To the Mun, Part 1

[rabidchild]

Noob question.  Remember how nice and patient you guys are with noob questions?  haha

 

I have played To the Mun, Part 1 Training tutorial many times now.  Not because I can't achieve a circular orbit, but because I cannot achieve the optional objective of landing on Mun.  No matter how I plan my approach, I usually only have about a 1/4th of a tank of fuel by the time I have done all the necessary maneuvers to achieve circular orbit.  My orbital velocity is around 500 m/s.  A fourth of a tank of fuel is not even close to enough to slow down the ship to a complete stop that will allow me to free fall to the surface.  I am trying to be as conservative with the fuel as possible, but it doesn't look like the training mission even gives you close to the amount of fuel that you need to land the craft.  Please help in a noob friendly way.

 

Thank you all!

[Reactordrone]

If you use the main engines to do the manoeuvres you won't have enough fuel to land, you'll only have enough to get into Munar orbit and return to Kerbin. It is possible to land and get back into Mun orbit in that training scenario but only if you use the massive amount of monopropellant to do a lot of the orbital manoeuvres.

 

 

ETA- If you are going to fly with the RCS you'll need to fly sideways since there are only linear RCS ports and none are facing backwards.

And just to add some figures, if you use all of the mono up first you'll get about 384m/s out of it and then have 2055m/s delta v available from the liquid fuel/oxidizer, just enough to fly to the Mun achieve an orbit, land and return to orbit.

Edited December 16, 2015 by Reactordrone

[Scarecrow]

Also to add that coming to a stop and then free-falling to the surface is a very inefficient way of landing on the Mun, as you will need to use fuel to fight gravity and stop you going to fast as you fall.  A more efficient way is to do a relatively small retrograde burn from orbit so that your periapsis is only a few thousand metres, and then burn retrograde to slow down when you get closer to the surface, the idea being that when you have almost come to a stop, you are only a few metres up.

[katateochi]

From a ~50km orbit you need about 750m/s dV to land (you can do it with quite a bit less, but that give you good overhead for inefficient descent or adjusting landing position). 

I was going to say what @Scarecrowsaid about free-falling being inefficient, you only want to completely kill all horizontal velocity just before touch down.  

The other way to land on Mun is perhaps a bit more thrilling but if done right is the most fuel efficient way (if done wrong, no part of your craft will survive!).  When you are on the opposite side of Mun to where you want to land burn retrograde to lower your Ap to about 8km (just make sure you're not coming in over mountains).  Then turn yourself to face prograde and timewarp round until you are getting close to your Pe marker (the reason for turning prograde while still on the other side is that now you'll be facing almost retrograde so no panic to re-align yourself, that's optional though).  As you reach your Pe make sure you're right on the retrograde marker (which will have you aligned almost horizontally) and slam your engines on full.  Bring your speed down to a couple hundred m/s and ease off into a more gradual powered descent. (You could do a bit of freefall here without gaining too much vertical speed).  
The lower you can perform the hard burn the more efficient it is, but equally the more likely you are to smash into a mountain or fail to slow down in time.  It's not called a suicide burn for nothing!  Start practicing it with you Pe at 10km and gradually lower that as you get better.  If your craft has enough TWR then lowering it right down to 3-5km above the ground is doable, but you make have to take evasive actions around hills so then it loses it's efficiency.  

 

 

[rabidchild]

Thank you all for your replies. One question. What keyboard key do I press to use the monopropellant?  Is that the same thing as the asdw that you use to pitch and yaw your craft?  Thank you. 

[Reactordrone]

13 minutes ago, rabidchild said:

Thank you all for your replies. One question. What keyboard key do I press to use the monopropellant?  Is that the same thing as the asdw that you use to pitch and yaw your craft?  Thank you. 

You'll need to turn it on with the R key and to fly sideways you'll need to use the translation keys IJKL with H&N for forwards/backwards. Align your ship to a normal/anti-normal direction, rotate your ship until you get an RCS port facing backwards and one of the IJKL keys will provide forward thrust (it will take a while to burn through three tonnes of monopropellant).

That training scenario isn't designed to let you land but it's an interesting challenge to work around the limitations. Pity you can't EVA in that scenario or you could try to return to Kerbin using the EVA packs.

Edited December 16, 2015 by Reactordrone

[Vanamonde]

How about trying it with a different guide and example rocket?

[Kerbol Macrosystems]

1 hour ago, Reactordrone said:

normal/anti-normal direction

That's the direction towards or away from the Mun/planet in case you haven't learned orbital mechanics-speak yet.

[Reactordrone]

51 minutes ago, Kerbol Macrosystems said:

That's the direction towards or away from the Mun/planet in case you haven't learned orbital mechanics-speak yet.

That would be radial/ anti-radial. Normal and anti-normal are aligned north/south when in an equatorial orbit ( the purple ones ).

[rabidchild]

Wow!  These forums are awesome!  Thank you for helping me surmount the learning wall.  This noob feels very welcome and valued.  

[Sirine]

There are old times challenge that a few version back.

I've not try that on 1.0.5. But I believe it can be done. Op out the land back on Kerbin part.