Delta-V map for SFS 1.5

Altaïr

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#51
That's enough now guys.

It's ok to share informations about delta-V costs (even if an information is inadequate I won't blame anyone for it, I can't say I never made mistakes myself), but that thread is supposed to be a source of help, and it's more and more derailed. Back on topic now.
 

Mooncrasher

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#53
Hi there, I'm not sure if this will be of use to you guys but in case it is, here is a basic interactive delta-v map I've made deltavmap.github.io

Let me know what you like/dislike and I might be able to change it.

Cheers.
Um, it's a very cool implementation but it's for the real world, not Spaceflight Simulator.
I think it'd be more appreciated in the (real life) Space/Rocketry/Aviation subforum.
 

Altaïr

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#56
Ok cheers. Is there something that I could change that would make it more applicable for Spaceflight Simulator? I saw some mention of scaling down the delta v requirements.
About scaling down the delta-V requirements, in theory it works, provided the solar system is scaled down by a fixed factor and the scale is perfectly respected. However it is not the case. The reduction factor in SFS is 1:20, but it's applied approximately, for some bodies the gravity is not exactly the same than in real life, so it's approximative.

The concept of an interactive map is interesting, but you could simplify it a lot. Because most bodies are not even part of SFS (at least not officially), there are no lagrangian points in SFS, and near rectilinear halo orbits are not possible, so you could remove all this because this would be of no use.

Also, there's a major problem with the way you calculate the transfers in a general way.
For example, from Earth escape trajectory, you have to provide 0.28 km/s if you want to go to Venus, and 2.06 more km/s to go to Mercury, so 2.34 km/s in total. Until now it's fine, but the problem is that if you start from Venus, a transfer to Mercury (from Venus escape trajectory) is NOT 2.06 km/s.

You can't say that "Earth to Mercury" = "Earth to Venus" + "Venus to Mercury", you have to recalculate the transfer.

Of course, that problem also exists with my map, the values are calculated assuming that you are coming from or going to Earth. Calculating a "Venus to Mercury" path on my map would give the wrong result too. That presentation is misleading.

On a picture I had no choice because representing all possible transfers would have been a nightmare (I tried, it's unreadable), but on an interactive map, you can avoid that problem, by drawing only the required transfer.

If the problem is about calculating the transfers, I can help you about that. I can give you all the formulas you will need to calculate them.

I'll explain you if you are interested. Until then, feel free to use the values from my delta-V map of course. They have been calculated accurately.
 
#57
About scaling down the delta-V requirements, in theory it works, provided the solar system is scaled down by a fixed factor and the scale is perfectly respected. However it is not the case. The reduction factor in SFS is 1:20, but it's applied approximately, for some bodies the gravity is not exactly the same than in real life, so it's approximative.

The concept of an interactive map is interesting, but you could simplify it a lot. Because most bodies are not even part of SFS (at least not officially), there are no lagrangian points in SFS, and near rectilinear halo orbits are not possible, so you could remove all this because this would be of no use.
I could strip out whatever isn't required.

Also, there's a major problem with the way you calculate the transfers in a general way.
For example, from Earth escape trajectory, you have to provide 0.28 km/s if you want to go to Venus, and 2.06 more km/s to go to Mercury, so 2.34 km/s in total. Until now it's fine, but the problem is that if you start from Venus, a transfer to Mercury (from Venus escape trajectory) is NOT 2.06 km/s.

You can't say that "Earth to Mercury" = "Earth to Venus" + "Venus to Mercury", you have to recalculate the transfer.
Agreed. Someone else just pointed this out too.

If the problem is about calculating the transfers, I can help you about that. I can give you all the formulas you will need to calculate them.
That would be much appreciated. I'm a web developer and I initially just made this map to exercise a few technologies, so I'm new to orbital mechanics.
 

Altaïr

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#58
That would be much appreciated. I'm a web developer and I initially just made this map to exercise a few technologies, so I'm new to orbital mechanics.
Ok, I'll explain you in private. Overall you will just need a few formulas, in itself it's not very complicated. The result may be very interesting if you can achieve that!
I'm busy right now, but I'll contact you as soon as I can :)
 
#59
Ok, I'll explain you in private. Overall you will just need a few formulas, in itself it's not very complicated. The result may be very interesting if you can achieve that!
I'm busy right now, but I'll contact you as soon as I can :)
Thanks for that. There's no rush. I'll plod along in the mean time and I'll report back if I'm stuck. Cheers :)
 

Altaïr

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#61
Hi, do you have a map for landing (with an engine and no parachute)?
No sorry, it's not possible to calculate a value generally speaking, because this will depend on too many things: thrust-to-weight, specific impulse, the trajectory... and drag for planets with an atmosphere!

At least you know that the delta-V needed for landing is at least equal to the orbiting velocity. When the gravity is low, the gravity losses will be minimal, so you can assume a slightly higher value plus a margin. For example the orbital velocity is 332 m/s for the Moon, so if you take a value around 450 or 500 that leaves you a good margin.
 

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#62
Hello guys!

Finally, here it is, the official delta-V map for SFS 1.5:
View attachment 40435

This map can be used to know the delta-V requirements for a particular mission. A delta-V calculator can be used then to design an optimal ship to complete the mission.

If you were used to the delta-V map under SFS 1.4, you'll notice that the transfers are slightly more demanding now. This is because the solar system scale has been raised by a factor 2.5, and the Sun is nearly 3 times more massive than before. The only exception to this is Venus because its orbit has been raised a little more, and it's now relatively closer to Earth than it was before.

Here are a few tips about how to use this map:
View attachment 40436 View attachment 40437
Those tutorials were made with the previous delta-V map, which explains that some numbers are slightly different.


Detailed explanation of the delta-V concept:

If you've never heard about delta-V, you've probably been confused by this term. "Delta-V" litterally means velocity difference. It is an abstract resource for rockets, that tells you "by how much it can make vary its velocity". For example, if your ship is moving at 1650 m/s, and then you accelerate until it reaches 1750 m/s, you've spent 100 m/s of delta-V. And some fuel aswell.
Because a rocket has a limited quantity of fuel, its delta-V is limited too. The delta-V of a rocket mainly depends on its fuel reserve. There are other factors, but I won't elaborate here.

Some calculators allow you to know precisely how much delta-V a rocket has at its disposal, this map tells you how much you need for a given mission. The combination of both allows experienced players to accurately design a ship for a particular mission.
For a fairly well skilled player how much of a margin should they consider?
 

Altaïr

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#63
For a fairly well skilled player how much of a margin should they consider?
It's difficult to give a precise value of what would be a good margin, but a margin around 10% is pretty good in my opinion, it gives some room for mistake while not making your ship excessively heavier. My policy is that a little too much is better than too little, but experience will be your better ally here.
 

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#64
It's difficult to give a precise value of what would be a good margin, but a margin around 10% is pretty good in my opinion, it gives some room for mistake while not making your ship excessively heavier. My policy is that a little too much is better than too little, but experience will be your better ally here.
Ok thank you noted
 

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#67
What would you say is a good margin for a reasonably experienced sfs player?
 

Altaïr

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#68
What would you say is a good margin for a reasonably experienced sfs player?
You asked for the same question a few months ago, check above:)
 

ASC

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#70
it seems like my mission needs... OVER 8 kilometers of delta v! Plus some extra delta-v from mars atmosphere and imperfections which means extra fuel reserve. my longest-range rocket was only able to... get at most 2.5-4 kilometers of delta v.
 

Catalyst_Kh

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#71
At Realistic level of difficulty you need 10.4 km delta V only to obtain Earth orbit. :) That is where game becomes interesting. At Normal level you just add more fuel and more engines and you will for sure have tons of extra delta V, just for any case, so you would not worry about it at all.
 

ASC

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#72
At Realistic level of difficulty you need 10.4 km delta V only to obtain Earth orbit. :) That is where game becomes interesting. At Normal level you just add more fuel and more engines and you will for sure have tons of extra delta V, just for any case, so you would not worry about it at all.
in total... 80... km/s for realistic mode?