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[old thread] Trajectories : atmospheric predictions

Youen

By Youen
in KSP1 Mod Releases

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Superfluous J

Superfluous J

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I'm kinda confused still on how to use this. I had hoped this would let me target something near the KSC and then give me guidance on where to burn for deorbit but I'm guessing that's more then it can do. EDIT: I'm on the x64 version.

It doesn't work with maneuver nodes so what you need to do is actually burn your ship so its trajectory intersects the atmosphere, and tweak it forward and back until the red X gets close to KSC.

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prophet_01

prophet_01

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I see my shuttle program making it's way to career mode *-* landing the same shuttle with different payload weights always screwed up my landing attempts. Once I actually managed to survive a vertical fall from 20 km above ksc and landing horizontal with only using a little propellant just before touchdown. I don't want to do that again though.

Thx for saving my kerbals from those horror trips that I call "landings"

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Czerky

Czerky

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I've been playing around with your code, and was thinking about a quick way to get reverse (i.e. pod re-entry) descent predictions with FAR. In this section where you separate the Reference Transform (vessel steering orientation) into vectors used for the FAR simulation:

Transform vesselTransform = vessel_.ReferenceTransform;

Vector3d vesselBackward = (Vector3d)(-vesselTransform.up.normalized);

Vector3d vesselForward = -vesselBackward;

Vector3d vesselUp = (Vector3d)(-vesselTransform.forward.normalized);

Vector3d vesselRight = Vector3d.Cross(vesselUp, vesselBackward).normalized;

Would it work if I just switch the forward and reverse vectors for the case of reverse descents? I set up code to do that via an extra GUI button and it seems to work for reverse descents (only tested for 0 AoA so far). I was basically just trying to emulate the backward probe core workaround that people are using.

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marce

marce

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Oh...My...God... What have you done? I always wanted this for my shuttles and the only way to kind of have this was with MJ (which I object to using for reasons). You have my respect. Also, well done on getting featured on 'modding mondays' on http://kerbaldevteam.tumblr.com/

Plus there is hope that sarbian can take the approach or interface with this to make MJ understand FAR atmo landings (better).

Nice work Youen! Maybe SQUAD will now take FAR and this and pull it into stock to rescue the poor stock-only guys :wink:

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DasValdez

DasValdez

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Your mod is awesome, and you should feel awesome. Did an entire stream tonight trying it out on twitch. It's going on the Academy must have mod list.

Here's a highlight of a rather accurate landing made possible by the mod. I also do a bit of explanation on how it works and how to use it. I plan to do an entire 2 hour Academy session this week highlighting this.

http://www.twitch.tv/dasvaldez/c/5170719

WELL. DONE. SIR. Hats off.

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INSULINt

INSULINt

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I have a bug where the trajectory is visible in vessel view and even though it is off I can see it in map view

http://imgur.com/a/HLcg3

This reminds me to inquire if you would be able to add the ball markers to navhud. I know an api is planned, and I have no idea if NavHud is customizable from the outside, and therefore no idea as to which side would have to add to the other.

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sarbian

sarbian

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Plus there is hope that sarbian can take the approach or interface with this to make MJ understand FAR atmo landings (better).

The problem is integration with MJ. I look into it more when things stabilize. I'm sure I'll find a way to work with a fellow Frenchman :)

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marce

marce

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How does this work with FAR/NEAR? Does it recalculate base on the way your craft is turned?

I thought that he would be calling the FAR API for several points which I assume should take the craft orientation in account, may be wrong though :rolleyes:

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Alshain

Alshain

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I thought that he would be calling the FAR API for several points which I assume should take the craft orientation in account, may be wrong though :rolleyes:

Well I asked because when he mentions planes it says it assumes your pointing at the velocity vector, but if you're bringing in a command pod and using DRE, the opposite is probably true since the heat shields are usually on the bottom, which would make this beyond inaccurate. I'm hoping it's just confusing documentation and the plugin is smarter than that.

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marce

marce

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Well I asked because when he mentions planes it says it assumes your pointing at the velocity vector, but if you're bringing in a command pod and using DRE, the opposite is probably true since the heat shields are usually on the bottom, which would make this beyond inaccurate. I'm hoping it's just confusing documentation and the plugin is smarter than that.

Oh! I missed that completely. Since I don't do planes I always enter butt (heatshield if in atmo) first...

I'll do a quick test if it makes any difference.

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Akira_R

Akira_R

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Well I asked because when he mentions planes it says it assumes your pointing at the velocity vector, but if you're bringing in a command pod and using DRE, the opposite is probably true since the heat shields are usually on the bottom, which would make this beyond inaccurate. I'm hoping it's just confusing documentation and the plugin is smarter than that.
Oh! I missed that completely. Since I don't do planes I always enter butt (heatshield if in atmo) first...

I'll do a quick test if it makes any difference.

So yes it works beautifully with FAR, unfortunately though it assumes your craft is oriented along the velocity vector, obviously the least ideal orientation for a pod, you can adjust the AoA it uses to calculate the drag in the UI in map mode, but it is unfortunately caped at 30 degrees for some reason, I know there was an issue logged on github and from what I understand this is something he is working on, for the time being the best workaround for this is to clip a probe core between your pod and heatshield facing backwards and then select that as your control point when you want to see your reentry profile. Otherwise you still have to guesstimate, and let me tell you it makes a ridiculously large difference between what it shows and where you will end up.

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Alshain

Alshain

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Posted (edited)
So yes it works beautifully with FAR, unfortunately though it assumes your craft is oriented along the velocity vector, obviously the least ideal orientation for a pod, you can adjust the AoA it uses to calculate the drag in the UI in map mode, but it is unfortunately caped at 30 degrees for some reason, I know there was an issue logged on github and from what I understand this is something he is working on, for the time being the best workaround for this is to clip a probe core between your pod and heatshield facing backwards and then select that as your control point when you want to see your reentry profile. Otherwise you still have to guesstimate, and let me tell you it makes a ridiculously large difference between what it shows and where you will end up.

Meh, that's not worth it. I'll install it for my planes and non-atmospheric landings just for the sake of beta testing but till that's fixed it isn't going to work for command pods in FAR. It's a very good start though, very promising.

Edited by Alshain
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Alshain

Alshain

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Well it occurs to me, with a command pod you would also have to predict when the chute will open and then calculate based on that chute. Then you would probably need to support the incredibly popular RealChute mod too. For that reason I'm not sure it would work with command pods entering an atmosphere in any way, stock, FAR, NEAR, whatever. So yeah, It's a very good start but it's geared to planes and moon landings right now. In time I'm betting new things like chute prediction and heat shields and such can be added.

Edited by Alshain
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