Gravitational Slingshots

[simplemunrockets]

How hard would it be to calculate planetary slingshot trajectories in KSP? And, more importantly, how long would the transfer windows be? I've just thought of this a few minutes ago, and it would be really cool if we could pull this off. I know people have already done this, but they've all done massive corrections after the flyby.

Edited April 27, 2013 by simplemunrockets

[Cdr_Zeta]

Howdi,

I kinda didnt think this was available...then I tried a direct shot to Eve, or some other body, and had major problems; I couldnt even get out of Mun gravity; it was interfering.

I will tell you that in most cases, to get the best flight..time; time needs to be on your side and added into the equations; by the looks of things it may take months to get out there (!); efficiently that is!

I am tending to give up on the math...the manuver nodes are working quite nicely for me now...

But I agree that calculations seem abit off; sometimes there is no choice and alot of efficiency is lost making for a one way trip.

Set an outside focus to get max time warp; and watch the rotations of the bodies and plan accordingly; I will be doing this to study the 'sim-game'; I then plan each trajectory accordingly; Mun to Minmus seems to be my best bet; and there arent too many good conjunctions (for escape); maybe plan an escape depending on their positions and pick the planet that way; that gets you out sooner.

Cdr Zeta

[Nobody_1707]

Yesterday, my Münar rescue probe ran out electricity during a Münar encounter then slingshotted around into a second Münar encounter where it crashed a good click away from Sidson, whom I was supposed to be rescuing. I didn't realize that you could us a Münar slingshot to create a Münar landing trajectory. It would have been a cool way to land if I had control over the ship.

[simplemunrockets]

I'm talking about having an intentional slingshot from planet to planet, like this: http://upload.wikimedia.org/wikipedia/commons/5/5c/Tour-v1-2.svg

Also, I think I've found an optimal Kerbin-Duna-Jool trajectory. You transfer to Duna when Duna is at 44.36 degrees to Kerbin and Jool is 107.2 degrees to Kerbin, make sure the predicted apoapsis after the encounter is at Jool's orbit, plan corrections, and slingshot. Calculating the window time is beyond me though, so I'll just leave this here.

[Giggleplex777]

I've done many slingshots before. Just use the maneuver nodes to help you. Minor changes to your orbit can get you to places without having to get the window right.

[Istas]

I too would be interested in this.

[magnemoe]

Slingshots work well in KSP, however they are pretty hard to plan as you need multiple planets to align. Jools moons is an interesting place to do them as the moons are near each other, I have used Tylo to get to Laythe from Pol very cheap. Used an combination of letting it bend my path with an small burn deep inside it gravity well to send me straight for Laythe.

[AustralianFries]

Do slingshots work? Yes.

Can you consistently plan them? Usually not.

When you get everything in the right place and all aligned, slingshots are a very cost efficient way of getting to places. However, it's usually not something you can plan to do. It kind of just has to happen at the right moment. I've used the Mun as a slingshot to escape Kerbin's SOI and have gotten to Minimus way more efficiently.

[M5000]

Do slingshots work? Yes.

Can you consistently plan them? Usually not.

When you get everything in the right place and all aligned, slingshots are a very cost efficient way of getting to places. However, it's usually not something you can plan to do. It kind of just has to happen at the right moment. I've used the Mun as a slingshot to escape Kerbin's SOI and have gotten to Minimus way more efficiently.

How do you get to Minmus if you're not in Kerbin's SOI?

[loppnessmonsta]

It would be nice if there were a way for the less mathmatically and astrogationally inclined to plan this sort of thing out. The way I'd set it up is to have a visual indication of where each planet's transfer window opens and closes (Select target planet through a menu). Then have that interface disabled... until you have, say, a Telescope or two in orbit. As long as they're active you can continue to use the more detailed interface, but if something happens to them (run out of juice, Jebediah takes an interest, etc) that interface goes away until you replace them.

[ROFLCopter64bit]

Instructions:

Math:

New velocity = 2P + Old Velocity

(but if you do it the other way round, the wrong way)

New velocity = Old Velocity - 2P

[AustralianFries]

How do you get to Minmus if you're not in Kerbin's SOI?

I was referring to two different instances. I guess I didn't word that so well. I meant: I've used the Mun as a slingshot to escape Kerbin's SOI, and have also used it to get to Minimus in a more efficient manner.

[ThatBum]

In order to use a slingshot and go where you expect to go instead of...somewhere, it takes a lot of planning ahead. Not to mention waiting a long time for the planets to align. The type of alignment that allowed the Voyager missions to happen happens once in 175 years. I'd would be a similarly massive undertaking to get an entirely gravity powered Kerbol system grand tour.

See Wikipedia's thorough article on it.

[Hasegawa]

Instructions:

http://i.imgur.com/8x81Ape.png

Math:

http://i.imgur.com/sx1szkB.png

New velocity = 2P + Old Velocity

(but if you do it the other way round, the wrong way)

New velocity = Old Velocity - 2P

If you wanted to reduce your orbital speed (to, for example, go to Moho) wouldn't the direction you claim to be the wrong way actually be the right way?