Navball surface mode vs orbit mode

[kiwiak]

So, i noticed that during ascent, my markers suddenly change position a little, thats probably surface and orbit mode switch i heard of.

How does it work?

[Kasuha]

Probably the best description is on the Wiki.

[Procyon]

There are 3 modes surface / orbit / and target on is your speed relative to the surface of the body you are over. one is orbital speed. and the third is speed relitive to a target you have selected. The modes switch automatically at certain distances but you can switch manually by clicking on the green field the speed is indicated in.

[adinfinitum]

It just changes the frame of reference that your velocity is determined from. Surface mode shows you your velocity relative to the surface of the body you are orbiting, while orbit mode calculates it relative to the center of the body you are orbiting.

Because all the planets and moons rotate, you have a non-zero orbital velocity when you are stationary on the surface. On the surface of Kerbin, you are moving about 175 m/s relative to the center. If you switch the mode from surface to orbit while on the launch pad, it'll show you that velocity. Because that eastward motion shows up in orbit mode but not in surface mode, the markers showing your heading will change slightly when switching between the modes.

Target mode does something similar, it just sets your target as the reference point for calculating velocity. And if you forget to switch from orbit to surface when landing, you're gonna have a bad time.

[Kryxal]

True, you can have a few bad seconds when you notice the navball is telling you there's not much horizontal velocity, but looking at the ground says otherwise ... worse if you're using the IVA or map view, you don't see that little detail!