calculating delta-v for take off and landing

[jahkaan]

i have seen the delta-v map for the kerbin system, but i would like to know how to calculate those numbers myself. i would also like to know how to calculate delta-v that compensates for drag. ii have looked for formuulas online, but i havent found any, neither on KSP related sources or real life rocket science sites, so if anyone could explain it to me, it would help me out a lot.

[Decho]

This wiki page goes through calculating the Hohmann transfer delta v requirement: http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design Calculating the delta v required for a launch is fairly tricky, as it also depends on your trajectory (ie. when you begin the gravity turn etc.) but a simple way to do a preliminary estimate is to calculate the delta v for a Hohmann transfer from a 0km altitude orbit up to wherever you wish - which will be fairly accurate on airless bodies. Then you need to account for gravitational and atmospheric drag, which would involve integration and factoring in the flight path. For a landing you could simply calculate the delta requirement for the relevant transfer and then calculate what the orbital velocity at that radius would be and add that much delta v to account for zeroing out landing velocity, which again for an airless body shouldn't be too far off. The requirement is much less if there's an atmosphere involved, to the point where you need hardly any fuel really with the current aerodynamics model.

Edited June 2, 2013 by Decho
slightly misread OP

[Specialist290]

Here are a couple of websites with at least some of the information you'll need:

• Winchell Chung's Atomic Rockets website
  
• Robert Braeunig's Rocket and Space Technology website
  

Both of them contain lots of useful information. Atomic Rockets is more intended to convey the basics across to laymen, while Braeunig's site is for those who are really interested in digging in to all the details. Neither one requires much math (for the final equations) beyond what you might learn in high school. Figuring out how to do specific things in the game is just a manner of knowing the general principles and applying them to your specific situation.

[tomf]

my post here Calculating-interplanetary-delta-v Does a run through calculating the figures for anything without an atmosphere. For bodies with an atmosphere it is much harder.

[tavert]

If you're comfortable reading Python code, there's some good stuff here: https://github.com/numerobis/KSP-scripts

A lot of the equations are explained in comments. Ascent cost can be pretty sensitive to trajectory and TWR, moreso when you're fighting an atmosphere.