# [WEB] Kerbal Transfer Illustrator, a mission planning tool

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Quick noob question, lets say I want to take a craft from low Kerbin Orbit and rendezvous with a comet in one of their crazy way-out-there orbits. What transfer is best? Ballistic or Mid-Course change? Also can you ELI5 what the difference between the Starting and Target Orbit Mean Anomaly is and how that would affect my plot?

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4 hours ago, Eleven said:

Quick noob question, lets say I want to take a craft from low Kerbin Orbit and rendezvous with a comet in one of their crazy way-out-there orbits. What transfer is best? Ballistic or Mid-Course change?

It depends on some of the particulars of the comet's orbit. If the inclination is low, there won't be much of a difference. Otherwise, it depends on exactly how the orbit is "tilted" relative to Kerbin's orbit. I'd try both options and pick whichever gives you better results.

4 hours ago, Eleven said:

Also can you ELI5 what the difference between the Starting and Target Orbit Mean Anomaly is and how that would affect my plot?

Mean anomaly at epoch is part of defining the timing of an object's position in its orbit. In case you're interested in what it represents...

The "epoch" is just a reference time in seconds (usually the current in-game time when an orbit is calculated).

"Mean anomaly" is a number that represents how far along an object is in its orbit in terms of the total time it takes to complete a full revolution. It's given in radians in-game and in the app, so 0 means the object is at the periapsis, and pi means the object is at the apoapsis. The mean anomaly of an orbiting object changes over time, as its position changes.

The "mean anomaly at epoch" is the mean anomaly at a particular time (the epoch), so its value doesn't change over time as long as the orbit itself doesn't change.

Changing the mean anomaly at epoch (or the epoch) keeps the "shape" of the orbit the same, but changes the times when the object passes through the periapsis. If you're starting in LKO and leaving Kerbin's sphere of influence during a mission, timing of your starting orbit likely won't result in any noticeable difference in the porkchop plot. The period of the starting orbit is rather short (~30 minutes), so you're departure times might change by a few minutes, but everything else would mostly stay the same.

For rendezvous with a comet, changing the timing of the comet would cause a horizontal shift in the porkchop plot and strongly affect the success of your mission. You might end up in the right place at the wrong time (e.g. at the comet's apoapsis, but the comet is near its periapsis), and you would end up missing the comet entirely. If you're on PC, I'd recommend loading the comet's orbit from your savefile so that you don't run into this problem. Unfortunately, I don't think it is possible to get the timing parameters for an orbit if you're playing on console, so you could 1) use the results from the app as a starting point and make large adjustments to the timing and position of your departure maneuver node, or 2) use the positions of the planets relative to the comet to approximate the timing parameters for the comet (making sure things in the app look similar to things in the game) in order to get a more accurate flight plan from the app.

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4 hours ago, theAstrogoth said:

It depends on some of the particulars of the comet's orbit. If the inclination is low, there won't be much of a difference. Otherwise, it depends on exactly how the orbit is "tilted" relative to Kerbin's orbit. I'd try both options and pick whichever gives you better results.

Mean anomaly at epoch is part of defining the timing of an object's position in its orbit. In case you're interested in what it represents...

The "epoch" is just a reference time in seconds (usually the current in-game time when an orbit is calculated).

"Mean anomaly" is a number that represents how far along an object is in its orbit in terms of the total time it takes to complete a full revolution. It's given in radians in-game and in the app, so 0 means the object is at the periapsis, and pi means the object is at the apoapsis. The mean anomaly of an orbiting object changes over time, as its position changes.

The "mean anomaly at epoch" is the mean anomaly at a particular time (the epoch), so its value doesn't change over time as long as the orbit itself doesn't change.

Changing the mean anomaly at epoch (or the epoch) keeps the "shape" of the orbit the same, but changes the times when the object passes through the periapsis. If you're starting in LKO and leaving Kerbin's sphere of influence during a mission, timing of your starting orbit likely won't result in any noticeable difference in the porkchop plot. The period of the starting orbit is rather short (~30 minutes), so you're departure times might change by a few minutes, but everything else would mostly stay the same.

For rendezvous with a comet, changing the timing of the comet would cause a horizontal shift in the porkchop plot and strongly affect the success of your mission. You might end up in the right place at the wrong time (e.g. at the comet's apoapsis, but the comet is near its periapsis), and you would end up missing the comet entirely. If you're on PC, I'd recommend loading the comet's orbit from your savefile so that you don't run into this problem. Unfortunately, I don't think it is possible to get the timing parameters for an orbit if you're playing on console, so you could 1) use the results from the app as a starting point and make large adjustments to the timing and position of your departure maneuver node, or 2) use the positions of the planets relative to the comet to approximate the timing parameters for the comet (making sure things in the app look similar to things in the game) in order to get a more accurate flight plan from the app.

NICE!

I do play on PC and loaded up my persistent file, here's the relevant info if you wanna look:

I entered the burns, but still don't quite get an encounter even after refining, but it's close. I think fiddling around with the final burn might eventually get me an encounter!

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1 hour ago, Eleven said:

NICE!

I do play on PC and loaded up my persistent file, here's the relevant info if you wanna look:

I entered the burns, but still don't quite get an encounter even after refining, but it's close. I think fiddling around with the final burn might eventually get me an encounter!

Great! I haven't done much testing with comets, but I think that when you're working with the really large distances of a comet's orbit and the really small size of the comet itself, sometimes even a floating point error (basically rounding error) can make it necessary to fine tune your maneuvers a bit.

You would likely need to make small course corrections even with a "perfect" result, since instantaneous maneuver nodes introduce some error anyways.

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• 1 month later...

I've thrown together an update that adds support for KSP2 save files. As with KSP1 saves, orbiting crafts can be loaded into the Transfer Planner, Flyby Planner, and/or Flight Planner after selecting your save file with the "Load Save File" button.

Unlike KSP1 saves, the comm signal strengths of crafts are not loaded from KSP2 saves. I'd need some assistance collecting the "partName" for each of the available antennas (and cockpits/probe cores) in the game and matching them with their corresponding signal strengths before I can put this together.

I noticed from the small amount of testing I was able to do that orbits calculated after maneuver nodes in KSP2 don't closely match those in the Flight Planner (which are the same as KSP1). The only example I have is a particular maneuver node for a vessel in LKO that raised its in-game apoapsis to 1,597 km, for which the app predicts an apoapsis of 1,623 km, an error of ~2%. This is either a bug, I'm misunderstanding what I can see of the new UI, or KSP2 has added finite burn calculations to its maneuver nodes (which would be really cool!).

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• 2 weeks later...

The multi flyby gave some crazy inaccurate orbit and rendezvous

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32 minutes ago, RaceToTheMun said:

The multi flyby gave some crazy inaccurate orbit and rendezvous

Would you mind sharing a link to the problem (press the “Get Link” button and paste here), or at least some details about your inputs? As it stands I’m not sure what the problem is.

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10 hours ago, theAstrogoth said:

Would you mind sharing a link to the problem (press the “Get Link” button and paste here), or at least some details about your inputs? As it stands I’m not sure what the problem is.

My starting orbit

Tried to copy the departure burn to nodes but it doesn't intersect with eve

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11 hours ago, RaceToTheMun said:

My starting orbit

Tried to copy the departure burn to nodes but it doesn't intersect with eve

Thanks for the info! I noticed that your starting orbit has a Mean Anomaly at Epoch of 242 rads. Did you type or copy/paste your starting orbit manually, or did you use the "Load Save" button in the app?

Unlike the other orbit parameters, the game uses radians (which are generally between 0 and 6.28) for this value, and it looks like there might be an extra/missing conversion between radians and degrees (242 degrees is about 4.2 radians). If you loaded your save in the app, there is likely a bug, although it seems I am not able to recreate it with any of my own saves. If this is the case, would you mind sharing your savefile with me via a PM, so I can figure out what causes the problem?

Also, if you want burn info that is accurate in game, make sure you press the "Refine Trajectory" button. It makes small changes to your trajectory to account for some things (like planet spheres of influence) that the original trajectory search ignores for the sake of speed.

Other than that, the timing of the maneuver is sometimes *slightly* off if, as in your case, you're planning a maneuver several years in the future. You might have better results if you timewarp to within at least a year of your maneuver, update the orbit information (the epoch and Mean Anomaly at Epoch will change), and recalculate your transfer/multiflyby. Otherwise, you should be able to manually adjust the timing of your maneuver node by a small amount to get an intercept.

Edited by theAstrogoth
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45 minutes ago, theAstrogoth said:

Thanks for the info! I noticed that your starting orbit has a Mean Anomaly at Epoch of 242 rads. Did you type or copy/paste your starting orbit manually, or did you use the "Load Save" button in the app?

Unlike the other orbit parameters, the game uses radians (which are generally between 0 and 6.28) for this value, and it looks like there might be an extra/missing conversion between radians and degrees (242 degrees is about 4.2 radians). If you loaded your save in the app, there is likely a bug, although it seems I am not able to recreate it with any of my own saves. If this is the case, would you mind sharing your savefile with me via a PM, so I can figure out what causes the problem?

Also, if you want burn info that is accurate in game, make sure you press the "Refine Trajectory" button. It makes small changes to your trajectory to account for some things (like planet spheres of influence) that the original trajectory search ignores for the sake of speed.

Other than that, the timing of the maneuver is sometimes *slightly* off if, as in your case, you're planning a maneuver several years in the future. You might have better results if you timewarp to within at least a year of your maneuver, update the orbit information (the epoch and Mean Anomaly at Epoch will change), and recalculate your transfer/multiflyby. Otherwise, you should be able to manually adjust the timing of your maneuver node by a small amount to get an intercept.

I just copy and paste the orbit manually from KSPTOT Initial orbit info. Like RAAN to Ascending node, etc

Also using Load Save doesn't do anything for me for some reason.  I even use the .SFS file

Might try to do the 3rd/4th paragraph tho after I get the first 2 problems out

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16 minutes ago, RaceToTheMun said:

I just copy and paste the orbit manually from KSPTOT Initial orbit info. Like RAAN to Ascending node, etc

That's part of the problem, I think. You'll need to convert your Mean Anomaly at Epoch from degrees (used by KSPTOT) to radians (used by KTI and the game).  For your case, 242.51106834404 degrees should become 4.232616615132491 radians.

17 minutes ago, RaceToTheMun said:

Also using Load Save doesn't do anything for me for some reason.  I even use the .SFS file

I'd like to fix this if I can! If you share your save file, I can take a look at why the app might be failing to read it.

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Here's the save file
Also is there an automatic way to put your starting orbit without doing it manually?

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1 hour ago, RaceToTheMun said:

Here's the save file
Also is there an automatic way to put your starting orbit without doing it manually?

Thanks! I think I've fixed the issue. It was caused by a few asteroids orbiting around some planets you'd added with mods, but I've made it so that the app ignores bodies that it doesn't have info for.

Now loading your savefile should let you select a craft to automatically fill its details in for a starting/target orbit. I was able to do it with "Looj", and it seems to work as intended.

For anyone who might come across this kind of issue in the future...

For stock planets or any of the planet packs build into the app (Outer Planets Mod, JNSQ, RSS), just select the solar system you'd like to use before loading your savefile, and everything should work correctly.

If you want to plan a mission to a modded-in planet, or you want to get info about something orbiting a modded-in planet, you have to set them up in the Solar System Editor before loading your save.

Edited by theAstrogoth
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21 hours ago, theAstrogoth said:

That's part of the problem, I think. You'll need to convert your Mean Anomaly at Epoch from degrees (used by KSPTOT) to radians (used by KTI and the game).  For your case, 242.51106834404 degrees should become 4.232616615132491 radians.

I'd like to fix this if I can! If you share your save file, I can take a look at why the app might be failing to read it.

Alright so I did all those, and here's how it went:
Did a timewarp near the date of departure and do another Search Trajectory, the Transfer is Ke-Ev-Ke-Jo btw. The maneuver mostly work. It almost intersects with Eve but I have to manually adjust the node. And well, it will flyby to Eve on the same date the Transfer illustator predicted. However, after that it says I need to do an Eve flyby burn node to Kerbin, but no matter how much I copy the nodes and replicate what's on the 3d graph, it won't intersect to Kerbin. So I let the craft orbit around Kerbol before intersecting eve and did another Search Trajectory. This time, I changed the starting orbit to around Kerbol now, and that kinda work. But it will only flyby on Eve.

After Eve flyby, I did an another Search trajectory but this only on Ke-Jo now. Which cost me 800 delta-v which is not that good, however it did surprisingly make a good flyby to Kerbin and Jool too! And I did a few adjustments and boom, I'm at Jool now.

Very useful transfer ngl, much more user-friendly compared to KSP-TOT. However there are some problems like what I said before and I was wondering what did I do wrong there.

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4 hours ago, RaceToTheMun said:

Alright so I did all those, and here's how it went:
...

However, after that it says I need to do an Eve flyby burn node to Kerbin, but no matter how much I copy the nodes and replicate what's on the 3d graph, it won't intersect to Kerbin.

...

However there are some problems like what I said before and I was wondering what did I do wrong there.

I can't say what specifically went wrong here, but here are a couple of thoughts:

One thing to keep in mind is that in KSP1, all maneuvers are considered instantaneous when predicting future orbits. This means that even if you execute a node *perfectly*, the resulting orbit won't be exactly the same as the one that was predicted. The app works the same way, so the only maneuver node that you'd reasonably be able to copy and paste without needing to adjust too much is the first one. All of the later maneuvers will either need to be manually adjusted or recalculated based on intermediate orbits.

When making manual adjustments for flybys, the most important thing to match is the periapsis of the flyby arc. You can add additional course correction maneuvers during your transfer orbits around Kerbol for fine-tuning your trajectory.

TLDR: errors in the app's calculations get worse for each successive maneuver, so manual adjustments are probably needed for any maneuver after the first one. Transfer/Flyby windows should still be correct in general.

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• 2 months later...

My planning (Kerbin>Eve>Duna flyby) :
https://imgur.com/AQ23L7F

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• 5 weeks later...

@theAstrogothReally nice tool, very nice UI, very clean looking, but I wonder if this tool supports Principia?

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21 hours ago, Aebestach said:

@theAstrogothReally nice tool, very nice UI, very clean looking, but I wonder if this tool supports Principia?

Principia doesn't change much deltaV values in most case, so yeah it works !

Only if you plan inside the Jool system it might get messed up (still not a lot I think), since Principia alters some orbits there, so that they're stable.

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