ATEC

Stock Payload Fraction Challenge RE-BOOT

83 posts in this topic

@AeroGav I added you to the leaderboards! ATM Your plane is the best one in the category (duhh) and of everything that entered (wut?)

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41 minutes ago, AeroGav said:

BTW it's a bit of a weird challenge, ore is not a payload you'd normally launch out of kerbin.

The challenge rules do not stipulate anything on that regard, so it's up to the contester to decide what their payload it going to be.

My D1/D2 payload included small ore tanks, filled to 'top off' the mass when I noticed there was still margin to be gained, but it is mostly LFO and monoprop, and a fully functional orbital refueling station.

Besides, one could make a case for ore pods being a very dense form of fuel for a refuelable interplanetary vehicle, if one includes an ISRU in the configuration...

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On 4/23/2017 at 5:38 PM, gchristopher said:

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.

Ouch, I didn't realize the previous iteration was considered so influential. Sorry I had to discontinue administering it.

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10 minutes ago, ATEC said:

@AeroGav I added you to the leaderboards! ATM Your plane is the best one in the category (duhh) and of everything that entered (wut?)

You forgot to round it up to two decimals, which is in his favour. And the SSTO spaceplanes are still ahead.

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Don't I get 10 points for the landing?

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I got over 22.34% with this rocket:

fIFEiNK.png

Quite surprised that high TWR can greatly improve fuel economy!

I'll post this as an entry after adding wings to the second stage.

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20 hours ago, AeroGav said:

BTW it's a bit of a weird challenge, ore is not a payload you'd normally launch out of kerbin.

Used on my part entirely due to superior density; it's hard to cram much more than 40ton into a single cargo bay if using anything else unless you part-clip to an extreme degree. The Kerbotruck was originally designed to haul Science labs and orange LFO tanks...which, once you add the batteries/RCS/docking ports/etc, tend to come out at about forty ton or less.

gkskMv8.jpg

In ye olden days, there was a mod that was nothing but a test weight, with tweakable size and mass. Very handy for testing lifters, and made for a pretty good deadfall bomb as well... :)

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I was able to fly a rip-off of Nefrum's Stingray Mk14 (rebuilt to be visually similar) to a 75x75 orbit and return, leaving a 48% payload fraction in orbit. That's not my design, so not really fair to enter here. Plus, no autopilot assist is a non-starter for KSP-playing these days. I put in enough hundreds of missions doing the "carefully tap a key to get just the right analog control" routine (wow, in 2014) that flying without an autopilot isn't worth the frustration. That's a level of masochism that's happily left in the past. I sympathize with those who haven't hit that breaking point. I held out against using Mechjeb for an awfully long time, too. 

That test flight was quite a bit lower than the 58% that Nefrum posted in 1.0.5. I can't really tell how much of that is due to aero changes, engine changes, or my own semi-ignorant understanding of the ascent profile. Still, me getting 48% to 75x75 that seems to indicate that someone actually competent can probably get 50% to 100x100! That's encouraging, because it hopefully puts 25%-30% into the range of payload fractions for routine, not-pushing-the-envelope flights. 

Thank again or reviving this, @ATEC! I hope people keep posting and filling out the thread with attempts!

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Here's my entry - a sub-100T rocket-only disposable launch vehicle. Running Vectors on the first stage is, of course, not the most economical choice for a disposable launch vehicle, and a Boar booster with two Thuds for thrust vector control can be substituted to save the better part of 30k funds while sacrificing less than 1% mass fraction. It then becomes a very economical disposable mid-game career booster for on-orbit refueling, though less RCS/batteries and more fuel would make it better for the job.

The there are several tricks I used to push the mass fraction as far as it would go on this vehicle. Firstly both the Boar+2xThuds and twin Vectors give approximately 2-2.2:1 TWR at takeoff, allowing me to start the gravity turn almost immediately; In fact, the rocket sits on the pad with ~3* tilt in the clamps.. This reduces gravity losses by about 350-450m/s over a more sedate 1.2:1 TWR. Secondly, since the payload makes up such a large fraction of the rocket's mass, the poodle is the best choice for the second stage engine, whereas a lighter payload rocket might use a Terrier or even a Spark engine to get better delta-vee. By starting ascent with such a high TWR first stage and releasing it low in the atmosphere at high velocity, the long-burn second stage has plenty of time to expend its fuel and bring the payload into orbit. Third, the payload is as aerodynamic as possible - even with a very aggressive gravity turn drag only rises slightly over 2m/s^2 before beginning to fall again. Finally, by using the fuel tank adapter on the second stage, I am able to use 1.25m tanks to fine tune the delta-vee of the stage and use the 1.25m decoupler, which eeks out a little bit more delta-vee than the much heavier 2.5m decoupler even though the conical tank is 30kg heavier than its cylindrical counterpart (50kg + 30kg vs 400kg); those extra 320kg can go straight to payload instead.

Launch Mass is 93,615kg and payload to orbit is 23,420kg making for a mass fraction of 25.017%. I leave MechJeb's Smart ASS up the whole time to show that I am not using it but only the data readouts. If I need to I will install KER and fly the mission again with that instead.

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Posted (edited)

Completed the 140t lifter. Had to add some fuel on the first stage for the wings and safety margin.

140.1t to LKO under 300/t, Payload fraction 21.65%

EDIT: Craft file - flight instruction is both in the craft description and the album.

Edited by Abastro

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@Abastro and @SRFirefox i am on vacation in turkey so i Will adem thrm to the leaderboard once i get back to mah laptop

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@SRFirefox For what category is it?
 

@Abastro I added you to the leaderboards! 

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On 4/25/2017 at 9:00 AM, Red Iron Crown said:

Ouch, I didn't realize the previous iteration was considered so influential. Sorry I had to discontinue administering it.

Well, you are the coolest moderator around :)

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Hol' up, the part clipping rule.

Are there NO exceptions? Like wing clipping for design?

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26,55% 

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Posted (edited)

Uh-oh @Nefrums! That's 29 hundredths of a percent less than your 1.0.5 record!

edit: Oh wait. This challenge is 100x100 instead of 70x70 for the old challenge. So this run is actually significantly better.

I think the spaceplane percents in the OP are off still. There's still the extra 10 added to the payload fraction reported as the percentage. 

Edited by gchristopher

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Posted (edited)

@gchristopher owhhhhhh... UR RIGHT!!!

 @Nefrums Nice to see that you tried the new reboot too! I will add it to the leaderboards!

 @SpaceplaneAddict Part-clipping will only be allowed if it will be used as a dead weight and CAN NOT do anything functional (SO NO ENGINES OR FUEL_STUFFS)

Edited by ATEC

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Posted (edited)

@Nefrums  I added you to the leaderboards!!!!

@gchristopher I edited the spaceplane thingy

 

Edited by ATEC

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Posted (edited)

This isn't an official entry since there is part clipping (mostly for aesthetics), but I'll post it anyway. I was pleasantly surprised to see that it's somewhat on par with what others are posting. I remember reading posts (from @GoSlash27 in particular iirc) that Mk3 spaceplanes can be capable of >50%, although those may have been old posts.

It's meant to be interplanetary with lighter payloads.

Payload fraction of 35.96% (must be something to do with economies of scale)

P.S.

Consider this a not so subtle callout, Slashy. I wanna see your entry to this challenge.

Edited by NoobTool
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13 hours ago, NoobTool said:

Consider this a not so subtle callout, Slashy. I wanna see your entry to this challenge.

NoobTool,

 Sorry, but I'm on hiatus from KSP at the moment. I've been out terrorizing the countryside with the Rubber Knife Gang; my scooter club. I have a vertical lifter design that I believe can break 30% in this challenge, but I'll have to find the time to modify it.

Best,
-Slashy

 

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1 hour ago, GoSlash27 said:

I've been out terrorizing the countryside with the Rubber Knife Gang; my scooter club.

They sound a fearsome lot. We'll anxiously await your return. Until then, enjoy the frightened screams and angry fist-shaking of little old ladies. :D

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26 minutes ago, NoobTool said:

Until then, enjoy the frightened screams and angry fist-shaking of little old ladies. :D

..that are riding on the backseats of the scooters? :D

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brOr0rU.png

Clipped a nuclear one in a bit to look a lil' nice. Is it acceptable?

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