KSP and KER different DeltaV

[Daddio]

I have an assembly using an LNTR engine and five FL-T800 tanks with liquid fuel. In KER the DELTAV is shown as 11604m/s but in ksp 6285 m/s. When launched and deployed in LKO the ksp figure appears to be the deltav left. Can anyone explain why the vast difference in prediction? Thanx.

[DeadJohn]

Are you using the same sea level vs vacuum setting for the KSP display and KER?

Are you using something like "asparagus staging" where you keep the same set of engines running, but drain fuel from one tank at a time then drop the empty tank? Both KER and KSP can get confused by complex staging arrangements.

[Daddio]

Yes I am using the same setting for ksp and  KER. I have the fuel tanks stuck to each other with a central tank and four partly merged tanks. Now i'm writing this i'm thinking this might be a problem!! I'm new to all this kerbal stuff.

Edited March 17, 2021 by Daddio

[Guest]

Which one was more accurate in the end?

[Anth]

Both KER and KSP depend on the location of the root part to know how to report Deltav.

For both I recommend having the root part on the top stage.

KER is generally more accurate in my own experience, I have only found KSP being more accurate than KER in one situation which I cant remember off hand

Don't trust the KSP deltav in the following 2 cases:

• When there are tanks that have uneven amounts of LQ fuel verses OX within the one stage/tanks
• When you have changed the thrust limiter of stages where there are multiple engines.

Why? no idea