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[1.8-1.12.x] Trajectories v2.4.1 (2021-06-27) : atmospheric predictions


Kobymaru
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It's such a weird bug lol! It's more annoying than problematic.

Is there a way to see the atmospheric trajectory before an SOI change? For example, planning a maneuver to return to Kerbin from the Mun, see the whole trajectory.

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22 hours ago, dlrk said:

Is there a way to see the atmospheric trajectory before an SOI change? For example, planning a maneuver to return to Kerbin from the Mun, see the whole trajectory.

That's probably beyond my math skills, @Kobymaru is the maths genius but I've not heard from him in a long while. If I get the time I'll see what I can do but wont be any time soon due to work :(

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@PiezPiedyPy

I"m not sure if you understood the feature/bugfix I was requesting there.

Currently (unless I'm missing something), when planning a maneuver with an SOI transition (return from Mun to Kerbin, for example), you can see the trajectory in body-fixed mode, just not the atmospheric affect on the trajectory (it seems to stop when it hits the atmosphere). Would completing the atmospheric trajectory through the atmosphere (like it would do without the SOI change) require new math?
 

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58 minutes ago, dlrk said:

Currently (unless I'm missing something), when planning a maneuver with an SOI transition (return from Mun to Kerbin, for example), you can see the trajectory in body-fixed mode, just not the atmospheric affect on the trajectory (it seems to stop when it hits the atmosphere). Would completing the atmospheric trajectory through the atmosphere (like it would do without the SOI change) require new math?

Because of the SOI transition, that might not be possible.  But you can see where it enters the atmosphere.  I'd say you can get a rough positioning before entering the SOI.  However, upon entering the SOI, you should plan for an immediate course correction burn to adjust the landing using the information from Trajectories if the rough positioning isn't sufficiently accurate.

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  • 2 weeks later...
10 minutes ago, Thorn_Ike said:

Hi, when will Trajectories be updated to 1.4?

It is.  I'm running KSP 1.4.5 and Trajectories vKSP1.4.2-v2.2.0, and don't have a problem.  Is yous not working?

The latest version is on GitHub, listed on the OP.

@Kobymaru, perhaps update the topic title?

Edited by Brigadier
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12 minutes ago, Brigadier said:

It is.  I'm running KSP 1.4.5 and Trajectories vKSP1.4.2-v2.2.0, and don't have a problem.  Is yous not working?

The latest version is on GitHub, listed on the OP.

@Kobymaru, perhaps update the topic title?

Ah, I just didn't bother since I saw the version was 1.3.

Thanks!

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6 hours ago, Brigadier said:

It is.  I'm running KSP 1.4.5 and Trajectories vKSP1.4.2-v2.2.0, and don't have a problem.  Is yous not working?

The latest version is on GitHub, listed on the OP.

@Kobymaru, perhaps update the topic title?

There is a newer version out. V2.2.1 on the GitHub and Spacedock.

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10 hours ago, BlackHat said:

There is a newer version out. V2.2.1 on the GitHub and Spacedock.

Yeah, thanks, I saw that when I was researching my response to Thorn_Ike.  I was going to try and find out why CKAN wasn't picking it up.

Edited by Brigadier
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1 hour ago, Brigadier said:

Yeah, thanks, I saw that when I was researching my response to Thorn_Ike.  I was going to try and find out why CKAN wasn't picking it up.

Hmm your right. I am still on 2.2.0 also. (I also use CKAN) And it looks like PiezPiedPy has done a lot of updates to it, maybe a new version will be out soon.

Edited by BlackHat
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  • 2 weeks later...
  • 2 weeks later...
On ‎11‎/‎11‎/‎2018 at 2:14 PM, dlrk said:

I don't believe it does, but to double check, does Trajectories account for thrust (when landing on airless bodies) or assume instantaneous burn?

It only accounts for drag and lift (you can specify AoA) while coasting for predictions. It'll update the prediction in real-time while thrust is engaged. (And the prediction is just what the path will be like if you STOP thrusting at that point. Remember, these are coasting predictions.)

It's meant for mainly atmospheric (re-)entry. The normal orbit lines are sufficient for airless worlds.

Lastly, I don't think there is any mod that accounts for thrust over time rather than instantaneous point thrust. The closest thing is/was a mod that broke down a long burn into multiple smaller, shorter burns. (I think MechJeb or PreciseNode did that. Don't quote me on that.)

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On 11/14/2018 at 12:01 AM, StahnAileron said:

It only accounts for drag and lift (you can specify AoA) while coasting for predictions. It'll update the prediction in real-time while thrust is engaged. (And the prediction is just what the path will be like if you STOP thrusting at that point. Remember, these are coasting predictions.)

It's meant for mainly atmospheric (re-)entry. The normal orbit lines are sufficient for airless worlds.

Lastly, I don't think there is any mod that accounts for thrust over time rather than instantaneous point thrust. The closest thing is/was a mod that broke down a long burn into multiple smaller, shorter burns. (I think MechJeb or PreciseNode did that. Don't quote me on that.)

Does this mean there is no way to get a prediction for a later stage? I dump my last engine in my last stage before re-entry, the prediction always jumps! Any way to figure out how it will?

Also is there any neat explanation of the AoA stuff?

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1 hour ago, MoridinUK said:

Does this mean there is no way to get a prediction for a later stage? I dump my last engine in my last stage before re-entry, the prediction always jumps! Any way to figure out how it will?

Also is there any neat explanation of the AoA stuff?

Correct: Trajectories only accounts for the CURRENT configuration of your craft. There's no option to make predictions for a later stage with a different set-up. (ANY mod that takes staging into account for predictions can get VERY complex. Just ask the MJ or KER devs.) The only thing you can do is launch the craft, cheat it into orbit, do a de-orbit burn, get it to the configuration you need it in, and test the re-entry. (TL;DR: Do a live test.)

For atmospheric bodies, Trajectories lets you set a AoA for the duration of re-entry based on I think the stock cut-off altitudes for situation transitions (i.e. Flying High vs Flying Low.) Or close enough to it. I think there's a third slider for REALLY close to the ground. The slider is quite rough, though. It's more like preset angles instead of a fine-grain adjustment slider.

In any case, setting/leaving it at zero with defaults assumes you're point directing prograde. Values other than zero is attitude relative to prograde. I think there is a setting to change this to horizon-relative, however. Of course, the orientation of your command part plays a role since that dictates the orientation of your craft relative to prograde.

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AoA Angle of attitude ok...

I try to come in bottom first, so facing retrograde as that's where the heat shield is! 
I do find the inability to plan landings really irritating!  lol

Trajectories is awesome though, but even when set to retrograde I don't impact in the right place, it's like it ignores the braking from the atmosphere which it's supposed not to do..
So I burn for re-entry, point retrograde as I tell Trajectories I will and then watch the impact crosshair move as I tear through the atmosphere... :( 

I'm not sure what I'm missing... 

 

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On 11/13/2018 at 4:01 PM, StahnAileron said:

It only accounts for drag and lift (you can specify AoA) while coasting for predictions. It'll update the prediction in real-time while thrust is engaged. (And the prediction is just what the path will be like if you STOP thrusting at that point. Remember, these are coasting predictions.)

It's meant for mainly atmospheric (re-)entry. The normal orbit lines are sufficient for airless worlds.

Lastly, I don't think there is any mod that accounts for thrust over time rather than instantaneous point thrust. The closest thing is/was a mod that broke down a long burn into multiple smaller, shorter burns. (I think MechJeb or PreciseNode did that. Don't quote me on that.)

The predictions take into account rotation of the planetary body, which definitely does help on airless worlds.  Particularly say if you have a base and want to land there.

 

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