Landing & docking to a landed ship

[Kermanzooming]

Has anyone been able to land a craft so precisely so as to dock it to a landed one? I'm not talking about landing and then docking while on wheels, but having a landed craft and then landing another one just on top so they dock...

 

(Haven't looked but probably Scott Manley has done it )

[magnemoe]

On low gravity worlds like Minmus its not very hard to hover and land on an docking port with rcs.
If you talk about doing it on Kerbin and no vtol jet engines it would be hard. 

[Majorjim!]

Just now, Kermanzooming said:

Has anyone been able to land a craft so precisely so as to dock it to a landed one? I'm not talking about landing and then docking while on wheels, but having a landed craft and then landing another one just on top so they dock...

 

(Haven't looked but probably Scott Manley has done it )

You can see it happen for yourself in @katateochi's old but still EPIC modded constellation mission video here:

 Docking landing is at 27:50.

 Even Kat admitted it took a few attempts to get it right!

[Kermanzooming]

23 minutes ago, Majorjim said:

You can see it happen for yourself in @katateochi's old but still EPIC modded constellation mission

OMG! Thanks for adding another KSP video to my 'Have to watch this' list 

[Foxster]

I've done it - once, after a lot of F5/F9!

I'd planned for it to be my way for a re-fuel shuttle to collect fuel from a Minmus-based refinery. Definitely far too hard to have been worth it. 

[Kermanzooming]

8 minutes ago, Foxster said:

I'd planned for it to be my way for a re-fuel shuttle to collect fuel from a Minmus-based refinery. Definitely far too hard to have been worth it. 

That was also my plan, but I will have to find an alternative...

[Foxster]

An interesting alternative is to put a claw on the bottom of a craft and have it land on a large platform. After landing, lower the landing struts to engage the claw to the platform and Robert is your mother's brother!

[katateochi]

16 minutes ago, Majorjim said:

 Even Kat admitted it took a few attempts to get it right!

It actually took quite a bit of training! I spent ages doing practice runs on Mun to figure out how best to do it before the actual mission.  I used HE to put the practice craft in Mun orbit and saved, and then did the deorbit and landing attempts and reloaded it for another run.  Did that quite a few times (like actually several hours of practice runs!). It was like spending time in a simulator. 

The three key tricks to it are; 1) it's all about the navball, 2) find the level of throttle that allows for an almost perfect hover and modify your descent with RCS, 3) it's all about the navball! 
As soon as you can see the target craft, click on its docking port and set it as the target, get your craft pointing perfectly straight up (actually, if you note in the vid, I used MJ's SURF function to maintain a perfect pitch of 0). Then focus entirely on the navball and use RCS to get the target marker and your heading marker all perfectly lined up with the navball's crosshair.  If all three are inline then your're directly above it and not drifting sideways.  
Find the throttle balance that puts you in a near perfect hover, then you can make small adjustments to your decent with RCS (which is easier than controlling it with just the throttle).  but the longer you spend hovering the lighter your craft gets so you have to account for that. 

With practice you can get it pretty reliably and it's extremely satisfying! 

[polytechnique]

I managed to do it a while ago...

It takes a few tries. My initial strategy was just to land the top section nearby first, and then hover over and dock on top. I've never been able to do it directly, without landing nearby first...

 

[Kermanzooming]

2 hours ago, Foxster said:

An interesting alternative is to put a claw on the bottom of a craft and have it land on a large platform. After landing, lower the landing struts to engage the claw to the platform and Robert is your mother's brother!

Good idea, Claws are really underappreciated in my humble opinion. I have to practice my precision landings however, my closest landing to the target was 2 Km away...

[foamyesque]

Honestly, I'd just use the Klaw. Much simpler.

[Tyko]

Given how difficult and risky a docking landing is (without F5/F9 you're risking all your equipment and maybe lives) I'm just using KAS and its pipe connectors. You have a port on each vessel and a kerbal can create a pipe connection. Land near your mining rig, run a pipe between the two, transfer your fuel, disconnect the pipe.

It feels more "realistic" and your landing accuracy only has to be in meters rather than near-perfect.

 

[TotallyNotHuman]

2 hours ago, tjt said:

Given how difficult and risky a docking landing is (without F5/F9 you're risking all your equipment and maybe lives) I'm just using KAS and its pipe connectors. You have a port on each vessel and a kerbal can create a pipe connection. Land near your mining rig, run a pipe between the two, transfer your fuel, disconnect the pipe.

It feels more "realistic" and your landing accuracy only has to be in meters rather than near-perfect.

[image snipped]

I do agree, KAS is a godsend for those of us that can't land very precisely (admittedly, one still needs some level of precision for KAS pipes to work, what with its limited range), but there are two problems: First of all, setting up refueling pipes become impossible for uncrewed craft (e.g. a refueler) unless there are Kerbals present at the refueling base; second of all, using KAS has a chance to invoke the Kraken.

[Tyko]

9 minutes ago, TotallyNotHuman_ said:

I do agree, KAS is a godsend for those of us that can't land very precisely (admittedly, one still needs some level of precision for KAS pipes to work, what with its limited range), but there are two problems: First of all, setting up refueling pipes become impossible for uncrewed craft (e.g. a refueler) unless there are Kerbals present at the refueling base; second of all, using KAS has a chance to invoke the Kraken.

Avoid the Kraken by avoiding scene changes with pipes attached. Most Kraken attacks happen when physics is loading. I land my tanker, connect the pipe, do the fuel transfer and then disconnect the pipe all in one session. Doing this avoids having physics reload.

Edited August 2, 2016 by tjt

[Tourist]

I once docked a science module to a hitchiker module on the surface of minmus. The hitchhiker module was the hub of a base. The science module was maneuvered into place using a nuclear skycrane with tons of RCS. It was a massive pain. I'm pretty sure I've significantly worn down the F9 key because of it. However it was pretty satisfying when it eventually snapped into place. 

[Landge]

I used the 'land nearby then hop to dock' technique to attach my habitat modules to the central hub...

My frame rates tanked adding the third wing so I scrapped the idea of adding the forth, final wing.

 

[Curveball Anders]

19 hours ago, TotallyNotHuman_ said:

I do agree, KAS is a godsend for those of us that can't land very precisely (admittedly, one still needs some level of precision for KAS pipes to work, what with its limited range), but there are two problems: First of all, setting up refueling pipes become impossible for uncrewed craft (e.g. a refueler) unless there are Kerbals present at the refueling base; second of all, using KAS has a chance to invoke the Kraken.

I use DMagic's EVA Transfer (and struts) instead of the full KIS/KAS.

[Foxster]

I just had a go at landing on a platform with a Claw. 

Wasn't too hard. Landed from orbit about 200m away and then hopped over. 

If I was doing it again I'd put RCS on the refuel tug (oh and a docking port) so I could actually dock with a ship in orbit and refuel it .

Edited August 3, 2016 by Foxster

[Corona688]

On 8/2/2016 at 6:10 AM, Kermanzooming said:

Has anyone been able to land a craft so precisely so as to dock it to a landed one? I'm not talking about landing and then docking while on wheels, but having a landed craft and then landing another one just on top so they dock...

 

(Haven't looked but probably Scott Manley has done it )

I think I saw it done in the 'what did you do in KSP today' thread.  A bad landing left a mun lander or something with an intact pod with docking coupler atop, but no fuel or engine.  He landed a "thrust pack" of fuel tank and radial engines atop.

[Archgeek]

Knowing things about how docking ports do, I'd rather have a down-facing in-line or shielded port, with room underneath it, and a special service landing craft that has rover wheels which engage when the landing legs are pulled in, plus ports on little tabs stick out beyond the wheels and main body.  Manuever the port under the base's port, then hit the landing gear to raise the service port to meet it.  Wheels are pretty buggy right now, but I think that's aircraft wheels and not rover wheels.

[Corona688]

Nah, all wheels are bugged.  Not to the 'world is over' degree some say, but habits and designs may must change a bit to accommodate them.

[Tyko]

20 hours ago, Landge said:

I used the 'land nearby then hop to dock' technique to attach my habitat modules to the central hub...

My frame rates tanked adding the third wing so I scrapped the idea of adding the forth, final wing.

 

That's a very cool looking base! Took me a second to realize you'd built a "deck" on top for the whole thing. A deck like that deserves a hot tub and a BBQ grill

[Landge]

3 hours ago, tjt said:

That's a very cool looking base! Took me a second to realize you'd built a "deck" on top for the whole thing. A deck like that deserves a hot tub and a BBQ grill

Thanks! I like the idea of adding a hottub & bbq pit. I'll see if I can come up with something that passes. The deck's rails were made using strut connectors attached to qubic octagonal struts for posts. With no collision detection they are just there for looks.  

[magnemoe]

On 2.8.2016 at 11:13 PM, tjt said:

Avoid the Kraken by avoiding scene changes with pipes attached. Most Kraken attacks happen when physics is loading. I land my tanker, connect the pipe, do the fuel transfer and then disconnect the pipe all in one session. Doing this avoids having physics reload.

Have plenty of kas connected base segments, still in 1.13 I have far more problems than back before 1.0. Looks like main issue is landing legs shifting then you transfer fuel.
Solution is to disconnect everything before fueling up larger tankers. Also have disconnect kas winches as an standard key so if you get problem just press it to separate. 

 

[Hotel26]

17 hours ago, Archgeek said:

Knowing things about how docking ports do, I'd rather have a down-facing in-line or shielded port, with room underneath it, and a special service landing craft that has rover wheels which engage when the landing legs are pulled in, plus ports on little tabs stick out beyond the wheels and main body.  Manuever the port under the base's port, then hit the landing gear to raise the service port to meet it.  Wheels are pretty buggy right now, but I think that's aircraft wheels and not rover wheels.

Yup.  I've been using the following system that is standardized across lander, fuel rover, drill rigs and lunar flitter -- basically, anything that transfers fuel on the surface.

I considered ports on underbellies and lifting drill rigs on legs in order to service them underneath (like your idea) but I eventually decided it would all work better with side-mounted ports.  This is an old photo and the rover port drove in under the service port and then front legs lifted it up if necessary.  With the addition of the flitter, (pic 2), I had to refit the whole system for the fuel rover port to drive over the service port.

I do the initial design adjustments and testing near the pad at Kerbin Space Center.  When it's tuned correctly, you do not need the legs on the rover to mate -- you'll get capture magnetically just driving over.  If the terrain is uneven, the legs will save your bacon.  And if I *just* can't get it, the Docking Port Alignment Indicator finishes off the job.

 

 

Edited August 4, 2016 by Hotel26