[0.90] KSP Interstellar port maintance thread

[Atrius129]

So I am trying make some quantum vacuum RCS thrusters (As per Angel-125's apparently abandoned project):

MODULE

{

name = ModuleRCS

thrusterTransformName = RCSthruster

thrusterPower = 1

resourceName = ElectricCharge

resourceMass = 0.0001

atmosphereCurve

{

key = 0 260

key = 1 100

}

}

This actually semi works, the problem being all EC is totally drained and refilled extremely rapidly. I built a tiny probe with several thousand EC + 1.25 fusion reactor and gene + 8 QV RCS thrusters. It seems that no matter how much battery life there is it is instantly drained by the thrusters and refilled by the fusion reactor. This switches off SAS but RCS remains on. I know the issue is probably that EC has none of the weight that is being called for and instead should be some type of resource per second rate. I guess the Quantum Vacuum (or MJ) resource would be better to use than EC. Any help to get this resolved would be greatly appreciated.

Ultimately I would like to continue with his repulsor idea that would allow large craft to translate easily using the RCS commands.

Edited February 7, 2015 by Atrius129

[Northstar1989]

Well, for now I can implement it like this

Trust = Max ((Trust in kN in Space) - ((Exit Area Trust Modifier) * (Background Pressure )), 0)

(where Pressure is atmospheric pressure @ Kerbin sea level)

Looks good to me, although I'll admit I'm looking at this rather late at night... In fact, it took me quite a while to realize that what you had there was a

Thrust = Max (Function, 0)

type of programming-logic. Which makes sense (as you don't want negative thrust), but at first had me *very* confused, because I thought you meant the maximum Thrust the part is theoretically capable of in space (rather than what it is actually capable of achieving based on levels of beamed-power and/or its Throttle Setting), rather than a computing/mathematical-logic max ( f(x), 0) statement...

Just make sure you actually do use the Thrust the vessel would normally achieve with that throttle/ level of microwave beamed-power in space (and that throttle and power-level ONLY), otherwise you'll get some *VERY* wonky results- like a Plasma Thruster operating at 0.7% of maximum theoretical thrust (with a TWR limiter of 7%, and throttle at 10%) with just a few kW of power getting the same sea-level ISP as a Plasma Thruster at 100% throttle with literally a Gigawatt of power available (more than enough to reach the part's power-limit) which just simply shouldn't happen!

As I pointed out before, the reason electric thrusters have such poor ISP at sea-level is because they have very poor Thrust (and thus Mass-Flow) to begin with, *NOT* because they have high Exhaust Velocity (which actually HELPS REDUCE atmospheric compression at the same mass-flow rate...)

At least this should give similar atmospheric trust behavior, but determining the exact value for ExitAreaTrustModifier will be something you have to figure out for every engine type. I will provide a initial value which should give about 50% trust @ kerbin sea level for Hydrogen at full power.

Whoa, whoa. Back off there for a minute. You're assuming that 50% thrust-loss for a Hydrogen plasma-thruster at *FULL* power is even VAGUELY realistic...

Hydrogen at full-power represents literally more than 40 kN of thrust for a 0.625 meter engine with a tiny engine nozzle! The thrust-loss at Exhaust Pressures that high should be negligible! For comparison, just look at the small Rockomax engine- which in Realfuels+Stockalike produces just over 32 kN of Thrust in vacuum at Tech Level 5!

They have *very* similarly-sized engine-nozzles (the chemical rocket's is a bit taller, and thus larger overall). The chemical rocket doesn't lose 50% of its thrust at sea-level! And neither should the plasma thruster! (here comes a very important point, at MAXIMUM THRUST of 40+ kN this holds true- at only a few hundred Newtons of thrust the Plasma Thruster's sea-level ISP should approach zero...)

At those thrust-levels, and with a nozzle that size, the Exhaust Pressure is such that a rocket (chemical OR electric- remember higher Exhaust Velocity makes up for reduced Mass Flow when it comes to Exhaust Pressure...) only loses about 5.7 kN of thrust (out of 32 kN) at sea-level. So, if the plasma thruster is operating at 3.125 Gigawatts of power (the maximum power and thrust-level for that thruster design) it should lose LESS than 5.7 kN of Thrust (it has a smaller Exit Area) itself... A list might help:

OBSERVED Rockomax 48-7S Chemical Rocket Performance:

Vacuum ISP: 337 seconds

Sea-Level Thrust: 32 kN

Sea-Level ISP: 277 seconds

Sea-Level Thrust: 26.3 kN (note that fuel-flow comes out to be the same in both conditions!)

CORRECT KSP-I 0.625 meter Plasma Thruster Performance at 3.125 GW of power using Hydrogen:

Vacuum ISP: 11213 seconds

Vacuum Thrust: 42 kN

Sea-Level ISP: > 9692 seconds

Sea-Level Thrust: > 36.3 kN

Hardly 50% thrust-loss now, is that? (in fact, it's only about 14% thrust-loss)

And just for fun:

PREDICTED KSP-I 0.625 meter Plasma Thruster at 312.5 MW of power using Hydrogen:

Vacuum ISP: 11213 seconds

Vacuum Thrust: 4.2 kN

Sea-Level ISP: approximately -4004 seconds (obviously impossible- the idealized rocketry equation used breaks down at very low Exhaust Pressure)

Sea-Level Thrust: -1.5 kN (at extremes like this, the idealized rocketry equation used breaks down- obviously there's no negative thrust)

One more, shall we?!

CORRECT KSP-I 0.625 meter Plasma Thruster Performance at 3.125 GW of power using Hydrazine/Monopropellant:

Vacuum ISP: 2803.25 seconds

Vacuum Thrust: 118.125 kN

Sea-Level ISP: > 2668 seconds

Sea-Level Thrust: > 112.425 kN (remember, the nozzle is SMALLER than a 48-7S, so these estimates are conservative!)

That's only approximately 4.825% thrust (and ISP) loss at sea-level! It HELPS you accept it when you remember that the thruster is spitting a considerable (over 12% as much as the chemical thruster, in fact!) mass of Hydrazine out the nozzle at over 27,470 m/s though!

I'm going to simplify this down at much as possible, because my previous explanations have been over-complicated:

What determines the degree of thrust-loss of an engine in-atmosphere is the relationship between the amount of thrust produced (in vacuum) and the size of the exhaust nozzle.

ISP, fuel-density, none of that matters! (and is all included within the beauty of the terms "(Specific Impulse) * (Mass Flow Rate)", as an engine with TWICE the ISP only requires HALF the Mass Flow Rate to achieve the same Thrust, and so on an so forth...) What matters is how large the nozzle (Exit Area) is compared to the Thrust produced (in vacuum), and what the ambient pressure (Background Pressure) is on that planet/moon! This provides you a perfect understanding of how high the Exhaust Pressure is (at least for an ideal rocket!)

Sure, there is the matter of Nozzle Efficiency in real life (i.e. that a rocket might produce less thrust than you would expect for its Exhaust Pressure- in which case basing Thrust-loss on Vacuum Thrust will over-estimate the effect of atmospheric-compression), but this is KSP! We simplify things so that we can understand (and play with) them!

Even a simple relationship like this function that alters Thrust based on atmospheric pressure (if implemented correctly, this function should entirely overwrite the stock logic for Atmosphere-curve, and cause Mass Flow to remain fixed for 100% throttle while increasing/decreasing thrust based on atmospheric pressure- the same as in RealFuels but a bit more complicated to reflect differences in throttling and available Microwave Beamed Power that are rarely so drastic with chemical rockets as with thermals/electrics...) is far beyond what the stock game normally provides! You should be proud of yourself for just wanting to implement a more realistic relationship between sea-level ISP and Thrust based on real (but idealized) rocketry equations!

Regards,

Northstar

P.S. I wouldn't want to be standing down-stream of that Hydrazine Thruster! In fact, it reminds me of an old principle of Science Fiction- the higher the ISP of your propulsion system, the more powerful its exhaust-stream can function as a potential weapon!

Edited February 7, 2015 by Northstar1989

[FreeThinker]

CORRECT KSP-I 0.625 meter Plasma Thruster Performance at 3.125 GW of power using Hydrogen:

Vacuum ISP: 11213 seconds

Vacuum Thrust: 42 kN

Sea-Level ISP: > 9692 seconds

Sea-Level Thrust: > 36.3 kN

Great, this is exactly what I can use.

From this deduced the following exitArea values (

MPD 62.5 cm: 5.7

MPD 125 cm: 22.5 (4x surfice area exitArea 62.5)

MPD 250 cm : 91.4 (4x surfice area exitArea 250)

And Athmosphere ISP = Vacuum ISP * ((Vacuum Trust - exitArea * Athosphere) / Vacuum Trust)

Edited February 7, 2015 by FreeThinker

[FreeThinker]

I uploaded a new version of KSP Interstellar Extended 0.5.3 at KerbalStuff.

Features

• Made ISP/Trust performance of Plasma Engine in atmosphere depend on engine nozzle surface and atmospheric pressure
  
• Added support for other Techtrees
  
• Added ability of Atmospheric Scoop to function as Propulsive fluid accumulator which can be achieved by placing a vessel in a circular orbit at the edge of space with access to KSPI plasma engines and enough power.
  
• Electric engines power usage is limited by available power (optional)
  
• Added many new configuration settings including MaxThermalNozzleIsp, RadiationMechanicsDisabled
  
• Added Liquid Nitrogen en (RealFuels) Nitrogen as a resource which can be used for Thermal/Magnetic/Electric Rockets
  
• Added Cryotank which stores Liquid Nitrogen at low temperature, requiring electric power to maintain
  
• Added Integrated Nitrogen Radiator which stores Nitrogen gas and can perform Active cooling with Liquid Nitrogen
  
• Nitrogen can be scooped from the atmosphere with Atmospheric Scoop
  
• Improved Science Lab research : Profession & Skill now matter (+/- 50%) , effect of stupidity reduced (+/- 10%)
  
• Improved Science Lab feedback, it will at real time show how much science is already collected
  

Fixes

• Fixes KSPI Legacy issue where Reactors Retrofit(upgrade) button would not function
  
• Fixed KSPI Legacy issue where stupid Kerbals would actually improve research output in the Lab
  
• Fixes KSPI Legacy issue where Athmospheric scoop would not reset flow to 0 when flying out of atmosphere
  
• Fixes KSPI Legacy issue where Double Pivoted Solar Power generators could not be converted to Microwave power
  

Installation

• First remove any existing KSPI installation (GameData\WarpPlugin folder)
  
• Second install KSPI 0.90
  
• Third extract the KSPI Extended Patch into Your GameData folder.
  

Edited February 7, 2015 by FreeThinker

[etmoonshade]

FreeThinker: there's definitely something wrong with reactors and thermal power even in the newest version. I have the following two screenshots, with the first taken at 10000x warp and the second at 1x warp.

https://dl.dropboxusercontent.com/u/22571912/Pics/Spaceflight/KSP%20Screens/screenshot0%20%282%29.png

https://dl.dropboxusercontent.com/u/22571912/Pics/Spaceflight/KSP%20Screens/screenshot1%20%283%29.png

As you can see, going to 10000x warp will give the expected reactor output drop to 25% once thermal power is maxed. When I go to 1x warp though, it drains thermal power to roughly the displayed level and naturally, goes to 100% output and stays there (because it's trying to catch up.)

I also reproduced this problem on a new install of KSP with only KSP-I and KSP-I Extended installed - it's definitely something in the plugin.

Anyway, thanks for the work you and Boris have done, and I'll leave y'all alone and stop complaining now. ;p

[FreeThinker]

FreeThinker: there's definitely something wrong with reactors and thermal power even in the newest version. I have the following two screenshots, with the first taken at 10000x warp and the second at 1x warp.

https://dl.dropboxusercontent.com/u/22571912/Pics/Spaceflight/KSP%20Screens/screenshot0%20%282%29.png

https://dl.dropboxusercontent.com/u/22571912/Pics/Spaceflight/KSP%20Screens/screenshot1%20%283%29.png

As you can see, going to 10000x warp will give the expected reactor output drop to 25% once thermal power is maxed. When I go to 1x warp though, it drains thermal power to roughly the displayed level and naturally, goes to 100% output and stays there (because it's trying to catch up.)

I also reproduced this problem on a new install of KSP with only KSP-I and KSP-I Extended installed - it's definitely something in the plugin.

Anyway, thanks for the work you and Boris have done, and I'll leave y'all alone and stop complaining now. ;p

Your correct, the 100% output is intended to keep the reactor prepared for energy consumption (instead of reactionary). It allows a more realistic energy matching between supply and demand. KSP Interstellar allows it's MegaWatt buffer to act like a super power megawatt battery. However this feature is not intended to be active by default (and not visible). As you correctly noticed, it disabled itself at higher time warp (at more than 20x), so it would not effect consumption in a serious way. For now I made it function as it did. In the future I intend to improve it in a better way.

You can download the fixed version 0.5.3 from KerballStuff.

Edited February 7, 2015 by FreeThinker

[Northstar1989]

Great, this is exactly what I can use.

From this deduced the following exitArea values (

MPD 62.5 cm: 5.7

MPD 125 cm: 22.5 (4x surfice area exitArea 62.5)

MPD 250 cm : 91.4 (4x surfice area exitArea 250)

And Athmosphere ISP = Vacuum ISP * ((Vacuum Trust - exitArea * Athosphere) / Vacuum Trust)

Ack, NO, NO!

You're right that you can derive an *approximation* of Exit Area from the numbers I gave, but you did the math VERY wrong!

Those calculations were given using an approximation that Exit Area for the 0.625 m Plasma Thruster was *IDENTICAL* to the Rockomax 48-7S. As I made a point of saying, the Exit Area is smaller- the nozzle is slightly wider but not as tall...

Also, 5.7 kN is the value of Exit Area * Background Pressure at Sea-Level, NOT Exit Area alone.

The Rockomax 48-7S has an Exit Area of 5.7 kN / 101.325 kPa = 0.0562283 m^2

*NOT* 5.7 m^2. IF you use that value, Plasma Thrusters will be over 101 times more vulnerable to atmospheric compression than they should be, and will stop producing thrust at a much higher altitude (coming down from orbit) than they should!

A good approximation of the Exit Area of the 0.625 meter Plasma Thruster is a little over 85% of the Exit Area of the Rockomax 48-7S, or .048 m^2

The values for the 1.25 meter and 2.5 meter plasma thrusters then become:

1.25 meter: 0.192 m^2

2.5 meter: 0.768 m^2

Note that these are just approximations for the larger Plasma Thrusters, assuming they are direct re-scales.

All these approximations also assume that the Exit Area for the Plasma Thruster must be slightly smaller than the Rockomax 48-7S, as it is a slightly smaller nozzle with a generally similar shape...

I can get you approximations for the Exit Area of the ATTILA Thruster (has a significantly LARGER Exit Area than the Plasma Thruster, but many times more Thrust to compensate...) and the Thermal Rocket Nozzles relatively soon...

EDIT: I hope you're ready for this- the numbers for the ATTILA Thrusters and Thermal Rocket Nozzles are going to look QUITE different (MUCH larger Exit Areas).

Regards,

Northstar

P.S. A minor note- it's "Thrust" not "Trust". Your changelog perpetuates this spelling-error...

Edited February 7, 2015 by Northstar1989

[etmoonshade]

Your correct, the 100% output is intended to keep the reactor prepared for energy consumption (instead of reactionary). It allows a more realistic energy matching between supply and demand. KSP Interstellar allows it's MegaWatt buffer to act like a super power megawatt battery. However this feature is not intended to be active by default (and not visible). As you correctly noticed, it disabled itself at higher time warp (at more than 20x), so it would not effect consumption in a serious way. For now I made it function as it did. In the future I intend to improve it in a better way.

You can download the fixed version 0.5.3 from KerballStuff.

Unless it causes problems with engines, why not see about bumping down the storage for thermal power and megajoules? I see (and have actually experienced) your point - the only issue with leaving reactors at 100% is that it makes heat production really terrible, especially on things that are designed around never hitting max reactor output in the first place.

Thanks for the fix though - that's been driving me nuts in my designs.

Edited February 7, 2015 by etmoonshade
Production. Not consumption, production. Even if you have to get rid of it still.

[FreeThinker]

*NOT* 5.7 m^2. IF you use that value, Plasma Thrusters will be over 101 times more vulnerable to atmospheric compression than they should be, and will stop producing thrust at a much higher altitude (coming down from orbit) than they should

you misunderstand me, for me the 5.7 variable is just a means to an end. The desired result is a -5.7 effect of thrust at sea level, since KSP Api returns exactly 1 at sea level, 5.7 is the number that gives me the desired result. To prevent confusion, I will divide the number by 101.325 ...

I updated the part files with your 0.85 approximation

Edited February 7, 2015 by FreeThinker

[Northstar1989]

OK, so the closest approximation I could find to the nozzle size/shape of one of the ATTILA Thrusters was one of the 4 nozzles of the NovaPunch2 Basic Berth Mini-Quad (meaning it will have 1/4th the Exit Area)

Stats for the NP2 BBMQ at Tech Level 7 in RealFuels:

Vacuum Thrust: 175.9874 kN

Vacuum ISP: 332.9 seconds

Sea-Level Thrust: 144.5856 kN

Sea-Level ISP: 273.5 seconds

Exit Area (4-nozzle NPBBMQ) = (175.9874 kN - 144.5856 kN) / 101.325 kPa = 0.3099 m^2

Exit Area (1.25 meter ATTILA) = 0.3099 / 4 = 0.0775 m^2

Which means the Exit Area value for the 0.625 meter ATTILA should be 0.0194 m^2 (1/4th as large)

The Thermal Rocket Nozzles:

This one is probably going to surprise you. The closest approximations I could find to the nozzle shape/size of the Thermal Rocket Nozzles were the nozzles of Solid Rocket Boosters...

This is a NovaPunch2 Advanced Segmented Solid Booster in RealFuels at Tech Level 7. The RT-10 Booster was also a close approximation to the 1.25 meter Thermal Rocket Nozzle, but in RealFuels the RT-10 is intentionally given below-average cost and performance for a SRB of that size to reflect shoddy manufacturing and fuel-packing...

NovaPunch2 Advanced Segmented Solid Booster Performance at Tech Level 7 in RealFuels:

Vacuum Thrust: 3600 kN

Vacuum ISP: 290 seconds

Sea-Level Thrust: 3289.65517241 kN

Sea-Level ISP: 265 seconds

Exit Area (NPASSRB) = (3600 kN - 3289.655 kN) / 101.325 kPa = 3.062865 m^2

The Thermal Rocket Nozzle has a *slightly* smaller nozzle though, so I round down for a nice, clean Exit Area:

Exit Area (2.5 meter Thermal Rocket Nozzle) = 3.06 m^2

This means that:

Exit Area (1.25 meter Thermal Rocket Nozzle) = 0.7657 m^2

Exit Area (3.75 meter Thermal Rocket Nozzle) = 6.891 m^2

As I pointed out before, the same equation describes the sea-level vs. vacuum performance of the Thermal Rocket Nozzles as does the performance of the Plasma and ATTILA Thrusters...

Regards,

Northstar

Edited February 7, 2015 by Northstar1989

[Northstar1989]

Also, not your problem, but I didn't give an Exit Area value for the Magnetic Nozzle yet because it's currently bugged with RealFuels installed, and getting that fixed is a higher priority for me... (plus, I have to go work a couple volunteer-shifts at my local Emergency Department in real life)

As you can see, it's trying to use Kerosene, rather than Charged Particles, as its fuel...

Regards,

Northstar

[Tirello]

Freethinker I like the work you do. It has made interstellar a great experience.

Your extended configuration shows its listed on ckan but I can't locate it there.

[FreeThinker]

Unless it causes problems with engines, why not see about bumping down the storage for thermal power and megajoules?

Well the problem is that I needs this amount to store the energy that is produced by an antimatter reactor in a single frame (1/20 of a second) at maximum warp (100000x time acceleration), which is a 5 GigaWatt!! By now I know how to adjust this to just enough for all reactors, but would still fundamentally flawed because why would it need so much storage just to produce power during high warp? That's why I want to match energy usage to energy production, so that you can never use power more power than is actually produced. It's a huge glaring inconsistency which most people seem to overlook, but a 5000 MegaWatt battery with infinite response time and 100% efficiency is simply not very realistic.

- - - Updated - - -

Freethinker I like the work you do. It has made interstellar a great experience.

Your extended configuration shows its listed on ckan but I can't locate it there.

I don't understand either, I must be doing something wrong. I asked for help at the CKAN forum but they ignored me. Could you help me? I know I would automatically be listed whn hosted at Kerbalstuff but obviously it isn't that simple. Perhaps I should make a stand alone download, that would no longer require you to download Boris Hosting...

Edited February 7, 2015 by FreeThinker

[FreeThinker]

OK, so the closest approximation I could find to the nozzle size/shape of one of the ATTILA Thrusters was one of the 4 nozzles of the NovaPunch2 Basic Berth Mini-Quad (meaning it will have 1/4th the Exit Area)

http://i.imgur.com/N0674XN.jpg

Stats for the NP2 BBMQ at Tech Level 7 in RealFuels:

Vacuum Thrust: 175.9874 kN

Vacuum ISP: 332.9 seconds

Sea-Level Thrust: 144.5856 kN

Sea-Level ISP: 273.5 seconds

Exit Area (4-nozzle NPBBMQ) = (175.9874 kN - 144.5856 kN) / 101.325 kPa = 0.3099 m^2

Exit Area (1.25 meter ATTILA) = 0.3099 / 4 = 0.0775 m^2

Which means the Exit Area value for the 0.625 meter ATTILA should be 0.0194 m^2 (1/4th as large)

I have implemented your values for ATTILA in my current download, but I think we are missing something in our calculation because following our current logic, the most effective thruster in the atmosphere would be thruster with a ExitArea the size of an atom. Even-though this would theoretically reduce loss by ExitArea close to 0 (0.000000001 * 1), it obviously not be a very realistic. What we are missing is some nozzle efficiency curve which determines the efficiency of a nozzle in Vacuum at minimim and maximum trust. I have actually already partially implemented something like this (called powerTrustMultiplier) which could correct partly this problem. For balancing reasons, I used it in KSP Interstellar Near Future Integration to improve the efficiency of larger thrusters (which are significantly heavier). But since that power of thrusters now grows twice as fast as it's exit area, smaller thruster become less efficient (at maximum trust) compared to the larger brethren. To compensate, we might want to give smaller thrusters at maximum trust a tiny trust/ISP efficiency bonus.

Edited February 7, 2015 by FreeThinker

[Vejur]

I recently picked up this game and mod again after being away for awhile. The upgraded computer core in boris' kspi maintenance mod behaves quite differently from what I remember when playing months ago, and I can't find any documentation related to my issues. Specifically:

1. AGI science is not automatically transferred to the science pool when making the core my active vessel, it needs to be manually transmitted or the core needs to be returned to Kerbin.

2. AGI science accumulates much more rapidly while the core is the active vessel (4x faster from what I have seen).

3. AGI science has diminishing returns.

Are these changes intended? I could understand #1 and #3, but it seems weird that my cores would generate science more slowly while out of focus, especially since science labs generate science at the same rate out of focus and in focus.

[ABZB]

Also, not your problem, but I didn't give an Exit Area value for the Magnetic Nozzle yet because it's currently bugged with RealFuels installed, and getting that fixed is a higher priority for me... (plus, I have to go work a couple volunteer-shifts at my local Emergency Department in real life)

http://i.imgur.com/4CQJr4n.jpg

As you can see, it's trying to use Kerosene, rather than Charged Particles, as its fuel...

Regards,

Northstar

The need for chargedparticles isn't an explicit fuel - that is all in the magnetic nozzle code itself. Realfuels has an MM patch somewhere in the folder that switches anything using liquidfuel that doesn't get a custom engine config to use kerosene. You can either edit the MN engines to LqdHydrogen directly (also switch all the other LF stuff to LqdHydrogen then) or use a MM patch to do so.

@PART[*]:HAS[@RESOURCE[Oxidizer]]:BEFORE[RealFuels]
{
	@RESOURCE[Oxidizer]
	{
		@name = LqdOxygen
	}
}

@PART[*]:HAS[@RESOURCE[LiquidFuel]]:BEFORE[RealFuels]
{
	@RESOURCE[LiquidFuel]
	{
		@name = LqdHydrogen
	}
}

@PART[*]:HAS[@MODULE[InterstellarMagneticNozzleControllerFX]]:BEFORE[RealFuels]
{
	@MODULE[ModuleEngines*]
	{
		@RESOURCE[LiquidFuel]
		{
			@name = LqdHydrogen
		}
	}
}

@PART[*]:HAS[@RESOURCE[Ammonia]]:BEFORE[RealFuels]
{
	@RESOURCE[Ammonia]
	{
		@name = LqdAmmonia
	}
}

@WARP_PLUGIN_SETTINGS:FOR[RealFuels]
{
	@HydrogenResourceName = LqdHydrogen
	@OxygenResourceName = LqdOxygen
	@AmmoniaResourceName = LqdAmmonia
}

Edited February 8, 2015 by ABZB

[etmoonshade]

Well the problem is that I needs this amount to store the energy that is produced by an antimatter reactor in a single frame (1/20 of a second) at maximum warp (100000x time acceleration), which is a 5 GigaWatt!! By now I know how to adjust this to just enough for all reactors, but would still fundamentally flawed because why would it need so much storage just to produce power during high warp? That's why I want to match energy usage to energy production, so that you can never use power more power than is actually produced. It's a huge glaring inconsistency which most people seem to overlook, but a 5000 MegaWatt battery with infinite response time and 100% efficiency is simply not very realistic.

Ack. I didn't know there was a limitation that was that bad. An interesting problem to solve, though.

Hmmmm. Is there a way to tweak capacity on the fly based on time warp? So at 1x or 100000x, either way, you've got a frame worth of MJ storage available? I guess the only problem there is that when going from high to low warp, you lose all that "extra" power that was generated - something gets wasted. In the grand scheme of things though, it's probably not all that bad - certainly not as bad and/or wasteful as running at 100% power all the time.

[FreeThinker]

The Thermal Rocket Nozzle has a *slightly* smaller nozzle though, so I round down for a nice, clean Exit Area:

Exit Area (2.5 meter Thermal Rocket Nozzle) = 3.06 m^2

This means that:

Exit Area (1.25 meter Thermal Rocket Nozzle) = 0.7657 m^2

Exit Area (3.75 meter Thermal Rocket Nozzle) = 6.891 m^2

As I pointed out before, the same equation describes the sea-level vs. vacuum performance of the Thermal Rocket Nozzles as does the performance of the Plasma and ATTILA Thrusters...

Regards,

Northstar

I'm getting some weird result,which do not seem right but are consistent with my data. A 2.5 Fusion reactor (5.1 GW Thermal power ) with thermal noozle only produces 389.4 kN in Space.

When I try to predic the maximum thrust using our formula and data I get the following result:

Max Thurst = Vacuum Thrust - (exitArea * Pressure)

389.4 - (3.06 * 101.325 * 1.0) = 389.4 - 310.05 kN = 79.35 kN .This would mean the 2.5 Thermal Thruster connected to a Advanced Fussion Engine would lose almost 80% Thrust and ISP at sea level.

Now the measured Thrust is even worse 17.7 kN but not that far from what I predicted

Obviously, something is not right here!

Edited February 8, 2015 by FreeThinker

[Atrius129]

I asked for help at the CKAN forum but they ignored me. Could you help me?

Doesn't it suck when that happens?

So I am trying make some quantum vacuum RCS thrusters (As per Angel-125's apparently abandoned project):

MODULE

{

name = ModuleRCS

thrusterTransformName = RCSthruster

thrusterPower = 1

resourceName = ElectricCharge

resourceMass = 0.0001

atmosphereCurve

{

key = 0 260

key = 1 100

}

}

This actually semi works, the problem being all EC is totally drained and refilled extremely rapidly. I built a tiny probe with several thousand EC + 1.25 fusion reactor and gene + 8 QV RCS thrusters. It seems that no matter how much battery life there is it is instantly drained by the thrusters and refilled by the fusion reactor. This switches off SAS but RCS remains on. I know the issue is probably that EC has none of the weight that is being called for and instead should be some type of resource per second rate. I guess the Quantum Vacuum (or MJ) resource would be better to use than EC. Any help to get this resolved would be greatly appreciated.

Ultimately I would like to continue with his repulsor idea that would allow large craft to translate easily using the RCS commands.

[Northstar1989]

I have implemented your values for ATTILA in my current download, but I think we are missing something in our calculation because following our current logic, the most effective thruster in the atmosphere would be thruster with a ExitArea the size of an atom. Even-though this would theoretically reduce loss by ExitArea close to 0 (0.000000001 * 1), it obviously not be a very realistic.

Obviously having an Exit Area the size of an atom is unrealistic (who could manufacture an aperture than small?) but it's actually accurate in that such an opening would experience *absolutely no* atmospheric compression (how could it be compressed further- it's already only an atom wide!)

What you are missing is the trade-off between sea-level ISP and vacuum ISP. Having a larger nozzle improves vacuum ISP, and actually up to a certain point can improve sea-level ISP as well, as vacuum ISP is a term in the equation for sea-lvel thrust (which equation I've posted several times now). Increased atmospheric compression (due to reduced Exhaust Pressure) is just the price you pay for the higher Exhaust Velocity... However, the effect of the nozzle size is already assumed to be present in the current parts- with a smaller nozzle the electric/thermal thrusters would have lower ISP and produce less thrust in vacuum for the same power/propellant consumption than they currently do.

I brought up the subject of creating alternative Thermal Rocket Nozzle parts that are optimized for different atmospheric densities before (lower atmosphere, upper atmosphere, and vacuum- in order of increasing nozzle sizes), much like there are currently a variety of chemical rockets with different nozzle designs for different conditions. The versions with larger nozzles would have a higher vacuum ISP for the same power-level and propellent choice, but would have a higher mass and a larger Exit Area (and pay a larger penalty in atmospheric-compression as a result).

What we are missing is some nozzle efficiency curve which determines the efficiency of a nozzle in Vacuum at minimim and maximum trust. I have actually already partially implemented something like this (called powerTrustMultiplier) which could correct partly this problem. For balancing reasons, I used it in KSP Interstellar Near Future Integration to improve the efficiency of larger thrusters (which are significantly heavier). But since that power of thrusters now grows twice as fast as it's exit area, smaller thruster become less efficient (at maximum trust) compared to the larger brethren. To compensate, we might want to give smaller thrusters at maximum trust a tiny trust/ISP efficiency bonus.

That's completely inaccurate (and you might want to change it up in your NearFuture config). A nozzle design doesn't work differently at high or low thrust- it is always subject to the SAME atmospheric compression, and always increases the vacuum ISP by the SAME proportion.

How a nozzle can be *optimized* for a given thrust-level without working differently is that if you have a higher thrust you can more afford to pay the penalty of a larger Exit Area and gain more kN of extra thrust from the higher vacuum ISP (for instance, a given nozzle might increase the vacuum ISP of an engine by 10%, but weight 100 kg and incur 24 kN of atmospheric-compression. If the thrust is high enough, the extra thrust from a higher vacuum ISP will outweigh the thrust penalty from atmospheric-compression and the TWR penalty from the extra nozzle mass...)

One final, important note:

I said before that you needed to divide the atmospheric-compression thrust-loss by Background Pressure in terms of kiloPascals (101.325 kPa) in order to have Exit Area in terms of square-meters. However, what I forgot is that KSP already expresses atmospheric-density as a fraction of Earth/Kerbin sea-level (so 101.325 kPa = 1, 202.65 kPa = 2, and so on...) So, the *easiest* and best way to correct for atmospheric compression might indeed be to utilize an "Exit Area Factor" equal to the kN of thrust lost at 1 atmosphere of pressure, like you had before. However, if so the process for calculating atmospheric-compression needs to look like this...

(1) Game calls up atmosphere-density, which is normally stored as a fraction of Kerbin sea-level in stock KSP... (so, 5 at Eve sea-level, 1 at Kerbin sea-level, and 0.2 on Duna)

(2) Game multiplies this number by the "Exit Area Factor" which is equal to the kN of thrust lost at 1 atmosphere of pressure (so EAF = 5.7 kN/atmospheres)

(3) Game subtracts the number form step #2 from the thrust the engine would normally produce in vacuum at this throttle-level, etc.

THAT is the simplest and easiest way to correctly calculate sea-level thrust (and thus adjust sea-level ISP compared to vacuum), from a coding perspective.

Regards,

Northstar

- - - Updated - - -

I'm getting some weird result,which do not seem right but are consistent with my data. A 2.5 Fusion reactor (5.1 GW Thermal power ) with thermal noozle only produces 389.4 kN in Space.

When I try to predic the maximum thrust using our formula and data I get the following result:

Max Thurst = Vacuum Thrust - (exitArea * Pressure)

389.4 - (3.06 * 101.325 * 1.0) = 389.4 - 310.05 kN = 79.35 kN .This would mean the 2.5 Thermal Thruster connected to a Advanced Fussion Engine would lose almost 80% Thrust and ISP at sea level.

Now the measured Thrust is even worse 17.7 kN but not that far from what I predicted

Obviously, something is not right here!

Actually, that's *EXACTLY* how it should be.

Think about it- the tiny, 0.625 meter Plasma Thruster loses around 14% of its thrust when accepting a full 3.125 GW of power.

The 2.5 meter Thermal Rocket Nozzle is not just a part with a 4 times larger diameter-base (which means a 16 times larger Exit Area even with the same nozzle design), it also has a much larger nozzle design relative to that base. In fact, its nozzle area is nearly 4 times larger relative to the diameter of the rocket- 63.75 times larger in all!

So, now, you're expanding only a little under twice the Thrust into almost 64 times the nozzle area. What do you think happens to the Exhaust Pressure for a rocket like that? Lower Exhaust Pressure means higher Atmospheric-Compression (the basic mechanism of atmospheric-compression of rocket exhaust is that it compresses the exhaust stream until it reaches the same pressure as its surroundings...)

If you want a more reasonable performance at sea-level, DON'T try and use Hydrogen- even with a Fusion Reactor. Try using Methane instead (which has 8 times the molecular mass). If RealFuels is installed (I forget in Methane has an accurate ISP and Thrust compared to LiquidFuel *without* RealFuels installed...) you should get 1101.4 kN of thrust in vacuum, and 791.3 kN of thrust at sea-level (almost 72% as much thrust- which is quite impressive sea-level performance for an engine with that high an ISP!)- more than enough to get a small rocket off the ground at that ISP-level, if that's what you're aiming for...

Nuclear Thermal Rockets aren't really designed for atmospheric use anyways- they're designed for vacuum (they're basically more modern versions of NERVA). A Thermal Rocket Nozzle attached to a Fusion Reactor produces *MUCH* less thrust at a far greater Specific Impulse than the same amount of power does when you use Microwave Beamed Power (under-the-hood, the game considers a Thermal Receiver to have a lower "reactor temperature" and instead divides up the same energy over more mass for higher Thrust but lower ISP...) Try beaming 5 GW of power to a Thermal Rocket Nozzle and THEN complain to me about how something doesn't seem balanced right...

Regards,

Northstar

P.S. Don't forget what I wrote earlier. It may actually make the game run a little faster (and will certainly make your code easier to understand) if you keep the Exit Area Factor in terms of kN/atm instead of m^2, so KSP doesn't have to do a unit-conversion of atmospheric pressure to kPa every time it needs to calculate engine thrust in-atmosphere... You were on the right track originally with using 5.7 for the 0.625 meter Plasma Thruster, etc.- sorry for not seeing that... To get the Exit Area Factors for all the engines I listed earlier, just multiply the Exit Area in m^2 by 101.325...

Edited February 8, 2015 by Northstar1989

[FreeThinker]

I recently picked up this game and mod again after being away for awhile. The upgraded computer core in boris' kspi maintenance mod behaves quite differently from what I remember when playing months ago, and I can't find any documentation related to my issues. Specifically:

1. AGI science is not automatically transferred to the science pool when making the core my active vessel, it needs to be manually transmitted or the core needs to be returned to Kerbin.

2. AGI science accumulates much more rapidly while the core is the active vessel (4x faster from what I have seen).

3. AGI science has diminishing returns.

Are these changes intended? I could understand #1 and #3, but it seems weird that my cores would generate science more slowly while out of focus, especially since science labs generate science at the same rate out of focus and in focus.

point #2 sounds a bug, my first guess is that it has something to do with KSPI assumption that a day is like an earth day, which it is, not because a kerbin day is 4 times as short.

Edit: Yep, I was right, it uses EARH_DAY_SECONDS (86400) time instead of KEBRIN_DAY_SECONDS (21600). I kave fixed it in version 0.5.6 and can be downloaded from KerbalStuff.

Edited February 8, 2015 by FreeThinker

[FreeThinker]

Actually, that's *EXACTLY* how it should be.

Yes but it now seems the Thermal nozzle connected to a Fusion reactor get's screwed by its of high ISP (3398), causing low trust (389.4 kN) which is barely sufficient to overcome atmospheric pressure @ Kerbin surface. At least for thermal noozles there might be some justification to partially convert a ISP into trust and then apply our atmospheric presume effects.

Another problem might be that KSPI Thermal Noozles produce too little thrust in General. Just take a basic small nuclear reactor (1.25m) for example which combined with a thermal noozle produces much less power (8.75 kN) that an equivalently sized stock nuclear thruster (60 kN). In my own KSP Interstellar Near Future Integration I correct this by making the conversion from heat into trust much more efficient. But I kept wondered if there is any basis for this large difference in perforce in the real world.

- - - Updated - - -

Don't forget what I wrote earlier. It may actually make the game run a little faster (and will certainly make your code easier to understand) if you keep the Exit Area Factor in terms of kN/atm instead of m^2, so KSP doesn't have to do a unit-conversion of atmospheric pressure to kPa every time it needs to calculate engine thrust in-atmosphere...

No it won't give any "performance" advantages, it just another simple multiplication, part of a much more complex calculation which is something a PC is really good at (it can use both L1 cache and pipelining). Also it's trivial for code complexity, it actually makes the code clearer since it now uses real world quantity (m2) which everybody can understand instead of a slight more convenient (kN/atm). Besides, I already have released several versions, it would cause backward incompatibility issues if I switched back. Edited February 8, 2015 by FreeThinker

[Olympic1]

I updated my CTT config for KSPI. Thank you FreeThinker for the requests.

Download

Changes:

* Moved all the Magnetic Nozzles from Advanced Plasma Propulsion to High Efficiency Nuclear Propulsion.

* Moved the FNFissionFusionCatReactor from High Energy Science to Exotic Reactions.

Edited February 8, 2015 by Olympic1
Fix

[FreeThinker]

Moved all the Magnetic Nozzles from Advanced Plasma Propulsion to High Energy Nuclear Power.

Actualy I requested Magnetic Nozzles to be moved to High Efficiency Nuclear Propulsion, since it's a Nuclear Propulsion technology!

Edited February 8, 2015 by FreeThinker

[Olympic1]

Actualy I requested Magnetic Nozzles to be moved to High Efficiency Nuclear Propulsion, since it's a Nuclear Propulsion technology!

fixed (10char)