Economic Fuel to Oribit

[Laie]

Not to rock the boat any further but based on those assumptions you are saying buying 2 Orange tanks of fuel for $10,000.00 each is twice as good of a deal as buying 1 orange tank for $10,000.00. The problem lies in the fact that your not exactly getting any better deal here, you're just buying in bulk. If this was a Bulk launch challenge rather than an efficiency challenge I think you'd be ok.

As I understand the OP, this is intended -- at least to a degree. Moving more stuff in one launch is supposed to give a better score even if the bigger lifter isn't quite as cost-efficient as the smaller one. That very much agrees with me; and I have an inkling that there's more people beside the OP and me who'd be willing to pay a premium if they can get their stuff done in one launch rather than three. If a good scoring system can be found, the entrants to this competition might be of interest to actual, everyday gameplay.

Maybe a poll somewhere? Ask the players how much of a premium they'd be willing to pay if they can get twice or five times as much stuff in one go. Personally, if 1 amount costs 1 money, I'd be willing to pay 5 money for 3 amount, and ten money for five amount. What kind of a formula would this be? I have no idea.

EDIT: Batz, that thing is sweet -- I especially like the contrails. Name is Puff, I presume? (That said, this thing is big enough that you should replace the rapiers with actual turbojets and one KR-2L -- the improved efficiency should more than make up for the increase in weight).

Edited August 13, 2014 by Laie

[s1l3nt_c0y0t3]

K365306.40 Total

K239167.15 Booster

K 37101.47 Bus & Nose Cone

K 1200.00 Clamps

-------------------------------

K 87837.78 Cost

6,400 Fuel / (K87,837.78 / 6,400 Fuel)

6,400 / 13.724653125

Score = 466.314

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My score would be higher if I aimed better on my reentry.

[s1l3nt_c0y0t3]

@Batz_10K Is that using part clipping on the intakes?

[ihtoit]

that is a sweet launch system. I usually don't bother with nosecones :\ call me lazy (there again when I send up an anchorage I use droppable boost stages and follow up with a laser-equipped spaceplane to clean up)

[Vector]

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Craft file:

https://dl.dropboxusercontent.com/u/25339567/KSP%20Craft%20Files/Big%2052b.craft

Cost is 8029533, nothing is recovered so that is the total cost.

Fuel + oxidizer is 218435 + 266976 = 485411

Score is 485411 / (8029533 / 485411) = 29,344.6

[Pecan]

Score is 485411 / (8029533 / 485411) = 29,344.6

Now that's kicking arse!

Proves bigger is better in this challenge, where's Whackjob?

Oh well, I've just been up all night playing with some other stuff (in KSP, of course!) and then had a play with this again. Made a fully-recoverable vehicle to put three orange tubes (also recoverable) in orbit, but it only works out at a score of 4,615 (19,200 / (79,872 / 19,200)). I was disappointed to only improve the (cost / payload) efficiency from 4.26 to 4.16.

[Vector]

I've also been working on something else, more in the spirit of the challenge, but still exploiting the rules...

One observation: rules say fuel to orbit, not fuel tank to orbit, so if you were to dock, unload the fuel, and return the tank, you might save some cost in a plausible refueling scenario.

Second observation: oxidizer is cheaper than fuel, but scored equally, so if you deliver mostly oxidizer, you can get the same fuel + oxidizer at lower cost.

Both of these mostly only matter when using a spaceplane that burns very little fuel and recovers all the parts. I've got an airhogged jet that can deliver approximately 3500 fuel + oxidizer (almost all oxidizer) to orbit, for a net cost of about 1450, but I haven't got the whole thing together yet including docking and recovery. The cost of the jet is almost 400k, but it's all recoverable except for the fuel spent and the fuel delivered. If it works, it would score in the ballpark of 7000 or so, and if I strapped 5 together it might even exceed the score of my Whackjob imitation.

I'm not sure if I will finish it, but I thought it was an interesting idea...

[Laie]

Score is 485411 / (8029533 / 485411) = 29,344.6

Now that's kicking arse!

Proves bigger is better in this challenge, where's Whackjob?

Playing other games or mending his computer or something. But size alone isn't everything, very low cost still has some effect: my lifter from here makes, let me see, 32400**2 / 19189 = 54,706. Not even 1/10th of Vectors size, but the difference in cost is 1:400.

Big SSTOs can still win over much bigger throw-away rockets, but either way, the vessels have to be big. Like, real big. He who dares the highest part count comes out as winner.

[Bothersome]

That's in impressive amount of fuel you got there. Put that in orbit and you won't have to worry about running short for a little while. Nice job.

Yes, the score rewards bigger, but someone could improve on that just a bit and beat you with efficiency. You are correct in that you could off-load the fuel into a storage tank already in space. As long as honesty is maintained, I have no problem with it. I'll go post your score.

[Pecan]

@ Vector and Laie - Yes, what we haven't seen yet are any jet-based solutions actually posted as entries, planes or not. They should use much less fuel for a given payload and, since with recovery payments that's the only thing that really costs anything, they should be very efficient.

[Laie]

@Pecan: Have you read the post I linked to, above? A stock plane of that size would be a 700-part monstrosity, and that's only the functional parts. You'd need a few struts on top of that, to hold the whole mess together. I didn't calculate it, but a halfways reasonable plane of perhaps 200-300 parts probably wouldn't be competitive under these rules.

[Pecan]

@Pecan: Have you read the post I linked to, above? A stock plane of that size would be a 700-part monstrosity, and that's only the functional parts. You'd need a few struts on top of that, to hold the whole mess together. I didn't calculate it, but a halfways reasonable plane of perhaps 200-300 parts probably wouldn't be competitive under these rules.

Yes, I read the post and even if a plane can't, in practice, compete with Vector on size it should easily be able to beat my single orange-tube payload. I'm therefore surprised we haven't seen any. Jets should make a lot of difference, I'm still unconvinced wings help much for anything except landings.

[Laie]

Jets should make a lot of difference, I'm still unconvinced wings help much for anything except landings.

Hmmm. Maybe we should take this to a thread of it's own?

If you have a look at http://ksp.schnobs.de/k-prize/, numbers 46ff are details from one excruciatingly slow ascent (I was going for maximum fuel economy). Some lingering around 30km is absolutely necessary; you can see that I'm gaining about 450m/s around there. Is that possible without wings? Whenever I tried jet-powered rockets, I had to climb-climb-climb and thus rushed past the 30km mark at much slower speeds. Then the air ran out.

[DundraL]

Is usage of FAR allowed? I definitely have a few spaceplanes that could do some damage to the leaderboard, but they certainly require FAR if they are to even be flyable... If so Ill update this into a full entry.

Also, on scoring, is the payload(fuel) considered cost? It definitely makes a difference for spaceplanes and sstos, where leveraging the efficiency side of the equation is where their points come from. In the case above, it more than doubles the cost.

Edited August 15, 2014 by DundraL

[Vector]

Jet power to orbit with very little rocket boost is definitely possible without wings, although I don't believe it's feasible without air-hogging. If TWR is greater than 1 you can adjust your attitude to fly level, no wings required. At low speed you will be mostly vertical, and at high speed you aim mostly horizontal.

But don't take my word for it, I'm working on a demonstration.

[Pecan]

Yes to both of you again - above 25km or so and into the mid-teens speed 1,300-1,900m/s wings are only good for about 5-degrees of pitch or so. No problem flying a jet ascent profile without all the mass of wings. I don't think this needs a new thread - we need some spaceplane submissions for this one :-)

@ Dundrat - yes FAR is allowed:

The rules:

1. MODS are allowed provided only the STOCK tanks and methods of propulsion are used. (No magic engines) You can use any stock method you see fit though.

[Bothersome]

Is usage of FAR allowed? I definitely have a few spaceplanes that could do some damage to the leaderboard, but they certainly require FAR if they are to even be flyable... If so Ill update this into a full entry.

Also, on scoring, is the payload(fuel) considered cost? It definitely makes a difference for spaceplanes and sstos, where leveraging the efficiency side of the equation is where their points come from. In the case above, it more than doubles the cost.

Yes I'll allow FAR but I will post a note by the score noting FAR was used. Far really changes the parameters of the game, but it would be nice to see some crafts that operate well under FAR (or NEAR). The gist of the challenge is to show our newer audience what type of crafts are feasible to get large quantities of fuel to space. This is why more is better than just economy alone. Because a newbie doesn't always know how to dock like an expert and want to avoid it as much as possible. Yet, as we seek a way to get fuel to space, we want to do it on the cheap.

[DundraL]

Well finally got back to my computer, here ya go =)

launch cost-392532

Recovered -360147.15

mission cost- 32385

Fuel to orbit-49112* this number does not include all fuel shown in orbital pic, some was kept for deorbiting etc.

Score-74,478.5

I suck at BB code so I'll just link to the pics.

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http://dundral.imgur.com/all?

Edited August 27, 2014 by DundraL

[Bothersome]

That's probably THE most impressive space fuel hauling plane I've ever seen that's used stock parts only. Great job there, I'll go post your score.

[Vector]

Finally finished docking delivery of oxidizer and full recovery, like I had talked about.

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I had to use MechJeb for the landing predictions, because without it, I can't even hit the continent. I used only the landing prediction and flew the entire mission manually. I also used MechJeb's 'prevent overheats' because I have a horrible tendency to overheat nuclear engines since there is no warning in map view.

Craft cost: 517,374

Recovered: 506,026

Net cost: 11,348

Delivered oxidizer: 37,932

Score: 37932*37932/11348 = 126,792

Powered landing with jets is tricky. I knew it would be hard but I underestimated how difficult it would be. I crashed many times before I got a successful landing.

If anyone is interested, here is the craft file. Bigger is definitely possible, but it is already a bit sluggish, so going bigger would be just more unpleasant to fly.

[Bothersome]

That's an impressive load you put up into space there. It puts you on top, even though it was for score only. Doesn't really tell us how much actual usable fuel at that cost goes into space. I guess anyone wanting to try the craft for actual work, will just have to look for themselves.

By the way, to all contestants, if you wish to update your attempt, either post a new attempt or at least a message to the thread so that I'd know your score needs updating. If you just go back and edit your attempt on some earlier page, I may never know that it was updated.

[Vector]

It is possible to calculate. Let's see..

I had another screen shot which I left out of the album because it wasn't very interesting, but it is relevant here:

This shows that at launch there was 6480 fuel and 39600 oxidizer.

37932 oxidizer was delivered

After landing, I had 973 fuel and 1032 oxidizer remaining.

So I spent 6480 - 973 = 5507 fuel and 39600 - 37932 - 1032 = 636 oxidizer.

The cost of fuel is 5184/6480 per unit

The cost of oxidizer is 1425/7920 per unit

The cost of spent fuel is 5507*5184/6480 = $4406

The cost of spent oxidizer is 636*1425/7920 = $114

The cost of delivered oxidizer is 37932*1425/7920 = $6825

The cost of spent and delivered fuel together agrees (within rounding) to the quoted total net cost of $11,348.

Now, if you were to deliver a balanced mixture of fuel + oxidizer instead of pure oxidizer, how much would you get?

Well, the mass of delivered oxidizer is 37932 units times 39.6 / 7920 tons per unit = 190 tons.

One orange tank has 14.4 tons of fuel and 17.6 tons of oxidizer for a total of 32 tons of fuel + oxidizer.

A 190 ton payload of fuel+oxidizer excluding the tanks would therefore deliver 190/32 = 5.94 orange tanks worth.

This would be 2880 * 5.94 = 17,107 units of fuel and 3520 * 5.94 = 20,909 oxidizer.

This balanced payload would be very slightly higher in terms of units of fuel+oxidizer at 38,016 (instead of 37,932). But since fuel is so much more expensive than oxidizer, the cost of the balanced payload would be much higher, at 17107*5184/6480 = $13,686 for the fuel and 20909*1425/7920 = $3762 for the oxidizer. The payload would cost $17,448 instead of $6825. The total cost of payload plus fuel spent would then be 17448 + 4406 + 114 = $21,968, which is nearly twice what I spent for the cheaper payload.

The score with the balanced payload would then be about 38,016*38,016/21,968 = 65,787 points.

This indirectly suggests that if DundraL had delivered an equivalent mass of pure oxidizer, then his score would have been even higher than mine.

[impyre]

Also consider the dead weight factor. While marginal, for large payloads it might make a difference. You could've added much more fuel for no additional tank weight penalty or tank cost, creating greater efficiency. Although with the scoring taking cost into account, I can see where the incentive is to deliver the cheaper of "fuel+oxidizer"... if the scoring had been fuel*oxidizer, it might've made more incentive to carry both... or even if the cost of payload fuel/oxidizer was subtracted from mission cost for purpose of scoring. I think the last one makes the most sense, as most of us only really care about the cost of the launching system, not the payload... as the payload just is what it is.

[Bothersome]

Vector, you never cease to impress me. You don't just post some score and say there it is, you actually explained in detail how you got there. Kudos man (or gal if that be the case). We've gotten some very interesting data points out of this challenge so far. I just hope that because the score are high already, others will still try and post a showable craft. Even if your craft won't make top scores, it could still help others in finding efficient ways to get fuel to orbit.

I was hoping that when I started the challenge, that because cheaper means higher score, that crafts of early research designs would be posted too. Not just the end of research crafts. Those would help for the early game periods.

Keep up the good work everyone.

[Wanderfound]

Okay; although the scoring is biased to bulk, I figured I'd have a go just so that the spaceplane crew weren't entirely unrepresented. Flying with FAR, of course.

My spaceplane of choice is the Kerbodyne Wedgetail:

(this is my personal model with Mechjeb and TAC-LS bits on, but you can find a version with those parts removed at http://forum.kerbalspaceprogram.com/threads/90747-Kerbodyne-SSTO-Division-Omnibus-Thread?p=1353934&viewfull=1#post1353934)

Off we go:

Shock heating on the way up:

Just after the RAPIERs switch to closed cycle:

Coasting to apoapsis:

Circularisation burn:

And we're in orbit:

Plenty of gas in the tanks:

Just kept what was in the rear bicoupler to get home:

Reentry was a little on the toasty side:

Skipping over the mountains west of KSC:

Final approach:

And back on the runway, just after using the last of the fuel:

Unfortunately, I'd been flying in sandbox mode, and hadn't realised that this meant that I got no funds screen on recovery. So, I went into my career save, took the exact same plane out on the runway, and used TAC Fuel Balancer to dump all the fuel. I also emptied the RCS tanks, although I'd actually used barely any of that. The "resources recovered" are the food/water/oxygen and waste products from TAC-LS. Anyway:

Wet cost: √149322

Recovered: √143321.7

LF delivered: 3727.9

O delivered: 4186.4

Cost: √6000.3

Score: 10438.8

Splitting the bill evenly between the LF and O portions:

Price per unit of LF: √0.8

Price per unit of O: √0.7

--

Edited to add: just saw DundraL's effort. Nicely done.

Edited August 20, 2014 by Wanderfound