Slingshot maneuver

[Hello moto]

If I am orbiting at the very edge of Kerbin SOI, would it be cheaper in fuel to transfer straight from there to where ever else or would it be cheaper in the long run to slow my speed so I slingshot around the planet and gain speed in the process?

[Ralathon]

Depends a bit on where you're going. But in general it'll be better to slingshot around the planet due to the Oberth Effect. Rocket motors are more efficient when moving fast in the direction of thrust.

[SpaceSphereOfDeath]

I'm sure it would be MUCH better to burn for escape near the planet, if your going to the moons of kerbin however, I'm not to sure, why it's better to escape near the planet, just look up the oberth effect on youtube or Teh interwebz

EDIT:my first ninja

[Hello moto]

Ok thanks, I'm setting up a secondary refuelling station near Minmus orbit for the interplanetary transfers and this will help a lot.

[Kasuha]

Edit: Nevermind...

Edited September 15, 2013 by Kasuha

[Scotius]

It's useful, but usually too much hassle. And why would you burn significant portion of the fuel to get near Minmus orbit, so you could do a Kerbin slingshot? I never bother, unless Mun kindly agrees to give my ships that extra kick when they go interplanetary.

[SRV Ron]

If I am orbiting at the very edge of Kerbin SOI, would it be cheaper in fuel to transfer straight from there to where ever else or would it be cheaper in the long run to slow my speed so I slingshot around the planet and gain speed in the process?

In your case, far cheaper to transfer straight to escape velocity.

What does saves tons of delta V is taking advantage of the slingshot to slow down, speed up, or make major changes in orbital plane as this maneuver demonstrates;

It is even possible to get a near capture into orbit under the right intercept;

Slingshots to an aerobraking landing on Kerban in one maneuver are the results of taking advantage where you do the escape burn from Mun;

The same will work for an escape from Kerban directly to Jool, but takes precise timing to get that transfer window from Kerban without having to go into solar orbit first. Such maneuver planning will require orbital tables and precise dates and time.