TransX LEO to moon - without mid-course inclination change?

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laukejas

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Going to Moon's base from Earth surface or LEO with TransX is one of easiest things to do. However, all tutorials advise to get on same inclination of Moon, and when in SOI, change inclination using Map MFD to get orbit on top of destination base.

However, I'm going here for more advanced, and maybe more fuel efficient way: to make the ejection burn with inclination change, so that I arrive on Moon, passing over the required base already, with no inclination burn on SOI required.

But I can't find correct way to do this. My base is 080E 26N on the Moon, and when planning the burn from LEO, in the Encounter window, I don't know what numbers to aim form. Since it is 26N, I guess I have to go for 26 degrees inclination. I can make that number happen. But what about LAN? What does it have to be? -80? Thing is, I can't change these numbers independently, changing any of burn vectors changes both inclination and LAN. So how do I do it? How do I set them both to correct values?
 
laukejas said:
Going to Moon's base from Earth surface or LEO with TransX is one of easiest things to do. However, all tutorials advise to get on same inclination of Moon, and when in SOI, change inclination using Map MFD to get orbit on top of destination base.

However, I'm going here for more advanced, and maybe more fuel efficient way: to make the ejection burn with inclination change, so that I arrive on Moon, passing over the required base already, with no inclination burn on SOI required.

But I can't find correct way to do this. My base is 080E 26N on the Moon, and when planning the burn from LEO, in the Encounter window, I don't know what numbers to aim form. Since it is 26N, I guess I have to go for 26 degrees inclination. I can make that number happen. But what about LAN? What does it have to be? -80? Thing is, I can't change these numbers independently, changing any of burn vectors changes both inclination and LAN. So how do I do it? How do I set them both to correct values?
Click to expand...

There has to be some math involved. You have to determine the LAN and INC of earth that corresponds to your base on the moon; because the earth and moon aren't coplanar. I'm not very good at geometry, so I don't know, but I'm thinking you would first subtract the moon's base difference in inclination from the earth's reference plane(I'm thinking it's like 2 degrees or something) and subtract that from the equator to get -2(about) then subtract the LAN of the lunar base from the equator(for a LAN of 30, so your earth burn's LAN would be -32 for a base with a lan of 30 and assuming the difference between the earth and the moon's planes is 2.

Take that with a truckload of salt, because I'm just taking pre-calculus ATM.
 
I often go Earth to Moon to arrive at or over a specific base on the first orbit. It is not by using math but just tweaking or iterating TransX variables, usually prograde and date only, for the eject burn. I think it is best done by being well out of plane with the moon while in LEO.

If you get your ship into LEO and well out of plane with the moon then post the scenario, I will give it a shot and re post with the TransX maneuver set up and ready to burn. Since I don't have your base perhaps I can use Brighton Beach as an example moon base to aim for.

To get the base to show up in stage 3 of TransX requires having Map MFD up, reference moon, target the particular base in this case Brighton. If TransX loses the base while en route to the moon, you will have to re target the base in Map MFD. Not sure why this happens but thought I'd mention it as a heads up.

BTW, there will be mid course corrections needed as is usually the case in TransX plans/flights but they should be minimal.
 
Okay, I'm posting a scenario, simple DG in 124km LEO, 5.52 rInc to Lunar plane (should be enough?), Brighton Beach selected in Map MFD, TransX not optimized, just added enough prograde velocity. Ejection right now is about perpendicular to planar nodes, although it is possible to delay ejection by about a week, and eject on node, but I guess you wanted to eject with some rInc?

Anyways, from this scenario, what's the following step to set up TransX to get a trajectory over Brighton Beach?
 

Attachments

Or you can use LunarTransfer MFD by jarmonik, witch does exactly what you want: Go directly from LEO to base-aligned orbit in Moon, in only one orbit. Very IMFD-like and really easy to use.
But you may want to do this "manually" ...
 
I second the Lunar Transfer MFD recommendation. In my book, it is the best way to go from the Earth to the Moon.
 
Thirded. Plug and play, all the way.

(Great mini-series, by the way. Though I officially and blatantly digress.)
 
Lunar Transfer MFD is not recommended ONLY if you are trying to do a manual transfer. It's excellent, very precise.
 
You can do it in IMFD also. Under the configuration is the "Landing Target" option. Use the offsetting in target intercept in conjunction with the IMFD map, which will display the angular difference between you orbital plane and the landing target. It takes some trial and error with tweaking the offset variables, but I have gotten a ~3180 m/s TLI to Brighton Beach which needed only a 6 m/s mid course correction with the Base Approach feature, and that was performed only well within the Moon's SOI.

Basically, you can do "by hand" in IMFD what Lunar transfer MFD does, but you get a better sense of how it works, and you can even be a little more efficient.

IMHO, the "Landing Target" is the most useful feature of IMFD that no one talks about.
 
Haven't looked at Lunar Transfer but if it's like IMFD (automated) I would rather do it manually since I believe it provides a better learning environment to visualize what is physically happening. Playing with Transx is like sculpting in 4 dimensions. I would rather do the sculpting myself than buy a sculpted work of art. But, to each their own.

The 5 degree off-plane is enough to get a good selection of north/south arrival position at the moon. You see, by making slight change in when you do the eject burn it is using the arrival plane (tilted relative to the moon's plane) to position either to arrive more in the northern or southern hemispheres of the moon. And the strength of the burn positions more to arrive either beyond or short of the moon meaning it is good for adjusting the height above the lunar surface on the first pass where the orbit insert will be done.

After about 5 minutes I had the scenario posted below.

Things I noticed...
The initial scenario had the burn happening a long way from the node with the moon. You will need to do the burn about a week later or more to position the arrival more towards the node.

The shallow 5 degree off-plane made me have to push the timing of the arrival a little bit past the node. But after a few back and forths between later date (just a few seconds later) and less burn strength it showed up as a good arrival.

You should start the scenario and then do the following to see the pass near Brighton...
1. Show the lunar base in Transx. To do this open Map MFD, ref Earth, target Brighton Beach. Then in Transx, go to stage 3, then in TransX click VW and choose Encounter View. This will show a yellow dashed line segment that goes from center of moon to base location. And in text it will state the offplane distance and it should be down around a couple of Km.
2. In Transx setup view, click var to show graph projection : Focus. I find this easier to actually see my arrival orbit. The yellow dashed line should extend out to the circumference of the circle of the moon as you should expect if you are going to pass over the base on the first orbit.

Note. I would not actually go forward in time (warping the week+ to the burn) and expect that the planned maneuver will actually still be showing the arrival near the base. Instead you should warp ahead then set up the planned maneuver again when just 15 to 30 minutes from the burn.

Plus I just noticed that the scenario has the ship still feeling the atmosphere. If you don't nudge it higher like closer to 200 Km than Pe= 115 Km agl, you will not be able to warp ahead that week without falling back onto the Earth.

I hope this explanation of using off-plane to arrive at a specific lunar base helps.

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I would also go now with manual approach. I want to learn. I'm sure there are tools which does everything for you, but right now, I want to understand how it works.

Flytandem, I tried your method several times, with huge success, I think I understand how system works. Thank you.

However, after ejection burn, even though off-plane distance is less than 1km, it goes up to 250km when in Moon Pea if no correction burn is made. Why is it so inaccurate? I mean I know that TransX isn't as accurate as IMFD, but this is Earth-Moon, just a few days trip, relatively short distance, and still... Non-spherical gravity sources are turned off.
Any way in increasing accuracy here? I can't really make MCC early, because numbers are jumping around when I'm halfway, and when entering Moon's SOI, it's a bit expensive.

Of course, we're talking a few meters of dV here, but that TransX inaccuracy tends to lead to very expensive MCC's in other missions - like that Chapman Probe insertion at Mercury's orbit. I can't make MCC early (when it is dV cheap) because numbers aren't reliable, and it's too expensive to make it late, when they are.

Maybe there are plans to release new version of TransX with increased accuracy?
 
Why is it so inaccurate? I mean I know that TransX isn't as accurate as IMFD, but this is Earth-Moon, just a few days trip, relatively short distance, and still... Non-spherical gravity sources are turned off.
Click to expand...

I'm not 100% sure, but TransX uses 3-body solution. Lunar Transfer and IMFD's Map screen use more elaborate calculations.
 
I also ran the flight just now. And found same 250 Km change of off-plane distance by the time I was half way to the moon. So a small 3 m/s correction first got me to zero in the maneuver and I saw which way it was changing to increase the maneuver amount by a couple of m/s to make it trying to miss the off-plane target by about 150 Km. A bit like a marksman allowing for a moving target and shooting ahead of the target to hit it. As hoped for it was a fairly good guess at the remaining error and had me in the orbit insert with still about 50 Km off-plane. I mixed in the plane change with the orbit insert and it only needed 0.1% extra insert dv. This illustrates the art of Transx use. I also wish it were more accurate but I will still rather prefer seat of pants flying even if it requires a bit of art. OK maybe especially if it requires a bit of art.
 
flytandem said:
Haven't looked at Lunar Transfer but if it's like IMFD (automated) I would rather do it manually since I believe it provides a better learning environment to visualize what is physically happening. Playing with Transx is like sculpting in 4 dimensions. I would rather do the sculpting myself than buy a sculpted work of art. But, to each their own.
Click to expand...


I'll give you that Lunar Transfer MFD is totally automated, and you really don't have to have any idea what is going on. But IMFD is only semi-automated. Sure, noobs can hit target-moon-autoburn, sit back, and fly a reasonable course to the moon. But, if using the offsetting feature in conjunction with the powerful n-body Map feature, then an experienced user will have manual control over five variables, with which he/she can so some incredibly precise flying.

flytandem said:
The 5 degree off-plane is enough to get a good selection of north/south arrival position at the moon. You see, by making slight change in when you do the eject burn it is using the arrival plane (tilted relative to the moon's plane) to position either to arrive more in the northern or southern hemispheres of the moon. And the strength of the burn positions more to arrive either beyond or short of the moon meaning it is good for adjusting the height above the lunar surface on the first pass where the orbit insert will be done.
Click to expand...

Offsetting the target is exactly what is done directly in IMFD. Using flytandem's scenario, (and turning off the atmosphere, to avoid orbital decay) I found both a retrograde and a prograde TLI solution to Brighton Beach within the same orbit as the scenario started with. (Even Lunar Transfer MFD finds only one solution.) I too "sculpted" these solutions through variable iteration in IMFD; there was no automatic button to do so for me.

Retrograde:
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  XPDR 494
END
GL-01:DeltaGlider
  STATUS Orbiting Earth
  RPOS 5592942.26 -302024.83 3253134.75
  RVEL -3889.880 907.289 6763.717
  AROT 41.19 57.80 64.97
  VROT -0.02 0.10 0.11
  AFCMODE 7
  PRPLEVEL 0:0.548374 1:0.981138
  NAVFREQ 402 94 0 0
  XPDR 0
  RCOVER 1 1.0000
  RADIATOR 1 1.0000
  TRIM 0.374110
  AAP 0:0 0:0 0:0
END
SH-02:ShuttleA
  STATUS Landed Earth
  POS -80.6745292 28.5197208
  HEADING 100.00
  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

I tried both of these and in both case got to a 120km circular lunar orbit that passed within just 20km of Brighton Beach on the first pass without the need for any mid-course correction whatsoever.
If the delta-v in these cases is higher than in the transX solution, it is because of the 5 degree inclination from the lunar plane, which in my view is unnecessary. With IMFD, you can launch into the lunar plane and get a same-day TLI because you can visualize an immediate offset. On the left side you can see in three dimensions how your theoretical 2-body transfer ellipse is going to be offset from the center of the moon. On the right side, in real time, you can see how your changes in the offset will affect the full 3-body trajectory from the earth to the moon. What better visualization is there? Frankly, I find an arbitrary plane misalignment that will work at some undetermined time in the future to be much more difficult to understand.
 
I don't think that the tool that you use to make the flight really matters, as long as you can visualize what's going on and understand the basic concepts behind it.

I am fluent in both TransX and IMFD and I find that they complement each other very well. Learning how to use both has helped me achieve any goal I have set for myself in Orbiter, as long as there is enough Δv.

On the topic of setting up a flight to land on a specific target on the moon, this essay was great in helping understand what's going on, and which parameters limit the launch windows and landing sites.

Over the past couple of weeks, I've been investigating different ways to go to the moon and I have found 3 different ways, using minimum Δv.

1. The traditional method. "Transfer - LOI - Landing".
2. The Direct landing method. "Transfer - Landing".
3. The Belbruno-Miller transfer. "Transfer - Lunar Orbit without LOI burn - Landing".

Using the "traditional" method, the offset of a tranfer for a "direct over the base" flight, leads to a slightly higher velocity at lunar periapsis and thus, almost cancels out any Δv saved from not having to perform MCCs.

In order to save Δv, it's always better to launch as close as possible to a moon coplanar orbit and set up an intercept at the apoapsis of the moon's orbit around the Earth. This leads to a low intercept velocity, so you need less Δv for the LOI burn. The base alignment burn always happens well outside the Moon's (strong) SOI (G 0.12-0.14) and doesn't cost more than 40-50 m/s. (Long and Lat of base are irrelevant). The downside of this method is that the initial transfer is not a free return trajectory.

A non traditional way is the Direct landing method. You start with a coplanar transfer aiming exactly for the center of the Moon and make the neccessary corrections to keep the eccentricity of the intercept orbit to 1. Then you turn the ship retrograde and fire the engines at the correct altitude, in order to reach 0 vertical vel. at ~0 alt.
This saves ~100 m/s than the traditional method as long as your ship can provide a deccelaration higher than 25 m/s². The higher the deccelaration the more the savings, because you spend less burn time inside the lunar gravity well.
The downside of this method that your landing sites are limited inside an area with a radius of about 200 km. (Green circle in the pic below. The yellow square in the North, is the location of Brighton Beach).
moon.jpg


The third way is the Belbruno-Miller transfer. Basically you make a transfer to the Moon and sling past it, to an orbit with an apoapsis almost at the edge of Earth's gravity well and a periapsis at the height of the Moon's orbit. Timing it correctly, leads to a low intercept velocity (300 to 400 m/s) instead of the traditional (800-900 m/s). So you get in a lunar orbit without a LOI burn.
The downside of this method is that the flight-time is much longer. (+60 days). Below is a pic of an attempt of such a trajectory in Orbiter (Middle MFD).
BMtransfer2.jpg


If you have tried flytandem's Polar to GEO challenge, then it's pretty much the same thing, just a little bit more extreme.

Hope this post helps.
:cheers:
 
Last edited:
Dgatsoulis, that Apollo article was a great read. I understand better how flytandem was using the out of plane orbit.

So, if I understand correctly, Apollo used an out-of plane but mostly prograde TLI and then made a plane change for landing point alignment during LOI, which is exactly opposite of how I am doing it. This was to maintain a free return trajectory, and also because not having an in-plane launch allowed for a 2.5 hour, rather than instantaneous launch window.

There is no weather in Orbiter ;) we don't need long launch windows so launching in-plane I think is the way to go. Nor do we need to be confined to free return. The original question was how to make the ejection burn with inclination change, so that you arrive on the Moon, passing over the required base already, with no inclination burn on SOI required. With a traditional approach, this is certainly possible and I think the best way to go is by offsetting the moon at TLI, which I demonstrated in IMFD.
 
boogabooga said:
So, if I understand correctly, Apollo used an out-of plane but mostly prograde TLI and then made a plane change for landing point alignment during LOI, which is exactly opposite of how I am doing it. This was to maintain a free return trajectory, and also because not having an in-plane launch allowed for a 2.5 hour, rather than instantaneous launch window.
Click to expand...

Yes, that's pretty much it. There were many restrictions: flight time, free return trajectory, long launch windows to overcome weather issues and so on. In a sense it wasn't the spacecrafts that chose the landing sites, rather the landing sites chose the spacecrafts+restrictions.

The original question was how to make the ejection burn with inclination change, so that you arrive on the Moon, passing over the required base already, with no inclination burn on SOI required. With a traditional approach, this is certainly possible and I think the best way to go is by offsetting the moon at TLI, which I demonstrated in IMFD.
Click to expand...

It's a nice and elegant way to do it, I use it myself quite often.
But the OP also mentioned potential Δv savings from flying to the moon this way instead of the usual.

What I have found is that the increased intercept velocity at the Lunar Pe, leads to a more expensive LOI burn, which almost cancels out any benefits of not having to perform the MCC for the base alignment.

In IMFD starting from a coplanar orbit, you need to mix the plane change in your prograde burn, in order to offset and you end up using more Δv. And -same as an offplane burn- you also reach moon periapsis at high velocity.

It really depends on what your goal is. If you want to make a "single burn to Brighton Beach" flight then the way you've been using is great, because it uses IMFD's superior map program, to let you now where you are, where you will be and how much Δv you'll need. (BTW you can also use the map program with TransX, but only after you've performed the burn.)

If you are a Δv budget freak (like me), you'll see that using this method isn't really any better than performing a base alignment burn.

Just my :2cents:
:cheers:
 
Hmm. I'm not noticing a big difference in cir velocity at lunar Pe.

Do you have Lunar Base Aurora? It's at 28.5 S, so I've used it as an example, instead of the extreme latitude Brighton Beach. Here is the relevant part of the config.

W-Aurora.cfg:
Code: 
BASE-V2.0
Name = Aurora
Location = +42.46 -28.54
Size = 200
ObjectSize = 200
MapObjectsToSphere = TRUE

Here is a scn for a DG in the lunar plane with IMFD TLI setup, no offsets.

Code: 
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51983.0639846748
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01S
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01S
  MODE Cockpit
  FOV 50.00
END_CAMERA

BEGIN_HUD
  TYPE Orbit
  REF AUTO
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target moon
  Center moon
  Data 0 1 1.64328122463323e-005 0 0 0 0 0 1 1 0 0
  MassLimit 1e+020
  CMode 1
  Config 1 1 1 1 800000 0
  ExtMode 2
  Periapis Moon
  END 
  CorMFD V4
  Reference Earth
  Target Moon
  Source GL-01S
  ActiveProg 1 1
  DataA 1 3 0 0 0 0
  DataB 3.375 1 51983.10354121545 0 0 4.932418488553791 0 51986.22222235093 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 51983.05807148456 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.05807148456 51983.05807148456 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source none
  Data 0 1 1 3 0 1 51983.05807148456 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 1
  CF1_DataB 51982.6685767396 10 120000 2 20 150000
  CF1_SecTgt Aurora
  mfdShare -1
  mfdProgram 2
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target moon
  Center moon
  Data 0 1 1.64328122463323e-005 0 0 0 0 0 1 1 0 0
  MassLimit 1e+020
  CMode 1
  Config 1 1 1 1 800000 0
  ExtMode 2
  Periapis Moon
  END 
  CorMFD V4
  Reference Earth
  Target Moon
  Source GL-01S
  ActiveProg 1 1
  DataA 1 3 0 0 0 0
  DataB 3.375 1 51983.10354121545 0 0 4.932418488553791 0 51986.22222235093 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 51983.05807148456 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.05807148456 51983.05807148456 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source none
  Data 0 1 1 3 0 1 51983.05807148456 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 1
  CF1_DataB 51982.6685767396 10 120000 2 20 150000
  CF1_SecTgt Aurora
  mfdShare 0
  mfdProgram 4
END_MFD

BEGIN_VC
END_VC

BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  RPOS 6160328.86 -2703959.11 -524389.16
  RVEL -2757.836 -6714.696 2493.674
  AROT -20.27 -50.93 -162.95
  VROT 0.14 -0.04 0.06
  AFCMODE 7
  PRPLEVEL 0:1.000000
  IDS 0:588 10 1:586 10 2:584 10 3:582 10 4:580 10
  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 5168755.44 -193776.31 -4235482.00
  RVEL 4844.602 428.793 5989.189
  AROT 14.74 -73.72 79.05
  VROT -0.14 0.00 0.00
  AFCMODE 7
  IDS 0:540 100 1:542 100 2:544 100
  XPDR 482
END
Luna-OB1:Wheel
  STATUS Orbiting Moon
  RPOS 2202255.60 405169.19 127.61
  RVEL -267.751 1455.289 0.073
  AROT -0.00 -0.00 107.74
  VROT 0.00 0.00 10.00
  AFCMODE 7
  IDS 0:560 100 1:564 100
  XPDR 494
END
GL-01S:DG-S
  STATUS Orbiting Earth
  RPOS -3525992.11 409486.76 -5466476.98
  RVEL 6550.240 -482.699 -4262.873
  AROT 102.60 -23.32 -127.51
  VROT -0.09 0.01 0.06
  PRPLEVEL 0:0.370139 1:0.989174 2:1.000000
  NAVFREQ 94 524 84 114
  XPDR 0
  RCOVER 1 1.0000
  RADIATOR 1 1.0000
  PSNGR 2 3 4
  TANKCONFIG 1
  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

It starts out with negative PeA.
When I tried this, I used the Base Approach for MCC just outside the lunar SOI and again within the Lunar SOI and needed something like 120m/s. My circ. velocity at lunar Pe was something like 895m/s. Sure, this is higher than if I would have stayed in plane, but from what I have observed, if you must target the base, then circ. velocity is going to increase even if you do MCC closer to the moon.

Here is a setup for an offset TLI directly into an orbit to intersept the base:

Code: 
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51983.0728067580
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL-01S
END_FOCUS

BEGIN_CAMERA
  TARGET GL-01S
  MODE Cockpit
  FOV 50.00
END_CAMERA

BEGIN_HUD
  TYPE Orbit
  REF AUTO
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target moon
  Center moon
  Data 0 1 1.64328122463323e-005 0 0 0 0 0 1 1 0 0
  MassLimit 1e+020
  CMode 1
  Config 1 1 1 1 800000 0
  ExtMode 2
  Periapis Moon
  END 
  CorMFD V4
  Reference Earth
  Target Moon
  Source GL-01S
  ActiveProg 1 1
  DataA 1 5 0 1 0 0
  DataB 194.6195068359375 1 51983.10355278953 0 0 4.93241848855379 0 51986.22222235093 0
  DVProg 0 0 0 1
  AdvConf 6.143558967020042 1.455604596163268 2279141.834453923 2 0
  Guidance 0
  END 
  EjectMFD V5
  Reference Auto
  Data 0 1 3 0 1 51983.05807148456 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.05807148456 51983.05807148456 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source none
  Data 0 1 1 3 0 1 51983.05807148456 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 1
  CF1_DataB 51982.6685767396 10 120000 2 20 150000
  CF1_SecTgt Aurora
  mfdShare -1
  mfdProgram 2
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target moon
  Center moon
  Data 0 1 1.64328122463323e-005 0 0 0 0 0 1 1 0 0
  MassLimit 1e+020
  CMode 1
  Config 1 1 1 1 800000 0
  ExtMode 2
  Periapis Moon
  END 
  CorMFD V4
  Reference Earth
  Target Moon
  Source GL-01S
  ActiveProg 1 1
  DataA 1 5 0 1 0 0
  DataB 194.6195068359375 1 51983.10355278953 0 0 4.93241848855379 0 51986.22222235093 0
  DVProg 0 0 0 1
  AdvConf 6.143558967020042 1.455604596163268 2279141.834453923 2 0
  Guidance 0
  END 
  EjectMFD V5
  Reference Auto
  Data 0 1 3 0 1 51983.05807148456 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.05807148456 51983.05807148456 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source none
  Data 0 1 1 3 0 1 51983.05807148456 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 1
  CF1_DataB 51982.6685767396 10 120000 2 20 150000
  CF1_SecTgt Aurora
  mfdShare 0
  mfdProgram 4
END_MFD

BEGIN_VC
END_VC

BEGIN_SHIPS
ISS:ProjectAlpha_ISS
  STATUS Orbiting Earth
  RPOS 2130123.95 -6239417.40 1333193.31
  RVEL -7146.742 -1963.803 2069.423
  AROT -72.17 55.06 -133.03
  VROT 0.13 -0.06 -0.03
  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 6505413.57 163910.47 1306157.11
  RVEL -1593.489 446.408 7593.512
  AROT 2.66 23.63 87.05
  VROT -0.13 -0.00 0.00
  AFCMODE 7
  IDS 0:540 100 1:542 100 2:544 100
  XPDR 482
END
Luna-OB1:Wheel
  STATUS Orbiting Moon
  RPOS 1733183.90 1417797.95 169.40
  RVEL -936.909 1145.320 0.034
  AROT 0.00 0.00 170.01
  VROT -0.00 -0.00 10.00
  AFCMODE 7
  IDS 0:560 100 1:564 100
  XPDR 494
END
GL-01S:DG-S
  STATUS Orbiting Earth
  RPOS 2174335.86 -66461.22 -6148910.32
  RVEL 7349.452 -677.425 2595.920
  AROT -85.80 -48.37 120.27
  VROT -0.16 0.00 0.03
  AFCMODE 7
  PRPLEVEL 0:0.370139 1:0.989174 2:1.000000
  NAVFREQ 94 524 84 114
  XPDR 0
  RCOVER 1 1.0000
  RADIATOR 1 1.0000
  PSNGR 2 3 4
  TANKCONFIG 1
  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

For the same flight time, this adds about 20-30 m/s to TLI. Notice that cir is 903m/s, or 8m/s more.

So, as far as I can tell, the offset at TLI (second scenario) procedure will be more efficient if you can't keep the MCCs of the usual procedure (first scenario) under 30- 40ish m/s, which I have not been able to do.

(just noticed that I was using realtime instead of off-axis in posted scn. I have to test to see if this makes a difference)
 
boogabooga said:
Do you have Lunar Base Aurora? It's at 28.5 S, so I've used it as an example, instead of the extreme latitude Brighton Beach. Here is the relevant part of the config.

W-Aurora.cfg:
Code: 
BASE-V2.0
Name = Aurora
Location = +42.46 -28.54
Size = 200
ObjectSize = 200
MapObjectsToSphere = TRUE
Click to expand...

I don't but I added a copy of BB at those coordinates and named it Aurora.

I haven't had time to try your scenarios but the numbers seem a bit high.

boogabooga said:
It starts out with negative PeA.
When I tried this, I used the Base Approach for MCC just outside the lunar SOI and again within the Lunar SOI and needed something like 120m/s.
Click to expand...
. You probably made the burn too late. Even for BB, I've never had to use more than 50 m/s.

boogabooga said:
My circ. velocity at lunar Pe was something like 895m/s. Sure, this is higher than if I would have stayed in plane, but from what I have observed, if you must target the base, then circ. velocity is going to increase even if you do MCC closer to the moon.
Click to expand...

You could have saved ~90 m/s if you had arranged it so that you reached the Moon at its apoapsis. From a coplanar transfer, the circ. burn is about ~805 m/s for a 50 km alt circular orbit.

I've written a script to help me keep track of my Δv, I'm attaching it here if you want to use it. It gives you info about how much Δv you have used and how much you still have, also your fuel and how much time has passed from the start of the scenario. It's great when you want to keep track of missions and compare them.

The ship has to be a Deltaglider named GL1.
Code: 
BEGIN_SHIPS
GL1:Deltaglider

In order for the Δv counter to work properly you have to set the propelant to these values:
Code: 
PRPLEVEL 0:0.1366028 1:0.03000000

For the weight to be correct you also need to have no passengers.(Delete the "PSNGR 2 3 4" line from the scenario).

This sets you up with 6000 m/s of Δv, more than enough to make the transfer, LOI and landing. Unzip the file in your Orbiter directory and add the line Script Challenges/DG/Direct_landing/Challenge1 after the date between the BEGIN_ENVIRONMENT - END_ENVIRONMENT lines.

Here is an example of how the scenario should be ( I used your first scenario in your last post, deleted the irrelevant ships).

Code: 
BEGIN_DESC
Contains the latest simulation state.
END_DESC

BEGIN_ENVIRONMENT
  System Sol
  Date MJD 51983.0639846748
  Script Challenges/DG/Direct_landing/Challenge1
END_ENVIRONMENT

BEGIN_FOCUS
  Ship GL1
END_FOCUS

BEGIN_CAMERA
  TARGET GL1
  MODE Cockpit
  FOV 50.00
END_CAMERA

BEGIN_HUD
  TYPE Orbit
  REF AUTO
END_HUD

BEGIN_MFD Left
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target moon
  Center moon
  Data 0 1 1.64328122463323e-005 0 0 0 0 0 1 1 0 0
  MassLimit 1e+020
  CMode 1
  Config 1 1 1 1 800000 0
  ExtMode 2
  Periapis Moon
  END 
  CorMFD V4
  Reference Earth
  Target Moon
  Source GL1
  ActiveProg 1 1
  DataA 1 3 0 0 0 0
  DataB 3.375 1 51983.10354121545 0 0 4.932418488553791 0 51986.22222235093 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 51983.05807148456 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.05807148456 51983.05807148456 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source none
  Data 0 1 1 3 0 1 51983.05807148456 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 1
  CF1_DataB 51982.6685767396 10 120000 2 20 150000
  CF1_SecTgt Aurora
  mfdShare -1
  mfdProgram 2
END_MFD

BEGIN_MFD Right
  TYPE User
  MODE Interplanetary
  Scenario Old2
  MapMFD V5
  Reference Auto
  Target moon
  Center moon
  Data 0 1 1.64328122463323e-005 0 0 0 0 0 1 1 0 0
  MassLimit 1e+020
  CMode 1
  Config 1 1 1 1 800000 0
  ExtMode 2
  Periapis Moon
  END 
  CorMFD V4
  Reference Earth
  Target Moon
  Source GL1
  ActiveProg 1 1
  DataA 1 3 0 0 0 0
  DataB 3.375 1 51983.10354121545 0 0 4.932418488553791 0 51986.22222235093 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 51983.05807148456 10
  Guidance 0
  END 
  BaseAprMFD V2
  Reference Auto
  Target none
  Source none
  DataA 0 0 120000 0.10821 0.366519 1 1 51983.05807148456 51983.05807148456 0
  DataB 0 3 0 1 0 1
  END 
  SlingMFD V4
  Reference Auto
  Source none
  Data 0 1 1 3 0 1 51983.05807148456 0
  END 
  LaunchMFD V4
  Target None
  Data 0 1 1 3 0 1 0
  END 
  CF1_DataA 0 1
  CF1_DataB 51982.6685767396 10 120000 2 20 150000
  CF1_SecTgt Aurora
  mfdShare 0
  mfdProgram 4
END_MFD

BEGIN_VC
END_VC

BEGIN_SHIPS
GL1:Deltaglider
  STATUS Orbiting Earth
  RPOS -3525992.11 409486.76 -5466476.98
  RVEL 6550.240 -482.699 -4262.873
  AROT 102.60 -23.32 -127.51
  VROT -0.09 0.01 0.06
  PRPLEVEL 0:0.370139 1:0.989174 2:1.000000
  NAVFREQ 94 524 84 114
  XPDR 0
END
END_SHIPS

BEGIN_ExtMFD
END
Unzip the file in your Orbiter directory and it should go in it's place.

I'll try your scenarios and compare the Δv expenditure to a couple of mine for a landing at the coordinates you provided.
:cheers:
 

Attachments

I completed a test run so we can compare results for a coplanar transfer. As a starting point I used the first scenario you posted. The first thing I noticed was that it wasn't exactly in plane with the Moon, but a 0.17° R.Inc. wouldn't lead to too much trouble, so I kept it as it was. (I prefer my launches with < 0.05° R.Inc.)

The initial burn was 3147 m/s prograde with a tiny amount of inward (7m/s), to adjust my PeA to ~50km. Including spacecraft orientation and a slight adjustment, I ended up using 3148.44 m/s for a transfer that leads to a 6km PeA at the Moon. (Pic1 Pre-burn, pic2 post-burn).


I coasted until I was outside Earth's SOI, oriented the spacecraft in a prograde relative to the Moon direction and performed small linear RCS burns to start minimizing my R.inc relative to the base and push the node to my direction. Repeated the process at the node. (Pics 3, 4 and 5). In total, I used 29.44 m/s to get a R.inc of -0.15° to the base, with a PeA alt of ~2km


Then I setup a BaseApproach burn (orbit-insert), for a PeA of 2km. Total cost was 6.82 m/s. The LOI burn would cost 811.6 m/s (pics 6 and 7)

600 km away from the base, I had used a total of 3996.74 m/s and all I needed was a good landing. I performed a manual "tail-sitter" one, using my hover engines, with a cost of 1873.26 m/s (Pics 8 and 9)


Total Δv from scenario start to landing: 5870 m/s

So to sum up the results:
As I said in my previous posts, the offset transfer leads to a high PeA velocity that cancels any benefits of not having to perform MCCs for base alignment. In this example, even if we count the spacecraft orientation Δv, I used ~100m/s less than the 2nd scenario you posted. The real question is: Does it really matter?

Depends on how you want to fly your missions. A single burn to landing is cool if that's your goal.

Saving 100 m/s from a well tested and nicely flown mission, is mine. (Δv freak)

:cheers:
 
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