ATEC

Stock Payload Fraction Challenge RE-BOOT

83 posts in this topic

I'll just leave this here, even though it doesn't fit in the rule.

Here's my reusable lifter which can lift 13.42t. It weighs 71.78t with the payload, so the score would be 18.70

It didn't get into 100k X 100k orbit, but was certainly capable of reaching the orbit as it had plenty of dv on 70k X 120k orbit.

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@Abastro I like the vehicle so if you send me the .craft file i will test her out to test if i can get her to full 100K orbit. If that works i will get you in the Full Rocket Recovery list

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@Abastro
Are you interested in sharing the .craft file or not if you share it i will check if you are eglible for the leaderboards!

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Posted (edited)

7 hours ago, ATEC said:

@Abastro
Are you interested in sharing the .craft file or not if you share it i will check if you are eglible for the leaderboards!

Oh I missed this. Sorry.

I don't have the exact version of it now, but possible entries are here: 

https://www.dropbox.com/sh/13b2rchjw8hioeh/AAC6VwTb2nF4ZC4MUb5P_Ioba?dl=0

EDIT: Welp, I didn't know that this one is hard to fly for an average pilots. I may try this challenge myself with these lifters.

Edited by Abastro

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@Abastro I tested the lifter and i was able to get it to the allowed orbit! So i will be adding you to the leaderboards right now!

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Posted (edited)

A submission for the Rocket Only Recovery category: the D2, a single-stage recoverable rocket with a payload mass fraction of 20.23%:

Btw, if rocket builders manage to land the rocket at the runway, would we also benefit from the extra points:

On 4/12/2017 at 7:47 AM, ATEC said:

*just for SPH SSTO* You will get 10 points extra if you de-orbit and land ON the KSC runway (so maximum amount of points for the SSTO mission will be 110)

 

For that matter, I feel that if landing a plane on the runway gets 10 points extra, rockets landed on the launchpad should get 30 points... :D

Craft file: https://kerbalx.com/swjr-swis/MassFraction-Rocket-D2

Edited by swjr-swis
imgur/forum being weird

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@swjr-swis I added you to the leaderboard!
 @Abastro Are you gonna beat him?

 

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Currently I'm working on my personal project, so not today. I would try it tomorrow, with MAMMOTH POWER!

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3 hours ago, swjr-swis said:

if rocket builders manage to land the rocket at the runway, would we also benefit from the extra points. 

A different idea for similar results: 1 bonus point for every 10% (rounded down) recovery. Ir something along this lines. However multiple recoverable stages can be tricky. 

 

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1 hour ago, Spricigo said:

A different idea for similar results: 1 bonus point for every 10% (rounded down) recovery. Ir something along this lines. However multiple recoverable stages can be tricky.

Nothing a bit of trial & error can't help us perfect. I am managing to land the rocket on the KSC area now with pretty good accuracy.

 

So I was curious how well my D2 would fare compared to the top performer of the same category in the last iteration of this challenge, @Nefrums RLS Mk1. Since the old rules allowed a minimum orbit of 70x70km, I was able to shave off total launch mass by removing one tank and shortening the fairing, and at the same time topping up the payload ore tanks. The D2b was able to put 101.537t of payload into a 70x70km orbit with a 478.373t launch mass, which puts it at a 21.23% mass fraction. Not a bad result for a single-stage rocket vs a two-stage one... I was pleased. :D I'll have to find some time this weekend to remake it in 1.0.5 and see if it maintains that performance with the exact same physics too.

 

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Posted (edited)

An entry for the Rocket category (non-recoverable), the D1b, a single-stage non-recoverable lifter reusing the D2 concept:

21.19% mass fraction, with some room for improvement (the fuel remaining probably means the X200-8 tank can be removed, which would shorten/lighten the fairing as well, although I'd likely have to accept leaving a huge piece of debris in orbit).

Edited by swjr-swis

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What the heck, I've never formally entered one of these before.  This ship isn't really an efficiency award winner but she looks nice, flies nice, and gets to orbit in a hurry with a very simple (ie overpowered) flight plan.  All the design details here:

https://kerbalx.com/fourfa/ORCA-v2-Heavy

76.6 tons of fuel delivered to 101km orbit, returned to runway on a once-around mission. Got mechjeb installed but not used during this run.  I know for sure piloting by hand cost me about ~80m/s in orbit vs the very precise SmartA.S.S. flight profile.  Fully fueled weight on the runway at start is 216,835kg. Cargo is 76,600kg.  35.33%, plus 10, final score 45.33?

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Posted (edited)

Well, given that my previous (SSTO) rocket-only entry had a little fuel left in the booster when it reached orbit, I reasoned that it ought to be possible to add the parts needed to recover the booster and still launch the same payload.  Only one way to be sure, right?

I used the exact same payload -- 1.25 m tanks to hold 2000 units of LF/O, inline Clamp-o-Tron, 1.25 m inline monopropellant tank, 1.25 m probe core, 2 fuel cells, 1.25 m decoupler, heat shield, Mk. 1 Command Pod, Mk. 16 parachute -- but I removed two RCS quads from the command pod, bringing the total to ten.

The only changes I made to the booster were addition of (after several reduced fuel test flights) nine Mk. 2 Radial Parachutes, six on the Twin Boar's integral tank, and three on the forward tank and fuel adapter, and three pairs of the medium size landing legs, plus another 1.25 m probe core and a battery to keep the probe core operating after decoupling from the payload (and its fuel cells).  The parachutes and landing legs were set up to land the booster horizontally.

Here's the .craft file.

Payload weight changed little if at all:

screenshot44_zpstzijimd9.png

The booster (hence GLOW) gained a little -- parachutes and landing legs aren't massless, more's the pity.  Don't forget to subtract the weight of the launch clamps, which won't be leaving the pad.

screenshot43_zpsxryutv2t.png

As previously, Jeb was selected to fly this mission; the expected optimum launch profile was virtually identical to that of the original entry, and he'd flown that.  Here's the vessel on the pad.

screenshot45_zpsr8ksbyah.png

And here it's coasting toward apoapsis and the circularizing burn.

screenshot46_zpsqv67zzj7.png

Circularizing wasn't perfect, the vessel wound up with apo just above 105 km, and peri just below 100, but tweaking the final orbit with RCS on the payload is within the rules, so Jeb didn't burn more LF/O to improve the orbit.  The correction maneuver required only 10 units of monopropellant (around 6 m/s).

screenshot48_zps6t6df8ja.png

And here we see the final payload orbit, well within tolerance after correction.

screenshot47_zpsasizqfwe.png

With the payload in the required orbit, it's time to think about recovering the booster (no other parts to worry about for the moment).  Even after the payload's orbit correction, the booster is still pretty nearby.

screenshot51_zpsd8oxu9hb.png

One nice thing about reentering from a low orbit -- if you pick a fairly high peri, the heat load isn't too high; engine bells can take it easily and the weight of the engines keeps the rest of the craft in the heat shadow well enough.

screenshot52_zpsda8n7ysb.png

Ground control burned the last whisper of fuel trying to get a landing on the desert continent (having failed to adquately compensate for Kerbin's rotation in setting the deorbit burn, hence reentering too far west to be close to KSC), but overshot and the booster landed in the sea.  The landing legs weren't needed, so weren't extended.

screenshot54_zpssn0akgii.png

Nothing fell off, broke up, or exploded on splashdown (previous low altitude test flights had shown that this booster lands without damage on reasonably level land, so I wasn't much concerned about a water landing).  And this was, of course, the only stage to recover from an SSTO launch.

screenshot55_zpsnasnnwdh.png

Here's the payload, still in its designated orbit.  Eventually, Jeb detached the command pod, deorbited (using only about 60% of the pod's RCS fuel for the 56 m/s burn), and returned to Kerbin, leaving the fuel tank in orbit, ready to refuel a future mission

screenshot56_zpsdxeytqjf.png

Payload mass was 14.59 t; GLOW was 117.315 t (minus .2 t for the launch clamps), for a presumed score of 8.03 (rounded, exact is 8.0271) in rocket-only recovery.  Not huge, but there's no SSTO rocket category...

Edited by Zeiss Ikon
Add link for .craft file

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Posted (edited)

It's good to see this restarted. The Stock Payload Fraction Challenge was always where I looked to see how well KSP was doing as a game. More than any other challenge (except maybe the corresponding funds/ton challenge), this one had the best players taking on the most difficult part of the game to optimize. When this challenge went inactive, it was kind of a death-knell for KSP challenges in general, and corresponded to a much lower level of activity, interest, and creativity in the game and the forums. 

Has the game changed so dramatically that the prior best (>50% payload fraction in 1.0.5) has been reduced to 35% as the best now? It'll be neat to see others try! I never understood how you are able to measure drag; how does everyone figure out that critical value??

(Also, thanks for the craft file @Wanderfound! I haven't played in quite a while, and after cutting the payload in half and semi-incompetently following the ascent profle, I was able to launch, reach orbit, and land the spaceplane on the runway without autopilot on the first try! That's a pretty forgiving design, especially with me significantly miss-guessing reentry and overshooting the runway by a lot.)

 

edit: Oh, a couple requests for @ATEC: please consider linking to the relevant post in the leaderboard. As the thread grows, that'll make them easier to browse to. Also, drop the 10 point recovery bonus for spaceplanes. All that does is obfuscate the payload fraction when every other category is clearly scored by payload percent. Make a separate category for recovery if you want to track recovery, or just require that all spaceplanes return to Kerbin. 

Edited by gchristopher
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Posted (edited)

1 hour ago, gchristopher said:

I never understood how you are able to measure drag; how does everyone figure out that critical value??

Open the in-game 'cheat' menu (Alt-F12 on Windows), go to the Physics tab, Aero, Display Aero Data GUI. The window that enables in the Flight scene shows a 'Total Drag' value (along with a whole lot other useful information).

Edited by swjr-swis

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I have a SSTO that weighs 76t with no load and can put a 36t payload into a 75km orbit, does that count for anything?

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1 hour ago, Thor Wotansen said:

I have a SSTO that weighs 76t with no load and can put a 36t payload into a 75km orbit, does that count for anything?

Screenshots...

Is that 76t with or without fuel?

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@Thor Wotansen 
1) Screenshots of launch (See the rules)
2) See if it fits the rules
3) See if you can edit it to fit a 100x100km orbit

@gchristopher
I edited the leaderboard to include the posts!
I did remove the 10 point bonus and changed it into the fact that you must land on KSC grounds

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9 minutes ago, ATEC said:

@Thor Wotansen
I did remove the 10 point bonus and changed it into the fact that you must land on KSC grounds

Sorry - just to clarify, is it KSC grounds or KSC runway?  KSC grounds is MUCH easier.  (Though I suppose you could land on the grass and taxi onto the runway, like we all do in career games to maximize recovery with hard to land planes)

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@fourfa See the rules. It clearly says

You MUST Land on KSC Runway grounds. That is the runway and those green steep pieces of grass

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yeah, it does clearly say that.  Then, you clearly said something different in the part I quoted.  Just trying to make sure there's no confusion

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@fourfa True but after i read your comment i thaught it would be a bit harder to make you land on KSC runway grounds

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Posted (edited)

Alright, my Mk 3 SSTO I've named Róta delivered a 36.54t payload to a 100km orbit and returned to the KSC runway.  The Róta weighs 115.725t with fuel and payload, which gives a payload fraction of 31.57%.  This was also my first descent from orbit to the runway without using the engines in the atmosphere.  So without further ado, I present the Róta.

 

Edited by Thor Wotansen

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Hmm I can remember this challenge from 2 years ago or something... but interesting! I will give it a try :)

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Posted (edited)

OK guys, I'm an interplanetary spaceplane person and I don't normally go for payload mass,  in fact hardly ever build freighters at all.   So,  this one probably starts out with several wrong ingredients as a result.  

Nukes? Wrong !  

Aerospike?  Niche engine, worthless.

Mk2 body?  Just .. Say .. No.    

This is a partially re-usable spaceplane, the whiplash pods, rapier engine and aerospike get discarded, but the body of the ship with its two nukes are capable of re-entry and could ditch in the water by KSC.   This puts it in the "unlimited category", though it is mostly recoverable. Dumping the Whiplashes kinda makes sense on account of them being so cheap, doing the same to the rapier which costs 3x as much per weight saved is a bit more questionable...  but economics is not part of this challenge.

31.5 Payload

73.915 Gross Mass

 Total 42.616 Points

 

Oh well I didn't even beat the 100% re-usable craft.      BTW it's a bit of a weird challenge, ore is not a payload you'd normally launch out of kerbin.   Maybe a Xenon powered moho mission is more realistic.

https://www.dropbox.com/s/nxfwt2i58v7gekm/Anduril.craft?dl=0

Edited by AeroGav
imgur absolutely determined to mess up the order of the pics

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