Think Small! Smallest Launchpad to LKO Rockets

[quietsamurai98]

I was reading about the Minotaur I, the type of rocket launched by NASA on Tuesday, when I saw that it weighs only 36.2 tonnes. Combined, an orange fuel tank and a large decoupler alone weighs 36.4 tonnes.

So, lets abandon the big lifters weighing 100's of tonnes, lets get tiny!

Objective: Get to LKO (Ap/Pe between 69 and 80 km) using the lightest ship possible with as little spare delta v left.

Rules:

USE MECHJEB for ascent.

No jet engines.

No infinigliders.

Any submission may be rejected if it goes against the spirit of the challenge, even if it follows the letter of the challenge (Remember the 30 sec altitude challenge and decouplers? No repeats of that).

Scoring is inverted (best score is lowest), formula:

Spare vac dV + Prelaunch Mass + (69km-((Pe+Ap)/2))

Submission must show mass and ship before launching, and ship Ap and Pe after orbiting.

Scoreboard:

1. Quietsamurai98 [OP] | 379.6945

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3.

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[quietsamurai98]

My Entry:

Total Score: 370+8.73+(69-((71.446+69.483)/2))=379.6945

[dawg]

Way too big bro... I'm not sure if I have enough for a score here, but here's what I've got:

Before launch:

In orbit:

If the Oscar B had the right fuel:oxidizer ratio I suspect you could do it with a single Rockomax 48-7S rocket.

Believe it or not, the hardest part of my launch was getting enough electricity because RCS will suck it all down before you get to orbit and a battery burns another 35-40dV... The probe core and mechjeb actually use it faster than the engine will recharge it even when at full throttle. It turns out that this engine has just enough vectoring to get you in the right orientation to get into orbit without it. I could probably burn some dV on a chute and actually bring it home, but it'll run dead in about one orbit or so...

I could get a better score with more weight, though, since you want a minimum of dV remaining.

Also, this is a grand total of 4 parts.

Edited November 21, 2013 by dawg

[dawg]

I made an even smaller one... Much more complex, though, and it does use Oscar Bs and Toroidal fuel tanks.

Before launch... 1.52t!

In orbit, with only a tiny bit of fuel left...

It's 2 Oscar Bs, an Octo2 core, a 48-7S, MJ (on an OB), and a stack of Toroidal fuel tanks. End dV was 87m/s, starting at 1.52t, with an ap of 70,585m & pe of 69,256m...

I'm not sure it's possible to go lower in mass and actually get off Kerbin. The only smaller engine is the LV1, which I don't think produce enough thrust to lift a single fuel tank off the pad in Kerbin's gravity, but I could be wrong.

[Songi]

This sounded like something I could do!

first try,

1.27 T, made it to 70k orbit with 825 dV left

[Sirine]

Same as "post number3" but, no MechJeb.

[Songi]

Without mechjeb I dont think I could do as well haha

Edited November 21, 2013 by Songi

[RexKramer]

Not sure why there's the penalty for having DV left over at the top. But anyhow…

I built a ship weighing 2.41t, it reached an orbit of 79597/79414 with 1131 DV left over. That's enough to go to Mun. Which I then did, and was able to reach a circular Mun orbit just as I ran out of fuel. With all the DV I had left at 80km, the score sucked, 1123.2045.

So I cut my fuel in half. New ship had an initial mass of 1.29t. Reached orbit of 79969/78488 with 443.6 DV left. Score worked out to be 434.6615.

That ship consisted of:

1. Z-100 Battery

2. OKTO-2

3. FL-T200 tank

4. (3) OX-STAT basic solar panels

5. 48-7S small engine

That's 7 parts, 1.29T. I don't qualify for the competition because I don't use any mods, not even MechJeb, which was a stated requirement for the competition.

Wish I knew how to post pictures, I'll try to figure that out and post some.

[dcethe]

66.9 I think

sorry I can't find a place to host images that works.....

I took some pictures though and got even lower that 66.9

Edited November 21, 2013 by dcethe

[Sirine]

Made a video... with "Open Broadcaster Software". I just want to test out the recording software...

Anyway...I'm not using MechJeb...so, can't apply to the challenge due to not following the rules.

[Kasuha]

Hmm so the less optimal ascent path you use the better score you get? Doesn't sound very challenging to me.

[Rhomphaia]

EDIT: Better attempt

Score: 21.7255

Edited November 21, 2013 by Rhomphaia

[Johnno]

I guess my entry won't be approved for two reasons, I didn't use mechjeb and my AP shot past 80km (82), didn't bother turning around to fix it. Just want to point out that one could burn fuel already in orbit to improve their score.

Similar challenges have been done in the past, with the new thin 1.25m fuel tank and the 48-7S engine things can be slimmed down. With a perfect/mechjeb launch it might be possible to drop the ant/oscar-b tank combo and get to orbit with just the 1.25m tank.

To orbit with 0.826 tons

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[dawg]

Heh... I've never used the FL-T100. That's a better ratio than mine. Impressive.

This is practically model rocketry...

[dawg]

After learning about the FL-T100, I did an almost identical one to #12 with an octo2, T100, 2x Toroidals, and a 48-7S. Total mass was 0.97t and it made it to orbit with 80m/s left over.

I wonder if you could launch something almost that small with a lawn chair on it for an ultra-light lander for the Jool moon challenge. I just got a couple large tugs assembled in orbit with ~16000dV; I just need a command pod with a hitchhiker and a handful of landers that are efficient and can carry a single Kerbal...

[RexKramer]

Hmm so the less optimal ascent path you use the better score you get? Doesn't sound very challenging to me.

Exactly. Seems to be very little value to building a light ship, but high value placed on having one which runs out of gas the instant it achieves orbit (thus stranding it…). With very light ships, even a trace of fuel left over yields a lot of DV.

[Songi]

0.66T made it to orbit with only 106dV left (mechJeb set to 73km orbit)

3 parts, tank, mechjeb, and engine. Not sure if that's fair tbh

[Johnno]

0.66T made it to orbit with only 106dV left (mechJeb set to 73km orbit)

3 parts, tank, mechjeb, and engine. Not sure if that's fair tbh

Within the constraints of the challenge it's fair, and pretty much the ultimate winner. Since I don't use mechjeb (which I wasn't aware could be used as a control part) I had to add a probecore, do that and you lose about 600dV.