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Boris-Barboris

[0.90] KSP Interstellar port maintance thread

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This will take me some time to realize, but I have had enough practice ;)

OK, if it helps any, I can get you a new value for the Thrust/MW as well, just so long as I have a couple values at known Specific Impulses, Thermal Powers, and Exhaust Temperatures... What was the Exhaust Temperature (found by right-clicking on the reactor, or maybe nozzle, as "Heat Exchanger Temperature") at the precise moment you got that Thrust value before?

The best way for me to figure this out would be to launch a suborbital rocket (for ease, you don't need to circularize, just make it above the atmosphere...) and fire off any 1 of the unupgraded gen fission reactors with two different fuel types (say LiquidFuel/Hydrogen, and Methane) and take a screenshot wit the context menu for the reactor or nozzle visible in each situation so I can get precise value for the Exhaust Temperature and Thrust at an exact moment in time...

It might also be helpful to have data for one each of the Molten Salt Reactors and Pebble Bed Reactors (isntead of 2 different fuel types, but launching such a rocket is a little bit harder), to confirm Thrust/MW is (as I suspect) coded as a function of the Thermal Rocket Nozzle and not somehow of the reactor type...

Regards,

Northstar

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The Thermal Rocket Nozzle currently uses the function:

ISP = 17 * SqRt (Exhaust Temperature)

Where does the 17 number from? I'm very familiar with the number you mean but, the number used in Boris KSPI version is 22.371670613. I know because I made it configurable with the setting IspCoreTempMult in warpPluginsetting.cfg. In KSP Interstellar Near Future Integration I put it at 20, to make calculation easier and to allow lower core temperatures. It allowed me to give a basic Near future reactor exacly 60 kN of trust.

- - - Updated - - -

The best way for me to figure this out would be to launch a suborbital rocket (for ease, you don't need to circularize, just make it above the atmosphere...) and fire off any 1 of the unupgraded gen fission reactors with two different fuel types (say LiquidFuel/Hydrogen, and Methane) and take a screenshot wit the context menu for the reactor or nozzle visible in each situation so I can get precise value for the Exhaust Temperature and Thrust at an exact moment in time...

Actualy, I use a much quiker method, specificly I use th simulation mode in Kerbal Construction Time. It saves me a lot of time as it put my testing vessel directly in a orbit around Kerbin ;)

Edited by FreeThinker

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- Reduce all reactor masses by 75% (to 1/4th their current values). Reduce Thermal Rocket Nozzle masses by 75% as well (will still lead to a slightly heavier reactor+nozzle pair than in real life.)

I think I prefer to keep them the same. We can justify their high weight by their strong radiation shielding (no effects), long endurance (infinite), propellant versatility (10+) and their ability hook up to an electric generator. Later me might add a VAB configuration that allow lighter versions at the expense of reduced endurance and versatility, radiation shielding and limited utility, but for now limit choice to the weight chosen by Fractal.

Edited by FreeThinker

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That won't actually be a large enough increase in Thermal Power to get a TWR of 30 if you also up-rate the reactor temperature to something closer to the real-world value (3000 K) so that the Vacuum ISP will be closer to the real-world values as well. Currently the Vacuum ISP at full-throttle using Hydrogen is only 582.3 seconds instead of more than 1000 (the Timberwind 75 design had 1000 seconds, but our version has a relatively larger nozzle and should have a better vacuum ISP as a result...)

None of those Thermal Power ratings will be high enough with an increase in the reactor temperature either...

Why? I rather like the idea of having a nozzle that is large enough for vacuum-usage. If we just give the ISP-calculation a little nudge in the right direction we can make the Vacuum ISP reflect the current nozzle size... (see my post above: we should change the coefficient from 17 to 21 to get a 15% increase in Vacuum ISP) Currently the calculation actually gives *too low* a Vacuum ISP for given reactor temperature- for instance a 3000 K Timberwind reactor had a Vacuum ISP of 1000 seconds, but the same temperature reactor only gives about 931 seconds in KSP-Interstellar...

NorthStart, :P

Have you looked at the SNTP report (I think it's a follow up program to Timberwind)?http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA305996

Their engine had an ISP of 930, and TWR=20 without shielding. With internal shielding (not enough shielding for a manned rocket), their TWR was more like ~10-16. It also states that a partial-flow expander cycle could improve the ISP to 960 sec. at 2870K.

The fission reactors have minimum output settings (25%?), and can only be activated or shut down by Kerbals, right? With your power increases, will this shorten the longevity of a fission powered probe, or will you increase the fuel stored in the reactor?

Also, thanks for all the work you and FreeThinker have done on this!

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Got a new problem, just reached Advance Fusion Power and Experimental Electrics but my Radiators, Thermal Turbojets, and Generators do not upgrade. Regular Fusion Reactors do upgrade (Though the AIM reactor doesn't... does that upgrade with Antimatter Reactors?). Tried upgrading to KSPI Extended 0.5.7 to no effect. Does this have something to do with CTT? (think I read something about that several pages ago.)

Any help would be appreciated... hoping to launch to Duna tonight.

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NorthStart, :P

Have you looked at the SNTP report (I think it's a follow up program to Timberwind)?http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA305996

Their engine had an ISP of 930, and TWR=20 without shielding. With internal shielding (not enough shielding for a manned rocket), their TWR was more like ~10-16. It also states that a partial-flow expander cycle could improve the ISP to 960 sec. at 2870K.

The fission reactors have minimum output settings (25%?), and can only be activated or shut down by Kerbals, right? With your power increases, will this shorten the longevity of a fission powered probe, or will you increase the fuel stored in the reactor?

Also, thanks for all the work you and FreeThinker have done on this!

No, I have not taken a look at the SNTP report. The SNTP program never got nearly as far along as the Timberwind program, and as such their data is much less trustworthy. I guess that means the current mass and TWR figures are more reasonable than expected, but the lower ISP than Timberwind can only mean they had a lower operating-temperature (especially since they probably also had a larger rocket nozzle). If there's any uncertainty I'm strongly inclined to err on the side of Timberwind, since once again, their program made it much further along. It's also reasonable to assume that if KSP-I reflects current or slightly-futuristic technology, the reactor core temperatures possible would have at least stayed the same since Timberwind- which is all that is needed for the 1150 second Vacuum ISP with the vacuum nozzle (and the changes to the ISP code).

@FreeThinker

I got the 17 * SqRt (Exhaust Temp) number from the R&D screen view of the Thermal Rocket Nozzle in my current game.

I'm running a slightly older version of the Extension Config (0.4.1) in this save, as I haven't gotten around to updating it yet (and am waiting for the addition of CarbonDioxide to the list of storable resources in RealFuels/Procedural Parts tanks before I do... I asked you about that some time ago- how are we doing on that? A universal tank is nice, but players using RealFuels and/or Procedural Parts are still going to want to be able to store CO2 in the respective tank types... Also, CO2 isn't listed as a Thermal/Electric propellant in the KSP-I Extension Config changelog yet, though I gave you the ISP/Thrust figures you need for that a while back as well...)

Did you change the ISP calculation in KSP-I+Extension Config (I don't have anything to do with NearFuture except for the solar panels) since 0.4.1? If not, are you sure that you really changed the formula before? I'm more inclined to go with the formula I see in-game than any changes you attempted to code in before, as the code changes might not have taken hold...

I just unlocked NTR's in my current Career save (the one I've been testing in). I'll be testing them in extra-atmospheric conditions some time soon, and will be able to report on what the current Thrust/MW rating is for Thermal Rockets, and what it needs to be to accurately reflect real life with a rocket nozzle this size... (note that the changes also affect Microwave Thermal Rockets- which apparently also produce too little Thrust/MW, as the current relationship is wrong universally for all Thermal Rockets)

Regards,

Northstar

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I keep getting " Warning: Fusion Reactor plasma heating cannot be guaranteed, reducing power requirements is recommended.'' I dont know how to fix this can someone help?

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"Sethlans" 1.25m Particle Bed Reactor- 187.5 MW (currently 85 MW)

"Sethlans 2" 2.5m Particle Bed Reactor- 1800 MW (currently 770 MW)

"Akula" 3.75m Particle Bed Reactor - 6400 MW (currently 4500 MW)

Ok, I can understand the 2.5m version is 9.6 times as powerfull as the 1.25 version (which is 8 times in size) but I can't understand why the 3.75 version should be 3.56 times as powerfull as the 2.5m version. I understand with larger size allow you to concentrate more power, but I would not expect it to grow faster as you increase in volume. I would expect the Akula 3.75m to be (9.6 /8 * 2 = ) 2.4 times as powerfull as 2.5m version = 4320 MW

At least the picture becomes more understandable if we look at the mass. The 2.5m Sethan mass is 9.5 ton while the Akula mass is 29 ton which is a bit bore than 3 times a heavy! Still by looking at the physicial size, I wouldn't expect the Akula not to weight more than 19 ton, where does the 10 extra ton come from?

- - - Updated - - -

I keep getting " Warning: Fusion Reactor plasma heating cannot be guaranteed, reducing power requirements is recommended.'' I dont know how to fix this can someone help?

Well usualy it has something to do with not having any (radiators) cooling

- - - Updated - - -

(Though the AIM reactor doesn't... does that upgrade with Antimatter Reactors?).
Yes, you need antimatter technology to upgrade

- - - Updated - - -

I got the 17 * SqRt (Exhaust Temp) number from the R&D screen view of the Thermal Rocket Nozzle in my current game.

Well don't rely on that number to be true. The Editor information is calculated seperate from the real calculations and are currenyly unreliable.

- - - Updated - - -

Did you change the ISP calculation in KSP-I+Extension Config (I don't have anything to do with NearFuture except for the solar panels) since 0.4.1?

No I didn't, I only made all constants configurable and added additional configsetting (which default to its original value, 1 or 0) to tweak the ISP and trust values. Technically by changing the variables in the config files and part files you should already be able to get any results you want. It would save me al lot of time allowing me to concentrate on the code instead of numbers.

- - - Updated - - -

I'm running a slightly older version of the Extension Config (0.4.1) in this save, as I haven't gotten around to updating it yet (and am waiting for the addition of CarbonDioxide to the list of storable resources in RealFuels/Procedural Parts tanks before I do... I asked you about that some time ago- how are we doing on that? A universal tank is nice, but players using RealFuels and/or Procedural Parts are still going to want to be able to store CO2 in the respective tank types... Also, CO2 isn't listed as a Thermal/Electric propellant in the KSP-I Extension Config changelog yet, though I gave you the ISP/Thrust figures you need for that a while back as well...)

I highly advice you update to the latest version at all times, otherwise we risk even more confusion and it allows me to verify my work. I had put my work on the universal configurable crystat at hold (for the Athmosphere Fix) but I think should prioritise it again. It should allow KSPI players to use any KSPI resource (including liquid CO2) and configure its contents inside/outsite the VAB after you empty it. It will effectely be a Modula Fuels Light,

Edited by FreeThinker

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Hi Boris..

First of all.. Thanks for continue with this awesome mod..

I back to kerbal.. and try to update to 0.90..

New installation and only KSPI

But.. microwave receiver no run.. .really i dont´t know if something change..

I add microwave trans.. but when we want activate the module.. no animation,, and say .enable.. but no energy flow..

It´s a know issue?

I do something worng???

Thanks in advance

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The fission reactors have minimum output settings (25%?), and can only be activated or shut down by Kerbals, right? With your power increases, will this shorten the longevity of a fission powered probe, or will you increase the fuel stored in the reactor?

The short answer is yes, if you increase heat output, you also increase nuclear fuel consumption and produce more waste heat. We can compensate by adding higher fuel reserves, it would make overal weight of reactors heavier and require additional radiators for cooling. Fuel weight is already a significant part of the overal weight of a reactor. To keep life expectancy the same, the fraction a reactor is increased in Heat production should also be done with they fuel storage. Perhaps this will solve our (to low) Mass problem, as we reduce empty reactor weight and increase fuel storage, the end weight (including radiators) would be roughly the same (with the option to reduce overal weight by not filling up the fuel storage and minimise radiators). I'm thinking about including (RealFuel) LiquidHydrogen & Oxygen by default, I already did for the NTR/Plasma Engines, this should allow us to finaly get rid of the LiquidFuel/Oxidiser fuels

Btw, radiators is something we should take a much better look at. The amount of waste heat radiators can store in KSPI is huge and it requires many days before a reactor (at full power) reaches an balance with installed radiators. Somehow this seems wrong it should be drasticly reduced.

Edited by FreeThinker

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I had put my work on the universal configurable crystat at hold (for the Athmosphere Fix) but I think should prioritise it again. It should allow KSPI players to use any KSPI resource (including liquid CO2) and configure its contents inside/outsite the VAB after you empty it.

Yes, please. That would be an excellent addition to what is already a great mod. Thank you, FreeThinker, for the work you put in. I can see that you have a lot on your plate :)

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Ok, I can understand the 2.5m version is 9.6 times as powerfull as the 1.25 version (which is 8 times in size) but I can't understand why the 3.75 version should be 3.56 times as powerfull as the 2.5m version. I understand with larger size allow you to concentrate more power, but I would not expect it to grow faster as you increase in volume. I would expect the Akula 3.75m to be (9.6 /8 * 2 = ) 2.4 times as powerfull as 2.5m version = 4320 MW

At least the picture becomes more understandable if we look at the mass. The 2.5m Sethan mass is 9.5 ton while the Akula mass is 29 ton which is a bit bore than 3 times a heavy! Still by looking at the physicial size, I wouldn't expect the Akula not to weight more than 19 ton, where does the 10 extra ton come from?

The 3.75 meter "Akula" is actually 1.5 * 1.5 * 1.5 = 3.375 times larger than the "Sethlans 2". Remember, parts grow in all 3 dimensions. That is why I've repeatedly stated that the "Sethlans" reactor only has about 1/4th (23.3%, to be precise) the volume of the Timberwind 75, despite having 62% (1.25/2.03 m) the diameter and 38% (1.5625/4.1209 m^2) the cross-sectional area...

Thus, the Akula sees a *MUCH SMALLER* bonus for its scaling: 5.3% (6400/6075) vs. a 20% bonus for the "Setlhans 2" (1800/1500) compared to what you would expect simply from the relative-size compared to the next-smallest reactor. This reflects diminishing-returns from scaling up reactors.

The "Akula" is actually the *LIGHTEST* of the Pebble Bed Reactors on a ton-per-cubic-meter basis...

Well don't rely on that number to be true. The Editor information is calculated seperate from the real calculations and are currenyly unreliable.

That's nice to know. Would it be hard for your to fix that so it's accurate again? I'll soon be checking vs. the actual numbers, though, as I plan to vacuum-test a Sethlans and a SAFE-1500 or KIWI today...

No I didn't, I only made all constants configurable and added additional configsetting (which default to its original value, 1 or 0) to tweak the ISP and trust values. Technically by changing the variables in the config files and part files you should already be able to get any results you want. It would save me al lot of time allowing me to concentrate on the code instead of numbers.

Well I already gave you numbers to implement for the new Thermal Power ratings, and if the ISP constant was already changed to 22 in the Boris version (is this new to his version or from the vanilla Interstellar version- and where did you find out what the actual # being used in the calculation is?) then it doesn't need to be up-rated to 21 (I thought about suggesting 22 instead of 21, as the actual most realistic coefficient would be about 21.6, but decided to round down to stay conservative...)

Could you get the Thermal Power #'s I gave you implemented into the base code/ part configs? Meanwhile, I'll be working on some #'s for the adjustments to the Thrust/MW based on actual measured Thrust in vacuum (*especially* if the ISP-coefficient was already increased, this needs to be raised: otherwise you will be getting VERY low Thrust/MW compared to real life...) I would like to see the Thrust/MW values I come up with to match real life predictions added to the Extension Config defaults (or the base code) rather than being my own personal settings, obviously...

Also, please look into making the info in the R&D/VAB/SPH show up accurately. Players need accurate numbers in order to plan their missions correctly. If a player launches a rocket with a NTR upper-stage (like was proposed in real life for the Saturn V-N), only to discover his ISP is twice what the SPH predicted and his Thrust only half the prediction, he probably isn't going to make it into space that day... (he'll fall back into the atmosphere before he circularizes)

I highly advice you update to the latest version at all times, otherwise we risk even more confusion and it allows me to verify my work. I had put my work on the universal configurable crystat at hold (for the Athmosphere Fix) but I think should prioritise it again. It should allow KSPI players to use any KSPI resource (including liquid CO2) and configure its contents inside/outsite the VAB after you empty it. It will effectely be a Modula Fuels Light,

If I were testing anything that had been updated since 0.4.1, I would have been sure to have had the latest version. I've been going by the changelog to see when I need to update (which is also why I encourage you to keep the changelog complete+accurate, it doesn't even mention CO2 as a new Thermal/Electric resource, for instance...) Because I use Active Texture Management, any time I update KSP's mods the game takes a *LOT* longer to start the first time after, so I tend to delay it as long as possible...

Also, we still need a RealFuels and a Procedural Parts MM patch to allow CO2-storage.

Can I suggest you implement a solution something like the following code Dreadicon used to add the option to hold KSP-I LqdWater to any RealFuels tank type that can already hold Kerosene?


//Add water tank using KSPI water. (TO-DO: integration with TACLS water without trampling KSPI or TACLS)
@TANK_DEFINITION[*]:HAS[@TANK[Kerosene]&!TANK[LqdWater]]:NEEDS[WarpPlugin]:FOR[RealFuels]
{
+TANK[Kerosene]
{
@name = LqdWater
}
}

PLEASE NOTE: The "&" symbol is no longer a valid coding character in ModuleManager, and should not be used in any fix you create. It still needs to be replaced with a "," (comma) symbol, which will have the same intended function, in the release-version of RealFuels...

Just use the existing RealFuels "LqdMethane" (which replaces the KSP-Interstellar Methane when RealFuels is installed) as a reference for what can hold CO2- since any tank type that can hold liquid Methane should reasonably be able to hold liquid CO2 with a little modification...

After you come up with such a fix, submit a pull-request on the RealFuels "KSPI_RF" file that adds the changes, and that way RealFuels compatibility with the new KSP-I resource will be added from the RealFuels end...

Such a fix would also work for Procedural Parts when RealFuels is installed. To get it working without would require submitting a pull-request with a similar fix to the base (rather than RealFuels) version of the Procedural Parts mod though...

Regards,

Northstar

Edited by Northstar1989

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if the ISP constant was already changed to 22 in the Boris version (is this new to his version or from the vanilla Interstellar version- and where did you find out what the actual # being used in the calculation is?) then it doesn't need to be up-rated to 21 (I thought about suggesting 22 instead of 21, as the actual most realistic coefficient would be about 21.6, but decided to round down to stay conservative...)

No Fractal must have set the value to 22.371670613 himself, just take a look at the original KSPI code updated 4 months ago (look specificly to line 76):

https://github.com/FractalUK/KSPInterstellar/blob/master/FNPlugin/FNNozzleController.cs

also line 256 should be special intrest to you since it contains the used formula for calculating thrust (I highligted the significant part):


engineMaxThrust = Math.Max(thrust_limit * [B]2000.0 * thermal_power_received / maxISP / g0[/B] * heat_exchanger_thrust_divisor*ispratio/myAttachedEngine.currentThrottle,0.01);

So KSPI Vacuum is calculated by

ISP (Vacuum) = 2000.0 * thermal_power_received / maxISP / g0

now lets make some prediction based on the numbers you supplied for a Sethan (1.25):

ISP = 22.371670613 * Sqrt(3000) = 1225 s

Max Thrust = 2 *1000 * 187.5 MW / 1225 s / 9.82 = 31.17 kN

a bit disapointing,

fortunatly I have introduced a WarpPluginSetting called GlobalThermalNozzlePowerMaxTrustMult (default value 1)

if you want to achieve 105.728 kN, set the GlobalThermalNozzlePowerMaxTrustMult to 105.728 / 31.17 = 3,392

there is however is a problem that this will effect all existing ThermalNoozles in the game

fortunatly I have also introduced a module setting powerTrustMultiplier in FNNozzleController (default value 1)

this setting allows only new vessels (with newly added thermal nozzle part) to recieve the thrust bonus.

notice this part setting combined with ExitArea setting allow to create noozles optimised for several athmospheric conditions. Now If only a moddeler would be so kind to create some additional noozles, we could also offer a lot more choice!!

Except for new models, Modifying KSPI thrust never was so easy, now was it? :D

Edited by FreeThinker

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No Fractal must have set the value to 22.371670613 himself, just take a look at the original KSPI code updated 4 months ago (look specificly to line 76):

https://github.com/FractalUK/KSPInterstellar/blob/master/FNPlugin/FNNozzleController.cs

Interesting. It looks like Fractal_UK had some of the same thoughts we did, only 4 months ago... (we should still update the displayed calculation in R&D/SPH/VAB though...)

also line 256 should be special intrest to you since it contains the used formula for calculating thrust (I highligted the significant part):


engineMaxThrust = Math.Max(thrust_limit * [B]2000.0 * thermal_power_received / maxISP / g0[/B] * heat_exchanger_thrust_divisor*ispratio/myAttachedEngine.currentThrottle,0.01);

That's GREAT. But I'm not sure if you're reading the formula format correctly. Here's how I read it, based on already knowing what it SHOULD look like:

Engine Max Thrust = Math.Max [(* 2000 * thermal_power_received * heat_exchanger_thrust_divisor * ispratio * myAttachedEngine.currentThrottle, 0.01) / (MaxISP * g0)], thrust_limit

Note that Engine Max Thrust is the functionally equivalent to "Vacuum Mas Thrust", as an engine always produces max thrust in vacuum at full-throttle...

ISP * g0 = Exhaust Velocity, and Exhaust Velocity is normally found in the denominator of this type of Thrust calculation (Thrust = Thermal Power/ Exhaust Velocity), so that's why I assigned both terms (MaxISP and g0) to the denominator here...

The equation, as a whole, is clearly derived from E = 1/2 m v^2, solving for m*v, which is Thrust (mv = 2 * E / v = Thrust). Exhaust Velocity = "v", and E is in terms of Megawatts (so you have to convert it to kW by multiplying by 1000, if you want Thrust in kN- hence "2000" instead of "2" in Fractal_UK's equation..)

Now the question is, what do some of the other terms mean?

I'm GUESSING:

thrust_limit

Is normally a Thrust value (in kN). Reflects the maximum thrust that a Thermal Rocket Nozzle can produce. Somehow, Fractal_UK has figured it into the equation such that this # cannot be exceeded, likely using the "Math.Max" function... (which is why I placed it OUTSIDE the parentheses)

heat_exchanger_thrust_divisor

Is probably normally a number between 0 and 1, representing the *fractional efficiency* of a heat exchanger (so 50% = multiply by 0.5) Or, alternatively, a number in the denominator you divide by to the same effect (i.e. 50% - divide by 2). This is a real factor in thermal rocket design (not all Thermal Power is transferred to the propellant stream), I just had no idea Fractal_UK had integrated it into KSP-Interstellar... I don't know if this corresponds to the "fuel_efficiency" value on reactor parts, or is found somewhere else...

myAttachedEngine.currentThrottle

Looks like the Throttle Setting to me (which would be a value between 1 and 0.01) I haven't included it in all my previous calculations, but I've always assumed it would fit into the final equation for Thrust...

ispratio

This small, mysterious term *S PROBABLY THE MOST IMPORTANT OF ALL* for getting the correct value. I'm guessing that it represents the effect of the nozzle on the Thrust, that is the ability of a nozzle to amplify Thrust beyond (Thrust = Power/ Exhaust Velocity) to [Thrust = (Power/Exhaust Velocity) + (Exit Area + Exhaust Pressure)]. In short, I'm guessing this value holds the key to understanding the precise way Fractal_UK is converting Thermal Power to Thrust, and why your predictions probably won't match up with actual results... (see borrom)

I'm guessing "ispratio" is the whole-number ratio (so a value greater than 1) of vacuum Thrust based purely on (Mass Flow Rate * Throat Velocity) to actual Vacuum Thrust, which is (Mass Flow Rate * Exhaust Velocity). Note I use the term "Throat Velocity" to indicate the speed of the exhaust when it exits the rocket, and enters the nozzle; whereas "Exhaust Velocity" is the speed of the exhaust when it leaves the nozzle (which acts to accelerate the exhaust-stream by expanding it, at the expense of Exhaust Pressure and thus Atmospheric ISP...) That is, the ratio between the isp BEFORE the nozzle and AFTER the nozzle, which is exempt from the trade-off between ISP and Thrust normally seen with higher-temperature reactors vs. reactors with higher Thermal Power, as it serves to INCREASE Thrust *AND* ISP by the same factor...

Alternatively, "ispratio" could just be the ratio of Vacuum to Atmospheric ISP, using the stock ISP curve... (in which case it's a number between 0 and 1, and the Thrust/MW will be hopelessly inaccurate...)

So KSPI Vacuum is calculated by

ISP (Vacuum) = 2000.0 * thermal_power_received / maxISP / g0

now lets make some prediction based on the numbers you supplied for a Sethan (1.25):

ISP = 22.371670613 * Sqrt(3000) = 1225 s

Max Thrust = 2 *1000 * 187.5 MW / 1225 s / 9.82 = 31.17 kN

a bit disapointing,

fortunatly I have introduced a WarpPluginSetting called GlobalThermalNozzlePowerMaxTrustMult (default value 1)

if you want to achieve 105.728 kN, set the GlobalThermalNozzlePowerMaxTrustMult to 105.728 / 31.17 = 3,392

there is however is a problem that this will effect all existing ThermalNoozles in the game

fortunatly I have also introduced a module setting powerTrustMultiplier in FNNozzleController (default value 1)

this setting allows only new vessels (with newly added thermal nozzle part) to recieve the thrust bonus.

notice this part setting combined with ExitArea setting allow to create noozles optimised for several athmospheric conditions. Now If only a moddeler would be so kind to create some additional noozles, we could also offer a lot more choice!!

Except for new models, Modifying KSPI thrust never was so easy, now was it? :D

Try these same calculations using known Thermal Power, Heat Exchanger Temperature, and ISP values taken from a screenshot of a NTR in-flight... See if the predicted Thrust (for that reactor, using this formula as you understand it to work) matches the observed Thrust. I suspect it won't, because we don't know the value of "ispratio" yet, and it figures into the equation somewhere...

EDIT: Also, when everything is working correctly for the 1.25 meter "Sethlans" reactor, it should produce 225.25 kN Vacuum Thrust at 1225 seconds Vacuum ISP. That is because any additional ISP beyond 1000 seconds is due *PURELY* to the exhaust nozzle (which increases ISP by increasing Thrust for a given Mass Flow Rate, *NOT* reducing fuel-consumption...) and thus does not come at the expense of Vacuum Thrust, but rather to its benefit...

SethlansTarget Performance:

Vac Thrust 225.25 kN

Vac ISP 1225 seconds

Note that the high Vacuum ISP should come at a rather significant price in atmospheric ISP... The original Exit Area approximations for the Thermal Rocket Nozzles seem appropriate- although I still have no idea where to code in the formula I've been posting here (Atmospheric Thrust = Vacuum Thrust - Exit Area Factor * Background Pressure)

Regards,

Northstar

Edited by Northstar1989

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I already exactly know what everything is:

ispratio = currentIsp / maxISP (it's only relevant in the atmosphere, in vacuuum its 1)

heat_exchanger_thrust_divisor = match between reactor and nozzle (can be ignored when matched it becomes 1)

myAttachedEngine.currentThrottle = current engine trottle = vessel trottle (is 1 at maxumum trottle and can be ignored)

thrust_limit = is trottle configuration (normally set at 100% = 1 and can be ignored)

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Try these same calculations using known Thermal Power, Heat Exchanger Temperature, and ISP values taken from a screenshot of a NTR in-flight... See if the predicted Thrust (for that reactor, using this formula as you understand it to work) matches the observed Thrust. I suspect it won't, because we don't know the value of "ispratio" yet, and it figures into the equation somewhere...

Alright let's use the Sethan 2.5m 85MW 1173 Temp

Max ISP = 22.371670613 * Sqrt(1173) = 766,2 s

Max Thrust = 2 *1000 * 85 MW / 766,2 s / 9.82 = 22.59 which is the same as the value found on

https://github.com/FractalUK/KSPInterstellar/wiki/Thermal-Rocket-Nozzle-and-Thermal-Turbojet

Edited by FreeThinker

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So KSPI Vacuum is calculated by

ISP (Vacuum) = 2000.0 * thermal_power_received / maxISP / g0

now lets make some prediction based on the numbers you supplied for a Sethan (1.25):

ISP = 22.371670613 * Sqrt(3000) = 1225 s

Max Thrust = 2 *1000 * 187.5 MW / 1225 s / 9.82 = 31.17 kN

a bit disapointing,

fortunatly I have introduced a WarpPluginSetting called GlobalThermalNozzlePowerMaxTrustMult (default value 1)

if you want to achieve 105.728 kN, set the GlobalThermalNozzlePowerMaxTrustMult to 105.728 / 31.17 = 3,392

there is however is a problem that this will effect all existing ThermalNoozles in the game

fortunatly I have also introduced a module setting powerTrustMultiplier in FNNozzleController (default value 1)

this setting allows only new vessels (with newly added thermal nozzle part) to recieve the thrust bonus.

notice this part setting combined with ExitArea setting allow to create noozles optimised for several athmospheric conditions. Now If only a moddeler would be so kind to create some additional noozles, we could also offer a lot more choice!!

Except for new models, Modifying KSPI thrust never was so easy, now was it? :D

Try these same calculations using known Thermal Power, Heat Exchanger Temperature, and ISP values taken from a screenshot of a NTR in-flight... See if the predicted Thrust (for that reactor, using this formula as you understand it to work) matches the observed Thrust. I suspect it won't, because we don't know the value of "ispratio" yet, and it figures into the equation somewhere...

80honQO.jpg552VEZx.jpg

Pretty close

Edit, I made a little input error, corrected it and it shows the expected 105.7 kN (see next post)

Edot2: I also needed to increse all power output of the upgraded vrsion, to at least match the non upgraded reactor. I need updated power + temp for Dusty Plasma and Gas Core Reactor

Edited by FreeThinker

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I uploaded KSPI Extended 0.6

OpH8owD.jpgcqBxs8U.jpg

You can now download the new version of KSPI Extended 0.6 from KerbalStuff

Features

  • Significantly Increased Thermal Noozle trust
  • Adjusted Power output & Temperature Kiwi, Aegletes, Sethlans and Akula Reacors to realworld Timberwind reactors data
  • Made ISP/Trust performance of Plasma Thruster in atmosphere depend on exitArea 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 support for Community Tech Tree (CTT KSPI Config made by Olympic1)
  • 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 Computer Core would only give 1/4 of the research it should when unfocused
  • 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 KSPI Extended into Your GameData folder.

Changelog Version 0.6

  • Increased Thermal Noozle power by 339.2%
  • Adjusted Power output & Temperature Kiwi, Aegletes, Sethlans and Akula Reacors to realworld Timberwind reactors data

Edited by FreeThinker

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I uploaded KSPI Extended 0.6

http://i.imgur.com/OpH8owD.jpghttp://i.imgur.com/cqBxs8U.jpg

You can now download the new version of KSPI Extended 0.6 from KerbalStuff

Features

  • Significantly Increased Thermal Noozle trust
  • Adjusted Power output & Temperature Kiwi, Aegletes, Sethlans and Akula Reacors to realworld Timberwind reactors data
  • Made ISP/Trust performance of Plasma Thruster in atmosphere depend on exitArea 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 support for Community Tech Tree (CTT KSPI Config made by Olympic1)
  • 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 Computer Core would only give 1/4 of the research it should when unfocused
  • 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 KSPI Extended into Your GameData folder.

Changelog Version 0.6

  • Increased Thermal Noozle power by 339.2%
  • Adjusted Power output & Temperature Kiwi, Aegletes, Sethlans and Akula Reacors to realworld Timberwind reactors data

Did this change affect thermal turbojet thrust in atmospheric mode? My thermal turbojets are really weak now :(

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Did this change affect thermal turbojet thrust in atmospheric mode? My thermal turbojets are really weak now :(

Exising vessels should not be affected, only new vessels with the updated reactors, they would be more powerful..

Edited by FreeThinker

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Exising vessels should not be affected, only new vessels, they would be more powerful..

significantly weaker. using 1.25 meter parts: sabre intakes and cooler, omega fusion reactor, 2 small radial radiators, electric generator, and thermal turbojet in creative mode.

before I installed the mod tweaks.

unoWU9C.jpg

after the mod tweaks.

4M8TZtK.jpg

can anyone else confirm?

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significantly weaker. using 1.25 meter parts: sabre intakes and cooler, omega fusion reactor, 2 small radial radiators, electric generator, and thermal turbojet in creative mode.

before I installed the mod tweaks.

http://i.imgur.com/unoWU9C.jpg

after the mod tweaks.

http://i.imgur.com/4M8TZtK.jpg

can anyone else confirm?

We didn't touch the Fusion Reactors, so Thrust shouldn't be affected by the update.

Now if you saw decreased Thrust with the FISSION reactors, it might have been that we increased the Reactor Temperature of the fission reactors to more realistic values. However we also up-rated the Thermal Power to realistic values, so I would *EXPECT* more ISP *AND* Thrust using the Fission reactors...

Regards,

Northstar

- - - Updated - - -

I already exactly know what everything is:

ispratio = currentIsp / maxISP (it's only relevant in the atmosphere, in vacuuum its 1)

heat_exchanger_thrust_divisor = match between reactor and nozzle (can be ignored when matched it becomes 1)

myAttachedEngine.currentThrottle = current engine trottle = vessel trottle (is 1 at maxumum trottle and can be ignored)

thrust_limit = is trottle configuration (normally set at 100% = 1 and can be ignored)

Good stuff. Awesome!

I guess this only leaves me with one more concern about the fission reactors- do you think Fractal_UK will be willing to integrate the changes when he comes back, especially if they're in an outside-config rather than written into the main code itself?

Also, I'm still hoping we can get Carbon Dioxide working as a storable propellant in RealFuels. You took a look at that code I pasted before for that (using adding LqdWater wherever there's Kerosene as an example), right? In fact, I think you could just directly copy that code, just replacing "Kerosene" with "LqdMethane" which is the RealFuels version of Methane, and "LqdWater" with "CarbonDioxide" which is the CRP version of CO2- and do something similar with a Liquid CO2 resource as well).

Regards,

Northstar

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I uploaded KSPI Extended 0.6

-SNIP-

Changelog Version 0.6

  • Increased Thermal Noozle power by 339.2%
  • Adjusted Power output & Temperature Kiwi, Aegletes, Sethlans and Akula Reacors to realworld Timberwind reactors data

That's good (105.9 kN Vac Thrust is better than before), but still not up to the target performance:

Sethlans Target Performance:

Vac Thrust: 225.25 kN

Vac ISP: 1225 seconds

Sea-Level Thrust: 147.66 kN

Sea-Level ISP: 803.05 seconds

Remember, it should have 1/4th the Thermal Power of the Timberwind 75 (which produced 735.5 kN Vac Thrust) and 22.5% higher Thrust/MW due to the larger nozzle yielding 22.5% higher Vac ISP...

(735.5 kN / 4) * 1.225 = 225.25 kN

Also, what did you do with the "Exit Area" value? With ISP multiplier currently set to reflect the larger nozzle size, the Exit Area should be left at 0.7657 m^2 for the 1.25 meter Thermal Rocket Nozzle, leading to the lower Sea-Level Performance than the Timberwind...

In short, the nozzle on *OUR* NTR is designed more like an upper-stage nozzle than a launch-nozzle: which leads to a higher Vac ISP, but a lower Atmospheric ISP than the Timberwind designs... (which were designed as launch engines)

Regards,

Northstar

Edited by Northstar1989

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OK, so I performed some quick testing (launching a NTR with Infinite Fuel to get it above the atmosphere) in vacuum conditions confirmed it is at least getting the right ISP and ThermalPower, and it matches up with your results.

Now, we just need to fix the Thrust/MW...

The CORRECT Thrust/MW is 2.127 times higher than it is currently set.

REMEMBER, the additional Vacuum ISP beyond 1000 seconds (the Vacuum ISP of Timberwind) is *NOT* due to concentrating the ThermalPower in less exhaust mass, it is due to harvesting a larger % of the energy of the exhaust stream with a larger exhaust nozzle- and thus achieving higher Thrust for the same Mass Flow Rate and ThermalPower (indirectly increasing Vacuum ISP in the process) at the expense of increased atmospheric-compression...

So, we need to multiply the Thrust/MW by an additional 212.7% (712.5% increase vs. before the 0.60 Extension Config).

We also need to fix the calculation for Atmospheric ISP to be based on the formula I presented earlier (Atmospheric Thrust = Vacuum Thrust - Exit Area * Background Pressure). Right now the Thermal Rocket Nozzle is still only operating at an ISP of about 490 seconds at sea-level, instead of 803.5 seconds... This appears to be as it is still using the stock atmosphere curve (where sea-level ISP is set to 40% of vacuum ISP, regardless of throttling) originally provided by Fractal_UK...

This means eliminating the "ispratio" term in Fractal_UK's equation for Thrust, and instead subtracting (Exit Area * Background Pressure) from the rest of the equation, where Background Pressure is in kPa.

Regards,

Northstar

Edited by Northstar1989

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significantly weaker. using 1.25 meter parts: sabre intakes and cooler, omega fusion reactor, 2 small radial radiators, electric generator, and thermal turbojet in creative mode.

before I installed the mod tweaks.

http://i.imgur.com/unoWU9C.jpg

after the mod tweaks.

http://i.imgur.com/4M8TZtK.jpg

can anyone else confirm?

Could you please try with previous versions..I haven't changed anything in the dll, but I did in the past. I need to know exactly at what point the problem might have been introduced.

Edited by FreeThinker

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