How to calculate any ships available Delta V?

[inigma]

How can I find out how much d-v my ship can put out? I'd like an easy way to know if my ship will have enough d-v to get somewhere and back before I head out. It'd be kinda cool if in addition to fuel values if Resources showed you how much d-v you have left to burn.

Edited June 12, 2013 by inigma

[Elsig]

Install MechJeb. Gives you all sorts of information in addition to Delta-V.

http://forum.kerbalspaceprogram.com/showthread.php/12384-PART-0-20-Anatid-Robotics-MuMech-MechJeb-Autopilot-v2-0-8

It will show you how much delta V your rocket has when building it and also how much is left in the various stages whilst your rocketing around the universe.

[ProjectXMark1]

You could get MechJeb. MechJeb has a Delta V Stats tab. Here's a thing of you don't like MechJeb.

You may need a calculator, a scientific one. Here's an equation:

Delta V = In(StartMass/EndMass)*SpecificImpulse*AccelerationFromGravity

In( is the natural logarithm. It's included on most scientific calculators as a primary function, I'd say near "log".

What I mean by EndMass is the mass of the stage after ALL fuel has been spent, so for fuel tanks that mean their DRY mass, normal mass for anything that doesn't store fuel/monoprop. Dry mass is in the part info. StartMass is of course the total weight of the ship fully fueled and loaded.

Specific Impulse is the efficiency of engine. Now, I am not entirely sure how to figure out the Isp of multiple engines, it would be beneficial if we all knew. You can find the Isp of the engine in the part info, if the engine is going to be used in vacuum and in atmosphere then do the equation twice using atmosphere for one and the vacuum for the other.

AccelerationFromGravity is Kerbin's surface gravity: 9.81.

I hope I covered your question.

[purpletarget]

One thing to note about doing the calculations is that you have to apply some common sense to it. For example, RCS tanks have a wet and dry mass, but they would not apply into the DeltaV calculation for your main engines...they MAY constitute a slight reserve of DeltaV is you got in a pinch, but mostly they're for maneuvering.

I personally like doing the calculations myself for that reason....knowing where the numbers are coming from provides confidence to my estimates. And then I build large spreadsheets to assist the process, although there are some available around here for download that other people have built.

[Colonel_Panic]

I see this has mostly been answered...

If you're looking to do the math manually, see this page: http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design

MechJeb has already been suggested, but there's another (better) one I might recommend that doesn't come with all the unrelated stuff MJ does, and that's Kerbal Engineer Redux. All it does is offer staging analysis and delta-v calculations, and you can use it only in the VAB or in space depending on your preferences.

So that's the easy way and the hard way. It's just rocket science.