Rocket Delta V Equation

[Gaarst]

I was planning a landing on Eve but couldn't figure out how I could know how much delta v my rocket could provide for take off without using mods.

So I made a few equations to calculate delta v, based on the ideal rocket equation for delta v and basic physics, in vacuum and inertia​:

For a single stage rocket:

Constant Thrust:

ÃŽâ€v = 0.2 * F * ln(n / (200 * m_f) + 1) / C

Variable Thrust:

ÃŽâ€v = 9.80665 * I_sp * ln(n / (200 * m_f) + 1)

For a multiple stage rocket:

Constant Thrust:

ÃŽâ€v = 0.2 * Σ_s (F_s * ln(m_s / (200 * m_f,s) + 1) / C_s)

Variable Thrust:

ÃŽâ€v = 9.80665 * Σ_s (I_sp,s * ln(m_s / (200 * m_f,s) + 1))

Where :

F is the thrust (needs to be constant) in N

C is the fuel consumption (needs to be constant) in l/s

n is the initial fuel quantity of the stage in KSP fuel units

m_f is the mass of the rocket when all fuel of the stage is consumed in t

I_sp is the average specific impulse in vacuum of the stage in s

Subscript s means "at stage s" (change stage whenever an engine or a part is decoupled)

For a single stage rocket with: Command Pod Mk1 + FL-T400 + LV-909, it gave me a delta v of 3169.4 m/s

Does anyone know if these equations are right or can check them ingame vanilla or with a mod ?

Thank you for helping,

Gaarst

[Th3F3aR]

http://forum.kerbalspaceprogram.com/threads/95693-delta-v-to-space-im-getting-crazy

Asked kind of the same question there, check out if thats what you need

[Red Iron Crown]

Constant or variable thrust is not relevant in calculating delta-V. Just use the Isp of the engine in the conventional rocket equation:

dV= Isp * G₀ * ln (m_wet/m_dry)

(note that KSP uses 9.82 for G₀)

For a rocket with a Mk1 pod, FL-T400 and LV909 this yields 3119m/s in vacuum.