Flight Question Stuck RCS Thruster: A woeful trip from Venus

[DelRioPilot]

I've been posting a lot of problems here lately :lol:

This one was the most annoying though, because I haven't the faintest clue what could have caused it.

I did a flawless trip from Earth to Venus orbit in a DGIV, deployed a probe, and returned to Earth orbit just fine.

Did reentry almost okay. By the time I reached the Florida west coast, I realized I wouldn't have enough energy to glide to the runway. So I deactivated the reentry autopilot and throttled up to extend my flight to KSC.

However, I soon realized that I couldn't control pitch! It was almost as if the DGIV was still operated the reentry autopilot, and the RCS thrusters were fighting against me. Realizing I couldn't fly it myself, I activated the hover autopilot to attempt a landing on the landing pad. I literally got to within 30 feet of the landing pad, only for the DGIV RCS thrusters to pitch me up violently, and stall the craft into the ground.

I couldn't help but laugh afterwards. I had just delivered a craft from a little point on Earth to Venus and back, only to die right on the landing pad. Better luck next time I guess, but is there any reason the RCS thrusters were fighting against me? No autopilot commands were running.

 

[Staiduk]

It seems to me an autopilot program you might not have been aware of was still active - while the DG-IV is extremlely complex some of its complexities can bite if you're not very careful. There is no reason at all that the RCS thrusters should fire spontaneously; perhaps there was an AP program you initiated earlier in the flight but didn't cancel? Orbiter's autopilot processing is extremely literal; you might have fallen victim to that.

Nevertheless - good work! Flying a recon and science mission to Venus in no mean feat; though you crashed you flew a very good mission until that point!

Cheers!

 

[DelRioPilot]

Thanks for the info! Yes, that very well could have been what happened.

I loaded the last quick-save, and it was still causing me problems. But this time I turned off the RCS valve, and switched it back on. Somehow, this seemed to have solved the problem. I guess at least now, if it happens again, there's a work around.

 

[garyw]

Can you post the scenario where the RCS system was firing?

 

[DelRioPilot]

This is the scenario info from the latest quicksave:

BEGIN_DESC
Orbiter saved state at T = 26170947
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 83012.5732554507
END_ENVIRONMENT

BEGIN_FOCUS
  Ship DGIV-VENUS01
END_FOCUS

BEGIN_CAMERA
  TARGET DGIV-VENUS01
  MODE Cockpit
  FOV 50.00
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE Surface
  SPDMODE 1
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE GPC MFD
  ILOAD 0
  MODE 3
  SITE 1
  RUNWAY 0
  HAC 0
  MET 26170945
END_MFD

BEGIN_MFD 3
  TYPE Map
  REF Earth
  OTARGET ISS
  BTARGET Cape Canaveral
  ZOOM 2
  DISP 1711
END_MFD

BEGIN_MFD 4
  TYPE User
  MODE AeroBrakeMFD
  Reference Earth
  Data 0 1.000000 1 0 0 0
  Target cape_canaveral
  LonLat -1.408044 0.497782 1
  AoA 1 0.010077
  Bank 0 0.000000
END_MFD

BEGIN_PANEL
END_PANEL

BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Sun
  RPOS 297717544458.24 24768700632.12 225888445626.78
  RVEL -2185.826 -149.146 16815.505
  AROT 67.97 15.53 -122.65
  VROT -0.17 -0.06 0.04
  AFCMODE 7
  PRPLEVEL 0:1.000000
  IDS 0:588 100 1:586 100 2:584 100 3:582 100 4:580 100
  NAVFREQ 0 0
  XPDR 466
  O2_TANK 100.00
  FOOD_TANK 100.00
  CFG_MONTH_O2 6.00
  CFG_MONTH_FOOD 6.00
  UCGO @@0,1,0,0,@@1,1,0,0,@@2,1,0,0,@@3,1,0,0,@@4,1,0,0,@@5,1,0,0,@@6,1,0,0,@@7,1,0,0,
END
Mir:Mir
  STATUS Orbiting Earth
  RPOS -3037977.12 4381918.39 -3996588.73
  RVEL 6924.426 3029.179 -1867.670
  AROT 132.12 1.08 -134.07
  VROT 0.01 -0.19 -0.08
  AFCMODE 7
  IDS 0:540 100 1:542 100 2:544 100
  XPDR 482
END
Luna-OB1:Wheel
  STATUS Orbiting Moon
  RPOS -2817774.13 192140.03 2752.28
  RVEL -67.405 -1321.400 13.898
  AROT 0.48 -0.39 64.67
  VROT 0.00 0.00 10.00
  AFCMODE 7
  IDS 0:560 100 1:564 100
  XPDR 494
END
DGIV-VENUS01:DeltagliderIV
  STATUS Orbiting Earth
  RPOS -3439282.90 614879.49 -5429955.87
  RVEL 3246.007 7097.700 -952.408
  AROT 131.79 5.70 -39.67
  VROT 0.16 -0.00 0.00
  AFCMODE 6
  PRPLEVEL 0:0.345226 1:0.711640 2:0.983333
  THLEVEL 5:0.317924 6:0.317924 11:0.000027 12:0.000027 15:0.000054 16:0.000054
  IDS 0:45 100
  NAVFREQ 0 0
  XPDR 0
  ;-------------------------- Skin parameters must contain directory name of skin (without space) 
  MeshSkin spacetech
  ;-------------------------- Cargo payload must contain name of config file or "none".(see doc) 
  CargoPayload none
  NOSECONE 0 0.00
  GEAR 0 0.00
  AllDoorsState 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 0 0 0.00
  But1Cockpit 0 0 0 2 2 2 0 2 2 2 2 2 2 2 2 1 1 0 0 1 1 5
  But2Cockpit 0 0 0 0 0 0 0 0 2 2 2 2 2 0 50 0 0 0 0 0 0 0
  TransEffect 0
  LifeBut1State 0 2 1 2 1 2 2 2 2 2 2 2 2 0 0
  LevelBatt 100.0000
  Emergency_power 10000.0000
  VoltageStartBus 0.0000
  VoltageGen1 96.2800
  VoltageGen2 96.2800
  VoltageGenBus 96.0000
  O2tankALevel 9.2171
  N2tankALevel 100.0000
  O2tankBLevel 100.0000
  N2tankBLevel 100.0000
  CabinO2Level 21.3806
  CabinCO2Level 600.0000
  CabinTempLevel 21.9950
  CabinPressure 14.7000
  CabinMoistLevel 36.0000
  CabinDustLevel 0.0001
  CabinO2Setting 21.3935
  CabinTempSetting 21.9950
  CabinPressSetting 14.7000
  AntennaTarget Venus
  O2ConsumptionSetting 5
  FuelConsumptionSetting 3
  MainenginePower 1
  ;------------------Crew parameters  UMMUCREW Function-Name-Age-CardiacPulse-WeightKg (fonction of Pilot must be: Capt) 
  NoOneOnBoard 0
  NoPilotOnBoard 0
  UMMUCREW Capt-Mike_Speedo-41-78-79
  UMMUCREW Clim-Phillip_LeDux-46-68-79
  UMMUCREW Spe-Christian_Stewart-29-78-75
  UMMUCREW Spe-Roger_King-26-77-66
  UMMUCREW Eng-Frank_Turno-51-74-66
  FailGearFailure 0
  FailGearCollapse 0
  FailLeftMainEngine 0
  FailRightMainEngine 0
  FailHoverEngine 0
  FailRcs 0
  FailSurfaceControl 0
  FailComputer 0
  FailComputerBlueScreen 0
  FailAutopilot 0
  FailExtRadiator 0
  FailAirbrake 0
  FailNoseCone 0
  FailCanopy 0
  FailAntenna 0
  FailLeftTurbo 0
  FailRightTurbo 0
  FailCargoDoor 0
  SpacesuitTimer 0
  UCGO @@0,1,0,0,@@1,1,0,0,@@2,1,0,0,@@3,1,0,0,
END
CRG-00:DGIVMTKSSAT
  STATUS Orbiting Venus
  RPOS 5469130.28 -199364.94 3420320.72
  RVEL -3767.286 -411.884 5998.373
  AROT -30.89 28.99 -104.10
  VROT 0.06 0.00 -0.02
  AFCMODE 7
  NAVFREQ 0 0
  PowerUpStep 6
END
END_SHIPS

BEGIN_ExtMFD
END

 

[DelRioPilot]

Actually, I figured out the real reason the RCS was fighting against me.

Resetting the RCS valve didn't solve anything (I thought it solved the issue at first, but I was wrong). It actually turns out I had my AeroBrake MFD set to hold my AOA during the entire entry and landing phase... doh!

 

[Staiduk]

(Chuckle) Hence the benefit of checklists...

Dunn how many times One of the many MFD's which incorporate autopilots have tried to kill me over the years. I got into the habit of recording every manoeuver during a flight and constructing checklists for all major evolutions while in space - a habit I have to thank my r/l flying experience for. Saved my virtual life a few times, I must say.
Cheers!