Space X - Merlin engine

[derhp]

Hi team Kerbal.

So I've been playing since 0.8, and for a game that's still in alpha I have to say I'm impressed. I'm so impressed I'm going to try my hand at creating parts for the game.

My goal is to recreate, as accurately as possible, the merlin engine used by spacex on the 'Falcon' range of rockets. Once I have the engine done I shall move on to the fuel tanks, payload fairings, and crew module.

I thought I would start this thread to update on my progress, ask questions, and recieve feedback. As a bonus I already have two (2) questions!

1) Is there any reason why there are no 1.75 and 3 metre command modules BEYOND having to replace the command module in your install folder?

2) Spacex has a new launch vehicle planned, the Falcon Heavy. It is essentially a Falcon 9, with two extra falcon 9's strapped to each side as boosters. These boosters use a cross feed system so that all 27(!!!) engine are firing on liftoff, but keeps main tank full right up to booster seperation. How hard would it be to implement something like this in KSP?

Falcon heavy for the interested: http://www.spacex.com/falcon_heavy.php

cheers in advance 8)

EDIT: Formatting and adding link

[DoctorEvo]

1) Nope.

2) Very hard. Might be impossible. If you could fool the game into thinking the booster tanks were stacked 'above' the core tank through a little attach node black magic, then maybe it'd work. Maybe.

[Sordid]

1) Is there any reason why there are no 1.75 and 3 metre command modules BEYOND having to replace the command module in your install folder?

The reason is that KSP currently doesn't allow you to choose which CM to use even if you mave more than one.

2) Spacex has a new launch vehicle planned, the Falcon Heavy. It is essentially a Falcon 9, with two extra falcon 9's strapped to each side as boosters. These boosters use a cross feed system so that all 27(!!!) engine are firing on liftoff, but keeps main tank full right up to booster seperation. How hard would it be to implement something like this in KSP?

Not really possible in the current version. The devs have said that they plan to give parts various attributes tweakable from within the VAB. I'm assuming changing the order in which tanks are drained might be among those.

[Ninja]

1) Its doable, but mainly because it limits what sizes you can link it to on the stages below.

2) Exactly the sort of coupler I am currently working on, have the cross fuel flow working on a duel coupler but having issues with correctly decoupling. Ejects vertically rather than horizontally....

This thread probably needs moving though ;D

[Andras]

For 2) you can simulate it by giving the booster engines 50% more thrust and burn, and not firing the center engine until the boosters are empty.

That'll give you the effective thrust of 3 engines.

[Moach]

i'll say, this is a good point for a feature request

i kinda feel this would be important for advanced players to have... cross-feed lines could be implemented in the future (would be planned already, if it were up to me) as a subset feature of my whole 'systems view mode' suggestion for the VAB which would allow a nodes-and-wires interface to give rocket buillders a way to create intricate sensors-triggers-actuators sequences and effectively 'program' the vehicle to handle itself through whatever flight events....

but it's a long story.... fuel cross-feed would be only one of a whole world of possibilities if this were to become featured

BTW, i've moved your thread to the 'questions' board, seemed more fitting :

:cheers:

[derhp]

Cool beans Moach, putting this thread here rather than questions was an afterthought I now regret.

I should point out that for the sake of realism that the cross feed system spacex are working on is an entirely entirely new concept. When it's launched it will be the first rocket in history to employ such a system.

[Moach]

on an expendable launcher yes, it's quite new indeed (and very clever)... but other vehicles like the shuttle were doing pretty much that, with the external tank and all.... and cross-feed is something that's available in pretty much all commercial aircraft (spaceplanes would have this, no doubt)

i think it's a worthy feature to request... sure, there's oodles of ground to cover before getting to it, but one might as well bring it up now for future reference :

[Eat Uranium]

You could probably do it with a special kind of strut. You place the first end where you want the fuel to come from, and the second end where you want it to go.

[DoctorEvo]

Okay, so I found out that radial couplers have a fuelCrossFeed parameter... but it feeds the wrong way - outwards only.

[Howson]

Okay, so I found out that radial couplers have a fuelCrossFeed parameter... but it feeds the wrong way - outwards only.

Mount them backwards

[Ninja]

Mounting them backwards though results in ejecting the wrong way

It's something I am working on though so if I find a solution ill be happy to share how its done

[Howson]

Mounting them backwards though results in ejecting the wrong way

It's something I am working on though so if I find a solution ill be happy to share how its done

Give it a negative ejection force

[Andras]

Mount them backwards

Won't work, the system is hard-coded to feed from top down and center out.

It's impossible at the moment to feed a central engine from side mounted fuel tanks.

[Ninja]

It is possible to trick it though using the system I have in place for external fuel tank only the top 'Cone' section of the external tank has fuel, coupler is below that feeding into the shuttle and below the coupler is a dummy lower external fuel tank structure 'Strut' so it does cross feed correctly into the shuttle fuel tanks. However the problem is the decoupler set-up I am using to allow that does not allow for horizontal separation only vertical which means when you go to separate the cockpit of the shuttle is jettisoned....

Ive managed to get it to feed the fuel correctly but until I figure out the jettison issue its not much use.

[Tim_Barrett]

Mount them backwards

Can't, you would need your only command module (the one that works) to be connected to the booster, and then the main fuel tanks would be ghosted.

[Panichio]

Any progress on the parts lately?

Also, which rocket are you planning on doing? The Falcon 9 (DragonLab as well?) or the Falcon Heavy?

[derhp]

I\'m still teaching myself how to model, in between work and study. The plan, once I can get round to it (or once someone else does it, I really don\'t mind), Is to model the falcon 9 fuel tanks in 2m format, merlin engine, a 9 point engine adapter,a nozzle extender, and a decoupler clamp similar to novasiliskos. With those parts you should be able to produce the falcon 9 and falcon 9 heavy. I have no plans at this stage to model the dragon.

Regardless I don\'t see much point in releasing it until fuel feeding is tweaked, which harvester plans to do at some stage.

[azawada]

1) Nope.

2) Very hard. Might be impossible. If you could fool the game into thinking the booster tanks were stacked 'above' the core tank through a little attach node black magic, then maybe it\'d work. Maybe.

Its possible, just two decuplers would have to be used one that was cross fuel capable and one that wasnt

[Tiberion]

[mod]Closing this thread due to extreme Necro; Last post in October. If the original author wants to continue this thread, contact any moderator to have it re-opened.[/mod]