Rocketry: Luna return missions

Overview

This guide will show you how to get to Luna and return!

Introduction: Rocketry parameters and general dV info

(There is a guide on rocket parameters)
dV (in m/s usually) is an astrodynamic parameter that describes the effort necessary to preform orbital maneuvers, such as orbiting a planet or transfer to a moon
TWR is the thrust to weight ratio, if a rocket’s stage has a TWR of 1 or greater, your rocket will lift
To orbit Droo you need around 4700m/s dV
To transfer to Luna you need around 2300m/s
For Luna orbit you need around 800m/s
For Luna landing and Droo return you need around 2000m/s
Total of around 10000m/s

Rocket design

Firstly you need to plan out your rocket in your head, it doesn’t need to be a perfect calculation of everything necessary for Luna, but it helps you know what stage does what, for example:
1st stage nearly gets you into Droo orbit,
2nd stage finishes the orbit and burns half way to Luna,
3rd stage finishes the burn to Luna and captures you into Luna orbit,
4th stage lands on Luna and has enough power to put you back into Luna orbit,
5th stage returns you to Droo
You want to make sure that your rocket has at least 10km/s dV (you can see this in staging or when you analyse performance of an engine
I made mine with
Stage 5: ~1492m/s using Liquid engine, cycle: electric, nozzle: Bell (length 80%)
Stage 4: ~1875m/s using Liquid engine, cycle: gas generator 1, nozzle:Bravo
Stage 3 ~2649m/s using Liquid engine, cycle: gas generator 1, nozzle: Bravo
Stage 2: ~1905m/s using Liquid engine, cycle: gas generator 2, nozzle: Bravo
Stage 1: ~3766m/s using 7x Liquid engine, cycle: Full flow staged, nozzle: Aerospike (length 0%)
Longer nozzles are more efficient in vacuum, shorter are more efficient in air
Make sure the TWR of the specific stage is greater than 1, this specific rocket description is what I made, so as long as you follow the dV required for each stage it doesn’t matter if you made yours like I made mine
(Tip: quicksave frequently)

Transfers and orbital tips

To transfer to Luna you can use this simple trick:
(assuming your orbit is almost circular) When you target Luna, in rocket view when the target arrow (blue) aligns with the prograde arrow (green) or you lock to target and once your rocket is parallel to the surface of Droo you are at the transfer window and you can burn to Luna
When returning from the moon you can use this trick: when in orbit you can burn against the orbit of the moon to slow down to Droo
The inner burn (craft’s place shown in photo) decreases your orbit around Droo once you escape Luna’s SOI (Sphere of influence)
the outer burn increases your orbit around Droo once you escape Luna’s SOI