Is ISRU somewhat realistic?

[Red Iron Crown]

ISRU as a concept is reasonably realistic. Several real world proposals for missions to other planets involve creating fuel from local resources. So don't feel it's silly to make fuel on other planets, as it's somewhat likely the first real crewed Mars mission will do the same.

The implementation details in game are not very realistic, though. Very abstracted and simplified.

[Xavven]

On 5/21/2017 at 7:24 AM, StahnAileron said:

I meant in how they're implemented in KSP. Though it was a gameplay compromise I can understand. Still, infinite torque (over-time) eliminates the need for RCS rotation controls in most cases. (Massive builds still need them to turn within a reasonable timeframe.)

The way KSP implements reaction wheels so unrealistically still bothers me in my playthroughs. I mean, you can steer a rocket during ascent with a reaction wheel? C'mon... 
And RCS is too far into the tech tree, considering IRL even the earliest of manned space vehicles, Vostok and Mercury, had RCS.

As for ISRU, it's a real concept IRL and is theoretically possible. Splitting water into hydrogen and oxygen on a planet or moon is feasible and so is the idea of drilling for ice. You can also produce methane and oxygen from a carbon dioxide atmosphere. But then KSP takes the idea of ISRU and implements it in an unrealistic way-- by drilling for "ore". Technically there are some compounds that could be useful, but the amount of energy and equipment needed to process regolith (rocks) into fuel is silly compared to the aforementioned H₂O and CO₂ sources.

Edited May 23, 2017 by Xavven

[StahnAileron]

The "ore" bit is just the same abstraction as Liquid Fuel and Oxidizer: generics names applied to resources for the sake of simplicity. LF/O could be many things; it's not specified what exactly (seems many just assume RP-1 and LOX). "Ore", as much as a misnomer it can be (I associate it with metals first), is about as generic as you can get with mining. It's just one of those things I try not to think about too hard for a game like KSP.

Besides, it's not like this is the first time something got implemented in a sorta half-assed way. Abstraction of terminology is not compared to the lack of meaningful or poorly implemented gameplay mechanics in career mode, IMHO. But that a whole other can of worms I won't get into here.

[Alshain]

12 hours ago, Xavven said:

And RCS is too far into the tech tree, considering IRL even the earliest of manned space vehicles, Vostok and Mercury, had RCS.

Well the tech tree being ridiculous is another issue entirely.  It's not limited to RCS, it's everything.  They invent rocketry before inventing planes, or wheels.... or ladders.  However, reaction wheels are not really that unrealistic.  They are a bit overpowered in some scenarios, but bear in mind we've used reaction wheels to exclusively maneuver a 12 ton telescope for 27 years.  Build a 12 ton rocket with a Reliant and a Mk1 command pod (no active fins, no other reaction wheels, no gimbaling engines) and I think you will find it pretty tough to steer (it will steer but it will not react quickly).

Edited May 23, 2017 by Alshain

[Guest]

15 minutes ago, Alshain said:

Well the tech tree being ridiculous is another issue entirely.  It's not limited to RCS, it's everything.  They invent rocketry before inventing planes, or wheels.... or ladders.  However, reaction wheels are not really that unrealistic.  They are a bit overpowered in some scenarios, but bear in mind we've used reaction wheels to exclusively maneuver a 12 ton telescope for 27 years.

The Hubble's reaction wheels put out 0.82 Nm of torque maximum, it doesn't spin up like a 200 ton craft in KSP with four 1.25m reaction wheels can. We can continue to use those reaction wheels because the Hubble also has magnetic torque bars to desaturate the reaction wheels; it can't do that outside of LEO like a KSP craft can do outside of LKO (not to mention that one never needs to desaturate a reaction wheel in KSP...)

Edited May 23, 2017 by regex

[Alshain]

6 minutes ago, regex said:

The Hubble's reaction wheels put out 0.82 Nm of torque maximum, it doesn't spin up like a 200 ton craft in KSP with four 1.25m reaction wheels can. We can continue to use those reaction wheels because the Hubble also has magnetic torque bars to desaturate the reaction wheels; it can't do that outside of LEO like a KSP craft can do outside of LKO (not to mention that one never needs to desaturate a reaction wheel in KSP...)

Your talking about maintenance issues.  KSP doesn't have maintenance anywhere... even the Kerbals themselves have no maintenance.  That's just abstracted away.

Abstraction is one thing, but I disagree with @Red Iron Crown that ISRU is purely abstracted.   If we could only use it on certain planets, like Duna or Laythe... that would be abstracted.  But it's usable on the Mun, which makes it wholly fantasy.

Edited May 23, 2017 by Alshain

[Starman4308]

2 minutes ago, Alshain said:

Your talking about maintenance issues.  KSP doesn't have maintenance anywhere... even the Kerbals themselves have no maintenance.  That's just abstracted away.

Reaction wheel saturation isn't a maintenance issue, it's a basic physics issue where the wheels are treated as magic torque machines, not as devices to store and release angular momentum.

[Guest]

6 minutes ago, Alshain said:

Your talking about maintenance issues.  KSP doesn't have maintenance anywhere... even the Kerbals themselves have no maintenance.  That's just abstracted away.

The point being, KSP is not about realism because nods to realism take a backseat to whatever was considered "fun" at the time. Comparing things in KSP to things IRL and expecting to draw "realistic" comparisons between them will nearly always fail. Reaction wheels do exist IRL but they do not act in the same ways they do in KSP. ISRU can be used IRL but it is vastly different and much more complicated than in KSP. Fuel in KSP has no realistic comparisons to anything IRL save for its hsp and the effect it has on engine isp (IIRC engines are, now, based on the theoretical maximums of Aerozine50/NTO reactions). That's pretty much what this entire thread is about, building up some suspension of disbelief in order to enjoy a game.

Edited May 23, 2017 by regex

[Alshain]

Just now, regex said:

The point being, KSP is not about realism because nods to realism take a backseat the whatever was considered "fun" at the time. Comparing things in KSP to things IRL and expecting to draw "realistic" comparisons between them will nearly always fail. Reaction wheels do exist IRL but they do not act in the same ways they do in KSP. ISRU can be used IRL but it is vastly different and much more complicated than in KSP. Fuel in KSP has no realistic comparisons to anything IRL save for its hsp and the effect it has on engine isp (IIRC engines are, now, based on the theoretical maximums of Aerozine50/NTO reactions). That's pretty much what this entire thread is about, building up some suspension of disbelief in order to enjoy a game.

I don't disagree with that, but you are commenting on a comment of a comment of a comment that leads back to me saying ISRU is the least realistic thing in the game, and someone telling me reaction wheels are and then an ensuing discussion.  Nobody was saying KSP is about realism.  You are coming in at the end of a conversation and taking the last comment of context.

We were discussing what is least realistic and I guess that is up to opinion in the end.

[lajoswinkler]

17 hours ago, regex said:

The Hubble's reaction wheels put out 0.82 Nm of torque maximum, it doesn't spin up like a 200 ton craft in KSP with four 1.25m reaction wheels can. We can continue to use those reaction wheels because the Hubble also has magnetic torque bars to desaturate the reaction wheels; it can't do that outside of LEO like a KSP craft can do outside of LKO (not to mention that one never needs to desaturate a reaction wheel in KSP...)

That's why I use this.

https://spacedock.info/mod/879/Reaction Wheel Rebalance

It allows very fine tuning of the orientation. Stock values are just ridiculous and annoying and were a problem for me ever since I first started playing KSP. If I want wild spinning, I can use RCS.

[Guest]

5 hours ago, lajoswinkler said:

That's why I use this.

https://spacedock.info/mod/879/Reaction Wheel Rebalance

I just use Realism Overhaul with RSS because trying to correct everything else in stock KSP while suspending my disbelief of its fundamental problem just seems silly.

[Dr.LoveJoy]

ISRU being unrealistic is no different from the fact that we are literally bolting together components to make a rocket, tossing equipment on the exterior surface attached, as well the size of Kerbin vs its density.

Reaction wheels are so powerful because if you are steering with a joystick or keyboard, and using a normal computer, you generally won't have the ability to positively steer your spacecraft, even with RCS.

I don't think it is in scope for SQUAD to make the game more realistic per se, as that would be an incredibly huge amount of work.. work that the RO people are doing  very well.

Edited June 19, 2017 by Dr.LoveJoy