Updated Delta-V cheat sheet?

[Taki117]

So, I've been mucking around KSP for a while and using the Cheat Sheet on the Wiki to determine how much dV is needed to get different places (Orbit specifically) and I have found that it takes far less than what the cheat sheet is showing to get into orbit. (I haven't done the exact math, but I have gotten into orbit with about 3.8km/s) Have the dV values changed with .22, or is it because I'm doing a gravity turn?

[Psycix]

Pretty sure all that stayed the same.

On another note, although you may shave off a few hundred m/s from the 4500 m/s to get to LKO, I am sceptical of your 3800 m/s to orbit claim.

[Taki117]

Pretty sure all that stayed the same.

... I am sceptical of your 3800 m/s to orbit claim.

I will post pics next time I pull it off. (Had to restart career mode a time or two and forgot to backup saves)

[Spartwo]

Jet engines?

[numerobis]

Are you using FAR?

[vetrox]

Mods?

10char

[Taki117]

YEs mods, but nothing too drastic, B9 and KSPX are the only things I use for parts, and MechJeb without autopilot. I usually set my Apoapsis at 75km.

[Taki117]

For your viewing pleasure.

Javascript is disabled. View full album

[wilt57]

4,523 delta-v to get to 75 km orbit. Sounds normal. I get to 80 km using 4,450. That's a big difference from claiming 3,800.

[Smidge204]

It's not clear where you're getting 3800m/s dV from, but I think I have an idea...

From the VAB; You start with a total dV of:

Atmosphere: 4918 m/s

Vacuum: 5804 m/s

Once in orbit:

Atmosphere: 1006 m/s

Vacuum: 1281 m/s

It's tempting to say 4918-1006=3912 and say you made it into orbit with 3912m/s dV. But that would be wrong, because the Isp for the engines transitions very non-linearly with altitude. You used 4523m/s if you go by Vacuum-rated dV, which I think is how the charts are "calibrated" since they deal almost entirely with travel in a vacuum.

Maybe. Depends on which cheat sheet you use I suppose.

=Smidge=

[numerobis]

MechJeb tracks your dV usage; look it up under the 'recorder' category. I expect you used about 4450 to 4500 m/s.

That number isn't super useful of itself when it comes to planning; it's very close if you used aerospikes, and fairly far if you used nukes, and off by a few percent otherwise.

[Superfluous J]

Yeah the cheat sheets use vacuum isp. I just ignore the atmo figures from KER on launch and when building.

Edited November 18, 2013 by 5thHorseman

[Kerbart]

MechJeb tracks your dV usage; look it up under the 'recorder' category.

Wait, what?!

[numerobis]

Wait, what?!

Click on the 'E' in an info window, switch to the "Recorder" category, select the data you seek.

[Taki117]

Yeah the cheat sheets use vacuum isp. I just ignore the atmo figures from KER on launch and when building.

Ah, this makes more sense. And here I have been using Atmo dV so that I'm always over budget (And where the 3800 claim comes from)

[Psycix]

That explains everything then