Difference between revisions of "Tutorial: Advanced Orbiting"

Revision as of 23:29, 5 March 2015

Hohmann transfer

Burn prograde at periapsis (or anywhere if circular) until the apoapsis reaches the desired altitude.

Then, at apoapsis, burn prograde until periapsis is at the desired altitude.

Burning retrograde at these same points will lower your orbit.

Bi-elliptical transfer

The bi-elliptic transfer can be more efficient (but slower) than the Hohmann transfer orbit in some cases (when going from a very tight orbit to a very large one: the ratio must be higher than ~12:1). This is because changes of speed are more efficient at low speeds (and therefore at high altitudes).

• Start by burning prograde (most efficiently at periapsis) until orbit becomes highly elliptical with the apoapsis higher than starting and desired orbits.
• At apoapsis, burn prograde until the periapsis reaches the altitude of your desired orbit.
• Upon reaching periapsis, burn retrograde until your orbit is circularized.

Opposite burns at these same points will lower your orbit. This can be used to enable aerobraking to lower your orbit height.

Orbital plane alignment

The first step in intercepting another orbiting body is to align your orbital plane with the target's orbital plane.

Next is to find the pivot point on your orbit that, when turned clockwise or counterclockwise (from the perspective of camera > ship > orbited object), will cause it to line up with the other orbit.

Next, find the midpoint between your prograde and retrograde motion on the horizon and point your ship toward it. Throttling prograde + 90 degrees on the horizon will cause your orbit to rotate clockwise. Prograde - 90 degrees on the horizon will rotate the orbit counterclockwise. It may take a few rotation sessions to perfect your orbit but this will allow you to match another orbital plane.

It is easier to achieve if your orbit is circular, mostly because you can line up the orbits in the map view much more easily.

Orbit synchronization

In progress.

The Exley maneuver

(As of 0.17.1)

A demonstration using a target planet with an orbit outside your starting planet's orbit.

In order to easily meet with a target planet's sphere of influence, you will need to perform a few burns while at either the periapsis or apoapsis of your transfer orbit.

Planets outside your original orbit

If you are meeting with a planet whose orbit is outside of your starting orbit, create a transfer orbit such that your apoapsis is as close as possible to your target planet's orbit.

Next, make a few orbits until the target planet is slightly in front of you when you reach your apoapsis. Begin a prograde burn until you see your orbit cross the target planet's near your apoapsis for a fraction of a second. If you overshoot, simply turn around and burn retrograde until the cross orbit is visible again. If your transfer orbit exceeds the planet's orbit, then you have gone too far, and have either missed the cross orbit, or do not have an apoapsis close enough to the target orbit to be affected by the planet's sphere of influence.

Planets inside your original orbit

If you are meeting with a planet whose orbit is inside of your starting orbit, create a transfer orbit such that your periapsis is as close as possible to your target planet's orbit.

Next, make a few orbits until the target planet is slightly behind you when you reach your periapsis. Begin a retrograde burn until you see your orbit cross the target planet's near your periapsis for a fraction of a second. If you overshoot, simply turn around and burn prograde until the cross orbit is visible again. If your transfer orbit goes within the planet's orbit, then you have gone too far, and have either missed the cross orbit, or do not have a periapsis close enough to the target orbit to be affected by the planet's sphere of influence.

Finally

Once you are in the cross orbit, burn retrograde until the orbit goes around your target planet.

Good luck!