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[old thread] Trajectories : atmospheric predictions


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I can confirm that after this mod was installed, "Infinite Fuel" was ON even though I never set it. I turned it off at the debug menu.

OK, that was my fault. I shipped a debug DLL, instead of the release one. I have some debug code that enables infinite fuel automatically for my tests.

Really sorry about that, I've uploaded the correct DLL on GitHub (the previous one is overriden).

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This looks great! Can't wait to try it.

Afraid I have a bit of technical business to transact though--can you add a note to the OP about your license? The repo says MIT, but by the rules that should be in the opening post too.

Thanks for pointing that out, I have updated the first post accordingly.

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...wow. I can't try it right away, but if there are no major bugs this is the best thing in a while :)

I have indicated on the first post that bugs are to be expected... If you want something clean, you'll have to wait a little more. Can't harm to try, though.

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I'm using FAR.

I did a quick fly-by of the Mun and burned to escape to a 20km Pe at Kerbin for reentry. After leaving Mun SOI I decided to EVA because I wanted to pull some Science data from a pair of Materials Study and Mystery Goo containers into the Command Pod (the stock Mk1 1.25m). After exiting the (very small) spacecraft the clock numbers went from green to yellow and my FPS plummeted. I assumed this was because AT was calculating my decent profile so I reentered the spacecraft, went into Map mode, and unchecked the two boxes (Display Trajectory and Auto-update iirc?) in the upper left corner. This did not help when I EVA'd again. I boarded the craft again and burned a little radial out to raise my Pe out of Kerbin's atmosphere and that did the trick. I was able to EVA with good FPS and retrieve the Science data.

I have not been having good luck with even landing in the right ocean with a Command Pod, I think I may know why now that I think about it. I'll do another flight and come back with an update.

EDIT: After looking at the Page 1 screenshots again, I realized Youen's example flight is done with a space-plane, which obviously does not reenter backwards like a pod does. I attempted setting all the AoA sliders to 180 degrees, because my nose is going to be pointing at the retrograde vector throughout the descent. Discovery: they only go up to 30 degrees. The next thing I tried was putting a probe core upside-down on top of my pod and controlling the vessel from there when planning reentry. Long story short: the predicted LZ was extremely accurate.

I'd like to suggest some sort of functionality for including pods for Atmospheric Trajectory so this workaround isn't necessary. Thanks for the awesome plugin, btw.

lwg7X3tl.jpg

Edited by Carter
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Query - since this tool works with FAR, does it also work with NEAR? I've used FAR in the past (and I'm an aerospace engineer by education) but I never liked fiddling with all of FAR's GUI elements; NEAR is thus perfect for me - as if ferram read my mind when he created it. So I'm using NEAR in my current build and loving it. I really hope this new mod works with NEAR the same way it does with FAR.

Based on what I read from the dev (unless names need to change and such to make it compatible), I'd say that it should indeed work with NEAR, as the FAR and NEAR plugins don't seem to be too different. I've never looked at the code so I'd have no clue (and would still have no clue if I looked at it), but I believe they are very similar.

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EDIT: After looking at the Page 1 screenshots again, I realized Youen's example flight is done with a space-plane, which obviously does not reenter backwards like a pod does. I attempted setting all the AoA sliders to 180 degrees, because my nose is going to be pointing at the retrograde vector throughout the descent. Discovery: they only go up to 30 degrees. The next thing I tried was putting a probe core upside-down on top of my pod and controlling the vessel from there when planning reentry. Long story short: the predicted LZ was extremely accurate.

I'd like to suggest some sort of functionality for including pods for Atmospheric Trajectory so this workaround isn't necessary. Thanks for the awesome plugin, btw.

http://i.imgur.com/lwg7X3tl.jpg

What about a checkbox/toggle that changes the AoA sliders between prograde and retrograde so that things that fly in rear end first can still take advantage of what aerodynamics they have for their reentry profile.

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What about a checkbox/toggle that changes the AoA sliders between prograde and retrograde so that things that fly in rear end first can still take advantage of what aerodynamics they have for their reentry profile.

When I made that comment I assumed command parts are sorted between probe cores, pods, and cockpits, but now that I think about it that is probably not the case. A Nose to Pro/Nose to Retro toggle sounds like a good idea. If my original assumption is correct, however, I still think BFGfreak's proposal is superior to what I had in mind, as it wouldn't interfere with creative uses of pods and cockpits you may find among our more imaginative builders. I was thinking of having pods' reentry calculated with their noses to retrograde by default, if that is possible.

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This looks great! Can't wait to try it.

Afraid I have a bit of technical business to transact though--can you add a note to the OP about your license? The repo says MIT, but by the rules that should be in the opening post too.

And in the download itself. I got bit by that one recently.

(oops... forgive please for the double posting...)

Edited by Starwaster
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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.

It's incredibly likely that it will work 'out of the box' right here and now.

SDF doesn't do anything unusual except modify the maximum_drag field to nullify the drag caused by resource mass.. Any calculation you do for stock drag will work for SDF.

Stock drag also has two unused drag models and in the future I might do something with those, but that wouldn't require any more attention on your part than for FAR. (less actually)

That was a motivating factor for SDF, that it be compatible with everything designed with stock drag in mind.

Edited by Starwaster
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example flight is done with a space-plane, which obviously does not reenter backwards like a pod does.

Good point here. I'm adding that to the feature requests on git hub. Also, your performance issues (lag + red trajectory disappears) might have been related to a recent bug I fixed, a new version is available on git hub.

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It's incredibly likely that it will work 'out of the box' right here and now.

SDF doesn't do anything unusual except modify the maximum_drag field to nullify the drag caused by resource mass..

OK, didn't know that. It should work, indeed, but I haven't tested.

- - - Updated - - -

Suggest Toolbar (Stock or Blizzy's) integration.

That's done in the latest release :-)

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I noticed it doesn't work with the stock drag model, KSP.log just fills up with NREs because it's trying to access FARs DLL. Being able to hide the windows would be good too.

I was working so much on the FAR part that I might have forgotten to re-test without FAR. It used to work but I might have broken that. I'll double check tomorrow.

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This plugin is amazing; it has so many things that I've always wanted (and that I wrote a python script for). You're a god among modders.

One suggestion that would boost the awesomeness even more, IMHO: add a toggle to plot the white/red trajectory in the body-fixed ("surface") system. That way, it wouldn't match up with the stock orbit, but instead with the impact marker (eggrobin's Principia has this plot mod, Example).

Possible applications:

  • If you're in a low, but not intersecting, trajectory over an airless body, it will show the correct position of the periapsis.
  • (unrelated to atmospheres/landing) imagine the plot for kerbostationary satellites...
  • Finally, slightly useful trajectory predictions for airplanes

Edit: Looking at the code, you'll want to rename Trajectory.PredictImpactPosition to something like CalculateRotatedPosition and use that function on every data point in InitMeshFromOrbit and InitMeshFromTrajectory.

Edited by mic_e
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This plugin is amazing; it has so many things that I've always wanted (and that I wrote a python script for). You're a god among modders.

One suggestion that would boost the awesomeness even more, IMHO: add a toggle to plot the white/red trajectory in the body-fixed ("surface") system. That way, it wouldn't match up with the stock orbit, but instead with the impact marker (eggrobin's Principia has this plot mod, Example).

Possible applications:

  • If you're in a low, but not intersecting, trajectory over an airless body, it will show the correct position of the periapsis.
  • (unrelated to atmospheres/landing) imagine the plot for kerbostationary satellites...
  • Finally, slightly useful trajectory predictions for airplanes

Edit: Looking at the code, you'll want to rename Trajectory.PredictImpactPosition to something like CalculateRotatedPosition and use that function on every data point in InitMeshFromOrbit and InitMeshFromTrajectory.

Good idea indeed, I'll consider that when the main functionalities are stable and usable (including NEAR etc.). Or tell me if you want to contribute that part of the mod (as you have already looked at the code)

Thanks for the suggestion.

I never heard of Principia until now, which seems an interesting mod, I'll follow the development. But as I understand it isn't usable yet. I can't tell if N-body simulation could make KSP more interesting, or if it would actually make it less fun. Depends on each one taste I guess.

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