[FAR] How do I land accurately on a body with an atmosphere?

[peachoftree]

I am considering building a base on duna, but the one lingering concern I have is that landing all the modules in one place will be really hard. I use FAR and the trajectories mod has always been buggy for me (does not give a very accurate impact)

[Starhawk]

This is difficult with heatshield/parachute craft. That's why I like spaceplanes so much.

For non-spaceplane craft, Mechjeb can calculate atmospheric drag and predict a landing site fairly accurately, at least in stock. Not sure about FAR.

Good luck and happy landings!

[Kryxal]

Assuming you use KER or MechJeb, why not just establish a standard deorbit burn? From a known orbit (say 60 km circular), burning maybe 50 m/s retrograde at a known point should do the trick with a fair bit of precision given a good TWR.

[jarmund]

Assuming you use KER or MechJeb, why not just establish a standard deorbit burn? From a known orbit (say 60 km circular), burning maybe 50 m/s retrograde at a known point should do the trick with a fair bit of precision given a good TWR.

This won't work with FAR, as the modules are likely to be of diferent sizes and shapes, thus getting very different aerodynamic characteristics.

However, it should be mentioned that Dunas atmosphere is so thin that of all the planets, Duna will make the least difference. Having said that, make sure you have plenty of chutes, in addition to some retro-rockets to slow down your decent.

[eurybaric]

Assuming you use KER or MechJeb, why not just establish a standard deorbit burn? From a known orbit (say 60 km circular), burning maybe 50 m/s retrograde at a known point should do the trick with a fair bit of precision given a good TWR.

I kind of have the same prob as OP. So you mean as in to try a retrograde burn of some specified parameters and see where that gets? maybe we could then adjust the burn point on the orbit to suit our landing target? But then again, when you're transferring from Kerbin, you rarely end up in the same encounter orbit! So..... ?

Cheers!!

[Wanderfound]

Put some control authority on your craft and fly it there. Especially in a thin atmosphere like Duna, you can glide halfway around the planet without expending any fuel so long as you have a bit of lift.

This is easiest in a spaceplane, but also works with other craft. Even a bare capsule can substantially alter its descent trajectory just by tweaking the angle at which it's meeting the wind.

[jarmund]

Put some control authority on your craft and fly it there. Especially in a thin atmosphere like Duna, you can glide halfway around the planet without expending any fuel so long as you have a bit of lift.

This is easiest in a spaceplane, but also works with other craft. Even a bare capsule can substantially alter its descent trajectory just by tweaking the angle at which it's meeting the wind.

My TAC supply ship for Duna is mostly just a stack of TAC parts with a decoupler in each end connecting to fuselage, probe core, some very basic wings for stability, and control surfaces. Works like a charm. When I'm low and above the landing site i go for a stall to slow down, decouple and trigger the chutes. This was my backup solution after realizing that i couldn't estimate a landing spot if my life depended on it.

[Van Disaster]

Trajectories mod with the FAR compatibility does a reasonable job of predicting where you're going to land. I generally don't land in atmospheres without wings ( or the odd time I do I don't care where I land ) so I don't know how it handles parachutes, but you can probably make a good guess.

[peachoftree]

Thanks for all these suggestions! I have An idea of what i'm going to do now (pics to come)

[impyre]

My TAC supply ship for Duna is mostly just a stack of TAC parts with a decoupler in each end connecting to fuselage, probe core, some very basic wings for stability, and control surfaces. Works like a charm. When I'm low and above the landing site i go for a stall to slow down, decouple and trigger the chutes. This was my backup solution after realizing that i couldn't estimate a landing spot if my life depended on it.

This is a really solid solution. Jeb approves of dropping things on purpose. A powered descent will give you the most control, you can treat it as if it had no atmosphere for most purposes... of course it will increase the fuel requirement though. I generally use drag and chutes to slow me down until I have a periapse beneath the surface, and then use engines for more control.

When I do rely on chutes, I use multiple chute stages for Duna. The first stage of chutes has *way* more drag than I need for landing, to help grab the thin upper atmosphere and slow my horizontal velocity. Once I have less horizontal velocity than vertical velocity, I cut the first stage chutes loose and deploy the second stage. The second stage provides less drag (to avoid ripping them off), but plenty to land safely. By timing when I activate each stage, I can usually put it down pretty close to where I'm aiming. RCS or small engines can help adjust beyond that point if necessary.