Taking off from Duna

[box_brain]

Hi everyone, my first thread! I would like to know efficient ways to take off from Duna consuming the least amount of fuel possible. Also would like to know how to dock my refueling module to my Duna lander which is in Duna orbit of about 150,000m. thx!

[ComradeGoat]

Takeoff from Duna more or less mirrors takeoff from Kerbin. Go straight up for a short distance (say, 4,000 metres), then do a gravity turn east to the 45 degree mark, then turn progressively more and more horizontal until you get an orbit.

On a body without atmosphere, as long as you have sufficient TWR to keep your apoapsis in front of you, you can turn due east immediately on takeoff (and being sure you won't hit any mountains), but maybe gain a few hundred metres first, just to be safe.

The docking is much the same as it is in Kerbin orbit, only the orbit is tighter so your relative heading will wander a bit small. Probably best practice docking in Kerbin orbit to get the hang of it.

Good luck!

[rodion_herrera]

It really pays to do the gravity turn early when taking off from Duna, because you will be maximizing your horizontal velocity early in the ascent, which is good because it means you will reach your apoapsis faster (and circularize quicker) since you can orbit Duna at a much lower altitude (say 55 km). You can imagine your Duna ascent profile as roughly half that of a Kerbin ascent profile, and you get to your final velocity for orbiting Duna faster, and so you save on propellant. Put the two terminal velocity tables of Kerbin and Duna side by side and you can see clearly how you can take advantage of Duna's thin atmosphere to get you to orbit quickly. Once you get to your 55km circular orbit, you can then setup transfer to a higher orbit where your refueller or station is located.

[GreenDragon]

Also make sure to use the nucs, the atmosphere is so thin that they are by far the best engines for this.

[AmpsterMan]

And remember, you don't usually need much TWR to get off of Duna. I've done the ascent with a Poodle, or a few 24-77's

[box_brain]

Thank you very much for all the info! I managed to get my lander off of Duna and I still had enough fuel to get back to Kerbin! However, my 1st Duna Lander is still stranded in orbit. I got the orbit equilateral with 2 units of fuel left. Every refueling module I've sent gets into a highly irregular orbit. Any easy ways to adjust my orbit to get it equilateral?.

[hubbazoot]

Thank you very much for all the info! I managed to get my lander off of Duna and I still had enough fuel to get back to Kerbin! However, my 1st Duna Lander is still stranded in orbit. I got the orbit equilateral with 2 units of fuel left. Every refueling module I've sent gets into a highly irregular orbit. Any easy ways to adjust my orbit to get it equilateral?.

To circularize your orbit, you can burn radially inward or outward to cancel off your vertical velocity, and then burn prograde or retrograde to make sure you're going fast enough to round out. Since you're trying to rendezvous, I suggest very slowly changing its orbit to match your target. Match planes, match Ap/Pe, then do a rendezvous.

[box_brain]

Alright hubbazoot, I'm sending my third refueling module over to Duna, Ill tell you how it goes....

[box_brain]

ok, I finally docked my refueling module to the lander! I took a screen shot but i dont know how to post screenshots....

[Scarecrow88]

Interesting read. I have finally landed on Duna with enough fuel to potentially get home again, so will see how it goes.

[hubbazoot]

Another thing that will save fuel is to have your lander ONLY land. Transport it there, leave your planetary stage in orbit, land, rendezvous, leave your lander at duna, travel home.