Realism Overhaul Discussion Thread

[legoclone09]

Just here to say I landed a probe on the Moon, here is the lifter: [IMG]http://i.imgur.com/uCMFpR1.jpg[/IMG]
Here is the probe, landed: [IMG]http://i.imgur.com/YGQPCcc.jpg[/IMG]

[MaxL_1023]

What engine did you use that gave you 3.6 kN of thrust? Do the 1 kNs get that high at tech level 7?

[legoclone09]

I used the Aerozine50/NTO 2kN thrusters at tech level 7. The normal 1 kN thruster with that configuration has 1.8 kN.

[ColKlonk]

I seem to have lost my smoke at launch.. when installing RO which I'm not whether it connected to my cloud loss in enhanced environment
This happened after installing just the required RO mods.. has this happened to anyone else ?

Mods..
[img]http://i.imgur.com/efeO1qP.jpg[/img]


Engines on before releasing clamps..
[img]http://i.imgur.com/BQyVTcb.jpg[/img]

Going up... no smoke... I think that's the right plume for LHO
[img]http://i.imgur.com/cCdpnV1.jpg[/img]

Further up the road .. plume looking good.. but no trail..
[img]http://i.imgur.com/XQbqdaf.jpg[/img]

Ullage SRBs
[img]http://i.imgur.com/etkZG0g.jpg[/img]

Beaming down the 'home stretch'
[img]http://i.imgur.com/8QiXzG8.jpg[/img]

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Forgot to add.. the engines are BobCats RD-120s (Soviet Engines)
I also installed Stock plumes with the RealPlumes mod.
:) Edited November 21, 2015 by ColKlonk

[Red Iron Crown]

ColKlonk: Some propellant combinations in RO do not produce smoke, just a plume, as in real life. An example would be the Space Shuttle, the SRBs produce tremendous amounts of smoke but the main engines don't produce any ([URL="http://www.nasa.gov/sites/default/files/images/110876main_image_feature_287_ajhfull.jpg"]sample pic[/URL]).

[ColKlonk]

I was under the Impression that firing up Hydrogen and Oxygen produced a water vapour cloud.. that one sees at the shuttle launches

I'll have a quick check at the launch videos again, for the correct sequence of smoke
:)

Edt: At 48/9 secs, just before SRB ignition.. I suppose it's water from the tower...
[URL]https://www.youtube.com/watch?v=4FROxZ5i67k[/URL] Edited November 21, 2015 by ColKlonk

[MaxL_1023]

Is there a way to negate all liquid hydrogen boiloff? I tried using active radiators and a cryogenic tank but I still lost everything within a couple months. I wanted to use a radioisotope rocket for probes and need liquid hydrogen for fuel.

[ColKlonk]

[quote name='MaxL_1023']Is there a way to negate all liquid hydrogen boiloff? I tried using active radiators and a cryogenic tank but I still lost everything within a couple months. I wanted to use a radioisotope rocket for probes and need liquid hydrogen for fuel.[/QUOTE]
Not that I know of, at the mo... maybe you can use one of those TAC sabatier carbon converters that produces hydrogen as a waste product.

I don't think there is an thermally controlled 'thermoflasks' to store LQH.. would be an idea though.
:)

[Nansuchao]

Or you can prevent boil off using reactors from Interstellar Extended. Some of them can produce a good amount of energy for a long time and helps to maintain propellant at cryogenic temperatures.

[Luxius]

I've searched a great deal for the answer to this question, but it seems it hasn't been raised? If so, please excuse me bringing up the question again:

There's been numerous discussions regarding the [URL="https://en.wikipedia.org/wiki/Ullage_motor"]ullage motor[/URL], what it does and why it does it, but I can't seem to find any interest in the ullage space in fuel tanks. But I was wondering why a new procedural tank defaulted @ 84% space used for fuels the first time I built a rocket in Realism Overhaul (with RP-0). I've simply adjusted this to 100% at all times, not knowing if it had any relevant consequences. Does RO take tank ullage into consideration? If so, are the numbers adjusted accordingly for each type of fuel mix or should I simply expect a flat 16% usage for gasses and such (which seems a bit much compared to the numbers I've read elsewhere on the subject)? Also, if ullage in tanks are simulated in RO, how does pressurized tanks and cryo affect this?

Please bear in mind, I am not a professional rocket scientist, I am merely trying to understand these concepts as an amateur geek - so don't hold back if I need be corrected in my observations! Thank you!

/Luxius

last edit: still don't get what this post is about? Well, as I understand it, the fuel tank NEEDS to have room at the top, so you as an engineer can control where the gaseous fuels will be gathering - cause there will always be some percentage of your fuel going from liquid to gas and back to liquid (due to entropy, quantum laws and other physics I won't exaggerate my comprehension of). Feel free to correct this observation!

Relevant link: [URL="http://space.stackexchange.com/questions/4434/how-much-potential-volume-in-a-rockets-tank-is-actually-used-for-fuel"]http://space.stackexchange.com/questions/4434/how-much-potential-volume-in-a-rockets-tank-is-actually-used-for-fuel[/URL] Edited November 22, 2015 by Luxius
clarification, syntax, grammar and typo corrections

[Svm420]

[quote name='Luxius']I've searched a great deal for the answer to this question, but it seems it hasn't been raised? If so, please excuse me bringing up the question again:

There's been numerous discussions regarding the [URL="https://en.wikipedia.org/wiki/Ullage_motor"]ullage motor[/URL], what it does and why it does it, but I can't seem to find any interest in the ullage space in fuel tanks. But I was wondering why a new procedural tank defaulted @ 84% space used for fuels the first time I built a rocket in Realism Overhaul (with RP-0). I've simply adjusted this to 100% at all times, not knowing if it had any relevant consequences. Does RO take tank ullage into consideration? If so, are the numbers adjusted accordingly for each type of fuel mix or should I simply expect a flat 16% usage for gasses and such (which seems a bit much compared to the numbers I've read elsewhere on the subject)? Also, if ullage in tanks are simulated in RO, how does pressurized tanks and cryo affect this?

Please bear in mind, I am not a professional rocket scientist, I am merely trying to understand these concepts as an amateur geek - so don't hold back if I need be corrected in my observations! Thank you!

/Luxius

last edit: still don't get what this post is about? Well, as I understand it, the fuel tank NEEDS to have room at the top, so you as an engineer can control where the gaseous fuels will be gathering - cause there will always be some percentage of your fuel going from liquid to gas and back to liquid (due to entropy, quantum laws and other physics I won't exaggerate my knowledge about). Feel free to correct this observation!

Relevant link: [URL]http://space.stackexchange.com/questions/4434/how-much-potential-volume-in-a-rockets-tank-is-actually-used-for-fuel[/URL][/QUOTE]
The percent you are talking about is not free space in the tank it is the structre of the tank. The walls and other components that make up the tank itself. You putting it to 100% mean you have no tank just fuel. Not real at all. No tank type effect ullage AFAIK just the types of fuel that can be stored and whether there is insulation on the tanks. I don't really understand what you are talking about ullage motors. So please clarify if that was a question.

[Luxius]

[quote name='Svm420']The percent you are talking about is not free space in the tank it is the structre of the tank. The walls and other components that make up the tank itself. You putting it to 100% mean you have no tank just fuel. Not real at all.[/QUOTE]
You're saying I'm unwittingly breaking realism by putting 0% structure into my tank? That this is merely something I shouldn't touch if I want realism? So ... why can I adjust it in RO? Wouldn't it be possible to hard-code this number? No criticism of RO, just trying to make sure I understand your statement correctly.


[quote name='Svm420']No tank type effect ullage AFAIK just the types of fuel that can be stored and whether there is insulation on the tanks.[/QUOTE]
Please see the "relevant link" and the answer below on that page.

[quote name='Svm420']I don't really understand what you are talking about ullage motors. So please clarify if that was a question.[/QUOTE]
I am specifically trying not to discuss ullage motors, I'm sure I understand the concept of those. There was no question regarding the motors that generate G-forces to force the liquids to the nozzle for the engine ... blahblahblah. All questions were regarding the [URL="https://en.wikipedia.org/wiki/Ullage_%28wine%29"]ullage[/URL] in the tank needed to control/guide the gaseous vapours inside the tank as far as possible away from the engine. Again, see the link at the bottom in above post. If you merely filled the tank to the limit, all those gasses in the fuel would be, I assume, diluted into the fuel mix, and you don't want ANY vapours in the engine AT ALL. Pressure is nice, but if you OVER-pressure the fuel inside the tank, you essentially capture all the bubbles like it's done in Coca-Cola.

/Luxius

Edit: To put it in another way, if you want to push the liquids to the "bottom", this actually means you reactively want to push the gasses to the "top". If the tank is filled to the top with no ullage space, there is nowhere the gasses can be pushed to. The "ullage space" in the tank in [URL="http://i.stack.imgur.com/khS7e.jpg"]this picture[/URL] would be the "gaseous hydrogen" part. Edited November 22, 2015 by Luxius

[Svm420]

[quote name='Luxius']You're saying I'm unwittingly breaking realism by putting 0% structure into my tank? That this is merely something I shouldn't touch if I want realism? So ... why can I adjust it in RO? Wouldn't it be possible to hard-code this number? No criticism of RO, just trying to make sure I understand your statement correctly.



Please see the "relevant link" and the answer below on that page.


I am specifically trying not to discuss ullage motors, I'm sure I understand the concept of those. There was no question regarding the motors that generate G-forces to force the liquids to the nozzle for the engine ... blahblahblah. All questions were regarding the [URL="https://en.wikipedia.org/wiki/Ullage_%28wine%29"]ullage[/URL] in the tank needed to control/guide the gaseous vapours inside the tank as far as possible away from the engine. Again, see the link at the bottom in above post. If you merely filled the tank to the limit, all those gasses in the fuel would be, I assume, diluted into the fuel mix, and you don't want ANY vapours in the engine AT ALL. Pressure is nice, but if you OVER-pressure the fuel inside the tank, you essentially capture all the bubbles like it's done in Coca-Cola.

/Luxius

Edit: To put it in another way, if you want to push the liquids to the "bottom", this actually means you reactively want to push the gasses to the "top". If the tank is filled to the top with no ullage space, there is nowhere the gasses can be pushed to. The "ullage space" in the tank in [URL="http://i.stack.imgur.com/khS7e.jpg"]this picture[/URL] would be the "gaseous hydrogen" part.[/QUOTE]
It won't break realism, it just isn't realistic. It is allowed so that you could in theory simulate tanks with different dry masses as I am sure not every tank in the world throughout history had the same dry mass though they are probably very close.. Sure you could argue that they could make a limit to prevent unrealistic dry masses, but it's a single player game no one stops you from cheating in any number of ways. Pressure has no effect on ullage in microgravity. I really don't get what you're getting at the mod handles free space in the tank due to fuel being used, so you need not worry if you have enough room for the gases. That is an abstraction done for the sake of simplicity and gameplay. I think you are overthinking it.

[Luxius]

[quote name='Svm420']I think you are overthinking it.[/QUOTE]

If we can at least agree, that ullage in tanks are a real subject in real life, should your above answer then be regarded as, "no, it is not simulated, because it is such a small factor"? Sorry for thinking too much!

I wasn't referring to the option of cheating, I was asking if it would be possible to make limits - for those interested in restrictions set by realism, but who don't (yet) possess the needed knowledge of how numbers should be interpreted in the game/mod.

/Luxius

Blaze it, bro.

[Red Iron Crown]

[quote name='Luxius']I am specifically trying not to discuss ullage motors, I'm sure I understand the concept of those. There was no question regarding the motors that generate G-forces to force the liquids to the nozzle for the engine ... blahblahblah. All questions were regarding the [URL="https://en.wikipedia.org/wiki/Ullage_%28wine%29"]ullage[/URL] in the tank needed to control/guide the gaseous vapours inside the tank as far as possible away from the engine. Again, see the link at the bottom in above post. If you merely filled the tank to the limit, all those gasses in the fuel would be, I assume, diluted into the fuel mix, and you don't want ANY vapours in the engine AT ALL. Pressure is nice, but if you OVER-pressure the fuel inside the tank, you essentially capture all the bubbles like it's done in Coca-Cola.

/Luxius

Edit: To put it in another way, if you want to push the liquids to the "bottom", this actually means you reactively want to push the gasses to the "top". If the tank is filled to the top with no ullage space, there is nowhere the gasses can be pushed to. The "ullage space" in the tank in [URL="http://i.stack.imgur.com/khS7e.jpg"]this picture[/URL] would be the "gaseous hydrogen" part.[/QUOTE]
If you mean the gases that are released into a tank to fill the empty space as propellants are burned (usually helium or some other inert gas) then no, that isn't specifically simulated, it is instead abstracted as part of the dry mass/volume of the tank.

Not sure why you're linking a wine-making wiki page, did you mean to link another?

[Luxius]

[quote name='Red Iron Crown']If you mean the gases that are released into a tank to fill the empty space as propellants are burned (usually helium or some other inert gas) then no, that isn't specifically simulated, it is instead abstracted as part of the dry mass/volume of the tank.[/QUOTE]
Cool, thanks.

[quote name='Red Iron Crown']Not sure why you're linking a wine-making wiki page, did you mean to link another?[/QUOTE]
To redirect the question at the term ullage and not the motors intended to deal with ullage in micro-gravity. Ullage motors are intended for micro-gravity. Ullage in tanks is to be considered pre-launch (edit: at least for the first stage) and the first seconds after launch. When enough fuel is burned from launch it will no longer become an issue, since there will subsequently be plenty of room for the gasses to gather in.

Thank you for all your answers, both of you.

/Luxius

Addendum: has any of you actually read the scientific paper linked in the answer to the question in my former "relevant link" before trying to answer my question? Even taken a glimpse at it?

[COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR]

[quote name='Luxius']Addendum: has any of you actually read the scientific paper linked in the answer to the question in my former "relevant link" before trying to answer my question? Even taken a glimpse at it?[/QUOTE]

Or maybe I'm completely mistaken in my previous observations and it's all related to structural integrity and the expanding gasses ...? Edited November 23, 2015 by Luxius

[Svm420]

[quote name='Luxius']Cool, thanks.


To redirect the question at the term ullage and not the motors intended to deal with ullage in micro-gravity. Ullage motors are intended for micro-gravity. Ullage in tanks is to be considered pre-launch (edit: at least for the first stage) and the first seconds after launch. When enough fuel is burned from launch it will no longer become an issue, since there will subsequently be plenty of room for the gasses to gather in.

Thank you for all your answers, both of you.

/Luxius

Addendum: has any of you actually read the scientific paper linked in the answer to the question in my former "relevant link" before trying to answer my question? Even taken a glimpse at it?

[COLOR=silver][SIZE=1]- - - Updated - - -[/SIZE][/COLOR]



Or maybe I'm completely mistaken in my previous observations and it's all related to structural integrity and the expanding gasses ...?[/QUOTE]
Just read it Helium is pumped in up to a rated psi to ensure proper fuel flow into the turbopump. Release valves open to prevent over pressurization. That's drastically simplified, but that's the jist. The only thing this really applies to in RO is service modules are highly pressurized like that for RCS to work.

[maxdreamland]

Hi,

I have a performance issue with RSS and RO. And the fact that I don't read about this significant drop of performance anywhere else lets me assume that this is not a general problem with the addon but something locally on my system or install. But to be sure, and before i invest a lot of time investigating the problem I wanted to quickly hear what you guys have to say about it.

I started using RSS and RO a couple of weeks ago (installed via CKAN) and initially I enjoyed it very much. That was until I hit crafts with a part count around 75-80 parts. then the framerate dropped dramatically and an in-game second now takes several realtime seconds to simulate. An 8-9 minute flight to orbit easily takes 25-30 realtime minutes now. And as you can guess, it's not fun anymore :-)

Partly because of this performance issue I upgraded my system last weekend to a brand new Core i7 6700K overclocked to run at 4.7Ghz with a Geforce GTX 680 (i kept the graphics card from the previous PC for now). this helped with the problem but the difference between "stock KSP" and "KSP with RSS/RO" is still night and day. Without RSS/RO I can easily launch crafts with 75-80 parts with no problem (even larger craft with 100+ parts are no problem). It's 60 fps all the way to orbit.

but with RSS/RO installed the 75-80 parts craft is down to around 30fps and the time indicator on the top left corner is going yellow.

so now i'm wondering if this performance drop is just something that comes with the increased complexity of RO and needs to be accepted (and has been accepted and is therefore not discussed on the forums, therefore i couldn't find any information about it?)

or is there something fishy with my install? Is it unusual to experience this significant performance drop off and is it therefore worth my time investigating this?

thanks in advance!

best regards
Max

[ColKlonk]

Can one land on the MKS 'carrier' deck with RSS/RO... (Still building an automated ISS system - so not sure about this idea)
Just thinking of this type of 'space deck' where you can land/refuel, and have a cup of tea while in moon transit. :D

[img]http://i.imgur.com/1BD7m3S.jpg[/img]

[img]http://i.imgur.com/onINlqV.jpg[/img]

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MaxDreamLand... Nah.. I don't think its RSS/RO.. as I have a GTX 560 with 1MB with KSP mods = 11336 patches + Ships with 130-150 parts and have no problems.
you might have some incompatible mods that are spamming the log file... this is usually the cause of Frame Rate [I]failure[/I].

[MaxL_1023]

With respect to frame rate, I seem to have trouble based on the rocket mass, not the number of parts. Usually the majority of specific parts are on or near my payload state (I use procedural for fuel tanks). When my rocket gets into the 1000+ ton range (one shot 5 tons to Neptune FTW) the game slows down, as if it can't process the physics fast enough. By the time I decouple my first stage the game is speeding up, as I have burned away most of my mass. Once I get to second stage separation the game is basically at full speed.

In RSS/RO your launch vehicles are a lot larger than in stock - if the game is modeling rocket parts using some type of mass or size based mesh then larger vehicles will lead to problems.

[maxdreamland]

Thanks for the feedback. I'll have a look at the log, thats actually a good idea that i could have had myself :-)

[PLAD]

The other day I was building a large craft, the biggest ever RO first stage for me. After testing it with seven F-1's  I added 2 SRB's to it and the framerate plummeted, then picked up noticeably as the SRB's burned out. For that one I changed a Smokescreen parameter and I never saw the problem again. I used Toolbar to change the Smokescreen config item 'maximumActiveParticles' from the default ( I think 5000?) to 100. I admit I didn't change it back to 5000 afterward to prove it was the problem, but it's still working great with 9 F-1's and 4 SRB's.

 

[AviatorTrainman]

Sorry, I don't know if this has been asked yet, but how do I change the launch site if all of the KSC is underground at that site?

[MaxL_1023]

Assuming you have the KSC relocation mod, you can change your launch site using the tracking station. On the map of Earth/Kerbin you should see a bunch of small rocket icons - click one to move your launch site. Your KSC relocates, keeping all upgrades. 

[NathanKell]

Uninstall KSC Switcher. Launch the game and save. Load the save and save again (just to be sure) and finally quit and reinstall KSC Switcher. That should get you away from the broken site.