Why can't I land a plane?

[Jetski]

Is anyone else having trouble with landings that worked ok previous to 1.1?  I've stayed away from landing gear and planes in general until 1.13 which fixed everything, but now I'm really struggling get to ng back into it. Every plane I make instantly cartwheels forward and explodes when the gear touch down. Doesn't matter if front gear touch first or back gear or both together, the plane always does exactly the same thing. Also it does it on upward slope, flat ground, or downward slope. On a Duna spaceplane and on a super low tech jet landing on Grasslands next to KSC. Always the same behavior. Drogue chutes or no drogue chutes. F3 menu just says capsule crash and pilot killed, no wheel errors or notices. 

Is anyone else experiencing this? Is there something simple I'm missing?

[cantab]

Because the wheels still aren't properly fixed. That's expected in KSP 1.2.

I know someone's going to chime in and say that they made it work, and they're right. But my opinion is that the hardest part of designing a drone that weighs under a ton should not be the freaking landing gear. Yet I ended up with one that's unlandable except by using a chute.

Edited July 4, 2016 by cantab

[Rocket In My Pocket]

Can't say I've had this issue.

Are you landing with the breaks on and set to 200 or something? Have you tweaked the friction settings perhaps?

Whats your vertical/horizontal speed when landing?

Edited July 4, 2016 by Rocket In My Pocket

[Jetski]

Tried a few speeds, vertical always as near 0 as I can get, horizontal from 26 to 55 ms near ksc with beginner wheels, Duna plane around 40-65 with retractable landing gear. Tried a few things, brakes vs no brakes vs back wheel brakes only, fiddled with friction settings but didn't see a difference.  I literally can't land even the simplest plane.

Lots of plane landings in previous versions, and I lined up the landing gear using rotation tool set to absolute mode, so no misaligned gear.

Edited July 4, 2016 by Jetski

[Rocket In My Pocket]

Are these planes using a tricycle (2 gear just behind COM, 1 gear in nose) or tail dragger (2 gear just ahead of COM and 1 gear in the tail) landing gear setup?

Do you have any reaction wheels? They could be flipping the plane when you are trying to hold the nose down.

Do the landing gear say "blocked" at any point? Could be that the ground is pushing the suspension up into another part and causing them to lock up.

[Jetski]

Duna plane tricycle style, local ksc explorer plane is 4 ly-01 wheels, 2 way out and forward on the wings, 2 just aft of COM on fuselage. Only reaction wheels is internal pod. It's pretty much an instantaneous flip forward on touchdown. Like the front wheels are locked up or something, even if they don't touch down first.

[Rocket In My Pocket]

Definitely sounds like they are blocked, you can right click them on the launchpad or in flight to find out. It'll say "Gear Blocked: Yes/No."

Try moving them away from other parts and further out from the body of the plane.

The LY-01 is definitely the buggiest of the wheels currently in my experience.

[Jetski]

Hmmm. Reloading the pane and taking screenshots shows my front landing gear are slightly higher than aft. snap aligned correctly, but definitely higher, as they are attached to the front of a wing i tweaked up for better AOA. Giving me a plane that lands a little down by the nose. Perhaps that's the issue, I'll test more. Im thinking the new gear has more spring to it, and im losing ground clearance from that. No idea why the Duna plane can't land though, maybe too much speed? Hard to bleed off enough horizontal velocity and get below 60ms or so. I haven't landed many planes on Duna before this. 

Edited July 4, 2016 by Jetski

[Xyphos]

3 hours ago, Jetski said:

Hard to bleed off enough horizontal velocity and get below 60ms

don't do that. your horizontal speed is what is keeping you aloft.

a plane's wing is flat on the bottom and curved on the top, this creates more surface area on the top of the wing than under it,
this makes it so that that horizontal air flowing over the wing takes longer to travel than under it, and that means
there's less air pressure on the top of the wing than under it, which gives you lift and keeps you up.

since your problem is your craft slamming into whatever and exploding, you want to bleed off your vertical speed but keep your horizontal above 80 m/s.
as you're landing, set your navball to surface mode, get below 2000 meters on your final approach, lower your landing gear,
throttle down to 15% (powered landings only, gliders skip this step)
then nose-up to about 10 degrees or less and watch your navball. you want to keep your prograde marker just under the horizon but not too much that you're falling like a rock.
if you're gaining speed, continue to throttle down until your speed starts to bleed off, but not too rapidly, just enough to give the ground a soft tender kiss with your wheels.

after you've landed, stopping your vessel is an entirely different story; in KSP the brakes system doesn't work too well and has varying effect on different celestial bodies,
in conjunction with the new friction control system, the brakes are next to worthless, just put some chutes on a stage and deploy when you want to stop. optionally re-pack and add them to a new stage if you're going to re-use the vessel.

[FullMetalMachinist]

@Xyphos, while the majority of your reply is very good advise, this part:

4 hours ago, Xyphos said:

a plane's wing is flat on the bottom and curved on the top, this creates more surface area on the top of the wing than under it,
this makes it so that that horizontal air flowing over the wing takes longer to travel than under it, and that means
there's less air pressure on the top of the wing than under it, which gives you lift and keeps you up.

isn't close to correct, at least for KSP. 

KSP does not model the airfoil lift that you describe here. Wing parts can generate lift only from Newtonian lift. That is, a surface that is at an angle to the airflow (angle of attack) directs the air down, and at the same time experiences and equal and opposite force up. 

For that reason, it's usually at good idea to build your plans with some angle of attack on the main wings to give lift while the rest of the plane is straight. 

[Xyphos]

34 minutes ago, FullMetalMachinist said:

isn't close to correct

real-world, it's correct.
in KSP, a cardboard box will fly to minmus if you find a big enough rubber band to hurl it with.

Edited July 5, 2016 by Xyphos

[The_Rocketeer]

@FullMetalMachinist@Xyphos

Simple Newtonian physics: wing pushes air down therefore air pushes wing up. Simple really, and even KSP does lift pretty much on this mathematical basis.
 

@Jetski:

A screen of the aircrafts might reveal a lot.
Gears and wheels are still fundamentally borked, but there are ways to deal with it - using many where you would use one often solves issues.
Have u installed Claw's Stock Bugfix Modules?
Failing all that, can u offer that .craft so we can test? It seems very likely that the solution will be found in design revision rather than waiting for an update, but the easiest way to see if it is unsolvable/ur own system causing hiccups would be for someone else to try out your planes.

[Xyphos]

@The_Rocketeer - THIS is what was taught to me in school, so this is all I have to go by. https://en.wikipedia.org/wiki/Lift_(force)#False_explanation_based_on_equal_transit-time

but I thank you, because you've made me do research on the subject, only to find out that my high-school science teacher is a babbling idiot, and taught me nothing worth using.

Edited July 5, 2016 by Xyphos

[Snark]

Moving to Gameplay Questions.

[bewing]

In general, as @Rocket In My Pocket said, the cause of the problem you are describing is wheel blocking, which comes as a result of clipping wheels into other parts when you build the plane in the SPH.

When the game determines that a wheel has been clipped "too much", it marks the wheel as being blocked, and the wheel doesn't spin anymore. So you end up trying to land on metal sticks instead of wheels. And when you jam the metal sticks into the ground at 50 m/s, you tumble forwards. This is new functionality in KSP 1.1 that never existed before -- so yes, I've seen quite a few people having exactly this same issue.

So, overall, the answer is to minimize your use of wheel clipping. After testing a plane that has no wheel clipping at all, you can add a little at a time and make sure the plane still works.

But yes, if at all possible, post a .craft file. Your plane can probably be fixed with just a few minor tweaks. I fly all kinds of things in 1.1.3 -- it's not really very hard to make planes work.

[Hodo]

I recent had problems landing craft also, but I use FAR, and found that the landing gear are VERY touchy now.   So I found if I do a much softer landing it works way better.

Less than 7m/s decent speed on most craft.   But I also had to adjust the stiffness and damper settings on them. 

 

Brakes are still a problem so I use drag chutes... 

Edited July 5, 2016 by Hodo

[Corona688]

Landing gear are bugged.  Try right-clicking on your landing gear before taking off, and seeing if any of your gear parts have a huge pile of force on them for no reason.  Those are bugged.  If you delete and re-add the part, it sometimes goes away.

I suspect, but can't prove, that it's related to wonky mirroring in the spaceplane hangar, you have to add them to the "correct" side.  Have you ever had to spam asdqw to get the landing gear even pointed down?  That's what I'm talking about.  It can even happen to unmirrored parts.