Jovus
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Posts posted by Jovus
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Pretty much as title. It has been a good long while since I last ran KSP, and a good long while before that since I actually seriously played.
What mods are essential these days? Back when I last played it was things like Kerbal Alarm Clock, Kerbal Engineer or MechJeb (I preferred the former, not to inflame old rivalries), and your docking assitant of choice (mine was Navyfish's). How about these days?
For that matter, what mods would you recommend for a vanilla+ experience, whether functional or graphical?
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Hello @ferram4,
I went back to college to get a PhD in Physics in large part because of your work, and eventually settled into CFD.
Way back when I first became aware of FAR I was impressed, and it ignited a love for aerodynamics (specifically around rockets and re-entry) that I had never had before.
Now that I'm much more familiar with the problems involved and the methods used to solve them, I'm even more impressed. Flabbergasted, is the word, that you've made an acceptable-accuracy aerodynamic calculator for almost arbitrary shapes that works in real time on a home computer to any accuracy while that same computer is also running everything else KSP does.
Kudos to you. Greatest kudos.
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Oi. Yes, it is.
Density was used to find the radius of the 'disk' (cylinder). So the radius is off by a factor of 103, which means acceleration due to gravity on the surface of the sphere is off by a factor of 106, and centrifugal force is off by a factor of 103; but still, the disk won't fly apart under the force of its own rotation. -
On 12/1/2017 at 4:46 AM, Green Baron said:
I admire your eagerness :-) I should add that irl a disk of that mass cannot exist, it'll cramp into a sphere and/or the outer parts fly away if it rotates. Or the laws of gravity must be changed for some of the assumptions to work, they partly stay intact for others.
I have the following examples: Density of the sphere cannot be the same as that of a disk as the pressure is missing. Iron in the earth's core is compressed to >13g/cm³. Also angular momentum of a disk is different than that of a sphere as more mass is out and away from the center. The mass of a sphere can, for ease of calculation, be regarded as being concentrated in a point, for a disk that doesn't work.
Edit: moment of inertia of a disk is m*r²/4 ?
Or did i get something wrong ?I didn't: you took the moment in z-axis, but it should be in x/y-axis as you want to calculate the forces on the rim of the thing. Also, i am not sure if assuming the disk as being represented by a point mass is correct in this context. It's really not ... ?Well, yeah, the hypothetical is absurd. It would definitely condense into a sphere; that's in fact what actually happened according to our current models. (Though it may take a good long while on a human time-frame.) However, I should point out that the whole point about centrifugal force being lower than gravitational force was to see whether this construction would immediately fly apart at the rim, which it wouldn't due purely to mechanical forces of the object itself. (In 'reality', of course, perturbations from the other celestial bodies would take care of it pretty quickly.)
As to the moment of inertia: no, you want the moment of inertia around the z-axis. Moment of inertia is relative to the axis of rotation, and the axis of rotation for this disk is through the z-axis (that is, I took it as rotating like a top or the disk in a gyroscope, instead of like a coin spun on a table).
As for the rest, I was explicitly not treating of anything other than the barest, simplest-order mechanics. You can if you like. I admit there would be other effects; I just don't care enough about the question to work them out.
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On 11/27/2017 at 4:22 PM, Jovus said:
Just for funsies:(
Gravitational force at the surface of the Earth (in 'disk' configuration):
GMm/r^2M = 5.972 × 1024 kg
Now then, the average density of the Earth remains unchanged at 5.51 g/cm³ or 5.51 x 10-9 kg/m3 (because I said so)
Assuming the disk is a smooth disk with h = 10m, that makes Vdisk = 2 πhRdisk = 3.29 m3, so Rdisk = 5.237 x 1014 m2
G = 6.67408 × 10-11 m3 kg-1 s-2
so F (on a mass at the 'rim' of the Earth) = m*(1.45m/s2)
Or 1.45m/s2) is our new 'g'
To be continued when I get home/feel like itNow continued.
First, found a couple stupids. We assume the density of the Earth, and therefore the volume of the Earth, is unchanged. Modeling the Earth as a perfect sphere of uniform density (close enough for our purposes), we find:
VEarth = (4/3)*π*Rearth3= (4/3)*π*(6.371 x 106 m)3 = 1.083 x 1021 m3
Now we can say Vdisk = VEarth = 1.083 x 1021 m3 = 2πhRdisk2 , or Rdisk = sqrt((1.083 x 1021 m3)/2π(10m)) = 4.152 x 109 m which is a lot more reasonable.
so the force on a mass m at the surface of the disk (on the outer edge, not on one of the faces) is Fgrav = GMm/Rdisk2 = m*(2.3 x 10-5 m/s2)
So our new 'g' (acceleration by gravity at or near the surface) is 2.3 x 10-5 m/s2
Putting that into perspective, gPluto = 0.62 m/s² and gGilly = 0.049 m/s2, though I find those numbers suspect. (The Pluto-Charon system has a barycentre outside itself, so gPluto necessarily depends heavily on where you are on the planet, and Gilly is lumpy and small, so the same can be said of it.)
Since the Earth didn't lose any mass in the transition, angular momentum should be conserved. Since the disk is spinning through the same axis, and it's also a prinicpal axis of the disk, the calculations for moment of inertia are simple:
LEarth = IEarth * ωEarthLdisk = Idisk * ωdisk
LEarth = Ldisk so
IEarth * ωEarth = Idisk * ωdisk
Moment of inertia of a sphere is 0.4*mr2, so IEarth = (0.4)*(5.972 × 1024 kg)*(6.371 x 106 m)2 = 9.696 x 1037 kg*m2
Moment of inertia of a disk is 0.5*mr2, so Idisk = (0.5)*(5.972 × 1024 kg)*((6.371 x 106 m)2 = 5.148 x 1048 kg*m2
TEarth = 1 day = 86400 sec, so ωEarth = 2π/86400sec = 7.272 x 10-5 rev/sec
IEarth * ωEarth = Idisk * ωdisk so ωdisk = (IEarth/Idisk) * ωEarth = ((9.696 x 1037 kg*m2)/(5.148 x 1048 kg*m2)) * (7.272 x 10-5 rev/sec) = 1.370 x 10-10 rev/sec
Which means that a day on the disk is roughly twice as long. (hah! That's very wrong. But 'twice' is revealing to the way astrophysicists think, so I'm leaving that in.)
Tdisk = 2π/ωdisk = 2π/(1.370 x 10-10 rev/sec) = 4.587 x 1010 sec, or 5.31 x 105 Earth days.
Now then, the force from gravity at the rim of the disk as shown above is m*(2.3 x 10-5 m/s2) (where m is the mass of a particle on the rim), but
centrifugal force on a spinning object is -m*ω x (ω x r). The cross-products, on a disk spinning through the centre around the z axis, resolve to radial out, and
Fcent = -m*ωdisk2*Rdisk = m*(1.370 x 10-10 rev/sec)2*(4.152 x 109 m) = m*7.790 x 10-11
Compared to Fgrav = m*(2.3 x 10-5 m/s2), we can say that this object wouldn't spin itself apart.
So much for simple mechanics. I'll leave worrying about interactions with other bodies, weather, effect on life, thermodynamic effect of injecting enough energy to accomplish this feat, etc. to other minds.
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Just for funsies:(
Gravitational force at the surface of the Earth (in 'disk' configuration):
GMm/r^2M = 5.972 × 1024 kg
Now then, the average density of the Earth remains unchanged at 5.51 g/cm³ or 5.51 x 10-9 kg/m3 (because I said so)
Assuming the disk is a smooth disk with h = 10m, that makes Vdisk = 2 πhRdisk = 3.29 m3, so Rdisk = 5.237 x 1014 m2
G = 6.67408 × 10-11 m3 kg-1 s-2
so F (on a mass at the 'rim' of the Earth) = m*(1.45m/s2)
Or 1.45m/s2) is our new 'g'
To be continued when I get home/feel like it -
Also, maps of the near side were better, so it was a lot easier to choose and aim at good-looking landing spots.
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Nope. Wouldn't fit in my freezer, and the warranty doesn't last that long anyway.
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The recent historical answer has been spy satellites. Some of thos suckers are really big.
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Also, I could easily see DLC covering areas of the game that people want but that have been off the table for a while now, all without changing anything truly core to the game and without harming craft intersharing by releasing new parts.
For example:
- New Planets and moons (we finally get that second gas giant)
- Storyline content (either sandbox puzzle-clues leading to some culmination like the original story idea for KSP, or even something more scripted to fit an actual 'campaign'
- Factions to work with/compete against
- Some kind of multiplayer support
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I for one look forward with cautious optimism to the future. There are companies who specifically purchase IP in order to ruin it, but that exclusively happens when that IP is in competition with something else the acquiring company offers. That's definitely not the case with KSP. It's possible that Take 2 will somehow flub the KSP market, but I don't think they'll set out to do so.
Big companies aren't evil by virtue of being either big or companies. They sometimes make decisions you might disagree with, because they prize different things (revenue, for example), but it's not like Take 2 is staffed by a secret cabal of sith wizards who extract continual youth from the tears of gamers. And the funny thing about caring about revenue for a product is that Pareto optimization is automatically psuedo-democratic.
Maybe with fresh collaboration efforts, someone will finally have the bravery to fix some of the established warts in KSP, like the career system. Probably not, but a man can dream.
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...you know what, sure, I'll give this a go.
Though don't be surprised if I just drop off the radar. I've got an RP-0 save that needs my attention, and, you know, real life keeps interrupting.
Important mods:
- [x] Science!
- BetterBurnTime
- Docking Port Aligment Indicator
- Interstellar Fuel Switch. This might get moved to ModularFuelTanks. I have this because I want to be able to use the NERVA, eventually.
- Kerbal Engineer. I'm aware this makes things way, way easier.
- Kerbal Inventory System. I never use this, and maybe this save will force me to finally do something with it.
- PreciseNode - I might drop this.
- Procedural Fairings
- TAC Life Support
- Universal Storage - I've never used this before, and it looks interesting.
I also have a number of other QoL/visual mods, but nothing that should change gameplay.
This will also be one of the very few times I play the game without Kerbal Construction Time. We'll see how that works out; maybe KCT has been holding me back and contributing to my KSP fatigue.
Settings screenshots:
Spoiler
Hopefully I'll get a chance to fly later today or tomorrow.
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You beat me to this post by about ten seconds.
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Thanks. I was hoping for some specific link hinting for a resolution to the problem; I know where to find Heat Pumps. I'll look about and see if I find something.
(I'm not upset or snarking at you; just explaining that I didn't intend to use you as my personal LMGTFY)
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1 hour ago, hypervelocity said:
Nuclear/Hydrolox with the boiloff fixes suggested before & in the HeatPump threads
You happen to have a link? Last I checked the HeatPump thread (yesterday morning) there was still a problem with timewarp over 1000x, which for me personally isn't worth the trouble.
I suppose I could just bash together an MM cfg to remove all boiloff from cryogenic tanks.
Also, thanks guys for answering my question above.
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I'm one of those masochistic guys who likes to build planes in RSS/RO and try to get them to space, not because it's a good idea, but because I want to, damnit.
I was surprised to find in 1.2.2 that the runway now has huge gaps that like to catch my gear and toss my plane into the air. I vaguely remember some blog post about Squad trying to fix something with PQS modeling, so I suspect this is a stock bug that just gets hugely magnified by the real scale, but I figured I'd ask: does anyone know a fix, patch, or workaround for this issue?
T'anks.
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Saw on the last page that the tutorial (and the whole project) is being reworked, which is really cool. However, I've never used CactEye before; does any one of you end-users have a quick-and-dirty run-down of how it works? I've just realized in my save I have no idea what I'm doing.
I searched for CactEye tutorials, but what I've seen so far is from 2014 and doesn't appear to have much to do with what I see in my game. (That said, the telescope I'm using is in Solar orbit, and I saw an off-hand comment that the telescopes only work in high Kerbin orbit?)
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Hi all,
I've recently discovered I'm not as clear on how to launch into a specific orbit as I thought I was.
I'm talking about in the simplified case provided by Kerbin; you launch from the equator into an orbit with Kerbin at the centre. I'm not concerned with off-equatorial launches, not orbits around bodies not the launch body.
What I thought would have worked would be: time warp until the longitude of your ascending node is (roughly) the same as the LAN of the target orbit. Then, offset your launch angle from the East according to the inclination of the target orbit - so if the inclination you want is 20 degrees, you launch at 90-20=70 degrees on the navball.
Unfortunately this didn't work. My orbit ended up in a vastly different orientation, though the same inclination.
What did I do wrong?
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13 minutes ago, tater said:
Any tunnel has to hold water out, so that's a standard tunneling issue.
True, to a point. There's a difference between 'the ground is leaky' and 'we want to tunnel underwater' as a matter of engineering.
I'm not claiming this makes it unfeasible, just that it's maybe a reason to consider it uneconomic.
If that's even the case. It's a question.
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Someone else who knows better than me: isn't LA only just above its own water-table? Wouldn't boring holes underneath it require you to constantly evacuate said water?
Not that this is impossible (see: Chunnel), just maybe not an awesome idea (see: Chunnel). -
So, OK, it's clearly impossible with real materials.
But what about whatever-it-is that Kerbal planets are made of?
And, for those who don't want to do the integral proving that the outer shell imparts no gravity on anything inside it, you can get halfway there by thinking about it in terms of subtending angles. Choose some spot to look out from the inner body, and some angle of deviation for your gaze (say, 10 degrees). Then, when the inner body is in the centre, the cone of your gaze will cover (subtend) a certain amount of the outer shell. Now move the inner body further away, by having it drift in the opposite direction of your gaze. Then, the outer shell on that side will be further away, and therefore impart less gravitational force - but the same angular cone will subtend more of it, meaning that more of it will pull along that cone. It so happens that the amount of less pull because of distance and amount of more pull because of greater subtension exactly cancel one another.Also, for those who have done undergrad E&M: gravitational potential works exactly the same way as electric field potential, so you've already done this proof.
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47 minutes ago, regex said:
Adding some Jool lagrange asteroids and some randos out past Eeloo would definitely offer a few new options for players, although I have no idea why Squad thought adding asteroids to orbit Dres would be a particularly good thing...
Camouflage.
Can't hate on Dres if you can't find it.
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Scientist? At least, when I get a chance to play KSP at all anymore, instead of writing code.
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...okay, I'll assume silence is consent, unless I hear otherwise!
Some time soon I'll either update my version of the license, to include credit where I realize credit is due, or take my stuff off GitHub. Probably the former.
Thanks for all your help, guys!
Any way to change RCS noises?
in KSP1 Discussion
Posted
I just ran my first SSTO spaceplane in a few years yesterday, and I was unpleasantly surprised by the 'new' RCS noises firing constantly in my ears. Does anyone know of a way to disable or change those noises either within the game or with a mod?
I can probably fairly easily track down the relevant audio files and replace them with blanks, or more reasonably use MM to remove their audio effect configurations, but it's always nice if someone else has already done the work for you.