Stock Payload Fraction Challenge: 1.0.5 Edition

[Radam]

But it's not biggest weight to orbit, it's biggest payload, so you cannot use any part of your payload on the process, and you need to eject whatever you used to bring it there.

Neat rocket, by the way, haha.

Right, it was more like a big middle finger to the concept of aerodynamics. Still, somewhat comparable "payload".

[Commander Jebidiah]

Time for my entry, in fact I believe this is the first Challenge I've Entered.

My rocket is called the 'Fraction Rocket'

Stage info:

Stage 1: 1 Central Core with 1 RAPIER and 8 Outer cores with 1 RAPIER each.

Outer cores separate at 20km.

Stage 2: 1 LV-N with 1 Jet Fuselage

http://imgur.com/a/LRgHii

Payload Fraction of 19.345% (To 3 DP)

[Red Iron Crown]

I really should disqualify that entry for excessively long launch clamps, but it looks like you had extra fuel in a couple of your stages so I don't think it affected your final payload fraction (if your margin had been tighter it would have been no-go). Plus I don't want to discourage you on your very first challenge entry. Added to the leaderboard.

[mightyhuhn]

ok next try:

http://abload.de/img/challengev21bquhd.png

http://abload.de/img/challengev22t2ujj.png

http://abload.de/img/challengev24cvurx.png

100/11.44*3.58=31.2937062937063 right?

- - - Updated - - -

it's 11.6 in the sph why is it 11.44-11.43 on the runway? buggy air intakes?

[Red Iron Crown]

Looks legit mightyhuhn, added you to the top of the board.

Not sure what causes the editor/flight disparity, it used to be massless parts but I think that has been fixed to a degree in 1.0.

[Starwhip]

Ew, bleh. Only 19.1%.

More testing required. Rocket is not efficient in any sense of the word.

[Radam]

I heard kerbin was supposed to have atmosphere...

Asparagous seem to help very little or almost nothing.

85.7t payload with a 369.6t launcher, 23.187%

lets try some aerodynamics now.

On the pad after fairingfication...

http://images.akamai.steamusercontent.com/ugc/534018071203213662/97DCA32A9E4FAA077EBC90A39E57C505B74C9AB9/

Just cruisin...

orbit:

http://images.akamai.steamusercontent.com/ugc/534018071203215485/969176E2C664DD68AC07166DCBA8A3AD9D3C4A43/

Basically: about 90.5t in orbit (fairing adaptor is still on), 375.8 on the pad == 24.08%

Mechjeb is reporting I used about 3000 dv. http://images.akamai.steamusercontent.com/ugc/534018071203235039/45558DA5802BD355E9B466C74B7C55B43EC2FF4F/

Edited April 29, 2015 by Radam

[KerikBalm]

Somebody told me I should post this to the stock payload challenge:

http://forum.kerbalspaceprogram.com/threads/117535-No-more-SSTO-s?p=1881501&viewfull=1#post1881501

At first glance, its rather mediochre... 487 tons on the runway, and I release a 108 ton payload into a 79x79 km orbit... 22%

But then you should note that I have 54 tons of oxidizer left, and 40 tons lof liquid fuel left, and plenty of space in the cargo shell to add more stuff.

Its simply a matter of removing fuel from the SSTO tanks, and adding the same mass in the aero shell.

Payload + spare fuel results in a 202 ton payload from a 487 ton craft... 202/487 = 41.47% payload fraction.

I'm already wondering what sort of results I could get if I two stage it...

[Red Iron Crown]

Radam, I've provisionally added you to the leaderboard as your entry looks legit, but I have some questions:

- Is the faired version still asparagus staged? The dV readout makes me think so given the number of stages, but I can't make out any fuel lines in the pic.

- Does your rocket have a name?

- Most importantly: Was any fuel remaining in the lifter when you separated the payload? I ask because the orbit you achieved does not meet the 70km periapsis challenge requirement, nor does the SMA equal a 70x70km orbit, and it looks like you were cutting it very fine indeed on circularization dV.

KerikBalm, I'll hold off on adding you just yet. I can't accept leftover fuel in the lifter itself as the different mass distribution in the putative compliant version may affect the plane's performance. It does look very, very promising though, I hope you put together an entry.

Edited April 29, 2015 by Red Iron Crown

[Radam]

It was, no name, I think there was 1 ton left, didnt really make sure it was more than 70x70.

[Red Iron Crown]

Thanks for the quick reply, Radam, your entry is confirmed.

[KerikBalm]

"KerikBalm, I'll hold off on adding you just yet. I can't accept leftover fuel in the lifter itself as the different mass distribution in the putative compliant version may affect the plane's performance. It does look very, very promising though, I hope you put together an entry."

Well... then there's another rule that should need clarifying... Suppose I just slapped on another 4 *empty* 200-32 tanks (ie, 6 fold symetry around the orange tanks, instead of 2 fold) and then added FL-T800 tanks with symetry to the front and back... The empty tanks would barely affect the weight distribution on such a massive craft, but I could then pump all my leftover fuel into them... would they then count as payload?

I wouldn't have been draining from those tanks, and the fuel pumped into them would of course have been deadweight the whole flight (unless you consider that it may have had a use in balancing the craft).

Basically, can I put empty fuel tanks into my payload, and then pump remaining fuel from the lifter into them?

Anyway... I designed this as a cargo carrier, so the CoM and CoL are right where the payload is, it flies just as well with the aeroshell empty. It shouldn't affect balance at all... it just makes estimating how much fuel to remove from the main tanks into a non-issue.

I would hate to try and put 202 tons into orbit, but then fly a slightly worse ascent, and come up with a 69*70 orbit...

I should be able to make the changes and try again tomorrow... and I can stop at a 70km orbit instead of 79x79.

I'm also wondering (if I'm trying to maximize payload fraction), if it might be worth it to put some LV-Ns on it for the final circularization burns....

Basically, I need to figure out how much of the burn can be done by LV-Ns...

If one part of the burn used 20 tons of fuel... if a pair of LV-Ns could do, they'd be using 340(is the the new KR-2L Isp?)/800 = 8.5 tons... saving 11.5 tons at the expense of 6 extra tons of engines...

I was already contemplating doing this, and had an idea where to stick the LV-Ns to not add to drag (see my post on interstage fairings not working in the SPH).

Its worth noting that this desing wasn't designed with payload *fraction* in mind... but rather just *payload*

I don't know if adding more jet engines can help, as I lose a lot of liquid fuel during ascent... with the need to ascend, dive past mach 1(since passing mach 1 will increase the engine output, and if it models it correctly, drag coefficient starts to drop post mach 1), level off, and ascend again- slowly at first but then to a 20 degree pitch.

I'm sure someone can beat this design... its still the early days of 1.0... but based on postings I've seen so far... I do seem to have made the most progress with heavy cargo spaceplanes.

Still.. maybe a small and light spaceplane will out-perform my behemoths...

Edited April 29, 2015 by KerikBalm

[GoSlash27]

Excellent challenge!

I'm in the process of analyzing this very problem, and (like a dope) I left the results at work!

Hopefully I won't brain-fart tomorrow and can submit a competitive entry.

Best,

-Slashy

[tetryds]

There should be a separate section for people using any kind of non-visual mod, IMO.

We got some nice entries here, that is cool.

I went for a fixed design approach, to see how far I could get without changing it.

[Red Iron Crown]

...Basically, can I put empty fuel tanks into my payload, and then pump remaining fuel from the lifter into them?...

I would greatly prefer that entrants not do this, as it is not in the spirit of the challenge. Launching an empty tank as payload and simply transferring whatever fuel is remaining into it once orbit is established removes a large part of the challenge of designing the lifter and payload to match each other. The payload is meant to be inert and unchanged, and replaceable with some other non-fuel payload in the same spot with similar results. When drafting the challenge I considered specifying ore tanks as the payload to sidestep the issue but I felt this was too restrictive in very small and very large designs.

Of course, I am not really able to police that rule effectively so I am depending on the honor system and honest competitive spirit of the participants to do it for me. Hopefully I won't be disappointed.

At any rate, I don't think this restriction is overly burdensome for you, your design looks like it will be very competitive and by the sound of it you're already enjoying thinking about how to best solve the problem.

There should be a separate section for people using any kind of non-visual mod, IMO.

This is primarily a design challenge, and an iterative one at that. Information mods reduce the tedium of calculation for those that want numbers, and autopilots like MechJeb or kOS provide repeatability and prevent good designers with more modest piloting skills from being penalized. The main objective is to discover how lean a lifter can be made with the stock parts and physics, not who can fly the best by the seat of their pants.

Edited April 29, 2015 by Red Iron Crown

[zekes]

Radam, your entry is interesting but doesn't decouple its payload so I'm afraid I must disqualify it. I invite you to throw something on top of that thing and see what it will do!

mightyhuhn, sorry, but the intake does break that rule. Sorry if I seem a stickler about it but it's a slippery slope that I'd rather not start down. Think it would work with a radial intake or two on the booster?

zekes, cool, I'll wait on your pics before adding you to the board.

SanderB, thanks for reworking, I'll update your leaderboard entry.

Okay, I have Kerbal Engineer so I can use that for the accurate Lifter weight.

Cira IV-27: 1,929.93 tons

Payload: Three Super Large Tanks (302.4 Tonnes)

302.4/(1929.93 plus 302.4) = 13.546384271%

Not as good as I expected, but given that that's 300 tonnes in one big go, only two stages (no fancy staging and such) it's not that bad.

[Red Iron Crown]

Zekes, think you could add some pics of the ascent and the delivered payload? That looks like an enormous rocket and I'd like to see more of it in action.

[Shrike99]

Alright, after messing around with all-rocket designs, and failing to get above about 22.5%(Kudos to Radam for somehow getting 24!!!) i decided to go for a hybrid approach, and have managed ~27.29% on my third revision, though i believe that with some tweaking and a more optimal ascent profile i can get more. I decided to put a mostly full ore tank into orbit. No real reason, other than it was ballast, and couldn't attribute to the craft

Javascript is disabled. View full album

I will post a flight plan and craft file after some further messing around, if anyone is interested, although i daresay you could just build your own take on it from the pictures

Edited April 30, 2015 by Shrike99
Embeded imgur album

[Red Iron Crown]

Nicely entry, Shrike99, and and an impressive result. Ore is an excellent payload, it is denser than fuel so is more compact for the same mass. I'll add you to the leaderboard.

[Maelstrom Vortex]

Anyone be willing to help me on a design that carries a massive payload, makes it into space, but not quite into orbit? If you are.. pm me.. I'll let you see the .craft file on what I've got so far and we can go for a shared award and perhaps the most awesome spaceplane built for v 1.0 because I intend on it being able to do EVERYTHING... literally. You'll see.

[metaphor]

Here's a simple single stage rocket with 22.7% payload fraction:

Javascript is disabled. View full album

[Maelstrom Vortex]

Rockets are pretty easy. I'm trying to do an SSTO space plane with massive lift capacity.. and I almost have it. I get it to 75k, but just can't seem to get it over the orbit hump.. and I REALLY don't want to add stages..

[zekes]

Zekes, think you could add some pics of the ascent and the delivered payload? That looks like an enormous rocket and I'd like to see more of it in action.

This was just a mass test, to keep fairing weight down.... final payload at orbit was 302.4 tons.

You can download it here: http://forum.kerbalspaceprogram.com/threads/117484-Cira-IV-27-Heavy-Lifter-300-Tons-to-LKO-By-Zokesia-Skunkworks%21

[cybersol]

Here's a simple single stage rocket with 22.7% payload fraction:

Wow, I actually didn't believe such as simple SSTO could pull off that payload fraction. So I rebuilt it and tried launching it... and failed to reach orbit. So I tried launched it over and over and eventually got it to 70km x 118km orbit. It turns out this rocket is actually a fantastic trainer for the new aero. It has just enough dV to get to orbit with a near optimal ascent profile. Plus it turns out that profile is crazy shallow and high mach compared to what I expected. 1200 degree parts would have melted with the near optimal profile.

[Radam]

Hmm, someone try disabling all drag forces and do a run as if there was no atmoshere. As it even seems that asparagous is dead becouse it keeps a constant twr.