HoneyFox Posted August 16, 2013 Share Posted August 16, 2013 I made some buoyancy controller before by myself and i found that the actual buoyancy force applied onto a part is totally not same as the value i get from the partBuoyancy.effectiveForce. e.g. I have to apply 500kN+ of down-force to push a small vessel slowly to the sea-bed. and i find that at different depth, i need different down-force to make the sub hover in the water with zero vertical velocity, which leads me to guess that the buoyancy force is calculated by multiplying the current depth with some other coefficents, just like what they did with aero-drag forces (multiplying it with the mass of a part).I don't know if you can get the exact logic how KSP calculates the buoyancy and i'm curious. Link to comment Share on other sites More sharing options...
Zeroignite Posted August 16, 2013 Share Posted August 16, 2013 I don't know if this has been mentioned (I don't care to read through 65 pages) but I found a little bug pretty quick. The velocity control doesn't take into account parts of the ship that are rested on the ground and not weighing on the envelopes. It also doesn't take into account the lowering of mass, which is fair enough I suppose, but maybe it would be better to go by the velocity of the envelope parts if possible. Cool mod anyway.Working as intended. Setting target velocity to a small negative value is the correct way to use an airship anchor. Link to comment Share on other sites More sharing options...
SnappingTurtle Posted August 16, 2013 Share Posted August 16, 2013 I'm new to the mod, but wouldn't it be better for the velocity control to do what it says on the tin? Link to comment Share on other sites More sharing options...
kodemunkey Posted August 16, 2013 Share Posted August 16, 2013 So this is what my submarine is doing right now, i can't even get it to travel in any direction: Link to comment Share on other sites More sharing options...
Railgunner2160 Posted August 16, 2013 Share Posted August 16, 2013 2 words: More Ballast! You need more ballast tanks to maintain trim.... Link to comment Share on other sites More sharing options...
kodemunkey Posted August 16, 2013 Share Posted August 16, 2013 How about engines and control surfaces? Link to comment Share on other sites More sharing options...
taniwha Posted August 16, 2013 Share Posted August 16, 2013 Is it my imagination, or do FAR control surfaces not work particularly well underwater?Anyway, I have to say, those ballast tanks seem to be a tad small. You need to line up a lot of them to get some decent buoyancy. Link to comment Share on other sites More sharing options...
nhnifong Posted August 16, 2013 Share Posted August 16, 2013 Has anyone successfully mined kethane from the ocean floor with this yet? Link to comment Share on other sites More sharing options...
Hooligan Labs Posted August 16, 2013 Author Share Posted August 16, 2013 (edited) e.g. I have to apply 500kN+...Snjo may know more, but I found much the same insane force and have little idea how it works. The only thing that seems to scale it is depth in water, there is no other way to reduce buoyancy. That's why it had to be removed and replaced in my plugin.Working as intended. Setting target velocity to a small negative value is the correct way to use an airship anchor.Yeah, this seems to be the best way. I tried having it not count landed parts and it was too likely to overcompensate and crash. I also tried Tosh's PID controller that he used for his Gravity Canceler... As soon as the anchor touched to ground, the whole vessel's buoyancy was adjusted to 0 and it smashed down! So we stick with the simple control instead. I'm new to the mod, but wouldn't it be better for the velocity control to do what it says on the tin?Which mod? I think I have the airship one tuned pretty well but the submarine one is still in the works. Dealing with this much drag is not easy. It also does not take into account yet the buoyancy for crewed parts.So this is what my submarine is doing right now, i can't even get it to travel in any direction...I had this happen to after going to the tracking station and back. Is this what happened to you, or is it...2 words: More Ballast! You need more ballast tanks to maintain trim....Specifically more ballast tanks filled filled with buoyant air! Or more crewed components, they float too.Anyway, I have to say, those ballast tanks seem to be a tad small. You need to line up a lot of them to get some decent buoyancy.I wanted the initial one to be small enough to fit on most anything. Got a suggestion for a larger size / shape?Is it my imagination, or do FAR control surfaces not work particularly well underwater?I haven't tested. I don't even know how they react to negative altitude and high drag.Has anyone successfully mined kethane from the ocean floor with this yet? I would love to see that! Totally understand that this mod is glitchy and dangerous right now, but, you know, it's got to happen. Edited August 16, 2013 by Hooligan Labs Link to comment Share on other sites More sharing options...
taniwha Posted August 16, 2013 Share Posted August 16, 2013 I wanted the initial one to be small enough to fit on most anything. Got a suggestion for a larger size / shape?I suspect even a 10m3 unit would be a huge help. The basic shape of the current unit is pretty good, so maybe just longer and a little fatter. I might see if I can make a reasonable model. Link to comment Share on other sites More sharing options...
Hooligan Labs Posted August 16, 2013 Author Share Posted August 16, 2013 I suspect even a 10m3 unit would be a huge help. The basic shape of the current unit is pretty good, so maybe just longer and a little fatter. I might see if I can make a reasonable model.Sure! I can also do a 4x stretched radial, and maybe a simple Rockomax-sized inline.Given time, that is.Besides contributing models, anyone can help by:- Finding script to do fog in KSP.- Finding the ocean mesh and/or texture in KSP.- Finding exact cases which cause subs get stuck or explode sometimes. Link to comment Share on other sites More sharing options...
KhaosCorp Posted August 16, 2013 Share Posted August 16, 2013 Has anyone successfully mined kethane from the ocean floor with this yet? Yes...but not yet with this mod. I have mined off-shore via surface ship and submersible, though this will make the latter alot more managable. Link to comment Share on other sites More sharing options...
taniwha Posted August 16, 2013 Share Posted August 16, 2013 Has anyone successfully mined kethane from the ocean floor with this yet? Not yet. I was trying to make an ore mining sub, but while it was fine on the surface, it wanted to go either nose down or tail down (depending on iteration), and I couldn't steer it (due to FAR?). Link to comment Share on other sites More sharing options...
nhnifong Posted August 16, 2013 Share Posted August 16, 2013 (edited) Not yet. I was trying to make an ore mining sub, but while it was fine on the surface, it wanted to go either nose down or tail down (depending on iteration), and I couldn't steer it (due to FAR?).In the water, drag is the dominant force. put a centered fin or perhaps an intake on one end and then movement will always point that end backwards.EDIT, Actually since intakes drag changes based on the direction of travel (and in FAR, so do wings), having one on every side of your ship, all pointing inwards, should make your craft stable while moving in any direction because the intake facing most directly into the flow will end up at the rear. Edited August 16, 2013 by nhnifong Link to comment Share on other sites More sharing options...
BlazingAngel665 Posted August 16, 2013 Share Posted August 16, 2013 Can the drag code be changed? It seems to me that it is horribly unrealistic at the moment. It's water, not syrup. Link to comment Share on other sites More sharing options...
nhnifong Posted August 17, 2013 Share Posted August 17, 2013 Given the density of kerbin, It may well be a hyper-dense superfluid of liquid actinide metals. Link to comment Share on other sites More sharing options...
nhnifong Posted August 17, 2013 Share Posted August 17, 2013 Finally got around to installing it Hooligan Yes, you can mine kethane with it. Next step, a giant floating oil platform with a heli pad and a sinkable drilling rig connected with kethane! And tanker ships to transport the goods back to KSC to fuel the public's insatiable desire for the exploitation of Laythe! Link to comment Share on other sites More sharing options...
taniwha Posted August 17, 2013 Share Posted August 17, 2013 This is my attempt at an ore mining sub, but as I mentioned, the control surfaces seemed to have no effect.A grand total of 60 ballast tanks, just to be able to get ~11t of ore (has storage for ~22, but...), and she won't navigate . I suspect FAR doesn't adjust for being in water. Link to comment Share on other sites More sharing options...
Seeker89 Posted August 17, 2013 Share Posted August 17, 2013 This is my attempt at an ore mining sub, but as I mentioned, the control surfaces seemed to have no effect.A grand total of 60 ballast tanks, just to be able to get ~11t of ore (has storage for ~22, but...), and she won't navigate . I suspect FAR doesn't adjust for being in water.That's a beast of a sub... love it Link to comment Share on other sites More sharing options...
nhnifong Posted August 17, 2013 Share Posted August 17, 2013 Ok I've mastered sinking but now I can't make anything that floats :/What am I doing wrong? Link to comment Share on other sites More sharing options...
nhnifong Posted August 17, 2013 Share Posted August 17, 2013 How did you figure out how many tanks you needed? Just double it till it works? Link to comment Share on other sites More sharing options...
taniwha Posted August 17, 2013 Share Posted August 17, 2013 How did you figure out how many tanks you needed? Just double it till it works?Very simple math: for an object to float in a fluid, it must displace at least the same mass of fluid as the object's mass. ie, a 1t object must displace at least 1t of fluid. A ballast tank displaces 1.1t, so for water each tank can support 1.1t of ship (including the tank's mass). Link to comment Share on other sites More sharing options...
nhnifong Posted August 17, 2013 Share Posted August 17, 2013 Well I have encountered some kind of bug. No amount of ballast tanks has any effect. I need at least one to make the craft sink, but I'm using the deployable balloons to actually move up and down in the water.Probably because I'm using version 0.20.2 but I'm very attached to my save Link to comment Share on other sites More sharing options...
BlazingAngel665 Posted August 17, 2013 Share Posted August 17, 2013 Very simple math: for an object to float in a fluid, it must displace at least the same mass of fluid as the object's mass. ie, a 1t object must displace at least 1t of fluid. A ballast tank displaces 1.1t, so for water each tank can support 1.1t of ship (including the tank's mass).I'm not sure KSP hydrodynamics are that simple/sensible. Link to comment Share on other sites More sharing options...
nhnifong Posted August 17, 2013 Share Posted August 17, 2013 (edited) I've got a new strategy for mining on the ocean floor. Really long KAS cable dangling from an airship. Sure it's not a submarine, but it works! As long as the airship has at least one buoyancy tank, the probe can sink. As the prob gets close to the bottom, it fires a grappling hook and secures itself to the ocean floor. The ship above then switches to slightly positive buoyancy and pulls the cable tight, keeping the drill upright.Hooligan is there anything that can be done about the camera?There's not actually a kethane deposit here, I'm just testing it near KSC. Edited August 17, 2013 by nhnifong Link to comment Share on other sites More sharing options...
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