IMFD Changing Burn Guidance Mode in IMFD

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Snaps2010

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So recently I've been trying to set up a Mars Mission but I've been having some problems with the TMI Burn. I've managed to do it with Trans X but due to its lack of an autopilot there is plenty of human error and i used up to much fuel to be able to return to earth. So i decided try IMFD because it had an autopilot but when I turn on the auto burn function it only works for a short wile before stopping the burn and leaving me still in earth orbit. I locked in the manual for IMFD and it seems that the problem is that the Burn Guidance Mode is set to Realtime when when it should be set to Off-Axis. When I look at IMFD in-game the Burn Guidance Mode option is grayed and i cant change it. I looked in the manual for a solution but couldn't find any. Has anyone else had this problem and/or found a solution?
 
Can you post your scenario or screenshots (or both :) ) of the issue?
 
Here is the Scenario:

BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
System Sol
Date MJD 58255.1285143230
END_ENVIRONMENT

BEGIN_FOCUS
Ship CTV-02-A-v1
END_FOCUS

BEGIN_CAMERA
TARGET CTV-02-A-v1
MODE Cockpit
FOV 60.00
END_CAMERA

BEGIN_HUD
TYPE Orbit
REF AUTO
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 1 58255.12851432303 0 0 0.834315900510215 0 58495.29033495492 0
DVProg 0 0 0 1
AdvConf 0 0 1 0 0
Guidance 0
END
EjectMFD V5
Reference Auto
Data 0 1 3 0 0 58255.13438440519 2773.14
Guidance 0
END
BaseAprMFD V2
Reference Auto
Target none
Source none
DataA 0 0 120000 0.10821 0.366519 1 1 58255.11842663791 58255.11842663791 0
DataB 0 3 0 1 0 1
END
SlingMFD V4
Reference Auto
Source none
Data 0 1 1 3 0 1 58255.11842663791 0
END
LaunchMFD V4
Target None
Data 0 1 1 3 0 1 0
END
CF1_DataA 0 0
CF1_DataB 58255.1183692698 10 120000 2 20 150000
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 1 58255.12851432303 0 0 0.834315900510215 0 58495.29033495492 0
DVProg 0 0 0 1
AdvConf 0 0 1 0 0
Guidance 0
END
EjectMFD V5
Reference Auto
Data 0 1 3 0 0 58255.13438440519 2773.14
Guidance 0
END
BaseAprMFD V2
Reference Auto
Target none
Source none
DataA 0 0 120000 0.10821 0.366519 1 1 58255.11842663791 58255.11842663791 0
DataB 0 3 0 1 0 1
END
SlingMFD V4
Reference Auto
Source none
Data 0 1 1 3 0 1 58255.11842663791 0
END
LaunchMFD V4
Target None
Data 0 1 1 3 0 1 0
END
CF1_DataA 0 0
CF1_DataB 58255.1183692698 10 120000 2 20 150000
CF1_SecTgt
mfdShare -1
mfdProgram 3
END_MFD

BEGIN_SHIPS
CTV-02-A-v1:CTV-02-A-v1
STATUS Orbiting Earth
RPOS -5070092.16 532609.48 4277910.87
RVEL -5004.985 -362.962 -5891.577
AROT -173.29 8.58 62.22
AFCMODE 7
PRPLEVEL 0:0.996024
DOCKINFO 0:0,CEV
NAVFREQ 0 0
XPDR 468
RCS 1
CTRL_SURFACE 1
CONFIGURATION 1
CURRENT_PAYLOAD 0
SEQ 0 2 0.998667
SEQ 1 -2 0.000333
SEQ 2 -2 0.000333
SEQ 3 -2 0.000000
SEQ 4 -2 0.000000
END
CEV:CEV-Orion\CEV-Orion
STATUS Orbiting Earth
RPOS -5070097.56 532605.30 4277875.35
RVEL -5004.985 -362.962 -5891.577
AROT 6.71 -8.58 117.78
RCSMODE 2
AFCMODE 7
PRPLEVEL 0:0.220283
DOCKINFO 0:0,CTV-02-A-v1
NAVFREQ 0 0
XPDR 468
MODE 1
SOLAR 1
LAS 0
SMFUEL 0.600000
END
habitatlander:DRM1_hab
STATUS Orbiting Mars
RPOS 14980107.98 -1697166.72 -2756250.44
RVEL 1690.002 12.954 799.053
AROT -164.65 -52.74 -96.66
VROT -0.07 0.00 0.00
AFCMODE 7
PRPLEVEL 0:0.856028
NAVFREQ 0 0
CONFIG 1 1 1
AUTO 0
END
cargolander:DRM1_cargo
STATUS Landed Mars
POS -67.6558444 -18.9084541
HEADING 74.90
RCSMODE 2
AFCMODE 7
PRPLEVEL 0:0.048010
NAVFREQ 0 0
CONFIG 1 1 1 0
AUTO 0
UCGO @@0,1,1,9000,CargoFissionReactorAuto,@@1,1,1,100,CargoSolarBalloonAuto,
UCGO @@2,1,1,100,CargoWeatherBalloonAuto,@@3,1,1,3217,CargoTeleroverAuto,@@4,1,1,567,CargoBaseGreenhouse,
UCGO @@5,1,1,9000,CargoGreenhouseInterior,@@6,1,1,2874,CargoBaseModule,@@7,1,1,2874,CargoBaseModule,
END
-Booster:CEV-Orion\Ares1-Booster
STATUS Landed Earth
POS -76.7868436 28.2761603
HEADING 250.34
AFCMODE 7
END
-LAS:CEV-Orion\Ares1-LAS
STATUS Landed Earth
POS -76.1332611 28.2175996
HEADING 350.88
AFCMODE 7
END
CEV-LHF:CEV-Orion\Ares1-fairing1
STATUS Landed Earth
POS -76.7644245 28.2764330
HEADING 96.33
AFCMODE 7
END
CEV-RHF:CEV-Orion\Ares1-fairing1
STATUS Landed Earth
POS -76.7492847 28.2744198
HEADING 95.44
AFCMODE 7
END
-Second:CEV-Orion\Ares1-Second
STATUS Landed Earth
POS 135.0260939 -16.8032509
HEADING 65.38
AFCMODE 7
NAVFREQ 0 0
END
END_SHIPS

BEGIN_ReFuelMFD
SCENARIO_TREE
NAMED Computers
END_NODE
END_NODE
END

And here are the addons that i used:

[ame="http://www.orbithangar.com/searchid.php?ID=2713"]Crew Transfer Vehicles v0.96[/ame]

[ame="http://www.orbithangar.com/searchid.php?ID=5208"]Design Reference Mission 1 v1.4[/ame]

[ame="http://www.orbithangar.com/searchid.php?ID=4437"]CEV-Orion[/ame]
 
You need to have EIn less than 1 degree for off-axis to work.

There is also a bug, where you need to restart Orbiter right after you select off-axis mode to reset the TEj from NAN.
 
I reproduced the issue
Here is the scenerio I used (I just removed the other vessels to reduce scenerio clutter)
Code: 
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
System Sol
Date MJD 58255.1285143230
END_ENVIRONMENT

BEGIN_FOCUS
Ship CTV-02-A-v1
END_FOCUS

BEGIN_CAMERA
TARGET CTV-02-A-v1
MODE Cockpit
FOV 60.00
END_CAMERA

BEGIN_HUD
TYPE Orbit
REF AUTO
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 1 58255.12851432303 0 0 0.834315900510215 0 58495.29033495492 0
DVProg 0 0 0 1
AdvConf 0 0 1 0 0
Guidance 0
END
EjectMFD V5
Reference Auto
Data 0 1 3 0 0 58255.13438440519 2773.14
Guidance 0
END
BaseAprMFD V2
Reference Auto
Target none
Source none
DataA 0 0 120000 0.10821 0.366519 1 1 58255.11842663791 58255.11842663791 0
DataB 0 3 0 1 0 1
END
SlingMFD V4
Reference Auto
Source none
Data 0 1 1 3 0 1 58255.11842663791 0
END
LaunchMFD V4
Target None
Data 0 1 1 3 0 1 0
END
CF1_DataA 0 0
CF1_DataB 58255.1183692698 10 120000 2 20 150000
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 1 58255.12851432303 0 0 0.834315900510215 0 58495.29033495492 0
DVProg 0 0 0 1
AdvConf 0 0 1 0 0
Guidance 0
END
EjectMFD V5
Reference Auto
Data 0 1 3 0 0 58255.13438440519 2773.14
Guidance 0
END
BaseAprMFD V2
Reference Auto
Target none
Source none
DataA 0 0 120000 0.10821 0.366519 1 1 58255.11842663791 58255.11842663791 0
DataB 0 3 0 1 0 1
END
SlingMFD V4
Reference Auto
Source none
Data 0 1 1 3 0 1 58255.11842663791 0
END
LaunchMFD V4
Target None
Data 0 1 1 3 0 1 0
END
CF1_DataA 0 0
CF1_DataB 58255.1183692698 10 120000 2 20 150000
CF1_SecTgt
mfdShare -1
mfdProgram 3
END_MFD

BEGIN_SHIPS
CTV-02-A-v1:CTV-02-A-v1
STATUS Orbiting Earth
RPOS -5070092.16 532609.48 4277910.87
RVEL -5004.985 -362.962 -5891.577
AROT -173.29 8.58 62.22
AFCMODE 7
PRPLEVEL 0:0.996024
DOCKINFO 0:0,CEV
NAVFREQ 0 0
XPDR 468
RCS 1
CTRL_SURFACE 1
CONFIGURATION 1
CURRENT_PAYLOAD 0
SEQ 0 2 0.998667
SEQ 1 -2 0.000333
SEQ 2 -2 0.000333
SEQ 3 -2 0.000000
SEQ 4 -2 0.000000
END
CEV:CEV-Orion\CEV-Orion
STATUS Orbiting Earth
RPOS -5070097.56 532605.30 4277875.35
RVEL -5004.985 -362.962 -5891.577
AROT 6.71 -8.58 117.78
RCSMODE 2
AFCMODE 7
PRPLEVEL 0:0.220283
DOCKINFO 0:0,CTV-02-A-v1
NAVFREQ 0 0
XPDR 468
MODE 1
SOLAR 1
LAS 0
SMFUEL 0.600000
END
END_SHIPS

Even when resetting IMFD and trying a new plan the problem still arises; autburn shuts off around 30 seconds into the burn. Normally, one could just use BV view to manually complete the burn, but even with the alignment cross centered, the required dV value increases.
 
1.9 ks

On odd thing involves the calculated burn position. Normally on long burns, the burn position is before the ejection point (so the burn "straddles" the ejection point)
In this setup the burn position is the same as the ejection point.

Also, AB disables itself when dV remaining stops decreasing
 
1.9 ks, as in 1900 seconds? :facepalm:

Well there you go. That's probably more than a third of the parking orbit's period. It's too long.

Especially Realtime will fail, because it is only useful when your burntime is small relative to your period. I think even Off-Axis is having a hard time.

Search the thread for breaking a long burn into smaller burns. Search hint: the thread had references to Phobos Grunt.

Edit: Try here http://www.orbiter-forum.com/showthread.php?t=31519&highlight=Phobos+Grunt
 
Last edited:
I know that realtime won't work the problem is that it won't let me change it to off-axis.
 
D'oh :facepalm: Thanks booga

@snaps
The reason why IMFD fails is because you cannot do one burn to get to Mars with the CTV, regardless of burn guidance mode. The vehicle just doesn't have enough thrust.

To get to mars, you must do several small burns which slowly raise your apoapsis.

In Orbit Eject, push autoburn and watch the burn in Burn Vector view. Disable Autoburn when you have burned for around 200-300 seconds.
Back in the main orbit eject mode, select "Course" and toggle it to another mode and back to course. This selects the next ejection. Push autoburn again, and let AB burn for another 200-300 seconds.
Continue doing this until burn time is zero.
 
That's sounds like it migt work so ill give ir a try. However I would still like to be able to change the burn guidance mode to Off-Axis just in case I need it some other time as well as the fact that I would like to keep the number of TMI burns down to 2 if possible because that is what NASA's DRM (what I am trying to copy as best I can) calls for.
 
I was able to change the burn guidance mode; are you sure you are changing it in Orbit Eject? Also, I noticed that sometimes Off-axis switches back to realtime when a single TMI burn isn't possible.

Honestly, burn guidance mode doesn't matter that much. It's basically how IMFD "does the math"
Realtime mode compares your current orbit with the target orbit, and calculates how much dV would have to be applied, and recalculates this value in "realtime" (this is actually the only mode that TransX works in)

Off-axis integrates your position over the whole burn - it essentially calculates your entire burn at once. Because it calculates the whole thing, it also accounts for your delta position over the burn; this makes it slightly more efficent than Realtime. When off-axis switches back to realtime, it failed to find a way to make a single burn (which will happen in this case)

I tried to only use two TMI burns, and it is possible, but is less efficient than several TMI burns. I used the prograde autopilot and the burnvector view, and burned prograde from 500 seconds before IMFD's burn time, and 500 seconds after. On the next orbit, I started burning 500 seconds before, and engaged autoburn to finish off the burn.
 
I am able to change burn guidance mode in orbit eject but not in course. There is a picture in the IMFD manual with it set to Off-Axis in course mode which makes me think someting is wrong.

I did manage to get a 2 burn TMI buy doing basicaly what said meson. I used the prograde autopilot to get my apogee up to 20 M and then came around and used auto burn for the second burn.

However when I continue the flight I switch to transx to monitor my closest approach and I notice that it has me ending up rather far from mars and as I keep going this nummber keeps changing. I know that transx says the closest aproach estimate is rough but is it really that inaccurate or is IMFD not putting me close enough to mars. If it is just transx being inaccurate is tere some other mfd tat could give me a better estimate? (I know this mabye should be the topic of another thread but sence we are on the topic of a mars mission I fugured that iwould ask)
 
Snaps2010 said:
I am able to change burn guidance mode in orbit eject but not in course. There is a picture in the IMFD manual with it set to Off-Axis in course mode which makes me think someting is wrong.
Click to expand...


If you are going to Mars, then your source in course is Earth. Earth doesn't have some huge rocker engine. It isn't actually going with you. Therefore, course doesn't calculate a burn vector at all, it hands information off to orbit eject, which does that.

Course will NOT generate a burn vector at all if the source is not yourself. I would not be surprised if it didn't let you change burn guidance; there is no burn vector!

Oh, and to see where you are actually going, learn to use IMFD's powerful map feature. I takes more into account than either TransX or IMFD's own course plan.
 
Oh ok that makes sense. I thaught that when the guidance mode kept changing back to realtime in orbit eject it was because it was set set to realtime in course. Thanks for clearing that up for me.

Ill look into the map feature but I still wonder how accurate the auto burn is. Will it get me right were I want to go or will I need some mid-course corections and if so how much fuel will the corections cost?
 
Autoburn is very accurate, but IMFD doesn't account for the influence of every body in the solar system. You usually have to make some mid-course corrections (just by hitting autoburn in Target Intercept); even NASA makes mid-course corrections ;)

Mid course corrections will probably cost less than 200 m/s of dV
 
Off-Axis is more accurate than realtime for long burns.

I like IMFD better than TransX because of its powerful map. If you offset your target properly, you can do see the "real" result in the map. This lets you stay one step ahead of the course program. You can get the total MCCs delta-V of a Mars mission down to just 10s of m/s if you offset properly.
 
So is there a way to set my course so that I will aproach mars in such a way that it will minimize the fuel required to enter a specific orbit. For exapmle, in the scinario I posted earlier there is a lander in mars orbit and I need to enter a neer identical orbit and be close enough to randevou with it in a few orbits.
 
The IMFD map will tell you your equatorial inclination and the longitude and latitude of periapsis. You can use this to try to approach a similar inclination to your target.

When you get to Mars SOI, then you can target the lander.
 
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