TransX Hohmann transfer - Mars - Orbiter-Forum

orbekler · 05-12-2012, 09:53 AM

Hello, I'm trying to perform a tangential transfer to Mars with TransX.

I performed the same, "almost-partially-successful"

with IMFD, that helped me to reach Mars Soi.

With TransX i set the date of departure as in IMFD, and after some tweaking, I got a reasonable Encounter plan, within some Mmeters, I passed to Escape view, but here I got the first problem: even after resetting and transferring all params from Encounter to Escape Manoeuvre , I don't go nearer than 1.2Gmeters from Mars.

I used Prograde, Plane change, and a very tiny refinement of (ejection) Date (souldn't be different from IMFD's one).

Eventually I disrupted the orbit, I even tried to adjust Outward velocity, that shouldn't be touched in a Hohmann transfer, to no avail. Working with the "get near, change parameter, get near, chenage again parameter" seems not working here.

I'm asking for help to anyone did a tangential transfer with TransX, here is the Scenario (Arrow Frighter): how do you plan it?

Code:

BEGIN_DESC
Orbiter saved state at T = 4342
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 58243.0521836997
END_ENVIRONMENT

BEGIN_FOCUS
  Ship AR01
END_FOCUS

BEGIN_CAMERA
  TARGET AR01
  MODE Cockpit
  FOV 50.00
  BEGIN_PRESET
    Cockpit:AR01:50.00
  END_PRESET
END_CAMERA

BEGIN_HUD
  TYPE Orbit
  REF AUTO
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE TransX
  Ship  AR01
  FNumber 3
  Int 1
  Orbit True
  Vector  6135565.72404 -634626.068181 2709881.18089
  Vector  -3105.26882369 185.098544973 7039.32179818
  Double  3.98600439969e+014
  Double  58243.0172177
  Handle Earth
  Handle NULL
  Handle NULL
Select Target
 0 Escape
Autoplan
0 0
Plan type
0 0
Plan
0 1
Plan
0 0
Plan
0 0
Select Minor
 0 None
Manoeuvre mode
0 1
Base Orbit
0 0
Prograde vel.
 4  3427.965191
Man. date
 5  58244.2546867
Outward vel.
 2  -677.57
Ch. plane vel.
 3  1241.89673781
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Pe Distance
 0  7645212
Ej Orientation
 0  0
Equatorial view
0 0
Finvars
  Finish BaseFunction
  Int 2
  Orbit True
  Vector  -105750530032 -26193762.4694 -107723261032
  Vector  22953.6760096 -295.680148644 -22556.5373124
  Double  1.32712838556e+020
  Double  58244.255453
  Handle Sun
  Handle Earth
  Handle Mars
Select Target
 0 Mars
Autoplan
0 0
Plan type
0 2
Plan
0 0
Plan
0 0
Plan
0 1
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 0
Prograde vel.
 0  0
Man. date
 0  58243.052174
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Prograde vel.
 6  0
Eject date
 6  58243.0389585
Outward vel.
 0  0
Ch. plane vel.
 6  0
Finvars
  Finish BaseFunction
  Int 5
  Orbit False
  Handle Mars
  Handle NULL
  Handle NULL
Select Target
 0 None
Autoplan
0 0
Plan type
0 1
Plan
0 0
Plan
0 2
Plan
0 0
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 1
Prograde vel.
 0  0
Man. date
 0  58243.0512516
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Draw Base
0 0
Finvars
  Finish BaseFunction
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE TransX
END_MFD

BEGIN_SHIPS
AR01:UCGO\Vessels\UCGOArrowFreighter
  STATUS Orbiting Earth
  RPOS -4985181.49 543192.24 -4501270.71
  RVEL 5116.324 -392.756 -5733.257
  AROT -168.77 0.82 -172.04
  RCSMODE 2
  AFCMODE 4
  PRPLEVEL 0:0.998919
  IDS 0:320 100
  NAVFREQ 0 0
  XPDR 300
  O2_RESERVE 92.12
  SAVEVAR00 0§0,1§0.00,2§0,3§0.00,4§0,5§0.00,6§0,7§1,8§0.00,9§1,10§0.00,11§0.00,12§0,13§1,14§1,15§0.00,16§0,17§0,18§1,19§1,20§4,21§0,22§1,
  UMMUCREW Capt-William_Johnes-53-70-70
  UMMUCREW XI0-Lee_Nash-39-65-78
  UMMUCREW XI1-Kara_Miller-32-65-58
  UMMUCREW XI2-Sharon_Valerii-26-67-54
  UMMUCREW XI3-Cameron_Mitchell-36-65-77
  UMMUCREW XI4-Samantha_Carter-33-66-53
  UMMUCREW XI5-Daniel_Jackson-35-68-75
  UMMUCREW XI6-Teal_c-31-64-104
  UMMUCREW XI13-Carson_Beckett-38-74-95
  UMMUCREW XI12-Ronon_Dex-32-63-97
  UMMUCREW XI10-Rodney_McKay-35-72-90
  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,
  UCGO @@8,1,0,0,@@9,1,0,0,@@10,1,0,0,@@11,1,0,0,@@12,1,0,0,@@13,1,0,0,@@14,1,0,0,
  UCGO @@15,1,0,0,@@16,1,0,0,@@17,1,0,0,@@18,1,0,0,@@19,1,0,0,@@20,1,0,0,@@21,1,0,0,
  UCGO @@22,1,0,0,@@23,1,0,0,@@24,1,0,0,@@25,1,0,0,@@26,1,0,0,@@27,1,0,0,@@28,1,0,0,
  UCGO @@29,1,0,0,@@30,1,0,0,@@31,1,0,0,@@32,1,0,0,@@33,1,0,0,@@34,1,0,0,@@35,1,0,0,
  UCGO @@36,1,0,0,@@37,1,0,0,@@38,1,0,0,@@39,1,0,0,
END
END_SHIPS

BEGIN_WatchdogMFD
  COUNT 0
END

BEGIN_ExtMFD
END

BEGIN_uap
END

flytandem · 05-16-2012, 02:50 AM

Not sure how much help I will be. I don't have the ship you are flying so I modified it to be a deltaglider. Then on startup, transx was not responding so I think you may not be using the latest transx version. (which BTW is found here)...
http://orbiterfixes.googlecode.com/f...raphicsfix.zip

So I at least kept the exact orbit position and date and fired up my transx and started from scratch. The plan I found showed a fairly easy nearly hohmann transfer some dozen days later. I usually set up a plan first then climb to orbit to match the plan. It's harder doing it from an existing orbit. I then did my usual which is to replace the plan with a maneuver. Save (below) is 8 minutes before burn. A fairly light burn at a bit over 3500 m/s.

Code:

BEGIN_DESC

END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 58255.9218404124
END_ENVIRONMENT

BEGIN_FOCUS
  Ship AR01
END_FOCUS

BEGIN_CAMERA
  TARGET AR01
  MODE Cockpit
  FOV 50.00
  BEGIN_PRESET
    Cockpit:AR01:50.00
  END_PRESET
END_CAMERA

BEGIN_HUD
  TYPE Orbit
  REF AUTO
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE TransX
  Ship  AR01
  FNumber 3
  Int 1
  Orbit True
  Vector  3207543.62148 -397596.970269 5919692.52582
  Vector  -6729.85633999 578.307108741 3668.94678437
  Double  3.98600439969e+014
  Double  58255.9090878
  Handle Earth
  Handle NULL
  Handle NULL
Select Target
 0 Escape
Autoplan
0 0
Plan type
0 0
Plan
0 1
Plan
0 0
Plan
0 0
Select Minor
 0 None
Manoeuvre mode
0 1
Base Orbit
0 0
Prograde vel.
 0  3527.72957796
Man. date
 0  58255.9289973
Outward vel.
 0  -2.45
Ch. plane vel.
 0  32.68
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 3
Scale to view
0 0
Advanced
0 0
Pe Distance
 0  6677481.79917
Ej Orientation
 0  0.0767944870878
Equatorial view
0 0
Finvars
  Finish BaseFunction
  Int 2
  Orbit True
  Vector  -82904790073.5 -6174934.998 -126676656305
  Vector  26710.8010102 -195.94501541 -18003.1156564
  Double  1.32712838556e+020
  Double  58255.9289934
  Handle Sun
  Handle Earth
  Handle Mars
Select Target
 0 Mars
Autoplan
0 0
Plan type
0 2
Plan
0 0
Plan
0 0
Plan
0 1
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 0
Prograde vel.
 0  0
Man. date
 0  58255.92184
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Prograde vel.
 0  0
Eject date
 0  58255.9660311
Outward vel.
 0  0
Ch. plane vel.
 0  0
Finvars
  Finish BaseFunction
  Int 5
  Orbit True
  Vector  -1360760865.78 1135184891.94 5287366608.55
  Vector  806.35597157 -668.780845456 -3157.16145113
  Double  4.28282991638e+013
  Double  58475.8298904
  Handle Mars
  Handle NULL
  Handle NULL
Select Target
 0 None
Autoplan
0 0
Plan type
0 1
Plan
0 0
Plan
0 2
Plan
0 0
Select Minor
 0 None
Manoeuvre mode
0 0
Base Orbit
0 0
Prograde vel.
 0  0
Man. date
 0  58255.9217942
Outward vel.
 0  0
Ch. plane vel.
 0  0
Intercept with
0 0
Orbits to Icept
0 0
Graph projection
0 0
Scale to view
0 0
Advanced
0 0
Draw Base
0 0
Finvars
  Finish BaseFunction
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE TransX
END_MFD

BEGIN_SHIPS
AR01:Deltaglider
  STATUS Orbiting Earth
  RPOS -4619036.00 359299.57 4883522.34
  RVEL -5551.136 609.509 -5303.679
  AROT 179.05 5.90 174.19
  AFCMODE 4
  PRPLEVEL 0:0.998919 1:0.997810
  IDS 0:320 100
  NAVFREQ 0 0 0 0
  XPDR 300
  AAP 0:0 0:0 0:0
END
END_SHIPS

BEGIN_VistaBoost
END

orbekler · 05-17-2012, 07:54 AM

Thank you, I'll try this scenario, I'll let you know.

---------- Post added 17th May 2012 at 09:54 ---------- Previous post was 16th May 2012 at 11:05 ----------

The first attempt was not very satisfying, here the trip:

I had trouble to make the MCC cause the direction of the burn vector (the cross) was slipping far away from the center immediately after few dV burn (had about 200dV total to accomplish).

I'm going to try it over and over again util the result is acceptable (at least within Soi).

**C3PO** · 05-17-2012, 11:31 AM

778.6 km from the center of Mars is well inside the SoI.

It's going to drift, but that's why we do correction burns.

orbekler · 05-17-2012, 12:17 PM

Quote:

Originally Posted by C3PO

778.6 km from the center of Mars is well inside the SoI.

It's going to drift, but that's why we do correction burns.

I'm actually 1AU far away from Mars (is really that much?).

That's why I enabled Interplanetary Map, to show that I missed the planned TransX target orbit at encounter point.

**C3PO** · 05-17-2012, 02:45 PM

The left screen suggests you're about 1/3 the way to Mars.

---------- Post added at 03:45 PM ---------- Previous post was at 01:33 PM ----------

Are you sure you're using the scenario posted by flytandem? I just flew that plan (not very accurately) and ended up doing the orbit insertion at MJD 58494.58.

orbekler · 05-18-2012, 07:09 AM

Quote:

Originally Posted by C3PO

The left screen suggests you're about 1/3 the way to Mars.

---------- Post added at 03:45 PM ---------- Previous post was at 01:33 PM ----------

Are you sure you're using the scenario posted by flytandem? I just flew that plan (not very accurately) and ended up doing the orbit insertion at MJD 58494.58.

What I find really strange is that Mars moved to the encounter point (one o' clock), while it seems that Deltaglider freezed in the same place (4 o' clock).

It' exactly the same scenario, only, I downloaded as suggested by flytandem TransX patch but I forgot to extract it, maybe that is the problem.

**Goth** · 06-01-2012, 01:07 PM

@orbekler
From the screenshots you've posted, I see two problems.
1, all the lines are green, you can solve this quitting and re-opening orbiter. That bug should disappear.
Anyway if you correctly install the fixed version of TransX you won't have this problem anymore.
2, the most important one, you didn't do midcourse corrections and you still have the old manouvre on.
So, put the manouvre off.
If that bug is present, quit and re-open Orbiter.
When you are 1/2 or 3/4 the way to Mars, do a midcourse correction.
To do this, you must be far from Earth SOI so that the first stage disappears.
Make a new manouvre (Manouvre ON) and change both the variables Outward velocity and plane change, taking into account that:
change plane will improve your closest approach while outward velocity will also do it, but it will also change the PeA a lot. So use the plane change velocity to reach the best closest approach you can, then change the outward velocity to make your trajectory not crashing into Mars' surface and at the same time to be not too far to miss the planet.
I've attached two scenarios which is the continuation of the trip starting from the scenario flytandem provided.

Buona fortuna.

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05-17-2012, 07:54 AM	#3
orbekler Orbinaut	Thank you, I'll try this scenario, I'll let you know. ---------- Post added 17th May 2012 at 09:54 ---------- Previous post was 16th May 2012 at 11:05 ---------- The first attempt was not very satisfying, here the trip: I had trouble to make the MCC cause the direction of the burn vector (the cross) was slipping far away from the center immediately after few dV burn (had about 200dV total to accomplish). I'm going to try it over and over again util the result is acceptable (at least within Soi).

05-17-2012, 11:31 AM	#4
C3PO Donator	778.6 km from the center of Mars is well inside the SoI. It's going to drift, but that's why we do correction burns.

05-17-2012, 12:17 PM	#5
orbekler Orbinaut	Quote: Originally Posted by C3PO 778.6 km from the center of Mars is well inside the SoI. It's going to drift, but that's why we do correction burns. I'm actually 1AU far away from Mars (is really that much?). That's why I enabled Interplanetary Map, to show that I missed the planned TransX target orbit at encounter point.

05-17-2012, 02:45 PM	#6
C3PO Donator	The left screen suggests you're about 1/3 the way to Mars. ---------- Post added at 03:45 PM ---------- Previous post was at 01:33 PM ---------- Are you sure you're using the scenario posted by flytandem? I just flew that plan (not very accurately) and ended up doing the orbit insertion at MJD 58494.58.

05-18-2012, 07:09 AM	#7
orbekler Orbinaut	Quote: Originally Posted by C3PO The left screen suggests you're about 1/3 the way to Mars. ---------- Post added at 03:45 PM ---------- Previous post was at 01:33 PM ---------- Are you sure you're using the scenario posted by flytandem? I just flew that plan (not very accurately) and ended up doing the orbit insertion at MJD 58494.58. What I find really strange is that Mars moved to the encounter point (one o' clock), while it seems that Deltaglider freezed in the same place (4 o' clock). It' exactly the same scenario, only, I downloaded as suggested by flytandem TransX patch but I forgot to extract it, maybe that is the problem.