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About Youen

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    Spacecraft Engineer
  1. Hi, Does anyone know if there is a combination of mods that would allow playing with RSS and clouds with KSP 1.2.2 ? It doesn't seem environmental visual enhancements is compatible with RSS, and I can't find a recent version of RVE that would work with KSP 1.2.2. I'd appreciate any pointer if such a thing is at all possible. Thanks.
  2. This is normal if your ship has steering fins: when you change attitude, they move, which changes the drag of the ship. Not sure that's the explanation, but maybe it is. If you have different results depending on your ship attitude, even when it is static (not steering, not rotating), then it's something else.
  3. I'm not sure it's an issue, when you use RK4 integration you do not feed it with different accelerations for each 0.04s time step. The force varies very slowly, that's also the assumption used for the cache system. To be more precise, you could adjust the force depending on velocity, by assuming it varies with squared velocity (that would still be faster than going through the whole force computation stuff). I think it would make sense to only give accurate predictions for 1x time warp. Or maybe a prediction somewhere in between. Or ultimately give players the option to choose which one they want, but that's a bit far fetched... Also I'm not sure if using 4x warp means KSP time steps are multiplied by 4, or if it depends on the computer CPU power. In any case, if even the KSP simulation can't be reproduced with high precision, it won't be possible to predict it with a greater precision... I also remember that at some point I made tests and noticed that saving/loading could change the landing spot.
  4. Not necessarily. If I remember correctly the default KSP timestep is 0.04 (you can see it in the game settings). If you just use the same acceleration multiple times (we are trying to solve integrator accuracy, but not to increase force computation frequency), it should be fine, as it's just a bunch of multiplications and additions (you would have about 10 "sub-steps" for each simulation step? That means 20 additions and 10 multiplications). You can even pre-compute acceleration*time_step. I can't guarantee without testing, but I don't think it will have a big impact on performances.
  5. I think it's just the most naive thing you can do: velocity = velocity + acceleration * time_step position = position + velocity * time_step
  6. Do you get the same result as with the previous integrator? That could mean either you did not implement it right (but I don't think so, chances are you would get completely wrong results in that case), or more likely it just proves that precision issues do not come from the integrator, or, even worse, that getting more "precise" results will diverge more from what KSP does. Because KSP does naive integration (with a small time step, but that might only increase numerical errors). That's just a quick thought, maybe I'm wrong Maybe integrating with the same time step as KSP would make it better? For performances, you could use the same force in multiple integration iterations (assuming it wouldn't vary too much over a short time). And then try with a naive integrator instead of Verlet.
  7. Thanks for taking over @Kobymaru, and thanks and good luck to all contributors currently working on the mod.
  8. This thread has moved here: Please only respond in the new thread. Thanks.
  9. You have accuracy issues with KSP 1.0.5 and Trajectories v1.4.5 ? That's weird, because the changelog says accuracy issues with stock aerodynamics were fixed in that release, so it should mean I had actually validated it was accurate after the fix.
  10. That's a bit of an overstatement... Unless you mean my code is so awful that no one can understand it ;-) Unfortunately, I've lost interest in KSP in general for quite some time now, and I don't really want to reinstall the latest version just to fix bugs and upgrade code for the latest version, which is precisely the part I dislike about modding. Maybe I'll get back to it later, but no ETA nor promises. In the meantime, I can at least update the opening post inform people of what works or not, and on which version of the game. I think the most problematic issue is that prediction is not accurate, but I don't know what is the last version of KSP for which it worked correctly? Also, despite what @Kobymaru says, I'm sure there are a lot of people around here that are able to improve the mod (starting with himself). And I'd be happy to release the work of anyone who would like to fix the issues / improve the mod. I can also give direct access to spacedock and AVC, and I think moderators can transfer the opening post ownership, or failing that we could create a new thread, if someone wants to maintain the mod. I'm really sorry to "let down" the current users of the mod, but fixing this kind of issue can be cumbersome, and I don't want to force myself to do it if I'm not even going to play the game after that.
  11. Module manager is used to inject a module in all command parts that will store your descent settings (angle of attack, etc.) so that you don't loose them when switching vessel or saving/loading a game. I have never tested the behavior without it, so you could expect issues. As a side note, I don't see why you would want to remove it ; it's just a tool to standardize how mods add or remove modules to parts, so that they remain compatible with each other (most of the time).
  12. You can't void Trajectories warranty (there is none).
  13. @Cdw2468 It's supposed to work and predict lift of your wings (you have a settings window to indicate how you intend to fly, either by setting the angle of attack (angle relatively to your velocity vector), or the angle above/under the horizon. Since you can adjust with a plane during your descent, it's usually possible to make it to the runway. Actually, the mod was designed exactly for this purpose (I couldn't land my shuttles without it), though it's useful for other kind of manoeuvers (aerobraking, etc.) However, recent player reports (read above) indicate that there are bugs with the latest version of the game/mod, and that the prediction does not work as expected. I haven't the time to look into this issue at the moment though I don't know why you say that ? Unless there is a bug, you should get a prediction as soon as you enter the SoI of the planet. So when you are orbiting Kerbin (for example), it should predict the trajectory with drag and lift. As stated above, however, it appears there is a bug with the current version of the mod and KSP. Thanks, my pleasure Even though I don't have time to work on the last reported bug :-/
  14. And also, IRL the planet is ten times bigger which means one should multiply in-game imprecision by ten before comparing with real life.
  15. 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.