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Lowest Cost to Orbit


Aiden.J
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Hello! Today, your challenge is to achieve orbit with the most minimal cost to weight ratio.

RULES- 

NO CHEATING

No cheat menu (Alt-f12 menu)

No mods that add parts/change game mechanics (MechJeb and KER and the such are allowed)

No altering game files

Minimal part clipping (the screenshot of the rocket in the VAB/SPH must show the final design)

To find cost/weight ratio, simply divide cost by weight (in kg, not tons). (If the delta-v is below 3400 m/s, i will also add additional points where necessary, but i haven't figured out the formula :/)

PARAMETERS-

Orbit must be roughly equitorial, prograde respecting Kerbin's rotation, as well as have a periapsis of 100km+

To enter, include screenshots of the rocket/SSTO in the VAB/SPH, a screenshot of the rocket in suborbital flight in the atmosphere, as well as a screenshot of the rocket in it's final orbit.

*ALL SCREENSHOTS MUST INCLUDE KERBAL ENGINEER, OR SOMETHING THAT SHOWS WEIGHT, DELTA-V, AND OTHER PROPERTIES OF THE ROCKET*

Make sure to include a craft file, for others to reference, and I to judge. 

If you do not have access to KER or MechJeb, but wish to enter, please include a video of the launch.

Lastly, during orbit, please include a picture of the Map screen, showing the Periapsis and Apoapsis of the orbit, or have KER or MechJeb displaying the characteristics of the orbit.

MISCELLANEOUS-

MechJeb Link (compatible with 1.3.1)- https://www.curseforge.com/kerbal/ksp-mods/mechjeb

KER Link (should also be compatible with 1.3.1)- https://kerbal.curseforge.com/projects/kerbal-engineer-redu

Hard Mode- SSTO

Another Hard Mode- SRBs

Super Mode- Impress Me

I will list rankings in respective categories, but do not expect frequent updates. 

If i make any mistakes, or you'd like to suggest changes, please leave a comment.

The competition officially ends Sunday, the 28th of January, 2018, though i may update the rankings if i see a truly amazing rocket.

A payload submission is accepted, though not listed in this challenge.

REMINDERS-

Don't forget to check your staging

HAVE FUN

Leaderboards-

Payload (SSTO)- 

1. funk (1.737 per kg)

2. Wanderfound (2.330 √ per kg)

Payload (Staged Rocket)-

1.

Normal-

1.

Hard (SSTO)-

1.

Hard (SRB)-

1.

Super Hard- 

1. sevenperforce (0.164 per kg) (SSTO and SRBs)

Edited by Aiden.J
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Lowest cost to launch weigh ratio, for a 100km-orbit capable vehicle?

Hokay...

.

.

.

Looks up single propulsive part with lowest cost per kg, assemble 17000 of them.....

.

.

never mind.. look up **any** item with lowest cost/kg ratio, assemble 17000 of them. then decoupler on top and small efficient rocket on that.

 

Edited by MarvinKitFox
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Ok! In the mean time, i'll begin my own attempt :/. Also, i made changes to the "formula" to calculate score. Weight was undefined, it is kilograms now, not tons. Sorry for the inconvenience. 

Edited by Aiden.J
stuff
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36 minutes ago, Aiden.J said:

Ok! In the mean time, i'll begin my own attempt :/. Also, i made changes to the "formula" to calculate score. Weight was undefined, it is kilograms now, not tons. Sorry for the inconvenience. 

All right, got it. 320x101 km. Slightly cheaper per kilogram than before.

Now to make an album and get it uploaded.

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8sEzEN1.png

 

fUl9HNy.png

 

7eUSMPS.png

 

GZMOmYi.png

 

8nyCcjR.png

 

Album at https://imgur.com/a/0hoa1

All recovered apart from fuel and payload. Payload mass = 58,550kg. Fuel expended = 6,638LF & 3,876O.

Total expense = 6008.08. Cost per kg = 0.1026

Craft file at https://www.dropbox.com/s/61hka91j7ja31uc/Lifta.craft?dl=0

Edited by Wanderfound
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Assuming the target cost/weight ratio is about what's on the launchpad...

Here's my successful entry.

SSTOSRB only (Hard Mode x2), 0.164 kerbucks/kg on the launchpad.

screenshot0.png

As you can see, all the thrust limiters are set very carefully to get a thrust and isp curve matching the ideal ascent profile all the way from launch to circularization. I've got a handful of Sepratrons for final orbital adjustment.

From there, it was a lot of trial-and-error to get the right ascent. There is very very little control authority on this, so it was a challenge.

Full album:

Spoiler

 

Lifting off:

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screenshot27.png

Just made it!

screenshot33.png

Edited by sevenperforce
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6 hours ago, sevenperforce said:

Assuming the target cost/weight ratio is about what's on the launchpad...

Here's my successful entry.

SSTOSRB only (Hard Mode x2), 0.164 kerbucks/kg on the launchpad.

screenshot0.png

As you can see, all the thrust limiters are set very carefully to get a thrust and isp curve matching the ideal ascent profile all the way from launch to circularization. I've got a handful of Sepratrons for final orbital adjustment.

From there, it was a lot of trial-and-error to get the right ascent. There is very very little control authority on this, so it was a challenge.

Full album:

  Reveal hidden contents

 

Lifting off:

screenshot01.png
screenshot02.png
screenshot03.png
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screenshot18.png

screenshot20.png
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screenshot27.png

Just made it!

screenshot33.png

Wow! You really did it, good job. I'll add you under the super hard mode list. Thanks for the submission! Craft file? It isn't necessary, but it's for example. If anyone uses anything similar (or modifies your craft file and submits it for the challenge), just a little better, i won't add the cheater's name to the leaderboard.

Edited by Aiden.J
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39 minutes ago, GoSlash27 said:

Aiden.J,
 Wait... so the scoring is by how much the rocket weighs on the pad, not the payload it puts in orbit?

Best,
-Slashy

That's how I originally read the rules, which is why I jumped at making an SRB SSTO, but it might be a more interesting challenge to measure cost per kg of payload.

Of course, then you have to exclude the cost of the payload, and you have to define what counts as payload, and you have to decide how to handle reusability. If you say recovered parts don't count toward your launch cost, then the only way to be competitive is to use a HTHL SSTO or other fully-reusable solution, and it ends up being a "lowest fuel cost per kilogram of payload" challenge, which is different still. If you say recovered parts DO count toward launch cost, then no one will bother with recoverability.

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1 minute ago, sevenperforce said:

That's how I originally read the rules, which is why I jumped at making an SRB SSTO, but it might be a more interesting challenge to measure cost per kg of payload.

 That clearly makes the most sense. SRBs are both cheap and heavy.

1 minute ago, sevenperforce said:

Of course, then you have to exclude the cost of the payload, and you have to define what counts as payload, and you have to decide how to handle reusability. If you say recovered parts don't count toward your launch cost, then the only way to be competitive is to use a HTHL SSTO or other fully-reusable solution, and it ends up being a "lowest fuel cost per kilogram of payload" challenge, which is different still. If you say recovered parts DO count toward launch cost, then no one will bother with recoverability.

We've had several iterations of challenges in the past for cost per tonne of payload to orbit. Disposables, recoverables, and SSTOs. Not actually difficult to sort it out.
 Just wondering where the challenge is if scoring is done this way, and what point there is to it (if any).

Best,
-Slashy

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2 hours ago, GoSlash27 said:

Just wondering where the challenge is if scoring is done this way, and what point there is to it (if any).

IDK Man, i just had an idea. I don't really get the scoring either, and want to incorporate the cost more, but can't figure out a formula that effectively does that. I said whatever came into my head first, and just saying cost alone kinda defeats the purpose because the purpose is to be creative, and with cost alone there is only one winner, discouraging creativity. If you have any idea for the scoring formula, spill em' out, i'd love to hear. In the mean time, i'll think of my own. I also changed the different categories to separate payloads from actual rocket design on the launchpad, because i didn't really define it (though saying rocket a few times instead of payload in orbit may convey my true intentions). TO answer your original question, it was originally intended to just be rocket weight on the launchpad, but with a recent payload submission by Wanderfound, i changed the rules to include it. Sorry for inconvenience.

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Aiden.J,

 No worries, it's your challenge. :)

The way we've done it in the past is like this: (Launch cost-payload cost-recovered parts)/ payload mass delivered in orbit. "Payload" is defined as a completely inert mass, unable to provide assistance in its own delivery. It provides no fuel*, thrust, RW torque, electricity, or guidance.

*For fuel delivery to orbit, we would have to demonstrate docking and delivery, then divide the cost by the fuel mass delivered. 

HTHs,
-Slashy

 

Edited by GoSlash27
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One of the problems with the formula above is that it means the only way to be competitive is to use recoverable hardware. In order to discourage this, and even the playing field for those who want to go expendable, you can actually require multiple launches for amortization of vehicle cost. So you don't get to deduct the cost of your recoverable hardware, but you can reuse it. You can mandate something like "no more than 3 flights of the same hardware".

Still skews toward SSTOs, but more realistically.

For example, I have a SpaceX-style reusable booster design that I could launch once and reuse twice, dropping a new expendable upper stage and payload on it each time. Because bipropellant rocket parts are much cheaper than HTHL SSTO parts like the RAPIER, I could still potentially come in cheaper than a fully-recoverable SSTO, amortized over three launches.

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3 hours ago, sevenperforce said:

One of the problems with the formula above is that it means the only way to be competitive is to use recoverable hardware.

sevenperforce,

 Not necessarily. Previous challenges focused on different mission modes, but there's no reason why the challenge can't have separate leaderboards. One for SSTOs, another for partially recoverable, another for disposable, etc.
 Even though SSTO space planes are clearly the cheapest way to orbit payload, there's still a lot of advantage to developing cheap disposable and partially- recoverable lifters.

The down side (at least as I see it) is that all of these challenges have been done before.

Best,
-Slashy

Edited by GoSlash27
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11 hours ago, GoSlash27 said:

sevenperforce,

 Not necessarily. Previous challenges focused on different mission modes, but there's no reason why the challenge can't have separate leaderboards. One for SSTOs, another for partially recoverable, another for disposable, etc.
 Even though SSTO space planes are clearly the cheapest way to orbit payload, there's still a lot of advantage to developing cheap disposable and partially- recoverable lifters.

The down side (at least as I see it) is that all of these challenges have been done before.

Best,
-Slashy

Yes, separate leaderboards are certainly possible. But (and this is entirely beside the point of the current thread) I think one of the key features of a really good challenge is that scoring is balanced enough that all participants can enter under the same leaderboard. If you can structure the scoring in such a way that airbreathers and semi-reusable launchers and SSTOs are all vying for first place on a relatively even playing field, you've got yourself a really good challenge.

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It's been a long time that I partizipated in an efficiency challenge and some similar craft have been done before. Anyway here is my entry:

https://imgur.com/a/YCjLO

payload mass: 46250kg

Costs for fuel: 4420 credits

costs per mass: 0.0956 credits/kg

This challenge has a lot of potential, but given the fact, that I squeezed in as much mass (Ore) into the cargobay as possible and optimized the fuel load, it's kinda irrelevant for usual gameplay. Maybe a useful payload like the Mulletdyne fuel tank from the Shuttle Challenge makes more sense.

craftfile: https://drive.google.com/open?id=15iTKH8dBW2G6KmG0sPBLUjEmC96dBizV

Edited by funk
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15 hours ago, funk said:

payload mass: 46250kg

Costs for fuel: 4420 credits

costs per mass: 0.0956 credits/kg

Son, what? Its the total cost of everything, not just fuel, divided by the weight of the payload. I did the math and you got a score of 1.737 kerbucks/kg, not 0.0956 kerbucks/kg. Great submission though, i'll update the leaderboards.

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13 hours ago, Aiden.J said:

Son, what? Its the total cost of everything, not just fuel, divided by the weight of the payload. I did the math and you got a score of 1.737 kerbucks/kg, not 0.0956 kerbucks/kg. Great submission though, i'll update the leaderboards.

Ehm... it's a SSTO every cost except fuel will be refunded when you land at KSC... am I misunderstanding this somehow? cause it's basically the same what Wanderfound did.

Edited by funk
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