Porkjet

[1.0.5] Atomic Age - Nuclear Propulsion - Red Hot Radiators

Recommended Posts

The highest temperature is always where the reaction takes place. In case of chemical rockets it's the chamber where highest pressure is. In case of nuclear rockets it's the nuclear reactor core.

My point is - the end of the nozzle can not possibly be hotter than its neck.

You are right, and in both cases that point that heats up the most is the usually narrrowest point of the nozzle, and since this is a nuclear rocket that's probably where it should be.

However... It IS possible to have an appearance like this, since most LH2 burning engines are cooled by the cryogenic fuel, the hottest parts of the engine might actually be cooled below the point of incandescence, while cooler running parts of the engine like the end of the bell aren't cooled and so can heat up until they glow.

I am pretty sure this is what Porkjet is modeling, in the image you can see that the darkest part of the nozzle is right where the fuel line wraps around the nozzle, it is warmer both above and below this point because this is the spot where the coolant is running.

This image looks just like Porkjet's emissive:

ht-vulcain.jpg

Edited by Starbuckminsterfullerton

Share this post


Link to post
Share on other sites
And yet it is. As you have said the hottest (reactionmass) is the chamber and throat of a rocket whether it is nuclear or chemical. However I can not find a single picture of a rocket with a throat or chamber that is brighter than the bell.

lajoswinkler is correct about the temperatures on the inside, but for engine effects you need to model the temperature of the outside. There's going to be some active cooling of the throat and upper nozzle; a common way to do that is to circulate some of the cryogenic propellant through tubes running around the throat and nozzle. Where there is active cooling, the outside will be much cooler than the inside.

what I see in the (real engine) picture in #120 above is peak brightness just below the throat.

what I see in the KSP picture in #122 is peak brightness at the rim, which is wrong.

I'd expect the outside temperature to be cool near the throat due to active cooling, quickly rise to a peak just below any actively cooled area, and then fall off again as you go further down the nozzle. reverse the color gradient and you can make the engine in #122 look more like the one in #120...

Share this post


Link to post
Share on other sites

You have no idea how happy I am to find the nuclear lightbulb. It's been a favorite type of mine for a long time and I love it.

Share this post


Link to post
Share on other sites

Is there a way to 'toggle' the way this mod changes the stock nuke engine to fuel only? So that if I wished I could build a complete stock vessel and have the stock nuke go back to using LFO like before?

You know, if we can cycle through options on the tanks for fuel config, can we cycle through the engines themselves on which fuels they burn?

Share this post


Link to post
Share on other sites

I'd expect the outside temperature to be cool near the throat due to active cooling, quickly rise to a peak just below any actively cooled area, and then fall off again as you go further down the nozzle. reverse the color gradient and you can make the engine in #122 look more like the one in #120...

Starbuckminsterfullerton provided a great shot of a nozzle that doesn't match what you would expect and that is very close to the porkjet model. This is because there is the added factor of the thickness of the wall material which is an insulator. If it was uniform then your expectation would indeed be correct, but the wall actually thins as it moves away from the throat for 3 main reasons. Reaction mass temperatures decrease away from the throat so less insulation (and thus thickness) is needed to maintain a low enough temperature to stay sound. Pressures decrease away from the throat so less strength is needed so the wall can be thinner and/or can reach a higher temperature. The material near the bell has to also support the forces from further out on the bell so again has to be thicker and/or be at a lower temperature.

Share this post


Link to post
Share on other sites
I'd be interested. does it also produce waste?

and yes, I do know that they don't really work this way. but as explained above, they also can't be just made out of metal and nothing else, and it feels cheaty having a rocket which has a superb specific impulse without the downside of a special fuel. I do know that these rocket-motors are supposed to be fabricated on kerbin, and they can add whatever they want, but in a space station, there have limited supplies.

I attached the code.

Mind you, I´m no pro modder and it is just my personal ´test case´ to see what I could do in short time yesterday.

The stats are just placeholders to see what it would do.

Power generation is a bit wonky though and reactor ON/OFF fuctions not really well for the intended BIMODAL feature I had in mind.

I couldn´t figure out how to auto start/stop the reactor when the engine is deactivated.

Maybe a more senior modder can help me on this?

Just create a cfg file in the FTmN folder and it shoudl work for this engine.

PS it also adds NF convertion to liquid hydrogen fuel.

// Bl40n (Kommitz Nucleonics) ftmn40
@PART[bl40n]
{
@MODULE[ModuleEnginesFX] {
@PROPELLANT[LiquidFuel]
{
@name = LiquidHydrogen
@ratio = 1.0
}
!PROPELLANT[Oxidizer] {}
PROPELLANT
{
name = EnrichedUranium
ratio = 0.00025
}
}
RESOURCE
{
name = EnrichedUranium
isTweakable = false
amount = 12
maxAmount = 12
}
RESOURCE
{
name = DepletedUranium
isTweakable = false
amount = 0
maxAmount = 12
}
MODULE
{
name = ModuleGenerator
requiresAllInputs = true
isAlwaysActive = false
activateGUIName = Reactor ON
shutdownGUIName = Reactor OFF
OUTPUT_RESOURCE
{
name = ElectricCharge
rate = 10.00
}
OUTPUT_RESOURCE
{
name = DepletedUranium
rate = 0.0000025
}
INPUT_RESOURCE
{
name = EnrichedUranium
rate = 0.0000025
}
}
MODULE
{
name = ModuleAlternator
RESOURCE
{
name = ElectricCharge
rate = -15.0
}
}
}

Share this post


Link to post
Share on other sites

I found a funny thing when trying to mate Lightbulb with KM_Gimbal_3 just for giggles.

Here's the code snippet:


@PART[nuclearEngineLightbulb]:NEEDS[KM_Gimbal]
{
// I wasn't able to look it up via just module name :-\
!MODULE:HAS[#gimbalRange[7]]:NEEDS[KM_Gimbal] {
-name = ModuleGimbal
-gimbalTransformName = Reactor
-gimbalRange = 7
}
MODULE:NEEDS[KM_Gimbal] {
name = KM_Gimbal_3
gimbalTransformName = Reactor
trustTransformName = gimbal
yawGimbalRange = 24
pitchGimbalRange = 24
responseSpeed = 10
//gimbalConstrain = 26 // ignored unfortunately, seems to be hardcoded at 14
}
}

In-game the gimbal is unuseable: X trim works fine, but when I change Y trim, it rotates along longitudal axis, (not tilts). SAS and MJ SmartASS do the same, so the ship starts to spin. What can be wrong?

Share this post


Link to post
Share on other sites
I found a funny thing when trying to mate Lightbulb with KM_Gimbal_3 just for giggles.

Here's the code snippet:


@PART[nuclearEngineLightbulb]:NEEDS[KM_Gimbal]
{
// I wasn't able to look it up via just module name :-\
!MODULE:HAS[#gimbalRange[7]]:NEEDS[KM_Gimbal] {
-name = ModuleGimbal
-gimbalTransformName = Reactor
-gimbalRange = 7
}
MODULE:NEEDS[KM_Gimbal] {
name = KM_Gimbal_3
gimbalTransformName = Reactor
trustTransformName = gimbal
yawGimbalRange = 24
pitchGimbalRange = 24
responseSpeed = 10
//gimbalConstrain = 26 // ignored unfortunately, seems to be hardcoded at 14
}
}

In-game the gimbal is unuseable: X trim works fine, but when I change Y trim, it rotates along longitudal axis, (not tilts). SAS and MJ SmartASS do the same, so the ship starts to spin. What can be wrong?

Unless the KM gimbal module actually uses a mispelled field then you've got a spelling error in there I think.

trustTransformName. Shouldn't that be thrustTransformName?

Share this post


Link to post
Share on other sites

Indeed seems like it is misspelled there - for example km_ssme_rs25ss which is in Klockheed_Martian_SSE/Parts/Ssme-s-Straight/part-straight.cfg has it like so... I copied from their parts IIRC, in times of 0.23. That worked on "my" other engines (J-2S, J-2X, F-1B, M-1 etc). May well be that that parameter creeped there and is in fact ignored.

Edited by cipherpunks

Share this post


Link to post
Share on other sites

Ok, I tracked down the source and the only field for named transforms is gimbalTransformName. There is none for thrust at all under any spelling.

The section also where you're trying to remove KM_Gimbal is way more complicated than it needs to be and I'm skeptical that it's doing what you're intending. Have you taken a look at your Module Manager cache file? Do so, find the lightbulb part in there and verify that it's actually removed. (on the other hand, if you don't even have the original KM_Gimbal plugin actually present then removing the config is superfluous)

Share this post


Link to post
Share on other sites

Whoa, thank You man, You taught me about ModuleManager.ConfigCache - thank You! I've used to Alt+F12 -> Debug -> Parts -> scroll down then scroll right dance, but looking at this file is much, much handier, moreover Far Manager which I use for editing has a search :-) (if interested, also see PlugRing). Besides, Alt-F12 doesn't show cloned parts (which I copy with +PART), but now I know...

Anyway, here's what the only relevant gimbal code looks like in that cache:

        MODULE {
name = KM_Gimbal_3
gimbalTransformName = Reactor
yawGimbalRange = 24
pitchGimbalRange = 24
responseSpeed = 10
}

and what Lightbulb does is it still rolls.

When I press pitch, it tries to move accordingly, but has funny convulsions.

When I press roll, it does nothing as it should (or does roll if I activate roll from KM_Gimbal_3)

When I press yaw, it rolls.

Edited by cipherpunks
added Far link

Share this post


Link to post
Share on other sites

Okay, so this mod is great, and we now have LV-Ns that use Liquid Fuel only, great! And I do agree completely with the idea that the fuel tanks would need to be less dense, and basically what I'm trying to say is that some support to use the fuelswitch config from the Cryogenic Rockets Pack would be a cool thing to have. It would keep the whole low-density thing that stock does, and all that jazz.

Edited by GregroxMun

Share this post


Link to post
Share on other sites

Okay this isn't working in 1.0, can't find them in the tech tree in career, they appear in my parts list in sandbox however.

Share this post


Link to post
Share on other sites

Bumping this, if anyone knows how I can alter the files to get it working I'd appreciate it.

Share this post


Link to post
Share on other sites
Okay this isn't working in 1.0, can't find them in the tech tree in career, they appear in my parts list in sandbox however.

That's an easy fix, open the part.cfg files for both engines and alter the TechRequired field to nuclearPropulsion.

But that's not all that's required. The bottom attachment node is wrong, you can´t fit a decoupler and have it work. That I don't know how to fix.

Share this post


Link to post
Share on other sites
That's an easy fix, open the part.cfg files for both engines and alter the TechRequired field to nuclearPropulsion.

But that's not all that's required. The bottom attachment node is wrong, you can´t fit a decoupler and have it work. That I don't know how to fix.

Dammit, well thanks, im not rushing through career so maybe it will get updated before i get to ntr's.

Share this post


Link to post
Share on other sites

Bump also. Can someone make a MM patch for the parts fix nodes???

Share this post


Link to post
Share on other sites
But that's not all that's required. The bottom attachment node is wrong, you can´t fit a decoupler and have it work. That I don't know how to fix.

It has to do with a change in how the bottom node attaches. you need to change the cfg from:

node_stack_bottom = x, y, z, angx, angy, angz, size

To (notice the now negative 5th value):

node_stack_bottom = x, y, z, angx, -angy, angz, size

Share this post


Link to post
Share on other sites

Hey all! I'm updating this right now, adding a new engine aswell while I'm at it, expect it tomorrow-ish!

Share this post


Link to post
Share on other sites
hey all! I'm updating this right now, adding a new engine aswell while i'm at it, expect it tomorrow-ish!

AAAWESOOOME

Porkjet, you are the best.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now