Delta-V questions

[erik9631]

Hello.

I am trying to build a fuel efficient craft. But my understanding of delta-v and how it works is flawed. I am using mechjeb.2.0

So here are my questions:

1. 
Does anyone know what does the time represent? Is it the total burn time? How is it related to Delta-V

2. Does Delta-V calculation account for weight? Do the delta-v requirements for maneuvers increase as the weight goes up?

The issue is that I managed to get high delta-V which was around 6K on my previous rocket, but once leaving the atmosphere I had issues hitting stable orbit, because the engine was simply not strong enough to do it in a reasonable amount of time, so I got trashed by gravity.

I would appreciate if someone explained all this in detail. Thanks.

Edited July 25, 2017 by erik9631

[WanderingKid]

I can't speak to MechJeb, but I can help you out with Delta-V (dV for short).

First off, the equations and the like I'll be referencing can most easily be found here, though there are plenty of others if you google ksp delta v calculation:

http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design

dV is a function of thrust over time.  It's a Delta to your velocity (or vector, depending on thought), thus V.  This isn't directly equated to a burn time, as you can burn at different rates for less, or more, change per second.  However, there is a max-throttle burn time and/or a at current throttle burn time, which is the time number you're seeing above.  Which one it is in MJ, I'm not sure.

Now, dV is calculated by your wet mass, your dry mass, and the ISP (think gas milage when starting to ease your mind around the idea) of the engine(s) involved, using the gravity of the world the ISP was rated on as a constant to determine Exhaust Velocity.  It's a log equation also known as Tsiolkovsky equation to figure out how much vector you can change on your current ship as a factor of the fuel you'll burn going from wet (heaviest, worst mpg) to dry (lightest, best mpg). For our purposes, it's a plug and play function, we just need a calculator.

Divide the wet mass of your ship by the dry mass (Example: 10t craft with 6t of fuel), so 10/6.  Use the ln function (Natural Log) on your calculator against the result of that.  Then multiply it by the ISP listed in game (we'll use 320 for the vacuum ISP for the moment) and then by 9.81, the gravity constant of where the ISP was rated from.

So, 10/6 =~ 1.667.  ln(1.667) = .5108.  * 320 * 9.81 = 1603.58.  So, roughly 1,603.58 m/s of dV.  This means you can adjust your velocity by that much with that fuel and engine.  So if you had an orbital speed of around 1,603 m/s, you could burn off all your fuel and fall like a brick, or use a little over half of that to transfer burn to Mun (which costs ~850).

Finally, the # that's getting you during your circularization burn (achieving apoapsis and raising periapsis to NOT fall back into the atmosphere) is the TWR, or Thrust to Weight Ratio.  This is done via the kN (KiloNeutons) rating on the engines you're burning.  Typically a 6,000+ dV is done with Nukes, and these are notorious for not having TWR worthy of fast maneuvers.  They're almost specifically used once in orbit and often over multiple burns at periapsis to get your apoapsis to the required height.  The math for TWR is also relatively simple once you have all the #'s to plug into the equation, and that DOES change as you burn fuel, you'll have a higher TWR the lighter the craft overall is.

I suggest you check out this wiki page for more information on understanding TWR:

http://wiki.kerbalspaceprogram.com/wiki/Thrust-to-weight_ratio

[Jas0n]

The time is the total burn time. It isn't really related to delta-v.

The delta-v takes into account mass, as in that if you have 1000m/s of delta-v, you can increase your velocity by 1000m/s when you're in orbit. The problem you're having is that your TWR is too low, as @WanderingKid explains.

[Kelderek]

1. Not sure on MechJeb, but that is most likely the total burn time available based on your current throttle setting and active engine(s).

2. The beauty and real value of Delta-V is that it is always the same for a given maneuver regardless of what your rocket looks like.  This means that weight does not affect the amount of Delta-V you need for a maneuver like reaching orbit from the surface of Kerbin, but weight and mass DO matter a great deal in calculating the Delta-V of your rocket.  If a 20 ton rocket and a 200 ton rocket both achieve the same orbit from the same launch site then they both used the same amount of Delta-V for the maneuver.

If your engine was not strong enough then you have an issue with Thrust to Weight Ratio (TWR) and may not have a Delta-V problem at all.  The TWR must always be above 1 or gravity will get the better of you.  There is a sweet spot for TWR when launching on Kerbin, the idea is to have enough TWR to counter gravity well enough, but not too much that aerodynamic drag becomes a problem.  A launchpad TWR of 1.5 give or take should be sufficient.  If your rocket has multiple stages, you want to make sure that each stage has a TWR > 1 also.  Those sliders you see on MechJeb are to allow you to adjust your altitude to see how it affects your stats like TWR and Delta-V.  Those stats change with altitude because all of the engines in KSP (and IRL) vary in efficiency and power from being in an atmosphere to being in a vacuum, with the vacuum numbers generally being measurably better.  Some engines have horrible thrust at sea level but get much better at high altitudes or in a vacuum.  Likewise, the specific impulse (ISP, a measure of engine efficiency) usually improves as you gain altitude and that will improve your Delta-V as your engine has an easier time burning its fuel (less or no atmospheric pressure to fight against the exhaust coming out the back).

[erik9631]

Okay. I would like to thank everyone for your answers.

But to clear up confusion, I have to ask.

11 minutes ago, WanderingKid said:

I can't speak to MechJeb, but I can help you out with Delta-V (dV for short).

First off, the equations and the like I'll be referencing can most easily be found here, though there are plenty of others if you google ksp delta v calculation:

http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design

dV is a function of thrust over time.  It's a Delta to your velocity (or vector, depending on thought), thus V.  This isn't directly equated to a burn time, as you can burn at different rates for less, or more, change per second.  However, there is a max-throttle burn time and/or a at current throttle burn time, which is the time number you're seeing above.  Which one it is in MJ, I'm not sure.

Now, dV is calculated by your wet mass, your dry mass, and the ISP (think gas milage when starting to ease your mind around the idea) of the engine(s) involved, using the gravity of the world the ISP was rated on as a constant to determine Exhaust Velocity.  It's a log equation also known as Tsiolkovsky equation to figure out how much vector you can change on your current ship as a factor of the fuel you'll burn going from wet (heaviest, worst mpg) to dry (lightest, best mpg). For our purposes, it's a plug and play function, we just need a calculator.

Divide the wet mass of your ship by the dry mass (Example: 10t craft with 6t of fuel), so 10/6.  Use the ln function (Natural Log) on your calculator against the result of that.  Then multiply it by the ISP listed in game (we'll use 320 for the vacuum ISP for the moment) and then by 9.81, the gravity constant of where the ISP was rated from.

So, 10/6 =~ 1.667.  ln(1.667) = .5108.  * 320 * 9.81 = 1603.58.  So, roughly 1,603.58 m/s of dV.  This means you can adjust your velocity by that much with that fuel and engine.  So if you had an orbital speed of around 1,603 m/s, you could burn off all your fuel and fall like a brick, or use a little over half of that to transfer burn to Mun (which costs ~850).

Finally, the # that's getting you during your circularization burn (achieving apoapsis and raising periapsis to NOT fall back into the atmosphere) is the TWR, or Thrust to Weight Ratio.  This is done via the kN (KiloNeutons) rating on the engines you're burning.  Typically a 6,000+ dV is done with Nukes, and these are notorious for not having TWR worthy of fast maneuvers.  They're almost specifically used once in orbit and often over multiple burns at periapsis to get your apoapsis to the required height.  The math for TWR is also relatively simple once you have all the #'s to plug into the equation, and that DOES change as you burn fuel, you'll have a higher TWR the lighter the craft overall is.

I suggest you check out this wiki page for more information on understanding TWR:

http://wiki.kerbalspaceprogram.com/wiki/Thrust-to-weight_ratio

Since dV is a function of thrust over time, do you not think that what MJ shows is the time it takes to achieve the delta shown? It would make sense to me. It would also explain why the time decreases with better thrust to weight ratio.

 

@Kelderek

Thank you for mentioning the TWR. It was 0.35 which is a complete joke.

[Kerbal101]

I would begin with engines, all engines have different priorities - one trade power for economy(upper stage!), other trade economy for power (boosters!), third type trades mass and power for economy (nukes!). The best engines, are engines that excel in different disciplines. Every engine has it uses... Every situation has priorities... Where you don't need power (space!), you need economy. Where you don't need economy, you need power (high G/atm. planets).

TWR measures is how powerful your rocket is, compared to its weight. Engine thrust affects that. Increasing gravitation and atmosphere thickness will decrease TWR, all rocket engines have a worse "sealevel thrust" because of that. Powerful engines usually have bad economy though.
Anything with TWR < 1 can't carry its own mass and thus won't be able to fight gravity. But sometimes fighting gravity is not needed: a stage 1 could just have priority in TWR and shoot the rocket upwards (gain sufficient vertical speed), and then the other stage fires horizontally - and doesn't need to fight gravity much, just have enough time to reach the horizontal speed.

ISP measures economy, how efficient the engine will exchange the fuel for energy. Space maneuvers is where its best put at, on the planets ISP get overrulled by TWR - since if you're efficient but weak, you ain't going nowhere.

deltaV is how much velocity the vehicle can change. Its product of ISP, fuel and nonzero TWR (ideally, in vacuum).
Adding weight (equipment, crew etc), more gravity gravity, thicker atmosphere - will decrease deltaV. Adding more engines+fuel (in right balance), dropping used fuel cans and unnecessary modules will increase deltaV.

In space, the priority is on ISP and sufficient deltaV to reach the goal. Gravity does affect the performance, but its more advanced topic (see Oberth effect and slingshots). But when "not in orbits" (aka "exposed to gravity"), the priority is on sufficient TWR and enough deltaV instead of ISP.
 

How I calculate deltaV?.. When designing vehicles, I use KER to do the math and calculate approximate value for the vehicle and stage.
But to guess how much I need, I just send probes and plot maneuvers to targets. That "m/s" value to perform maneuver - is deltaV.
KER also has an in-flight "stage deltaV", which is also perfect to determine the requirements for descend and ascend from bodies too by just substracting "after" from "before". So, I have my own deltaV map for things, its much more fun.   I hope something is useful for you here, @erik9631  

[Foxster]

3 hours ago, erik9631 said:

Since dV is a function of thrust over time, do you not think that what MJ shows is the time it takes to achieve the delta shown? It would make sense to me. It would also explain why the time decreases with better thrust to weight ratio.

That time on the MJ screen is how long the stage will burn at full throttle. Personally I find no use in it. The important information for me is the dV and TWR (vac and atmo). 

Edited July 25, 2017 by Foxster

[WanderingKid]

2 hours ago, erik9631 said:

Since dV is a function of thrust over time, do you not think that what MJ shows is the time it takes to achieve the delta shown? It would make sense to me. It would also explain why the time decreases with better thrust to weight ratio.

TWR increases as you burn fuel and lower weight.  Think of it as if you tossed a fuel tank overboard... your TWR is already better even if you're not going as far.

dV isn't actually a function of thrust over time, momentum change is.  dV is a measure of how much you can change overall, I misspoke above, apologies, I got caught up in the TWR vs. dV discussion in my head.

Most likely the time is based on burn times, but what burn time I can't tell you (full burn, current throttle, all stages, etc), as I don't use MJ.  The part that truly matters for burn time is early in your 'weight' you'll need to burn longer to achieve some amount of dV instead of later, when you're lighter and your TWR is improved.

[Vanamonde]

This question about how to play the game has been moved to Gameplay Questions. 

[artwhaley]

Technically you're correct in that last question.   The time number IS the amount of time you would have to burn at full throttle to achieve the indicated delta-v... because it's showing the amount of time the stage can burn at full throttle and the delta-v of the stage.   

But as people pointed out above - that time number isn't particularly useful to you.  The actual delta-v and the TWR of your rocket are all that really matter to you from that window. 

[Aegolius13]

10 hours ago, erik9631 said:

Since dV is a function of thrust over time, do you not think that what MJ shows is the time it takes to achieve the delta shown? It would make sense to me. It would also explain why the time decreases with better thrust to weight ratio.

I would assume that the burn time is going down because you're either (1) adding more engines, which increases your fuel burn rate, or (2) removing fuel.  Both of those changes would increase your TWR, but mostly likely lower your delta-v (unless you were talking about engines with different specific impulses).  

Total burn time and total delta-v can be related, but not in a particularly useful way for gameplay.  Delta-v is change in velocity, which is equivalent to the to the cumulative amount of acceleration you perform over the course of a burn.   In a typical stage, of course, acceleration is not constant - since your rate of acceleration increases as you lose fuel mass and your TWR increases.  You could determine your total delta-v by drawing the area under the curve of your acceleration/time function (or, take the integral using calculus).  But that is what the Rocket Equation already does, and what MechJeb does when reporting a delta-v figure.  

[Streetwind]

13 hours ago, erik9631 said:

Hello.

I am trying to build a fuel efficient craft. But my understanding of delta-v and how it works is flawed.

Welcome to the forums  

Building efficient rockets helps you a lot in the game - building it correctly is just as important as flying it correctly. So that's a good goal to aim for. However, dV alone is not necessarily the key indicator for that kind of thing. An efficient rocket may have a lot of dV, but not every rocket with a lot of dV is efficient.

Instead - or rather, in addition - you may want to learn about mass fractions, and examine how your rockets fare in terms of that. It's a number closely related to dV, since it is a part of the Rocket Equation, but it's much more relevant in the construction process.

[OhioBob]

23 hours ago, erik9631 said:

I am trying to build a fuel efficient craft.

The first thing you have to do is define "efficient".  Efficiency can mean different things.  For instance, do you want to perform a particular thing using the least amount of delta-v, or do you want to design a vehicle that can complete a particular task using the smallest package, or do you want to complete the task for the least cost?  How you answer that question will drive your design.

For example, when designing a launch vehicle, many beginners believe they are being most efficient when they reduce the amount of delta-v it takes to attain orbit.  But if you are looking at it on a cost basis, that's a big mistake.  Getting to orbit using as little delta-v as possible requires using a high TWR to reduce the gravity loses.  But attaining a high TWR means using big expensive engines.  You can reduce cost by trading in those big expensive engines for smaller cheaper engines and a lower TWR.  Having a low TWR means the gravity losses will be greater, so you'll have to add some propellant to give the rocket more delta-v to overcome the greater losses (propellant is cheap compared to engines).  These changes will result in a launch vehicle that is less efficient in terms of delta-v to orbit, but it will reduce the cost per ton of useful payload delivered to orbit.  When you are playing a career game, cost efficiency in generally one of your most important considerations.

[Spricigo]

On 25/07/2017 at 2:49 PM, erik9631 said:

I am trying to build a fuel efficient craft.

Everything that OhioBob said. And also: for what? 

An efficient lifter and an efficient interplanetary stage will have very distinct characteristics.

 

*by whatever parameter

[DeadJoe]

On 26/07/2017 at 3:54 AM, Kerbal101 said:

KER also has an in-flight "stage deltaV", which is also perfect to determine the requirements for descend and ascend from bodies too by just substracting "after" from "before". So, I have my own deltaV map for things, its much more fun.   I hope something is useful for you here, @erik9631  

Do you mean, this is a way of figuring out how much dv is needed to actually land on a body (let's say Mun) , or just the burn from orbit to where you want to land?

Can you please elaborate on the subtracting the "after" from "before" thing, not sure what you mean there.

[Spricigo]

33 minutes ago, DeadJoe said:

Do you mean, this is a way of figuring out how much dv is needed to actually land on a body (let's say Mun) , or just the burn from orbit to where you want to land?

Can you please elaborate on the subtracting the "after" from "before" thing, not sure what you mean there.

No.  There is several ways to figure out that.  

Trial and error,  doing the math,  look in a deltaV map,  using a mod. 

Which one interested you? 

[DeadJoe]

29 minutes ago, Spricigo said:

No.  There is several ways to figure out that.  

Trial and error,  doing the math,  look in a deltaV map,  using a mod. 

Which one interested you? 

I do use ker, (and plenty of other mods) I'm just getting my head around what everything means and how I can use the info to know if what I've built is going to work. 

I don't use any auto pilot stuff, I like to turn and burn on my own. So for now, anything that will give me a read out of whether or not I have the fuel for a landing would be nice. Otherwise I'll trial and error and take note of the numbers in ker, and use it to do the math.

[Spricigo]

1 hour ago, DeadJoe said:

I do use ker, (and plenty of other mods) I'm just getting my head around what everything means and how I can use the info to know if what I've built is going to work. 

I don't use any auto pilot stuff, I like to turn and burn on my own. So for now, anything that will give me a read out of whether or not I have the fuel for a landing would be nice. Otherwise I'll trial and error and take note of the numbers in ker, and use it to do the math.

KER can be a bit overwhelming,  lots of info.  May take a bit of time to figure out how to setup in a way that you understand and like.  

In any case there is several ways KER may present your deltaV budget (I like deltaV C/T,  where C refer to current stage and T for total).

 To know how much is required to land in a celestial body you may take a look at a deltaV map, keep in mind that your first attempts will probably cost more,  given the piloting errors. 

[DeadJoe]

46 minutes ago, Spricigo said:

KER can be a bit overwhelming,  lots of info.  May take a bit of time to figure out how to setup in a way that you understand and like.  

In any case there is several ways KER may present your deltaV budget (I like deltaV C/T,  where C refer to current stage and T for total).

 To know how much is required to land in a celestial body you may take a look at a deltaV map, keep in mind that your first attempts will probably cost more,  given the piloting errors. 

DeltaV map, nice one.

I've been away from ksp for a couple of years and I used to just play stock, so yeah, not new to the game...just the whole modding thing and the amount of info I now have.

I used to just bang things together and see how it went, revert and try again. So I'm taking a more educated approach this time round.

Appreciate the help bud, cheers 

[Kerbal101]

7 hours ago, DeadJoe said:

Do you mean, this is a way of figuring out how much dv is needed to actually land on a body (let's say Mun) , or just the burn from orbit to where you want to land?

Can you please elaborate on the subtracting the "after" from "before" thing, not sure what you mean there.

Yes, exactly. You go into orbit and you start plotting a maneuver.
The m/s value is exactly the deltaV, which you can (should ) write down and use when designing vehicles.
 

The "after" and "before" method comes from KER in-flight ability to display your current stage and total deltaV.
So you write down for example "total deltaV" value before maneuver, then you do maneuver and write the "total deltaV" again.
Then you subtract the "before" from "after" - and you get how much you spent.

This is the best method IMHO, because its very practical and gives you ability to explore yourself
However, you must know that several factors influence deltaV - reducing required amount, so its very good to round the value up and write down from which side and clock direction you approach the planet.
For example, burning closer to the gravity source - reduces deltaV requirement. Also you could end accidentally sling-shoting.
Clock direction of your travel can be determined when looking from above

Here is the video to illustrate.
The values are:
- from Jool counterCW 1.5km/1.5km to Val 100k flyby from behind+counterCW is 1900 dV.
- Val circularization to 100k/100k orbit from behind+counterCW is 900 dV.

Also, the Jool's atmosphere ends around 210km (this can be determined by crashing a probe into it). Acceleration from that lower point to Val would cost less.
This is to illustrate why writing down altitude and approach directions is important. 

The "deltaV map" is not something to rely upon, because it does not include the directions and includes approximated values.

But I personally don't use it, because its presence rises big question of "who gave it to kerbals" and "how kerbals took possession of it".

 

6 hours ago, Spricigo said:

No.  There is several ways to figure out that. 

I am pretty sure that DeadJoe addressed me in his question with "do you mean".
I see that you are trying to help , but please don't hijack the questions like that, that was not nice. Thank you

[Foxster]

My personal preferred method for figuring out the dV I need is to use this dV calculator: https://13375.de/KSPDeltaVMap/

You click where you are starting at until it shows a rocket, then click on your destination to show a flag. dV required is shown at the top. 

I then build the craft with a dV safety margin to allow for messing things up. I really don't see the point to building a craft with such a narrow dV margin that you risk the mission. 

No maths needed. 

[Spricigo]

7 hours ago, Kerbal101 said:

I am pretty sure that DeadJoe addressed me in his question with "do you mean".
I see that you are trying to help , but please don't hijack the questions like that, that was not nice. Thank you

really, really , really don't get why did you think my post(s) was not nice.

In no way I implied anything about what you said or your method. I just get that DeadJoe expressed surprise about that fact that is possible to figure out how much deltaV is necessary to land in a given celestial body. (and maybe that is where the confusion arise, I read "there is a way to ..." when he said "this is...") and in the intent of offering help to a fellow player I pointed out that not only one method exist, but several and asked "which one interested you?" And I think I provided information that may be relevant for him and for someone else that just happens to be reading that thread trying to figure out something similar.

So, maybe bringing attention that I misinterpreted his post (or your) and what I get wrong is understandable,  even a opportunity for me to learn something. But using the word "hijack" was not nice.

 

9 hours ago, Kerbal101 said:

This is the best method IMHO, because its very practical and gives you ability to explore yourself

I think the major advantage is that the result are tailored to your own preference. If we take the tool Foxster presented, it list the deltaV cost from low orbit of Mun (14km) to the surface as 640m/s, but you may prefer, for whatever reason, use a different orbit and the deltaV cost will divert (even if by small amounts).

 

9 hours ago, Foxster said:

I then build the craft with a dV safety margin to allow for messing things up. I really don't see the point to building a craft with such a narrow dV margin that you risk the mission.

Well, the point may be the challenge. Or the fact that people usually don't really think they will mess things up. Or they consider that messing thing up once in a while is unavoidable even with a safety margin and the better approach is just accept it.

I can see the point...but usually I'm not comfortable using such narrow margins myself.

[Kerbal101]

31 minutes ago, Spricigo said:

really, really , really don't get why did you think my post(s) was not nice.

In no way I implied anything about what you said or your method. I just get that DeadJoe expressed surprise about that fact that is possible to figure out how much deltaV is necessary to land in a given celestial body. (and maybe that is where the confusion arise, I read "there is a way to ..." when he said "this is...") and in the intent of offering help to a fellow player I pointed out that not only one method exist, but several and asked "which one interested you?" And I think I provided information that may be relevant for him and for someone else that just happens to be reading that thread trying to figure out something similar.

So, maybe bringing attention that I misinterpreted his post (or your) and what I get wrong is understandable,  even a opportunity for me to learn something. But using the word "hijack" was not nice.

Sorry, but hijacking the conversation is exactly what you did and its exactly what I stated.  DeadJoe has quoted a piece of my post and asked to elaborate me on it, but you neither gave me a chance to answer by answering that quick, nor you stated anywhere in your response that that is your opinion, your version or you point of view. From what I see, your English skills are sufficient enough to understand that, so please that was not nice, not cool. If you fail to see that too, then well, there is little to discuss then.

About deltaV map, @Spricigo, have you asked yourself where kerbals would get it themselves?   For example, they could do the gravity readings on planets using remove scanning (the planet info tool inside DSN) - which allows to calculate TWR manually: for example, if kerbals know that Kerbin has 1.0G and Mun ~0.2G - they can say that a rocket standing on the ground of Kerbin with 1 TWR - would have 5 TWR on Mun (since gravity is 5 times weaker). But how would they get their hands on deltaV map?.. Kraken? Kerbal god?  
This is why I measure it manually like demonstrated and it does not fall into "trial and error" category because their DSN can predict it before maneuver is executed - its more like "practice", pretty inline with career mode. The deltaV map gives away much, way too much ... fun?

Edited July 27, 2017 by Kerbal101

[DeadJoe]

Sorry kerbal101, I didn't even check who it was I quoted. My question was aimed at you so I do apologise. Your response has helped a lot and will definitely check that video out after work today.

In saying that, I have enjoyed reading what others have said, also very helpful. I'm sure responding to my questions was done with the best intentions,  but can see why it would irritate someone if they responded without giving the quoted person a chance to reply.

All good guys, really appreciate it. If one of the biggest problems here is too many people trying to help someone, then I think we're doing OK as a community. I not sure other communities/forums could claim such a thing.

 

 

[Spricigo]

16 hours ago, Kerbal101 said:

About deltaV map, @Spricigo, have you asked yourself where kerbals would get it themselves?   For example, they could do the gravity readings on planets using remove scanning (the planet info tool inside DSN) - which allows to calculate TWR manually: for example, if kerbals know that Kerbin has 1.0G and Mun ~0.2G - they can say that a rocket standing on the ground of Kerbin with 1 TWR - would have 5 TWR on Mun (since gravity is 5 times weaker). But how would they get their hands on deltaV map?.. Kraken? Kerbal god?  

 I wonder why my opinion in this matter should be relevant.  And think we are going a bit out of topic there (a good subject for general discussion,  I suppose).  But in any case I gladly share my opinion about it. 

As I see KSP universe is pretty much a simplified version of our own.  And  kerbal are pretty much the KSP equivalent to humans. 

So,  since in our universe we had the maths to deal with celestial mechanics and astronavigation way before we had spaceships,  I expect Kerbals to have a good mathematical repertoire to map the way to the space. 

They didn't got their deltaV map from the Kraken or a Kerbal God.  They science it into existence, built it with kerbal ingenuity much like we got the requeriment for the spacecraft we send across vast distance all over the solar system and beyond. (because you can science anything! ). 

I think there was kerbals like Johannesburg Kerman,  Isaac Kerman,  Pierre-Simon Kerman, Robert Hutchinson Kerman, Robert Albert Charles Kerman,  Hermann Kerman,  Konstantin Kerman...and they made a lot for Kerbal astronautics much before Jebediah even dreamed to be an astronaut. 

16 hours ago, Kerbal101 said:

This is why I measure it manually like demonstrated and it does not fall into "trial and error" category because their DSN can predict it before maneuver is executed - its more like "practice", pretty inline with career mode. The deltaV map gives away much, way too much ... fun?

Again,  my opinion should not be relevant,  but since you asked here it go:

Is one of several methods that works.  But I can't say I share the enthusiasm to fly a vessel only to measure something I can easily calculate* in the comfort of Mission Control. Neither say that someone that prefer to look at an deltaV map is getting less fun. 

*yes, I often do calculations with pen&paper to design a vessel/mission. But for convenience and error avoidance a RPN,  stack-based calculator is preferred. 

 

Edited July 28, 2017 by Spricigo