Thrust per kilo if you need to know!

Discussion in 'General Discussion' started by pachangas, Mar 1, 2019.

  1. StyxAnnihilator

    StyxAnnihilator Captain

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    Missing from the equation is the weight/mass of thrusters (and RCS's) needed to achieve the force. AND space to fit it, if to have it inside a hull.
    So then you find out how much force per KG a thruster gives.
    Then calculate in needed RCS weight.
    Oh, yes, then the size needed to fit it all, after finding the thrusters to use.
    Ouch, need so much space? Then maybe have to rebuild and recalculate it all.
     
    #21
  2. pachangas

    pachangas Lieutenant

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    This is just looking at thrust in Newtons (as displayed in your stats), the Kg mass of your vessel (as displayed in your stats) and the gravity of the planet you're on. It's a pretty simple equation, which is Newton's genius I guess.

    Block size is important from a design perspective, agreed - and can I just say, having a (large) CV thruster with an even block width is a pain from a vertical lift and symmetry perspective Eleon, but that's irrelevant from the calculation's perspective, where you're just looking at the mass of the thruster and what thrust it has.

    I approach it from the point of view that I'd like to be able to lift a maximum amount of mass. You can then add enough thrusters to achieve that lift and go from there.

    The calculation's accurate, the resulting design needs flexibility to adjust the implementation.

    As for RCS's, there's no simple calculation for the effect they have. It's based on rotational forces and the mass in a given plane. It doesn't seem to matter where the RCS is in a plane, but the mass in that plan is important.
     
    #22
  3. StyxAnnihilator

    StyxAnnihilator Captain

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    For me the OP calculation is just basic physics math, close to 2+2=4. Of course useful for those that have forgotten it or never learned it.

    Real equation that would be more useful is one that handles what I listed of some of the issues.
    Select a vessel type (CV/SV) and thruster and basic mass/weight and gravity and turning speed, then the equation give out minimum amount of thrusters, RCS's (T1 or T2) and volume.

    Now you can simplify a bit by creating a ratio between force:weight:volume. Then have a list of the different thrusters and their ratios, to select a mix.
    What can complicate even more are if to handle directions and speed, that the vessel should be able to do a minimum speed in a direction. Simplify by calculate for 1 direction (without gravity) and multiply by 5, then add the gravity one, maybe.

    Can simplify by give the volume of all thrusters and RCSs needed, with a minimum added weight for a basic sized vessel.
    Good luck for those that bother create such equations.
     
    #23
  4. Furious Hellfire

    Furious Hellfire Rear Admiral

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    Another tale of gravity woe !
    This is what happens when you don't do at least a little bit of research into gravity and thrusters :D

    One time in a server I went into a random planets atmo for the first time, I believe it was the "where am i" server, and once I got in the atmo i stopped to check map, so I was maybe only 100m from orbit.
    My ship was class 1 maybe 2 fuel tanks maybe 1.
    I close the map and noticed my generator stat on the hud, very high usage, and then the fuel, 1 or2 minutes 0.o then i realised gravity was over 3g and i hit space bar to go up and get out because I realised my engines were working overtime to hold me in place.....
    With space bar held my fuel became 4 or 5 seconds to burn full tank or something crazy.

    I was lucky to have a small stack of fusion cells in my invent because I ran out of fuel twice and nearly a third time with no reserve in that short space of 100m to orbit, just from holding space to get out, but I made it and with the last push of fuel I had left in my invent.

    That was the first time empyrion made me sweat it was a very gripping moment and rather epic to go through lol and to survive it, hell yeah a fire up the stogie cigar moment.

    On the ground below me later when i returned in more suitable vessel, turned out to be the most devastating group of heavily armed POI I ever saw in a online playfield at the time and to think my class 1 ship was ready to run out of fuel and land in the middle of them haha oh the joys.
     
    #24
  5. H.P. Strangelove

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    I mainly just reference some spreadsheets. Some of the info isn't as useful but can be helpful at times.

    thrs1.jpg
     
    #25
    Last edited: Mar 15, 2019
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  6. geostar1024

    geostar1024 Rear Admiral

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    The ship size is even more important due to the current moment of inertia calculation that effectively spreads the ship's mass uniformly through the bounding box of the ship. This is the reason that adding a single 1 kg light that expands the bounding box of a ship will drastically reduce its turning rates.
     
    #26
  7. pachangas

    pachangas Lieutenant

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    That's what I mean. Whilst it's really hard to achieve, you seem to get the best turning rates when the RCS are equally distributed along the axes around the centre of mass.
     
    #27
  8. geostar1024

    geostar1024 Rear Admiral

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    Err, what? Neither RCS placement nor a ship's actual mass distribution affects its turning rates right now.
     
    #28
  9. pachangas

    pachangas Lieutenant

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    By way of example, a little unrealistic, but it demonstrates what I mean when I say that the location of the RCS in relation to the centre of gravity changes its efficiency:

    The following has: P: 3444 R: 84 Y: 84
    upload_2019-3-20_18-32-30.png


    The following has: P: 1378 R: 81 Y: 84
    upload_2019-3-20_18-34-5.png

    The following has: P: 689 R: 77 Y: 84
    upload_2019-3-20_18-34-27.png
     
    #29
  10. geostar1024

    geostar1024 Rear Admiral

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    The size of the ship is increasing, which in turn increases the ship's moment of inertia. If you want an actual comparison, add a few extra blocks to each design to make it so that the ship size stays constant, and you should find that the turning rates stay the same no matter where you move the RCS within the bounding box.
     
    #30
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  11. pachangas

    pachangas Lieutenant

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    Ah right, I see what you mean now. I guess that's the easy option to code.
     
    #31

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