New Efficient Lunar Challenge

[Entroper]

I love the new parts! The legs make landing on the Mun a breeze, the engine is nice and lightweight, and the half tank is especially awesome to give your designs that little extra tweak they need to get over the edge.

So I built a ship that will land on the Mun and return, using only 7 1/2 LFTs for fuel. I didn\'t take video of this attempt, as several of my other designs failed and I was tired of deleting gigabytes of failed video. > But I\'ve attached the craft, and I\'ll take some video of the journey next time. It\'s quite close to the margin, and I think adding one more half tank to the middle stage would make the mission much easier, but I promise it\'s doable as is.

Can anyone do it with only 7 tanks? 8)

[MafiaMoe]

5.5 and got into a poor orbit around the Mun. Not enough fuel left to land...

I think either 6.5 or 7 is do-able.

[Entroper]

I just landed with 6. I can get back, but I\'ll only crashland, as I don\'t have a chute or a decoupler. I think you can make the one-way trip with 5.5 tanks.

[Kosmo-not]

I landed and returned safely with 6.5 tanks. This included Mun orbit insertion prior to landing.

[Entroper]

I did the one-way trip on 5 tanks. I was even able to return to Kerbin, just not safely. Ship attached.

EDIT: It\'s mildly unstable because of the lander legs. There\'s plenty of fuel to swap out the 3 legs for 4 legs, I would think. You\'ll probably save that much fuel by flying straighter during the ascent phase.

[Kosmo-not]

Well, I\'ve outdone myself already. Got there and back home safe on 5 tanks. There was a sliver of fuel left after landing back on Kerbin.

[JellyCubes]

Landed on the Mun and returned safely* with 3.5 tanks. ^{*Landed on a hill so constant control imput is required to prevent toppling over and save-scummed once because time warp did not unwarp quickly enough.}

No landing legs, no RCS, no SAS and no parachute.

[Kosmo-not]

Landed on the Mun and returned safely* with 3.5 tanks. ^{*Landed on a hill so constant control imput is required to prevent toppling over and save-scummed once because time warp did not unwarp quickly enough.}

No landing legs, no RCS, no SAS and no parachute.

How much fuel was left after that?

Do you think that is the absolute minimum to accomplish a Mun mission?

[boolybooly]

Kudos to Jellycubes, that looks like the minimum.

I tried 3 tanks in various configs but could never get back, the extra half tank would have done it no problem.

[Kosmo-not]

Yes, good job there, JellyCubes.

I couldn\'t get there and back with 3 tanks (I don\'t know if I just need to adjust my ascent trajectory). However, I can offer an improved 3.5 tank design. This will give you a little more fuel to spare.

[JellyCubes]

I had around 40 units of fuel left at the end.

3.5 tanks is probably reaching the limit for Mun landings. 3 tanks might be possible everything would have to be done perfectly. May be a flight computer module could do it.

[Entroper]

I had around 40 units of fuel left at the end.

3.5 tanks is probably reaching the limit for Mun landings. 3 tanks might be possible everything would have to be done perfectly. May be a flight computer module could do it.

I tried 3 tanks just now, and on my way back, I got the periapsis to Kerbin down to 345 000 m. So close. Of course, you still need more to cushion your actual landing. But I bet you\'re right, you could do it on a perfect run.

[Entroper]

Two and one half tanks to the Mun.

No prayer of getting back home, of course (or even off the surface again for that matter). 8)

The margin on this mission was incredibly tight. You have to manage throttle during takeoff, to reduce air resistance. You have to make your trans-lunar insertion burn at LKO, around 75 km, to take advantage of the Oberth effect (no warping around at 50x time and 150k altitude). And you have VERY little budget for landing fuel. Hence, I tipped over because I couldn\'t find a flat spot to land.

[Awaras]

Two and one half tanks to the Mun.

No prayer of getting back home, of course (or even off the surface again for that matter). 8)

The margin on this mission was incredibly tight. You have to manage throttle during takeoff, to reduce air resistance. You have to make your trans-lunar insertion burn at LKO, around 75 km, to take advantage of the Oberth effect (no warping around at 50x time and 150k altitude). And you have VERY little budget for landing fuel. Hence, I tipped over because I couldn\'t find a flat spot to land.

I tried your ship and managed to crash into the mun at 80m/s...

[Entroper]

I tried your ship and managed to crash into the mun at 80m/s...

That was what happened on my first attempt.

To save a little bit of fuel, you should do a correction burn the very instant you are captured by the Mun\'s SoI. Put your periapsis at about 1 000 m, then coast to that point, then burn off most of your horizontal speed (again, using Oberth here, burn fuel at low altitudes whenever possible). Then you WAIT until you\'re about 100 m above the surface, holding your breath and crossing your fingers, before relighting the engine for landing. I had literally less than 10 seconds of fuel left for landing, and not at full throttle.

[Entroper]

Third attempt didn\'t go as smoothly, but still landed with no dead Kerbals:

I made two mistakes: I didn\'t tip over soon enough/quickly enough, so my initial apoapsis was much higher than intended. I somewhat compensated for this by not completely circularizing, even putting my periapsis in the atmosphere since I knew I wasn\'t going to reach it anyway before trans-munar injection. And the second mistake is pretty obvious, I hit the throttle too hard when landing, wasted a bit of fuel going back up, and ended up running out on the next pass and crashing a bit. So you can see it\'s clearly possible to do with a bit more skill than I displayed.

[pina_coladas]

This thread makes me wonder what our real life apollo era would have looked like if we were only sending an empty command pod with three crash test dummies up there...

[Kosmo-not]

Has the mission changed from going to the Mun and back to just going to the Mun?

[Entroper]

Has the mission changed from going to the Mun and back to just going to the Mun?

Either or both, at this point.