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Lord of Launchers

Leathan

By Leathan
in KSP1 Challenges & Mission ideas

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Leathan

Leathan

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Posted (edited)

Lightest Launcher Challenge

Developing simple space launch systems is an easy task for advanced KSP users. Just strap some tanks, engines and boosters together and off you go. This challenge asks for more. We are looking for the man or woman capable of developing the lightest possible launcher for a given payload. This also has practical implications: a light launcher is much easier to transfer to distant worlds where it can be used in advanced interplanetary missions.

RULES:

1) The launcher must take off from Kerbin space port's runway or launchpad. The inert! payload must be injected into a circular equatorial orbit of at least 120km. The launcher must include robotic control and may include multiple stages.

2) Only stock parts from KSP 0.25 allowed. Do not use mods which change the game functionality. It is a bonus if the launcher can also be used with Ferram Aerospace enabled, but not exclusively. Kerbal Engineer is recommended.

3) In case a special launch procedure is required which deviates from a traditional gravity turn, please specify. The launch should be replicable by good KSP users with a good success rate.

Sattelite Class: min. 8 t lifting capacity

Medium Class: min. 32 t lifting capacity

Non-oxygenated Class: min 32t lifting capacity without the use of air-breathing equipment / wings

Interplanetary Class: min. 128t lifting capacity

In addition to the above four classes there will be a competition for the title Lord of Launchers.

Compete in all four classes, in each category calculate the ratio of launcher mass to overall takeoff mass including class-specific! payload.

(The Payload ratio is simply 100% minus this value and vice versa.)

Average the four percentage values. The submission with the lowest average wins.

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The winner of this challenge has the legitimate right to call himself Lord of Launchers. :cool:

SCOREBOARD

[TABLE=width: 500, align: center]

[TR]

[TD]Competition[/TD]

[TD]Winners

[/TD]

[TD]LSoLM[/TD]

[/TR]

[TR]

[TD][/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]Sattelite Class[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]1[/TD]

[TD]Jouni[/TD]

[TD]26,5%[/TD]

[/TR]

[TR]

[TD]2[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]3[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]Medium Class[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]1[/TD]

[TD]Jouni[/TD]

[TD]26.3%

[/TD]

[/TR]

[TR]

[TD]2[/TD]

[TD]HelmutK[/TD]

[TD]54.5%

[/TD]

[/TR]

[TR]

[TD]3[/TD]

[TD]Leathan[/TD]

[TD]77,8%[/TD]

[/TR]

[TR]

[TD]Non-oxygenated[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]1[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]2[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]3[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]Interplanetary Class[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]1[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]2[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]3[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]Lord of Launchers[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]1[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]2[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[TR]

[TD]3[/TD]

[TD][/TD]

[TD][/TD]

[/TR]

[/TABLE]

Edited by Leathan
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Cmdr. Arn1e

Cmdr. Arn1e

Posted
Posted

Interesting first post, good sir! But there seems to be a few things missing to make this a fully fleshed out challenge...

It is customary to show your attempts; while this is certainly a very possible challenge, it's nice to have an initial yardstick to measure our own efforts against, and some people like to set up scoreboards in advance...

Not my sort of challenge at the moment, but I'm sure you'll have plenty of contenders in no time :)

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Leathan

Leathan

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Posted (edited)

So, why not... Here is my own contribution to the "Medium Class" challenge.

Payload: 32.1t

Liftoff mass: 144,9t

Launcher share of liftoff mass: 77,8%

SBQvND7.png

I call this a hybrid launcher because it launches in a traditional fast gravity turn with the main engine on from the very beginning. I think it shuld be able to lift this mass with considerably lighter launchers, if a non-traditional ascent curve is used and sufficient lateral speed picked up before the main engine is fired. My guess for the winning entry in this category is 60% with an ascent to 20000 meters and 1500 m/s using turbojets/rapiers only.

Edited by Leathan
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Pecan

Pecan

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Posted

The traditional way to measure "the lightest possible launcher for a given payload" is the Payload Ratio. Many people will already have this figure calculated for their launch vehicles and it'll help compare results here with other threads and equations if you use that measure. For KSP rockets 10% is 'acceptable', 15% 'efficient' and 20% sometimes obtainable. Can't find the thread yet but a few people have broken the 20% barrier and you should expect several entries in that range. For jets the ratio is more like 60%, somewhat lower for spaceplanes as they have to drag wings and landing-gear with them.

Payload Ratio always was the way launch-vehicles were judged in KSP before 0.24 because mass was almost the only way to measure them. Since cost and recovery now count as well you might like to look at the other 'cost effective' launcher threads too.

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Jouni

Jouni

Posted
Posted

Here is a silly old-fashioned jet-boosted rocket. It's not fully optimized, so you can probably improve it by a few percentage points.

jet_boosted_1.jpeg

jet_boosted_2.jpeg

Payload: 8.00 tonnes

Liftoff mass: 10.88 tonnes (jet stage fuel tanks contain no oxidizer)

Launcher share of liftoff mass: 26.47%

Launch procedure is roughly the following:

  1. Crawl slowly upward.
  2. Turn to 60 degrees at 10 km.
  3. Turn to 45 degrees at 15 km.
  4. Turn to 30 degrees at 20 km.
  5. Turn to 20 degrees at 25 km.
  6. Turn to 10 degrees at 30 km.
  7. Transfer fuel from the rocket stage to the jet stage just in case.
  8. Turn to 0 degrees and reduce throttle to 1/3 at 40 km.
  9. Reduce throttle to 1/6 at 45 km.
  10. When the turbojet shuts down, transfer fuel back to the rocket stage, and drop the jet stage.

When the rocket exits the atmosphere, it should be roughly on a 80x40 km orbit with around 150 m/s of delta-v left. In my test flight, I had around 40 m/s left after reaching a 130x120 km orbit.

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Bilfr3d

Bilfr3d

Posted
Posted
Here is a silly old-fashioned jet-boosted rocket. It's not fully optimized, so you can probably improve it by a few percentage points.

In case u didn't realise, the rules say "inert" payload. if that second stage has any engines on it, your entry is not allowed. Not that i'm saying it does have one, but from the description it sort of sounds like it does.

I'll definitely be having a crack at this challenge. I have a few good ideas up my sleeve :P

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Jouni

Jouni

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Posted
In case u didn't realise, the rules say "inert" payload. if that second stage has any engines on it, your entry is not allowed. Not that i'm saying it does have one, but from the description it sort of sounds like it does.

Rockets usually have multiple stages, especially if we're interested in maximizing the payload fraction. In this case, the inert payload is the third stage: a 4.5-tonne fuel tank, a 3.4-tonne monopropellant tank, and a 0.1-tonne adapter.

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Leathan

Leathan

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Posted (edited)
Rockets usually have multiple stages, especially if we're interested in maximizing the payload fraction. In this case, the inert payload is the third stage: a 4.5-tonne fuel tank, a 3.4-tonne monopropellant tank, and a 0.1-tonne adapter.

Yes, multistage launchers are allowed and even encouraged. I will try out Jouni's design tonight, but since I think that it is legitimate I already put him on the scoreboard.

Here is an example of a non-inert (not allowed) payload: a 36t orange tank at liftoff which ends up in orbit with a remaining mass of 32t. To avoid confusion I would suggest you add a docking port at the end as part of your payload.

EDIT: I have tried out Jouni's 8t design and it took me quite a few attempts and a lot of peeking at vertical speed to fly it, but it does indeed work (sometimes).

Edited by Leathan
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Leathan

Leathan

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Hi,

Payload: 62.5t

Liftoff mass: 140.05t

Launcher share of liftoff mass: 55.37%

Very nice launcher! It puts you on top of the Medium Class Ranking as of now, but please calculate the LSoLM with the class-specific payload of 32t. If I did the maths right that is only 70,8%. Also I think just by dumping fuel or minor design modifications you could adjust your maximum payload to reach an even better score.

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Jouni

Jouni

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Posted

I made a 4x bigger version of my old rocket.

jet_boosted_3.jpeg

jet_boosted_4.jpeg

Payload: 32.00 tonnes

Liftoff mass: 43.41 tonnes

Launcher share of liftoff mass: 26.28%

This one is easier to fly than the small version, and the margins are higher. The launch procedure is the same, but there's no need to transfer fuel from the rocket stage to the jet stages. There are four jet stages similar to the jet stage of the smaller rocket, attached to the rocket stage with radial decouplers. The rocket stage uses heavier and more efficient 48-7S engines, and there was also room for reaction wheels, as I didn't need four probe cores.

Construction note: I built one jet stage first, attaching the engine before any intakes. When the jet stage was completed, I multiplied with the symmetry tool. This was done to avoid asymmetric engine flameouts, which depend (or at least used to depend) on part placement order.

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