Micro Kerth return module

[lawsonuw]

After experimenting with rcs thrusters. I decided to find the smallest craft that would return safely from the Munar surface. I\'ve estimated that each thruster provides 2.18 thrust. (or enough thrust to lift 0.22 Mu on Kerth) So, at Munar surface gravity two thrusters should be enough to lift the command module, parachute, and one RCS tank. Still, the thrust to weight would be marginal. I\'ve tried 3 and 4 RCS thrusters so far. Both are able to reach Munar orbit with a bit over 1/3 of a tank left. And assuming you got the orbital inclination right, can complete the return trip with some fuel to spare. (About 1/6th of a tank is needed to reach Munar escape velocity retrograde to Munar orbit. The final 1/6 of a tank is then more than enough to setup an aerobraking return trajectory. )

If you had a Kerbal Mun landing, like in these two screen shots, it\'s easy to recover with this return module. Use SAS and RCS to tip the ship on it\'s head pointing (mostly) strait down, and kick in full reverse RCS. Once +10m/s vertical velocity is reached, start rolling over allong 90 or 270 degrees longitude on the nav ball while controlling latitude to keep the vertical velocity at +10m/s, then keep thrusting till orbit is reached. (sorry no take off screenshots, I\'m kinda busy right then )

Landing back on Kerth is easy, just pop the chute and watch the (survivable) fireworks. The empty RCS tank and thrusters are light enough that you only fall ~11.5m/s this is slow enough that the expolsion of the RCS tank slows the command module enough to survive. Or if you have some fuel you can thrust before landing to drop the impact speed to just over 10m/s and make the landing gentler for the Kerbonauts. (still plenty of fireworks though.)

Lawson

[sal_vager]

I just tested this myself yesterday, to see if an \'8 tanks to the Mun, 1 RCS return\' was possible.

Like you say, 2 thrusters wasn\'t enough, I could barely get off the delivery ship let alone get into Munar orbit , I can\'t remember my fuel levels during the flight but yours sound right.

Any idea what the ideal number of thrusters would be?

Edit: I successfully returned to Kerbin from the surface of the Mun and landed in the sea with just 1 RCS tank and 4 thrusters (+ chute and capsule of course)

[Alchemist]

1 RCS tank is barely enough for perfect trajectory. Too big chance to get into orbit with a bit too high periapsis.

I prefer 2 tanks + 8 blocks. But once this go to reentry trajectory with 1 tank full.

[lawsonuw]

I\'ve made a full Munar lander with 3-4 tanks 3 wings and 8-10 RCS blocks. That\'s enough to touch down from ~50Km and -100m/s and return to Kerth. No ASAS so landing is tough, the analog sticks on my controller help a lot.

Lawson