Handy/interesting graphs/charts.

[MarcRan17]

hey all, I've been working on some charts and diagrams for KSP lately to save us the trouble of bringing up a calculator or doing math at all really.

The first chart is a phase angle diagram (fairly large image btw) which has both phase angles for leaving Kerbin (to any desirable planet) and return phase angles for making it back with optimal efficiency. To use this diagram, imagine you're in the map view looking down on the solar system. Rotate your view so that Kerbin's marker is pointing directly right like in the diagram. Then, rotating as necessary to keep Kerbin in this position, time warp until your destination planet and Kerbin make the angle shown in the diagram. If you leave your starting planet when this angle is achieved, you should have a perfect encounter with your destination planet. Note that although these angles are very specific, you can still make a successful transfer within probably a 10 degree window. Also worth noting, if you're travelling from a planet in a Higher orbit to one in a lower orbit, do your ejection burn on the daylight side of the planet so that you slow down as you leave the planet. The opposite is true if you're travelling to a higher orbit. And another important point is that this doesn't account for eccentricity of the orbits either, so the values, despite being awfully precise, are actually averages, unless the planet in question is in a perfect circular orbit.

On the bottom of the phase angle chart there is a delta-v map as well. This map will show you the delta-v required to get from one situation to another. Red numbers are delta-v required to transfer between the indicated planets. Green numbers are the delta-v required to achieve orbit around that body (ie get captured) but this can be dramatically reduced by aerobraking wherever possible. Blue numbers are once again transfer delta-v's but this time between a low planetary orbit and a moon orbit. Black numbers are the landing/getting back to orbit values. This will tell you how much you need to land on a planet and this is also the amount you'll need to reach orbit again from the ground. NOTE: that this is much, much lower on atmospheric planets as you just need enough delta-v to drop your periapsis sufficiently into the atmosphere, at which point the air will slow you down and you can use parachutes to land. However!!! the listed values ARE accurate for achieving orbit. (yes that means that Eve is very difficult to escape, and Although there has been some controversy over whether or not 12000 is correct, this is the generally accepted number.) Once again, these numbers don't account for eccentricity nor do they account inclination. This means that for planets like Dres, Eve, Moho, and especially Eeloo, it's a good Idea to budget about 1000m/s more delta-v if you can.

The second diagram is a rocket delta-v graph. Now that you know how much delta-v you need, its time to see how much your rocket has. (I lied when I said no math I guess) This calculation actually has to be done stage by stage, remembering which parts have been jettisoned at which points in the flight, etc. Start with your first stage: Add up the total fueled mass of the rocket. Now divide that by the mass of your rocket after the first stage has burned out. I call this number the Mass ratio of that stage. With all the liquid fuel tanks, except the probe-sized ones, the maximum possible Mass Ratio is 9, but you'll never quite achieve this because a fuel tank alone is useless, and requires engine. Engines, with a mass ratio of 1 (no fuel, so full mass = empty), will decrease the mass ratio of the fuel tank/rocket assembly. The probe sized tanks have a maximum mass ratio of around 5.3. Also, worth noting, is that although I have noted the ION engine's Delta-V at nine, the stock Xenon tanks actually have a MR of roughly 2.4, meaning that without some ingenuity, their maximum delta-v is around 32000m/s, which is still blasphemously high. Find this number on the x-axis of the graph. now figure out which Isp line applies to your first stage by calculating the average Isp. If you only used one kind of engine or all the first stage engines have identical Isp's, then this number is the same as the Isp for any one engine. If you have mixed engines firing simultaneously, then you must calculate the Isp of the stage like this:

total Isp = [( Isp1 * thrust1) + (Isp2 * thrust2) + ...]/thrust1 + thrust2 + ...

Isp1 is the Isp of the first kind of engine, thrust1, first engines thrust, Isp2 second kind of engine's Isp, etc.

Once you've identified which Isp line most closely resembles your rockets stage, trace that line to the point where your mass ratio sits on the x-axis. The y-value at this point is the delta-v of that stage. Once again, remember that this number is less than calculated while you're in the atmosphere and/or fighting gravity (launching basically) so it's a good Idea to over compensate by about a thousand delta-v depending on the size of your rocket.

And the last diagram is a REALLY BIG IMAGE(no joke here guys, it's like 10,000px wide and 1200-1500 tall) which is a scaled diagram of the Kerbol system. Maybe not as useful as the others, but this one I find quite interesting. Not that the distance between the planets is of course not at all accurate, and it's not scaled at all. They're just placed in a neat little line at whatever distance was most eye appealing.

All these graph's or charts were made by me using numbers obtained both from the wiki, from personal calculations, and from calculations done by other users.

Enjoy!!

Edited May 10, 2013 by MarcRan17
Added/corrected a few details that may have been unclear or misleading

[Itsdavyjones]

nice charts, the delta v chart is very nice

[flightmaster]

I love the final diagram, really well done!

[tavert]

Looks as if you got the transfer delta-V numbers from one of the existing maps, right? I don't know who originally created those, but some of the numbers (Dres especially, probably also Moho and Eeloo) need revision. They're quite a bit optimistic due to inclination and eccentricity. The real transfer numbers will depend on timing, such a simple graphical representation can't quite capture as much information as something like a full porkchop plot, but they should at least try to be close to the best-case numbers.

And the Eve takeoff number is too pessimistic. Judging by successful designs, it ranges from around 8000 m/s from the highest mountain to something like 10000 m/s from sea level. That's assuming efficient TWR and trajectory.

[TriggerAu]

Love the third one, very nice

[bulletrhli]

This is lovely, I downloaded them and printed them for my lovely wall of information!

[nyrath]

Outstanding work MarcRan17! The results are both attractive and useful.

I might toy with making a nomogram for delta-v, just for fun.

http://www.projectrho.com/public_html/rocket/engines.php#id--Handy_Aids

[SunJumper]

I want to point out that the maximum mass ratio for an ion craft is 2.4, making for a delta-v of 36.1km/s. Of course, you can get more by staging (actually possible with ions), but for one stage, you are stuck at 36.1km/s.

[MarcRan17]

I want to point out that the maximum mass ratio for an ion craft is 2.4, making for a delta-v of 36.1km/s. Of course, you can get more by staging (actually possible with ions), but for one stage, you are stuck at 36.1km/s.

Ah yes thank you for reminding me of that. I made the graph a while back and I had meant to correct that but yes, you are correct. With all of the standard liquid tanks (except the Oscar B and the Toroidal one) the mass ratio caps at nine, but with the aforementioned exceptions, it's something like 5.3, and with Xenon tanks it is, as you said, 2.4, which is not very high.

[SunJumper]

Ah yes thank you for reminding me of that. I made the graph a while back and I had meant to correct that but yes, you are correct. With all of the standard liquid tanks (except the Oscar B and the Toroidal one) the mass ratio caps at nine, but with the aforementioned exceptions, it's something like 5.3, and with Xenon tanks it is, as you said, 2.4, which is not very high.

The SRBS and RCS may be interesting additions, too.

[Dr Rendezvous]

I note the generally accepted 2800m/s to get into Laythe orbit from the surface, yet no matter how I try it I always need a lot more than that. Can anyone direct me to a decent tutorial on Lythe-launching that might show me how I'm messing this up?

Thanks!

[a2soup]

Nice, I especially love the phase angle diagram! I should note, however, that on the delta-v diagram (and many others I have seen), a figure of 3880 delta-v is given for getting from Kerbin orbit to Moho orbit. In my experience, this takes more like 7000 delta-v, although I'm sure you could do it for a bit less with some fancy tricks. Even then, however, it would probably take something like a Mun gravity assist for Kerbin escape and an interplanetary Eve gravity assist during a one-in-a-thousand Kerbin-Eve-Moho inclination alignment to get as low as 3880 delta-v. I encourage you to be a trendsetter and figure out how much delta-v getting to Moho actually takes, for all future delta-v charts.

But in general, a great chart. I also love the Kerbol system scale diagram.