How to land on mun and get back to kerbin?

[Zerodaspace]

I have sucessfully landed on the moon with a 1 man capsule but i always dont have enough fuel to get back to kerbin

[Cal'Mihe]

MOAR BOOSTERS!

Sorry, it had to be said

Either you'd bring more fuel, cut down on the weight of your mun-craft to make the fuel last longer, or use a more efficient engine (if you are not already doing that)

Depending on how efficient you are with your burns and ascent profile, it might also be that you can optimize your fuel use with the existing craft somewhat.

But seriously, try adding more boosters in the initial stage and use them instead of the liquid engines to get up into the lower atmosphere

[Crush]

When you want a really elegant mun mission, learn docking and do an apollo-style mission with a detachable lander. That way you can keep the fuel for the return trip in mun orbit, so you don't need to land it and bring it back up.

...or just add more stages below your existing rocket. There is no problem which can not be solved by adding more parts (except for having too many parts, of course).

When you want better advise, you could post a screenshot and the .craft file of your rocket. That way we could suggest improvements.

Edited July 16, 2013 by Crush

[allmappedout]

Both good ideas, however, I think the best method is to plan how much fuel you actually need to take with you.

I'm not sure if you're familiar with the concept of Delta V, but this represents the amount of change in velocity you can do (ie: how much you can slow down or speed up) over the course of your mission.

https://en.wikipedia.org/wiki/Delta-v

This explains the theory, but a simpler explanation is that for any given engine, and any given amount of fuel, it can push a given mass from one speed to another speed.

Calculating Delta-V manually for a multi-stage rocket is fairly tedious, so I would recommend either Kerbal Engineer or Mechjeb to output the calculations for you. In terms of actually getting to the Mun and back, the numbers you require are as follows:

~4000-4500m/s dV - to Kerbin Orbit (speed up)

~850m/s dV - Kerbin to Mun escape velocity (speed up)

~250m/s dV - Mun orbital capture (slow down)

~500-700m/s dV - Mun landing (slow down) *this stage is the one you want the most leeway on, as it's very dependant on how efficient your landing is*

~500m/s dV - Mun take-off to Orbit (speed up)

~250m/s dV - Mun escape velocity (speed up)

Rough Total: 6550m/s dV

+10% leeway = 7205m/s

Bear in mind that as your craft gets smaller, the mass also shrinks, and so you need less thrust to push the craft, so you can use more efficient engines (hint: look at an engine's Isp (specific impulse) as well as its thrust. The Isp is a measure of how efficiently an engine burns fuel. In space you don't need high thrust, you need high efficiency, so look at the small engines and nuclear engines, for example).

If you use a maneuver node well for the escape velocity you can use an 'aerobrake' maneuver which means that Kerbin's atmosphere will slow you down (ie: you have a Periapsis under, say, 40km), so you don't need to spend any more fuel. Otherwise, in theory, you would need to use another wedge of dV to slow down one on a munar escape orbit to get yourself into a stable Kerbin orbit which you can then de-orbit from.

I hope this helps! All those figures are rough estimates based on my memory and vague estimates, but I hope it explains the idea of building a rocket for a purpose, rather than just winging it (Although winging it is the Kerbal way!).

Edited July 16, 2013 by allmappedout

[capi3101]

It may be that you're using too much fuel for landing. Can you talk us through how you perform a landing sequence typically?

I find that with the basic little Scott Manley Minmus rocket lander (i.e. a 4 tonne module consisting of a Mk1 Command Pod with one chute, a stack decoupler, an FL-T400 tank, LV-909 engine, four lander legs and a ladder), you'll make it back to Kerbin without problems if you've got ninety units of fuel left in the tank when you're done. Eighty is bingo fuel - hit the deck or hit space. You can make it back on 75 but you're going to have to use good piloting. Seventy or less and you might as well land, because you're definitely not making it back. If you're still not used to Mun landings, begin killing your horizontal velocity about 8000 - 5500 if you're more experienced. Once your vertical, kill your burn, switch to IVA, watch your radar altimeter and do not fire up that engine again until you're down to 1000m above the deck (incidentally, the radar altimeter can give you an idea of where the deck is, and let you estimate how far you still have to go). Then it's just a matter of watching what you're doing. Note that this is not the most efficient method fuelwise, but if you're not an expert in Mun landings this oughta give you enough play to make it to the surface with between 80-90 units of fuel remaining.

[sumghai]

One way I got around the limitations of the "direct ascent" method was to instead go for a Kerbin Orbit Rendezvous (KOR), as per my first and successful Munshot.

In short:

- Design a lander to have just enough fuel to land on the Mun and launch itself into a stable orbit around the Mun

- Launch the lander with no crew into Kerbin orbit

- Design a Crew Return Vehicle (CRV) and a Munar Transfer stage with enough fuel to push both the CRV and the Lander to the Mun

- Launch the CRV and transfer stage into Kerbin orbit

- Dock the Lander to the CRV/transfer stage combo

- Transfer to the Mun

- Move crew from the CRV to the lander (Kerbal Crew Manifest mod)

- Land the lander

- AfterMunar EVA, fly the lander back up to meet the CRV

- Transfer the crew back to the CRV

- Use CRV to get back to Kerbin

- ????

- PROFIT

[Cashen]

EDIT: Nevermind, was responding to the wrong person.

Edited July 17, 2013 by Cashen

[SRV Ron]

MK59D Moon Visitor is a lander available from this forum that can easily land and return from Mun with fuel to spare. With a good launch and efficient Mun encounter, you will have enough fuel left in the second stage for landing, but, stage before actually landing since it doesn't have the legs, and use your lander for the last thousand meters. Use the internal radar altimeter or visual shadows as the actual surface is much higher then what the barometric altimeter says it is. If you don't waste too much fuel on the landing itself, there will be plenty left for return. Burn long enough to orbit Mun or, if facing Kerbal, hit escape velocity. Then set up a maneuver that gets you a paragee of 15,000 meters and let aerobraking bring your Kerbals home.

[Vanamonde]

MK59D Moon Visitor is a lander available from this forum

Thanks for shilling for me! Here's the thread: http://forum.kerbalspaceprogram.com/showthread.php/25029-A-moon-rocket-for-newbies

[cpt_nosh]

You can't go to Mun and back... that's a myth.