Most efficient inclination changes

[dave4002000]

Here's something that's been bugging me for a while because i'm not quite sure i'm doing this as efficiently as possible. My usual approach to a polar orbit around an atmo planet is as follows:

- Aerobrake on an approximate 0° inclination which sets up an elliptical orbit

- Travel to Ap and raise Pe to desired height

- Change inclination at the next closest AN/DN

- Travel to Pe and circularize

Is that the best way it can be done or are there some other tricks that i'm not using? Is there any advantage/disadvantage to aerobraking at 0° or should i adjust my inclination right at SoI change?

Edited July 16, 2013 by dave4002000

[stupid_chris]

Adjusting your angle at the SOI change can be very tricky if you're far from your AN or DN. I usually leave myself in a wide orbit, go to the furthest AN/DN, change the orientation, raise my periapsis to do a slight aerobrake setting my apoapsis at the height I want it then circularize out at the apoapsis.

[rryy]

You can try to adjust your inclination in solar orbit long before your encounter, but if you mess up the inclination, you will need to waste a lot of delta-v to correct.

[bsalis]

Inclination changes are most efficient at slower velocities.

So ideally, you do them at the AN or DN that is near the Ap in a highly elliptical orbit.

[dave4002000]

Thanks for the answers everyone

Inclination changes are most efficient at slower velocities.

So ideally, you do them at the AN or DN that is near the Ap in a highly elliptical orbit.

I think that pretty much sums up what i was asking and also confirms what i'm doing. I aerobrake just enough to capture and let my Ap run as wide as possible (if i need a big inclination change, anyway).

rryy, i'll try that next time i'm heading out to Duna. I'm not sure how well i'll be able to pull it off, but it should be entertaining to say the least..haha

[tomf]

If you are aiming for a polar orbit the best way is to use a conics_mode 0 and a maneuver node well before your encounter to set the projected PE at either the south or north poll of the target. Aiming for the poles from well outside the SOi is very cheap and if you can aerobrake there then you will fall into a polar orbit for free.

[KerbMav]

If you are using the enhanced nodes mod you might want to try out the cones set to 0 and focus your view at your target body.

Zooming and rotating your view so you can see your node-cross-pull-thingies and your encounter orbit at your target body.

Pro and Retro wont help that much, but the other four directions can give you a gravity assist that may change your orbit to a more desirable one - as well as an aerobreaking flight path (if you are good at it, I usually dont feel the atmosphere really and shoot right through it or end up landing ...).

Burning precisely while still far far away is nearly impossible though, as even tiny changes to your flight path (rotating with RCS or just torque even, or just the wobble during the burn) can end up changing your course by several thousand or tens of thousand meters depending on the distance from the target. But burning this far away is really cheap (dv / fuel) and any deviations can be corrected when the vessel is closer to the target.

(so it took me 22 minutes longer than tomf to type and post - I work to much while in the office it seems! )

[dave4002000]

I didn't even think to try a different conics mode. I've just gotten so used to using mode 3 lately, i completely forgot it can still be changed..haha. I"ll give that shot, too. Thanks for the tip.

[Mr Shifty]

I believe (and maybe my thinking is flawed this morning; haven't had coffee yet) you can always get to a polar orbit (or at least an orbit that passes over the poles) by doing your inclination change at apoapsis, i.e you don't need to be at AN/DN. (Equatorial orbits are harder because you want the whole orbit over zero latitude; for polar orbits you don't care what the longitudes are.) Get into the planet's SOI, do a burn at Pe just enough make the orbit elliptical, coast to Ap, change inclination to polar, back to Pe to circularize.

Edited July 16, 2013 by Mr Shifty

[magnemoe]

Here's something that's been bugging me for a while because i'm not quite sure i'm doing this as efficiently as possible. My usual approach to a polar orbit around an atmo planet is as follows:

- Aerobrake on an approximate 0° inclination which sets up an elliptical orbit

- Travel to Ap and raise Pe to desired height

- Change inclination at the next closest AN/DN

- Travel to Pe and circularize

Is that the best way it can be done or are there some other tricks that i'm not using? Is there any advantage/disadvantage to aerobraking at 0° or should i adjust my inclination right at SoI change?

Why don't you come inn for aerobrake over the poles? at 3-4 the distance to the SOI, I adjust my path so it will get inn over the north pole, once I enter the SOI, I do fine adjustments for aerobrake to put me in an fitting approach, this will put you in an polar orbit, check the path from time to time as you warp towards target, circulate after aerobrake.

This is no different from getting into equator orbit.