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aluc24

How the *peep* do I stop that LY-10 landing gear from bouncing?

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Posted (edited)

I run KSP 1.2.2 with a bunch of mods, but none that would influence this. All I want to do is build a small plane with LY-10 gear. Now, regardless of what suspension settings I use, my plane always bounces on touchdown. It has 4 undercarriages - two on wings, one on the nose, and one below the engine, just to protect it (it doesn't touch the ground). I slow my plane down to 55 m/s (just a little above stall speed), and descend at 0,5-1 m/s. Main wheels touch down, okay. Nose wheel touches down, and then it sends the nose flying into the air, as if some bomb exploded under it. It is obvious that the plane shoots up with far more kinetic energy than it had on landing.

I don't get this problem with any other gear (medium, large, extra large), just the small one, LY-10. I tried all suspension combinations - default, default springs + low dampener, default spring + high dampener, low spring + high dampener, low spring + low dampener, high spring with high dampener, high spring with low dampener... Nothing works. Sometimes it only makes it even bouncier.

How the heck do I use this landing gear? I've been working on my plane design for 3 hours now. When I land, I do so as slowly as possible, with very, very gentle vertical speed. And yet, it bounces, crashing my plane.

P.S. Before someone says it - the plane is level on the ground, meaning nose is at 0° pitch.

Edited by aluc24
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I personally find that increasing the load per gear may help in this case. Increasing both spring and damper might also help.

(I assume the LY-10 is the small retractable gear) Though this one is not the one I have most problem with, it usually behaves fine. The "wheel-on-a-stick" one gives me the most trouble.

Wheels are kind of wonky, so there's no definite solution to this. Make sure that the gear have plenty of clearance (much more than the physical size of the gear) because that is known to cause issues, but other than that I don't really know what else to do.

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Try disabling its brakes.

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Posted (edited)

3 hours ago, Gaarst said:

I personally find that increasing the load per gear may help in this case. Increasing both spring and damper might also help.

(I assume the LY-10 is the small retractable gear) Though this one is not the one I have most problem with, it usually behaves fine. The "wheel-on-a-stick" one gives me the most trouble.

Wheels are kind of wonky, so there's no definite solution to this. Make sure that the gear have plenty of clearance (much more than the physical size of the gear) because that is known to cause issues, but other than that I don't really know what else to do.

Well, my plane is only 3 tons, and I'd like to keep it that way... Lightweight exploration bird, you know? Clearance is plenty. I tried increasing both springs and dampener, but it only makes the wheels jumpy.

"Kind of wonky" doesn't even begin to describe it... I mean, they are unusable for light planes as they are now.

3 hours ago, Aperture Science said:

Try disabling its brakes.

I land with brakes off, and only turn them on after the vessel is stable on the ground.

Edited by aluc24

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Check the gear for part clipping.

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1 minute ago, Aperture Science said:

Check the gear for part clipping.

Checked... No clipping.

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7 minutes ago, aluc24 said:

Checked... No clipping.

Check if the landing gear is plugged in, and if it is try turning it off and on again.

If your problem is not solved, contact our toll-free LY-10 custumer support hotline: 1-800-LY-GEAR

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Just now, Aperture Science said:

Check if the landing gear is plugged in, and if it is try turning it off and on again.

If your problem is not solved, contact our toll-free LY-10 custumer support hotline: 1-800-LY-GEAR

Lol :D So, what's up with these wheels anyway? It has been a problem for as long as I can remember, why doesn't Squad fix this? Is this another "Unity bug"?

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The landing gear have never really been the same since the Unity 5 update.  I'm not sure there is much you can do about it.

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Just now, Alshain said:

The landing gear have never really been the same since the Unity 5 update.  I'm not sure there is much you can do about it.

What exactly broke it? Can we expect it to be repaired anytime in the near future?

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Posted (edited)

3 minutes ago, aluc24 said:

What exactly broke it? Can we expect it to be repaired anytime in the near future?

Ok, well they do have issues but truthfully your problem is probably piloting.  They usually bounce if you come down at too high a vertical speed but not high enough to break them.  You need to have a very low vertical speed when you hit the runway.  I feel most likely that is the issue you are facing.

The bouncing I'm referring to is something different now that I reexamined your original post. (sorry, I jumped to a conclusion I shouldn't have)

Edited by Alshain

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Just now, Alshain said:

Ok, well they do have issues but truthfully your problem is probably piloting.  They usually bounce if you come down at too high a vertical speed but not high enough to break them.  You need to have a very low vertical speed when you hit the runway.  I feel most likely that is the issue you are facing.

I am landing with 0,5-1m/s vertical speed at most, 60m/s horizontal speed at flat land. I even tried landing at 0,1m/s in Kerbin's Poles with Pilot's Assistant, and still crashed because of the bounce. So I don't think the piloting is the problem. With larger gear, I can come crashing down 5m/s vertical at 100m/s horizontal at hills, and have no bounce at all.

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Posted (edited)

Have to agree with Alshain on that. Bounce is usually because you came in to hard. But, since you mentioned soft landings. The other is colision detection of the wheels to ground could still be off.

Basicly you need to come in very very level with the ground. Think instead of nice round wheels to land on. Think landing on square blocks.

Edited by Aragosnat

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1 minute ago, Aragosnat said:

Have to agree with Alshain on that. Bounce is usually because you came in to hard. But, since you mentioned soft landings. The other is colision detection of the wheels to ground could still be off.

Basicly you need to come in very very level with the ground.

Please see my reply just above yours...

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1 minute ago, aluc24 said:

Please see my reply just above yours...

I did. And was busy editing the thing while you quated a bit of my answer.  Even if you think it is level just a slight bit off on the ground will likely make it bounce. Due to collision detection of the wheels being more like a square then a circle.

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2 minutes ago, Aragosnat said:

I did. And was busy editing the thing while you quated a bit of my answer.  Even if you think it is level just a slight bit off on the ground will likely make it bounce. Due to collision detection of the wheels being more like a square then a circle.

Well, if I'm already landing at absolutely minimum vertical speed and completely flat land, what else can I do? As I said, any other larger gear can take massive crashes without toppling the plane, but with LY-10m no matter how careful I am, the plane still goes over 90% of the time.

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Posted (edited)

Can you post a screenshot of your plane with the CoM marker turned on and the gear easily visible.  It's possible you have too much mass on the nose.

Edited by Alshain

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1 minute ago, Alshain said:

Can you post a screenshot of your plane with the CoM marker turned on and the gear easily visible.  It's possible you have too much mass on the nose.

Sorry, I'm now on another computer with no KSP. The CoM marker is just a little forward of the main (wing-attached) gear. The front gear is as far from CoM as it could be.

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1 minute ago, aluc24 said:

The front gear is as far from CoM as it could be.

That's the issue.  The further it is from the center of mass, the more the plane bears down on it. Move the front wheel back a bit.  Not so far back that it becomes horizontally unstable, but enough that the mass is better spread between the 3 wheels.

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2 minutes ago, Alshain said:

That's the issue.  The further it is from the center of mass, the more the plane bears down on it. Move the front wheel back a bit.  Not so far back that it becomes horizontally unstable, but enough that the mass is better spread between the 3 wheels.

Okay, I will try that when I get back. But the plane is already horizontally unstable (doesn't want to keep heading on ground).

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Also what this the front wheel attached to? As some of the parts do have a very slant on them. But, what Alshain suggested should also work.

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Posted (edited)

That could be caused by excessive mass on the front wheel too.  The front wheel has to steer but it can't do it's job if it's carrying most of the plane's mass.

The best way to thing about this is is a fulcrum.  Your rear wheels are nearly at the center of mass, making them the fulcrum.  So if you apply a little bit of force near the fulcrum, the fulcrum itself will take some of that force, but if you apply that same force further from the fulcrum, the lever swings easily.  In many uses of a fulcrum, that is what you want (this includes take off!)  Of course in this instance you don't want the lever to swing because that means all the mass is on the front.  So move your force closer and the problem resolves.  It's a bit backward from your typical lever logic, but it's still relevant.

Edited by Alshain

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3 minutes ago, Aragosnat said:

Also what this the front wheel attached to? As some of the parts do have a very slant on them. But, what Alshain suggested should also work.

Well, to this round-cone fuel tank that goes from 1.5m part to 0.625m part. The wheel is aligned to the ground.

1 minute ago, Alshain said:

That could be caused by excessive mass on the front wheel too.  The front wheel has to steer but it can't do it's job if it's carrying most of the plane's mass.

The best way to thing about this is is a fulcrum.  Your rear wheels are nearly at the center of mass, making them the fulcrum.  So if you apply a little bit of force near the fulcrum, the fulcrum itself will take some of that force, but if you apply that same force further from the fulcrum, the lever swings easily.  In many uses of a fulcrum, that is what you want (this includes take off!)  Of course in this instance you don't want the lever to swing because that means all the mass is on the front.  So move your force closer and the problem resolves.

Okay, I will try that. But what about horizontal stability? Even now, the plane is very hard to keep on the runway, it wants to steer off. If I bring front gear closer to CoM, won't the issue become worse?

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Moving to Gameplay Questions.

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Posted (edited)

5 minutes ago, aluc24 said:

 

Okay, I will try that. But what about horizontal stability? Even now, the plane is very hard to keep on the runway, it wants to steer off. If I bring front gear closer to CoM, won't the issue become worse?

Again, this problem also causes steering issues.  That's not what I mean by horizontal stability.  What I mean by that is rocking back and forth on the rear wheels because there isn't a successful tripod.

Unfortunately the LY rear gear have a tendency to do this anyway, that's the bounce issue I was referring to earlier.

Edited by Alshain

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Increasing the dampening helps. Usually I set my rear LY gear to 1.4 for springs and 1.45 for dampening. Seems to help quite a bit.

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