Kerbal Space Program

I think this is very similar to #3309.

OK I just had the weirdest experience with this. I brought a badly balanced space plane in to land tail first, (engines are so heavy you have to put the wings right at the back and I didnt) and on a 270 approach but backwards all 4 of the small deltas collided with the Tier 3 launch pad in turn at irregular intervals about 2km out from the KSC.

With the wings evened up it was still just possible to crash land, lost the engine, but the craft chassis with three small gear bays was intact and it fell onto its wheels whereupon the craft was dragged by an unnaccountable force towards the shore as though down the slope but it would not steer and would not brake as the force was too strong. So I raised the undercarriage and the friction caused the craft to reluctantly come to rest on the gentle slope about 100-200m from the shore whereupon the force acted on it again and dragged it, as though by an invisible tentacle in playful mood, across the terrain in the direction of the slope with forces displayed far exceeding the physics of the craft's situation. It would move then stop and then move again, all with gear retracted as though something about the turning of Kerbin or the game tick was making it move periodically.

Something went really wrong there. I did manage to recover what was left of the craft during the stopped phase and switched to sandpit mode and took a wheeled buggy out to test the slope in that location and it was perfectly able to resist the slope with brakes on so there was a kraken like force at play on the first craft which reminds me a bit of the bugs we used to see when returning to KSC terrain after a long flight to a great distance frome Kerbin and the terrain would be jagged like a concertina, this craft had been out to just inside Mun orbit.

I will see if I can replicate, just thought I would add it in case others have the same kind of experience.

This has been acknowledged as happening occasionally. The cause is unknown, and any attempt to reproduce by others has proved fruitless. All we know is that it does happen, and that it is elusive.

To be able to identify the causes, we need to have game logs and reproduction steps. The logs may show how the problem manifested, and do need to be the complete log. What happens prior to the problem is also very important, so an account of what actions were performed in the run up to the event would be useful.

If you have a save game that can demonstrate this between game sessions/restarts, then it would be very useful.

Please feel free to attach the logs and saves.

[LOG 15:34:02.717] Camera Mode: AUTO
[LOG 15:36:30.289] Active Vessel is in atmosphere. Cannot save.
[LOG 15:37:00.484] Active Vessel is in atmosphere. Cannot save.
[LOG 15:37:30.635] Active Vessel is in atmosphere. Cannot save.
[LOG 15:38:00.854] Active Vessel is in atmosphere. Cannot save.
[LOG 15:38:20.611] [PlanetariumCamera]: Focus: Kerbin
[LOG 15:38:20.618] Maneuver Mode enabled
[LOG 15:38:31.007] Active Vessel is in atmosphere. Cannot save.
[LOG 15:39:01.171] Active Vessel is in atmosphere. Cannot save.
[LOG 15:39:24.332] Camera Mode: AUTO
[LOG 15:39:30.294] [PlanetariumCamera]: Focus: Kerbin
[LOG 15:39:30.301] Maneuver Mode enabled
[LOG 15:39:31.952] Active Vessel is in atmosphere. Cannot save.
[LOG 15:39:32.479] Camera Mode: AUTO
[LOG 15:40:02.139] Active Vessel is in atmosphere. Cannot save.
[LOG 15:40:32.282] Active Vessel is in atmosphere. Cannot save.
[LOG 15:41:02.544] Active Vessel is in atmosphere. Cannot save.
[LOG 15:41:15.360] deltaWing collided into Fuel Tank - relative velocity: 140.0589 - no impact momentum (no RB)
[LOG 15:41:15.361] deltaWing Exploded!! - blast awesomeness: 0.1
[LOG 15:41:15.377] [solarPanels5]: Deactivated
[LOG 15:41:15.382] [deltaWing]: Deactivated
[LOG 15:41:15.388] [01:17:23]: Delta Wing collided into Launch Pad.
[LOG 15:41:15.402] 1 explosions created.
[EXC 15:41:18.771] NullReferenceException
SpriteMesh.CreateMesh ()
SpriteMesh.get_mesh ()
SpriteRoot.Delete ()
SpriteBase.Delete ()
UIListItemContainer.Delete ()
UIScrollList.RemoveItem (Int32 index, Boolean destroy, Boolean doEasing)
UIScrollList.RemoveItem (IUIListObject item, Boolean destroy, Boolean doEasing)
UIScrollList.RemoveItem (IUIListObject item, Boolean destroy)
ApplicationLauncher.RemoveApplication (.ApplicationLauncherButton button)
ResourceDisplay.OnDestroy ()

This was the log from a space plane after reentry to Kerbin from a Kerbol orbit via Kerbin escape orbit and atmo braking, overshot KSC, turned and made a high retrograde in atmo approach intending to drop and turn, some 2000+m over KSC this happened again. For me it always seems to be small delta or delta wings, and it is always space planes possibly because the planes make horizontal approaches and I tend to use deltas. I AltF4d after the collision.

NB initial collision is between parts, delta wing and fuel tank see bold, no visible cause or explanation for that, just happens when coming close to KSC, but delta wing collision with launch pad happens after the delta wing has exploded and been deactivated. The launchpad was about 2 km away at the time.

Edit: sorry, I seem to have uploaded the wrong save file. I can't take down the last one, can I? I'll try to find the right one now.
Edit 2: alright, I really messed up. Had the save file that seemed to reproduce this bug though restarts, but I overwrote it and uploaded the one that came after. I don't have a copy anymore. If someone could delete my two messages, that would be great.
Sorry again to spam.

I will hazard a guess that your quicksave did reproduce this behaviour while in the same game session, but disappeared when you had restarted KSP? This is a characteristic of the problem, so any attempts to recreate it on other machines, or even on the same machine but different game sessions proves fruitless.

Your report does confirm that a variation of the original problem still exists, although we believed we had identified the root cause. I suspect that there is a trigger for this at some point during the flight, and some action or event is leaving the game in an indeterminate state. If we can establish a pattern of behaviour or sequence of events during the flight, we might be able to build a full reproduction for analysis.

I have seen this occur during a streamed video, but unfortunately it was only a clip of the actual collision, not what happened prior.

Would you care to outline your flight prior to this happening? Regardless, a copy of your log for the session would be of help too.

Just had this bug 20 mins ago, (I strongly suppose its this bug, I didnt even know that the mission log could be viewed outside crashes) I was descending with my SSTO towards the runway, then roughly 15-18 km away at about 4km ASL my wings flew off. I quicksaved just 20 seconds before, so I got to repeat it a good 7-8 times before ALT-F4 in the hopes of restarting KSP will save my previous 1-1,5 hours work and crew from dying.
Reloading solved the issue and landed without problem afterwards.

The craft is a LF SSTO, with 2 delta wings on the back, winglets on the front, mk2 cockpit, mk2 crew cabin.

It felt like the wing loss was bound to a timer, the plane was gliding stable @4km, 70m/s with about 10° descent after quickload, and I tried different maneuvers, starting engines to accelerate, increasing descent, dropping the nose and starting engines, all my tries ended with the wings blowing off after about the same time after load.

So in the hopes of helping track down the bug heres my mission profile:

Takeoff, ~6min burn to orbit,

Rescued a Kelbal from LKO, (multiple orbit changes, time warps),

then docked with refueling station (again multiple orbit changes, time warps),

refueled, then undocked and went for the Mun

after setting the maneuver node and warping to it, quicksaved and did the burn to Mun encounter,
time warped, then before insertion burn quickloaded to before Mun burn, and did it again,

rescued a Kelbal from Mun orbit, did a brake to get "suborbital orbit on moon" for one of the passengers, recircularized the orbit, then left Mun SOI to transfer to Minmus orbit

did a Minmus encounter, braked to orbit around Minmus for other passenger, then immediately left Minmus SOI to return to Kerbin.

To return I burned till 20km periapsis, quicksaved and timewarped to pe with KAC,
did the entry, then after reaching safe altitude and speed (700 m/s @20km), noticed I overshot KSC, so quickloaded back to ap, changed pe to 40km, to try and circularize the orbit so I could land at KSC.

The aerobraking went good, reduced the ap to 270km and I didnt need any maneuvers to get a prefect KSC landing trajectory, so I started the entry and got to the disappearing wings state in the end.

So there were lots of time warping, both wth auto timewarp and with Kerbal Alarm Clock - there was even a maximum time acceleration warp before reaching Minmus, and around the Mun i got the "cannot click the orbit to set maneuver node " bug, so switched to the Space Center and back to the craft to fix it.

Thats about it.

I'm having this problem regularly, recently in my Career save. I found it extremely hard to reproduce but it happens all the time when I don't try and just play - the problem is that it takes a long time and there is a lot happening. Typical scenario where it happens to me: undock my tourist bus from Minmus station, fly it to Kerbin, aerobrake, rendezvous and dock with station in Kerbin orbit. Transfer tourists to SSTO docked to the station, undock the SSTO, deorbit it and land on Runway - 50% of the time individual wing parts start crashing into launchpad or even other KSC buildings (had this happen with VAB recently) on approach to the runway. The launchpad can even get destroyed by it and I need to repair it afterwards.

Restart of the game and restore from quicksave gets rid of the problem, repeated approach is then fine.

My theory is that this problem is somehow related to docking. My tourist transport consists of two parts (tug and habitable module) and I keep to dock and redock them in various ways. The game seems to have issues in complex docking scenarios (letters stand for different ships, "-" is docking connection:

A + B -> A-B
A-B + C -> A-B-C
A-B-C -> A + B-C
D + B-C -> D-B-C
D-B-C -> D-B + C

Ship names get regularly lost in this process, I need to rename them all the time if I want them to keep their names. I'm planning to report the names issue separately sometime when I get over to make a reproducible scenario.

This whole issue might be also another side effect of #6010

Have not been able to duplicate this bug in 1.1.2.