[Delta V calculations accuracy]

Quote

there is no single formula that can do this.  There is a reason the term "rocket science" is used to mean a very complex and difficult task.  I think that most people figure it out by extensive experimentation.  I studied the problem by writing a computer simulation and performing repeated simulated launches until I found what I thought was an ideal design.  The simulation involved many formulas; way more than I care to explain.

@OhioBob Thanks for the data and the nugget of criticism. I may have constructed my question poorly. Though I'm no stranger to rocket science. I was asking in terms of dV to fuel consumption and how to expend the dV efficiently in terms of flying the spacecraft. Though I appreciate the data.

[Delta V calculations accuracy]

16 hours ago, FullMetalMachinist said:

No, no, that's not it. The maneuver node code in KSP assumes instantaneous velocity change. The Tsiolkovsky equation doesn't care at all about TWR. 

That is the issue with the node predictions where the lower your TWR, the further from the "ideal" result of the node you will be. But it has nothing to do with how much dV your ship has. 

@Sans Solo, for your problem, it sounds like you're doing the math right, just that the atmosphere is tripping you up, as others have said. If you don't want to rely on a mod to do the math for you, then I would say just ignore the atmosphere part of the journey when you do your calculations. 

Pretend that you always start in low orbit, and do all the math from there, using the vacuum numbers. Then take the resulting craft, and stick it on top of a lifter that is capable of getting the whole thing into low orbit. 

@FullMetalMachinist Thanks for the answer, yeah I really want to know the whole mathematics of it before I get to use the aid mods, because I'm planning to use this to pursue rocketry as a hobby and probably as a profession too.

So I understand that the calculations would work better for orbit and factoring aerodynamics, gravity loss and vectors would be tedious. But do you have any formula I could use so that I may be able to launch my vehicle to orbit in the most efficient way? Any tips?

[Delta V calculations accuracy]

Hello guys I've been playing KSP for about 1 year and 5 months and lately I've been taking it seriously, I am currently building a rocket to the Mun and have been calculating my delta V so that I can efficiently travel there. But, unfortunately my calculations seem to be off (even if I use the Vac and ASL values for each engine/stage) and the speed indicator value is always less than what I have calculated. Is there something that I do not know yet or have forgotten to factor like aerodynamic drag?

The two formulas I use are:

The Tsiolkovksy Rocket Equation

delta V = V_Exhaust x ln( Mass_INITIAL / Mass_FINAL )

And

V_Exhaust = g (I_sp)