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[1.1.2] Realism Overhaul v11.0.0 May 8

Felger

By Felger
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Nildran

Nildran

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I begin on RSS / RO with a RP0 career. I do not manage to make rockets with several stage because a problem of "vapor in feed lines". After some searches on the forum, I read that it was necessary to use "ullage" but I do not how understand to make. Can you help me ?

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63Hayden

63Hayden

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Posted
5 hours ago, Nildran said:

I begin on RSS / RO with a RP0 career. I do not manage to make rockets with several stage because a problem of "vapor in feed lines". After some searches on the forum, I read that it was necessary to use "ullage" but I do not how understand to make. Can you help me ?

Right. I had this problem too, when I first started out with realism overhaul. It's a feature introduced by Real Fuels, which is relied upon by RO itself. The 'vapor in feedlines' message that you get appears when the fuel in your storage tank is 'unstable', which is to say that it has collected at the opposite end of the tank, away from the engine. What you need to do is get the fuel and oxidizer into the feedlines using a small measure of thrust; just enough to move the liquids back. This can be achieved by using separation motors in the proceeding stages of your rocket. Once you're been in space for a while, the fuel/oxidizer will naturally move around in the storage tank, but you can just use small pulses of RCS thrust to alleviate this. The best way to identify the current state of the fuel/oxidizer in your stage is to right click on the engine utilizing said liquids; somewhere in that summary you'll find what I'm talking about.

Hope this information helps.

Regards,

Hayden

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Guest

Guest

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Posted
6 hours ago, Nildran said:

I begin on RSS / RO with a RP0 career. I do not manage to make rockets with several stage because a problem of "vapor in feed lines". After some searches on the forum, I read that it was necessary to use "ullage" but I do not how understand to make. Can you help me ?

basicly you need a way to "settle" the fuel. I suggest attaching (in 2x mode) the tiny separator motors to the stage that needs ullage (pointing downwards in same direction as rocket bell), set them to activate when you decouple with the next staging being the one that activates the rocket, attempt to activate the rocket 50% to 75% of the way through the separators burn. These separators are also handy for setting up "spin stabilization", if angled, on unguided rockets and/or stages

 

do you understand my explanation?

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mwg_test

mwg_test

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Hello everyone.  
A weel ago i tried to start RSS+RF+RO game. And it's really whole new gameplay. I am really exited for now, but i still have some troubles.
As i not simulating real-life missions so i decided to use nuclear and ion engines in game, but asmall problem is still here. 
The NAVSTAR engine is the only engine wich uses nuclear power, and it uses liquid hydrogen. But for simple 6km\s delta for 80t payload this tanks is EXTREMLY lagre. 
In 1st post here in description - there are 3 more 

Quote

====Nuclear (Liquid Fuel)====

In general: the less dense the fuel, the higher your specific impulse and the lower your thrust.

*Liquid Hydrogen is the benchmark. Highest performance, but least dense. Same drawbacks as hydrolox, above, except worse, because ALL the fuel is liquid hydrogen

*Liquid Methane has lower performance, but is much more dense and so, despite, the lower specific impulse, the lower tank mass often leads to higher total deltaV for your stage. Considerable increase in thrust.

*Liquid Ammonia has lower performance but also less of a thrust increase than Liquid Methane.

*LOx-Augmented NTR: This involves pumping LOx into the nozzle along with the expelled, superheated LH2, thus having them combust. Thus you get a hybrid between a chemical rocket and a NTR. Massive thrust increase (8x or so) with a drop in efficiency down to about 65-70% what the NTR gets in pure-LH2 mode.

I tried every RO-supported mods with nuclear engines, and never found working NTR(all were with "NO RO").
So can u help me make upper stage with NTR and methane or ammonia?
I can not reach Moon without tiny upper stage because of epic lags with chemical fuel, and with Ion engines - because of huge time IRL to make burn to moon(18h burn makes me sick).

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Phineas Freak

Phineas Freak

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These are theoretical options for a nuclear - thermal engine. The actual implementation is left upon the person than will create the actual RO configuration for the part.

Stock NTR supports LH2 mode only (although it should be extended to support LOX injection, like the LANTR). I am not aware of any engine that supports Ammonia or Methane (these should also be sub - configs of the stock NTR).

For ion engines, it is strongly recommended that you use the Solar Sail Navigator mod. Do not be alarmed by the name: the base functionality is to allow thrust while the vessel is on rails.

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mwg_test

mwg_test

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13 minutes ago, Phineas Freak said:

These are theoretical options for a nuclear - thermal engine. The actual implementation is left upon the person than will create the actual RO configuration for the part.

Stock NTR supports LH2 mode only (although it should be extended to support LOX injection, like the LANTR). I am not aware of any engine that supports Ammonia or Methane (these should also be sub - configs of the stock NTR).

For ion engines, it is strongly recommended that you use the Solar Sail Navigator mod. Do not be alarmed by the name: the base functionality is to allow thrust while the vessel is on rails.

thx for SSN mod, i'll try.
Is there any manual, how to create "copy" of current NTR with LOX+LH2\methane\ammonia support? or add to engine config ability to use them with lower Isp and higher thrust?

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Phineas Freak

Phineas Freak

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Manual, no but you can open the file "RO_Squad_Engines.cfg" (located under "RealismOverhaul/RO_SuggestedMods/Squad"), find the nuclearEngine and take a look at it's ModuleEngineConfigs module. Then create a new CONFIG{} with your preferred engine parameters. Just copy the existing configuration and add / remove the new fuels.

I will make a PR to the RO GitHub to include new NTR modes.

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Starwaster

Starwaster

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5 hours ago, Phineas Freak said:

Manual, no but you can open the file "RO_Squad_Engines.cfg" (located under "RealismOverhaul/RO_SuggestedMods/Squad"), find the nuclearEngine and take a look at it's ModuleEngineConfigs module. Then create a new CONFIG{} with your preferred engine parameters. Just copy the existing configuration and add / remove the new fuels.

I will make a PR to the RO GitHub to include new NTR modes.

I suggest looking at Raptor's stockalike engines for a starting point. The NTR / LANTR engines there are based on configurations resulting from some fairly exhaustive research and the configs should be reasonably accurate as to thrust / Isp. Originally they were based around the Pewee 2 engines progressing up to modern theoretical designs as tech level increased but I think that part fell by the wayside as the code changed.

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user_337

user_337

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So, I'm wondering if someone else has had the same issue or could try this out and see if it works on their system: I am trying to Re-enter using the Apollo CSM from FASA with RO and RSS on a skip out trajectory back from the moon. It appears however that the CSM has some serious heating issues during re-entry. I have some screen shots to prove it available upon request. I have attempted this successfully with other command pods like the MK2. Initial issues begin at ~100km elevation; at this point my stowed parachutes explode followed by all other parts attached to the CSM. The CSM eventually explodes at 75km. Re-entry velocity is 10.5km/s at 130km with a periapsis at 75km. All supporting mods are completely up to date (done daily) and I am on version 1028. 

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Phineas Freak

Phineas Freak

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@Starwasterthank you for your suggestion! I took a look at the configurations and after making a quick comparison with some data that i found i can also conclude that the values used are accurate.

Question: what should we do with the stock NTR thrust level? The thrust is accurate but the base configuration will be OP as hell (330 kN thrust, 925 s VACISP) in comparison with the other modes provided by RFS.

Edit: and the weird thing is that some papers mention high thrust values but others low:

http://alternatewars.com/BBOW/Space_Engines/AIAA-2004-3863_TRITON.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960002346.pdf

Edited by Phineas Freak
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KingKappa

KingKappa

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Hey,

I wanted to start playing with popular mods installed, so that they are there and I can possibly learn on the fly.

 

I tried to run Kerbal with RO installed, but module manager would freeze at 7661 patches with tinytim/tinytim/tinytim and if I removed that folder it would instead freeze at a random part file. Does anyone know a workaround? Thanks!

(In the meantime im just not using it, but would love to have the addition!)

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Starwaster

Starwaster

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Posted (edited)
4 hours ago, Phineas Freak said:

@Starwasterthank you for your suggestion! I took a look at the configurations and after making a quick comparison with some data that i found i can also conclude that the values used are accurate.

Question: what should we do with the stock NTR thrust level? The thrust is accurate but the base configuration will be OP as hell (330 kN thrust, 925 s VACISP) in comparison with the other modes provided by RFS.

Edit: and the weird thing is that some papers mention high thrust values but others low:

http://alternatewars.com/BBOW/Space_Engines/AIAA-2004-3863_TRITON.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960002346.pdf

Sigh, was 3/4 of the way through a reply when I hit backspace. And these new forums don't seem to save draft content? (It's perfectly content to throw old quoted text and replies into my composed message)

Those thrust/Isp numbers sound right for high end engines depending on how hot the core gets and how much propellant you throw into it. Not really that OP. Don't forget that engine mass for those engines can be high and some of the numbers see see quoted might be sans shielding. (Unmanned missions might get by with less shielding but not manned)

Denser propellants will have higher thrust and lower Isp. Delta-V will be marginally higher for the denser propellants but still less per kg than H2.

Originally as far as specific thrust and Isp, I had set it up such that TL 5 would yield the 111 kN engine (based on the Pewee 2) which is usually what you see in the Mars DRA documents. LANTR and Triton are also usually based around those designs. Higher thrust engines would be NERVA or NX (aka Nuclear Furnace). So I'd setup things so that TL 5 is the baseline with TL 3/4 being either prototype and experimentals (i.e. Project Rover) and higher TL than 5 would be more advanced or just more powerful. I wouldn't worry that much about it being OP if you give the engines appropriate masses and pricing.

Edit: RE: LANTR. Be careful that in both modes that the H2 mass flow is the same! It's easy to configure it such that flow changes and it should not. The propellant flow is the same except that LOX is injected into the nozzle exhaust where it spontaneously combusts (similar to an afterburner). (because of this, any implied 'tradeoff' is incorrect. There are only gains from doing this; the altered Isp is only for computing the new thrust level)

Edited by Starwaster
The LANTR Edit
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dasbin

dasbin

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I'm having trouble with the Multi-Hundred Watt RTG since updating RO to v 10.7.2 on CKAN.

It doesn't seem to generate any power any more. I notice now it contains a "Plutonium" resource that it didn't on previous versions, and its status always reads "DepletedFuel Full".

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NathanKell

NathanKell

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47 minutes ago, dasbin said:

I'm having trouble with the Multi-Hundred Watt RTG since updating RO to v 10.7.2 on CKAN.

It doesn't seem to generate any power any more. I notice now it contains a "Plutonium" resource that it didn't on previous versions, and its status always reads "DepletedFuel Full".

@Phineas Freak any idea what might be going wrong here?

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StallionHurdler

StallionHurdler

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23 hours ago, StallionHurdler said:

Can anyone tell me why my dish and antenna range has not extended while using realism overhaul and real solar system? The pioneer dish says it should be able to connect to Juipter, yet I can not even connect to Venus. 

Plz if anybody can help it would be appreciated. It seems realism overhaul is not adjusting the communication ranges of remote tech. 

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Blipser1

Blipser1

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3 hours ago, NathanKell said:

@Phineas Freak any idea what might be going wrong here?

I've also had this problem, what seems to be happening is the RTG is trying to generate depleted fuel but there aren't any possible containers for it in RO so instead the part just complains it cant create it's outputs and won't start. I've fixed it by editing the RO_Squad_Electrical.cfg so that the part no longer generates depleted fuel, but a better long term fix would be to add the ability to hold depleted fuel in modular tanks.

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mwg_test

mwg_test

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3 hours ago, Blipser1 said:

I've also had this problem, what seems to be happening is the RTG is trying to generate depleted fuel but there aren't any possible containers for it in RO so instead the part just complains it cant create it's outputs and won't start. I've fixed it by editing the RO_Squad_Electrical.cfg so that the part no longer generates depleted fuel, but a better long term fix would be to add the ability to hold depleted fuel in modular tanks.

hmm, so - the RTG is the thing, wich generates electricity from heating. Heating source is plutonium and it have half time about 87 years. After 87 years you will have half of your starting 238Pu and half - depleted 234U. Fuel can not be transferred - it's just transmorfing one into another. So if you have 5 units of 238Pu - after 87 years you will have 2.5 units of 238Pu and 2.5 units of 234U. after 87 more years - 1.25 238Pu and 3.75 234U. Total size does not change. So if you want have electricity longer - only way is to make MORE starting RTGs, cause of you can not just keep fuel - it still will be decaying. Or you can try to synthesize it from 238U by bombardig it with 2H

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