing may be that some mods confuse the angle from retrograde and the angle to retrograde (and likewise for angles from/to prograde).

[goldenpeach]

I used the same time in the game and the planner, and I use mechjeb(I put the number for the burn(prograde and normal) in the maneuver node editor.

I used the same method once for a transfer(to duna from kerb in) and it worked(I started at circular, 100km orbit), I switched to 100km orbit because it require less delta-v.

[phoenix_ca]

You didn't set the manoeuvre node to exactly the same time as in the planner, did you? Because if you did, depending on your vessel's orbit, it could be very far from the correct ejection angle.

[Superfluous J]

I used the same time in the game and the planner, and I use mechjeb(I put the number for the burn(prograde and normal) in the maneuver node editor.

I used the same method once for a transfer(to duna from kerb in) and it worked(I started at circular, 100km orbit), I switched to 100km orbit because it require less delta-v.

I don't know enough about MJ to help with that, but if you post a picture of the map mode showing your complete Sun orbit after you've set up your maneuver node(s) I may be able to help with whatever is wrong with the planned maneuver.

[Meithan]

Hi. First of all, I want to thank you deeply for writing this fantastic tool. I rely heavily on it for all my interplanetary missions.

I just have a small request.

Could the lower/upper delta-v limits for the porkchop plot be user-configurable (maybe under advanced settings)? Sometimes a few values have very large delta-v's, which makes the color map less useful for it becomes almost completely blue. Here's an example (Jool -> Kerbin transfer with midcourse correction and aerocapture at destination, departing from a 150 km orbit on Year 10 Day 1 at the earliest, Kerbin time):

As you can see, the upper limit of the plot is huge. I'd be more useful if the user could (optionally) set the limits, and have any value below the minimum simply be blue and any value above the maximum be red (or whatever colors are at the ends of the colormap).

Thanks!

[goldenpeach]

I don't know enough about MJ to help with that, but if you post a picture of the map mode showing your complete Sun orbit after you've set up your maneuver node(s) I may be able to help with whatever is wrong with the planned maneuver.

I *think* I know the problem: I did another launch window after the last one(I skipped it and I couldn't go back). I realized that that the trajectory was passing inside the SOI of another body, maybe that's the cause of the the problem.

[davidpsummers]

This looks like an excellent tool to help me rescue a lost ship stranded in orbit. But to do that I need to enter the orbit. Someone pointed me at the persistence file that has the orbital parameters for the ship. It has a Semi-major axis and Eccentricity that I had already calculated. Since those two are SMA and ECC in the file, I figure INC is the Inclination and LAN is the Longitude of Ascending Node. The only problem I have is the Argument of Periapsis. The remaining values are LPE, MNA, and EPH?

- - - Updated - - -

BTW, "Days from Epoch" means "days since UT started counting from zero"?

[Meithan]

. The only problem I have is the Argument of Periapsis. The remaining values are LPE, MNA, and EPH?

I believe LPE is the longitude of periapsis, MNA is the mean anomaly at epoch and EPH is the epoch itself (at which MNA is given).

The longitude of periapsis is the sum of the longitude of the ascendending node and the argument of periapsis:

https://en.wikipedia.org/wiki/Longitude_of_the_periapsis

BTW, "Days from Epoch" means "days since UT started counting from zero"?

I think so, yes.