Challenge Lunar tight dv challenge

[DeadlyCZ]

Greetings fellow Orbinauts,

this might seem as an easy challenge, but the completition isn't the only thing that matters here.

You are starting at CSSC in XR-2 mounted to HCLV. Your goal is to get to LEO, perform a TLI, land softly at Brighton Beach, take off and return to any base of your choice back on earth. Seems pretty easy, doesn't it?

Here is the trick. You have to use the expert settings on XR-2 and no refuelling is allowed (although you have the 2 tanks in payload bay). You also have to carry the CHM for the whole trip. And finally, you have to abandon the HCLV once you get to orbit (the HCLV must reentry again, we don't want any garbage in space, right? ), so the final LEO insertion has to be done with XR2 itself. I don't have any experience with LUA scripts, so we will have to rely on honesty.

I managed to do it on my first try, although it was really close (as you can see, I burned through all of my main fuel, most of rcs fuel and my coolant almost overheated during reentry... yes, I did some fatal mistakes)

Scenario file included in attachments, XR2 config file here: http://pastebin.com/Yvn6XmSc

 

[blixel]

You need to provide an xrcfg that defines the exact limitations of the XR2. The XR2-EXPERT.xrcfg that I have uses the following:

• MainFuelISP=0
• LOXLoadout=0
• APUFuelBurnRate=5
• RequirePayloadBayFuelTanks=2

With that configuration, I have a maximum ΔV of 7,252.59 m/s. (I can get slightly more if I cut the LOX and APU.) Your scenario has 3 crew members, so I can cut the LOX down to just 55.5kg and still have enough time to get to the moon and back. That will give me another 34.5 m/s. If I jettison the external tanks after use, I'll gain another ~127 m/s.

But to make a trip to the moon and back (starting from LEO), I need about 8,585 m/s worth of ΔV.

• TLi burn = ~3150
• LOi burn = ~850 (could be as low as maybe 825 m/s)
• Lower PeA to 1km = ~4.5 m/s
• Braking burn = ~1680 m/s
• Hover & Land = ~300 m/s (165 m/s absolute minimum with a near *perfect* landing - e.g. no time wasted hovering.)
• Launch back into Lunar Orbit = ~1750
• TEi burn = ~850

So without even leaving the ground, I know I don't have enough fuel for the flight. I'm guessing that your EXPERT configuration does not have RequirePayloadBayFuelTanks=2?

If I toggle that option to the default value, RequirePayloadBayFuelTanks=0, then I have 9,735.62 m/s. That gives me plenty of fuel to make the flight with over 1,100 m/s to spare.

So in order to try this challenge, I need to know what EXPERT settings to use.

Thanks.

 

[DeadlyCZ]

I posted the config file on pastebin (it's in the first post) - totally forgot about this option...yes, it's on 0...

It is pretty easy for majority just to complete it, but can you complete it with lowest dv possible? I messed up my lunar landing (wasted over 1km/s dV hovering and retro braking), so I'm glad I even made it back