How much delta-V for a round trip to Duna?

[CaelumEtAstra]

I'm doing a Constellation style Duna mission but i'm not quite sure on the amount of delta-v required to go from Kerbin to Duna and back to Kerbin.

The Wiki says with aerobraking it should take about 1,700 m/s to get to Duna, but this transfer window planner says it's about 1,678 m/s there and 1,636 m/s back for a total of 3,314 m/s. The thing is, I'm not going to be aerobraking, but doing insertion burns and some minor orbital corrections for rendezvous and such.

In general, how much Delta-v do I need for this trip in total?

Thanks in advance.

Edited May 20, 2015 by Mrsupersonic8
Fixed grammar.

[impyre]

I was able to launch an unmanned "crew return module" that had a Duna encounter and 2300m/s of dV. It was able to establish capture around Duna, get a Kerbin return encounter, and establish Kerbin capture all without any aerobraking. Add the encounter dV (which was on the transfer stage, not on the return module) of around 1080 and it comes to a total of about 3400m/s. Probably could've done a little closer to the listed amount of 3314, but I like to play it safe. This was in 1.0.2, using only stock parts. The 2.5m poodle engine specifically. That said, that won't allow you to do any landing or orbital maneuvers (including rendezvous) once there, you'd need other craft for that purpose. For rv maneuvers, you may want an extra 500-1000m/s. You could go with less, but intercepts would be long and annoying.

I sent crew return modules, landers/exploratory vehicles, fuel/supplies, all in separate crafts/launches.

That 1700m/s estimate seems a bit low, even with aerobraking... it'd be a challenge to manage.

Edited May 20, 2015 by impyre

[Tank Buddy]

Using this Delta V map, you can add up all of the values along the path to your destination, but be sure to exclude capture burns because you can aerobrake both ways. It adds up to about 1,100 m/s to get there and just under 500 m/s to return. NOTE: you should add some Delta-V to the first value for orbital maneuvering in Duna orbit. This includes inbound aerobraking, but excludes landing on Duna. NOTE: these values start from Kerbin orbit, excluding the 3500 m/s to get to orbit). Since you are inexperienced in interplanetary travel, you should add a few hundred m/s of wiggle room in your craft design. EDIT: I can't find the Delta-V to land, but is is not too far off from the old value, it is on the forum somewhere. And one tip: make your lander somewhat aerodynamic; Duna does have an atmosphere (duh), so design accordingly.

Edited May 20, 2015 by Tank Buddy

[Jonboy]

The burn to get you to Duna will cost 1,100 m/s. Since you're not aerobraking at Duna, it will cost about 500 m/s to insert yourself into orbit once you get there. It will cost about 650 m/s to transfer back to Kerbin. If you're planning to directly enter Kerbin's atmosphere and land from there, your total Delta-V is about 2,250 m/s.

If you plan to insert yourself into Kerbin orbit manually once you get back, it will cost you 1,050 m/s to do that. Which means your round trip Delta-V is 3,300 m/s.

[CaelumEtAstra]

Thanks to all. Now to get building!

[ElectricDeath5]

Did you times the deltaV needed by 1.25 for a safe ammount or is that just the plain deltaV?

[Firemetal]

Just try 4KM of Dv to be on the safe side.

Thanks

Fire

[Plusck]

You can do a Duna surface-to-surface round trip (just) with the "Kerbal X" stock craft, with minor tweaks (removing monoprop, adding drogue chute(s)). It has about 6.3km/s total, I think, so that leaves about 4km/s from LKO. If you're not going to aerobrake, you need to add about 600m/s (I guess).

[Snark]

Just to be clear, this is quite an old thread that got revived.  It's still a reasonable topic of discussion, so if someone now has questions to answer, it's worth asking them and having them answered.  But please note that the folks who posted up to May of last year have already said their piece and probably don't need more feedback at this point. 

Here's what a typical dV budget to get to Duna looks like.

1. Get to Kerbin LKO.  I'll assume you already have a handle on this one. 
2. Eject to Duna.  http://ksp.olex.biz is a useful tool for this.  Exact amount depends on how close to the ideal window you are, and how high your LKO parking orbit, but it's on the order of 1050 m/s.
3. Arrive at Duna and aerobrake, then land with parachutes (possibly a brief burst of retro-thrust to cushion landing, since it can be hard to slow down enough with just parachutes).  Minimal dV needed.
4. Ascend from Duna surface to low Duna orbit.  This varies depending on ship design, ascent profile, TWR, height of parking orbit, etc., but a ballpark figure is around 1200 m/s.
5. Eject from Duna orbit to go home to Kerbin.  Again, http://ksp.olex.biz, this is around 600 m/s.
6. Arrive at Kerbin and aerobrake, then land with parachutes.  Minimal dV needed.

So, starting from Kerbin LKO, you'll need a bare minimum of around 3 km/s for a trip to Duna surface and back.  If you leave your return-to-Kerbin fuel in orbit around Duna when you go down to the surface and back (a not uncommon mission design), then that'll help your fuel budget.

Allowing a bit of safety margin, then 4 km/s of dV should be ample for the trip, as long as you have some reasonable launch windows.

[ElectricDeath5]

thanks!!!!!