which direction to burn in powered gravity assist?

[deepspacecreeper]

hello, i would like to ask in which direction should i burn to make use of a gravity assist? (powered gravity assist)

1. passing by the right side of a planet and i want to accelerate

2. passing by the left side of a planet and i want to deccelerate

[Superfluous J]

You shouldn't just be burning. To do this sort of stuff you're far better off making maneuver nodes. That way, you can play with it. Drag the prograde/retrograde markers around and see what your resultant orbit does. Drag the node back and forth and see what happens when it's earlier or later. Once you get what you want, just aim where the maneuver node tells you and burn when it tells you.

[Boonestorm]

What Horseman said.

Apart from that:

Left and right are highly misleading here because they depend on where you are coming from.

Pass behind a planet on its orbit to accelerate, and in front of it to decelerate. Lower periapsis=more effect (except there is an atmosphere )

I'm quite sure that burning at periapsis will give you the greatest return for your delta v (as always, because of the Orbeth effect). However, as you can not apply all the thrust at one single moment, I suggest timing your burn in such a way that you burn equally before and after periapsis.

The direction of the burn would be prograde for acceleration, and retrograde for deceleration.

Good luck!

Boonestorm.

Edited October 24, 2013 by Boonestorm