Fuel Bug Abuse Munar Landing

[Bluejayek]

The fuel bug! So many challenges now require full throttle to avoid this bug, but where are the challenges taking advantage of it! It is a glorious opportunity!

Hence, I present you the Fuel Bug Munar Lander Challenge!

The challenge is simple. Launch the smallest single stage craft possible to land on the Mun, while abusing the fuel bug as much as you desire.

Entries will be ranked on weight on takeoff, and for tiebreakers, fuel remaining after landing (So take a screenshot of this!)

To enter, please provide:

Screenshot on the launchpad.

Screenshot in Kerbin orbit with the fuel remaining displayed.

Screenshot on the lunar surface with fuel remaining displayed.

Evne though I didn't take all the required screenshots, I'll kick this off with my entry, coming in at 10.5 tons on the launchpad, with something like 80kg of fuel remaining.

Leaderboard:

1) Soralin, 2.3 tons, 1.4L of fuel remaining.

2) wired2thenet 20.4 tons, 0 fuel remaining. It all blew up on landing.

3)

Modded Leaderboard:

1) wired2thenet 2.4tons, 92.1L of fuel remaining.

2)

3)

PS: For those of you who do not yet know, the fuel bug is this. Thrust scales linearly with throttle, while fuel consumption scales quadratically. For example, at 25% throttle I get 25% of the thrust, but use 6.25% fuel. At 1% throttle I get 1% thrust, but use 1/100th of a % of the fuel.

Edited August 30, 2012 by Bluejayek
Oops.

[Shadownailshot]

I am so gonna do this. I have to ask.... Why the big engine on the tiny little sucker?

[maltesh]

Big engines have more thrust, so you can fly them with a lot less throttle, allowing you to abuse the fuel bug more effectively.

[Shadownailshot]

Hm. I would have assumed that the aerospike took the most advantage of it, having the highest ISP and a rather low mass.

[ggPeti]

But can you efficiently lift off with it on the lowest possible trust? That is the question.

@OP: 25% trust means not 12.5, but 6.125% fuel consumption.

[Bluejayek]

But can you efficiently lift off with it on the lowest possible trust? That is the question.

@OP: 25% trust means not 12.5, but 6.125% fuel consumption.

You can't lift off at the lowest possible thrust, but you can do so at around 10-15%, which is already very efficienct. Further, you can do an effective TMI burn at about 1% thrust (or however low the lowest possible is), which uses aproximately 0 fuel. Finally, you can land on the mun at very, very close to the minimum possible throttle, so the landing takes tiny amounts of fuel.

[Soralin]

This is about as minimal as it gets.

command capsule - 0.8

1 half size small fuel tank - 1.125

1 areospike engine - 1

Total mass = 2.925

And over 88L, nearly half the fuel tank left over. I probably could have made it back to Kerbal even. (At least with some landing gear added perhaps, I blew up when I tried as is)

[Bluejayek]

Nice rocket Soralin. I just have one small question. How on earth did you launch that? Rockets tend not to be stable sitting on an aerospike

Is there one of those new launchpad detachers that your not showing? (Not a problem, just wondering)

[wired2thenet]

20.4 tons Launchpad;

Somewhere around 450L of fuel left upon crashi....er, landing. Unfortunately, I botched the landing too many times to count, the last attempt nearly fatally, and it destroyed the fuel tank before I could get the finally tally. The screenshot attached shows the last known quantity about 3-5 minutes before impact. Took video of the whole process along the way though, but it's still rendering. The entire trip took about 35 minutes or so.

Going to have to try this again with a smaller craft after I've had a few more cups of coffee.

(and no, the mechjeb was only used for Kill Rotation, Pro/Retro-grade maneuvering, and the orbital information).

[Soralin]

Nice rocket Soralin. I just have one small question. How on earth did you launch that? Rockets tend not to be stable sitting on an aerospike

Is there one of those new launchpad detachers that your not showing? (Not a problem, just wondering)

Nope, I just launched it quickly before it had time to tip over. And actually, testing it again now, with just those 2 parts it seems unusually stable on the launch pad, it doesn't budge at all when I try tipping it, and it's not heavy enough to do any damage to it by just sitting on it.

Edited August 30, 2012 by Soralin

[Bluejayek]

It would seem that it would be in unstable equilibrium on the pad since it is symetric. Kind of like how you can balance a bar pendulum pointed upwards, but any force will move it. So, as you say, it probably will sit there until something pushes it.

Nice craft wired, but you can go smaller

I really don't think you need that full double size tank, try with half that.

[wired2thenet]

Hehe yeah. I suck at managing fuel levels, so I wanted to start with some wiggle room lol.

Soralin's is as small as you can get using stock parts, from what I can tell. Thing flies VERY easily too. I'm impressed.

With some of the modded parts (the non-cheat parts), you can get down to about 2.4 tons.

[Shadownailshot]

This is about as minimal as it gets.

command capsule - 0.8

1 half size small fuel tank - 1.125

1 areospike engine - 1

Total mass = 2.925

And over 88L, nearly half the fuel tank left over. I probably could have made it back to Kerbal even. (At least with some landing gear added perhaps, I blew up when I tried as is)

I was gonna do the same thing with lander legs... damn.

[Bluejayek]

I was gonna do the same thing with lander legs... damn.

Then go ahead and try to beat his fuel level Or, use those legs, and return!

Most amusing in regards to this was when I had a slightly larger craft, over in the "smallest craft with the largerocket parts" thread. I was launching off the moon on a return trajectory, and had around 450L of fuel remaining. "Great!" I thought. "Plenty of fuel left. I'll just speed things up by doing a quick full thrust burn". I did that quick full thrust burn, and used 400L of fuel in just a couple seconds, when I had previously been burning more on the likes of 1L/minute of fuel. A clear indication of how rediculously efficient engines get with the fuel bug.

Edited August 30, 2012 by Bluejayek

[wired2thenet]

Parts: Small LF Engine, Mechanical Mouse Industry Capsule, Aerospike.

Total weight in VAB: 2.375

Total weight on Pad: 2.4

Fuel left: 92.1L

I admit on this one I botched the landing twice again (landing on that spike is a pain in the butt!). The third attempt I gave up and let MechJeb land the last 50m. Still fell over, but I managed to right myself at the last moment.

Next time I want to try it with Chickenplucker's Tumblebot

Edit: YouTube video of the entire trip (sped up)

http://www.youtube.com/watch?v=ce_vVHeF4Mw

Edit 2: No spoiler tags? Or did I miss it somewhere? Will edit again when I find it EDIT3: Fixed ... sorry about that!

Edited August 30, 2012 by wired2thenet

[Soralin]

Hehe yeah. I suck at managing fuel levels, so I wanted to start with some wiggle room lol.

Soralin's is as small as you can get using stock parts, from what I can tell. Thing flies VERY easily too. I'm impressed.

With some of the modded parts (the non-cheat parts), you can get down to about 2.4 tons.

I thought it was as small as you could go too with stock parts, and then I realized, there are some other less commonly used stock parts.

The Mk2 to size 1 adapter masses 0.5t, and comes with 75L of fuel. With the reduced mass, and the fuel bug (and both together, allowing me to thrust even slower), that's just enough to land on the Mun, with 1.4L left to spare.

Command pod Mk1 - 0.8t

Mk2 to size 1 Adapter - 0.5t

Toroidal Aerospike Rocket - 1t

Total mass: 2.3t, Fuel left - 1.4L

Edited August 30, 2012 by Soralin

[wired2thenet]

Crap, forgot about that adapter!

[AncientAstronaut]

I already downloaded the specific impulse fix so I can't do this challenge. Sounds fun but I'd rather have a fixed bug than a cool one to take advantage of.

[Soralin]

I already downloaded the specific impulse fix so I can't do this challenge. Sounds fun but I'd rather have a fixed bug than a cool one to take advantage of.

You could always install a fresh version of 0.16 to a different folder if you wanted to do it.

[Accelerando]

I don't get what some of you say about aerospike instability on the launch pad. I've had 12m tall rockets sitting on nothing but an aerospike and they never budged as long as I didn't touch the maneuvering controls.

[Shadownailshot]

I don't get what some of you say about aerospike instability on the launch pad. I've had 12m tall rockets sitting on nothing but an aerospike and they never budged as long as I didn't touch the maneuvering controls.

That's what they're talking about.

[wired2thenet]

Total mass: 2.3t, Fuel left - 1.4L

Been trying to beat your fuel level with the same ship . I know I made some very bad mistakes early on the launch into orbit (and jeez, chasing the Apoapsis is nail-biting ... wasn't ever certain I would get into orbit), and wasted more fuel than I should have. By the time I get to the descent stage for the Mun, I have between 1.7 and 1.6 liters of fuel left ... quite enough to land if timed correctly. Unfortunately, I also mis-judged MOI, so the only recourse I had is to land on the dark side of the Mun. Took five crashes to nail down an average altitude of the terrain, but I just can't seem to make the final 10k meters. Another five mishaps later (first one scared the CRAP out of me and my four year old son), and I've finally given up for the night.

To the OP: This is a VERY fun and addicting challenge. Thank you . Even though I know this is a bug, it's giving me a little bit more respect for maneuvers, fuel consumption/management, etc. Also makes me appreciate those players who don't use mechjeb for some of the orbital information like I do. I wish some of this information was already on our GUI ... w/o the autopilot part of it.

3rd image in the list (the 05-39 one) is a quick spacewalk during final landing approach above the Mun, just for fun. Last image is my fuel supply at 65k meters above the surface ... I know I can make this, just haven't gotten the timing right yet. I either end up slowing down too quickly, or slowing down too slowly (and thus emergency thrusting the last 1k meters, wasting precious fuel).

Tomorrow ... tomorrow, I'll make sure Jeb's in the pilot seat

[Soralin]

Yeah, getting into orbit is the hard part, thrust too much, and you burn too much fuel, thrust too little, and you can end up falling back into the atmosphere. I was scraping the atmosphere as it was with 10L of fuel left.

As for landing, you could try jumping out and coming down on EVA thrusters if you run out of fuel. I was watching my fuel and considering if I would have to do that when I was coming down. Landing in the dark is a bit more of a pain though.

[Mindofscience3]

Because 1 glitch isn't as good as two.

24 x 0.04 = 0.96 (canard)

1 x 1.00 = 1.00 (spike)

1 x 1.125 = 1.125 (fuel tank)

1 x 0.80 = 0.80 (capsule)

-------------------------------

3.885 tons

Much much easier to get out of the atmosphere plus it gives you ~500 m/s for no fuel.

Edited August 31, 2012 by Mindofscience3

[Bluejayek]

Lol. Can you reupload the picture? It isnt working and I really want to see it. Also, what was your fuel remaining on landing?