Requesting some math help... I think..

[jordsta95]

Hey guys, so I have never really been one for working out Delta V and how much ISP engines give, etc.

But I have never sent a crew to other planets before, so it has never bothered me... until now :/

So here's what I'm going to be doing, sending a craft (which is currently at a parking orbit of 170k around Kerbin) to Dres and back.

Sounds simple. But I don't know how much delta v I will need to get to Dres, from my orbit, and then make an orbit at around 200k (or so) then return back to Kerbin (assuming all maneuvers are almost perfect; about 10 minutes off either way).

So I am wondering if there is a calculator for this, as the only thing I found online was a launch to Dres calculator and when to launch etc.

Thanks for the help...

I really am a noob. I usually just add a bazillion boosters, and if that doesn't work then I give up. But I am determined... and Jeb and Bill really want to go to Dres

[Ralathon]

Just fill in the original orbit, the target orbit here and it'll tell you how much dV you need and what the phase angles have to be.

Be sure to have some reserve dV though. Dres has a bit of a wonky orbit, so you'll need a bit of dV to account for that.

To get back you need the exact same dV values, just in reverse. So for a Dres return mission you're looking at about 4km/s of dV if you start in LKO.

[Pecan]

Search for a deltaV map and/or the many discussions about them on these forums. The maps will tell you how much deltaV you need for each step of a mission to/from any planet or moon including landing and taking-off again (where possible).

[DeMatt]

I would recommend installing and using Kerbal Engineer Redux once you've determined how much delta-V you need on your rocket, and are trying to build it. The onboard delta-V calculator saves SO much effort over simply strapping MOAR BOOSTERS on, you'll never want to construct without it again.

[Tank Buddy]

If you've never gone interplanetary before, I'd highly recommend you go to Duna First. The atmosphere helps reduce DV requirements by a ton.

For mission planning use these:

http://ksp.olex.biz/

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

Here's a DV Chart:

Also, here is a video that will show you a transfer to Duna:

[capi3101]

Here's another delta-V map; this one's got inclination change values, so I'd recommend using it over the older chart Tank Buddy has posted above.

.

So to read it...

4500 to Low orbit

680 out to stationary orbit

180 out to Mun orbit

70 to minmus orbit

20 to escape Kerbin

130 to Duna transfer

480 to the Dres transfer

1010 for the inclination change

1140 to get captured by Dres

150 to get to Dres low orbit

430 to land

430 to launch

150 to escape Dres

1140 to transfer back to Kerbin

1010 for the inclination change

and the rest is free

Total Delta-V for the entire mission: 11,250 m/s

That's assuming optimal conditions - you could tack on more for a higher margin of error if you so choose. Since 7020 of that figure is for the flying there and back bit, I'd plan for that part to have anywhere from 8775 to as much as 10,530 m/s of delta-V, especially if you haven't got a lot of experience doing interplanetary transfers.

Edited February 7, 2014 by capi3101

[Jimbimbibble]

The above posts will give you a good idea how much dV you need, but I have some advice that will help you fly more efficiently. The most efficient way to go interplanetary is to burn when you are as close as possible to the planet. Whether you're trying to go for escape or capture, get your Pe as close as possible without crashing or going in the atmosphere (unless you're doing an aerocapture of course). Also, do the whole burn at once. It's inefficient to burn for escape and then again to raise your sun Ap for the encounter. Mechjeb does a good job at transfers, so I'd suggest using it until you get the hang of it.

[Taki117]

The above posts will give you a good idea how much dV you need, but I have some advice that will help you fly more efficiently. The most efficient way to go interplanetary is to burn when you are as close as possible to the planet. Whether you're trying to go for escape or capture, get your Pe as close as possible without crashing or going in the atmosphere (unless you're doing an aerocapture of course). Also, do the whole burn at once. It's inefficient to burn for escape and then again to raise your sun Ap for the encounter. Mechjeb does a good job at transfers, so I'd suggest using it until you get the hang of it.

With this though, if your initial burn time is very long (more than about 5 minutes) you should break it up into two burns over two orbits. i.e for a 10min burn burn 5 min on the first orbit (2.5min on either side of the maneuver node) and then finish the burn on the second orbit.

[thereaverofdarkness]

Someone once said that once you get to Earth orbit, you're halfway to anywhere. This holds true in KSP as well. ~4500 dV will get you to orbit, about ~9000 dV will get you anywhere. I find I need around 2500 dV to perform a standard Hohmann transfer to Eve, Duna, or Jool, and mabe 1500 to stabilize once I get there. Those are very approximate figures, but I've not yet had a fuel problem with 4500 dV after orbit, unless I needed fuel to land. Easy solution: factor the lander as payload mass and don't calculate its dV for craft range.