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[old thread] Trajectories : atmospheric predictions


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That MAY be an issue with FAR itself. I have had the same issue and have never used this mod. Maybe take a look over at the FAR thread?
It is a FAR issue. One supposedly fixed in tihe DEV version.

Cheers guys. Only started using FAR last week.

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Great mod but causes too much lag

Can you give more details please ? In particular, when the game is lagging, do you have the red atmospheric trajectory correctly rendered ? Do you see white messages on the right of the screen ? Do you use Ferram Aerospace Research ? Does it lag even when your orbit doesn't enter atmosphere at all ?

The mod certainly adds some overhead to the game, but it shouldn't be a problem on most computers (if it is, the game probably was already lagging, the mod just makes it lag a bit more). That is unless you are experiencing some kind of bug, which I'd like to know to be able to fix it.

Thanks.

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It's integrated in the stock toolbar since v0.1.1

For those that still use the first published version, I suggest upgrading, some annoying issues have been fixed. Also, please indicate which version you use when posting bug reports :-)

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Downloading now and going to test, if this all works as described and doesn't cause any noticeable performance hit then you are my new hero!!

I've wanted something like this for a long time but don't have the skills to try and code it myself, always been told to just use mechjeb but I personally really don't like MJ, it always causes lag when I put the part on my ship :/

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I'm the author of the StageRecovery addon and this looks awesome! I have considered adding similar features to StageRecovery but it's always been too much work to do for me at the moment. If you ever decide to open up any of this as an API for other mods to use, I would love to be able to get the predicted lat/lon for landing and maybe the maximum velocity of a piece of debris/dropped stage. The lat/lon would be for determining the proper recovery value and the max velocity/speed would be for estimations of whether a vessel would be destroyed by Deadly Reentry (StageRecovery currently does this but since the atmosphere isn't actually changing the velocity, just gravity, the velocity at destruction is far too high).

Would it be possible to assume the orientation is the one with the least drag?

I'd also love to see this, or an extension of this, do aerobraking while on time warp.

Even if you can't do any of that, this is still awesome!

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This sounds very useful indeed. A more informative title may be in order, such as "Atmospheric Trajectories", but all in all I'm certain this mod will do well.

Edit: Oh, does it work well with Stock Drag Fix also?

Not yet, but it's certainly possible.

Would it be possible to assume the orientation is the one with the least drag?

What about when you have a cone shaped capsule coming in backwards? (heat shield first)

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What about when you have a cone shaped capsule coming in backwards? (heat shield first)

My comment was meant to be in the specific case of dropped stages, which are generally uncontrolled and are not going to remain in the point of unstable equilibrium you propose for long. If you care very much about your unattended stages which are aerodynamically unfavorable, you should probably land them manually (and most cases you won't need a heat shield for sub-orbital trajectories where you wouldn't be able to manually land).

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Can you give more details please ? In particular, when the game is lagging, do you have the red atmospheric trajectory correctly rendered ? Do you see white messages on the right of the screen ? Do you use Ferram Aerospace Research ? Does it lag even when your orbit doesn't enter atmosphere at all ?

The mod certainly adds some overhead to the game, but it shouldn't be a problem on most computers (if it is, the game probably was already lagging, the mod just makes it lag a bit more). That is unless you are experiencing some kind of bug, which I'd like to know to be able to fix it.

Thanks.

I am using FAR. Lag pops in at random and really chugs the game for a bit then it speeds up again. It's happened to me during launch, in orbit and reentry. The white messages on the side only appear all the time and not always does it cause lag.

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I am using FAR. Lag pops in at random and really chugs the game for a bit then it speeds up again. It's happened to me during launch, in orbit and reentry. The white messages on the side only appear all the time and not always does it cause lag.

What white messages do you get ? Is it better if you turn-off auto-update ? It may be that your craft has an unstable aerodynamic profile. What I mean by this is that the aerodynamic behavior would change a lot when the ship is deformed due to accelerations or other factors. If you turn auto-update off, the aerodynamic profile won't be refreshed automatically, so you'll have to click the "update now" button after stage separation for example. But at least it won't update each frame as I suspect is happening to you.

Edited by Youen
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I just gave this ago and realised that it doesn't work for FAR with capsules descending in reverse. So I can't adjust my reentry angle and get a good landing site because I'm at 180 degrees to what's being used for the descent model.

Yes, this issue has already been reported and is on the feature requests list. A work arround, and future updates about the feature implementation, can be found here : https://github.com/neuoy/KSPTrajectories/issues/10

Edit: didn't see Mandelbrot's answer before posting :-)

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I'm the author of the StageRecovery addon and this looks awesome! I have considered adding similar features to StageRecovery but it's always been too much work to do for me at the moment. If you ever decide to open up any of this as an API for other mods to use, I would love to be able to get the predicted lat/lon for landing and maybe the maximum velocity of a piece of debris/dropped stage. The lat/lon would be for determining the proper recovery value and the max velocity/speed would be for estimations of whether a vessel would be destroyed by Deadly Reentry (StageRecovery currently does this but since the atmosphere isn't actually changing the velocity, just gravity, the velocity at destruction is far too high).

Would it be possible to assume the orientation is the one with the least drag?

I'd also love to see this, or an extension of this, do aerobraking while on time warp.

Even if you can't do any of that, this is still awesome!

I could add an API for other mods to use (feature request added), but at this time the system is not designed to be used on multiple vessels at a time. Parachutes are not handled either. Also, it would work only for vessels that are fully simulated (not too far from the player), but the trajectory could be pre-computed at the moment a debris gets separated and kept in memory.

I'm not sure the orientation would matter that much. It will change the landing zone a lot, but who cares as the debris won't be actually simulated by the game anyway ? Any trajectory computed by the mod will look realistic enough if someone looks at it from the map view.

What I wonder is if it's possible to override KSP behavior of destroying debris entering atmosphere, and instead teleport the debris on the precomputed trajectory each frame to actually see them falling on the map ? At the end of the trajectory, they would need to be put on "landed" or "splashed" state so that they can be recovered later by the player (unless the impact is too strong and they get destroyed). I really don't know if KSP API would allow for this.

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What white messages do you get ? Is it better if you turn-off auto-update ? It may be that your craft has an unstable aerodynamic profile. What I mean by this is that the aerodynamic behavior would change a lot when the ship is deformed due to accelerations or other factors. If you turn auto-update off, the aerodynamic profile won't be refreshed automatically, so you'll have to click the "update now" button after stage separation for example. But at least it won't update each frame as I suspect is happening to you.

I had already thought of that at the time of the lag, it didn't help. I turned off the auto update and the lag persisted.

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I could add an API for other mods to use (feature request added), but at this time the system is not designed to be used on multiple vessels at a time. Parachutes are not handled either. Also, it would work only for vessels that are fully simulated (not too far from the player), but the trajectory could be pre-computed at the moment a debris gets separated and kept in memory.

I'm not sure the orientation would matter that much. It will change the landing zone a lot, but who cares as the debris won't be actually simulated by the game anyway ? Any trajectory computed by the mod will look realistic enough if someone looks at it from the map view.

What I wonder is if it's possible to override KSP behavior of destroying debris entering atmosphere, and instead teleport the debris on the precomputed trajectory each frame to actually see them falling on the map ? At the end of the trajectory, they would need to be put on "landed" or "splashed" state so that they can be recovered later by the player (unless the impact is too strong and they get destroyed). I really don't know if KSP API would allow for this.

All I would need or want is to tell the API to compute a single trajectory for the vessel after it is staged, and from that I take the lat/lon predicted for determining the distance from KSC, which affects recovery return rates. Honestly, it doesn't make too much of a difference since it takes many kilometers to reduce the rate by 1% but if I can get more accurate results by tying into another mod then I'd like to do that. The trajectory doesn't need to be drawn, but it should be assumed to use the orientation with the least drag, if possible (since the landing zone is all I want access to, not just that it landed). I don't even need the full trajectory, just the latitude and longitude, which would keep memory footprint low.

Parachutes wouldn't matter too much unless they're already deployed since they deploy so low that it might make the difference of a few kilometers at most. If they're deployed really high up then you'd expect them to fall faster than they would, but otherwise they'd fall straight down. Probably only a few kilometers different there as well, the error being from Kerbin rotating less than it should(so it'd "land" East of where it would if it was followed)

Conceivably it would be possible to do that (override the KSP behavior), but it wouldn't be easy. It would be simpler to draw the trajectory and some symbol on it even after the vessel is destroyed, but keep the vessel in memory to then spawn on the surface. You'd have to stop drawing the vessel as soon as it hits atmosphere though (it's not destroyed until about 22km) since the trajectory provided by KSP doesn't account for air resistance (obviously).

That'd be too much for me, personally, as semi-realistic landing zones are more of a novelty for a stage recovery mod than a requirement. If you really wanted to tackle that and add stage recovery features into this, that would be an awesome way of doing it though.

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The reverse descent issue is known and they are planning a fix for 1.0, just so you know. It works, apparently, but you have to attach a probe-core backwards and control from there.

This explains why it weirded out and didn't show a very accurate decent profile for my pod lol.

Well I downloaded it last night and was very excited for it and here is what I think.... It's AWESOME!!! I have been wanting this for ages, great job!!! I love both the atmospheric prediction and the landing location prediction for bodies without an atmo, I am eagerly awaiting the next update and the fix for the reverse entry thing in FAR.

Keep up the good work, this now has a spot on my must have mod list.

Cheers

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Been having some fun with this. Reverted to stock for the time being.

However, the game begins to chug when the active craft is destroyed (by ploughing it into the ground). Lots of frames dropped until you leave the scene.

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I had already thought of that at the time of the lag, it didn't help. I turned off the auto update and the lag persisted.

You said in a previous post it happened also when you are in orbit, do you mean the whole trajectory is above the atmosphere and you sitll have performance issues ? The mod should do nothing in this state. Another test you could do is download version 0.2.0, which disables prediction completely when you're not on the map view (unless you've set a target impact point). If you still have performance issues in this situation, I would tend to think it's not related to Trajectories. Also, it could help to know if your output_log.txt contains a lot of errors ; writing errors can slow down the game when it happens each frame.

Anyway, I've added an optimization task, that would never hurt, but I don't know when I'll have time.

Edited by Youen
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