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Orbit angles/planes? Not quite sure what they're called.


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Hi! I'm new to the game and have looked at a few of the tutorials, but I have a question about orbit angles - I'm not quite sure that's the right word.

Anyway, a picture is attached to explain. I've tried heading north or south after liftoff, but then am not able to get into orbit. Can anyone please help? Thanks!

http://imgur.com/ISLHoO2

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By taking off to the North or South (0 or 180 on the navball) you should launch into a polar orbit, the vertical orbit in the picture. Launching East or West will put you in an equatorial orbit (90 or 270 on the navball), East being in the direction of the planet's rotation.

Anything in between is a balance between N/S and E/W; launch North-East or South-West for the other orbit you've drawn.

In all cases, the only difference in getting to orbit is the angle at which you're moving relative to the equator. At apoapsis you'll need to circularise by burning in the direction you're moving, which may be where you're going wrong (hard to tell what the problem is, the difference in dV between orbits you launch into is next to nothing) rather than burning East like you would in an equatorial launch. For a polar orbit, launch north, push your orbit out of the atmosphere by continuing northwards, reach the apoapsis and then burn north (or south, if you've passed the pole by that point).

Alternatively you can get into an equatorial orbit and burn North/South to change to one of the orbits you've drawn. However, that's one of the most 'expensive' types of maneuvers you'll ever need to do in this game.

Oh, and the correct term is "Inclination" :)

As is always the case, I'm sure someone can explain it much better than I can, but I hope that helps.

Edited by Epthelyn
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The reason most rockets go east is because it saves an an amount of dV equal to the planets rotation. If you want to get into a polar orbit form the pad you are going to want more dV than you would normally for an equitorial orbit. To get into a polar/highly inclined orbit point that way on the Navball. (North is 0, east is 90 you get the idea)

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That's the "inclination" of the orbit, that you're referring to. If you want to get into a polar orbit, rather than an equatorial orbit, then yes, you'll want to launch to the north or south.

Usually, for an efficient launch to orbit, you'll want to start out flying straight up, and then start a "gravity turn" after an altitude of about 8 or 10km, and gradually arc over, such that you're flying horizontal by the time you're exiting the atmosphere.

For an "equatorial orbit", you'll want to turn to the east, since the planet is rotating that direction, and so you can keep that velocity as a bonus (whereas going west, into a "retrograde orbit", you'll have to negate that velocity and then re-add it in the other direction, costing more fuel).

For a "polar orbit", you can go to either north or south, otherwise the gravity turn should be the same. It will cost slightly more fuel (requiring slightly more delta-V) than going to the east, but not as much as going to the west.

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Chapter 3 of the tutorial in my signature deals with placing SCANSat satellites into orbit. Being mapping satellites these need to go into roughly polar orbits so they 'see' the whole world as it turns beneath them. Sample satellites and launch vehicles are included. Knock yourself out :-)

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Note that to get into a polar orbit you need to launch slightly northwest or southwest with respect to the planet's surface. By default the navball is in surface mode when you launch and doesn't switch into orbit mode until quite late. It can help to switch it manually shortly after your pitchover, and then you can keep prograde aimed due north/south

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