raptop changed the topic of #principia to: READ THE FAQ: http://goo.gl/gMZF9H; The current version is Galileo. We currently target 1.5.1, 1.6.1, 1.7.x, 1.8.1, and 1.9.1. <scott_manley> anyone that doubts the wisdom of retrograde bop needs to get the hell out | https://xkcd.com/323/ | <egg> calculating the influence of lamont on Pluto is a bit silly… | <egg> also 4e16 m * 2^-52 is uncomfortably large
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RurouniDonut. — I heard KSPTOT is somewhat decent with Principia
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Stonesmile. — Pretty sure this is just due to rotation of the focus body
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Butcher. — How fast is Neptune rotating?
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Stonesmile. — ~16h
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Butcher. — It's telling me I'm moving at *1.7c* relative to the surface.
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Stonesmile. — ~16h/rotation (edited)
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Standecco. — that's _definitely_ not the case
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Butcher. — The ECEF one is because that's not Earth, it's one of the Moon's with an E as the first letter. 😉
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Butcher. — The ECEF one is because that's not Earth, it's one of the Moons with an E as the first letter. 😉 (edited)
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Standecco. — the only thing that could come close to these relative speeds would be 2 points on the surface of 2 neutron stars rotating in opposite direction
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Standecco. — that would ignore relativity, of course, but the point is that there's no way that this is not a bug
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Butcher. — Maximum speeds in the solar system should be under 100 km/s even relative to the surface of other bodies.
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Stonesmile. — Would it be fair to assume that your vessel is not moving relative to the sun from neptunes view?
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Standecco. — your velocity relative to the sun should be the same in any inertial frame of reference
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Standecco. — the surface of a rotating body isn't an inertial frame of reference, but the error probably won't be that large
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Butcher. — That's my speed relative to Neptune.
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Butcher. — Which is about what I'd expect.
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Stonesmile. — You 'orbit' neptune once every 16h, at the height of about 29 to 31 AU, that gives those numbers
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Butcher. — Hmm, I suppose if you treat it as orbital velocity at that height you'd get something like that.
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Standecco. — orbital velocity at that height would be 0, not c
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Butcher. — With a 16h period it would be very large.
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Butcher. — A 30 AU radius gives a circumference close to 100 AU which is traversed in 16 hours.
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Standecco. — and it's still not correct; you'd see those kinds of speeds only if he were stationary in regards to the surface of neptune at 30 AU (so a velocity of 2π30AU/16h), but that'd be relative to the sun
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Stonesmile. — If you flip it around, it would mean neptune would have a year of 16h at the same distance - that would be fast
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Stonesmile. — If someone has a GEO sat, that would probably show close to 0 in ECEF
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Butcher. — It does, yes.
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Standecco. — if you were to take the velocity relative to a point that is 30 AU from the surface of neptune and stationary in regards to it, then you'd see those numbers
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Stonesmile. — SO the math holds, it's just the usage of 'wrong' refrence frame that shows those numbers
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Stonesmile. — So the math holds, it's just the usage of 'wrong' refrence frame that shows those numbers (edited)
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Standecco. — it's not considering you orbiting around neptune at 30 AU, that would give very low numbers + the angular speed * surface radius
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Standecco. — rather, it's somehow extending neptune's surface, or something similar
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Butcher. — Using the fixed frames when you're not in orbit of that body is pretty dubious true.
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Standecco. — I'd assume that's the vertical motion induced by the moon
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Butcher. — Yes, it also has a bit of longitude drift from when I last corrected its inclination.
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Standecco. — how far is your rover from neptune, exactly?
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Standecco. — alright, assuming 30 AU, the numbers more or less match
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Standecco. — that is your velocity relative to the surface of neptune, _if neptune had a 30 AU radius_
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Standecco. — but still a 16h period
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Stonesmile. — So you think the math for xCxF should be changed?
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Standecco. — possibly; if I could make any sense out of principia's code, I could check how it's calculated
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Stonesmile. — The easy way would be to ask 🥚
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Standecco. — well if the error really is there, he'll know how to fix it for sure
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egg. — Not sure why you think there is something wrong with those numbers
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egg. — @Standecco there is no error
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Standecco. — speed relative to the surface of neptune is supposed to be 1.7 c ?
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Standecco. — if so, I definitely misunderstood what surface fixed frames are
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Butcher. — It's speed in a frame of reference that holds neptune's surface stationary.
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egg. — the reference frames are rigid
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Butcher. — As such you're effectively doing whatever Neptune's angular velocity is at whatever distance you're at, which gives some fairly huge numbers.
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egg. — indeed
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Butcher. — So it's as though you're doing a 30AU revolution every 16 hours, hence 1.7c (since that's how fast you would need to be travelling to do that).
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Standecco. — so if you had that speed, the surface fixed reading would show 0?
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Butcher. — Yes.
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Standecco. — and indeed, math works out right, as always
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Stonesmile. — Pretty sure this is a TUfX issue, I have noticed the lines get more vibrant with TUfX, so with a certain config it could break
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Standecco. — DoF?
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EpicGunMachine. — @Falcon hit the default one then go back to your one
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EpicGunMachine. — it should fix it
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Falcon. — yeah i used zorgs configs and it fixed it