1.1.1 phantom force?

[Brainlord Mesomorph]

Anyone getting phantom force?

twice now i'm in orbit trying to plot a node, and I notice Pe is moving toward my current pos and Ap is moving away!

I quickly turn off throttle and RCS, nothing helps

And then I have to Alt-F4 out of  the game to keep it from ruining my save.

(mods KAC and HyperEdit only)

(it might be me, I might have *something* on...)

Edited April 30, 2016 by Brainlord Mesomorph

[Agent K]

Confirming phantom force.

I noticed yesterday (with KSP 1.1.1) that in my old pre-1.0 save all my orbiting vessels seem to constantly slow down a bit. Ap and Pe decreasing around 0.1 m per second in Kerbin orbit and 0.1 m per 5 seconds in Duna orbit. Problem still there with 1.1.2 now. Turning on time warp makes Ap and Pe stable, turning time warp off makes both slowly decrease again.

I'm going to try some other saves now.

 

Installed mods: KER, Waypoint Manager, Kerbal Alarm Clock, KSP-AVC.

 

Edit: Effect doesn't seem to depend on vessel mass, it looks exactly the same with a 16 ton vessel and a 165 ton vessel. And I noticed that Ap and Pe values don't change by the same rate all the time. The closer the vessel gets to either Ap or Pe, the faster I see the value for the closer point decrease while the other one goes down slower.

Edit #2: Same problem when I start a new sandbox game and launch a small test rocket into stable orbit.

Edit #3: Uninstalled KSP, removed all remaining folders from install location, reinstalled KSP, no mods, same results. So it's either the game itself or my computer forgot how to compute. 

Edited April 30, 2016 by Agent K
Additional information.

[Shadowmage]

Just noticed a similar effect during dev testing of my mod; sent a small craft on a munar intercept trajectory, and could watch the PE of the mun intercept change.  This was more on the order of 1m/s/s.  After a short while it stabalized, and then started increasing.  Did note though that the ap/pe were flickering around far less and the orbit lines were less finicky; so there might have been some cleanup to that end of the code.. at least the display values part of things.

In prior versions (0.90, 1.0.X) I had similar occurrences, though the rate of change seemed to be tied to the gravitational pull of the planet and/or orbital speed;  things in orbit around minmus were very unstable and would eventually either decay and hit the surface or reach escape trajectory if left at normal time warp long enough.  Things in orbit around Kerbin, Jool, Tylo, Eve were much more stable and it would take hours for any noticeable alteration of their trajectory.

Seems likely that this all just comes down to floating-point precision; single-precision operations are merely not precise enough to calculate anything more than a few kilometers without rounding errors creeping in, and this is more than likely what we are seeing.  While at >1 time warp the vessel position is dictated by the on-rails calculations, moved along a pre-determined path; while at regular time the vessel is moved by physics calculations and subject to precision problems.

[steve_v]

12 minutes ago, Shadowmage said:

After a short while it stabalized, and then started increasing.

If it's an cyclical, rather than a steady acceleration, I suspect this might have something to do with it:

On 26/04/2016 at 11:53 AM, SQUAD said:

In 1.0.5 Nathan redid how a vessel’s center of mass was calculated. However, that had not been hooked up to the orbital calculations until now. Nathanael (NathanKell) has finally done so, improving the calculation of gravity so that orbits no longer flicker from vessel rotation. It does show that the PhysX integrator has some issues with velocity at orbital speed so the Apoapsis and Periapsis are not constant when off rails, but the behavior is far better than in 1.1 or 1.0.5.

On 27/04/2016 at 7:16 AM, NathanKell said:

as I mention in the dev note it _has_ more clearly exposed an integration issue from PhysX; orbital information does still change slightly frame to frame due to integrator instability. But the change is very smooth now (albeit still cyclical) and you'll at least know what orbit you're getting when you go on rails. And rotating the vessel actually increases orbital stability rather than decreasing it!

[Shadowmage]

Yep, that seems to explain it

The behaviour is certainly different than it was in 0.90 or 1.05; and the changes you pointed out would seem to explain those differences.  Still a bit dismayed that I can't get stable orbits unless I use time-warp... but I suppose that is what station-keeping is all about in KSP

 

[NathanKell]

The issue here can indeed be seen in 1.0.5 and 1.1 in a single part vessel (kerbal on EVA, say). I have gotten it down to only 6 meters/second change in Munar Pe right after the TMI burn, which is at least an order of magnitude better than 1.1 / 1.0.5.

[Warezcrawler]

I observe phantom forces too. When I send a rocket up.... Just about when I'm to exit the atmosphere my craft starts to accelerate and I loose all control. Log Exceptions occur .....

I didn't have this issue before 1.1.2. But it does make the game pretty much unplayable.... I thought it was my mods.... But based on Agent K's comment I don't think I will waste more time removing them one by one....

7 hours ago, Agent K said:

Installed mods: KER, Waypoint Manager, Kerbal Alarm Clock, KSP-AVC.

 

[Agent K]

5 minutes ago, Warezcrawler said:

But based on Agent K's comment I don't think I will waste more time removing them one by one....

As your problem seems to be much worse than mine you could still try without mods.

 

2 hours ago, NathanKell said:

The issue here can indeed be seen in 1.0.5 and 1.1 in a single part vessel (kerbal on EVA, say).

So I guess you are talking about something else than that slow and steady descent on orbits that should be considered stable.

Rocket made of 9 parts, 1.1.2 x64, orbiting Kerbin, Ap 630 km, Pe 118 km. Result after orbiting from Pe to Pe with SAS and RCS off: Ap 425 m lower, Pe 165 m lower.

I'm quite sure I never saw that before 1.0.

[Warezcrawler]

Ok... So I had an install with much less mods on it, so I migrated a craft over, added the missing mods for the craft, and tried again.... Still does it. I reach light speed in only a few minutes after takeoff.

Spoiler

DLL's in install

Stock assembly: Assembly-CSharp v0.0.0.0
ModuleManager.2.6.24 v2.6.24.0
AutoRove v1.0.0.0
EditorExtensionsRedux v2.12.5962.33242
MiniAVC v1.0.3.0
GTI_Utilities v1.0.25.0
MightyPirate v0.6.224.0 / v0.6.224
InterstellarFuelSwitch v1.27.0.0 / v1.27.0
MiniAVC v1.0.3.1
Scale_Redist v1.0.0.0
KerbalEngineer v1.1.1.0
KerbalEngineer.Unity v1.0.0.0
MiniAVC v1.0.3.2
CLSInterfaces v1.0.0.0
ShipManifest v5.0.9.0
Stock assembly: KSPSteamCtrlr v0.0.1.33
Stock assembly: SaveUpgradePipeline.Scripts v1.0.0.2 / v1.0.0.21
Stock assembly: Steamworks.NET v8.0.0.0 / v8.0.0
WaypointManager v1.0.0.0 / v2.5.0

These are for recreating on KSP 1.1.2 install. I get the effect every time now..... 

MODs: KSP_PhantomForces_GameData.rar (all gamedata files, except for the squad ones)

Savegame: KSP_PhantomForces_Savegame_SandBox.rar (there is a craft in the savegame, which I basically just try to take to space)

Log file: KSP_PhantomForces_KSP.log

Highlights from log file....
 

Spoiler

[LOG 00:42:43.956] [F: 9734]: [00:00:00]: Liftoff!!
[LOG 00:42:53.201] Packing Kerbal Rescue 3 Debris for orbit
[LOG 00:42:53.218] Packing Kerbal Rescue 3 Debris for orbit
[LOG 00:42:53.218] Packing Kerbal Rescue 3 Debris for orbit
[LOG 00:42:53.219] Packing Kerbal Rescue 3 Debris for orbit
[LOG 00:43:07.400] Kerbal Rescue 3 Debris Unloaded
[LOG 00:43:07.401] Kerbal Rescue 3 Debris Unloaded
[LOG 00:43:07.401] Kerbal Rescue 3 Debris Unloaded
[LOG 00:43:07.402] Kerbal Rescue 3 Debris Unloaded
[LOG 00:43:11.005] [AsteroidSpawner]: No new objects this time. (Odds are 1:2)
[LOG 00:43:26.094] [AsteroidSpawner]: New object found near Kerbin: Ast. JYX-246!
[LOG 00:43:48.140] [F: 13553]: [00:01:03]: Separation of stage 5 confirmed
[LOG 00:43:48.162] [F: 13554]: [00:01:03]: TR-18A Stack Decoupler was heated by engine exhaust from LV-T45 "Swivel" Liquid Fuel Engine.
[LOG 00:43:48.312] [F: 13564]: [00:01:04]: TR-18A Stack Decoupler was heated by engine exhaust from LV-T45 "Swivel" Liquid Fuel Engine.
[LOG 00:44:11.443] [AsteroidSpawner]: No new objects this time. (Odds are 1:2)
[LOG 00:44:26.511] [AsteroidSpawner]: New object found near Kerbin: Ast. PAD-567!
[LOG 00:44:28.777] [F: 15969]: [00:01:44]: Probodobodyne OKTO exploded due to overheating.
[LOG 00:44:28.778] probeCoreOcto Exploded!! - blast awesomeness: 0
[LOG 00:44:28.782] [solarPanels5]: Deactivated
[LOG 00:44:28.784] [solarPanels5]: Deactivated
[LOG 00:44:28.785] [probeCoreOcto]: Deactivated
[LOG 00:44:28.799] 1 explosions created.
[LOG 00:44:29.309] [F: 16000]: [00:01:44]: Z-100 Rechargeable Battery Pack exploded due to overheating.
[LOG 00:44:29.310] batteryPack Exploded!! - blast awesomeness: 0.5
[LOG 00:44:29.310] [batteryPack]: Deactivated
[LOG 00:44:29.319] [Progress Node Complete]: RecordsSpeed
[LOG 00:44:29.335] 1 explosions created.
[LOG 00:44:29.544] [F: 16013]: [00:01:44]: Mk1 Command Pod exploded due to overheating.
[LOG 00:44:29.545] mk1pod Exploded!! - blast awesomeness: 0.5
[LOG 00:44:29.549] [mk1pod]: Deactivated
[LOG 00:44:29.571] 1 explosions created.
[LOG 00:44:29.578] [F: 16014]: [00:01:44]: Structural failure on linkage between LV-T45 "Swivel" Liquid Fuel Engine and FL-T800 Fuel Tank.
[LOG 00:44:29.581] [F: 16014]: [00:01:44]: Structural failure on linkage between FL-T800 Fuel Tank and FL-T400 Fuel Tank.
[LOG 00:44:29.583] [F: 16014]: [00:01:44]: Structural failure on linkage between FL-T400 Fuel Tank and TR-18A Stack Decoupler.
[LOG 00:44:29.585] [F: 16014]: [00:01:44]: Structural failure on linkage between TR-18A Stack Decoupler and LV-909 "Terrier" Liquid Fuel Engine.
[LOG 00:44:29.588] [F: 16014]: [00:01:44]: Structural failure on linkage between LV-909 "Terrier" Liquid Fuel Engine and FL-T800 Fuel Tank.
[LOG 00:44:29.597] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.598] [F: 16014]: fuelTank collided into fuelTank.long - relative velocity: 399.2697 - impact momentum: 1538.0
[LOG 00:44:29.598] fuelTank Exploded!! - blast awesomeness: 0.5
[LOG 00:44:29.599] [fuelTank]: Deactivated
[LOG 00:44:29.600] [F: 16014]: [00:01:44]: FL-T400 Fuel Tank collided into FL-T800 Fuel Tank.
[LOG 00:44:29.600] [F: 16014]: [00:01:44]: Structural failure on linkage between FL-T800 Fuel Tank and TR-18A Stack Decoupler.
[LOG 00:44:29.607] 1 explosions created.
[LOG 00:44:29.613] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.614] recalculating orbit for fuelTank.long: Kerbin
rPos: [NaN, NaN, NaN]   rVel: [NaN, NaN, NaN] |NaN|
[LOG 00:44:29.614] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.614] recalculated orbit for fuelTank.long: the Sun
rPos: [NaN, NaN, NaN]   rVel: [NaN, NaN, NaN] |NaN|
[LOG 00:44:29.616] [Progress Node Reached]: Escape
[LOG 00:44:29.616] [Progress Node Reached]: Kerbin
[LOG 00:44:29.616] [Progress Node Complete]: Escape
[LOG 00:44:29.617] [Progress Node Reached]: Flyby
[LOG 00:44:29.617] [Progress Node Reached]: Sun
[LOG 00:44:29.617] [Progress Node Complete]: Flyby
[LOG 00:44:29.624] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.641] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.659] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.692] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.708] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.725] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.742] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.758] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.792] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.808] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.825] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.842] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.859] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.892] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.909] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.925] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.942] E is NaN! tA: 3.14159265358979, e = NaN
[LOG 00:44:29.959] E is NaN! tA: 3.14159265358979, e = NaN

@NathanKell I really think we have a stock KSP bug here, but of cause this is not perfect proof, since the install is modded.... I removed all mods except SpaceY, Module Manager and surface lights, and I actually got the thing to space.... So it's probably mod related....

Does anyone have an idea of what can cause this?

Edited April 30, 2016 by Warezcrawler

[NathanKell]

Please test this in 1.1 and 1.0.5. Use a single part craft (like an EVA kerbal) and see what kind of orbital drift you get.

[Warezcrawler]

I found out the Interstellar fuel switch had a change in functionality where the drymass of the fuel tanks could end up being zero when the tank emptied. This apparently results in KSP going nuts...... Maybe it would be a good idea to handle such cases in the KSP engine, so that phantom forces does not come from zero mass parts.....

But of cause part should have mass, so that can fix the issue.

[sol_invictus]

I am experiencing phantom forces too on my game with KOs and RemoteTech, which makes some of my operations impossible I can't have a perfect circular orbit around the Mun, even worse around Minmus, preventing me from setting up stable communication networks 

[Mastikator]

I've had the same problems as others, phantom forces that break my ship apart. I've also seen multistage rockets where only the outer stages experience phantom forces. And quickly run away from me when I detach them. Because of this I am no longer able to launch anything into space anymore or keep focus on any space craft for more than a minute.

This did not occur at the beginning of my career that started in 1.1, only 1.1.2

Using long list of mods: Near future, interstellar, outer planet, extraplanetary launchpads, visual enhancements, tac lifesupport, magic smoke, scatterer, kis, kas, final frontier and everything that requires those mods.

[Dragonator]

I have the same problem, but only with a satellite with SCANsat in a polar orbit.