How to land a booster on a drone ship?

[Atlessa]

So I have a Falcon-style booster, with enough hardware and fuel to softly land it on water, I have FMRS, and I have an OCISLY-styled ship in the general vicinity of where my booster usually splashes down.

Big question is: How do I stick the landing?

Manually, I feel, is virtually impossible, but even Mechjeb's "Landing guidance" feature seems to consider my target marker as a mere suggestion and doesn't mind coming down several Km off of that, and I don't have the know-how to effectively use KOS.

 

Any ideas?

[Dafni]

I can do it manually, sometimes, it just took me a lot of practice. It was my main goal in KSP for almost two years.

At first I used the mods Trajectories (for more accurate trajectory projections in atmo) and the mod Navhud (for having the prograde marker on the screen) but nowadays I can do it in stock. When I do attempt it these days the failure rate is still very high, but the successes feel very very rewarding.

I never bothered with FMRS (it's that time jump mod, right?) just generous use of quicksaves on my practice runs. And clever and quick switching between the craft. Apoapsis of the booster needs to be above atmo at stage sep in my case.

I first saw it done in all stock in the stream of EJ_SA and basically started doing it his way until I knew what to look for. Now I use the reentry burn for a midcourse correction and do the rest with the gridfins/bodylift. Only works if you are coming down almost on point before the burn though.

For me the landing takes place when the 2nd stage is ghost-riding to orbit, and after the landing I have to switch to it immediately for the circularization.

In my main play-through I hardly ever use barge landings anymore. Only use my Falcon9 when a RTLS is feasible. I can land it safe on the KSC peninsula >90% of the time now. Aiming for the launchpad if I feel adventurous. Haven't really bothered with the barge in a long time. Sometimes I go for Booster Island, that little island a bit north of the perfect equatorial launch azimuth.

You could look up some clips of EJ_SA on twitch to see how he does it. It helped me a great deal. That was back in the days of the first successful SpaceX barge landings.

Good luck and make sure to report back!

 

Edit: just thought of something. You say you can land your boosters softly on the water. What you have to do now is optimize that trajectory until you feel it is perfect, so you can splash down your boosters at roughly the same spot consistently. Use landmarks etc. Keep an eye on all the numbers, always stage sep at the same time and all that.

Once a booster is swimming in the ideal area use this as a target. Dont recover the boosters. Do it over and over and you will see the spread of your splashed boosters will tighten up over time, then put your barge at exactly the center of your now established splash site and you should be golden. I know it takes a lot of time and effort but it will be very rewarding once you nail it.

Edited February 20, 2020 by Dafni

[Atlessa]

I'm a little surprised... no one else who has any input on the matter?  No mods I overlooked, no checkbox in MJ I forgot to check (to ensure strict targetting, maybe), nothing?

Can't believe me and Dafni are the only ones who've tried this?

[Stone Blue]

11 minutes ago, Atlessa said:

Can't believe me and Dafni are the only ones who've tried this?

Mebbe try reading thru the Tundra Explorations thread, to see how peeps do it with that mod? or the couple threads for the modded drone ships... I know one was authored by spacepanda, and I think the other was Kartoffelkuchen ... vOv

[The Aziz]

Trajectories + KER landing marker. I've managed to land not more than few hundred meters from the lanchpad I was trying to aim for. Try to use as many guides as possible - Trajectories can show your path in flight even, not only in map mode. Try to aim a bit further than where you want to land (assuming you're not too far away to the sides but that you should figure out as soon as possible after separation) because you're gonna burn to land anyway, and that's gonna change your horizontal velocity too. And well, have a lot of control, rcs etc.

[CBase]

I did try a lot with a fork of Trajectories and Mechjeb to land at KSC runway. With few tries and fiddling with some parameters depending on the rocket, I get enough precission to actually hit my intended target +- 200m.

However I start from Orbit and can use a savegame to adjust. You want to start from launchpad and hit a target that is only few times bigger than a rocket. This increases your task to get repeatable.

My suggestion: get kOS and fully automate the flight. Then note the position where you are landing and place your drone ship there. Now use trajectories to fine tune the very final approach. It will be still hard work.