ATEC

Stock Payload Fraction Challenge {1.3.x Reboot}

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This is a 1.3.x reboot of the Payload fraction challenge
Original 1.0.5 thread is here
1.2.2 Reboot is here

The Challenge:
You must build and fly the most mass-efficient lifter possible for flying to LKO
(Orbit must be 90km Pe min. Equatorial, Circular orbit)

The Rules:
- Stock parts only. KSP Version 1.3.0 - 1.3.9 only, (Earlier entries like 1.2.2 or 1.0.5 should be posted in their respective threads)
- No cfg editing, save editing, debug menu or anything else like that.
NO physics exploits, (like infini-glider). The craft must be lifted by trust and aerodynamic lift alone
- Payload must be mounted on a decoupler or docking node and seperated from the lifter in a stable orbit with an equatorial orbit of 90km Pe min. The decoupler / docking port must stay with the lifter
The payload MAY NOT have any form of engines (Lf + Ox, nuke etc. etc.)
- The payload MUST be a DEAD WEIGHT until decoupling and after that only the usage of RCS and/or SAS is allowed to fine-tune the orbit
- Entries must be a single launch, with no interaction with any other vessels already in flight or launched afterward.
- If you use the offset tool the part MUST be visibly attached to the rocket (attach a strut or something)
- The base of the lifter must be close to the pad surface, preferably touching it. No kilometer-high launch clamps please.
- Don't clip functional parts
- Images or video of your design is required for entry, showing launch mass, payload mass in stable orbit, and enough in between to show how your vessel works. (Must be sent as a imgur picture library) Craft files would be the best so we can all learn from each other's building techniques
- You need images of the design in the VAB

- You need an image of the design on the Launchpad
- You need an image of the design in Sub-Orbital Trajectory
- You need an image of the payload in orbit (Mass of the payload MUST be showing (the kerbal button in the right of the HUD)
- Video of the full launch would be the best!

Permitted Mods:

- Visual mods (like scatterer)
- Autopilot mods (Like mechjeb 2)
- Informational mods (like KER)

Forbidden Mods:

- Anything that modifies stock parts or that adds new parts
- Anything that changes the games physics

The Scoring system:

Please add the category you are running for in your entry

The maximum amount of points is 100 and you can define your score by doing:

PayloadMassInOrbit / TotalLaunchMass * 100

Higher is always better, and the score will be rounded to two decimal places.

All the categories habe been added so you can start sending in crafts!

Unlimited: Use any propulsion to get into orbit, no recovery needed

Unlimited Recovery: Use any propulsion to get into orbit, all stages MUST be recovered

Rocket Only: Rocket engines only (no ions, jets, nerv's or Rapiers in open cycle mode), no recovery necessary.

Rocket Only Recovery: Rocket engines only (no ions, jets, nerv's or Rapiers in open cycle) all stages MUST be recovered.

SpacePlane SSTOAll engine types are allowed, must be launched horizontally from the KSC runway. 

*just for SPH SSTO* You MUST land on KSC Runway grounds!

The Leaderboard:

Unlimited

Unlimited
Recovery

Rocket only           Rocket only
Recovery
SSTO SpacePlane
29.2% by @SanderB using this rocket   28.23% by @Fauble2000 using this rocket   50% by @AeroGav using this SSTO
29% by @Laie using this monstrosity    27.6% by @Laie using this rocket   41.87% by @Eidahlil using this SSTO
27.336% by @Fauble2000 using this rocket   27.2% by @SanderB using this rocket    
         
         
         
         
         
         
         

Noteworthy Entries:

Spoiler

So why would @Laie do THIS
 

 

Beaten Fractions:

Spoiler

Rocket Only:

26.5% by @Laie using this rocket
25% by @Laie using this rocket
18.58% by @SanderB 
using this rocket
26.5% by @SanderB using this rocket

*Gotta love one-up manship*

 

SSTO SpacePlane:
43.7% by @AeroGav using this SSTO

 

Edited by ATEC
Rules

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On 11/13/2017 at 7:04 PM, ATEC said:

- Payload must be mounted on a decoupler or docking node and seperated from the lifter in a stable orbit with an equatorial orbit of 100,000m (max 10% above or below the 100km mark). The decoupler / docking port must stay with the lifter

For this iteration, may I ask you to specify this one rule a bit better? Taking this as it's written, one could place the payload on a 90x90km orbit and still be allowed - might as well just simply state 90km as the minimum Pe.

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Rocket Only (no recovery) 1.825/9.825 = 18.58% to 90km Pe orbit obviously better is possible because payload has some excess Ap.

 

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Why are autopilots forbidden? The original challenge allowed them, and most of the entries used them. I'm entering a small overpowered spaceplane, but I'm somehow unenthusiastic about flying a true heavy "payload fraction" spaceplane up there manually, it's just too tedious. :(

https://kerbalx.com/juzeris/Tug-F

Weight at launch - 53 448 kg

Payload delivered - 22 380 kg

Fraction = 41.87% ?

Rather inefficiently brought back 1 980 kg of fuel, but that's on me. :D

I used MechJeb, but, as can be seen in the video, only the info readouts were used.

 

Edited by Eidahlil

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On 11/20/2017 at 4:45 PM, Eidahlil said:

Why are autopilots forbidden? The original challenge allowed them, and most of the entries used them.

^^ This. Once you've flown 100 or more flights where you have to carefully simulate just the right analog input by tapping an arrow key at JUST the right frequency, it's time to recognize that being good at that skill is a silly life goal. 

Buying a good flight joystick is an option, but using an autopilot to hold the controls at exactly 43% up is fine too.

Autopilots should be permitted for this challenge. All the people who achieved good payload fractions used understanding of design and aerodynamics, and the flight portion came down to figuring out the right flight profile and engineering a craft that could fly it. Skillfully timed key-mashing shouldn't be part of the contest just because they don't own a joystick. 

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I submitted this craft in the old thread.   Was created in 1.3.0 so is valid to enter this one.    Oxidizer free lifter,  43.7% payload fraction, no autopilot,  just set the thing on prograde hold.

Could probably improve it with trim flaps, and more liquid fuel (it is fuel limited, rather than thrust limited)

https://kerbalx.com/AeroGav/partridge

re-entry - you can see it's rather slick so wing lift keeps pushing out our AP  - we end up "going around" on the first re-entry then I create drag with pitch, cargo bays and landing gear to stop us overshooting second time

final approach - decent agility and landing performance i think , quite user friendly (even a terrible approach like this can be salvaged)

 

Edited by AeroGav

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OK guys,  Christmas is approaching, so it's time to fatten up the Turkey.    Added a seventh nerv, trim flaps, extra wings, and more fuel.

https://www.dropbox.com/s/1qa991p3trpa2qm/Thanksgiving Partridge.craft?dl=0

But   I also wanted to push it to the limits, and find out what we can really do.    Ended up 

  • removing batteries  - no effect on utility
  • making the nose gear smaller -  we seem to have got away with that ,  provided it survives landing
  • removing all but one reaction wheel - this does make a real PITA to fly in orbit

 

Final tally - 

92525 kg payload
less 25kg radial decoupler (which remained attached to ore tanks, so can't be counted in mass delivered to space)

92500 kg payload to orbit

Vessel launch mass 184997kg 

50.00081% payload fraction !  

It's taken me about 8 hours to crack that milestone,  repeatedly running barely short (last flight ran out of fuel in a 91 x 77km orbit) with 45 minutes per flight, the last attempt using every trick i could think of (rolling down the first half of the runway in dry power to save fuel ), so this definitely counts as a stunt rather than a practical proposition.    Put reaction wheels back and decent sized landing gear back on it and you'd have a nice little lifter though.

 

I'm burned out with this one,  might be a day or two before i can be bothered to fly the landing and definitely will not be shooting for over 50%.      Ideas for getting even more payload 

-  xenon tanks instead of ore - probably even denser, better mass/drag ratio? 

- fairing instead of mk3 cargo bay?

- just carry the payload externally.    2.5m parts have good drag characteristics,  you'll get much better mass/drag by not wrapping it in a heavy, draggy mk3 cargo bay

- bring some oxidizer ! maybe

- if not going fully re-use, then dump the jet engines after flameout

Edited by AeroGav

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@AeroGav I won't be able to put the new one up on the board yet until you show the fact that you've landed it on the runway successfully. But con FUGGIN grats on the 50% mark :)

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3 minutes ago, ATEC said:

@AeroGav I won't be able to put the new one up on the board yet until you show the fact that you've landed it on the runway successfully. But con FUGGIN grats on the 50% mark :)

What's the odds that the small size landing gears on the nose blow up on touchdown?

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mk1-1-0.jpg

I think I can claim 25% for non-recoverable rocketry. Small gallery and craft file -> here <-.

ETA: takeoff mass 43.165, payload is a nice round 11t.

Edited by Laie

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It lands !   

The game crashed when i shot the first vid, so  i started saving every 5 minutes on attempt 2.   This is sped up 2x.

Save scummed twice  - as i was descending mach 5 over space centre continent,  i wasn't aggressive enough trying to bleed speed, did a horizontal 180 which took my miles out over the sea.     Probably had enough fuel and glide range to get back, but it would have been a 20 minute cruise,  so redid that bit with an inverted half loop.     

After that we had a final touchdown blooper  -   had no idea what the approach speed was (having not flown it empty or landed this version of the plane before) ended up floating down the whole runway, deciding to go around (retracted the gear) just as airspeed finally ran out and before  the engines could spool up.   Ended up flopping down wheels up on the last few metres of runway then skidding off the end.  Not much damage apart from the lower nuke pair getting crushed and spreading radioactive stuff.

So we savescummed short finals, using the cargo bay as an airbrake to scrub off a bit more speed.

 

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Maybe if someone tried combining tech from my vessel with this guy's approach to delivering an orange tank -

https://kerbalx.com/SpaceAgeDreamer/RX-MK2V7R2

before flight - 

zqewD0h.png

after flight 

Gid0fog.png

props to @spaceagedreamer !

-  or a smaller version of the above, carrying xenon tanks to orbit.  That's almost practical, since you can't mine xenon..

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Rocket only: 26.5% -- 11,264kg/42,564kg

This is an almost complete copy of Laie's craft, tuned a little so that the payload fraction is improved by 1%.

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2 hours ago, SanderB said:

Rocket only: 26.5% -- 11,264kg/42,564kg

This is an almost complete copy of Laie's craft, tuned a little so that the payload fraction is improved by 1%.

That rocket has impressive length,  I must say.

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3mCandle-1.jpg

117t payload, 442t rocket, for another 26.5% payload fraction. Craft file.

As it is, get it to a ~50sec time-to-apoapsis on the first stage and then just stick to surface prograde. There's still room for improvement so this isn't a proper entry. I'm just leaving this here because a) I gotta go and b) I totally expect @SanderB to eke out another half percent in any case, so why bother?

14 hours ago, AeroGav said:

That rocket has impressive length,  I must say.

In german the saying is "länge läuft". Could be translated as "length runs well" or so, I'm certain english-speaking engineers have come up with a similar phrase.

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Just a question for you guys: 
If someone beats his own fraction, should he get another place on the board or just 1 place on the board and a place on a sub-board including all the beaten times?

Laie, and SanderB: Your crafts are on there, beaten fractions on the hidden scoreboard

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I've slightly exceeded Laie's exceptation and got to 27.2% (120,875/444,928) with a slightly modified version.

I expect that 0.2% perhaps 0.3% can be added by adding more to the payload, staging as efficiently as a KOS script would and not exceeding the ap by more than 1  meter.

Craft file. Flying instructions: Turn on SAS, stage, SAS prograde at 110m/s airspeed. (stage twice whenever an engine cuts out.) Once pitch is less than 10 degrees, maintain pitch at 10 deg. When AP is 90km, cut off engines. Circularize at AP.

I think more efficiency might also be achieved by not forcing pitch to be no less than 10 deg while thrusting but I can't be bother to try.

Edited by SanderB

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6 hours ago, ATEC said:

Just a question for you guys: 
If someone beats his own fraction, should he get another place on the board or just 1 place on the board and a place on a sub-board including all the beaten times?

Laie, and SanderB: Your crafts are on there, beaten fractions on the hidden scoreboard

I'd say that depends. Slight variations on the same topic are probably not worthwhile, but wholly different designs may be. Threads like this can be a great educational resource, but to that end you should probably point out noteworthy entries. Like, well-documented "how to" ascents or designs that are somewhat unusual but easy to understand (I'd put my first entry with it's low-power 2nd stage in that category). The most teachable ones are not necessarily those that score the best.

4 hours ago, SanderB said:

I've slightly exceeded Laie's exceptation and got to 27.2% (120,875/444,928) with a slightly modified version.

I'm impressed but (begging your pardon) not really surprised.

However, over the day I figured that there's room for considerable improvement: the last stage is quite overpowered while the first leaves much to be desired. Also, that the KR-2L went unused at takeoff bothered me. It's surface TWR may be bad, yet utilizing it to some degree just *had* to be better than carrying it aloft as payload.

So, what if I crank up the ballast in order to provide a proper burden for the last stage? And use two strap-on Mammoth boosters rather than one below the inert Rhino? And the answer was, it doesn't work well. I needed an even higher surface TWR to get the KR-2L to 10km quickly. That ultimatley led to this design:

candle-2-15.jpg

Gallery and craft file

The LFBs may also not have the best ISP, but I consider them more as self-propelled fuel tanks: most of the fuel they carry is burned in the more efficient Mammoth engines. Adding them required an even heavier payload to maintain the target fraction, but as it turned out that didn't hamper the upper stages at all.

Two sparks for control because #lolnogimbal Aerospikes.

With that thing, I managed 186.2/674.73 -> 27.6%

Not that I expect that score to stand long. I have an inkling that more Mammoths and Aerospikes would do even better. Maybe even a hint of nukes -- if one keeps them running all the way from the ground up, they have to be good for something. You need basically no thrust for the last 200m/s, so they could be the last candle burning.

Edited by Laie

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Booyah, 27.336%
:cool:

https://imgur.com/a/bu28F

I livestreamed this too, so after it's processing you'll have a video. Took me long enough, this was hard.

Addendum, just saw how this architecture falls a tad short, no pun intended, I have some room for improvement, I'll be revisiting this this evening.

Edited by Fauble2000

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Lots of very long and thin mk1 sized rockets out there, but do people know that 2.5m fuel tanks have the best capacity / drag ratio of all ?   Maybe an orange tank based lifter, with a 2.5m tricoupler and some aerospikes/vectors ?

 

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