[WIP]Nuclear Salt Water Rocket dev thread

[shynung]

Disclaimer: I am a total noob in regards to KSP modding. My coding skills are not the best in the world. I can't make part models worth a damn. So essentially, I'm doing the "stone soup" approach to making a mod.

So here's the deal. I plan on making an engine mod based on the concept of the Nuclear Salt Water Rocket. Basically, a uranium salt solution in water is injected into a cylindrical reaction chamber, allowing it to undergo nuclear fission. This reaction turns the water into superheated steam, which is then expelled through the rocket nozzle, creating thrust.

To summarize, the plan is as follows:

-3.75m fuel tank, carrying a special fuel resource (NuclearSaltWater). Effective tank capacity is 50% of standard tank volume, simulating boron carbide neutron damper to keep the tank contents from going critical.

-3.75m engine, 11t mass, 2150kn thrust, 6728s vacuum Isp. (Specs are subject to later changes.)

-ISRU capable, using CRP. MM config to make stock ISRU converter make NuclearSaltWater out of Uraninite and Water.

UPDATE: Prototype configs are uploaded to GitHub. Feel free to try doing things.

Any advice on balancing will be highly appreciated.

GITHUB REPOSITORY

RELEASES

Credits:

Modelling and Textures: ThatOneBritishGuy...

Configuration files: shynung

Advisor: FreeThinker

License:

This project is public domain. I take no responsibility for any damages that may occur by the use of this project. Use at your own risk.

Edited February 20, 2017 by shynung

[shynung]

Here's a prototype config that I just slapped together:

//Nuclear Salt Water Rocket - part config
//MIT License

PART//:NEEDS[CommunityResourcePack]
{
	name = NSWR-Engine
	module = Part
	author = NovaSilisko, shynung
	mesh = Squad/Parts/Engine/liquidEngineLV-N/model.mu
	scale = 1
	rescaleFactor = 1
	node_stack_top = 0.0, 1.40383, 0.0, 0.0, 1.0, 0.0
	node_stack_bottom = 0.0, -1.731957, 0.0, 0.0, -1.0, 0.0
	fx_exhaustFlame_blue = 0.0, -1.6, 0.0, 0.0, 1.0, 0.0, running
	fx_exhaustLight_blue = 0.0, -1.6, 0.0, 0.0, 0.0, 1.0, running
	fx_smokeTrail_light = 0.0, -1.6, 0.0, 0.0, 1.0, 0.0, running
	sound_vent_medium = engage
	sound_rocket_hard = running
	sound_vent_soft = disengage
	sound_explosion_low = flameout
	TechRequired = nuclearPropulsion
	entryCost = 45000
	cost = 10000
	category = Engine
	subcategory = 0
	title = "Zubrin" Nuclear Salt Water Thruster
	manufacturer = ShyTech Engineering
	description = Despite the big scary trefoil painted onto the side of this engine, its radioactive exhaust, and tendency to overheat, the LV-N Atomic Rocket Motor is harmless. Mostly. Note that the LV-N is the only LV series engine to run solely on Liquid Fuel - the future is glowing bright!
	attachRules = 1,0,1,0,0
	mass = 1.5
	// heatConductivity = 0.06 // half default
	skinInternalConductionMult = 4.0
	emissiveConstant = 0.85 // engine nozzles are good at radiating, NTRs even better
	dragModelType = default
	maximum_drag = 0.2
	minimum_drag = 0.2
	angularDrag = 2
	crashTolerance = 12
	maxTemp = 2500 // = 4000
	bulkheadProfiles = size1
	radiatorMax = 0.35 //Default = 0.25 but nuke engines are meant to run hot
	MODULE
	{
		name = ModuleEngines
		thrustVectorTransformName = thrustTransform
		exhaustDamage = True
		ignitionThreshold = 0.1
		minThrust = 0
		maxThrust = 60
		heatProduction = 1000
		fxOffset = 0, 0, 1.6
		EngineType = Nuclear
		PROPELLANT
		{
			name = Water
			ratio = 0.998
			DrawGauge = True
		}
		PROPELLANT
		{
			name = EnrichedUranium
			ratio = 0.002
			DrawGauge = True
		}
		atmosphereCurve
		{
			key = 0 8000
			key = 1 500
			key = 2 0.001
		}
	}
	MODULE
	{
		name = ModuleJettison
		jettisonName = fairingL
		bottomNodeName = bottom
		isFairing = False
		jettisonedObjectMass = 0.1
		jettisonForce = 1
		jettisonDirection = 1 0 0
	}
	MODULE
	{
		name = ModuleJettison
		jettisonName = fairingR
		bottomNodeName = bottom
		isFairing = False
		jettisonedObjectMass = 0.1
		jettisonForce = 1
		jettisonDirection = -1 0 0
	}
	MODULE
	{
		name = ModuleAnimateHeat
		ThermalAnim = overheat
	}
	MODULE
	{
		name = ModuleAlternator
		RESOURCE
		{
			name = ElectricCharge
			rate = 5.0
		}
	}
	RESOURCE
	{
		name = ElectricCharge
		amount = 0
		maxAmount = 0
		isTweakable = false
		hideFlow = true
	}
	MODULE
	{
		name = ModuleTestSubject
		environments = 8
		useStaging = False
		useEvent = True
	}
	MODULE
	{
		name = ModuleSurfaceFX
		thrustProviderModuleIndex = 0
		fxMax = 0.7
		maxDistance = 50
		falloff = 2.5
		thrustTransformName = thrustTransform
	}
}

Though, for some reason, the KSP executable cannot find the model, so the part didn't load.

Error log:

[LOG 15:50:18.869] PartLoader: Compiling Part '/NSWR/NSWR-Engine'
[ERR 15:50:18.877] PartCompiler: Cannot clone model from '' directory as model does not exist

[ERR 15:50:18.878] PartCompiler: Cannot compile model

[ERR 15:50:18.878] PartCompiler: Cannot compile part

Can anyone clarify where did I derped? Thanks in advance.

[FreeThinker]

I actualy considered adding a salt core rocket to KSPI as a precursor to the Vista engine, but I couldn't find a good model for it. The Nucleal Salt water is potential very powerfull low tech technology which offers high thrust, at a relatively high Isp . However it would need some serious limitations to get balanced correctly because just using it raw power would be too overpowered. It should suffer from som serious overeating issues and cannot be throttled like regular chemical engines. To keep the nozzle from melting after several seconds, it would require some extreme cooling, making the engine heavy.

Also extreme measures must be taken to prevent contamination. For example, It should only be allowed to operate after reacting orbit, otherwise the exaust would contaminate the entire atmosphere with radiactive dust, slowly killing all life. The Salt water reactor is many times worse than project orion in terms of radiation because 99% of all enriched uranium would not be unused for fission.

To realise this, you cannot simply put together some Stock parts, it would require a specialed controler, similar to the KSPI Vista controller.

Note EnrichedUranium would not be a good resource for several resons.

For one, it not trasferable, which Niclear Salt Water is.

Second, it requires some specialised tanks.

Third the density and other properties are all wrong. It should be slightly more dense than normal water. Al alternative would be UraniumNitrate, which could be mixed with regular water to create a nuckear salt water rocket.

Edited August 31, 2015 by FreeThinker

[shynung]

Actually, yes, I intended it to be slightly overpowered. With a little twist: a single engine generates so much heat, even a quadruplet of large deployable radiators can barely keep it from exploding. So heat management, not cost or performance, is going to be the limitation.

You are correct, though, on the exhaust gases being radioactive, and the nuclear radiation generated by this thing thrusting. However, I plan to put this one on hold right now, until I learned some coding to prevent this thing firing at certain conditions - having another ship nearby not already docked in, for instance.

Despite that, I think we can just have this thing firing it atmosphere; the Kerbal people seem to have no problem firing off Porkjet's nuclear lightbulb engine right on the pad, so why not this one?

[FreeThinker]

Despite that, I think we can just have this thing firing it atmosphere; the Kerbal people seem to have no problem firing off Porkjet's nuclear lightbulb engine right on the pad, so why not this one?

Well Porcjet Nuclear LightBulb engine is a closed cycle gas core reactor. This explains their low performance and it's ability to allowed and function in the atmosphere. A big step up are open cycle design which can react much higher core temperatures at the expanse of lose a bit of uranium whenever the engine is under acceleration. This is the reason they cannot be developed on earth. Salt Water reactor are many times worse as 99% is dumped though the exasut, making effectivly a global dooms day weapon, many times worse than anything developed on conceived. A single atmospheric launch should be enough to radiate the entire atmosphere for many generations.

There are many good reasons why this engine wasn't developed, you absolutely have to be mad to even consider developing it.

Being powerfull it not a problem, but there needs to be a high cost and limitations to make it realistic and balanced

Edited September 13, 2015 by FreeThinker

[shynung]

Not 99%. 100% of fission material goes out of the exhaust. So yeah, apparently I will have to implement some sort of control measure to make sure it won't fire when in the wrong circumstances. However, I will hold this issue back until I can get the engine working, which for now I have failed to manage. I'll get back on that later.

On another point, I'm not aiming for all-out realism. I'm aiming for simplicity and interoperability with other mods, which is why I plan to use CRP's EnrichedUranium. If the density doesn't seem right, I'd ask RoverDude.

Also, I don't plan to have specialized tanks for uranium salt water propellant. Instead, the EnrichedUranium and the Water propellant are planned to be stored in separate tanks, to be combined in the engine when firing. Also, I may be able to avoid the issue of EnrichedUranium being untransferable by making the engine able to hold small amounts of it, enough for several tens of hours of firing at least.

I'd write more, but I'm on mobile right now.

Edited August 31, 2015 by shynung

[FreeThinker]

Well in that case I would simply replace "model.mu" by "model" and "EnrichedUranium" into "UraniumNitride" (A CRP resource that can be accesed everywhere) and it should work with a tank of water and UraniumNitride on your vessel.

To prevent atmospheric usage you can simply set the atmpspheric curve very steep

        atmosphereCurve
        {
            key = 0 8000
            key = 0.001 0.001
            key = 1 0.000001
        }

THis will ensure you can only use it above the atmpshpere

Edited August 31, 2015 by FreeThinker

[NuclearNut]

But it will mean that you will not be able to use it in places with an atmosphere where minor contamination does not matter, places like duna and eve.

[shynung]

Yeah, it would make it pretty much impossible to use anywhere there's an atmosphere. NSWR is meant to have the TWR of a 1st stage booster while having the Isp of a nuclear engine. Making it unable to be used in any atmosphere would baffle people who would put this engine as a landing engine.

Except maybe on Tylo. That is one heck of a piece of rock. This will probably be its future role.

Also, I'm planning the resource system to be balanced around Karbonite/Karborundrum and Near Future stuff, so being able to share resources with them is an added advantage. While EnrichedUranium indeed cannot be moved around, UraniumNitride isn't used much by the mods I plan to balance against. I'd have to, for example, create a new converter (or maybe an MM config) to convert EnrichedUranium into UraniumNitride.

BTW, changed 'model.mu' to 'model'. Still failed to load, error logs state 'cannot clone model'. It's in my repo if you want to fiddle with it.

Edited August 31, 2015 by shynung

[FreeThinker]

But it will mean that you will not be able to use it in places with an atmosphere where minor contamination does not matter, places like duna and eve.

An engine which can operate in an atmosphere needs an narrow neck, which is going to be a major problem with this engine due to extrme heat, for this reason alone, it should only be allowed to operate in vacuum

- - - Updated - - -

Except maybe on Tylo. That is one heck of a piece of rock. This will probably be its future role.

Yes, atmpsphere less moon and planets would be ideal, both for landing and take off.

- - - Updated - - -

While EnrichedUranium indeed cannot be moved around,

Well EnrichedUranium could be used as a fuel outside the engine if you appply the replace by intermediate resource trick. Simply put, your NSWController would collect Water and EnrichedUranium anywhere on the vessel and convert it to special temperary NuclearSaltWwater resource located on the engine which can then be used as a propellant by the engine. I use a similar trick to convert TAC Water into KSPI LqdWater for KSPI Thermal noozles which can use any propellant. This trick also prevents accidental life support water from beeing used for propulsion. A concern you should think about as well. You don't want to kill your players Kerbals by spending all water on a vessel, now do you? This also one of the main reason to create a specialed NuclearSaltWater resource, it prevent mixing with drinkable water to keep the Crew alive.

Edited August 31, 2015 by FreeThinker

[shynung]

Well EnrichedUranium could be used as a fuel outside the engine if you appply the replace by intermediate resource trick. Simply put, your controller would collect Water and EnrichedUranium anywhere on the vessel and convert it to special temperary NuclearSaltWwater resource located on the engine which can then be used as a propellant by the engine. I use a similar trick to convert TAC Water into KSPI LqdWater inside KSPI Thermal noozles. This trick also prevents accidental life support water from beeing used for propulsion. A concern you should think about as well. You don't want to kill your players Kerbals by spending all water on a vessel, now do you?

Interesting. That would be a useful trick.

If only I understand how to actually do that. I might have to study KSPI for a while.

Also, I'm holding off on making the thing unusable in atmosphere. I put a comment near the atmo keys, just in case I change my mind later.

Which I probably will.

Edited August 31, 2015 by shynung

[Whirligig Girl]

Actually, yes, I intended it to be slightly overpowered. With a little twist: a single engine generates so much heat, even a quadruplet of large deployable radiators can barely keep it from exploding. So heat management, not cost or performance, is going to be the limitation.

You are correct, though, on the exhaust gases being radioactive, and the nuclear radiation generated by this thing thrusting. However, I plan to put this one on hold right now, until I learned some coding to prevent this thing firing at certain conditions - having another ship nearby not already docked in, for instance.

Despite that, I think we can just have this thing firing it atmosphere; the Kerbal people seem to have no problem firing off Porkjet's nuclear lightbulb engine right on the pad, so why not this one?

Actually, one of the blessings of the real NSWR is that its exhaust carries away much of its heat, acting as regenerative cooling. A few medium-sized radiators ought to do the trick for a real NSWR.

[Randazzo]

Hmm, I've not seen a solution on here yet and I can't get at Github from here, but, if you want to reference the LV-N model from another directory, you'll need to use a MODEL node

So replace this:

mesh = Squad/Parts/Engine/liquidEngineLV-N/model.mu

with this:

 
MODEL
{
model = Squad/Parts/Engine/liquidEngineLV-N/model
scale = 1, 1, 1
} 

[shynung]

Hmm, I've not seen a solution on here yet and I can't get at Github from here, but, if you want to reference the LV-N model from another directory, you'll need to use a MODEL node

So replace this:

mesh = Squad/Parts/Engine/liquidEngineLV-N/model.mu

with this:

 
MODEL
{
model = Squad/Parts/Engine/liquidEngineLV-N/model
scale = 1, 1, 1
} 

Thanks! That worked like a charm.

On another note, I think making a new fuel resource (NuclearSaltWater) might be somewhat more realistic. Atomic Rocket quote:

The fuel tanks are a bundle of pipes coated with a layer of boron carbide neutron damper. The damper prevents a chain reaction.

So what I'd be looking for now is an MM config to make the ISRU converter mix EnrichedUranium (or maybe Uraninite) with Water to make NuclearSaltWater, and an IFS config to make tanks carry this resource.

Also, my water-nuclearFuel ratio might be off-base. Advice in balancing is much appreciated.

Actually, one of the blessings of the real NSWR is that its exhaust carries away much of its heat, acting as regenerative cooling. A few medium-sized radiators ought to do the trick for a real NSWR.

Hmm. That may be right.

Looks like I'll be studying Zubrin's paper tonight.

Edited August 31, 2015 by shynung

[FreeThinker]

I would go with the Atomic Rocket advice on Uranium to Water Ratio. A bigger problem will be to determin what the correct DryMass to Fuel Mass ratio should be and how much space it requires. Notice I face a similar problem for the storage of UraniumNitride. If you would simply put them in a big container, they would go critical in a matter of seconds. Therefore it has to be stored in special containers which cause them to contain much less Fuel than their volume would suggest. A an indication, UraniumNitride require 10 times as much volume as could be stored in water. For NuclearSaltWater I would go for 50%/50% (so a 1000L tank would only contain 500 L of NuclearSaltWater and 500 for boron carbide plumbing )

Another advice I would give is to use square tanks, as this would be a logical form if you would create a " bundle of pipes coated with a layer of boron carbide"

Edited August 31, 2015 by FreeThinker

[rasta013]

Here's an ISRU file to start with although the input ratios may need to be tweaked a bit. Right now it's based off the MKS Uranite/Enriched Uranium conversion rate and adding water into the mix.

//ISRU NSWR Converter

@PART[iSRU]

{

MODULE

{

name = ModuleResourceConverter

ConverterName = NuclearSaltWater

StartActionName = Start Nuclear Saltwater

StopActionName = Stop Nuclear Saltwater

AutoShutdown = false

GeneratesHeat = false

UseSpecialistBonus = true

SpecialistEfficiencyFactor = 0.2

SpecialistBonusBase = 0.05

Specialty = Engineer //or scientist to make it a bit tougher

EfficiencyBonus = 1

INPUT_RESOURCE

{

ResourceName = Water

Ratio = 0.99915 //Change according to balance

FlowMode = STAGE_PRIORITY_FLOW

}

INPUT_RESOURCE

{

ResourceName = Uranite

Ratio = 0.00085 //Numbers based off MKS Enriched Uranium conversion rate

}

OUTPUT_RESOURCE

{

ResourceName = NuclearSaltWater

Ratio = 1

DumpExcess = false

}

}

}

[shynung]

I would go with the Atomic Rocket advice on Uranium to Water Ratio. A bigger problem will be to determin what the correct DryMass to Fuel Mass ratio should be and how much space it requires. Notice I face a similar problem for the storage of UraniumNitride. If you would simply put them in a big container, they would go critical in a matter of seconds. Therefore it has to be stored in special containers which cause them to contain much less Fuel than their volume would suggest. A an indication, UraniumNitride require 10 times as much volume as could be stored in water. For NuclearSaltWater I would go for 50%/50% (so a 1000L tank would only contain 500 L of NuclearSaltWater and 500 for boron carbide plumbing )

Another advice I would give is to use square tanks, as this would be a logical form if you would create a " bundle of pipes coated with a layer of boron carbide"

Agreed. I think a 50% reduction in effective tank volume would be a good approximation to the boron carbide plumbing.

Square tanks? Maybe if I somehow get to make my own parts.

Here's an ISRU file to start with although the input ratios may need to be tweaked a bit. Right now it's based off the MKS Uranite/Enriched Uranium conversion rate and adding water into the mix.

//ISRU NSWR Converter

@PART[iSRU]

{

MODULE

{

name = ModuleResourceConverter

ConverterName = NuclearSaltWater

StartActionName = Start Nuclear Saltwater

StopActionName = Stop Nuclear Saltwater

AutoShutdown = false

GeneratesHeat = false

UseSpecialistBonus = true

SpecialistEfficiencyFactor = 0.2

SpecialistBonusBase = 0.05

Specialty = Engineer //or scientist to make it a bit tougher

EfficiencyBonus = 1

INPUT_RESOURCE

{

ResourceName = Water

Ratio = 0.99915 //Change according to balance

FlowMode = STAGE_PRIORITY_FLOW

}

INPUT_RESOURCE

{

ResourceName = Uranite

Ratio = 0.00085 //Numbers based off MKS Enriched Uranium conversion rate

}

OUTPUT_RESOURCE

{

ResourceName = NuclearSaltWater

Ratio = 1

DumpExcess = false

}

}

}

Thanks! I'll be sure to add that up.

Edited August 31, 2015 by shynung

[FreeThinker]

Square tanks? Maybe if I somehow get to make my own parts.

Notice, the standard RCS tank, could serve as a not so bad Plumbed tank as well:

I always wondered what the designer of this tank had in mind when created the pipes look, perhaps boron carbide pipes

- - - Updated - - -

Agreed. I think a 50% reduction in effective tank volume would be a good approximation to the boron carbide plumbing.

A nice bonus of these specialised tanks is that they will help create balanced gameplay for the saltwaterreactor engine, as the vessel will not be light an nimble, and require additional rcs and reaction wheels to control. This also justifies giving them the true power they posses.

Another thing I think you should consider is to increase the minumum size. One fact of nuclear fysics is that you need a minimum amount of fissile material to make uranium go critical. This effectively means, you cannot create small atomic weapons or small nuclear engines. You need a minimum amount of uranium to be effective. For Salt Water Reactor, due to the low density of uranium this should be several magnitudes larger than 1.25m reactor. In realsity this would translate to engines with a diameter of at least 10m . For gameplay reasons, I would shrink this to a 3.75m engine. Your not going to build NSWE to send probes, it's for serious manned missions.

A realistic 3.75m model would have a mass of 11t, generate 4300 kN thrust with an ISP of 6728s. Eventhough this seems overpowered, if you couple this with its atmospheric limitations, the heavy specialised tanks and the high cost of the uranium, it becomes well rounded part.

Edited August 31, 2015 by FreeThinker

[shynung]

Hmm, but that 2.5m RCS tank is too short. I don't know how to lengthen it. Right now I'm using Jumbo-64 tank models, but I have a problem:

The scaling was suboptimal; it was supposed to be the same size as the regular Jumbo-64 right above it. The NSWR is stuck on the bottom.

Tank config:

PART
{
	name = NuclearSaltWaterTank
	module = Part
	author = shynung
	MODEL
		{
		model = Squad/Parts/FuelTank/fuelTankJumbo-64/model
		scale = 1, 1, 1
	}
	node_stack_top = 0.0, 3.75, 0.0, 0.0, 1.0, 0.0, 2
	node_stack_bottom = 0.0, -3.75, 0.0, 0.0, -1.0, 0.0, 2
	node_attach = 1.25, 0.0, 0.0, 1.0, 0.0, 0.0, 1
	TechRequired = advFuelSystems
	entryCost = 24200
	cost = 5750
	category = FuelTank
	subcategory = 0
	title = Nuclear Salt Water Tank
	manufacturer = ShyTech Engineering
	description = This fuel tank is actually a bundle of boron-carbide pipes, designed to store uranium-laced water while keeping it from going critical inside the tank.
	attachRules = 1,1,1,1,0
	mass = 4
	dragModelType = default
	maximum_drag = 0.2
	minimum_drag = 0.3
	angularDrag = 2
	crashTolerance = 6
	breakingForce = 200
	breakingTorque = 200
	maxTemp = 2000 // = 2900
	bulkheadProfiles = size2, srf
	RESOURCE
	{
		name = NuclearSaltWater
		amount = 16000
		maxAmount = 16000
	}
}

I have the feeling the tank capacity is way off. I mean, 25 km/sec from a single tank?(the regular Jumbo-64 above is full.) I must have made a mistake somewhere.

Hmm. I like your idea of the engine specs. That might actually work.

Edited August 31, 2015 by shynung

[Randazzo]

You'll need to add

rescaleFactor = 1

If you don't specify this line, it defaults to 1.25, meaning your whole model gets sized up 25%.

With regard to the massive dV value, keep in mind that right now the vast, vast majority of your vessels mass is fuel. As you add more payload mass, that value will drop. By how much, I couldn't say.

[shynung]

You'll need to add

rescaleFactor = 1

If you don't specify this line, it defaults to 1.25, meaning your whole model gets sized up 25%.

With regard to the massive dV value, keep in mind that right now the vast, vast majority of your vessels mass is fuel. As you add more payload mass, that value will drop. By how much, I couldn't say.

Thanks.

Actually, the fuel tanks are supposed to have much less fuel than their standard brethren. 50% of internal volume is abstracted to be taken up by boron carbide neutron dampers.

[Randazzo]

Thanks.

Actually, the fuel tanks are supposed to have much less fuel than their standard brethren. 50% of internal volume is abstracted to be taken up by boron carbide neutron dampers.

So, assuming the same density, that tank should have 3200 fuel. It has 16,000.

[shynung]

Yep. I certainly derped on that one. Though, 3200 fuel was assuming the fuel has the same density as regular LiquidFuel; the NuclearSaltWater fuel have only 1/5 of the density.

Also, I'm planning to rescale everything to 3.75m. Specs on the OP. Need rebalancing on fuel tank capacity; right now, the tank is a Jumbo-64 upscaled by 150%.

Edited August 31, 2015 by shynung

[Randazzo]

Not sure if you're trying to be a wiseguy, but I'll just head on out now and leave you to it. Glad I could help get things working for you.

[shynung]

Nah, just messing with you. Thanks for the help, though, really appreciate it.

Nuclear reactions have a minimal limit in the form of critical mass. Get lower than this, and no nuclear reaction. So, I assumed that everything has to be big, and upscale stuff accordingly.

Not sure if it was too big, though. If you have any more suggestions, I'm all ears.

Edited August 31, 2015 by shynung