The Landing Legs & Gears Is Killing Me!

[Tyko]

22 hours ago, Rocket In My Pocket said:

Link it to me and I'd be happy to. Not sure which post you are talking about, didn't notice any lander .craft files.

On a side note; here's another test I did after the first two just for fun. This time I moved the Poodle's up so there was no chance the bell was interfering, made the craft 8 times as large/heavy, impacted at about 3 m/s instead of 0.1, and did it with the entire craft at a 45 degree tilt, and the landing area was a slope itself. (Also in the dark, but that's irrelevant lol.) SAS off, RCS off, I just watched. Slid a ways, bounced very gently a few times (about .50mm/s upwards vertical speed at worse according to KER) and landed safely.

  Reveal hidden contents

 

Interestingly I've experienced my first really bouncy landing issue in 1.4.5. I'm using a very small lander that's nearly identical to early landers in previous games. It didn't bounce excessively in previous games, but now it just pogos forever.

In reading this I realized I'd used WorldStabilizer previously, but not in this save, so I'm going to try that tonight.

[Majorjim!]

These issues are confirmed by Squad and will be somewhat fixed in the next patch.

[Dafni]

5 minutes ago, Majorjim! said:

These issues are confirmed by Squad and will be somewhat fixed in the next patch.

once more

 

[OHara]

On 10/4/2018 at 2:42 AM, AVaughan said:

For people having trouble with landing on Gilly, what touchdown velocity are you using?

0.1m/s.  I looked more closely and see what is going on.  The physical spring stiffness in N/m and damping in N/(m/s) are automatically adjusted for the local gravity, and it seems the stiffness is reduced in proportion with the gravity, so on Gilly it is to 0.5% the stiffness on the launchpad.  So when we touch down we think the landing gear will push back but they don't and even 0.1m/s bottoms out the struts.  When bottoming out, there is a large force for probably one time-step that sends the craft up at 8 m/s.

In version 1.3.1, the craft jump off of the planet upon loading the scenario 'Exploring Gilly' and that is what the World Stabilizer mod was for.  We can easily land the Vules Jerne  craft with legs down, however, because the legs retain the stiffness (or at least the damping) they had on the launchpad.I can see why players might want auto-adjusting stiffness, so they don't need to remember that springs will compress more on Eve, but do not see why the damping force need be adjusted.  

I looked for the switch to turn off auto-adjusting, and found 'useAutoBoost'. Setting this to false does not affect the automatic adjustment of stiffness/damping for load, but it does prevent the 8 m/s jump upon bottoming out, and the one type of oscillation that involves hitting the stops of the landing gear.  

Spoiler

@PART[*]:HAS[@MODULE[ModuleWheelSuspension]] {
	@MODULE[ModuleWheelSuspension] {
		useAutoBoost = false }}

 

But the original poster's problem was the growing smooth oscillation that we often see in the early aircraft gear (and these have useAutoBoost=false by default).  

I suspect this is due to the automatic adjustment of the springs for their load, sensing the load based on the compression of the spring.  Such a system would strengthen the spring when it is compressed, weaken when it is extended.  There will be a little lag due to time averaging the state of the strut, so our springs are a little stronger as our craft are bouncing up, pumping up the oscillation.

KSPWheel leaves such things under manual control.

[Foxster]

There is another good Unity-based bolt-em-together game out there: TerraTech. 

The wheels and suspension don't suffer from any of the glitches people see in KSP. I wonder why that is?

Edited October 7, 2018 by Foxster

[klgraham1013]

4 hours ago, Foxster said:

There is another good Unity-based bolt-em-together game out there: TerraTech. 

The wheels and suspension don't suffer from any of the glitches people see in KSP. I wonder why that is?

Game engine?  Wheels?  Developer?

One of these things is not like the others.

[Rocket In My Pocket]

Well, even if it doesn't seem to affect me, I'm still glad it's getting fixed for you guys!

[Shadowmage]

11 hours ago, OHara said:

I suspect this is due to the automatic adjustment of the springs for their load, sensing the load based on the compression of the spring.  Such a system would strengthen the spring when it is compressed, weaken when it is extended.

I can confirm that stock does exactly that....

Worse yet, there is some sort of stored heuristic value that can make the 'spring force' for symmetrical counterpart wheels have very different values depending on how the craft was driven previously.  I've been able to 'abuse' that function to get a symmetrical and balanced craft to tip over just from the wheels difference in spring force.

(e.g. if you constantly do a left-hand turn, compressing the right-side wheels for an extended period of time, and then return to straight driving or stop entirely -- your craft may no longer sit level, as the right side wheels will have a higher spring value than the left; it will, eventually, return to balanced... but still... absolutely not a physically accurate wheel simulation)

 

6 hours ago, Foxster said:

The wheels and suspension don't suffer from any of the glitches people see in KSP. I wonder why that is?

Actually -- they do.  Having played that game for quite a few hours, I noticed that while the wheels generally behave better than in KSP, many of the same underlying glitches are still present (I can easily make craft in TT that just jitter/bounce all over on their wheels).  What they don't do is pogo, or launch stuff into orbit -- I think

Better?  Sure -- but they also do another thing I've long said KSP should do -- have a single rigidbody for the entire vehicle rather than one per part.  It is this one-per-part rigidbody setup, with joints connecting everything, that make the wheels in KSP so unstable.  It is a Unity engine problem though, and can be easily duplicated in the Unity editor with very basic testing rigs.

[Majorjim!]

9 hours ago, Rocket In My Pocket said:

Well, even if it doesn't seem to affect me, I'm still glad it's getting fixed for you guys!

LOL, you just havent experienced it yet, I guess due to the variation in craft types. The issue is there for everyone though.

8 hours ago, Shadowmage said:

(e.g. if you constantly do a left-hand turn, compressing the right-side wheels for an extended period of time, and then return to straight driving or stop entirely -- your craft may no longer sit level, as the right side wheels will have a higher spring value than the left; it will, eventually, return to balanced... but still... absolutely not a physically accurate wheel simulation)

THIS!

why does this happen @squad??

[Rocket In My Pocket]

10 hours ago, Majorjim! said:

LOL, you just havent experienced it yet, I guess due to the variation in craft types. The issue is there for everyone though.

Well, after hours of intentionally trying everything that's been suggested to cause it and failing; it must be a pretty specific and obscure bug then?

[Xurkitree]

I don't experience much bouncing, except when i retract my landing gear-landing leg substitutes on my large VTVL SSTO which im using for a Grand Tour. In that case it just springs up in the air like its kicking the ground before retracting itself. And the only reason I need to retract them in the first place is because Wheel Brakes are just not cutting it.

CAN WE HAVE A BETTER SAFER BRAKE

 

[magnemoe]

On 9/28/2018 at 8:49 AM, steve_v said:

Welcome to post-1.1 KSP. Landing legs and gear have been borked in a variety of ways ever since the U5 "upgrade".
Since Squad seems to have no interest in fixing them properly, the only options I am aware of are to avoid using them entirely or spend considerable time tweaking the spring and damper settings... Which will trade slinky or pogo-stick for mound of jell-o if you are lucky.

Yes, stopped using legs on heavy landers a long time ago.
Now the weird thing is that I use the medium landing legs on an minmus science lander. its the Apollo LEM and 4x FL-T200 Fuel Tank the 90 fuel tank so not an heavy craft, 4 of the mediums legs and the engines touch the ground then landing at 4 m/s using mechjeb.

[Tyko]

On 10/7/2018 at 7:36 AM, Rocket In My Pocket said:

Well, even if it doesn't seem to affect me, I'm still glad it's getting fixed for you guys!

you may want to try with really light landers. I've launched a small lander that's identical to one I've used successfully since 1.3.x and only recently am I seeing issues.

[Vexillar]

On 10/7/2018 at 3:55 PM, Shadowmage said:

the right side wheels will have a higher spring value than the left;

Hey... does that mean that Kerbals are secretly into oval circuit racecars?

[Rocket In My Pocket]

1 hour ago, Tyko said:

you may want to try with really light landers. I've launched a small lander that's identical to one I've used successfully since 1.3.x and only recently am I seeing issues.

Hmm...interesting, everyone told me heavy landers were the cause of the issue. I'll give it a try when I get chance, just out of curiosity.

Although with the upcoming patch it's become a bit of a moot point.

Edited October 12, 2018 by Rocket In My Pocket

[Tyko]

4 minutes ago, Rocket In My Pocket said:

Hmm...interesting, everyone told me heavy landers were the cause of the issue. I'll give it a try when I get chance, just out of curiosity.

Although with the upcoming patch it's become a bit of a moot point.

yea, I'm hoping this question is academic in a few weeks. I'm sharing mine because I have an identical craft behaving differently rather than just a statement like "heavy landers" or whatever 

 

[Hodo]

It is odd, I have not had this issue.  But I do run a modded KSP with BDA phyx extender.  

But I have noticed on some of my wheeled craft if I leave them out and jump to space center then back to them miles away on the other side of Kerben they jump.

[I_Killed_Jeb]

On 10/8/2018 at 3:27 AM, Rocket In My Pocket said:

Well, after hours of intentionally trying everything that's been suggested to cause it and failing; it must be a pretty specific and obscure bug then?

Based on your screenshot you also run a heavily modded version of the game so your testing is not particularly relevant to the stock experience. Incidentally I noticed that after installing the forked KJR this problem was heavily mitigated.

[Cubivore]

Copied an old Mk2 spaceplane design I made years ago, took it to Minmus, landed, could barely take back off because at a stop the plane bounced so severely that I had to reload several times before I was able to get the thing moving and not have it bounce into the ground and explode. I understand for rockets that the current (stupid) work-around is to treat the game like it's the ancient version that didn't even have landing legs, but what in the world am I supposed to do if I'm using spaceplanes? Just don't build or use them? Whatever other bugfixes or additions that are in the pipes, not a single solitary one of them should be taking precedence over this bug. It is making me hate a game that I love and have spent thousands of hours playing.

Edited October 14, 2018 by Cubivore

[AVaughan]

@Cubivore.  There are apparently improvements to landing legs/gear coming soon with 1.5.  In general I always recommend posting screenshots/craft files when you are reporting problems.  Many issues are caused by poor design choices by players.

[Rocket In My Pocket]

12 hours ago, I_Killed_Jeb said:

Based on your screenshot you also run a heavily modded version of the game so your testing is not particularly relevant to the stock experience. Incidentally I noticed that after installing the forked KJR this problem was heavily mitigated.

I only use visual and UI mods, nothing game play altering, and no parts. (I don't use KJR either, whatever that is.)

So yeah, as far as physics and craft are concerned, it's 100% stock.

(We won't even get into the fact that most of the people claiming the bug affects them are likely playing saves that are actually heavily modded with parts and gameplay affecting mods.)

I'd be happy to test any craft any one wants, on a completely fresh, stock install. Despite the somewhat ..sarcastic responses I keep getting; I was only here to help pin down the cause of the bug so it could be fixed. (Despite it not ever affecting me.) Kind of a moot point now though with 1.5 claiming to have solved it. I guess we'll wait and see.

Edited October 14, 2018 by Rocket In My Pocket

[Cubivore]

9 hours ago, AVaughan said:

@Cubivore.  There are apparently improvements to landing legs/gear coming soon with 1.5.  In general I always recommend posting screenshots/craft files when you are reporting problems.  Many issues are caused by poor design choices by players.

I can guarantee you that this is not being caused by a bad design choice. This is a design I've used for years with no issue, and furthermore there is no design choice one could make with standard aircraft landing gear that would cause the ship to bounce around at a standstill if it weren't for this bug.

 

3 hours ago, Rocket In My Pocket said:

(We won't even get into the fact that most of the people claiming the bug affects them are likely playing saves that are actually heavily modded with parts and gameplay affecting mods.)

My only mods are Outer Planets and the associated Kopernicus, but by all means keep handwaving this away as an isolated problem caused by bad design choices or heavily modded installs if you must.

[Rocket In My Pocket]

37 minutes ago, Cubivore said:

My only mods are Outer Planets and the associated Kopernicus, but by all means keep handwaving this away as an isolated problem caused by bad design choices or heavily modded installs if you must.

I didn't hand wave anything, it's a bug; a bug in the stock game.

However like many bugs it seems to affect some players worse than others, and as I've already explained I'm just here to help investigate the cause of the issue. On my own time I might add, when I could be doing other things besides trying to trouble shoot a bug I've never even encountered.

[I_Killed_Jeb]

5 hours ago, Rocket In My Pocket said:

(We won't even get into the fact that most of the people claiming the bug affects them are likely playing saves that are actually heavily modded with parts and gameplay affecting mods.)

That's pure conjecture on your part, you realize that right?

 

1 hour ago, Rocket In My Pocket said:

I didn't hand wave anything, it's a bug; a bug in the stock game.

However like many bugs it seems to affect some players worse than others, and as I've already explained I'm just here to help investigate the cause of the issue. On my own time I might add, when I could be doing other things besides trying to trouble shoot a bug I've never even encountered.

Here's the thing my dude, no one asked you to help resolve or investigate this issue. You seem primarily intent on proving it doesn't happen, or at worst it's rare/not a big deal. That's fine and your prerogative, and I genuinely applaud your interest in the game, but don't act like you're doing anyone a favor here.

[FinalFan]

34 minutes ago, I_Killed_Jeb said:

Here's the thing my dude, no one asked you to help resolve or investigate this issue. You seem primarily intent on proving it doesn't happen, or at worst it's rare/not a big deal. That's fine and your prerogative, and I genuinely applaud your interest in the game, but don't act like you're doing anyone a favor here.

I don't see how he could be trying to "prove" it was rare based on his own personal experience. 

But if the fact that no one asked him to look into it is a problem for you, I can solve that.  Hey, @Rocket In My Pocket, I'm officially asking you to do exactly as much investigation into this matter as you happen to feel like doing.  Thanks. 

Happy now? 

(OK, time to be more serious.  Rocket seems to be trying to find out whether the issue can be consistently reproduced in certain circumstances (for example all stock, certain planet, certain vessel) and you can't seriously deny that this would be relevant information regardless of whether the answer is "yes" or "no".  And if the answer is "no", that doesn't somehow prove that your personal experience of the issue never happened, and I don't believe Rocket has ever said otherwise.)