Youen

[1.2.2] Trajectories v1.6.6 (2017-01-25) : atmospheric predictions

903 posts in this topic

Before posting feature requests or bug reports, please read the FAQ.

FAQ

  • It works with stock aerodynamics and FAR
  • If the predicted trajectory seems inaccurate, check that you set the proper entry configuration in the GUI window (prograde or retrograde), and that you keep that orientation all the time
  • It is not possible at this time to predict a trajectory for a future stage. The prediction is made for the current vessel only. This is a most wanted feature but unfortunately also quite complicated to implement
  • If you see weird spirals or other crazy lines everywhere, double-check you didn't enable "body-fixed mode" by mistake
  • If you don't see the settings window and/or the button to show this window, make sure you look in the right place: it appears only during the game (i.e. not in space center), and only in map view
  • Players have reported it's compatible with deadly reentry (it doesn't estimate ablative shield weight loss during entry, but that usually makes no difference)
  • Someone reported it is not compatible with real solar system, but a very quick test showed it worked for me ; let me know your findings
  • Parachutes are not simulated (that's usually not a problem if you open it near the ground)
  • Compatible with Blizzy's toolbar (otherwise the icon goes in the stock toolbar)
  • Reportedly works with Rescaled Kerbin

 

 

Download

 

Mod description

The mod displays trajectory predictions, accounting for atmospheric drag, lift, etc. Works with the stock aerodynamic model, and also with Ferram Aerospace Research (FAR).

With this mod, you can

 

  1. choose very precisely the location where you'll crash (with a typical precision of about 6km, and if you survive it, you should be happy enough to still be able to walk that long)
  2. plan aerobraking maneuvers that can, for example, put you on intersection trajectory with another body (see point 1 about what you can do from there)

 

Keep in mind that this software comes without warranty of any kind, and in particular that it may or may not help you survive, reach a specific target, or anything at all. But it usually helps. At least, you can't void the warranty (because there isn't any).

 

User manual

See your predicted trajectory

 

  • Open the map view
  • This is it ; trajectory display is enabled by default, you have nothing else to do
  • White is the trajectory in space, red is the trajectory in atmosphere, the red cross is your impact point (that takes the body rotation into account to show the impact point on the terrain, this is useful both for bodies with and without atmosphere)

 

Disable the trajectory display

 

  • Click on the Trajectories icon in the stock KSP toolbar (or Blizzy's toolbar if it's installed) to display the main UI
  • Click "Display trajectory" to toggle it on/off
  • Click "complete" to toggle display of the complete trajectory (including parts where it is superimposed with the stock KSP trajectory)

 

Set a target point (nav ball guidance)

 

  • Adjust your velocity so that the red cross is located where you want to go
  • Click "Set current impact as target" to enable the green cross
  • Alternatively, there is a button to set the target on the KSC (works on Kerbin only obviously), or you can enter longitude/latitude
  • Go back in flight view, and notice the two new indicators on the nav ball
  • The square indicator shows where you need to point your craft at if you were exactly following the predicted trajectory
  • The circle indicator is a hint about the direction you should go to adjust your actual trajectory to reach the target (this is not necessarily where you need to point, what's important is the direction between the square and the circle, and the distance between them indicates how far you are from the perfect trajectory)

 

Body-fixed mode

Use this toggle to switch between the regular mode (similar to stock KSP orbits), or body-fixed mode. In body-fixed mode, the trajectory is displayed relatively to the body frame, following the body rotation. This mode makes sense for atmospheric or low terrain fly-by, and also to adjust a geostationary orbit. However, for most high orbits, it will just look funny. This can help you keep occupied for those 2-year-long planetary transfers, but try not to burn up all the fuel to see how it can make funny curved lines.

Manoeuver nodes

You can plan aerobraking or re-entry after manoeuvers, just place your nodes as usual and see the predicted trajectory. Keep in mind that you always place nodes on the stock trajectory, that might be very different from the predicted one, so you may have to place nodes at a point that have an effect somewhere else on the predicted trajectory (especially when planning landing on a body without atmosphere with body-fixed mode). Also, atmospheric prediction can happen only for the body you are currently orbiting, so you can't plan a Kerbin re-entry while you're still arround the Mun.

 

Support and Bugs

 

If you have questions and feedback regarding a current release, feel free to post in this thread.

Contributions

This mod is a community project! It is originally written by me (Youen) and is I'm also currently maintaining it.

The following people have already contributed to this project (in approximative order of last contribution)

  • Youen (Github neuoy)
  • Caleb9000 (Github CalebJ2)
  • Baleine (Github Baleine82)
  • atomicfury (Github sawyerap)
  • Kerbas_ad_astra (Github Kerbas-ad-astra)
  • Kobymaru (Github fat-lobyte)
  • mic_e (Github mic-e)

You want to be part of this list? I am very glad for all contributions of code, if they aid the goal of this Mod. To contribute, clone or fork my Repository on Github, have a go at the code and when you feel that your changes are mature enough to be included, send me a pull request! Also, it would be nice to let me know if you are working on something. And of course if you already contributed but I forgot your name, just tell me.

It's always best if you work on your "pet problem" - a bug that needs to be fixed or that you personally want to see implemented. If you don't have one, you could still grab something off the feature wishlist:

- Show trajectories in Flight view, like in this video (suggested by T.Lancer)

- Longer trajectory plotting - let the user decide how many orbits will be shown (suggested by drtedastro)

- Show trajectory after staging (suggested by Elthy, Entropius)

- Predict air brakes (suggested by DundraL)

 

For discussions about Mod internals (icky programming stuff and the likes), please head over to the development thread you can use this very thread (I think no one really used the development thread anyway).

Change log

See the Github releases page

This mod is under MIT license, feel free to look at the source code: https://github.com/neuoy/KSPTrajectories

Please post bug reports on the GitHub bug tracker, unless you don't have a github account or you're unsure it's a bug (in which case this forum is the right place to ask)

For the historic Mod thread, head over here.

Edited by Youen
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When this mod is actually going to work with atmospheric modifications is it going to work with real life planets scale?

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When this mod is actually going to work with atmospheric modifications is it going to work with real life planets scale?

Rumor has it that it does NOT work with RSS. You are very welcome to try and report your findings, though!

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Great to see it updated! I've yet to try this mod because I was waiting for an update, should be great with spaceplane landings. :)

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Great to see it updated! I've yet to try this mod because I was waiting for an update, should be great with spaceplane landings. :)

For space plane landings, the better your plane flies in atmosphere, the farther from the runway you want your projected impact location. Currently Trajectories does not account for glide paths/wings, so if you place it directly on the KSC you'll be gliding right over the top of it. I suck at plane design, despite how much I like flying them, so I'm not sure how early you want your impact location.

If your plane flies REALLY well, and not like a gliding brick, you can probably just put the X on KSC and dive towards the surface until you are close enough to the ground to glide in.

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I'm glad you took up the reins. This was a great addition. Please, please, please try to get FAR support working. I can't get anything to land where I want it to without this tool :)

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Definitely giving this a download when FAR support is ready.

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it would be awesome if you could get it showing trajectories outside of the map view. like this:

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it would be awesome if you could get it showing trajectories outside of the map view. like this:

Looks awesome. What about the guys Mod? Does it exist already?

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Trajectories is giving me errors along side other mods. Kerbal engineer and kerbal alarm clock.

Some parts are missing textures and on the load screen it says "module manager: 18 patches applied".

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Trajectories is giving me errors along side other mods. Kerbal engineer and kerbal alarm clock.

Some parts are missing textures and on the load screen it says "module manager: 18 patches applied".

I don't know about the errors, but the ModuleManager patches is normal.

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Trajectories is giving me errors along side other mods. Kerbal engineer and kerbal alarm clock.

Some parts are missing textures and on the load screen it says "module manager: 18 patches applied".

if the missing texture parts are white, thats a known bug "TGA loader" best use ATM (it fixes the loader bug) or convert the problematic textures to PNG

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Until FAR gets updated to work with this mod

That's going to be the other way around :-) There's nothing wrong with FAR (as far as I know), it's Trajectories that is not compatible with it (yet).

Edited by Youen

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That's going to be the other way around :-) There's nothing wrong with FAR (as far as we know), it's Trajectories that is not compatible with it (yet).

Well actually, this time it's really FAR ;) atomicfury found out that the Rho value passed to FARBasicDragModel.RunDragCalculation() does not get passed around internally. Ferram said he'd fix that in the next release.

I reenabled FAR support in the master branch and if people need it really badly and can't wait, I could make some builds of FAR and Trajectories with the hotfixes.

Edited by Kobymaru

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Oh by the way, any fix for the g-loading estimate? Currently the values just change really fast and is unreliable.

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I'm admittedly ignorant of what this Rho value is. How significant is this bug's effect on accuracy? And did this bug only come about recently, or was it always around since KSP 0.25?

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Oh by the way, any fix for the g-loading estimate? Currently the values just change really fast and is unreliable.

I'll look into it.

I'm admittedly ignorant of what this Rho value is. How significant is this bug's effect on accuracy? And did this bug only come about recently, or was it always around since KSP 0.25?

This bug came along with FAR 0.14.5 and it completely broke Trajectories with FAR installed. Just wait for the next FAR release and I will upload a Trajectories version with FAR enabled.

Also, ÃÂ (spelled rho) is the atmosphere density and very relevant to drag calculations. But this kind of math is best left to Ferram4 ;)

Edited by Kobymaru

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About the g-loading bug, if I remember correctly, it happens since incremental trajectory comptation is implemented, because the current value is displayed (from the partial computation that is still in progress), instead of caching the value from the previous completed computation. I think I already fixed it after 1.0 release, but I didn't make a release with the fix. Not sure to remember correctly though, that was some time ago.

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I really like this mod, although I kinda miss an option to disable the far/near checks.

I know it will not be accurate if I use NEAR and disable the adjustments but I would like to have this problem to deal with.

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Oh by the way, any fix for the g-loading estimate? Currently the values just change really fast and is unreliable.

Thanks the hint, I fixed it in the repo and the fix will be included in the next release.

About the g-loading bug, if I remember correctly, it happens since incremental trajectory comptation is implemented, because the current value is displayed (from the partial computation that is still in progress), instead of caching the value from the previous completed computation. I think I already fixed it after 1.0 release, but I didn't make a release with the fix. Not sure to remember correctly though, that was some time ago.

Thanks, I found it. Also, "A body in free fall experiences "0-g"" as Wikipedia puts it, so I subtracted the gravitational pull from the acceleration.

I really like this mod, although I kinda miss an option to disable the far/near checks.

I know it will not be accurate if I use NEAR and disable the adjustments but I would like to have this problem to deal with.

It's not about accuracy. There is a bug in FAR and if you use Trajectories with it, your game will lock up completely. Please wait until the next FAR/Trajectories release, then it will be reenabled. If people need it badly, I could post a prerelease and a recompile of FAR 0.14.5.1.

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People need it badly! :) Visited the thread just to see an option to enable it with FAR.

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