How to land a Rover

[Paul G]

Running the following on MacOS:

• Kerbal 1.9.1.2788
• Making History 1.91
• Breaking Ground 1.41

I'm reasonably advanced in the Tech tree - I have unlocked the bits necessary to build a rover, but I'm struggling to come up with a reliable way of getting a rover to my destination.

My lander shown below, will land me on the Mun or Minimus, and allow me to leave the base of the lander behind (with a scientist), and return the science I collect back to Kerbin.

My rover is secured via a docking port, and whilst I can get to my final descent quite happily (politely ignoring the slight plume impingement on my rover if I manoeuvre the wrong way). I've tried slowing my descent to single figure ms at low heights <50m, or even landing and then undocking the rover, but the undocking is so energetic my rover is flung to the floor and explodes, or tips my lander over (on Minimus) if I release whilst landed.

There must be a more elegant way of getting a rover down safely., but I can't see how I would release it - should I be looking at using hinges to make doors/ramps to a space in my lander where the rover sits until I'm landed, or should I be building rovers as landers in their own right?

Thanks

Paul

 

[Regor]

11 hours ago, Paul G said:

Running the following on MacOS:

• Kerbal 1.9.1.2788
• Making History 1.91
• Breaking Ground 1.41

I'm reasonably advanced in the Tech tree - I have unlocked the bits necessary to build a rover, but I'm struggling to come up with a reliable way of getting a rover to my destination.

My lander shown below, will land me on the Mun or Minimus, and allow me to leave the base of the lander behind (with a scientist), and return the science I collect back to Kerbin.

My rover is secured via a docking port, and whilst I can get to my final descent quite happily (politely ignoring the slight plume impingement on my rover if I manoeuvre the wrong way). I've tried slowing my descent to single figure ms at low heights <50m, or even landing and then undocking the rover, but the undocking is so energetic my rover is flung to the floor and explodes, or tips my lander over (on Minimus) if I release whilst landed.

There must be a more elegant way of getting a rover down safely., but I can't see how I would release it - should I be looking at using hinges to make doors/ramps to a space in my lander where the rover sits until I'm landed, or should I be building rovers as landers in their own right?

Thanks

Paul

 

It would be much easier if the rover was landed separately. You could use a small sky crane with ant engines to land it then. 

As for landing it with your lander, you could use a stack decoupler if you are fine leaving it there, with ejection force set to the lowest.
 

The last thing you could do if you want to land it with a lander and return it is hover your lander a few meters above the ground of the celestial body, and undocking it in midair. This will reduce the effect of the bouncing.

Edited April 7, 2020 by mabdi36

[Rocket Witch]

7 hours ago, Paul G said:

the undocking is so energetic my rover is flung to the floor and explodes, or tips my lander over (on Minimus) if I release whilst landed.

There must be a more elegant way of getting a rover down safely., but I can't see how I would release it - should I be looking at using hinges to make doors/ramps to a space in my lander where the rover sits until I'm landed, or should I be building rovers as landers in their own right?

A decoupler with its force set to 0 should work much better; it will apply no impulse and simply let go of the rover to fall under gravity. Forceless decoupling is also useful for deploying satellites in specific orbits. You might need to enable the 'advanced tweakables' setting to see the force slider. Remember to set in the VAB because you can't change it in flight.

Having a whole compartment for the rover that it can drive out of is great for safety and keeping it in line with the lander's centre of mass, but the added dry mass will impact the lander's DV and TWR. That kind of thing is better for atmospheric landings and much larger lander & rover combos.

You might want to change your lander's layout to have the engines closer to the far edges of the craft, with the rover in the centre. You can attach things (like the legs) to the casings of the Thud engines, placing them even further out for maximum stability, but it might be a bit ugly. You don't need as many solar panels on the lander as you have (unless life support mods?) so feel free to remove either the static or deploying sets if you need more surface area.

[Zhetaan]

20 hours ago, Paul G said:

My rover is secured via a docking port, and whilst I can get to my final descent quite happily (politely ignoring the slight plume impingement on my rover if I manoeuvre the wrong way). I've tried slowing my descent to single figure ms at low heights <50m, or even landing and then undocking the rover, but the undocking is so energetic my rover is flung to the floor and explodes, or tips my lander over (on Minimus) if I release whilst landed.

Undocking should not be so energetic; even decouplers and separators of proper size should not cause explosions when releasing the rover on the ground.  Typically, such destructive force is caused by part clipping issues.  Part clipping occurs when two parts occupy the same space; normally, it isn't a problem for two parts on the same vessel, because KSP ignores the case where a vessel collides with itself (this is necessary to keep the vessel in one piece), but as soon as you undock, you have two vessels that can collide with one another.  KSP's physics responds to collisions with a repulsive force, and in the case of a part intersection, that force becomes enormous.

20 hours ago, Paul G said:

There must be a more elegant way of getting a rover down safely., but I can't see how I would release it - should I be looking at using hinges to make doors/ramps to a space in my lander where the rover sits until I'm landed, or should I be building rovers as landers in their own right?

You can check in the VAB to see some possible part clipping issues, but one way to tell is to launch a test vehicle into orbit and to try undocking the rover there.  Have a quickload ready; there's no need to waste game resources for bug testing.  If the rover shoots away at high speed or explodes, then you likely have a clipping problem and will need to redesign to eliminate that problem.  It's not definitive--you may have a clipping issue that only appears when the landing leg settles under gravity, for example--but if the rover does shoot away, then it's a true positive.  For example, you can rearrange your lander so to eliminate a landing leg (tripods are perfectly stable provided that they are properly under the centre of mass) and put your rover in the free space thus created.

Another possibility is to turn your science station into something more resembling a skycrane by moving the Thud engines outwards and the rover towards the centre.

Yet another possibility is to move your return capsule to the side (atop one of the Science Jr. modules) and to move the rover to the other side, for balance.  Since both the rover and the return capsule will decouple, it won't even ruin the overall aesthetic.  Driving off of the top of the science station to an intact landing may be an act better reserved for Minmus than the Mun, though.

[Paul G]

On 4/7/2020 at 3:39 AM, Rocket Witch said:

A decoupler with its force set to 0 should work much better; it will apply no impulse and simply let go of the rover to fall under gravity. Forceless decoupling is also useful for deploying satellites in specific orbits. You might need to enable the 'advanced tweakables' setting to see the force slider. Remember to set in the VAB because you can't change it in flight.

Having a whole compartment for the rover that it can drive out of is great for safety and keeping it in line with the lander's centre of mass, but the added dry mass will impact the lander's DV and TWR. That kind of thing is better for atmospheric landings and much larger lander & rover combos.

You might want to change your lander's layout to have the engines closer to the far edges of the craft, with the rover in the centre. You can attach things (like the legs) to the casings of the Thud engines, placing them even further out for maximum stability, but it might be a bit ugly. You don't need as many solar panels on the lander as you have (unless life support mods?) so feel free to remove either the static or deploying sets if you need more surface area.

The decoupler worked, but I think you are right about the clipping - that is the source of my explosions. I will se what redesign I can come up with that puts the engines on the outside as I could do with the stability - especially when landing on the Run, things get very dicy on touchdown.

[MichaelMoore]

On 4/6/2020 at 10:04 PM, Paul G said:

Running the following on MacOS:

• Kerbal 1.9.1.2788
• Making History 1.91
• Breaking Ground 1.41

I'm reasonably advanced in the Tech tree - I have unlocked the bits necessary to build a rover, but I'm struggling to come up with a reliable way of getting a rover to my destination.

My lander shown below, will land me on the Mun or Minimus, and allow me to leave the base of the lander behind (with a scientist), and return the science I collect back to Kerbin.

My rover is secured via a docking port, and whilst I can get to my final descent quite happily (politely ignoring the slight plume impingement on my rover if I manoeuvre the wrong way). I've tried slowing my descent to single figure ms at low heights <50m, or even landing and then undocking the rover, but the undocking is so energetic my rover is flung to the floor and explodes, or tips my lander over (on Minimus) if I release whilst landed.

There must be a more elegant way of getting a rover down safely., but I can't see how I would release it - should I be looking at using hinges to make doors/ramps to a space in my lander where the rover sits until I'm landed, or should I be building rovers as landers in their own right?

Thanks

Paul

 

 

It's literally impossible