IMFD Question about IMFD Surface Launch Program

Marijn

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Hello all,

I would like some help with IMFD's Surface Launch Program.

The trajectory I am trying to set up comes from NASA's trajectory browser. It's a 192-day trip to Mars. Departe MJD (TMI burn) is 59064.5. Arrival MJD is 59256.5.

In the left MFD, I select the Mars and set these MJD's up in the Course Target Intercept Program. The right MFD is slaved to the left (OpMode Shared ID=0) and the Surface Launch Program is openend and set to OpMode=Course.

The Surface Launch Program has a MJD value in dark-green which can be set. However, I do not see anything changing after modifying this value. So my first question is: What's the purpose of the MJD setting in dark-green?

Then my main question:

I want to calculate the optimal MJD for a launch from Cape Canaveral. I don't care about the launch heading since it is given by the Surface Launch Program, but I do want to calculate the MJD so I can use it to determine the appropriate MJD for the scenario start. I am interested in both optimizing the delta-v as the flight duration if there happens to be a difference between these.

I noticed that when I launch the scenario 1 day prior, so at MJD 59063.5, two solutions (Ein < 1) can be found. The first one means that a lot of time has to be spend in orbit waiting until it is time to depart at 59064.5. The second solution is at 59064.229. So I think this is the value I am looking for.

Any help or suggestions on how this value can be calculated?

Thnx
 

boogabooga

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Hello all,

In the left MFD, I select the Mars and set these MJD's up in the Course Target Intercept Program. The right MFD is slaved to the left (OpMode Shared ID=0) and the Surface Launch Program is openend and set to OpMode=Course.

The Surface Launch Program has a MJD value in dark-green which can be set. However, I do not see anything changing after modifying this value. So my first question is: What's the purpose of the MJD setting in dark-green?
It has no purpose when OpMode=Course, hence dark green and not bright green. It is just a leftover of other modes that do use it.

Then my main question:

I want to calculate the optimal MJD for a launch from Cape Canaveral. I don't care about the launch heading since it is given by the Surface Launch Program, but I do want to calculate the MJD so I can use it to determine the appropriate MJD for the scenario start. I am interested in both optimizing the delta-v as the flight duration if there happens to be a difference between these.
Optimizing the delta-v - for the whole trip or for the launch phase? If the former, don't forget that the Course program has a Tej, but anytime around 59064.5 should work fine. If the latter, launch when the lime green "time" in Surface Launch is 0.

I noticed that when I launch the scenario 1 day prior, so at MJD 59063.5, two solutions (Ein < 1) can be found. The first one means that a lot of time has to be spend in orbit waiting until it is time to depart at 59064.5. The second solution is at 59064.229. So I think this is the value I am looking for.

Any help or suggestions on how this value can be calculated?
This does not make any sense. What do you mean two solutions? To what?

There are an infinite number of solutions; you can launch anytime as long as you fly to the correct heading. Ein will then decrease toward 0 as you reach orbit.
 

IronRain

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This does not make any sense. What do you mean two solutions? To what?
.
marijn said:
I noticed that when I launch the scenario 1 day prior, so at MJD 59063.5, two solutions (Ein < 1) can be found.
IMFD shows the optimal launch time which is when Ein is <1, as Marijn stated. So if you set the scenario 1 day before Tej, you get 2 optimal launch opportunities. I think the question is how one can predict/calculate when the optimal launch time closest to Tej is instead of guessing if/when there is a next opportunity.
 

Marijn

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I think the question is how one can predict/calculate when the optimal launch time closest to Tej is instead of guessing if/when there is a next opportunity.
That's indeed what I meant. I am working on a piece of software which transforms a trajectory from NASA's trajectory browser into a ready-to-fly Orbiter scenario.

The first node of the trajectory offered by NASA starts just after the TMI burn (the 59064.5 MJD). But I want to start these scenario's from a landed state at the runway on KSC.

Therefore my question, how can one calculate the MJD closest to 59064.5 which is required to start the scenario right at the moment where Ein equals 1.00 on the way down?
 
Last edited:

boogabooga

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For those of you thinking that EIn is the relevant criterion here, try to use the surface launch in either of these scenarios without altering the valid course plan:

Code:
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51983.5694361846
  Help Default\Checklists\Checklist1,Checklist1
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01
  MODE Cockpit
  FOV 50.00
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 0 0 0
  MassLimit 1e+020
  CMode 0
  Config 1 1 1 1 0 0
  ExtMode 0
  Periapis none
  END 
  CorMFD V4
  Reference Sun
  Target Mars
  Source Earth
  ActiveProg 1 1
  DataA 0 3 0 0 0 0
  DataB 1 100 51993.10705701826 0 0 5.692570592536612 0 52178.83489098255 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 51983.5620191133 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source GL-01
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.5620191133 51983.56367867826 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source GL-01
  Data 0 1 1 3 0 0 51983.5620191133 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 1 1 51983.5694347009
  END 
  CF1_DataA 0 0
  CF1_DataB 0 10 120000 2 20 200000
  CF1_SecTgt 
  mfdShare -1
  mfdProgram 2
END_MFD

BEGIN_MFD Right
  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 0 0 0
  MassLimit 1e+020
  CMode 0
  Config 1 1 1 1 0 0
  ExtMode 0
  Periapis none
  END 
  CorMFD V4
  Reference Sun
  Target Mars
  Source Earth
  ActiveProg 1 1
  DataA 0 3 0 0 0 0
  DataB 1 100 51993.10705701826 0 0 5.692570592536612 0 52178.83489098255 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 51983.5620191133 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source GL-01
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.5620191133 51983.56367867826 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source GL-01
  Data 0 1 1 3 0 0 51983.5620191133 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 1 1 51983.5694347009
  END 
  CF1_DataA 0 0
  CF1_DataB 0 10 120000 2 20 200000
  CF1_SecTgt 
  mfdShare 0
  mfdProgram 7
END_MFD

BEGIN_PANEL
END_PANEL

BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  RPOS 6613216.30 -394169.46 -1171026.75
  RVEL -70.460 -7410.149 2103.578
  AROT 112.39 -22.13 79.13
  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 6181270.01 -150625.82 -2489570.80
  RVEL 2889.965 442.358 7164.192
  AROT 0.26 -42.43 90.20
  AFCMODE 7
  IDS 0:540 100 1:542 100 2:544 100
  XPDR 482
END
Luna-OB1:Wheel
  STATUS Orbiting Moon
  RPOS -1616629.35 -1549395.59 228.27
  RVEL 1023.862 -1068.301 0.197
  AROT -0.00 -0.00 23.38
  VROT -0.00 -0.00 10.00
  AFCMODE 7
  IDS 0:560 100 1:564 100
  XPDR 494
END
GL-01:DeltaGlider
  STATUS Landed Earth
  POS -80.6825040 28.5968040
  HEADING 330.01
  RCSMODE 0
  AFCMODE 7
  PRPLEVEL 0:0.995000 1:1.000000
  NAVFREQ 94 524 84 114
  XPDR 0
  GEAR 1 1.0000
  AAP 0:0 0:0 0:0
END
SH-03:ShuttleA
  STATUS Landed Earth
  BASE Habana:4
  POS -82.3982414 23.0005396
  HEADING 70.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  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
  AFCMODE 7
  PRPLEVEL 0:1.000000
  NAVFREQ 0 0
END
GL-02:DeltaGlider
  STATUS Landed Mars
  BASE Olympus:3
  POS -135.4300000 12.7366196
  HEADING 0.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  NAVFREQ 0 0 0 0
  XPDR 0
  GEAR 1 1.0000
  AAP 0:0 0:0 0:0
END
SH-01:ShuttleA
  STATUS Landed Moon
  BASE Brighton Beach:1
  POS -33.4375001 41.1184067
  HEADING 0.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  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

BEGIN_ExtMFD
END

BEGIN_SpaceNetwork
END

Code:
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51983.2857184602
  Help Default\Checklists\Checklist1,Checklist1
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01
  MODE Cockpit
  FOV 50.00
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 0 0 0
  MassLimit 1e+020
  CMode 0
  Config 1 1 1 1 0 0
  ExtMode 0
  Periapis none
  END 
  CorMFD V4
  Reference Sun
  Target Mars
  Source Earth
  ActiveProg 1 1
  DataA 0 3 0 0 0 0
  DataB 1 100 51983.60420710505 0 0 0.3161312147004782 0 52261.71004613477 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 51983.56215828226 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source GL-01
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.56215828226 51983.56373822903 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source GL-01
  Data 0 1 1 3 0 0 51983.56215828226 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 1 1 51983.5639988491
  END 
  CF1_DataA 0 0
  CF1_DataB 0 10 120000 2 20 200000
  CF1_SecTgt 
  mfdShare -1
  mfdProgram 2
END_MFD

BEGIN_MFD Right
  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 0 0 0
  MassLimit 1e+020
  CMode 0
  Config 1 1 1 1 0 0
  ExtMode 0
  Periapis none
  END 
  CorMFD V4
  Reference Sun
  Target Mars
  Source Earth
  ActiveProg 1 1
  DataA 0 3 0 0 0 0
  DataB 1 100 51983.60420710505 0 0 0.3161312147004782 0 52261.71004613477 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 51983.56215828226 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source GL-01
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.56215828226 51983.56373822903 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source GL-01
  Data 0 1 1 3 0 0 51983.56215828226 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 1 1 51983.5639988491
  END 
  CF1_DataA 0 0
  CF1_DataB 0 10 120000 2 20 200000
  CF1_SecTgt 
  mfdShare 0
  mfdProgram 7
END_MFD

BEGIN_PANEL
END_PANEL

BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  RPOS -6349436.30 2187189.34 613907.09
  RVEL 2177.646 6970.428 -2389.308
  AROT 110.25 -11.37 79.95
  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 -5830723.10 197599.42 3246145.91
  RVEL -3763.592 -414.134 -6732.704
  AROT 0.06 -44.50 90.02
  AFCMODE 7
  IDS 0:540 100 1:542 100 2:544 100
  XPDR 482
END
Luna-OB1:Wheel
  STATUS Orbiting Moon
  RPOS 2155677.79 606384.37 -58.41
  RVEL -400.662 1424.361 -0.247
  AROT -0.00 -0.00 -73.30
  VROT -0.00 0.00 10.00
  AFCMODE 7
  IDS 0:560 100 1:564 100
  XPDR 494
END
GL-01:DeltaGlider
  STATUS Landed Earth
  POS -80.6825040 -0.0000000
  HEADING 330.01
  RCSMODE 0
  AFCMODE 7
  PRPLEVEL 0:0.995000 1:1.000000
  NAVFREQ 94 524 84 114
  XPDR 0
  GEAR 1 1.0000
  AAP 0:0 0:0 0:0
END
SH-03:ShuttleA
  STATUS Landed Earth
  BASE Habana:4
  POS -82.3982414 23.0005396
  HEADING 70.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  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
  AFCMODE 7
  PRPLEVEL 0:1.000000
  NAVFREQ 0 0
END
GL-02:DeltaGlider
  STATUS Landed Mars
  BASE Olympus:3
  POS -135.4300000 12.7366196
  HEADING 0.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  NAVFREQ 0 0 0 0
  XPDR 0
  GEAR 1 1.0000
  AAP 0:0 0:0 0:0
END
SH-01:ShuttleA
  STATUS Landed Moon
  BASE Brighton Beach:1
  POS -33.4375000 41.1184067
  HEADING 0.00
  AFCMODE 7
  PRPLEVEL 0:1.000000 1:1.000000
  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

BEGIN_ExtMFD
END

BEGIN_SpaceNetwork
END
EIn is an idea related to your orbit. On the ground, you have a pseudo-orbit and surface launch thinks that you are heading East only because of the Earth's rotation. So EIn tends toward zero as the required launch heading tends toward 90 degrees. However, valid plans exist that do not allow for 90 degree launches.

Some reading:
http://www.braeunig.us/space/orbmech.htm#hyperbolic

Basically, what surface launch is doing is calculating the point in space that will serve as the periapsis of your hyperbolic escape trajectory and calculating an orbit that includes both your current coordinates and that point within one full revolution.
 

Marijn

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For those of you thinking that EIn is the relevant criterion here, try to use the surface launch in either of these scenarios without altering the valid course plan
I had a go with the first scenario. Ein does not seem to drop below 30 degrees. Surface launch keeps displaying 'bad plane' at all times.

So your point is that Ein can be quite high, am I right?

This scenario starts 10 days prior to the eject date. I am not sure whether this is intentionally, but I want my scenario's to start als close as possible to the eject date so the amount of required time compression is minimized.
 

IronRain

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What I tend to do is:
  1. Start scenario at ejection time;
  2. Go back in time to the first possible launch time.

It's not a calculation, but it kind of works
 

boogabooga

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So your point is that Ein can be quite high, am I right?
No, my point is what I said that my point is, that EIn has no real meaning until you are in an actual orbit. Now try launching to the correct heading and watch what happens to EIn along the way.

This scenario starts 10 days prior to the eject date. I am not sure whether this is intentionally, but I want my scenario's to start als close as possible to the eject date so the amount of required time compression is minimized.
It's to show that at no point in time leading up to the eject date will EIn reach zero while you are on the ground.

Now, do you understand why this is the case?
 

Marijn

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Now, do you understand why this is the case?
Not at this time. But I only had a quick look at work. I will put some thought to it later when I am home and give the answer if I can. I expect the latitude of KSC to have part in this.
 

Marijn

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Now, do you understand why this is the case?
I can't really figure it out. It's a bit of a guess. But I think the date of the scenario's you gave and therefore the specific configuration of the solar system is not the ideal launchwindow for Mars.

So the velocity you get from the rotation of the earth is kind of misaligned with the final eject trajectory. Something like that.

I appreciate it if you would explain it.
 

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You are trying to get from your launch point to the point that will serve as the periapsis of your hyperbolic escape trajectory. If your final sun-centric orbit will be inclined with respect to the ecliptic, then that hyperbolic periasis point will need to be north or south of the ecliptic plane. If the latitude of the hyperbolic periapsis point is larger than your launch location latitude, you won't be able to get to it with a 90 degree heading. And the 90 degree launch is the only special case in which EIn will decrease to zero if you are still on the ground, because your "orbital plane" does not change through the launch phase.
 

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I believe so, but I would have to study that site closer to be sure.

It's a similar idea, anyway.
 
Last edited:
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