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specific calculations?


pshimko27
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hey guys, so i have been playing kerbal space program for a while now, almost 4 months, ive been to moho eve duna mun minmus and deep space, would there be anyway to calculate things like DN and AN or orbeth? i need these for a challenge on the discord patched nonics (basically only l1 tracking station)

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9 hours ago, pshimko27 said:

hey guys, so i have been playing kerbal space program for a while now, almost 4 months, ive been to moho eve duna mun minmus and deep space, would there be anyway to calculate things like DN and AN or orbeth? i need these for a challenge on the discord patched nonics (basically only l1 tracking station)

The Oberth effect is probably the easiest to calculate.  You'll need the vis-viva equation and a decent working knowledge of algebra, but it obviously can be done:  the ship flies, after all.

Longitude of Ascending Node (which I assume is what you meant; how large the ascending node is is simply your inclination angle, but where it is is the longitude) is much more difficult to do.  The problem is that in reality, LAN is defined based on a 'fixed' (that's only relatively, locally, and temporarily true, but it works for navigation for now because of the scales involved) point in space, and the only 'fixed' points in space are the stars.  KSP, on the other hand, doesn't have stars.  It has a pretty skybox, of course, but that skybox is essentially painted on the face of the universe for aesthetics and without any consideration for navigation.  In other words, it has no fixed orientation, which means that you cannot take repeatable, reliable bearings from stars.

That said, there may still be ways to help you:  I find it difficult to believe that there would be an impossible challenge on the Discord without someone else figuring that out and announcing it.  What is the challenge?

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5 hours ago, Zhetaan said:

The Oberth effect is probably the easiest to calculate.  You'll need the vis-viva equation and a decent working knowledge of algebra, but it obviously can be done:  the ship flies, after all.

Longitude of Ascending Node (which I assume is what you meant; how large the ascending node is is simply your inclination angle, but where it is is the longitude) is much more difficult to do.  The problem is that in reality, LAN is defined based on a 'fixed' (that's only relatively, locally, and temporarily true, but it works for navigation for now because of the scales involved) point in space, and the only 'fixed' points in space are the stars.  KSP, on the other hand, doesn't have stars.  It has a pretty skybox, of course, but that skybox is essentially painted on the face of the universe for aesthetics and without any consideration for navigation.  In other words, it has no fixed orientation, which means that you cannot take repeatable, reliable bearings from stars.

That said, there may still be ways to help you:  I find it difficult to believe that there would be an impossible challenge on the Discord without someone else figuring that out and announcing it.  What is the challenge?

the challenge is patched nonics, basically you have to go to mun (done) and back with a L1 tracking station and no kerbal engineer, the hard mode is to go to duna and back with a L1 tracking station (almost done), and the super hard mode ("impress me") im gonna try to get to either moho or dres and back, and can i have the formulas?

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If by "Obeth" you mean the amount of DV you need to change your peri or apoapsis, I usually use the instantaneus orbital speed equation [Orbital Speed]

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Given your ship be positioned at the periapsis or apoapsis (r=PE+R or AP+R), and you can calculate your actual semi-major axis (a = (PE+AP+2R)/2) , then you can obtain how much speed would you have to add or remove from your PE or AP to change the other one...

For example, you are at periapsis of 70km on Kerbin Orbit with AP of 100km ... And you want to circularize and bring your AP down to 70km:

Kerbin radius R = 600km

Kerbin Standard gravitational parameter \mu = 3.5316000×1012 m3/s2

Your actual semi-major axis a = (70+100+1200)km/2 = 685km

Then your actual speed at PE in your actual orbit is:

Vi~ sqrt(3.53e12*(2/670e3 - 1/685e3)) = 2320m/s

Given that your PE will not change if you change your speed fast enough at PE, only AP will change, then the speed that you should have at PE for a circular orbit can be calculated given the semi major axis a= (70+70+1200)km/2 =670km

Vf~sqrt(3.53e12*(2/670e3 - 1/670e3)) = sqrt(3.53e12/670e3) = 2295m/s

Which means that you would need to reduce your speed from 2320m/s to 2295m/s burning retrograde at PE, consuming 25 m/s of DV

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17 hours ago, pshimko27 said:

the challenge is patched nonics, basically you have to go to mun (done) and back with a L1 tracking station and no kerbal engineer, the hard mode is to go to duna and back with a L1 tracking station (almost done), and the super hard mode ("impress me") im gonna try to get to either moho or dres and back, and can i have the formulas?

Certainly.

The general calculations, or at least an example of them, can be found here.  A more practically useful step-by-step demonstration for Duna, which you can (and should!) use to evaluate your Duna trip so you can get a feel for how it works, is here.  Also note that the second link is a part of a series of KSP Let's Do The Math videos, and the next planet in that series is Moho, so you may find it especially useful.

The equations used in the video all follow from the vis-viva equation, which is as follows:

v2 = μ[(2 / r) - (1 / a)]

Where:
v = instantaneous velocity at that point of the orbit,
μ = standard gravitational parameter for the primary body (it is Kerbin for the escape, the Sun for the transfer, and Duna for the capture),
r = orbital radius at the point of the burn, and
a = the semi-major axis of the orbit.

Calculating these for your parking orbit and your transfer orbit, then subtracting to get the difference, will yield the burn delta-V.  You'll need to do it multiple times, considering each leg of the trip, but that's all fairly straightforward--especially if you have a good grasp of algebra.  The nuance is in selecting where and when to burn.  I understand that to be part of the challenge, so I won't deprive you of a chance to figure it out for yourself.

 

 

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