[1.8+] Real Fuels

[RedAV8R]

Sorry what was that Soyuz Apollo incident mentioned above here? Never heard of major problems with that mission and never heard of any problems regarding fuel. Can anybody please tell me what the matter was just for me to google it maybe?

What is wrong with those screenshots where an engine has options for the fuel but nothing regarding oxidizer?

Who knows what was the specific impulse of the attitude thrusters on the Apollo command module? As far as I can believe the web including Wikipedia they did not carry that much fuel but even that was sufficient for several minutes of intense control inputs. Also what makes me think that those engines were bipropellant? Regarding the game I am still looking for a way to simulate this on the command pods. Is it possible to add the configs for working thrusters just directly to the command pod not a separate part that would fit on via the module manager for example? Quite impossible to get the same effect by fitting bulky thrusters on the outer surface of the capsule.

N2O4 valve was left open (either negligent or failure), and fumes entered cabin via cabin air intake while on descent. Knocked 1 crew member unconscious for a bit until emergency oxygen mask was put on by another member. All 3 crew were in the hospital for 2 weeks with respiratory issues.

Test, his config was screwed up.

Isp for the Apollo CSM was 274s, yes it is a hypergolic bipropellant mixture of MMH/N2O4. To do what you want is possible, by adding MODEL{} calls and using whatever thruster(s) you want with position and orientation, then a simple ModuleRCSFX with whatever propellant you want.

[ialdabaoth]

Feature request for RealFuels:

it would be AWESOME if, when I right click on an engine or RCS block with a ModuleEngineConfigs (or derivative), if it would give some kind of display of how much fuel it has available. That way, if it says "NO FUEL FLOW", I know that I've put it in the wrong spot BEFORE I launch.

[Agathorn]

Feature request for RealFuels:

it would be AWESOME if, when I right click on an engine or RCS block with a ModuleEngineConfigs (or derivative), if it would give some kind of display of how much fuel it has available. That way, if it says "NO FUEL FLOW", I know that I've put it in the wrong spot BEFORE I launch.

A way to ensure that an engine has fuel flow in general would be awesome. Even more amazing would be something like CLS where you could select an engine and actually visualize all the tanks which can feed it.

[Starwaster]

N2O4 valve was left open (either negligent or failure), and fumes entered cabin via cabin air intake while on descent. Knocked 1 crew member unconscious for a bit until emergency oxygen mask was put on by another member. All 3 crew were in the hospital for 2 weeks with respiratory issues.

Test, his config was screwed up.

Isp for the Apollo CSM was 274s, yes it is a hypergolic bipropellant mixture of MMH/N2O4. To do what you want is possible, by adding MODEL{} calls and using whatever thruster(s) you want with position and orientation, then a simple ModuleRCSFX with whatever propellant you want.

If desired, you can use MODEL{} nodes that contain only the necessary thruster transforms using empty GameObjects created in Unity.

Edit: ModuleEngines uses Z axis; RCS uses Y axis

[RedAV8R]

If desired, you can use MODEL{} nodes that contain only the necessary thruster transforms using empty GameObjects created in Unity.

Edit: ModuleEngines uses Z axis; RCS uses Y axis

And with ModuleRCSFX you can use either.

[Rayder]

I've been doing a few calculations and my result is that for a given engine, with all other things equal, using Hydrolox gives only 40% the thrust of Kerolox.

I'm not sure I'm calculating it properly, but it's due to the mass flow rate of the engine. It has the same volumetric flow, but because Hydrolox is less dense the mass flow drops, where Kerolox has a higher density and thus higher mass flow, which is enough to give it more thrust with a lower Isp.

I know H2 has less thrust but I didn't think it was that low. Does that seem right? Or am I way off?

Edited July 10, 2014 by Rayder

[NathanKell]

I guesstimated that hydrolox engines have 75% of the TWR of kerolox engines, which seems to fit decently. For this reason when changing engine configs, hydrolox configs have 75% of the thrust. But it's all an abstraction anyway; real engines, you can't just swap out a propellant mixture for a totally different one.* The LR-87 is pretty unique in that it has been run on all three major propellant types, but it had to be redesigned for each.

*well, presumably switching between Aerozine and UD25 wouldn't take much, other than changing pump RPM ratios. But certainly going from storable to cryo is a heck of a change.

The holding vdot constant leading to changing mdot *is* correct for the NTRs though; that's why, say, LCH4 has a higher thrust, and LANTR has higher yet.

[Rayder]

Ah fair enough. It was just a surprising difference that's all. But as you said in reality it's not as simple as swapping out one fuel for another. So my answer is propably right mathematically, but not correct practically. Ultimately it's a game and you gotta make it playable, right?

I'm ultimately coming up with a cycle that involves TAC Life support, where hydrogen and methane play important roles not just for fuels, but in byproducts and resources for electrolysis and the Sabatier. Ultimately I'd like the methane generated from a Sabatier to be useful and you could use it as fuel for service modules, or something. The hydrogen could be flown up to support the process, or just fly up water and electrolyse it, providing oxygen for the crew and hydrogen to keep the methane production going.

This mod has helped a lot though, and is really handy for linking these resources together.

[SpacedInvader]

Is it possible to define two different tanks within a single part, or perhaps two types of tanks within a single volume? The reason I'm wanting this is so that its easier to define the life support portion of a service module. As it's currently set up, to add life support to the service module tank, you've got to manually calculate each input and output resource amount, resulting in 6 manual entries for a single module. I think it would be much easier to define a LifeSupportCC tank and then also a ServiceModule tank, allowing the former to automatically contain all of the necessary amounts and then the latter can be dedicated to electric charge, RCS fuel, and engine fuel.

[Guest]

I guesstimated that hydrolox engines have 75% of the TWR of kerolox engines, which seems to fit decently. For this reason when changing engine configs, hydrolox configs have 75% of the thrust. But it's all an abstraction anyway; real engines, you can't just swap out a propellant mixture for a totally different one.* The LR-87 is pretty unique in that it has been run on all three major propellant types, but it had to be redesigned for each.

Try using flow rate for figuring out TWR. Say, you've got a kerolox enigne configured. From Isp and thrust you can calculate the mass flow rate, which is proportional to your fuel pipe's cross section and fuel density. When reconfiguring the engine, the fuel pipe doesn't change (and thus the cross section stays the same), but the density does. That would allow you to calculate the new mass flow rate. Knowing Isp, you can use this to figure out how much TWR will drop. LH2 is much lighter than kerosene, so something tells me that it's gonna be more than 75%.

[NathanKell]

SpacedInvader: I actually just had this discussion about multiple-tanks-per-part on IRC. There's a *ton* of RF/MFT logic (and functionality) that depends on only one tank per part. Consider this: how should the two tanks interact in terms of setting basemass? Right now, it's simple: you just set the part's mass based on the basemass + base tank masses. But with two tanks (with varying basemass and base tank masses) it gets quite complex. I'm always open to pull requests, but this is not high on my list of stuff to do myself because it will require a lot of rewriting.

Dragon01: If you read my above post (again, I guess, since you quoted it), you will see that I already answered this. Changing configuration for an engine does not mean just switching feed lines. It means "what would an engine of the same mass and efficiency have in the way of performance statistics with this fuel."

[SpacedInvader]

SpacedInvader: I actually just had this discussion about multiple-tanks-per-part on IRC. There's a *ton* of RF/MFT logic (and functionality) that depends on only one tank per part. Consider this: how should the two tanks interact in terms of setting basemass? Right now, it's simple: you just set the part's mass based on the basemass + base tank masses. But with two tanks (with varying basemass and base tank masses) it gets quite complex. I'm always open to pull requests, but this is not high on my list of stuff to do myself because it will require a lot of rewriting.

I figured it would end up being something like that. I guess, I'll just have to do it manually.

[thefeeblespark]

Sorry if this has been answered before but... I get the menu for the fuel tanks but not the engines, so I can't change what propellent it uses like in the picture on the OP. I'm running linux but I don't think that changes anything. Same thing with the RCS ports. Am I missing something? The engines don't have the same GUI as the tanks, so I'm confused.

What I've tried:

Clicking on the part in the action group menu

Clicking on the name above the actions like in the picture

Praying to everything holy

Sacrificing calf

Searching google and Youtube

Sobbing

Help would be greatly appreciated

[NathanKell]

SpacedInvader: yeah, sorry...

thefeeblespark: did you install a set of engine configs, as the install instructions mention? See the OP/readme for install instructions, and the second post of this thread for links to engine config packs.

[thefeeblespark]

I feel like an idiot

Thanks for that. Can't wait to use this MOD

[Starwaster]

http://s3.amazonaws.com/data.tumblr.com/LMCn3DOdHik5od30Q5YNSYSao1_1280.png?AWSAccessKeyId=AKIAI6WLSGT7Y3ET7ADQ&Expires=1405149203&Signature=niI46XCFaoU9I0YVZzMKGY21JyU%3D#_=_

I feel like an idiot

Thanks for that. Can't wait to use this MOD

Even so, a few more calves might not be remiss...

[SpacedInvader]

So I'm building an orbital refueling station that is going to serve as the assembly / jumping off point for long duration interplanetary missions, as well as a stopover between Earth and the Kethane base I'm going to be building on the Moon. Anyway, the question is, what fuel(s) should I configure it to carry? Since each tank must be configured prior to launch, I want to make sure that I'm supplying the proper fuels for such trips. I should also point out that I've not yet discovered any of the more advanced propulsion methods (Nuke, Ion, Plasma, etc.), though nukes at least are next on my list. The station is quite modular so I'm not really locked into anything once its up in orbit, but it feels wasteful to launch a tank and then never really use it.

[Starwaster]

So I'm building an orbital refueling station that is going to serve as the assembly / jumping off point for long duration interplanetary missions, as well as a stopover between Earth and the Kethane base I'm going to be building on the Moon. Anyway, the question is, what fuel(s) should I configure it to carry? Since each tank must be configured prior to launch, I want to make sure that I'm supplying the proper fuels for such trips. I should also point out that I've not yet discovered any of the more advanced propulsion methods (Nuke, Ion, Plasma, etc.), though nukes at least are next on my list. The station is quite modular so I'm not really locked into anything once its up in orbit, but it feels wasteful to launch a tank and then never really use it.

It should be configured for the fuel tanks of propellants that that ships docking there will need with enough storage space for the output of kethane converters. You should have a better idea of your needs than any of us though..

Yes, plan for resources that you havent the technology to use, but as you say you're planning around modularity then you have leeway.

word of advice: reinforcing struts on tanks going up dry. They will undergo increased stress that wont be apparent dry. especially the long kethane tanks. I suspect because of their colliders. You dont want your station shaking itself apart the firstntime your mining ship transfers kethane over.

I speak from experience on that.

[NathanKell]

Try to send up tanks at least partially full; dry tanks are very light and will probably break your craft. This is due to the joint system: a light part between two heavy parts is liable to break the joints at both ends.

[SpacedInvader]

It should be configured for the fuel tanks of propellants that that ships docking there will need with enough storage space for the output of kethane converters. You should have a better idea of your needs than any of us though..

Yes, plan for resources that you havent the technology to use, but as you say you're planning around modularity then you have leeway.

word of advice: reinforcing struts on tanks going up dry. They will undergo increased stress that wont be apparent dry. especially the long kethane tanks. I suspect because of their colliders. You dont want your station shaking itself apart the firstntime your mining ship transfers kethane over.

I speak from experience on that.

Try to send up tanks at least partially full; dry tanks are very light and will probably break your craft. This is due to the joint system: a light part between two heavy parts is liable to break the joints at both ends.

I do have experience with lighter parts breaking... I tend to use small conic tanks on the bottom of larger diameter cylindrical tanks to make them look nicer and every now and then the smaller tank just blasts off through the larger tank when I ignite the engine its attached to.

As for the tanks I'm putting into this station, they won't be Kethane, but fuel / oxidizer only as the Kethane tanks will be either on the surface of the Moon or in orbit there. That all being said, the question was more regarding which types of fuels are best for long duration storage and for long duration missions. It seems that the most realistic propellant to be able to extract from other places in the solar system would be hydrolox in the form of electorlyed water, but LH2 seems like a bad choice due to its cryogenic nature. On the other hand, production of complex molecules like MMH or UDMH seem like they shouldn't be possible until much later tech levels, so I'm kind of caught between the two sides, if that makes any sense.

PS: On a side note, it might be interesting to force the kethane converter in RF to function based off tech levels this way...

[Starwaster]

I do have experience with lighter parts breaking... I tend to use small conic tanks on the bottom of larger diameter cylindrical tanks to make them look nicer and every now and then the smaller tank just blasts off through the larger tank when I ignite the engine its attached to.

As for the tanks I'm putting into this station, they won't be Kethane, but fuel / oxidizer only as the Kethane tanks will be either on the surface of the Moon or in orbit there. That all being said, the question was more regarding which types of fuels are best for long duration storage and for long duration missions. It seems that the most realistic propellant to be able to extract from other places in the solar system would be hydrolox in the form of electorlyed water, but LH2 seems like a bad choice due to its cryogenic nature. On the other hand, production of complex molecules like MMH or UDMH seem like they shouldn't be possible until much later tech levels, so I'm kind of caught between the two sides, if that makes any sense.

PS: On a side note, it might be interesting to force the kethane converter in RF to function based off tech levels this way...

Trivia note: In the Space Odyssey books (2001 / 2010) Discovery is known to have carried ammonia as propellant for its nuclear drive which is why it didnt all boil off before Leonov arrived at Jupiter.

[Raptor831]

Technical question for you all: For the stockalike config I have one set for the Space Shuttle Engines linear aerospike. Only problem is that the part is using two ModuleEngineFX modules. So, my config only applies to the first. If you set it with indexes in MM (i.e. @MODULE[ModuleEngineFX],0 and @MODULE[ModuleEngineFX],1) only the first one will change fuel types in the VAB/SPH. Is there any way to use both "engines" with variable fuels?

I could simply restrict that engine to hydrolox (which would be appropriate) and that would work, but tech levels still wouldn't work unless I just set it to TL7. I believe that dtobi has two separate transforms for each "engine" within the part, so I don't know if I can nuke the ModuleEngineFX nodes and start over without actually using two nodes (which just gives me the same issue). I'm hoping you all will have some ideas.

[NathanKell]

ModuleEngineConfigs supports only one engine module per part. I know that's bad, and it needs to be fixed, I just, err, haven't yet. It should not be that hard to change it to support 2 engines per part, but no more than that would be easy, and there'd still be some hacks to get that to work.

For now you can try duplicating the Effects and telling the Effects to use the exhaust transforms (1 each), and then use only one ModuleEnginesFX and have it use the gimbal for its thrust transform.

[SpacedInvader]

ModuleEngineConfigs supports only one engine module per part. I know that's bad, and it needs to be fixed, I just, err, haven't yet. It should not be that hard to change it to support 2 engines per part, but no more than that would be easy, and there'd still be some hacks to get that to work.

For now you can try duplicating the Effects and telling the Effects to use the exhaust transforms (1 each), and then use only one ModuleEnginesFX and have it use the gimbal for its thrust transform.

Modder-ator?

[Raptor831]

ModuleEngineConfigs supports only one engine module per part. I know that's bad, and it needs to be fixed, I just, err, haven't yet. It should not be that hard to change it to support 2 engines per part, but no more than that would be easy, and there'd still be some hacks to get that to work.

For now you can try duplicating the Effects and telling the Effects to use the exhaust transforms (1 each), and then use only one ModuleEnginesFX and have it use the gimbal for its thrust transform.

Thanks for the tips. I seem to have a config that works now.