How do I reach a Polar Orbit?

[CaptainApollo]

Hello everyone! I want to explore Kerbin's poles, but for that I would need a polar orbit, and I am having a bit of trouble with that. How do I achieve a polar orbit? I have heard that there are a few ways, but I would opt for the easiest. Any help is appreciated! Thank you!

[FleshJeb]

When you do your gravity turn, aim for heading 0 or 180. It'll be a little off from perfect because of the rotation of the planet. If you want it closer to perfect, try 355 or 185.

[Snark]

It's pretty much the same as equatorial, it's just that you turn north instead of east after launching.

You actually want it to be very slightly west of north, to compensate for Kerbin's rotation.

That's basically it. You'll need a smidgen more dV than equatorial, so budget for that.

[CaptainApollo]

I was trying to head North, and I always came out of balance and came back to Kerbin, the Prograde vector just gets low.

[G'th]

You're likely turning too fast and too low in the atmosphere.

[CaptainApollo]

Perhaps that is it? What is a good turning point for polar?

[cybersol]

If you can go eastward to orbit in the same rocket, then an early roll maneuver by 90* should make going north more like going east. Either way though, you likely need more control authority to overcome gravity pulling down your nose, which you can increase control using engine gimbals, stabilizer wheels, and control fins.

EDIT: A good turning profile is most of all to be smooth. How fast to turn over depends on TWR and drag, but a decent start is something like 45 degrees(*) at 15km, 22.5* at 30km, and 5* at 40km.

Edited June 12, 2015 by cybersol

[CaptainApollo]

Hm, only have gimbals and control fins for now, I will try to use those then. More fins!

[Ten Key]

Rockets launching into a polar orbit don't benefit from the extra velocity equatorial rockets pick up due to Kerbin's rotation. In fact, not only do they not benefit from Kerbin's rotational velocity, for a 90 degree orbit, you have to spend some energy to get rid of it. A rocket that is borderline for reaching an equatorial low orbit may not have enough oomph ​to reach a polar orbit.

[CaptainApollo]

I added some more things, but I do not want to make it too heavy.

[cybersol]

Did you make it yet? It really shouldn't be that much different than going east except for the muscle memory and the 200-300 extra dv cost from losing Kerbin's spin.

[CaptainApollo]

Not yet, I'll most likely try tomorrow and tell you the results.

[CaptainApollo]

I am still having a lot of trouble, and I was wondering if it is possible to adjust your orbit while in orbit with a maneuver node in order to land on the poles?

[Kryxal]

Yes, but you're going to spend a LOT more delta-v doing it that way ... a good gravity turn will let you launch straight to a northerly heading.

[ajburges]

Yes, but you're going to spend a LOT more delta-v doing it that way ... a good gravity turn will let you launch straight to a northerly heading.

To be more precise, you need 1.414 (closer to 1.5 with potential energy loss) times your orbital velocity without raising Ap first if you burn the hypotenuse vector.

Burning normal will take 1.571 times orbital velocity without loss of potential energy.

A Munar, powered, gravity asist can do the plane change for circa 1.2 km/s. Plus a few hundred to lower Ap after. We'll say .6 times orbital velocity.

Polar launch takes 300 extra dV. That is only .15 orbital velocity!

Edited June 13, 2015 by ajburges

[cybersol]

I suggest you roll over so that the side of your rocket that usually faces east will be facing north (Q or E keys). That will also spin your nav-ball so north is where east would usually be on it. After that, you can just do what you usually would do going east, only now you just happen to be going north.

[ExaltedDuck]

If the trajectory is coming back down for a polar orbit attempt for a vehicle that makes it fine into a standard eastward departure, it sounds like the ascent path isn't taking into account that the planet's rotation is added to that eastward launch but has to be cancelled out for a polar launch (and would have to be overcome for a westward launch). A northward gravity turn is the most efficient path but you might want to turn a little later and/or a little slower than you would for an eastward ascent, and if it doesn't work out, add a little more fuel.

[CaptainApollo]

Thanks everyone, but I seem to have found a solution! I sent a probe to the Mun and managed to make it land on the pole! However, it counted the biome as 'Kerbin's Grasslands.'