[old thread] Trajectories : atmospheric predictions

[Kobymaru]

Hey @Youen, how hard would it be to add the "target" not only from the current impact point, but also the target vessel (if it is landed) or a particular waypoint?

 

16 hours ago, dlrk said:

Would it be possible for Trajectories to display the deviation of the projected landing point from the target?

That would also be pretty cool.

[Tyko]

Trajectories calculates point of landing based on the current craft, but when I'm planning a pod re-entry I still have the braking engines and fuel attached so I can drop my PE. After the PE is set, I stage the engine and tank - which changes my projected landing point.

The FAQ says Trajectories can't project future stages. Are there any best practices that others are using to work around this?

Edited January 12, 2017 by Tyko

[dlrk]

3 hours ago, Tyko said:

Trajectories calculates point of landing based on the current craft, but when I'm planning a pod re-entry I still have the braking engines and fuel attached so I can drop my PE. After the PE is set, I stage the engine and tank - which changes my projected landing point.

The FAQ says Trajectories can't project future stages. Are there any best practices that others are using to work around this?

 

You can get a rough estimate with Trajectories before staging, and then after staging use angle of attack, and RCS burns to get the landing point where you want it

[Agustin]

How can I know where am I going to land on no atmosphere planets? I think this mod is already able to do that but isn't enabled somehow...

[Li0n]

28 minutes ago, Agustin said:

How can I know where am I going to land on no atmosphere planets? I think this mod is already able to do that but isn't enabled somehow...

Tick the "complete" checkbox, in trajectories menu, in the map view. Your orbit line should go white and a red cross appear on the planet surface.

[Kobymaru]

Hello Friends of the Precise landings,

in the absence of Youen, I have updated the Trajectories mod.
The targeting interface is now actually useful, you can:

• Target landed vessels
• Target Waypoints
• Show the distance between the current impact point ant the target

Additionally, the mod is finally "officially" compatible with KSP 1.2.2.

ps.: No pics, no clicks:

 

I have contacted Youen so that we may see an official release soon. In the meantime, you can grab the updated DLL from here:

https://github.com/fat-lobyte/KSPTrajectories/releases/download/v1.6.6-Kobymaru1/Trajectories.dll

Please download and test. Have fun, and happy landings!

[Youen]

Thanks @Kobymaru for these improvements

I've published a new package that contains the DLL you built (I don't have the latest version of the game installed here so I didn't recompile) on github.

Since I didn't reinstall the game, I also didn't test anything. So let me know if everything works fine with the package I uploaded, and then I'll update on SpaceDock so that players with managed mods (CKAN and AVC) will get the updated version as well.

[Jebs_SY]

@Youen

Thx for your effort.  Do you also put that release on spacedock and change compatibility to 1.2.2, so that CKAN picks it up? CKAN could also pick it up from github, however, then the ckan-reference would need to be changed from the CKAN guys, if you like CKAN to do that.

Edited January 18, 2017 by Jebs_SY

[dlrk]

Thanks very much, @Kobymaru and @Youen.

Kobymaru, if you don't mind me asking, a few suggestions:

Separate display of latitudinal and longitudinal deviation

Allow display of the trajectories UI in flight view.

Allow the 'dot' to be selected as a maneveur node.

Thanks!

Edited January 19, 2017 by dlrk

[Rohaq]

I've unzipped the 1.2.2 version from Github and... I don't seem to have a Trajectories button? It definitely shows up in my loaded mods on the title screen:

Edited January 21, 2017 by Rohaq

[Li0n]

8 hours ago, Rohaq said:

I've unzipped the 1.2.2 version from Github and... I don't seem to have a Trajectories button? It definitely shows up in my loaded mods on the title screen:

Have you checked the available button in blizzy's toolbar ?

[Youen]

@Rohaq Indeed, it seems you have blizzy's toolbar installed, which means Trajectories will be available only there, and not in the stock toolbar. If you don't use blizzy's, you could uninstall it, in which case Trajectories would go in the stock toolbar instead.

I'd like to know if someone can confirm the package published on github works fine? So that I can also publish it on spacedock, and update the online AVC version (which will notify players using the previous version they can update, but I'd like to have it tested first).

[Rohaq]

You're right, I can't believe I didn't notice that. Thanks!

[linuxgurugamer]

@Youen

You didn't update Spacedock with 1.6.6

[Youen]

Well, I'm going to assume the latest version works fine since no one complained. Now published on SpaceDock, and AVC updated as well.

[dlrk]

Hey, Kobymaru, Youen,

Sorry to ask again, but judging by the last update I figured it might be possible, I have a few small feature requests that really would be an enormous help if implemented:

Display Trajectories window in flight scene.
Display latitudinal and longitudinal deviation separately in trajectories window.
Link 'dot' to maneuver node, to fly reentry automatically and/or display 'dot and square' path information in other window.

Thanks!

[Kobymaru]

 

Quote

Display Trajectories window in flight scene.

That might be a consideration. But, what is the use case for that? What would you do with the information? What is it that you currently can't do without this feature? Why can't you just use it in the Map View Scene?

 

Quote

Display latitudinal and longitudinal deviation separately in trajectories window.

That sounds technically feasible, but it would clutter up the UI for small benefit. Again, what is the use case for that? What would you do with the information? What is it that you currently can't do without this feature?

I don't know about you, but I find "latitude/longitude delta in fractions of degrees" a very unintuitive unit, compared to just kilometers and the visual information of the impact point vs target.

 

Quote

Link 'dot' to maneuver node, to fly reentry automatically and/or display 'dot and square' path information in other window.

I don't quite understand this one.

Edited January 30, 2017 by Kobymaru

[dlrk]

Kobymaru,

Thanks for the reply, I'm sorry if I was a bit obtuse, or didn't make the uses for these features clear.

For displaying the Trajectories window in the flight scene, the use would be flying a reentry and landing without changing scenes, being able to see heating, altitude, attitude, terrain etc.  Basically, what I can't do right now is fly the reentry while adjusting attitude for targeting, being able to see temperature on parts, and see the terrain and target. This would truly be an enormous for targeted atmospheric reentry and landing.

For displaying latitudinal and longitudinal deviation in the Trajectories window, you're absolutely right that lat/lon Δ in fractions of degree would be useless. What I was suggesting was displaying deviation to the e/w and n/s of the target in km/m. This would allow atmospheric reentry/landing to be controlled easier and more precisely. For example, if you see that you're deviating to the west, you could yaw east. As it is now, you can see that your getting further from your target, but not in fine detail (since the map view is coarse), except for the square and dot indicator on the navball, which is hard to see, and often blocked by the pitch indicator

 

Quote

 

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)

 

--That's description of the square and dot thing I was talking about. I'd like the dot to be able to be used as a maneuver node, so that rather than manually following it, MJ could do it in node mode.


Thanks for reading, and considering these requests

Summary: I can land perfectly on target with Trajectories, but I have to switch back and forth between flight and map view. If a window in flight view was available that provided more information, this would be much easier,

Edited January 30, 2017 by dlrk

[Kobymaru]

14 hours ago, dlrk said:

Thanks for the reply, I'm sorry if I was a bit obtuse, or didn't make the uses for these features clear.

No worries.

Quote

For displaying the Trajectories window in the flight scene, the use would be flying a reentry and landing without changing scenes, being able to see heating, altitude, attitude, terrain etc.  

Oh, I see. Yeah, that is kind of nice. I can implement that.

However what would be best is to actually draw the Trajectory in the flight scene - but that's way above my paygrade  

 

Quote

For displaying latitudinal and longitudinal deviation in the Trajectories window, you're absolutely right that lat/lon Δ in fractions of degree would be useless. What I was suggesting was displaying deviation to the e/w and n/s of the target in km/m.

...

For example, if you see that you're deviating to the west, you could yaw east.

Oh, I like this actually! Yes, I will do that when I have time  Could you create an Issue with a description on GitHub? You can copy-paste parts if your forum post.

 

Quote

I'd like the dot to be able to be used as a maneuver node, so that rather than manually following it, MJ could do it in node mode.

I don't think that's possible. The deviation from the flight path is continuous, but a maneuver node is a one-time velocity change. I have no idea how one would hook those two up.

[Kobymaru]

Dear Trajectories users, I think we might have a bigger problem here.

I just did a simple test with a single part, a Mk1-Command Pod, and the Predicted impact point before entering the Atmosphere deviates by about 90 km from the final actual impact point

(Yes, the correct Orientation has been set).

This points to a bigger issue with calculations, and kind of defeats the purpose of this plugin.

 

Here is a GitHub issue: https://github.com/neuoy/KSPTrajectories/issues/84

Could someone help to reproduce this and report back here? When you did, I think we should summon the great Youen, because I do not have the deep code knowledge needed to fix these kind of things.

[dlrk]

Kobymaru,

I tested your save, and also tested with an Mk1-2 pod with a heatshield attached.

It looks like the inaccuracies start to accumulate in the upper atmosphere, and decrease as the atmosphere thickens, more or less becoming accurate around 45km. Pitching up with the 'dot', and monitoring the deviation allows an accurate reentry to be flown, so it's not a huge problem, IMO. I was using the FAR dev build, so if you also are, it might be an FAR issue. To me it definitely seems like a minor bug, since it can be resolved by pitching to control reentry,

[danielboro]

i consider a 90Km miss from orbit to be dead on

[Youen]

The prediction used to be less than 10km wrong (more around 5km) for simple crafts and "classical" reentries (like 1/4 orbit inside the atmosphere, starting from LKO), so I guess something changed in the game and the mod needs to be updated (again...)

Unless you see this deviation using FAR ? In which case I don't know what would be the problem because FAR exposes a method that should remain accurate even when FAR internal model is modified.

Edited February 1, 2017 by Youen

[dlrk]

I see that deviation with FAR, but if you pitch as needed in the upper atmosphere, it's straight on target

[tg626]

I came here to share my experience with inaccurate landings, but it seems I'm not alone.  I don't have measurements handy, but I started with a predicted landing out in the water almost a "KSC Contient width" to the east of KSC, and wound up just west of KSC on land...  I think that's more then 90km...

Granted I'm using BDB's Hermes capsule, but since the Mk1 is doing off target landings, I think I'll watch for and update on that...  Are some settings better then others for these ballistic capsule re-entries?  It's a little sad that a bunch of Humans could calc this out without computers, but we can't get it with them and simplified physics... (That's not a jab at the mod author - I saw Hidden Figures a short time ago...)