Stock Payload Fraction Challenge: 1.0.5 Edition

[Nao]

Not a big improvement above my direct competitor cybersol but i wanted to post something on the board . Rocket only three stage launcher, with 26,29% fraction. (100t / 380,37t) (last seconds of the video shows both values) 3057m/s dV vac with ~13m/s left in 70.5x70.5 orbit

Don't like the idea about decouplers and docking ports to stay on launcher, its very easy to just use the 0.5m decoupler and strut it up like i did in the vid, the effect on mass is minimal (like when decoupler/Dport was part of payload) but it looks silly. Also not sure if the combined "payload + last stage" fairing actually helped here or was just a dead weight hehe , at least this kind of design thou helps stability quite nicely (for normal rockets) so maybe it will catch on.

In terms of TWR it looks like the KR-1x2 is the best engine available but i wonder if the increased ISP (+15) of KS-25x4 could make enough of a difference to overcome weight penalty. Welp, at least LV-N is probably out of the picture, as it barely can lift itself up in this patch, so no long high angle burns to get the last inch of performance out of it in the last stage.

[Red Iron Crown]

Great entry, Nao, I've added you to the leaderboard.

I see what you're saying about the decoupler/docking port, but my intention is to have designs that are actually useful as launchers for other payloads. I'll leave the rule be, if people want to chase those last few kg by using undersized parts that's not the end of the world.

[maccollo]

Launcher mass 1002.25 tonnes

Payload mass: 276.45 tonnes

payload mass fraction: 27.583%

The current name of the rocket is just "silly efficient rockets". Been playing with RSS for quite a while now so that colors my perception a bit obviously, but I remember when I complained about being able to SSTO 14% with the new engines back when they were added.

Now when the delta V requirements are this low I'm not actually sure serial staging is even worth it at all for LKO insertions. In fact, since the monetary costs have been rebalanced so that fuel is cheap and engines are expensive it seems serial staged rockets are actually less cost effective than SSTO rockets? Cross feed comes out on top but the benefit is far lower than before.

Anyway, video!

[Radam]

Drag has changed in 1.01, so most of high twr rockets will be a hit by that.

[maccollo]

Drag has changed in 1.01, so most of high twr rockets will be a hit by that.

Welp... I guess that invalidates my entry.

I had forgotten to download it, and now my rocket is about 150 m/s short of orbit.

[Maelstrom Vortex]

Drag has changed in 1.01, so most of high twr rockets will be a hit by that.

Just hoping that doesn't kill my space train as well.

[Red Iron Crown]

That's a fine entry maccollo, you're on the board as the top closed-cyle rocket. Great video, too! One quick question, was that in 1.0 or 1.0.1 or 1.0.2?

I've added the version number for entries so we can see if the patch substantially affects things. I'd ask that any new entries specify the KSP version as well.

[KerikBalm]

I think 1.01+ 1.02 killed my largest lifter... which was already marginal and already needed to climb then dive to past mach 1.

I haven't even tried to fly it post 1.01

My older, easier to get to orbit design... used to be able to power through mach 1 in a climb, it had 12 rapiers....

I couldn't get it past mach 1... I tried climbing, and diving, but then I'd drop below mach 1 before I could start climbing again... wasn't working.

So, I just slapped an extra pair of rapiers on each wing 16 rapiers instead of 12, now it can level off and power through mach 1 (or even do it in a very shallow climb).

So.. I just crammed 40.88 tons into the mk3 cargo bay, and relased them into 75x73 orbit from a craft weighing 202.87 tons on the runway... a dismal 20.15% payload fraction.

But I got into orbit with 1604 LF and 1786 Ox... which is 16.95 tons of spare fuel

(also: 220 monoprop if you're counting)

So that gives theoretical payload of 57.83/ 202.87 = 28.5%... still pretty bad.

Of course, I don't know how one would cram that much into a mk3 bay (I could extend the bay)... so if I just remove the un-needed fuel at the start:

40.88/ (202.87-16.95) = 22% payload fraction.

At least on this flight, its climb rate was good, there were no tricks to getting past mach 1, there were no overheating issues or poor TWR...

It was easy to get the payload to orbit.

I'm expecting the best payload fractions for 1.02 to be in the 30-40% range.... more rapier dry mass, more liquid fuel needed.

-I'm still not sure if I should use the closed cycle of the rapiers, or the KR-2L. Its temping to replace the KR-2L with a LV-N pair... run with excessive LF, and then run the rapiers until oxidizer runs out - then I won't have to get the LF:Ox ratio very precise.

[mightyhuhn]

both the struggle and testrocket 1.1 can't reach space anymore they can't even get close to it now.

[SanderB]

With 1.0.2 my Efficiency Lifter 01 is down to 19.11%

[KerikBalm]

Well, using a new spaceplane design, I jsut achieve a theoretical 35.4%.... counting all the fuel left over when I got into orbit

[SanderB]

I think we need video footage to believe that. Fortunately Open Source Broadcasting software is free and high quality.

[maccollo]

That's a fine entry maccollo, you're on the board as the top closed-cyle rocket. Great video, too! One quick question, was that in 1.0 or 1.0.1 or 1.0.2?

I've added the version number for entries so we can see if the patch substantially affects things. I'd ask that any new entries specify the KSP version as well.

That was with 1.0.

Redesigned the rocket for 1.02 and managed to get a payload fraction of 25.4453% 276 tonnes of payload, 1084.68 on the pad. I had about 70 m/s left so it should still be possible to reach 26%

[Red Iron Crown]

Looks like your orbit was a bit larger than required, too, maccollo, could probably squeak a tiny bit more out.

I think I'll start a new leaderboard and close the challenge to 1.0 entries. Off to update the OP!

[KerikBalm]

I'll be putting picture later tonight (GF comes over soon), but I replicated my feat,

With a 382.9 ton craft, I put a 117.29 ton payload into orbit, with 540 ox and 3439 LF left over

This suggests with a denser payload, I could get a 35.83% payload fraction (still havent tested the reentry, should be fully reusable)

What I demonstrated was a 30.63% payload.

The first time, I used 3 LV-Ns during the ascent, and subtracted them from the payload's mass. Their thrust was so weak, and the craft so massive, that i tried it again without using them at all, and the result was basically the same... a little bit more total fuel used, but then I was able to keep the LV-Ns as part of the payload.

I didn't level off quite enough at high altitude this time, and only reached 1285 m/s on jets, instead of 1320 as before.

I was intending for it to be a 2 stage design, with the Rapiers section switching to closed cycle and boosting it suborbital, but in space (with LF left over to fly back to KSC), while the next stage (couldn't decide between a KR-2L or a triple LV-N cluster) boosted the payload to orbit.

The orbital insertion stage is in two pieces, with the payload sitting between two large docking ports... the front section of the insertion stage has a heat shield, while the rear has the engines, parachutes, and stabilizing fins (so it would deorbit near KSC).

In the end the just stage can just go to orbit, and the orbital insertion stage is unused and counted as payload.

I'm having trouble finding a good place to stage to make a reusable 2 stage spaceplane with a better mass fraction than a single stage one

[Slugy]

As we now have 1.02 here is a super simple 2 stage one (Mammoth and Skipper).

Mechjeb used for consistency, until I get the hang of being reasonably efficient myself

Using the built in numbers it's 283.97 on the pad, 62.4 payload for 21.974% - probably 22% with more ascent tweaking.

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[Red Iron Crown]

Thanks for your entry, Slugy, I've added it to the leaderboard. Did you really go through 22 iterations? If so that's some admirable perseverance.

[Slugy]

Thanks for your entry, Slugy, I've added it to the leaderboard. Did you really go through 22 iterations? If so that's some admirable perseverance.

lol no - it got a name when I saw that was about what it would lift. Only alterations from 1st build was another small fuel tank and then taking some ore out a couple of times.

Now, as to the number of launches to find a decent ascent profile - 22 may be about right ...

Might do something more complex tomorrow

[KerikBalm]

Starting mass: 381.0

Orbit achieved, much higher than needed (Ap was over 90... a consequence of the long burn time using the LV-Ns... had to burn nearly continuously towards Ap to get my PE above the atmosphere:

I notice that one I had stage only clicked... I was keeping an eye on my resources, how much LF I'd have left if I used all the oxidizer... etc...

Here's the same amount of fuel, showing everything, after decoupling the payload:

Payload released, LV-N cluster dropped:

Payload Mass: 126.04

Start mass: 381.0

Payload mass: 126.04

126.04/381.0 = 33.08%

Remaining fuel: 1987 LF, 1502

In theory, if this was removed and added to the payload (ie, use a denser payload like ore cans or something), it would add another 17.45 tons

143.49/381.0 = 37.66% payload fraction -> in theory

More conservatively... If I just removed that much from the craft to start with...

126.04/ (381.0-17.45) = 34.67%

And that should leave a good margin of error, as I'd then save the fuel that was used to lift that fuel up.

Anyway... 33.08% demonstrated.... It shouldn't stand as a record, because I've just shown that >37% is possible with nuStock aero 1.02

[Maelstrom Vortex]

So, Red Iron Crown, the update nerfed my original design, but I have found a way to fix. I'll be trying for an entry tonight once I make some tweaks to get TWR up.

[Red Iron Crown]

KerikBalm. it's demonstrated that makes a record. That plane is awesome, it's more like a small formation of planes carrying one payload. Did you have to limit the thrust on the LV-Ns to keep them from overheating? Great entry, I've added you to the top of the board.

Maelstrom, great, it will be interesting to see how you had to change it for the update.

Edited May 2, 2015 by Red Iron Crown

[KerikBalm]

I know its demonstrated... I'm just calculating to get an idea of room for improvement. Somebody should be able to come up with something at 37% to beat mine.

I'm not doing this purely for this forum challenge... I was also trying to make a usable cargo SSTO. Next is to see how much extra volume I can put in there before drag kills it.

The heating seems to be much less of an issue in 1.02

The name is deceptive, as explained in a previous post... I had intended to do 2 stage recovery, with the LV-N stage being for circularization, and the space plane being suborbital.

And since the payload isn't allowed to have any decoupler or anything, the orbit insertion stage has to decouple from it, and cant have a heat shield on the front... so I split the orbital insertion stage in two, and the part at the front has the heat shield.

The idea would be to undock the payload, then rejoin the two 2.5 sections.

But it just SSTOs anyway... there's so much LF left in the rapier+ wing stage, I can just take everytin to orbit on the LV-Ns after cutting the rapiers.

I didn't need to throttle back the LV-Ns... 1.02 really made them viable again... I didn't have quite enough reaction wheels, some thrust vectoring on them would have improved control authority in space.

I wouldn't be discarding the LV-Ns in practice. In practice, its a single stage... so I was thinking today that I should really remove the rear fins and just redock the LV-Ns with the rapier stage. I dont need the fins and heat shield for separate re-entry of the LV-Ns... They are a remnant of the 2-stage idea, and not needed for stability (can supply screen shot of it flying without those fins.

Although, for my own use, I may keep them on - so that I can deliver a payload not to just LKO, but also send it on an escape trajectory/highl eliptical orbit - and then recover the LV-Ns after some aerobraking.

Or I may use an LV-N tug that I just refuel in orbit. I don't like the idea, for role play reasons, of repeatedly sending nuclear reactors to and from orbit. New LV-Ns wouldn't be very radioactive... ones that have run for a long time, would be quite "hot"

[Maelstrom Vortex]

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Her % may not be high, but her raw tonnage is amazing for a space plane. 50+tonnage delivered to orbit.

50 Tonnes Cargo / 246 start weight, roughly 20.54% efficiency.

BUT! She's recoverable.

Oh, forgot to mention V 1.02.

Edited May 3, 2015 by Maelstrom Vortex

[Temeter]

You don't need to include *100 into your formula, % already means 'of hundred' *nitpick*

[Red Iron Crown]

...And since the payload isn't allowed to have any decoupler or anything, the orbit insertion stage has to decouple from it, and cant have a heat shield on the front...

You could use a separator rather than a regular decoupler to solve that problem, if I'm understanding you correctly. Also, I really appreciate you sharing your design process and ascent method, really show how iterative design and testing breeds efficiency.

You don't need to include *100 into your formula, % already means 'of hundred' *nitpick*

While you are technically correct (the best kind of correct), my intention was for those less mathematically inclined players from being disheartened at calculating their payload fraction as 0.20.