Youen

[old thread] Trajectories : atmospheric predictions

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So, using FAR and a blunt body reentry, I find my trajectory is wildly off.

My actual landing site is in the mountains west of KSC when I aimed for the ocean east of KSC

Quick question: did you select the appropriate reentry posture (probably retrograde) in the Trajectories menu?

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Quick question: did you select the appropriate reentry posture (probably retrograde) in the Trajectories menu?

Hadn't messed with any settings, so that may be it

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So, using FAR and a blunt body reentry, I find my trajectory is wildly off.

My actual landing site is in the mountains west of KSC when I aimed for the ocean east of KSC

If you are having trouble I did a video on the basics of Trajectories here https://youtu.be/QzEDq_rgvlM it might be helpful.

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So, using FAR and a blunt body reentry, I find my trajectory is wildly off.

My actual landing site is in the mountains west of KSC when I aimed for the ocean east of KSC

Did you stage after you viewed the reentry calculation?

Did you check that Trajectories was set to use a retrograde reentry if you were reentering with a retrograde position?

Did you have any wings on your craft?

Did you use any airbrakes on your craft?

Are you using the latest FAR and Trajectories?

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Did you stage after you viewed the reentry calculation?

This is also affecting me - I set the target landing, burn my engines then stage to remove the fuel tank leaving me with just a pod and the landing position changes massively. Is there any way around this?

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This is also affecting me - I set the target landing, burn my engines then stage to remove the fuel tank leaving me with just a pod and the landing position changes massively. Is there any way around this?

You likely dumped a lot of mass. The calculation is going to be based of the vessel's current mass, so dumping the stage would lighten you considerably, leaving you to slow down more easily. I likely don't see a way to mess with this unless the mod gets coded 'lock out' stages above a certain number. (Say, set stage 0 or 1, and it looks only at those).

As a work around, perhaps you should design a deorbit stage into your vehicle. A small extra fuel tank with a tiny amount of fuel. Use your normal stage to get into a low orbit and circularize. Then de-orbit, blow the stage, and use the 'final' stage to make a correction burn, then dump it.

Also, be aware of how much ejection force a decoupler has. A big kick from a hefty decoupler can be the same as a short burn. Especially if the stage is heavy, and your pod is light and just jettisoned the stage BACKWARDS.

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How come it's not showing my trajectory after my aerobrake?

xab9auC.png

Edited by SmashingKirby148
I forgot to add a picture. ._.'

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It works with stock aerodynamics (although stock wings are not simulated) and FAR

Does this mean that the trajectory for a winged spaceplane in FAR will be accurately simulated?

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baldamundo: so long as you tell Trajectories the AoA you will use and you stick to that AoA.

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Suggestion:

RPM integration would be great, to have the trajectory projected on a screen. Something like a graph on the bottom and the trajectory above.

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Nice, been looking for something to assist me with my SSTO landings - hoping this will do the trick!

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Hey there!

This is a very useful and easy to use mod, and I have a request for it: that there was a way for me to predict the atmospheric trajectory of, say, stage 0, so I can plan my landings before I ditch the lower stages. Feasible?

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Could you add time-to-point when hovering over different parts of the white and red trajectories? Would be nice for planning a RemoteTech EDL schedule.

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This mod had honestly been one of the most helpful I have ever had, rivaled only by Kerbal Alarm Clock.

Now, I was looking at the promotional pictures and I noticed that the mod can predict landings on Non-Atmospheric bodies.

This doesn't happen on my computer. Is there a setting I need to change?

Thank you!

DMSP

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Now, I was looking at the promotional pictures and I noticed that the mod can predict landings on Non-Atmospheric bodies.

Check "Body Fixed Mode" in the options. Your trajectory will no longer be relative to actual space, but instead relative to the world you're orbiting. In other words, your trajectory will compensate for the planet's rotation.

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Youen, great mod! Might I kindly suggest implementing numeric information on landing zone? Like, the longitude and latitude of calculated impact spot. Or, instead, a distance from the target (like, "2km overshoot, 1km nominal"). Right now, it is sometimes hard to judge from map view, especially when one aims for landing accuracy under 100 meters or less.

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How does this compares to the trajectory estimates in Mechjeb who is pretty inaccurate to say it mildly.

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I use FAR, and it is extremely accurate if my ship can hold the designated facing. I regularly land ships from orbit to within a couple km of KSC using it, as long as they maintain stability at retrograde and I remember to set the trajectory to retrograde before doing my burn.

I don't know how good it is with stock, or spaceplanes.

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Youen, I'm not sure what I'm doing wrong here, but if I enter target coordinates for a specific spot on Duna (0N 100W), and then burn retrograde until landing prediction is very close to these coordinates, the round dot on the Navball is completely way off, as if I were on wrong trajectory. If I use "set current impact", which is close to 0N 100W, the dot is in the right place, but not of I enter coordinates manually.

I write 0, 100 in the field. Is my coordinate format wrong, maybe?

If you or anyone else could help me out, it would be great.

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Maybe there is a bug, I haven't used that functionality a lot. Can you see the green cross correctly placed after entering the coordinates ? Or only if you use "set current impact". There is still the bug where the green cross is hidden under the ground so I hope you can see it in your case.

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Maybe there is a bug, I haven't used that functionality a lot. Can you see the green cross correctly placed after entering the coordinates ? Or only if you use "set current impact". There is still the bug where the green cross is hidden under the ground so I hope you can see it in your case.

If I enter coordinates manually, I do not see green cross at all. I know it is sometimes hidden, but zooming out usually makes it visible. Not in this case. It is visible only if I do "set current impact".

If you have problems with fixing green cross visibility, I'd like to suggest that there could be a numerical output of distance between crosses. Like "impact 2km over, 1km nominal of target site". That would be a huge help when executing precision landings.

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