Best way to put a satellite in low Kerbol orbit?

[chaos_forge]

Hello, I would like to get some kind of discussion going on to figure out the most delta-v efficient way to put a satellite into low Kerbol orbit. The craft itself would have three stage groups: a chemical engine group for liftoff, LVN for planetary maneuvers, and ion engines for when I'm very close to the sun. I would obviously not want to use the debug menu.

Using normal Hohmann transfer orbits would require me to build a craft with 66 km/s of Delta-v. What I want to know is how low could we get the delta-v by using Bi-elliptic transfers, gravity assists, or maybe even other things I haven't thought of. Which planet would be best for gravity assists? Moho because it's closer, or Eve because it's not inclined? Or maybe another planet?

I dunno, guys. Does anyone have any advice?

Edited August 28, 2013 by chaos_forge

[Sirine]

Is a 1 shot launch or multiple launch?

Edited August 28, 2013 by Sirine
Yes I'm hungry. :)

[chaos_forge]

Is a 1 shot lunch or multiple lunch?

Hmm, hadn't thought about that . . .

I'd say docking is allowed in Kerbin orbit, but once you leave Kerbin orbit, you're on your own.

[capi3101]

Let's start with the basics: how massive is your payload and what is your final desired orbital altitude?

[Sirine]

So, where u wanna send your satellite?

[chaos_forge]

Let's start with the basics: how massive is your payload and what is your final desired orbital altitude?

A probe core + one static solar panel + one communotron is enough. As for target altitude, I was thinking something ridiculous like 500km.

EDIT: also, I'm looking for a relatively circular orbit. No point having a periapsis at 500km if the apoapsis is at 5,000,000km

Edited August 28, 2013 by chaos_forge

[Sirine]

Circular orbit? 500,000m?

[Sirine]

I will say... 100 units of fuel is sufficient. (for sending a satellite you mention to HKO 500km, circular orbit)

[chaos_forge]

Circular orbit? 500,000m?

Yes. Well, it doesn't have to be perfectly circular, but enough so it doesn't look obviously elliptical.

EDIT:

I will say... 100 units of fuel is sufficient. (for sending a satellite you mention to HKO 500km, circular orbit)

Okay, but by how much can I reduce through use of orbital techniques? I'm trying to avoid a "MOAR BOOSTERS" approach.

Edited August 28, 2013 by chaos_forge

[Sirine]

I really not understand... orbital techniques? There are none. (for sending a satellite to High Kerbin Orbit 500km, circular orbit.)

and 100 DeltaV is already extreme/

[NGTOne]

You could probably aerobrake (corona-brake?) in Kerbol's "atmosphere", though you'd likely need to use MechJeb to figure out where your periapsis would be after the maneuver. And you might need to make more than one pass.

[UmbralRaptor]

I'd lean towards (in order of decreasing potential ÃŽâ€V savings): An Eve sling, a Jool Sling, or an old-school bielliptic sundive (arbitrarily high apastron, followed by burning to lower you periastron). Circularization ÃŽâ€V (at 500 km altitude) would be somewhat under 27.7 km/s, depending on your apastron. Transfer ÃŽâ€V would be ~1 - 5 km/s from LKO, depending on method and efficiency.

[chaos_forge]

I'd lean towards (in order of decreasing potential ÃŽâ€V savings): An Eve sling, a Jool Sling, or an old-school bielliptic sundive (arbitrarily high apastron, followed by burning to lower you periastron). Circularization ÃŽâ€V (at 500 km altitude) would be somewhat under 27.7 km/s, depending on your apastron. Transfer ÃŽâ€V would be ~1 - 5 km/s from LKO, depending on method and efficiency.

What about Moho? Is the change in inclination big enough to make it not worth it?

You could probably aerobrake (corona-brake?) in Kerbol's "atmosphere"

O.o I didn't know Kerbol had an atmosphere . . .

Edited August 28, 2013 by chaos_forge

[Rhomphaia]

I really not understand... orbital techniques? There are none. (for sending a satellite to High Kerbin Orbit 500km, circular orbit.)

and 100 DeltaV is already extreme/

Kerbol not Kerbin. Meaning the Sun

[Sirine]

Kerbol not Kerbin. Meaning the Sun

I see now....Kerbol....the Sun...ok. Thanks...I really missing that "OL".

Now everything is clear...

[maccollo]

I think you could save quite a bit of delta V with this approach.

Go to Eve. It's gravity is higher than that of Kirbin, so the orberth effect is more significant. Encounter is so that you can do an unpowered gravity assist to swing yourself down to the orbit of Moho, then raise you apoapsis slightly so so it's a bit higher than Eve's orbit. This will allow you to pass in front of Eve the second time you encounter it. This time do a powered gravity assist pass to push your periapsis all the way down to your target altitude. Now just lower your Kerbol apoapsis.

Don't bother with Moho. At the speeds you'll be traveling at Moho's gravity will be far to weak to have any significant impact on your orbit.

Edited August 28, 2013 by maccollo

[M5000]

Do it the old fashioned way.

Launch out of Kerbin's SOI with your little satellite with an ion engine/plenty of Xenon.

Wait a bit.

Start de-orbiting yourself into the sun with the ion engine, or other preferred method of orbital transit. Burn only at or near your apoapsis only until your periapsis reaches the altitude you want. Then burn only at or near your periapsis.

Really there is no "good" way that's worth doing, aside from using Eve for an assist. But it'd honestly just be quicker to just de-orbit with ion engines. Mechjeb would help. You can have it set up a maneuver to lower your PE to some altitude (you're going to have to use multiple passes) and just let it run on in the background while you do something else.

[UmbralRaptor]

What about Moho? Is the change in inclination big enough to make it not worth it?

In principle, the change in inclination can be avoided (off-plane intercepts), but would be much more finicky, you'd need more initial ÃŽâ€V, and you'd likely get a less useful sling.

O.o I didn't know Kerbol had an atmosphere . . .

It doesn't that I'm aware of.

[DChurchill]

Do it the old fashioned way.

Launch out of Kerbin's SOI with your little satellite with an ion engine/plenty of Xenon.

Wait a bit.

Start de-orbiting yourself into the sun with the ion engine, or other preferred method of orbital transit. Burn only at or near your apoapsis only until your periapsis reaches the altitude you want. Then burn only at or near your periapsis.

Really there is no "good" way that's worth doing, aside from using Eve for an assist. But it'd honestly just be quicker to just de-orbit with ion engines. Mechjeb would help. You can have it set up a maneuver to lower your PE to some altitude (you're going to have to use multiple passes) and just let it run on in the background while you do something else.

Yeah I have a solar orbiter that started with 13km/s dV just in the orbiter with Xenon. Trying to plot slingshots would make my head hurt too much. My answer is a ****-ton of dV and do a multi-hour burn with MJ. 500km is pretty damn low, wouldn't heat be a problem?

Edited August 28, 2013 by DChurchill

[chaos_forge]

I think I'll try for the double Eve gravity assist that maccollo described (yes maybe it's slower but rule of cool)

Heat isn't a problem as far as I'm aware (last time I crashed something into the sun was 0.19 I think)

Thanks for the help, guys (or girls)!