Flight Question My personal Project: Lagrange (building station in Earth's L4 or L5)

[Vanessa85]

Hello to everybody. It is my first post to this board. I really love orbiter and read all the manuals, tested some addons and flew some of the tutorials on youtube to introduce myself to some very nice addons. My favorite until now is my "personal" Island Witeawake and the UCGO, DGIV and XR5. As my native is german, my english speaking is not very good. Please excuse me my mistakes.

I love it to fly and dream while looking to the stars

But now I planned a project for myself: I want to build a really really big station maybe with station building blocks or by docking some ISS to each other. The position of this should be the lagrange points L4 or L5 as these are stable. I read the articles in wikipedia and googled around. But I really have no idea how to calculate or even how to reach this goal.

Also some questions aren't answered in orbiter manual in a pleasing amount.

I divided my project into several parts. If I really manage to be able to fly my scenario, I will write a manual for the community. Maybe one or another will join my station

A: Fly the first recon crew to the moon where the arrow freighter will be build. The mass of the arrow is the amount of cargo which will be delivered to the moon.
-> planning completed; work in progress

B: Fly the arrow freighter to the Lagrange point L4 or L5
-> no meaning how to accomplish that

C: undock the DGIV from arrow and fly back to earth
-> have a theoretical meaning but don't know how to do in orbiter

D: Take an XR5 to fly back to the arrow freighter. But... how to fly to it?
-> No meaning on how to use the mfd to get to other vessels in space

If someone of you can help me on how to configure the right mfd, and most important, which mfd should I use? TranX and interplanetar mfd is far too difficult for me


I also have some other general questions regarding orbiter. Maybe the one or other question can be answered?

1. With standard scenario there is a iss in space. But in this height there is an atmosphere. How can I "push" the ISS to the right orbit if it's periapsis is going too low? Anyway, how long does it take until I need to push the periapsis up?

2. Is the physic simulation quite accurate in fast time motion? Will the orbital path be incorrect with very high values?


I hope, some of you can help me playing around in space.

 

[Urwumpe]

1. With standard scenario there is a iss in space. But in this height there is an atmosphere. How can I "push" the ISS to the right orbit if it's periapsis is going too low? Anyway, how long does it take until I need to push the periapsis up?

By doing a single impulse at the apogee to raise the perigee. Generally speaking, the ISS needs a reboost every 3 months. The lower you get, the faster you will loose altitude.

Important to know: The apoapsis will drop much faster than the periapsis, until the eccentricity is pretty low.

2. Is the physic simulation quite accurate in fast time motion? Will the orbital path be incorrect with very high values?

It gets more inaccurate, the more you accelerate. But up to 100x can be considered fair game. It also depends on your frame rate. the lower your frame rates are, the less accurate Orbiter is.

When inside the atmosphere, even 10x can be far too much, it depends on how strong the aerodynamic forces change by a small change in AOA. I remember tests with a special conical rocket, that even failed to work at 1x (But worked out at 0.1x)

In interplanetary flight 10000 x is no problem the errors by the math in Orbiter don't exceed real world errors by real world factors then.

 

[Tommy]

Getting to a lagrange point isn't easy. There is a way to make it possible, but it requires an add-on: [ame="http://www.orbithangar.com/searchid.php?ID=5033"]Lighthouse (Lagrange point pseudo-planets)[/ame]

It's a bit confusing to set up at first, but I'm sure people here can help if you need. Once you've created the "lighthouse", you can Target the point in MFD's like TransferMFD or AlignMFD, etc. You will still want to learn IMFD or TransX to get to the point. They are confusing, but there's plenty of tutorials for both. I'd recommend IMFD at first - it's easier to use. You can use IMFD's Target Intercept program to get there pretty easy.

The trip back to Earth in the DG can be done easily with IMFD's Base Approach program - or can be done using just OrbitMFD (but is MUCH harder)