Early Career Mode Over Engineering

[Claytsuk]

I think I may have overdone it a little in a fairly early career mode (not unlocked RCS yet) trip to the Mun. Here's the story, what could I do differently to make this easier? Particualry to understand how much DV I need to get there an back again.

Built two ships to go to the Mun apollo style, a lander and tug both with docking ports. Docked in orbit all fine. Some of the tanks were emptied to get me to orbit so sent up a refuller, docked that, transferred fuel, all good. Went to the Mun and got into orbit then send my lander down. First Kerbal on the Mun, great acheivement felt amazing. A little concerned that my tug didnt have much fuel left but was going to use what was left in the loadner to transfer back to the tug after re-docking in orbit to get us home.

Lander Lift off from the Mun went well (~loads of science on board) but no where near enough fuel to re-dock, stuck in a similar orbit. So the situation is tug stuck in mun orbit with a tiny amount of fuel, lander stucking in mun orbit with no fuel, no RCS and 3 kerbals in total stranded. SIGH...

Rescue mission - sent an automated refueller to the mun. Docked with lander and then tug and refuelled and brought them all back home safely.

Now don't get me wrong I'm pleased with the achievement, I'm now an expert at docking my Kerbals are all safe and I got loads of science. But there must be an easier way right?! Probably with one stage to land and come back, probably a lot lighter and uses less fuel. How can I tell if I have aneough DV to make back from somewhere?

[Mat2ch]

Hello Claytsuk,

also if it may be called cheating the KER mod gives you and overview of what dV your stages have. You can use it while constructing your rocket. Then have a look at the Cheat Sheet in the Wiki. It has a dV map posted there. Just add the values you need to get into orbit, transfer orbit, to the moon, etc. and back and from then on it's just plain stupid (that's why some would call it cheating. But NASA did have computers back then. Not as powerful as ours, but they did. And why get stuck in the past? Kerbals are very creative, they have computers! Look at the kOS screen )

[Miravlix]

It's actually my main problem with KSP, real space programs doesn't even drive their car across the parking lot without already having calculated how it would be done.

[Emilio]

You could try having a very light one-stage lander that also servers as your return stage, since the Mum's escape velocity is quite low. When building Apollo-type missions you really have to watch your fuel/dV as maneuvers can be very fuel-intensive, I'm thinking phases like orbital rendez vous.

I wouldn't consider that cheating - Even if NASA didn't have powerful computers early on, all that info was still available, except the calculations had to be done by hand.

Also I should warn that because of the aerodynamic changes in 1.0 the dV charts probably aren't accurate anymore, at least concerning taking off/landing on planets with atmosphere (interplanetary transfers should still be fine).

[TothAval]

as Mat2ch said, use KER or MEchjeb, fly blind and get a feeling or calculate your upper stage mass and build your rocket accordingly. Design, Test, Fail, Redesign and again until you have it, take a look at your ships mass while you do it and try to guess how much units of fuel where missing, or use infinte fuel(if necessary) and maneuver notes if you want to see how much dV was missing.

In my career i created a probe for landings on the mun and, out of frustration, cheated my way back, after several failed attempts, i was tired for that day and went to sleep. but i stuck with the design and improved it the next day, made it lighter, added some fuel and flew very effective(at least i believe i did ) the next time (crossing SOI before the mun, using oberth-effect to raise my apo with 20s burns until i reached mun-soi, liftoff from mun retrograde, reducing kerbinperiapsis with another mun-flyby, and last but not least i increased my apoapsis to be able to reduce my periapsis to reach the athmosphere because i had 7.5 units liquid fuel left and needed to decrease my periapsis 5,x Mkm, i burned to fast and ended with periapsis at 12km, the time bevor that, without raising my apoapsis, i couldn't get to the athmosphere, it went well, opened the chute at 5km, mission succces). i play KSP with some breaks since 2013, having 300h in the game(not that much compared to others^^) and i learned a lot about orbital maneuvering through that, was quite some fun. anyway my construction was able to go to the moon and fly back, cheating was justified

here is a link to the craft-file if you are interested, its 3stage system with a launcher and a small probe https://www.dropbox.com/s/s92cma0kp8wexnt/SP-03%20Gecko%20L.craft?dl=0 the probe can land on the mun and return to kerbin, it has 2xthermometers, 2xbarometers and 2xgoo. no antennas, no science bay. you have to return it to get the science no need to dock with other craft and no capability to do so. have fun

Edited May 1, 2015 by TothAval

[Good_Cat]

Hello Claytsuk,

also if it may be called cheating the KER mod gives you and overview of what dV your stages have. You can use it while constructing your rocket. Then have a look at the Cheat Sheet in the Wiki. It has a dV map posted there. Just add the values you need to get into orbit, transfer orbit, to the moon, etc. and back and from then on it's just plain stupid (that's why some would call it cheating. But NASA did have computers back then. Not as powerful as ours, but they did. And why get stuck in the past? Kerbals are very creative, they have computers! Look at the kOS screen )

KER as Mat2ch suggested is immeasurably helpful.

With the dV per stage, you can build much easier and more effectively. You can effectively build a launch stage to get you into (space)your transfer window or orbit, then your transfer stage to get you there and maybe into an orbit and finally a lander / return stage.

Gives you TWR trust to weight ratio of each stage also very handy after all you might not need t hat big heavy engine you might be able to go for a more fuel efficient one.

KER is a must have.