AeroBrakeMFD Trouble with Aerocapture

[spacekid1998]

BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 52159.1369957559
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01S
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01S
  MODE Cockpit
  FOV 60.00
END_CAMERA

BEGIN_HUD
  TYPE Surface
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target none
  Center GravityRef
  Data 0 1 1e-006 1 0 0 0 0 1 1 0 0
  MassLimit 1e+020
  CMode 0
  Config 1 1 1 1 0 0
  ExtMode 0
  Periapis none
  END 
  CorMFD V4
  Reference Mars
  Target Equator
  Source GL-01S
  ActiveProg 3 3
  DataA 1 3 0 0 0 0
  DataB 1 10 52159.13699575589 0 40000 4.264781442386184 0.3490658503988656 52159.2666042166 0
  DVProg 0 0 0 1
  AdvConf 0 0 1 0 0
  Guidance 0
  END 
  EjectMFD V5
  Reference Auto
  Data 0 1 3 0 1 52158.104144367 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Mars
  Target Olympus
  Source GL-01S
  DataA 0 0 120000 0.10821 0.366519 1 1 52158.104144367 52158.104144367 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source 
  Data 0 1 1 3 0 1 51982.66883972571 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 0
  CF1_DataB 52158.104144367 10 120000 2 20 150000
  CF1_SecTgt 
  mfdShare 1
  mfdProgram 2
END_MFD

BEGIN_MFD Right
  TYPE Orbit
  PROJ Frame
  FRAME Ecliptic
  ALT
  REF Mars
END_MFD


BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Sun
  RPOS -213396150067183.34 -3912374576394477.50 1030970279894384.60
  RVEL -14116833.021 -258996134.454 68248694.028
  AROT 110.00 -10.00 80.00
  PRPLEVEL 0:1.000
  IDS 0:588 100 1:586 100 2:584 100 3:582 100 4:580 100
  NAVFREQ 0 0
  XPDR 466
END
Mir
  STATUS Orbiting Sun
  RPOS -4294220007735437.50 -196489773723686.00 2505185922709334.00
  RVEL -284264178.212 -13007469.152 165840616.063
  AROT 0.00 -45.00 90.00
  IDS 0:540 100 1:542 100 2:544 100
  XPDR 482
END
Luna-OB1:Wheel
  STATUS Orbiting Sun
  RPOS 145748958974.76 -5593528589.50 -56179159182.95
  RVEL 9864.227 3442.140 26778.314
  AROT 0.00 0.00 145.37
  VROT 0.00 0.00 10.00
  IDS 0:560 100 1:564 100
  XPDR 494
END
GL-01S:DG-S
  STATUS Orbiting Mars
  RPOS -3239111.27 -6038510.89 50896253.99
  RVEL -25.484 895.180 -4864.454
  AROT 81.09 46.98 -94.43
  RCSMODE 2
  PRPLEVEL 0:0.165 1:0.957 2:0.981
  THLEVEL 20:1.000 21:1.000
  NAVFREQ 94 524 84 114
  XPDR 0
  PSNGR 2 3 4
  TANKCONFIG 1
END
SH-03:ShuttleA
  STATUS Landed Earth
  BASE Habana:4
  POS -82.3982414 23.0005396
  HEADING 70.00
  PRPLEVEL 0:1.000 1:1.000
  NAVFREQ 0 0
  XPDR 0
  PODANGLE 0.0000 0.0000
  DOCKSTATE 0 0.0000
  AIRLOCK 0 0.0000
  GEAR 0 0.0000
  PAYLOAD MASS 0.0 0
END
PB-01:ShuttlePB
  STATUS Landed Earth
  BASE Habana:1
  POS -82.4000000 22.9994604
  HEADING 22.00
  PRPLEVEL 0:1.000
  NAVFREQ 0 0
END
GL-02:DeltaGlider
  STATUS Landed Mars
  BASE Olympus:3
  POS -135.4300000 12.7366196
  HEADING 0.00
  PRPLEVEL 0:1.000 1:1.000
  NAVFREQ 0 0 0 0
  XPDR 0
  GEAR 1 1.0000
END
SH-01:ShuttleA
  STATUS Landed Moon
  BASE Brighton Beach:1
  POS -33.4375000 41.1184067
  HEADING 0.00
  PRPLEVEL 0:1.000 1:1.000
  NAVFREQ 0 0
  XPDR 0
  PODANGLE 0.0000 0.0000
  DOCKSTATE 0 0.0000
  AIRLOCK 0 0.0000
  GEAR 0 0.0000
  PAYLOAD MASS 0.0 0
END
END_SHIPS

in this scenario i am at the edge of Mars SOI with a PEA of 40km and EqI 20*. how can i set up aerobrake mfd for an aerocapture, the only tutorial i could find is in regards to re-entry for landing? And also how did you arrive at this value of 40km for mars? What if I want to aerocapture on Earth or venus obviously these have different optimal PEA

 

[Rtyh-12]

You get at this value through trial and error. I recommend saving your scenario when you are high enough to easily be able to change PeA, but still quite low. Then just experiment.

 

[spacekid1998]

ok and what is the procedure for aerocapture using aerobrake mfd

 

[insanity]

It's all a bit seat-of-your pants trial and error stuff. For mars, I go inverted, base aligned, with a PeA of 40km. Then it's all about watching your trajectory in aerobrake and adjusting your AoA so that you slow down enough to get your next orbit with a low enough ApA so you can easily come down on the next pass. Once your ApA is acceptable, I roll right-side up, drift outside of the atmosphere, and then make sure I'm still aligned for the next pass and then it's just a powered descent as usual.

Or you could be riskier and go for a complete aerobrake where you get down to the base on your first pass. I often try to aim for my initial contact PeA to just pass the base then spend an orbit of the planet braking and finally landing. This requires watching aerobrake, patience, and practice.

 

[HarvesteR]

I've found that one of the best ways to use Aerobrake is by having attitudeMFD open right next to it.

Use attitudeMFD to fine tune your entry attitude... once dynamic pressure starts to build up, attitude will start to struggle keeping the craft stable, so you can help it with elevator trim and a little manual input.

Do this while watching AeroBrakeMFD's trajectory, and try to keep it on target. It's much easier to do manual trimmings and corrections when you have attitudeMFD holding it steady for you... you just apply correction input.... if you came in completely manual it would be a white knuckle ride all the way through :sos: (you do have to fight AttitudeMFD a little bit, but it's there to make sure you always 'return to center')

Each planet and moon has it's own particular quirks for these things... the above will work well for Earth, and possibly for Mars too... haven't tried it on venus... as Insanity said, it's a matter of trying it various times and seeing what works and what doesn't.

Cheers

 

[Wishbone]

Incidentally, Aerobrake also comes with its own autopilot. One has to tweak .ld files though, to damp oscillations (the default settings aren't stable).

 

[Grover]

I prefer to stay in the atmosphere, you dont even need an accurate approach, just sink into the atmosphere, inverted, then hold your altitude at a given altitude and stay there using your wing lift to stay low, once youve slowed down, just roll upright and go back to space with a low orbit, align with the base then enter as normal

If youre in an xr or dgIV you need to watch the hull temperatures, and it takes a lot of patience, even for earths atmosphere, but its not too hard to do.

Good luck

 

[Tommy]

Right now the XR series are the only vessels that can perform a high AoA inverted re-entry with any ease - especially the latest builds (the AoA autopilot now supports inverted flight).

In any other vessel, I use a low AoA, maintained by elevator trim only. I don't worry about base alignment before re-entry since you'll have plenty of cross range and can make it to any target. I engage full "upward" trim, enter at 90 degrees bank, and adjust the bank angle as needed to maintain my target altitude. Since this is usually less than 180 degrees (fully inverted), this will allow me to align with the target base - once aligned I lower the trim so I can fly fully inverted (thus maintaining base alignment and altitude) until suborbital velocity is reached - then roll upright and continue as in a normal re-entry.

Low AoA re-entries take longer than high AoA, but are easier to perform on most vessels, and provide virtually unlimited crossrange. I can reach any target base, regardless of my initial re-entry point and direction.