Rolled down a hill, BOOM

[Loren Pechtel]

Do I have to put legs on anything round to avoid this?  (Capsule + 2-Kerbal crew cabin.)  It came down on a hillside, rolled and for some reason blew up--I think it might have jumped slightly due to a slope change but it couldn't actually have hit hard.  (I'm guessing the game engine only looks at total velocity, not that that velocity was almost all parallel to the terrain and it was already spinning at a velocity to match.)

[Starwaster]

26 minutes ago, Loren Pechtel said:

Do I have to put legs on anything round to avoid this?  (Capsule + 2-Kerbal crew cabin.)  It came down on a hillside, rolled and for some reason blew up--I think it might have jumped slightly due to a slope change but it couldn't actually have hit hard.  (I'm guessing the game engine only looks at total velocity, not that that velocity was almost all parallel to the terrain and it was already spinning at a velocity to match.)

I'd say landing on a hill is also something to avoid in the future. 

And if you're talking about the hitchhiker's pod, yes, it definitely needs legs. It has a very low pain threshold.

Capsules? Sturdier, but don't land them on hills.

[N_Danger]

 Legs may not help that much any more with hills.

The thing with hills now is friction (or the lack of) affecting wheels or landing legs is much more important. I landed on Duna the other day and slid down a hill at 1 m/s for a good while. Thankfully the chutes didn't cut away(because they kept my velocity from increasing) due to the fact I never came to a 0 velocity after touchdown until after the slide.

[Loren Pechtel]

11 minutes ago, N_Danger said:

30 minutes ago, Starwaster said:

I'd say landing on a hill is also something to avoid in the future. 

And if you're talking about the hitchhiker's pod, yes, it definitely needs legs. It has a very low pain threshold.

Capsules? Sturdier, but don't land them on hills.

 

11 minutes ago, N_Danger said:

 Legs may not help that much any more with hills.

The thing with hills now is friction (or the lack of) affecting wheels or landing legs is much more important. I landed on Duna the other day and slid down a hill at 1 m/s for a good while. Thankfully the chutes didn't cut away(because they kept my velocity from increasing) due to the fact I never came to a 0 velocity after touchdown until after the slide.

 Legs may not help that much any more with hills.

The thing with hills now is friction (or the lack of) affecting wheels or landing legs is much more important. I landed on Duna the other day and slid down a hill at 1 m/s for a good while. Thankfully the chutes didn't cut away(because they kept my velocity from increasing) due to the fact I never came to a 0 velocity after touchdown until after the slide.

How do you avoid landing on a hill, though?  I had no idea that's where I was going to come out of the fire.

And the idea of landing legs was not to keep it from tipping, but to make it not round so it wouldn't roll.

[Starwaster]

6 minutes ago, Loren Pechtel said:

How do you avoid landing on a hill, though?  I had no idea that's where I was going to come out of the fire.

Then I'd say you have your work cut out for you. You need to work on your targeting so you can hit plains or water (obviously not water on Duna) instead of hills. Maybe offset your center of mass so that you can do lifting reentries. Or add some winglets for gliding capabilities. Or airbrakes. (hint: airbrakes can be used as control surfaces - make sure yaw/pitch are enabled for them)

Personally, for Duna I prefer one of the canyons. I even have a favorite: 

Once you clear the cliff on reentry, the canyon has a nice reasonably flat floor.

[Loren Pechtel]

3 minutes ago, Starwaster said:

Then I'd say you have your work cut out for you. You need to work on your targeting so you can hit plains or water (obviously not water on Duna) instead of hills. Maybe offset your center of mass so that you can do lifting reentries. Or add some winglets for gliding capabilities. Or airbrakes. (hint: airbrakes can be used as control surfaces - make sure yaw/pitch are enabled for them)

Personally, for Duna I prefer one of the canyons. I even have a favorite: 

Once you clear the cliff on reentry, the canyon has a nice reasonably flat floor.

 

I at least have the option of picking a target as I'm currently only coming in from orbit.  Until this case of rolling down a hill the only issue has been coming down over mountains and not slowing enough for the chutes--solved with a drogue.  No airbrakes yet--I only have a few of the 90-point column unlocked.

[N_Danger]

9 hours ago, Loren Pechtel said:

How do you avoid landing on a hill, though?  I had no idea that's where I was going to come out of the fire.

And the idea of landing legs was not to keep it from tipping, but to make it not round so it wouldn't roll.

 A crater works well most times. I was actually going for one and over shot the intended LZ when I came down on the slope. And I think you would have the problem, if using landing legs, of no traction. You are still sliding and picking up speed until you go fast enough to damage a component.

[Loren Pechtel]

1 hour ago, N_Danger said:

 A crater works well most times. I was actually going for one and over shot the intended LZ when I came down on the slope. And I think you would have the problem, if using landing legs, of no traction. You are still sliding and picking up speed until you go fast enough to damage a component.

So you're saying that legs won't stop a *roll*??

[Warzouz]

10 hours ago, Loren Pechtel said:

How do you avoid landing on a hill, though?  I had no idea that's where I was going to come out of the fire.

And the idea of landing legs was not to keep it from tipping, but to make it not round so it wouldn't roll.

KER has slope related data which is VERY useful. When KER says you'll land on a 45° slope, time to light you engine and burn sideway or pray your ship is well designed (but with the actual strut bugs, it won't save you...).

Eye-balling is possible but it's usually had to distinguish slopes from flat terrain until very near ground.

You can still use the "touch and go" manoeuvre : land on the slope, let your lander contact with the terrain, and fire engines before it fall or slide. You'll be going down the slope, hoping for a flatter terrain to land on. Viable if you have reasonably high torque.

Either way, it's always easier to change landing location when your trajectory is not vertical. Shallow landing is easier to tweak at the last minute. It'll cost more for a vertical approach.

Edited May 9, 2016 by Warzouz

[Snark]

12 hours ago, Loren Pechtel said:

And the idea of landing legs was not to keep it from tipping, but to make it not round so it wouldn't roll.

I'm having trouble following this-- goodness knows I've had my share of hilarious failure modes on landing, but "the craft rolls faster until it dies" has never been one of them.

I just turn on SAS and it stops the roll right there.

Or, if I've come down on a hill that's so steep that the rolling-downhill torque is greater than SAS can handle... I just use SAS to muscle the craft around so that its "roll direction" is sideways to the slope rather than straight downhill.  That turns a rolling problem into a sliding problem, which can be more manageable.  (Particularly if my craft has a functioning engine and I can point it downhill.)

[Loren Pechtel]

1 hour ago, Warzouz said:

KER has slope related data which is VERY useful. When KER says you'll land on a 45° slope, time to light you engine and burn sideway or pray your ship is well designed (but with the actual strut bugs, it won't save you...).

Eye-balling is possible but it's usually had to distinguish slopes from flat terrain until very near ground.

You can still use the "touch and go" manoeuvre : land on the slope, let your lander contact with the terrain, and fire engines before it fall or slide. You'll be going down the slope, hoping for a flatter terrain to land on. Viable if you have reasonably high torque.

Either way, it's always easier to change landing location when your trajectory is not vertical. Shallow landing is easier to tweak at the last minute. It'll cost more for a vertical approach.

Engine?  What engine?  This happened coming back to Kerbin.

Avoiding too-steep terrain isn't that hard when you have a rocket under you.

[KocLobster]

13 hours ago, Starwaster said:

Then I'd say you have your work cut out for you. You need to work on your targeting so you can hit plains or water (obviously not water on Duna) instead of hills. Maybe offset your center of mass so that you can do lifting reentries. Or add some winglets for gliding capabilities. Or airbrakes. (hint: airbrakes can be used as control surfaces - make sure yaw/pitch are enabled for them)

Personally, for Duna I prefer one of the canyons. I even have a favorite: 

Once you clear the cliff on reentry, the canyon has a nice reasonably flat floor.

That's one of my favorite spots too!

[MaxwellsDemon]

On 5/8/2016 at 11:33 PM, N_Danger said:

 Legs may not help that much any more with hills.

The thing with hills now is friction (or the lack of) affecting wheels or landing legs is much more important. I landed on Duna the other day and slid down a hill at 1 m/s for a good while. Thankfully the chutes didn't cut away(because they kept my velocity from increasing) due to the fact I never came to a 0 velocity after touchdown until after the slide.

Had something like this happen to me on Minmus yesterday.   My lander's COM was low enough and the 'splay' of the legs great enough that it didn't have trouble staying upright on the slope (which IMHO wasn't that severe-- maybe 20 degrees?) but I suddenly realized that the lander was slowly drifting down the hill.  I had my pilot scramble aboard again from her EVA and made an emergency takeoff, but, apart from avoiding landing on slopes in the future, I'm not quite certain what the remedy is.

[Loren Pechtel]

37 minutes ago, MaxwellsDemon said:

Had something like this happen to me on Minmus yesterday.   My lander's COM was low enough and the 'splay' of the legs great enough that it didn't have trouble staying upright on the slope (which IMHO wasn't that severe-- maybe 20 degrees?) but I suddenly realized that the lander was slowly drifting down the hill.  I had my pilot scramble aboard again from her EVA and made an emergency takeoff, but, apart from avoiding landing on slopes in the future, I'm not quite certain what the remedy is.

I've found getting aboard to be very dangerous.  If the sliding rocket touches the Kerbal the rocket will be damaged.  So long as there's nothing nearby too steep (and I haven't seen any such spot) you can just let it slide.

[coredumpster]

The ever versatile cargo bay can help here.  If you open the doors on the cargo bay, it will stop your craft from rolling sideways.  

Very useful for early tech tree in career where you don't yet have good landing legs unlocked.

[N_Danger]

On 8/2/2016 at 6:14 AM, MaxwellsDemon said:

Had something like this happen to me on Minmus yesterday.   My lander's COM was low enough and the 'splay' of the legs great enough that it didn't have trouble staying upright on the slope (which IMHO wasn't that severe-- maybe 20 degrees?) but I suddenly realized that the lander was slowly drifting down the hill.  I had my pilot scramble aboard again from her EVA and made an emergency takeoff, but, apart from avoiding landing on slopes in the future, I'm not quite certain what the remedy is.

My worst was on Eve. The lander eventualy ran over my flag. And trying to climb back up, while the ship was moving, was difficult. 140 tons landed and sliding at .8 m/s on a less than 15 deg slope. I did get the science though.

[fourfa]

At least the landers seem to have stopped sliding uphill? That was a bit startling in the pre-release of 1.1

[Magzimum]

On 9-5-2016 at 5:45 AM, Loren Pechtel said:

How do you avoid landing on a hill, though?  I had no idea that's where I was going to come out of the fire.

And the idea of landing legs was not to keep it from tipping, but to make it not round so it wouldn't roll.

Although I am a newbie, let me try to give you an answer.

At first, Kerbin re-entry is a toss of the coin. You get yourself into the atmosphere, and the atmosphere will slow you down and will choose your landing spot for you... But if you play a little longer (I have been playing for roughly a month now), you start noticing that your landing spot is always a certain distance away from the point where you enter the atmosphere. It depends on a lot of things, such as the angle at which you enter the atmosphere and the weight/aerodynamics of the craft, but there is something predictable about it.

Next, rather than try to avoid hills, which is difficult, just try to hit the ocean, which is a large target.

Some of the experts here can probably land a ship on the launchpad, but I am happy if the ship stays retrograde, and does not explode. So I just aim for daytime landings, on the ocean, or on large patches of flat land. And I still get it wrong sometimes. In that case, the quicksave is my friend.

As for the rolling: if your ship does not tip, it does not roll. Put the parachutes at a point well-above the center of mass, and it should come down bottom first.

 

 

Edited August 4, 2016 by Magzimum