Kerbal X Has More dV in 24.2

[PLAD]

I just noticed that the stock Kerbal X rocket has about 500m/s more dV then it has in 23.5 and earlier versions of KSP. To be precise (according to Mechjeb):

Version........total vacuum dV............total weight on launchpad

22..............6832 m/s......................131.67 tons

23.5...........6818............................131.44

24.2...........7333............................131.24

The differences between 22 and 23.5 are due to the small parts that became weightless (ladders, solar panels) and the addition of monopropellant to the capsule. The huge difference in 24.2 is due to the Mainsail's higher Isp and the lower weight of the Poodle (2.0 versus 2.5 tons earlier).

What does this matter? It means the Kerbal X can now easily do a Mun land-and-return mission! I recall an old challenge where the goal was to land the Kerbal X on Mun with the most fuel still in the tanks, or even try to get back to Kerbin. No one made it back. Recently I've been trying to do a Kerbin-Mun land-Kerbin mission for as little dV as possible and was down to 6863 m/s and decided to give the X a try in 24.2. Piece of cake! Even with the reduced T/W of the X over my test craft I did the mission with 6869m/s and so had plenty of fuel left over. I'd been thinking of another challenge but it would have to be with version 22 or 23.5 and so would not be very inclusive. Maybe a challenge could be done that requires 24.2 and is just to try to have the lowest total dV or the most fuel left over after returning to Kerbin.

Extra note: my take on the theoretical minimums for a Mun landing mission:

75x75km Kerbin orbit to Mun surface pass: 840m/s

Mun pass to landing (in an instant explosion of thrust on the 5500m mountain) : 762m/s

Mun surface to Munar escape: 762m/s

Add in 4350 for Kerbin surface to 75x75 orbit and the mission total is about 6720m/s.

[cantab]

Hmmm. I wonder if Squad will nerf it in .25. AIUI it was deliberately designed to be capable of Mun landing but not return, so it didn't give the player a great ship right away.

[UmbralRaptor]

Looks mostly reasonable (though 4350 m/s to get to LKO would require a *perfect* ascent.)

Mun pass to landing (in an instant explosion of thrust on the 5500m mountain) : 762m/s

Mun surface to Munar escape: 762m/s

Alright, how? I get 798 m/s for munar escape from 5500 m. Maybe knock off another 9-10 m/s including the rotation. But you need ~50 m/s more to get back to Kerbin's atmosphere...

[Kasuha]

It can indeed be done. The lifter stage has even enough dv to circularize now. Pretty hard still, I guess.

Maybe it's better if it is possible as that may make newbies try to improve.

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[PLAD]

4350 to LKO is quite difficult, my best ever was 4349 and I only did it once, generally I can do 4356 reliably with Mechjeb and the right ship. But since I'm assuming everything is perfect for a theoretical minimum I used it.

The 762m/s from sitting on the Mun is the bare minimum to escape Mun's SOI. Your VSOI would be 1m/s, which is, need I say, less than what will get you back to Kerbin directly. But using repeated Munar flybys and small deep space maneuvers you could theoretically build up enough dV to get back to Kerbin. In practice I can make it back to Kerbin's atmosphere from a 5.5x5.5km orbit with a 207m/s thrust, it gives 125m/s at the SOI, then a 16m/s deep space manuever and another Munar flyby gets you home.Since circular V at 5500m is about 563m/s that means 786m/s is already practical.

Enough being mysterious, here's how I did 6869m/s with the 24.2 Kerbal X. This will be my entry in a minimum dV Mun challenge if there is interest:

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[Renegrade]

Kerbol X can definitely return to the surface as is.

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Actually I might have been able to do this with a real proper orbital return, but I wasn't sure so gave my straight up technique a shot.

A brief derp happened when I went to high warp while landed while trying to optimize my return launch position. I forgot the Mun was tidally locked. Derp!

Another brief derp happened when I used imgur for the first time (despite having a two-year-old account) and didn't save descriptions or titles. Titles and descriptions should now be available.

MODS USED:

1. Changed settings in the "Settings" menu of KSP to change resolution to 1900x1000 windowed (based on a custom rez I set up for that purpose), and also set staging to 'tab' instead of 'space'.

That is all.

Edited August 24, 2014 by Renegrade
Added mods used, clarified 'return launch' sentence