Help with .24 (or oh, hey now I have to learn math)

[johnnyhandsome]

Ok, one doesn't have to learn math, but I'm finding this to be an interesting challenge.

However, I such at math, so help?

I need to lift 4 tons up to 8,000 meters, moving at between 500-900 meters per second at the 8K meters mark.

How do I figure to build a rocket that'll do that?

Currently I have access only to the LVT 30 and 45, LV 909, Rockmax MArk 55 and the RT-10 and BAAC SRB rocket engines.

I'm NOT looking for a specific rocket design, but rather the math or formula on how to figure this out. The info given in the game doesn't seem to be useful to figuring this out, but what do I know?!

[Alshain]

Typically it's done in terms of Delta V. How much Delta V do you need to move a craft to 8,000 meters. dV incorporates fuel, mass, and thrust.

In stock KSP for example the reccomended dV to get to orbit of Kerbin is around 4500. Note however this is 4500dV in a vacuum, even though Kerbin isn't. So if you use a tool like Kerbal Engineer Redux, you need to have it set to vacuum calculations. It's a tough calculation to do manually.

Here is a cheat sheet. Note however if your using FAR with a sufficiently aerodynamic craft the dV requirements for those planets will be lower.

Edited August 1, 2014 by Alshain

[Red Iron Crown]

Typically it's done in terms of Delta V. How much Delta V do you need to move a craft to 8,000 meters. dV incorporates fuel, mass, and thrust.

Not to nitpick, but delta-V does not incorporate thrust at all. A high thrust ship will have the same dV as a low thrust ship if the wet/dry masses and Isp are the same.

The math to calculate the OP's requirement is non-trivial. Basically, the rocket needs to add enough energy to account for the potential energy of the higher altitude, the kinetic energy of the speed, and the energy lost to fighting gravity and atmospheric drag. Might be easier to just build a rocket and make your trajectory more horizontal in the altitude range you want to get the speed requirement.

[Alshain]

Yes of course, not sure what I was thinking there. It's early... need more coffee. TWR is what you want for thrust. You want TWR to be > 1 to get off the ground.

[-RanZ-]

use mechjeb or kerbal engineer in a sandbox save to figure out everything and then build it back in your career save... much easier than doing maths

[Claw]

There is a recent thread discussing nearly this same topic.

I'll also reference you to my post in that thread. I use a chart I made that tells me the dV required to get to an altitude (shown in this post).

Cheers,

~Claw