Calculating the needed Delta V

[Destroyerofcheez]

Right now Im trying to do the math to make a rocket capable of Launching from Kerbin, orbit the mun, land on the mun, takeoff from the mun, and return with not to much nor to little fuel left over. What I need to figure out is how to find how much Delta V I will need to get there. I know there are Delta V maps, but I have noticed the planets can move around (obviosly) closer or further from each other. Also orbit can come in different shapes, sizes, and angles depending how you burn. These can change the needed Delta V for a burn. What I need is to figure out how much Delta V I will need for a flight, depending on a planets position and its gravity.

[Zombo]

There is a kerbal wiki, and it has all the numbers needed for landing on all the different planets and moons. And other valuable info aswell.

There is also a mod called "Kerbal engineer, redux", this does all the math for you, and gives you a real time readout of your TWR and DeltaV in the VAB and Spacehanger, while building. Plus in flight info while "on mission".

edit: There is also a rule of thumb for transfers in Kerbal. The target "body" should be at your 12 noon position from the location of your maneuver node. And the rendevous point should be at your 9 oclock.

[Proteus]

Yep ...
the formulae for manually calculating dV and other things can be found here:
http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design

As for the needed dV ... these values have to be taken with a grain of salt, as the dV needed can vary by a huge degree, depending on the day of launch (resulting in dofferent planetary consteallations) and the angle of departure (resulting in diferent flying times as well).
Which is why I nowadays prefer to use the launch window planer, which also gives me informations regarding the angle and speed of departure I need to attain when aiming for a certain travel duration and dV use
http://alexmoon.github.io/ksp/

[Walter Sobchak]

Kerbal engineer, redux <--- a must have - it's like having a bunch of math nerds in the room with you

[Destroyerofcheez]

Proteus a écrit :

Yep ...
the formulae for manually calculating dV and other things can be found here:
http://wiki.kerbalspaceprogram.com/wiki/Tutorial:Advanced_Rocket_Design

As for the needed dV ... these values have to be taken with a grain of salt, as the dV needed can vary by a huge degree, depending on the day of launch (resulting in dofferent planetary consteallations) and the angle of departure (resulting in diferent flying times as well).
Which is why I nowadays prefer to use the launch window planer, which also gives me informations regarding the angle and speed of departure I need to attain when aiming for a certain travel duration and dV use
http://alexmoon.github.io/ksp/

Ive already seen this one before but it uses a Delta V map to find how much delta V they need. Also another thing I was trying to do was find how much fuel I would need because of the ship getting lighter when the fuel is used. This only shows how much delta V your ship has. Thanks though.

[Rene]

Destroyerofcheese a écrit :

Ive already seen this one before but it uses a Delta V map to find how much delta V they need.

I don't quite understand. A delta-v-map is just a visual way of representing (in this case) that the delta-v required to get from low Kerbin orbit (say 100 km) to a munar transfer orbit is 860 m/s, then 210 m/s to get captured, and so on.

As an aside for interplanetary travel, the delta-v on the maps indicate the minimum delta-v to get into your typical hohmann transfer orbit to get to that planet. So this always assumes the planets are in the right configuration. If they're off, it will cost you more to get there.

Also another thing I was trying to do was find how much fuel I would need because of the ship getting lighter when the fuel is used.

You're looking for the delta-v. Take a look at this wiki article: http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation.

This only shows how much delta V your ship has. Thanks though.

Which seemed to be what you were looking for.

Edit: Here's more terminology, if you need it: http://wiki.kerbalspaceprogram.com/wiki/Terminology.

[Acus]

All above + this
https://www.youtube.com/watch?v=000zDI2nmq8
and this
https://www.youtube.com/watch?v=QXPhQKkOcYM
and build nice excel sheet which calculate this for you :)