Inefficient inclination burn?

[ToukieToucan]

So, I need to launch a satellite in a specific orbit:

Apo - 5 408 688

Peri - 965 842

inclination - 171

Long. of AN - 68.8

Arg. of Peri - 114,6

Now I am in an orbit around kerbin of about 100 km and I noticed when I burned at the normal node it took a lot of fuel to go from around 0 degrees of inclination to 10 degrees and that it takes a long time.

Should I increase the inclination while in the atmosphere of when I am at my apoapis (or something else) ?

Edited September 6, 2015 by ToukieToucan

[cantab]

The slower you're moving the less delta-v a plane change needs. The higher you are the slower you're moving.

And keep in mind a 170 degree inclination means orbiting retrograde. It's most fuel-efficient to launch into the inclination you want, which you do by waiting until KSC is underneath the target orbit then pitching over in the right direction during your ascent. If you did a common launch to a 0 degree inclination then in your case you will need to pretty much stop dead and start going the other way. Even 5 thousand km up that's going to need a decent chunk of delta-V.

Edited September 6, 2015 by cantab

[Starhawk]

Hello ToukieToucan, and welcome to the forums!

Inclination changes are very expensive in terms of delta-v.

The best plan to match the inclination required is to launch into that inclination, or close to it.

In this case, you want to launch to the West rather than to the East, since that would give you an inclination of 180 degrees. It should then be fairly easy to adjust to match the required orbit.

Hope this helps.

Happy landings!

[ToukieToucan]

Hello ToukieToucan, and welcome to the forums!

Inclination changes are very expensive in terms of delta-v.

The best plan to match the inclination required is to launch into that inclination, or close to it.

In this case, you want to launch to the West rather than to the East, since that would give you an inclination of 180 degrees. It should then be fairly easy to adjust to match the required orbit.

Hope this helps.

Happy landings!

Thanks, though how do I know I'm going east? Going to the left of doesnt directly mean going east right?

[Clipperride]

It's often the inclination of the desired orbit that constrain NASA to such precise launch windows. It's also why none of the Apollo landing sites are far from the Moons equator. KSP makes it easier to Launch at any time and sort out the orbit later (with plentiful resources). But it's always going to be expensive in terms of fuel to make major changes to inclination from a burn.

[Ripper2900]

Thanks, though how do I know I'm going east? Going to the left of doesnt directly mean going east right?

Use the nav ball. It has bearings written on it's "equator". 0 is north, 90 East, 180 south, 270 West.

In your case, you would want to launch westwards, towards 280. (east minus 170)

[ToukieToucan]

Use the nav ball. It has bearings written on it's "equator". 0 is north, 90 East, 180 south, 270 West.

In your case, you would want to launch westwards, towards 280. (east minus 170)

Thanks, that worked very well.

[ToukieToucan]

Use the nav ball. It has bearings written on it's "equator". 0 is north, 90 East, 180 south, 270 West.

In your case, you would want to launch westwards, towards 280. (east minus 170)

One more question how do I edit the argument of peri without using a lot of fuel and messing up other things like apo and peri height?

[Kryxal]

I'd say get it right the first time, eyeball the orbit on the map ... place your maneuver node and make sure the orbits match as to AP, PE, placement of those two (gives you argument of) and inclination.

[Ripper2900]

Once you're in low kerbin orbit and pretty circularised, withe right inclination, put a maneuver node and drag to get it to the height of the target apoapsis. Then drag it along your orbit until the position of the node apoapsis is at the correct target apoapsis. Do the burn, and repeat the procedure for the periapsis.

Then you should have the correct orbit

[severedsolo]

One more question how do I edit the argument of peri without using a lot of fuel and messing up other things like apo and peri height?

If you launch into the orbital inclination that Ripper already gave you, as KSC crosses the orbit line, your argument of periapsis will be (more or less) already there.

[Sharpy]

A thing of note: if you are already in orbit and need to make a major inclination change, your best bet is to increase your apoapsis to nearly the edge of SOI, perform the inclination change there, and then airbrake back to desired orbit.

For argument of periapsis: actually, set the argument of apoapsis Start with a circular orbit of desired inclination and radius of the desired periapsis, and perform the burn raising the apoapsis with node placed at the point of argument of periapsis. (alternatively, start with circular of radius of apoapsis and burn retrograde 180 degrees from desired argument of periapsis).