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Delta V calculation


Sriram
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Hi, I am beginner to the game. I am facing difficulty in calculating the  propellant required mass and  delta v for reaching the particular height. 

Height to be reached: 200km

So, please help me .

 

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Welcome to the forums! :)

Your confusion is understandable, this is a very difficult problem to solve because it has far more variables than just dV. It depends on your thrust as well, and on the shape of each individual rocket. See the more detailed post I made in this thread.

My recommendation here is not to bother with math at all. Instead, build the payload you need lifted that high, then stick a rocket stage under it, and go launch. See how high it gets. If not high enough: add more power and more fuel.

If, however, you want to go into orbit at a 200 km altitude over Kerbin's surface, and not just fly straight up... that amount of dV can indeed be calculated.

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KSP is set up as a game to experiment by trial and error. 
And, the detailed math is awkward.  But there are approximations you can do with secondary-school physics, if you want.

If you are willing to accept (from some physics course) that the projectile height follows   h = v×t − 0.5×g×t²   as a function of time t after being thrown up at velocity v and then pulled down by gravity with acceleration g, then you can complete the square  h = −0.5×g×(t − v/g)² + 0.5×v²/g  and see that the peak height is 0.5×v²/g.   So to reach h=200km you might expect to need an initial velocity v = sqrt(2×h×g) = sqrt(2 × 200'000m × 9.8m/s²) = 1980m/s.   KSP since version 1.6 will estimate the delta-V of a rocket, so you might add fuel until it says 1980m/s, or maybe round 2000m/s, and see if that gets you close.

There are several bad assumptions behind that approximation, but If you want to calculate, I would start with that approximation, and then maybe estimate corrections for the effects outlined in the post that @Streetwind linked to above. 

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