Delta-V map

[Nuprin Feelgood]

I had a copy of this on my desk which met with an unfortunate coffee spill.

I went to print a new one, but the original forum post where I had found it was lost in the recent kerfuffle.

I did manage to find a copy of it online, and so I thought I would repost it for those who use it.

I apologize for not knowing or remembering the original author of the image.

I find it to be very useful and easy to read, so thank you to whomever created it.

I repost it for others with respect.

There is also an excellent map found in this thread: http://forum.kerbalspaceprogram.com/showthread.php/20993-Request-Delta-V-maps?highlight=delta

[Scottiths]

I have this saved to my desktop. I find it more useful than the other maps. Not 100% accurate, but if you have the fuel to make it by this map you will have a little extra wiggle room left over. (IE: I can usually get kerbin orbit with 4300 m/s which gives me an extra 200m/s according to this map)

[Phoenix Aerospace]

Forgive me for sounding like a N00B, but how exactly does one use this map? Thanks in advance.

[flightmaster]

Forgive me for sounding like a N00B, but how exactly does one use this map? Thanks in advance.

N.B. I'm going to make the assumption you understand Delta V, if not, let us know.

This map is used to plan your trip to other planets. We'll start small.

If you look at the number in the middle of Kerbin, you'll see that it says 4500. This 4500 means that you'll need 4500 m/s Delta V (change in velocity) to get into orbit around Kerbin. From there, you need 860 m/s Delta V to intercept the Mun and you'll need a further 210 m/s Delta V to turn your intercept into an orbit (otherwise you'll just fling off the other side).

To get to Gilly, for example, you'll need 4500 m/s to get into orbit, 950 m/s to escape Kerbin's SOI and intercept Kerbol (the Sun), 80 m/s to intercept Eve, (depending how you do the next part) 1310 m/s to orbit Eve and then 1650 m/s to intercept Gilly. Another 210 m/s to get into orbit and 35 m/s if you want to land. So all up, if you do it exactly as it says on table (there are other, more efficient ways), you'll need a ship capable of having 8735 m/s Delta V in order to land on Gilly.

I hope this makes sense!

[CalculusWarrior]

Pretty cool map! How do you calculate the d-v required to take off from a planet? I have all these great resources telling me how to get there, but I usually take off by the seat of my pants and hope I have enough to get into orbit.

[flightmaster]

Pretty cool map! How do you calculate the d-v required to take off from a planet? I have all these great resources telling me how to get there, but I usually take off by the seat of my pants and hope I have enough to get into orbit.

Not sure, the number for Kerbin (4500) indicates how much it requires to take-off but that might just be in the wrong place, the author may have meant to put it as the "orbit" number.

[nats]

Pretty cool map! How do you calculate the d-v required to take off from a planet? I have all these great resources telling me how to get there, but I usually take off by the seat of my pants and hope I have enough to get into orbit.

I usually assume the same to take off and orbit is the same required to land - so 640m/s to take off and get back into a stable orbit around the Mun. But I also assume around 1000m/s is required to get back into a stable orbit around Kerbin that isnt shown on the map (unless you aerobrake in which case returning to Kerbins ground is free). Also adding a 1000m/s like this gives me my margin for error because just going by the numbers on this map I was running out of fuel on the Mun and not able to take off again.

So to return from anywhere, as well as get there, you add all the numbers to get there plus all the numbers again to get back (except the 4500m/s launch from Kerbin) and add an extra 1000m/s for safety.

So as examples: it will take 7800m/s for a round trip to Minmus, 8300m/s for the Mun and 9800m/s for Duna. These arent quite right because any planet with a decent atmosphere is practically free for landing on it if using parachutes and also aerobraking can greatly slow down you for an orbiting maneuver, but it gets it roughly right. At worst you might have a little bit of fuel left when you get back to Kerbin.

Edited April 22, 2013 by nats

[tavert]

I think the Dres transfer number on this is overly optimistic. The inclination and eccentricity of Dres make things a little trickier, but I've seen closer to 1500-1600 m/s on the ejection burn rather than the 1300 m/s that this map seems to suggest. I wonder whether the original author got these from simple calculations or in-game experiments...

[Matrix Aran]

I think the Dres transfer number on this is overly optimistic. The inclination and eccentricity of Dres make things a little trickier, but I've seen closer to 1500-1600 m/s on the ejection burn rather than the 1300 m/s that this map seems to suggest. I wonder whether the original author got these from simple calculations or in-game experiments...

Same with the Moho transfer, pretty optimistic considering the plane change.

[Tristavius]

I've been using this chart for a while now, but I've found one small flaw - the delta-v for a return journey both in practice and from sources such as the wiki doesn't seem to correlate to any numbers on this chart. For example, people report 1500-2000m/s to launch from and make Duna orbit (I'm guessing this is the 1380m/s + the 370 orbit m/s) but then the return burn to kerbin seems more like 620m/s. Am i reading something wrong, or is it just the case that this is a 'from Kerbin' kind of deal only... and if so has someone made maps focused around delta-v from other bodies?

[Tommygun]

These charts are good for casual reference, but I wish someone would update them and make up a return Delta V map as well.

[Tristavius]

Hmmm, I'd be happy to do a series of them or make something web based if I could get the values from somewhere...

[Tommygun]

I'd offer to help, but I have the math skills of a gerbil.

[Krizzen]

I'd love to photoshop up a Delta-V map, but I'm not sure how to determine the values without actually flying to each body. If anyone would be willing to provide the Delta-Vs, I'll make a nice intuitive map!

[tavert]

Perhaps we could look into a collaborative spreadsheet or Desmos notebook or something to work out the numbers. Something interactive would be ideal so you can play around with departure and capture orbit altitudes, etc.

[RoboRay]

Return cost is nominally the same as the outbound cost. The differences you are seeing are likely due to eccentricity, as the planets have moved considerably.

Aerobraking differences can also result in significant deviations.

Edited May 19, 2013 by RoboRay

[Tristavius]

Return cost is nominally the same as the outbound cost. The differences you are seeing are likely due to eccentricity, as the planets have moved considerably.

I may be totally wrong here, so apologies I am, but I really don't think that's the case?

For example, it costs approx 1060m/s to get from LKO to a Duna intercept. Out of that, 950 m/s is the burn to leave Kerbin SOI, and a relatively small amount (110m/s) to push the apoapsis out to Duna. On the way back I can envisage the same 110 m/s being required to get from a Duna exit to a Kerbin intercept, but the burn to leave Duna SOI has got to be a lot lower than the 950m/s on Kerbin as Duna has a much smaller mass.

Possibly totally wrong every time I think I have my head around this game someone shows me otherwise!

[tomf]

The delta v charts are reversible, except for landing and taking off on planets/moons with atmospheres.

If it takes 950 to leave LKO, 100 to transfer to Duna and 600 at Duna to circularize then to get home from Duna is going to require 600 to leave Duna, 100 to transfer to Kerbin and 950 to circularize at Kerbin. (all these numbers assume a perfect Hohmann transfer and ignore the eccentricity and inclination).

Of course you can aerobrake when you arrive at a planet so that delta-v is nearly free and getting back from Duna ends up costing less than getting there.

[Tommygun]

When you are coming back from a moon to its parent body, that is from the Mun to Kerbin, shouldn't it take less delta V as you are going back down into the "gravity well" instead of climbing out of it.

[Akalaël]

Yesterday, I was in an encounter with Moho. I know that, if you arrive at it's periapsis or apoapsis it makes all the difference.

The map indicates 2200 m/s.

I needed 5000 m/s...

[kurja]

When you are coming back from a moon to its parent body, that is from the Mun to Kerbin, shouldn't it take less delta V as you are going back down into the "gravity well" instead of climbing out of it.

No, if you're transferring from Mün orbit to Kerbin orbit because you'll need every bit as much delta v to circularize around Kerbin as it cost you earlier to leave Kerbin orbit. You'll need less delta v only if you either aerobrake or go down like a missile without intent to orbit, you see, these values are for transferring from orbit of one body to orbit of another body.

[tomf]

Yeah Moho can be pretty evil because it goes around Kerbol so fast and has little gravity of its own.

If you are just a few degrees off parallel to its orbit when you arrive, extremely likely due to it's inclination and eccentricity, then circularizing can cost several thousand more than you expected.

[Tristavius]

The delta v charts are reversible, except for landing and taking off on planets/moons with atmospheres.

If it takes 950 to leave LKO, 100 to transfer to Duna and 600 at Duna to circularize then to get home from Duna is going to require 600 to leave Duna, 100 to transfer to Kerbin and 950 to circularize at Kerbin. (all these numbers assume a perfect Hohmann transfer and ignore the eccentricity and inclination).

Of course you can aerobrake when you arrive at a planet so that delta-v is nearly free and getting back from Duna ends up costing less than getting there.

That makes sense I guess the problem with all these charts is they show kerbin differently to other planets. Shouldn't it actually show 950 as the 'Orbit' value for Kerbin (and the Land value as 4500 - 950)? Not sure how you'd show the intercept values then mind you... I guess they'd have to go planet to planet rather than via the Sun

[Specialist290]

That makes sense I guess the problem with all these charts is they show kerbin differently to other planets. Shouldn't it actually show 950 as the 'Orbit' value for Kerbin (and the Land value as 4500 - 950)? Not sure how you'd show the intercept values then mind you... I guess they'd have to go planet to planet rather than via the Sun

It does, sort of, in that the value going from Kerbin (and the other planets) to the sun is the value for crossing escape velocity in either direction. Going out from the planet, you're trying to go over its escape velocity; going in towards the planet, you're trying to slow yourself down so it captures you. The Landing values work for both takeoff and landing (since a soft landing is, ideally, basically the exact reverse of a takeoff; all bets are off if you decide to use the "lithobreaking" technique, though, and atmosphere will help you out if you go for aerobrake / aerocapture -- although if you land and take off again, you'll have to fight a bit against that very same atmosphere).

Edited May 20, 2013 by Specialist290

[astocky]

I found another map that is very similar (but a little easier to understand here) - remember though they are all estimates with some deal of conservatism built in:

http://www.skyrender.net/lp/ksp/system_map.png

It for example shows to get to Duna you need:

Take-off from Kerbin (4500)

Escape Kerbin SOI into Kerbol Orbit (950)

Capture into Duna SOI (110)

Establish Stable Duna Orbit (370) - you can aerobrake to reduce this substantially

and Return

Eject from Duna Orbit (370)

Establish Correct Kerbol orbit (110)

Capture into Kerbin SOI (and capture orbit) (950) - still only 1 number, and you can aerobrake to reduce this substantially.