How to know the Landing position on Kerbin?

[SwissSpace93]

When i fly Life Support and Crew Changes to the KSS (Kerbal Space Station), i use for the reentry the trajectories mod it shows me the position where i land.

but when i set this up the maneuver node is i.e. in 40mins, kerbin rotates arround and then the position of Trajectories is at the same place but the surface has „traveled“.

the Real chutes deploys are set to 9000m drogue and 3000m for the Main chute.

when i land in the sea (1. trajectory from planned maneuver) i now land on the ground, when there is a high mountain the Parachutes will deploy to late and the Rocket crashes into the mountain.

 

is there any mod or how do you calculate the rotation of Kerbin to the trajectory?

[4x4cheesecake]

Usually, I would say "try and error" but while thinking about, it shouldn't be that hard to figure out.

A Kerbin day is ~6 hours, respectively 360 min long, so Kerbin rotates 360° in 360 min or 1° in 1 min. If you have a maneuvernode 40min ahead, kerbin will rotate ~40°, so you can draw an imaginary line from your maneuver node to the center of Kerbin and then 40° ahead back to your actual trajectory. The place where the second line crosses the surface of Kerbin, is roughly the position you should aim for with the trajectories mod. But keep in mind, that you have to move your maneuvernode which will be then more than 40min ahead, so your target marker will be again a little bit off. You can repeat this over and over again and your target marker should become more and more accurate (but the marker itself is already just an approximation).

I haven't done this before, just a quick thought and maybe just wrong

edit: becomes more complicated after thinking about it a bit longer...my first idea implies, that you are in LKO but if you are on the way back from another body and perform a mid-course maneuver (or just HKO), you have to calculate the time until you are entering the atmosphere and approximate the position again...

Edited May 18, 2018 by 4x4cheesecake

[RizzoTheRat]

If you make a node near the impact you can see how long to impact and then use the above to determine how far Kerbin will rotate in that time 

[SwissSpace93]

This sounds good, i need to try it.

but first i need a better Rocket for the KSS flights

[StrandedonEarth]

The Trajectories mod also draws a red X on the ground at the spot you'll land/impact. This spot is fixed to the ground and will not be under the end of your trajectory until just before impact, so you'll have to move your view around to find it.

[Superfluous J]

You can also set Trajectories to "Body Fixed Mode" that will show the trajectory your ship will take relative to the surface of the planet. Makes for some pretty (and pretty confusing) lines sometimes but accurately shows you where you'll be. I use it all the time to do "get a temperature reading over this spot on the Mun" contracts.

 

[Boersgard]

I had a learning experience yesterday with landing, albeit on the mun; not kerbin.

Jeb unfortunately got himself stuck on the mun without enough fuel to get back (my own fault, I figured I had enough fuel to do an orbital rendezvous with a satellite to get some samples before landing), so I sent a rescue mission. Naturally by the time I reached the mun to rescue jeb, his landing zone had moved into complete darkness. Perfect. In the sarcastic sense.

First thing I did was set Jeb's Munar 1 as my target, then got my inclination correct, then began burning retrograde - first to lower my circular orbit to ~15-20km, then when I was nearly overhead of him; as I found doing a burn too early/slowly tends to give you a lot of horizontal velocity - kill the horizontal velocity first, then worry about the vertical. Having a high TWR helps with this immensely. Additionally, I made sure to overshoot a little bit so I had more room/time for error. Once I was more-or-less falling directly towards/over jeb, and completely blind as a bat - I couldn't see any terrain at all, just a black mess - I turned to my navball and the (true height) altimeter/horizontal/vertical readouts from kerbal engineer.

I knew burning retrograde would slow me down and make my descent steeper, but I wanted to do course corrections to get closer to my target, which required a bit of trial and error to figure out, but essentially: Wherever you burn around the retrograde marker, you will push that marker directly away from your indicator - the further you turn before applying thrust, the faster you'll move the retrograde marker around. Then, I simply used this technique to push the retrograde marker towards my target - Munar 1. Additionally, I set my SAS/RCS to radial-out. This meant that after any course corrections I made, the lander would auto-correct to facing directly away from the mun - it was VERY handy to keep my orientation considering I couldn't see anything. If I flipped the wrong way (I went upside down a couple times), I just let go and the autopilot put me up the right way. Strong RCS/SAS is critical!

I occasionally flipped to retrograde on the autopilot to help cancel out extra horizontal velocity, but for the most part radial-out was the best choice. Eventually I reached a point where I was coasting along at about -5-10m/s vertical, and ~30-50m/s horizontal, and just sort of glided towards my target. When I finally made landing, I wound up only about 350m away. Not bad for my first time landing anything in pitch darkness relying only on instruments imo.

Anyways, I got out, dropped a micro-rover, discovered it couldn't actually move, and then RCS-hopped valentine over to jeb's lander. Unfortunately it turned out he died and Munar 1 was scattered all over the landing area. Which I guess was from the life support mods and him losing electricity when the sun went under the horizon. RIP.

Also my rescue mission used up too much fuel landing and needed a rescue mission.

 

Quick album of the screenshots I took: https://imgur.com/a/7nc8nxN

Edited May 19, 2018 by Boersgard