Jump to content

Would this be enough Delta V?


Recommended Posts

I can't seem to read any of the dV maps out there, since it either seems to say that you only need about 180 m/s to get from Kerbin to Jool, or 40,000 m/s to get from Kerbin to Jool, and I know those are both wrong.

Anywho, I am building a craft that is designed to go from LKO to Jool, and then (depending on how the orbits line up) from a Jool orbit to a low Vall orbit, low Pol orbit, and low Bop orbit. Then once that is all done, I will burn from whichever of the three bodies I am orbiting to get back to Kerbin.

My craft has 8568.9 m/s dV to pull this off (although it will have a bit less once I add the atmospheric probe for Jool).

Is that enough fuel, and by how much is or isn't it enough?

Edited by Themohawkninja
Link to comment
Share on other sites

To read a delta-v map, you simply add up all the numbers on the path you plan to go on. I use this one, very accurate if you fly right: http://i.imgur.com/UUU8yCk.png

Also, is that 8568 delta-v in orbit or on launchpad?

It's from LKO.

Also, that would explain why I thought it was saying that it only took 370 m/s to get to Jool. I didn't know you had to add all the beforehand values together.

Link to comment
Share on other sites

Yeah, about 2.3km/s to get to Jool. If you aerocapture you can save a bunch of delta-V on braking and I'd suggest that because you're looking at another 2.5km/s. You'll need somewhere on the order of 3km/s to get back to Kerbin but aerocapture once again saves you delta-V (somewhere in the neighborhood of 2km/s, probably more). So roughly 10km/s round trip without aerocapture, somewhere between 6~8km/s with aerocapture (that includes corrections and safety margin). You should be fine.

Also, it's worth noting that most of the delta-V maps I've seen are hugely optimistic. Nowadays I only use them for lander planning.

Link to comment
Share on other sites

Anywho, I am building a craft that is designed to go from LKO to Jool, and then (depending on how the orbits line up) from a Jool orbit to a low Vall orbit, low Pol orbit, and low Bop orbit. Then once that is all done, I will burn from whichever of the three bodies I am orbiting to get back to Kerbin.

Going into low Jool orbit at the start and leaving from a moon (except maybe Tylo or Laythe) at the end is wasteful on dV. It's generally much cheaper to start with the moons and then dip down to Jool for the shot back to Kerbin.

Use the aforementioned map: http://i.imgur.com/IV8rzue.png along with the threads by its creator to get a handle on its intricacies: http://forum.kerbalspaceprogram.com/threads/41652-A-more-accurate-delta-v-map and http://www.reddit.com/r/KerbalSpaceProgram/comments/1iw30a/a_more_accurate_deltav_map/

And http://alexmoon.github.io/ksp/ to find good launch and return windows.

And for giggles, here's the solar system: http://i.imgur.com/WGOy3qT.png

Link to comment
Share on other sites

This map got me thinking: are there LaGrange points in KSP?

You can fake L3, L4, and L5 since they are on the orbit, but L1 and L2 are not doable. There's a reason for why this is in KSP but it's escaping me at the moment. I'll let someone smarter show up and answer. :confused:

Link to comment
Share on other sites

You can fake L3, L4, and L5 since they are on the orbit, but L1 and L2 are not doable. There's a reason for why this is in KSP but it's escaping me at the moment. I'll let someone smarter show up and answer. :confused:

The reason is for a Lagrange point you need an uneven SOI, and unfortunately all the SOIs in KSP are perfectly circular.

Link to comment
Share on other sites

The reason is for a Lagrange point you need an uneven SOI, and unfortunately all the SOIs in KSP are perfectly circular.

It's because you need three bodies, but KSP only does two-body physics. KSP only does two-body physics because you can analytically solve it, whereas you can't in general solve 3-body problems analytically (which would mean you couldn't time-warp as much as we like to do).

Link to comment
Share on other sites

This thread is quite old. Please consider starting a new thread rather than reviving this one.

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...