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Post by sts60 on May 23, 2008 10:52:50 GMT -4
From the Apollo 11 Mission Report: "The digital autopilot was used to initiate the passive thermal control mode at a positive roll rate of 0.3 deg/sec, with the positive longitudinal axis of the spacecraft pointed toward the ecliptic north pole during translunar coast." Thus the CSM/LM stack was broadside to the sun, and parallel to the Earth's terminator. This is consistent with the image from the television broadcast: <image> A cursory look at the Apollo 11 Flight Plan shows the stack being in PTC at the time of the PAO event, but I didn't really see any details. My question for Count/Jay/Bob/whoever - didn't the video downlink use the S-band antenna on the SM? If so, wouldn't that require a different attitude, or at least a cessation of PTC roll?
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Post by Halcyon Dayz, FCD on May 23, 2008 11:47:55 GMT -4
Doesn't stuff like that get covered in high school?
I mean, it's very basic physics.
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Post by dinsmore on May 23, 2008 12:14:34 GMT -4
Not In England, because it's hard and pupils might fail the exam, and then the school would drop down the league table and the head would get sacked. So they do music instead, and even the exam papers for this have the answers on the back. news.bbc.co.uk/1/hi/education/7414129.stm
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Post by JayUtah on May 23, 2008 12:26:14 GMT -4
My question for Count/Jay/Bob/whoever - didn't the video downlink use the S-band antenna on the SM? If so, wouldn't that require a different attitude, or at least a cessation of PTC roll?
I believe the high-gain antenna on the SM was used, and that typically does require stopping the PTC roll but not changing the orientation of the spacecraft's long axis.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on May 23, 2008 13:24:20 GMT -4
Doesn't stuff like that get covered in high school? I mean, it's very basic physics. I suppose it depends on what level of math one has taken. I'm pretty sure I studied vectors in high school, but then again, I loaded up on all the advanced math and science courses. It's too long ago for me to remember exactly what I studied and when. It could be that the basic courses taken by most students don't get that far.
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Post by LunarOrbit on May 23, 2008 17:11:13 GMT -4
Anyone who has watched Babylon 5 got a pretty good lesson on how spacecraft move in space. I loved how their Star Fury fighters could spin around and shoot an enemy behind them (or anywhere else) without changing the direction they were traveling in.
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raven
Jupiter
That ain't Earth, kiddies.
Posts: 509
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Post by raven on May 23, 2008 18:03:02 GMT -4
Like Asteroids! The ol' timey video game Asteroids is like 2D space travel, with infinite fuel and no gravity issues. In my computer chair general musings on space travel, it is my opinion that the best shape for an outer space warship would be long and needle like, allowing the most maneuverability to spin on its orientation away from weapons, without having to make a fuel guzzling mid course correction.
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Jason
Pluto
May all your hits be crits
Posts: 5,579
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Post by Jason on May 23, 2008 18:10:51 GMT -4
The Vipers in the new Battlestar Galactica do the same thing as the B5 fighters, and they have little attitude thrusters on the nose and sides that fire when they maneuver. The opening episode of the season had a Cylon raider turn to face a viper following it while still traveling backwards.
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Post by LunarOrbit on May 23, 2008 19:59:04 GMT -4
I regret not using my favourite TV show (Battlestar Galactica) as an example. I'm ashamed of myself. I wonder if Turbonium believes the Apollo spacecraft had to fire it's rocket for the entire trip between the Earth and Moon? Why else would it be necessary to point the nose at a specific point?
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Post by LunarOrbit on May 23, 2008 20:03:26 GMT -4
Exactly. Fun game, and educational too! I'm glad I'm not the only one who thinks about stuff like that. ;D I think your design would be fine as long as there was artificial gravity and inertial dampers. Anyone standing at the nose or tail during a sudden yaw or pitch maneuver might get tossed around.
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Post by Kiwi on May 24, 2008 8:14:37 GMT -4
At this time, the astronauts would not have had a view of the Earth through the hatch window, which was in the CSM's nose cone! This is unclear. By nose cone, do you mean the hatch window was at the very front of the Command Module in the hatch that was opened to allow access to the docked Lunar Module?
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Post by Kiwi on May 24, 2008 8:55:49 GMT -4
Yup. If you actually calculate the angular diameters of Earth and the window you find that at about 130,000 miles distance from Earth they'd have to get over 12 feet away before the angular diameter of a 9" diameter window got smaller than the angular diameter of the Earth. They don't have 12 feet to move away from the window inside the command module, so they could film the entire Earth through that window at any distance from the window that they could be. Jason, I realise you are challenging Turbonium to work this out for himself, which would be a good thing for him to do instead of merely guessing, but perhaps he's not capable, otherwise he would have done so before he posted. If you were to show the maths, or even an illustration, the figures would at least be available for him to check.
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raven
Jupiter
That ain't Earth, kiddies.
Posts: 509
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Post by raven on May 24, 2008 9:40:53 GMT -4
I'm glad I'm not the only one who thinks about stuff like that. ;D I think your design would be fine as long as there was artificial gravity and inertial dampers. Anyone standing at the nose or tail during a sudden yaw or pitch maneuver might get tossed around. Hmmm, are we talking bone crushing, human jam-type g forces, or could it be doable with some gyroscopic acceleration coaches, or at least extra padding on the bulkheads? Probably it would be worse the closer you got to the nose and tail.
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Post by nomuse on May 24, 2008 13:05:26 GMT -4
To add to the Asteroids musings, its progenitor was a little game called Space War. Similar graphics, but in Space War there was a central sun. If you played it solo you could set up an orbit, circularize it, drop to higher or lower orbits, etc. A few minutes of play did more for an intuition of how orbits work then hours of re-reading the same paragraph in a textbook and trying to understand it.
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raven
Jupiter
That ain't Earth, kiddies.
Posts: 509
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Post by raven on May 24, 2008 13:36:52 GMT -4
I have heard of Space Wars, even played it on a Java version. It was one, if not the oldest computer game, older even then Pong. Quite challenging.
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