How do I circulize or stabilize my orbit?

[razgriz31m]

I've been playing orbiter soo long now, but still can't figure how to circulize my orbit, so what happens is when i launch and got into space, I will reenter an couple of minutes later, help me!!!:sorry:

 

[MJR]

Raise your PeA past 125km. What are you using becasuse there are different methods for getting into orbit. I can finally make an circular orbit with using the given fuel for shuttle fleet and perform the right manevers. So if you need more in depth help, ask.

 

[razgriz31m]

well, thanks, this sounds stupid but i really don't know how to work on mfd's, I've been practicing on the vostok, i really need a step by step instuction since i only know very few of the terms, like AoA w/c means angle of attack and.....that's only what i know.i'm stupid.help me!!

 

[MJR]

You are not stupid.

1. You first want to launch properly.

2. Download shuttle fleet and watch carefully how the autopilot works and the manevers it performs.

3. Watch your vertical speed when you are getting ready to complete your orbit. If it is too high, then on the OrbitMFD it will have an uneven circle, so maintain it. If you want to decrease the vertical speed of your craft, right after press to MECO, pitch to zero. If you want to increase it, pitch to about 35 degrees.

4 If all went well then it should be pretty circualar and you might have to perfrom another quick burn to ensre that your orbit it a success. Make sure that your PeA is past 125km, and you ApA is around a reasonable amount of 360km. You probably won't get it the first couple times but with practice you will.

Good luck! If you got more questions, ask me step by step when you are actually playing it in windows mode.

 

[RAF92_Moser]

Oh, man. There is so much to learn but it's totally possible. I say go over the checklists in Orbiter and go over some fundamentals.

1. To raise periapsis...burn prograde at apoapsis. To lower periapsis, burn retrograde at apoapsis.

2. To raise apoapsis...burn prograde at periapsis. To lower apoapsis, burn retrograde at periapsis.

 

[MJR]

Eventually you are going to have to launch, orbit, align planes, and sync orbit. Finally you will need to rendezvous. It may seem impossible now but that is what I thought about three months ago. Now I got the hang of it.

 

[razgriz31m]

seems like i need a science dictionary,snap

 

[MJR]

If you look around the forum, sometimes you discover new words and if you use context clues on what is happening, you will know what that word is. That is what I did.

 

[razgriz31m]

oh ok! i'm gonna try that, BTW, this is one of the most nicest forum i've been too thanks

 

[tony]

As long as you are above the atmosphere, you can circularize your orbit with: towards (aim straight at the ground), away (180 degrees from towards), prograde or retrograde burns:

If you are at apoapsis, burn prograde until your eccentricity is 0.
If you are at periapsis, burn retrograde until your eccentricity is 0.
If you are past apoapsis, dropping to periapsis, burn away until your eccentricity is 0.
If you are past periapsis, rising to apoapsis, burn towards until your eccentricity is 0.

The key here is get your eccentricity to 0. Then you're in a circular orbit.
If you're confused, aim any direction and burn. If your eccentricity increases, fire retro rockets instead (or turn 180 degrees and burn). Keep doing this until you've got your ecc as low as possible.

This will give you a good feel for orbits, and eventually you'll learn to get more efficient. For example: from launch, keep burning until your apoapsis equals your desired circular orbit. Then kill thrust and coast to apoapsis. Turn prograde and burn until your eccentricity is 0.

 

[razgriz31m]

hmmmm....can't understand a thing, is there any mfd that can do that automatically?

 

[Urwumpe]

hmmmm....can't understand a thing, is there any mfd that can do that automatically?

IMFD can do that. But if you can't understand the basics behind a Hohmann transfer, you are very likely not enjoying Orbiter for long. What is so hard to understand the relation between the direction and point of the Orbit, where you burn, and the resulting change of the orbit? You have only 4 possible combinations for these basic maneuvers.

 

[FordPrefect]

hmmmm....can't understand a thing, is there any mfd that can do that automatically?

Where's the fun in that?

I propose it's time for you to learn some orbital mechanics! Get yourself a cup of tea and read e.g. here:


http://www2.jpl.nasa.gov/basics/bsf3-4.html

 

[razgriz31m]

hmmm...maybe because i still don't know what apoapsis, periapsis and eccentricity means?

 

[FordPrefect]

hmmm...maybe because i still don't know what apoapsis, periapsis and eccentricity means?

You might take another look at my previous post *hint hint nudge nudge*

 

[Urwumpe]

hmmm...maybe because i still don't know what apoapsis, periapsis and eccentricity means?

Then learn. Quickly. :lol:

Apoapsis = the point of the orbit, which is furthest away from the center of the central body.
Periapsis = the point of the orbit, which is closest to the center of the central body
Eccentricity = measure of the difference between apoapsis distance and periapsis distance. Eccentricity = 0 means, apoapsis and periapsis have the same distance to the center of the central body, it is a circular orbit.

When Ecc approaches 1, the orbit gets more and more distorted into an ellipse. When Ecc becomes 1, the orbit is exactly so distorted, that the spacecraft will travel slowly towards the apogee, but never reach it before infinity. It is now an parabolic orbit (does not exist in reality).
When Ecc is larger than one, the spacecraft has enough energy to leave the gravity and have some speed left. The orbit is now an hyperbolic orbit and the excess speed is called hyperbolic excess velocity.

 

[razgriz31m]

oh....is it the apogee and perigee?

 

[FordPrefect]

oh....is it the apogee and perigee?

Periapsis and apoapsis are generic terms. The prefixes "peri-" and "ap-" are commonly applied to the Greek or Roman names of the bodies which are being orbited. For example, look for perigee and apogee at Earth, perijove and apojove at Jupiter, periselene and apselene or perilune and apolune in lunar orbit, perichron and apochron if you're orbiting Saturn, and perihelion and aphelion if you're orbiting the sun, and so on.

 

[Urwumpe]

oh....is it the apogee and perigee?

Apogee is the apoapsis of an orbit around Earth ("Gaea")
Perigee is the periapsis of an orbit around Earth.

The same with apo/peri-lune (around the moon), etc.

 

[razgriz31m]

oh....i can get an idea now but maybe I'll learn if i can watch the mfd do the work for the mean time, BTW what is that MFD? any links?