Delta-V map for SFS 1.5

Orion

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#78
How would I use this to plan round trips? Like, would mars-earth require less delta-V?
 

Idkgeek

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#79
How would I use this to plan round trips? Like, would mars-earth require less delta-V?
It wouldn't require less in the sense that you will need to slow down alot more heading to earth. So LMO to LEO would require the same delta v as the reverse.
 

Orion

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#80
It wouldn't require less in the sense that you will need to slow down alot more heading to earth. So LMO to LEO would require the same delta v as the reverse.
Cool, Thanks!
 

Altaïr

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#82
This is lovely. Is there a map for hard mode with 50km LEO?
Oh, nice to see you! How are you? :)
Unfortunately I didn't make a map for hard/realistic mode, and to be honest even this one is outdated (even if it's far from being wrong) because orbits were circular when I did it.
If you use the PC version you can quickly calculate your own transfers with ANAIS though. Used in combination with Warpinator to switch quickly from place to place it should be even faster.
 

Altaïr

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#84
TWR_earth * g_earth / g_body
Yes, exactly :)

Also, may I know why the Galilean Moons surface gravity is that big? I think it's around 1.2-1.7 m/s2 ish.
You're right, the map is outdated. The data was correct once ago (which made Ganymede surprisingly hard to land on), but Stef lowered their gravity to make them more realistic at some point.
 

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#85
Yes, exactly :)


You're right, the map is outdated. The data was correct once ago (which made Ganymede surprisingly hard to land on), but Stef lowered their gravity to make them more realistic at some point.
I remember that ganymede was the hardest destination to land on with it's high gravity, mountanous terrain and location near jupiter
 

Altaïr

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#86
I remember that ganymede was the hardest destination to land on with it's high gravity, mountanous terrain and location near jupiter
Yeah, I remember, this is what forced me to use a Valiant engine for my lander when I made a Galilean Tour. A Kolibri was lighter but didn't have enough thrust.
 

Altaïr

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#91
Okay, I just saw it was for 1.5 and I thought the captured asteroid was in this update! Sorry.
It's fine, don't worry. Actually the problem is worse than before because orbits have eccentricity now. When I made that map, all orbits were perfectly circular, so the calculation was simple. Now the problem is that, as the asteroid orbit is very elliptic, the transfer cost will depend on the position you aim for on the orbit, so I can't give a unique answer as before.
 

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#92
It's fine, don't worry. Actually the problem is worse than before because orbits have eccentricity now. When I made that map, all orbits were perfectly circular, so the calculation was simple. Now the problem is that, as the asteroid orbit is very elliptic, the transfer cost will depend on the position you aim for on the orbit, so I can't give a unique answer as before.
Could you give a range? like 200-250m/s? or just give the worst case scenario?
 

Altaïr

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#93
Could you give a range? like 200-250m/s? or just give the worst case scenario?
A range would make it harder to read in my opinion. I've tried to make more complex maps, and my experience is that it quickly becomes messy. I think the best move would be to give a worst case scenario, because I know that many people just read the numbers without considering practical questions (many would probably not even understand why there's a range).
The real problem is that I lack of time to be honest, but if I can find a moment I can consider updating it yes.
 

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#94
A range would make it harder to read in my opinion. I've tried to make more complex maps, and my experience is that it quickly becomes messy. I think the best move would be to give a worst case scenario, because I know that many people just read the numbers without considering practical questions (many would probably not even understand why there's a range).
The real problem is that I lack of time to be honest, but if I can find a moment I can consider updating it yes.
That makes sense, but how much does the delta-V requirements change from best case scenario to worst case scenario?
 

Altaïr

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#95
That makes sense, but how much does the delta-V requirements change from best case scenario to worst case scenario?
It depends, but probably not much in most cases. For the asteroid for example, you can see from the map that you need 664 m/s to raise your apogee to the Moon level, and 17 m/s more to reach the Earth's SOI limit, so 681 m/s. The asteroid is between those, so both best case and worst case are in this range (664 to 681 m/s).

The most worrying situation would be a transfer from Earth to Mercury: Mercury's orbit is noticeably elliptic, and the difference would be much more. I made those calculations once, depending on whether Mercury is at the perihelion or the aphelion:
Screenshot_20240328_194402_Chrome.jpg Screenshot_20240328_194420_Chrome.jpg
The final results is in the lower part, the rest is intermediate calculations.

You can see that there's more than 500 m/s between both situations. It could also be confusing because the best case (when Mercury is at the perihelion) corresponds to when Mercury is the farthest from Earth, so the transfer from Earth is the most expensive. Then the insertion around Mercury is the cheapest, so overall it's better, but without clear indication about it I'm pretty sure that 99% would get it wrong.
That's the main problem, even if just giving the worst estimate would guarantee your success.