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Ice, oxygen, water and vroom juice.

Discussion in 'General' started by Dusty Lens, Mar 20, 2015.

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This last post in this thread was made more than 31 days old.
  1. Dusty Lens Trainee Engineer

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    Hi everyone!

    So, man, I am super stoked about pressurization. Even without practical use I've often found that infrastructure needs are a fantastic tool for shaping creativity. Prepping a ship up for pressurization has been a treat.

    But what I'm primarily wondering, and I figured the forum warrior central would be the best crowd to ask, is if Keen has made any strong gesture towards an obvious correlation between processing this new resources, refining this new resource, tanking this new resource and shooting it out of those engines we've been plastering all over our ships.

    The current 'reactor drive' is all good and well. But has there been any indication that we're moving towards a fuel system in tandem with the recent development towards buttoning up our ships?
     
  2. Far-Seeker Trainee Engineer

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    I have not heard anything about revamping production, but I'm sure there will be additions and changes before the end of Alpha.

    However if by "vroom juice" you mean chemical rockets, for in-space propulsion that would actually be a big step backwards. This is because the specific impulse (the amount of propulsion produced per unit mass of fuel) of both solid and liquid chemical rockets are so much lower than the electrically powered plasma engines the game's current thrusters are based upon. I could see methane & diesel engines(the fuel can be made from non-petroleum sources) for use on planets with oxygen atmospheres. However, if you had to produce the oxygen as well as the to use a combustion engine, there really wouldn't be an advantage over an electric motor with a small fission reactor.
     
  3. aRottenKomquat Apprentice Engineer

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    While the thrusters we have now have a high specific impulse, I wouldn't mind seeing liquid-fuel rockets. They'd be far less efficient because of the low specific impulse, and would burn through fuel/propellant pretty quickly, but at least in today's world chemical rockets have a far higher raw thrust than plasma or ion thrusters so they're much more powerful and provide better acceleration.
     
  4. Far-Seeker Trainee Engineer

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    In the real world electrically powered thrusters have been used in actual space missions for only about two decades. The game is set in 2077, by that time these type of thrusters wold have had almost the same opportunity for refinement as modern chemical rockets. So whose to say the gap between them wold still be that great. Besides devoting more than 2/3rds of your vehicle's mass JUST to get about an hour of maximum thrust is so 20th century! ;)
     
  5. Echillion Senior Engineer

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    And a far bigger bang!
     
  6. Dusty Lens Trainee Engineer

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    As I'm not entirely familiar with the 'lore' behind SE's various mechanics. What is our actual propellant? I was more referring to using ice harvesting as a form of collected material to serve as ion fodder for a plasma engine than trying to craft some kind of chemical engine.
     
  7. Far-Seeker Trainee Engineer

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    My understanding is that the thrusters are based upon the VASIMIR ( http://en.m.wikipedia.org/wiki/Variable_Specific_Impulse_Magnetoplasma_Rocket ). It uses a noble gas like Argon or Xenon for the actual propellant, first ionizing it to form the plasma than using electromagnetic fields to accelerate, and possibly direct, the flow. However there are other tyes of plasma drives SE thrusters could be based upon, see : http://en.m.wikipedia.org/wiki/Plasma_propulsion_engine.
     
  8. Urablahblah Apprentice Engineer

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    Well IIRC, way back in SE's history Marek stated the thrusters are ion thrusters. Real ion thrusters use xenon as fuel partially because of its high density and low reactivity. The components of ice (oxygen and hydrogen obviously) are both highly reactive and nearly an order of magnitude less dense.

    Even though ion engines' ISP is incredibly high, an issue is their thrust capabilities. Modern ion engines are comparable to a car that takes two days to accelerate from zero to 60 mph (according to Wikipedia). Chemical rockets obviously don't have this problem.

    I am of the opinion that chemical rockets belong in SE along side their unrealistically fuel-less ion engines. Missiles, planetary launch systems, and large super-capitol ships would all benefit from having a high-thrust, fuel-consuming engine.


    Or we can start the discussion of nuclear thermal rockets. Those work too.
     
  9. Far-Seeker Trainee Engineer

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    The only reason why I think the SE thrusters are based on plasma drives is that they do physical damage. Technically all plasma thrusters are ion thrusters but not all ion thrusters use plasma (http://en.m.wikipedia.org/wiki/Ion_thruster). A thermally generated plasma based system like the VASIMIR will have a significantly hotter exhaust than a Hall Effect Thruster, though both are propelled by ions.

    Also I think the thrusters are "magical" only because Keen hasn't implemented a way to extract propellant for them. While all types of ion thrusters require far less propellant (by mass) than, we should eventually have to have tanks of it on our ships.

    Just a note I am being carefull to use the word propellant when discussing ion propulsion. This is because their fuel, as in the energy source like gas in a car, is the electricity that is already accounted for in the game. In contrast, both liquid and solid chemical rockets' generally rely on burning their fuel to provide both the propellant and the energy to accelerate it.
     
  10. Kuu Lightwing Senior Engineer

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    SE thrusters are magic. They don't use any propellant - only electric energy.
     
  11. Tyriosh Apprentice Engineer

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    Isn't it so that ion thrusters have some kind of propulsion mass, for example xenon, that gets ionized and brought to high speed. But doesn't this mass long for several years? Or am I wrong here. I mean that you don't need to have fuel tanks etc., just cause it longs for decades.
     
    Last edited by a moderator: Mar 21, 2015
  12. Knsgf Junior Engineer

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    This is true only for tiny unmanned probes with miniscule thrust. Full-sized ships are totally different story -- merely accelerating a 15,000,000 kg ship from 0 to 100 m/s with ion engines would consume about 7,500 kg of reaction mass, which is hardly a negligible amount.
     
    Last edited by a moderator: Mar 21, 2015
  13. NutterChap Apprentice Engineer

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    Very excited about this update INDEED! :)

    The other reasons to get excited is this:

    2 H2O --> O2 + 2 H2

    If we make oxygen from ice, we have residual hydrogen.

    (Possibly already said in previous posts but too lazy to read them all now)

    There is a metric brickton of things you can do with H2. Shoot it out of thrusters, refine till you have all heavy H2 and have your wicked way with it (hydrogen bomb?), or make heavy objects less affected by gravity by having tanks filled with H2. Furthermore, H2 is used in fuel cells... :D

    The possibilities have just become enormous!
     
  14. Urablahblah Apprentice Engineer

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    Honestly, I doubt the guys at Keen have thought through all this. It isn't KSP after all; parallels to real life equipment take a back seat to "fun" and what fits in the game.
    I hope this is something they plan. Talk about an engineering challenge! Can you imagine trying to run fuel (conveyor) lines to every engine?
    I wasn't aware of this subtle distinction. Thanks.

    My favorite use would be nuclear thermal engines. In real life they use liquid hydrogen as their fuel. They are a good balance between TWR and efficiency, especially for deep space craft.
     
    Last edited by a moderator: Mar 21, 2015
  15. tankmayvin Senior Engineer

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    I always assumed that SEs thrusters were nuclear thermal rockets because it's basically a neactor strapped to a hydrogen tank and a rocket nozzle. Which is more or less what we have in SE, just that the hydrogen supply has been abstracted.

    Now that we have ice, I think it would be neat if thrusters all gained liquid hydrogen inventory with the option to add extra tanks. Of course conveyoring would seriously screw everyone over, so make it convey like electricity.

    This oxygen update certainly gives you lots of hydrogen based options down the road.
     
  16. Cy83r Apprentice Engineer

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    Pah, nuclear thermal, why not take out the middleman and just make fission fragment drives? They even come in two styles.
     
  17. tankmayvin Senior Engineer

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    Quite true, I just figured that fragment drives would require coveyoring.
     
  18. goduranus Junior Engineer

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    Requiring some kind of fuel to be conveyored to the engines to get thrust would be pretty cool.
     
    Last edited by a moderator: Mar 21, 2015
  19. Far-Seeker Trainee Engineer

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    I would also relish more actual engineering challenges like this.

    Personally I wouldn't mind different types of engines, but keep in mind electric in-space propulsion has only been used sine the early 1970's, and the usage was rat her restricted until the 1990's. The game is set circa 2077, so ion and/or plasma thrusters would have almost as much time for development as modern chemical rocket engines have had. In contrast I don't see any groundbreaking improvements for chemical rockets, even after 60 years. I'm sure there would be refinements over our modern rocket engines, but 8 think most of the potential big leaps have already been made.

    I'm not as familiar with nuclear rockets, but they could be a worthwhile addition to the game if the have a different set of trade-offs involved.

    Also I suppose for planets and other places with relatively easily available oxygen, air and ground vehicles could use forms of combustion engines. As previously mentioned, generating oxygen from water yields a lot of hydrogen gas. Of course to burn it you have to expend the same amount of oxygen gas that was generated with the hydrogen! In my opinion it's not a good choice for a major fuel source for the asteroid belt, especially when we already have large scale electrical generation and electric motors and thusers as a viable alternative. Now for a place like Saturn's moon Titan, where there should be more water ice nearby (in Saturn's rings and on other moons) and the atmosphere is mostly methane and similar hydrocarbons, it might make more sense.
     
  20. tankmayvin Senior Engineer

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    No matter how much you develop ion engines and the like they are always going to have shitty thrust. This is a fundamental limitation of ion based propellants.

    Frankly, this game is space fantasy so the magical ion thrusters are fine. If we just pretend the thrusters currently implemented are magical super ion thrusters, then a conveyored super nuclear thruster (either nuclear thermal or fission fragment) that delivers much higher thrust/weight but burns U and maybe H2 at much higher rates would be a neat addition.

    You could "balance" it by the need to conveyor and the resource consumption costs.
     
  21. JoeTheDestroyer Junior Engineer

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    You pretty much summed up my opinion on the whole matter too.

    I'm completely against any kind of chemical rockets, but a thruster that consumes U and reaction mass (I would pick ice though, since that's already in game) offers a lot of gameplay opportunity. The tradeoff of weight/volume/surface area vs. resource consumption. The tradeoff of "free" thrust (solar/battery powered) vs. the requirement for precious uranium.

    Of course, all of this is moot with gravity drives on the table...

    Care to elaborate? I can't think of any reason why the basic idea "accelerate mass (ions) with an electric field" should have any more limitations than any other type of reaction drive.

    The equipment to accomplish that may be bulky, but that's an engineering problem that may well be overcome (to some degree) in the 60 years before this game occurs.
     
  22. REDSHEILD Junior Engineer

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    I'd love to have some chemical and nuclear thermal rockets, along with some ion thrusters to supplement the thrusters the game currently uses.

    That said, I'd much sooner have rails, compound blocks, and better netcode. Though I doubt new engines would get in the way of those, it's just I'd rather they be one of the small goodie bag updates instead of a major content one.

    Also, to clear up some misunderstandings I've seen in this thread, the thrusters in game are essentially Quantum Vacuum Thrusters, or QVTs. They're basically a form of ion thruster that uses the quantum foam of the vacuum as propellant. However they've got abysmally low thrust even compared to ion thrusters, with the trade off being a nearly infinite specific impulse* (ISP). They are a highly speculative technology at the moment so there isn't much in terms of descriptive science of their method of operation, though they fit the game's thrusters perfectly.

    *Technically the ISP would be infinite, however at this point the main limiter is not the propellant but the power source, thus whatever you use to fuel your power plant takes the place of propellant in the rocket equation, assuming you eject the spent fuel products.
     
  23. Knsgf Junior Engineer

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    Two words: vacuum arcing. You cannot rise voltage indefinitely.
     
  24. tankmayvin Senior Engineer

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    Well it's this and more: you can't arbitrarily increase the strength of the magnetic/electrical fields so the ion escape velocity is limited to some maximum eV because of vacuum arcing and similar.

    And because you are just flinging off ions, the volume and mass of the engine versus the thrust it can put out is terrible. You cannot arbitrarily increase the amount of ions, or their energy to compensate for that.

    So ion engines are always going to be net-net inferior to every other engine technology in terms of thrust output.

    ISP tells you only the efficiency in propellant usage, but doesn't tell you anything about how powerful the engine is.
     
  25. mhalpern Senior Engineer

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    I am not against Chemical rockets, so long as they aren't treated as a replacement for the thrusters we already have, they are great for gameplay. The difference I would want for Chemical rockets is make them cheaper, high thrust/weight ratio, require less power, and make sure that they can't constantly burn, great for weapons and launch assist modules, but quickly becoming dead weight as fuel would (hopefully) not go in cargo containers. Taking away the current thrusters, or enforcing that they use fuel of some kind, is exactly the kind of thing that may cause the very dead end scenario Keen has said early on they want to avoid.
     
  26. Lieu Trainee Engineer

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    Why the chemical rocket hate? Current thrusters are great for ships, but what if it's not a ship? What if I want something disposable for my guided missiles? ;) Something cheaper and lighter. Something that doesn't weigh 4 tons apiece and sucks up platinum ingots for a mere 100kN - and then I blow up the platinum. At least you can hybridise and use small ship thrusters, which do the job at a sane cost. But, you see... chemical rockets aren't quite obsolete yet!
     
  27. JoeTheDestroyer Junior Engineer

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    Ok, these I get.

    This one I don't get... Why not?

    I get that there are practical reasons why, but those only apply to today.

    Or it's energy efficiency, I know. It has greater importance when it's saving you fuel you have to haul out of a gravity well. But in this game, we're already out, so I have to debate how important a measure it really is.
     
  28. mhalpern Senior Engineer

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    THIS
     
  29. Far-Seeker Trainee Engineer

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    Honestly I was only considering vehicles and drones that would be used on a long-term basis. I was remiss in ignoring single-use applications like player-made guided missiles/torpedoes or disposable probes. In those cases I agree that chemical rockets would be a more inexpensive and potentially more effective solution.

    Oh for those of you citing vacuum arcing and electromagnetic field management as possible limitations to electric propulsion, all technologies have challenges and limitations. For instance, there is a maximum amount of energy you can get from any given chemical reaction and only a certain amount of that can feasibly be harnessed for propulsion in a chemical rocket. However, that didn't stop Goddard and Von Braun from trying getting the most performance possible with in those absolute and practical limitations! I invoke those names specifically because both men were working with rocket engines at a roughly analogous stage as the majority of electric propulsion technologies are at right now.

    Also there is amother type of plasma thruster, the magnetoplasmadynamic thruster
    ( http://en.m.wikipedia.org/wiki/MPD_thruster ), which could be built with today's technology that yield 2 to 25N of continuous thrust, and couldpotentially provide up to 200N of continuous thrust, and still have 40% to 60% efficiency, much more efficient than chemical rockets. The only thing keeping this from being used in an actual orbital or interplanetary mission is it would require hundreds of kilowatts of power, where as the current ion/plasma thrusters usually need 10kW or less. However, in the games hypothetical future with readily available nuclear reactors that is no longer an issue (and while I don't know if SE's reactors have realistic outputs, fission power is quite scalable and it's plausible that useful amounts of power could be generated by a reactor ~0.5m^3 in volume).
     
  30. Eternal Visitor Trainee Engineer

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    I would like to see boosted engines available, either as a separate block with fuel requirement or as an enhancement to the existing thruster blocks, like, have them work normally with no fuel, with an option to consume fuel to boost up to where the damper puts them.

    just my thought.
     
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