Welcome to Keen Software House Forums! Log in or Sign up to interact with the KSH community.
  1. You are currently browsing our forum as a guest. Create your own forum account to access all forum functionality.

Numbers for the hydrogen thrusters?

Discussion in 'General' started by AutoMcD, Oct 23, 2015.

Thread Status:
This last post in this thread was made more than 31 days old.
  1. AutoMcD Senior Engineer

    Messages:
    2,369
    I'm wondering if one of you script kiddies can quickly grab the thrust output and weight of these new parts for comparison to the traditional ion thrusters.

    Also I'm curious on consumption rates, how much volume the tank holds, how much H comes from 1kg of ice?

    ENGINEERING MINDS NEED TO KNOW
     
    • Like Like x 5
  2. Leadfootslim Senior Engineer

    Messages:
    1,300
    I did a rough test for a set of 8 small thrusters in a needlessly complicated pretty-looking array, compared against 8 small ion thrusters. All were attached to the same ship-brick, with one set turned off for each test.

    At a 5-second burn, the ion thrusters reached ~35 m/s, while the hydrogen hurled me forward to 108 m/s in the same time period. So that'd be roughly 3x the power? If so, I shudder to think what'll happen to the first ship that tries to land with ion thrusters...

    Edit: It appears my eyeballing was pretty close, if the numbers shown are right. 900 for sm. Hydrogen and 288 for sm. Ion is just about 3x the power. Those fuel consumption rates tho...
     
    Last edited: Oct 23, 2015
    • Like Like x 2
  3. kcjunkbox Senior Engineer

    Messages:
    1,131
    Just the block detail mod. It tells you all that info about the block before you place it. Then set both blocks on your tool bar and switch between them to see their details. Really useful mod!
     
  4. Spets Master Engineer

    Messages:
    3,214
    only have this for now

    Large Ship
    Small Hydrogen Thruster Max NForce - 900 kN
    Large Hydrogen Thruster Max NForce - 6 MN

    Small Ship
    Small Hydrogen Thruster Max NForce - 62 kN
    Large Hydrogen Thruster Max NForce - 400 kN


    Large Ship
    Small ION Thruster Max NForce - 288 kN
    Large ION Thruster Max NForce - 3.6 MN

    Small Ship
    Small ION Thruster Max NForce - 12 kN
    Large ION Thruster Max NForce - 144 kN
     
    • Like Like x 7
    • Informative Informative x 1
  5. Lt_Duckweed Apprentice Engineer

    Messages:
    417
    L̶o̶o̶k̶s̶ ̶t̶o̶ ̶m̶e̶ ̶l̶i̶k̶e̶ ̶l̶a̶r̶g̶e̶ ̶h̶y̶d̶r̶o̶g̶e̶n̶ ̶t̶h̶r̶u̶s̶t̶e̶r̶s̶ ̶n̶e̶e̶d̶ ̶a̶ ̶b̶i̶g̶ ̶b̶u̶f̶f̶.̶ ̶ ̶2̶7̶ ̶t̶i̶m̶e̶s̶ ̶t̶h̶e̶ ̶v̶o̶l̶u̶m̶e̶,̶ ̶9̶ ̶t̶i̶m̶e̶s̶ ̶t̶h̶e̶ ̶s̶u̶r̶f̶a̶c̶e̶ ̶a̶r̶e̶a̶ ̶o̶f̶ ̶a̶ ̶s̶m̶a̶l̶l̶ ̶o̶n̶e̶,̶ ̶b̶u̶t̶ ̶o̶n̶l̶y̶ ̶6̶.̶6̶7̶ ̶t̶i̶m̶e̶s̶ ̶t̶h̶e̶ ̶t̶h̶r̶u̶s̶t̶?̶ ̶ ̶N̶o̶ ̶t̶h̶a̶n̶k̶s̶.̶

    See bellow post.
     
    Last edited: Oct 23, 2015
  6. Lt_Duckweed Apprentice Engineer

    Messages:
    417
    Large Ship:

    Small Hydrogen Thruster T/W - 64.672
    Large Hydrogen Thruster T/W - 88.216

    Small ION Thruster T/W - 6.710
    Large ION Thruster T/W - 8.503

    Small Hydrogen Thruster T/W / Small ION Thruster T/W = 9.638
    Large Hydrogen Thruster T/W / Large ION Thruster T/W = 10.375

    A hydrogen thruster is about 10 times as powerful as a ion thruster, kilo for kilo.


    I think this speaks for itself.
     
  7. blizzerd Apprentice Engineer

    Messages:
    478
    do the hydrogen thrusters require a lot of energy?
     
  8. BlackUmbrellas Senior Engineer

    Messages:
    2,818
    Nope. Very little, even, less than normal thrusters.
     
  9. blizzerd Apprentice Engineer

    Messages:
    478
    GOOD makes em unique in a way

    i can already see the concepts of fighter craft with manoeuvring ion thrusters and hydrogen thrusters for speed.
     
  10. Cruzz999 Apprentice Engineer

    Messages:
    264
    Does those calculations include the weight of the Hydrogen tank?
    If not, how much does that weigh, and how does it impact the numbers?
    Ion thrusters wouldn't need it, multiple hydrogen thrusters might need more tanks, more weight in form of ice, etc etc.
    There's more to this than just 10x more thrust to weight.
     
  11. Lt_Duckweed Apprentice Engineer

    Messages:
    417
    One large ship hydrogen tank has a mass of 8161.6kg. Which is a bit less than 2 small ion thrusters. Aka, even if you have a tank for every small hydrogen thruster, you still have a better T/W ratio. It's late, but I'll run some fuel burn times tomorrow.
     
  12. ATalkingRock Apprentice Engineer

    Messages:
    396
    Yeah the large ship hydrogen thrusters need a buff. It looks like they forgot the size of the block and made the numbers accordingly. In other words it looks like they thought the large thruster was 3x2 like the large ion thrusters.

    The large hydrogen thruster is a 3x3x3 block which produces 6mN of force while 9 small thrusters will produce 900kN x 9 = 8.1mN. That's an entire 2mN of force extra. There's no incentive to use the large ship big thruster! Hope they buff it haha

    Please correct me if I misinterpreted the data listed above!
     
  13. Cruzz999 Apprentice Engineer

    Messages:
    264
    Thanks for the additional info regarding H2 storage weight.
    What's the H2 draw? Is it possible to run H2 thrusters directly off H2O electrolyzers (O2 generators)?
     
  14. AutoMcD Senior Engineer

    Messages:
    2,369
    I did actually do exactly this on a small ship, but the output is limited (Such as trying to run a large ion thruster from a small reactor). The experiment was actually to see if it would run off an H2 bottle, which did not happen. Seems like bottles are for jetpack only.
     
  15. Cruzz999 Apprentice Engineer

    Messages:
    264
    Okay. I'm still not able to test it out myself, could you try just adding a bunch of O2 gens to one small H2 thruster and see if you can get the H2 production up enough to run it at full power? Just to see if it's at all feasible.
     
  16. AutoMcD Senior Engineer

    Messages:
    2,369
    I will definitely figure out the output of o2 gen vs h2 thruster inputs, especially since the h2 tanks are so heavy. But I can't until tonight, maybe someone will have time today to figure it out.
    Ballpark is one will def run a small thruster or two but not much more than that.
    Also I think ice consumption is bugged, just going to worry about power levels and weight for now.
     
  17. Cronos988 Junior Engineer

    Messages:
    545
    Some interesting info from looking at the new CubeBlocks: The large oxygen generator has an ice to hydrogen ratio of 3, while the small one only has a ratio of 2; Both have an ice to oxygen ratio of 3 though, which makes this weird.

    Going by the ice consumption per second, the large oxygen generator produces 501 litres(?) per second, whereas the small one produces 166.

    There is also the new "GasProperties.sbc", which tells me that hydrogen has an energy density of 0,001556 mWh/L.

    So in a second, a large oxygen generator produces 779.556,00 Wh, or 799,556 kWh. A small one produces 258,96.

    Unfortunately I don't know what to do with these units now. My last physics lesson was in school, and that was a while back ;)

    Edit: So looking at wikipedia, what we have is the amount of energy that the oxygen generator produces, and the amount of force a thruster puts out. What we don't have is the energy to force conversion rate.
     
    Last edited: Oct 23, 2015
  18. Seagoon Trainee Engineer

    Messages:
    32
    Surely the ratio of oxygen to hydrogen produced by the generator would be 2 hydrogen to 1 unit of oxygen?
     
  19. Hiramas Apprentice Engineer

    Messages:
    121
    *wonders about the possibility of hydrogen fusion reactors instead of uranium fission*
     
  20. Knsgf Junior Engineer

    Messages:
    538
    I did some tests, and it looks that the energy density is about 3600 times less than units suggest. So it is actually in MJ/L.

    • Large grid/large size 6430 L/s ,
    • Large grid/small size 1100 L/s,
    • Small grid/large size 515 L/s,
    • Small grid/small size 110 L/s.
    Aside from single small/small thruster, none of them can be kept running by an oxygen generator.
     
    • Agree Agree x 1
  21. tankmayvin Senior Engineer

    Messages:
    2,863
    They burn fuel at a phenomenal rate.

    What limits the H2 thrusters is not the amount of fuel needed, but the volume that fuel takes up because of the titanic size of the H2 tanks, especially relative to small ships.

    Other than using them as afterburners (*hat tips to @Hesterry*), I think they are really balanced around short duration orbital burns rather than as a viable alternative to ions for ship maneuvering. This is ultimately probably a good design move.

    I think specialized ultra high accel designs might make use of H2, but with the meager speed cap you can't make full use of it. I don't think they are really an alternative to ions unless there is a major rebalance in fuel consumption or tank storage density.
     
    • Like Like x 1
  22. Cruzz999 Apprentice Engineer

    Messages:
    264
    On my way home now, my objective is clear. Stick a large fuel tank down, slam on a fuckload of ice converter thingys, (O2 generator seems.. Wrong now) and see what it takes to build a relatively fast ship with H2 sustainability.
    :pbjt:

    X*501/6600>1 gives us an X of 14. So 14 generators per small engine in each direction should work.

    Anyone wanna maths while I'm on the bus and tell me what the thrust to weight ratio I'd if you're lugging around on that much extra weight?
     
    Last edited: Oct 23, 2015
  23. thatguywithahammer Apprentice Engineer

    Messages:
    179
    Alright, time to do some science! Assuming the others are right about thrust and fuel flow, calculating specific impulse should be relatively straightforward. I have been known to get my units wrong, so take this all with a grain of salt. For example, the unit I solved for is Newton-seconds per kilogram. I'm pretty sure this is equivalent to exhaust velocity in meters per second (since imparting 5 Newton-seconds of momentum to a 1-kilogram mass will change its velocity by 5 m/s) but I could be wrong.

    (Grid size/engine size)
    Large/large: 13,180 (1345 sec)
    Large/small: 11,556 (1179 sec)
    Small/large: 10,970 (1119 sec)
    Small/small: 7,961 (812 sec)

    So it looks like there is some economy of scale here. In fact, the biggest engine is 65% more efficient than the smallest one.

    These numbers are much too high for chemical rockets. They do match the performance of a nuclear thermal rocket pretty well, though, especially considering their use of pure hydrogen as fuel.

    TL;DR: Look, guys! I can use Wikipedia!:pbjt:
     
    • Like Like x 2
  24. WarWyvern Trainee Engineer

    Messages:
    99
    A bit of a tangent: small ships now have working air vents, even though small armor blocks don't hold air. The most obvious implication is that it'll allow a small ship to replenish its O2 while in the appropriate atmosphere, but I wonder if they'll also be used as intakes for the hydrogen thrusters, improving the ISP. Making the thrusters bi-modal and more efficient in an oxygenated atmosphere would further cement their proposed role of an efficient landing, lifting, and maybe aircraft thruster while maintaining their current role of short-burning space combat boosters.

    If this turns out to be the case, then perhaps there will one day be an option to inject oxygen into the fuel mix, at a loss, of course, so that you are burning significantly more oxygen than you would pure hydrogen. If nothing else, this would allow us to better manage our ship's limited resources.

    This has probably been speculated elsewhere, but in case it hasn't, there's my tawdry theorizing. :)
     
  25. Cruzz999 Apprentice Engineer

    Messages:
    264
    If you mean what I think you mean (taking in hydrogen from the atmosphere for the h2 thrusters) I think you'll be disappointed. The amount of hydrogen in the atmosphere is very very low... That's just on earth though, I guess it could be different on other planets, but I doubt it. It's too light.
     
  26. drkrieger Apprentice Engineer

    Messages:
    407
    Small Hydrogen Thrusters (Large Ship) only require 1.70Mw. The Large Hydrogen Thrusters (Large Ship) requires 10Mw.

    In comparison (Large Ship):
    Small Ion Thruster = 3.60Mw
    Large Ion Thruster = 33.6Mw

    Large Thrusers do appear to be more efficient in terms of electricity use. Not sure on the fuel side of things.
     
  27. Bobylein Apprentice Engineer

    Messages:
    201
    Only if they release a cloud of deadly plasma when damaged.
     
  28. WarWyvern Trainee Engineer

    Messages:
    99
    I was thinking something more along the lines of a jet engine. Use the oxygen in the atmosphere to increase the temperature of the reaction while consuming a relatively small amount of fuel (specifically hydrogen, in this case). I guess I want these new thrusters to become the SE equivalent to SABRE rocket engines.
     
  29. thatguywithahammer Apprentice Engineer

    Messages:
    179
    Fuel efficiency seems to increase with size.
     
  30. drkrieger Apprentice Engineer

    Messages:
    407
    What do we need? RAM Jet engines.
     
    • Like Like x 1
Thread Status:
This last post in this thread was made more than 31 days old.