Best (bestest than mine at least) way to reach Duna?

[Guest Aaack]

So I made a small probe to send to Duna, my first mission to another planet and I'm all excited and stuff but I realize I'm terrible at chasing another planet!

As I knew I would suck at my fist attempt the probe I'm sending has ion engines, double tanks of xenon also, so thrust although minimal is not an issue.

The probe:

Right now I'm chasing the planet as I would do with a station, aligning my orbit and then go faster to catch it.

The current state of affairs:

Of course I'm taking like years for this. I'm absolutely sure there's a better way.

Do you mind share your knowledge?

Thanks!

Edited July 27, 2013 by Aaack
Cuz Imageshack's a bish and doesn't lurvs meh

[painking]

It doesn't seem like Duna was in phase when you did your ejection burn. If it was then those wittle baby xenon engines took too long with the thrust. The way you wanna do it is to wait for the planet to reach the proper phase angle, so your ejection burn will just sling you right out there and you'll run into the planet's SoI along the way.You -could- do it the rendesvous way but that's a looot of work and dV to waste. I feel, it would be better to use a nuclear engine to do all the big boy burns and have the xenon engines do smaller burns to fix your orbit how you want it to be.

[metaphor]

Since you're already in a Sun orbit:

Click on Duna and set it as your target. Then you will see a closest approach marker and two ascending/descending node markers. First look at the nodes, if it says more than 0.0 degrees burn at the next node, if it's the descending node burn north (on the navball where the "N" line crosses the horizon), or if it's the ascending node burn south (on the navball where the 180 line crosses the horizon), until it says 0.0 or NaN degrees. Then, make a maneuver node on your orbit right after it says closest approach. Tweak the maneuver node either prograde or retrograde (the green markers) until the "closest approach" marker and the "target position at closest approach" marker line up and you should get an encounter. When you get to the node burn towards the blue marker on the navball, and you should have your Duna encounter one orbit later.

So basically the same maneuvers you would do to intercept a target in Kerbin orbit, except you're in Sun orbit.

If you want to stop when you get to Duna, try to get your Duna periapsis as low as it will go by tweaking the maneuver node. When you get to Duna periapsis burn retrograde until you're in orbit.

There are more efficient ways to get to Duna (using Hohmann transfer) but with an ion engine it doesn't matter as much.

[Guest Aaack]

Metaphor, Painking, thanks guys, Im now in a perfectly circular orbit around Duna.

I've learned that with the ion engines all you have to do is start to burn before the marker reaches zero, half burn before, half after, due the slowness of speed change.

So every big manner takes about 10 minutes, I start to burn 5 minutes beforehand and that makes it predictable (alas SLOWWWW).

So, What is the Hohmann transfer and when is the best window to launch something to duna?

[painking]

A hohmann transfer is a big science word for a transfer between 2 planets on the same plane.

http://ksp.olex.biz/ http://alexmoon.github.io/ksp/

You can use that to help you with transfers to anywhere. The first link simply provides the phase angles and ejection angles needed for the transfer, the second link is more detailed.

Note that the phase angle and ejection angles aren't listed in game, so you'll have to eyeball it if you don't have any of the many flight info read out mods.

[UbioZur]

Hohmann transfer is the way to calculate the most fuel efficient way to transfer between two celestial body.

It would consist on a ejection burn from the departure body (here Kerbin) at the right time to encounter the target body (here duna), mid way you can ajust your trajectory with one or two more burn (mainly for inclination and getting the encounter at the altitude you want.

As well as painking links, here are a few more I like:

- http://alexmoon.github.io/ksp/

- http://i.imgur.com/dXT6r7s.png (nice map to see everything at once.

and there won't be any answer without a link a tutorial from scott manley right?

Edit: I like your probe design

[Guest Aaack]

Painking, UbioZur, thank you guys for reduce my ignorance!

And UbioZur, it's trivially simple but if you wish I can leave the .craft file of the lifter + probe for you somewhere.

[dave4002000]

If you want to be a little more scientific and don't want to 'eyeball' the phase and ejection angles, take a look at the Protractor mod (not sure if it's been updated to .21 yet, though) It's just a little utility that will show you transfer windows, ejection angles and dV requirements for the burn, and a bunch of other stuff for all bodies in the Kerbol system.

::edit:: It has been updated, you can find it here http://forum.kerbalspaceprogram.com/showthread.php/21544-21-Protractor-Rendezvous-Plugin-v-2-4-2

Edited July 27, 2013 by dave4002000

[UbioZur]

Painking, UbioZur, thank you guys for reduce my ignorance!

And UbioZur, it's trivially simple but if you wish I can leave the .craft file of the lifter + probe for you somewhere.

Thanks, I can see how you have done it. I won't need a .craft file.