Farthest Distance Traveled in 10 minutes

[numerobis]

That separatron top stage is pretty sweet! I had no idea I could so easily tack on another km/s.

[tavert]

Got the idea from Nao . This type of challenge is one of the few places where 1 km/s is MOST useful when delivered entirely in 3 seconds.

[metaphor]

I used an Oscar-B tank and an ant engine as the top stage, it weighs less than the separatrons and has 1500 m/s delta-v instead of 1000. It does take 2 minutes to ramp up but you still come out ahead because you have 500 m/s more for the next 5 minutes.

Question, are you all doing a gravity turn at all or just burning straight up? I've tried both and gravity turn seems to come out slightly ahead but I can't tell if I'm doing it right.

[numerobis]

The turn should come out ahead: if you fight gravity for the first 4 minutes, even if on average during that time it's just 4 m/s, that's about 1 km/s you lost to gravity. Some of that you can't help but lose of course. With jets, you also want to stay low a bit longer so you can get maximum benefit from the jets.

I'm currently trying to switch out the SRBs in my design for fuel. The impetus is that I'm carrying 3 MN of mainsail thrust that I'm not otherwise using, so instead of tacking on 30 tonnes of SRBs to get 2 MN for 30 seconds, why not tack on 30 tonnes of liquid fuel to get 3 MN for 30 seconds. And there's a bonus: the fuel has less drag than the SRBs. The theory works, but then for some reason the same spacecraft that reliably worked before now falls apart.

The limiting factor in my design is the part count. I need to work on that...

[NeilC]

Very nice, I like the SRB + radial + LV-1 combo for the payload! That's a solid 3 minutes.

I'm always surprised to see lifters that are wider than they are tall... Your outer asparagus boosters last less than 15s! In my designs I would tend to distribute the fuel in your outer ring among the inner nacelles.

Not saying there's anything wrong with yours, it's probably more efficient overall. I guess the dry mass of those tanks would add up over the nacelle's whole burn time, even though it's only 2 tons. Since everything's still free in KSP, might as well discard 4 giant engines in 15s!

[metaphor]

I guess the dry mass of those tanks would add up over the nacelle's whole burn time, even though it's only 2 tons. Since everything's still free in KSP, might as well discard 4 giant engines in 15s!

Well since the challenge has a limit on fuel, not mass or cost, you can add as many engines as you want. I actually tried something like this:

but that didn't seem to work as well.

Edited May 13, 2013 by metaphor

[NeilC]

Another attempt with the same launcher, this time tweaking the payload for higher TWR at the expense of mass. 8 stages and over 2 minutes burn time after the Rockomax separates, and nothing under 5 TWR. Tops out over 12Gs when the final probe body gasps its last puff of fuel.

Better results, at 3,524. But still no hope of 5M. I don't think I've got it in me to rejigger my launcher.

[numerobis]

I present: the Hellbat 2b.

5894 km using 49997 units of fuel, oxidizer, and solid fuel.

I have defeated the part count limit by using wings and tricouplers, rather than masses of cube struts, which let me bump up the engines to over 100. It's also a more solid attachment, so I lose fewer rockets to having engines pop off -- in fact, I never lose rockets to that anymore (not that there aren't other reasons for catastrophe).

Also, I decided to think of the jets as being a booster to help the rockets improve their Isp, rather than being a replacement for them. That lets me burn a lot more fuel: when I ditch the jets at 1 minute in (nearly 30km, going 2km/s orbital), I have more fuel left than my first submission had on launch.

One fun thing is to get to terminal velocity as fast as possible; it takes me 5 seconds (that picture is a good view of most of the spacecraft, by the way).

What made this work:

1. MOAR ROCKETS. By changing my thinking about the role of the jets, I am easily able to slap 50k units of fuel on my spacecraft, and just run the rockets all the way up. Not pictured, there's a first stage consisting of a 4-tonne pill of fuel covered in separators, just to use up my entire fuel allowance.

2. MOAR little tiny ant rocket. Just tacking that on my prior submission helped a bit (but not enough for me to resubmit).

3. Drastically reduced part count for the jets. Before, I was using 7 cube struts per engine. Now, I'm using two wing segments, a cube, a tricoupler, and a fuel line for every three engines -- 1.67 structural parts per engine rather than 7. I also reduced the intake count to just under 3 intakes per engine rather than just under 4. This lets me add a lot more engines: on launch I have 108 jet engines with a part count of 834 rather than 83 jet engines with a part count over 1000. (I also have 43 separatrons, 6 mainsails, and 4 T30s: 161 engines all firing simultaneously.)

4. Removed the T45 stage; instead, I use the 24-77s on my penultimate stage as the thrust vectoring engines for the two T30 stages. Otherwise I was carrying the T45 all the way through the atmosphere without using it. Also, I reduced the fuel on each T30 stage from 4t to 3t, to improve their TWR.

5. Turn much more sharply than the norm. I turned starting at 6km, and ended the turn at 30km, with a 60% turn shape, and corrective steering off. That kept my path closer to the prograde vector than other attempts, which means less waste.

Now, how to improve -- surely we can hit 6000 km?

a. The last mainsail stage is active for about two minutes. I'm pretty sure it would benefit from being converted to a T30 cluster -- or, better yet, a T30 asparagus maintaining a TWR about 5 all the way. The second-to-last one is active 90 seconds, which might also be better done as a cluster or asparagus, but at some point the part count monster rears its head.

b. I still had a quarter of my fuel left in my jet stage. I should increase the number of jet engines by 25% -- and wouldn't you know it, there's room to do exactly that quite easily! This is equivalent extra thrust to an extra two or three mainsails, so it's quite significant. I should add a few intakes to compensate, but not 25% more.

c. With enough patience, I could remove the fuel pill and replace it with an equivalent amount of fuel in separatrons. That would help boost the rocket to terminal velocity faster, and separatrons have wonderful TWR. The larger SRBs help a lot at first, but later in flight they are marginal compared to a liquid rocket because they have extra drag. I'm going about twice the terminal velocity of 0.2 drag items (actually a bit more). That means I need TWR of 5 for liquid-rocket engines and fuel. Moving a SRB at the same speed requires a TWR of 7.

d. I should investigate ascent profiles a bit more.

Edited May 14, 2013 by numerobis

[NeilC]

Any interest in posting your .craft file, numerobis? I'd love to help you tweak ascent profiles, but I don't have the heart to create a clone of that behemoth.

[numerobis]

Sorry, I hadn't see your request!

I don't have the .craft handy right now, but it's actually fairly straightforward: a fairly standard asparagus rocket on top.

Then the jets layer which as you can see consists of copies of the pattern: two wing segments (or a wing and a Mk2 fuselage), under the second, a cube strut, to which I attach a tricoupler and three jets. String fuel lines from the fuselages to the tricouplers, five tricouplers per tank (I'd placed four, and didn't run my tanks dry).

Then a bit of fuel on the bottom, with a couple more mainsails.

The intakes I just spammed all in the same spot (in fourfold symmetry) with clipping off.

There are shockingly few struts. I placed one strut from the end of each wing to the end of the next wing in a circle around, and on each stage I have four struts to the next stage. And in fact, some of the struts failed (I'm not sure if it's roundoff so their raycast fails, or if it's that I accidentally wasn't in symmetry mode).

[underthing2]

Here's my attempt. (May I ask if I can do it again? I don't think I topped it.)

Album:

http://imgur.com/a/fgZey

Stuff Used:

6 FL-T 800s

1 Rockomax Jumbo-64

3 RT-10 SRBs

6 Rockomax RT-77s

1 LV-1

With a total of 130 parts and 10670 units of fuel.

Edited May 21, 2013 by underthing2
Forgot the list

[numerobis]

You can do challenges as often as you want, typically. But you're missing the readout of the resources at the start of your mission.

[numerobis]

One thing has struck me: the TWR is much better for aerospikes than for a T30, if you're flying at twice terminal velocity -- which I am. Expect a new model soon...

I've also discovered that KSP-X has a quadcoupler, which reduces my part count per jet engine. That means more jets.

[nuker132]

I would lie to add my entry of the:

"OH GOOD GOD" Craft MK7

Using no fuel and only physic breaking powers, it demolishes everything.

I hovered over the engine so you can see that I didn't use any Part editing.

At the launch pad, quite stable.

And then when I decouple the air intake at full throttle, THIS happens.

Just a map view for comparison:

And the flight log.

I don't know if this properly qualifies for using a physic glitch although I think it does. it's your choice to put it in the leader-boards though.

[lukerules117]

the fuel limit is way to low, the orbiter I use has about 70000units of fuel on the first stage.

[A Fat Pokemon]

Entering the FTL egg

I actually used 2 different crafts, as I already launched the first one before the 'after launch' screenshot,' though it doesn't make much of a difference with this thing

Hehehe...

[zarakon]

What is that thing?

[Nalin_Airheart]

Someone just kill me...I had two designs, one was a 75fps serial stager, one was a 10framerapes/day monstrosity made to the maximum fuel limit.

M-1 (Serial Staging)

Altitude: 2,191,415

Total Fuel: 11,365

M-2 (Lag Star)

Altitude: 1,000,497

Total Fuel: 45,233

Can't find the BBCode option for Flickr anymore, here's the whole Photostream, if you want more pics I can give you every screenshot I took during the hour and a half I was doing this.

EDIT: This was done in the 0.18.3 Standalone Demo :3

Apparently I'm missing the F3 Screenshot at MET:0:01. I'm going off of height instead of distance traveled but they're almost the same because I launched in the Solar Escape window and went straight up to maximize my efficiency.

Edited May 26, 2013 by Nalin_Airheart

[A Fat Pokemon]

What is that thing?

The most efficient craft you shall ever know.

It enslaves the Kraken as its power source.

I know that you said it doesn't count if its a physics glitch, but what if its a controlled physics glitch?

Edited May 26, 2013 by A Fat Pokemon

[zarakon]

The most efficient craft you shall ever know.

It enslaves the Kraken as its power source.

Sorry, but the Kraken counts as infinite fuel, and the limit is 50000

[numerobis]

I would lie to add my entry of the:

"OH GOOD GOD" Craft MK7

Using no fuel and only physic breaking powers, it demolishes everything.

What's the craft file for it?

BTW: NeilC, I screwed up and wiped out my .craft file when upgrading to 0.20, sorry! I shall have to build a new one, bigger than ever now that I'm not hitting swap (when I get free time).

[numerobis]

I poked at this again. 5426 km using only rockets.

I'm using KSPX for the half-tonne fuel tank and the small thruster; that adds quite a bit over the top-stage combo we were using before (an oscar/ant stage and a 1t/24-77 stage). I'm also using the skipper from the latest version of KSP.

I also got tired of lag, so I did another balanced mod: I made a 2.5m version of the aerospike with 4x the thrust and 4x the mass. This saves me about 100 parts. The resulting rocket isn't my most realistic-looking ever:

[Nalin_Airheart]

I don't know the original diameter of the aerospike so I'm just assuming 1m but according to basic geometry and scaling. Perimeter^1 Area^2 Volume^3

The actual volume would increase by the scale factor cubed. Your modded part might not be the most realistic as a result. I might be wrong, just putting this out there.

EDIT: I don't think there's anyway to calculate the thrust or ISP from a scaled engine either but larger is usually less efficient with chemical engines.

Edited June 22, 2013 by Nalin_Airheart

[numerobis]

You have four times the area, so you can put down four times as many nozzles. Using more volume would require actual engineering.

(In truth, putting down four times as many nozzles is also imperfect, since in reality they have a tendency to fail, so you've increase the probability that some nozzle fails. But KSP rockets are perfect.)

[metaphor]

That double helix rocket is a work of art, numerobis.