Problem Flight plan to L4 and L5

[wingnut]

I haven't used the offset option that much, but as far as I understand it it's the black line. Keep in mind that the orbit is not circular and the difference of the green and yellow lines to the black line is only a Moon radius (~0.45% of the SMa).

The tangent of the moon is at 90° angle to the SMa line. -30° gets you at a 60° angle.

Thank you, now I got it.

Still ~23 thousand km away from the L4. Not bad but not that good either.
Try another run like this:
Wait until the Moon is 45° away from apoapsis and this time use the Rad from Orbit MFD (instead of the SMa) as the value for the Rad in IMFD's offset.
It should get you closer.

I'll try that.
The Rad value in Orbit MFD is the distance from Earth's center to the Moon's center (if Earth is set as reference) and "Wait until the Moon is 45° away from apoapsis" would mean a true anomaly of 225°, wouldn't it?

 

[dgatsoulis]

I'll try that.
The Rad value in Orbit MFD is the distance from Earth's center to the Moon's center (if Earth is set as reference) and "Wait until the Moon is 45° away from apoapsis" would mean a true anomaly of 225°, wouldn't it?

I should have clarified. 45° before apoapsis. So TrA = 135°.

Now that I think about it, this wouldn't work very well. A trajectory with LEO as periapsis and the Moon's orbit as apoapsis takes about 5 days to reach apoapsis.
During that time the Moon travels 5/27.32 * 360° ≈ 66°.
Let's divide that in half, so make a note of the Rad when the Moon is at TrA = 180°-33° = 147°
Follow the same procedure with these variables:

Long = -30
Rad = (Rad when TrA of Moon is 147°)

So you make the burn when the Moon is 33° before its apoapsis and you arrive at your apoapsis when the Moon is 33° after its apoapsis, 60 degrees ahead from it with an offset distance equal to the Rad the Moon has relative to Earth. (The Rad at TrA 147° and TrA 213° should be roughly the same).

 

[Mandella]

The biggest pain in my primary "Playground" system is transiting between the Moon and the L4 and L5 colonies I have in place. The Moon's gravity really makes a mess of the equation, and I always have to seat of my pants fudge the values to make the trip, at great fuel inefficiency. Yes, I could just swing way out or inward towards the Earth, but I like the trip time to be measured in days and not weeks.

Interestingly, I remember some scientist making that very critique of O'Neil's suggested placement of colonies at L4 or L5. Since the plan depended on using lunar materials to build the colonies he suggested that perhaps the stations should be placed in a more delta-v friendly orbit. He put forth a 2 to 1 resonance orbit between Earth and Moon that would precess with the Moon's orbit, giving a low energy transfer point twice a month for materials to be shot to an intercept.

I'd love to see such an orbit modeled in Orbiter, but I suspect it would need a .dll to stay stable.