Kerbal Engineer Redux; How do I read the stats properly?

[Pim]

I am kind of confused about the delta-v numbers when a spacecraft is seperated into multiple stages. How do I read the numbers properly to see if my spacecraft can reach a certain celestial body?

Also, I really like this delta-v map, but how can I use this one in combination with the numbers KER provides to properly build rockets?

https://steamcommunity.com/sharedfiles/filedetails/?id=1356849729

[RustyNails]

Say I wanted to go to the Mun and back. I would look at it like this

1. Return to Kerbin from Mun surface (580+310+860) = 1750 deltaV
Set Body to Mun
The actual number is lower since I will use Atmospere to reduce delta V. I would add 200 instead of 860 for a total of 1090.

2. Land from Mun orbit 310 deltaV (Plus a possible 340 If you need to change your plane)
Set Body to Mun

3. Get to Mun circular orbit 310 deltaV
Set Body to Mun

4. Mun flyby from Kerbin 860 deltaV
Set Body to Kerbin (no atmosphere)

5. Launch from Kerbin to orbit 3400 deltaV
Set Body to Kerbin (atmosphere)

As you change modes in KER you previous stages will report inaccurate numbers. Where you want to have actual physical stages is up to you. You will want some marginss for mistakes and what not.

[Sirius]

I can only tell you how I use KER.

When launching from Kerbin, your TWR should be above 1.5, if possible +2.

The last stage in the list is the first to burn, so here it is very important to have enough TWR / DV to get to orbit. For aircraft that are not supposed to go outside the atmosphere, TWR of ~1.3 is enough, I have found, as long as it stays a bit above 1.

As for the DV, I forget the numbers, but I'm sure you can look up on how much you need for any given celestial body.

Then you just add it all up (the total DV of the stages), put in a safe margin for errors / correction burns, done.

Keep in mind that you also have to adjust in case the planet you are going to has atmosphere, and read up on their respective TWR 'needs' to lift you off and into orbit.

The actual DV are, again, either experience values (so YOU know how much you need), or facts read up on the net or wikis. Or your schematics up there.

As I read that map, it is sliced into paths with each their own DV.

So you need around ~3.4k to get to Kerostationary orbit, another ~1k to intercept the moon, and so forth. Add it all up with a bit thrown in for corrections / errors, and done.

This is likely a very newbie view on things, but then so am I, and the simple "Keep TWR above 1.5, if possible above 2" has helped me greatly with getting to orbit at least.

[Pim]

Originally posted by RustyNails:

Say I wanted to go to the Mun and back. I would look at it like this

1. Return to Kerbin from Mun surface (580+310+860) = 1750 deltaV
Set Body to Mun
The actual number is lower since I will use Atmospere to reduce delta V. I would add 200 instead of 860 for a total of 1090.

2. Land from Mun orbit 310 deltaV (Plus a possible 340 If you need to change your plane)
Set Body to Mun

3. Get to Mun circular orbit 310 deltaV
Set Body to Mun

4. Mun flyby from Kerbin 860 deltaV
Set Body to Kerbin (no atmosphere)

5. Launch from Kerbin to orbit 3400 deltaV
Set Body to Kerbin (atmosphere)

As you change modes in KER you previous stages will report inaccurate numbers. Where you want to have actual physical stages is up to you. You will want some marginss for mistakes and what not.

Originally posted by |x|SiriuS|x|:

I can only tell you how I use KER.

When launching from Kerbin, your TWR should be above 1.5, if possible +2.

The last stage in the list is the first to burn, so here it is very important to have enough TWR / DV to get to orbit. For aircraft that are not supposed to go outside the atmosphere, TWR of ~1.3 is enough, I have found, as long as it stays a bit above 1.

As for the DV, I forget the numbers, but I'm sure you can look up on how much you need for any given celestial body.

Then you just add it all up (the total DV of the stages), put in a safe margin for errors / correction burns, done.

Keep in mind that you also have to adjust in case the planet you are going to has atmosphere, and read up on their respective TWR 'needs' to lift you off and into orbit.

The actual DV are, again, either experience values (so YOU know how much you need), or facts read up on the net or wikis. Or your schematics up there.

As I read that map, it is sliced into paths with each their own DV.

So you need around ~3.4k to get to Kerostationary orbit, another ~1k to intercept the moon, and so forth. Add it all up with a bit thrown in for corrections / errors, and done.

This is likely a very newbie view on things, but then so am I, and the simple "Keep TWR above 1.5, if possible above 2" has helped me greatly with getting to orbit at least.

Thanks.

Getting into orbit is not the issue, well, not always. I am currently attempting a Mün landing with a seperate mothership, like the Apollo missions. I just can never get back into Mün orbit again with the lander. Docking is no issue, I can do that.

Anyways, I'm going to use both of your tips. Here's hoping it works out.

[RoofCat]

you need to launch back to Mun orbit. Which for non atmospheric worlds with low gravity is basically low orbital speed as you turn east right away and then some 30m/s extra. So "580"m/s for Mun.
Then you need to escape Mun retrograde with ~300m/s. Done.
If you have used properly targeted nodes, your Kerbin Pe will show as 38km (or whatever your prefered reentry is) at this point. Kerbin atmosphere drag and landing chutes will do the rest. 900m/s is all you need to return from Mun. And some heat resistance and proper balance. Local Mun TWR isn't even relevant as long as it is higher than 1.

Or you can do it with powered landing. In which case it will be all the way backwards. You will save some on drag slowdown, but also waste some as landing with engines on high g worlds isn't as "easy" as launching. Even more so with ships still having full tanks (for that very landing). So rather close delta v values anyway.