Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Nov 23, 2009 12:35:04 GMT -4
Hi Just joined after finding this site a few days ago While i've never doubted Man has walked on the Moon, this thread and in particular Bob B's work has been not only educational (I never realy thought about the Van Allen Belt) but quite fun as well (i got the idea after the Doughnut) Any way great site and a great bunch of people, i hope i can contribute in the future ( if you ever need to know the correct way to make a martini to help debunk a HB then I'll be there) Hi, gee. Welcome to the forum. Education, both of myself and others, is why I do this stuff. I love learning new things, and this was a great opportunity to fully comprehend the Apollo trajectories as opposed to just having a general notion of how it was done. Whether fm appreciates it or not, I don't care, because it wasn't done for fm. And you're right about Jay's doughnut demonstration, he had the geometry pretty much spot on.
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Post by gwiz on Nov 23, 2009 13:13:34 GMT -4
Was this outward path at a southerly latitude an exception? Yes, unique to Apollo 17 which flew an extra half-rev in low orbit prior to TLI. I've yet to see a detailed explanation why, beyond a passing comment that it was connected with the high lunar latitude of the landing site.
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Post by Mr Gorsky on Nov 23, 2009 13:56:00 GMT -4
I just wanted to say a quick thinks to everyone who has contributed knowledge and experience to this thread ... I can honestly say that I know much more about the VABs and how Apollo navigated them than I did before.
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Post by drewid on Nov 23, 2009 14:54:35 GMT -4
Was this outward path at a southerly latitude an exception? Yes, unique to Apollo 17 which flew an extra half-rev in low orbit prior to TLI. I've yet to see a detailed explanation why, beyond a passing comment that it was connected with the high lunar latitude of the landing site. I remember reading that 17 was the only mission to go out on a totally non-free-return orbit. They were obviously getting pretty confident by then
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Nov 23, 2009 15:48:13 GMT -4
I remember reading that 17 was the only mission to go out on a totally non-free-return orbit. They were obviously getting pretty confident by then They definitely took more chances as the confidence grew. Going from memory, I'm pretty sure Apollo 8, 10 & 11 were all free-return trajectories. I don't know about Apollo 12. Apollo 13 was a hybrid trajectory, that is, it started out as a free-return but then deviated from it after a mid-course maneuver. (After the O2 tank explosion, they had to use the LM DPS to get back on free-return.) If Apollo 17 was the only totally non-free-return, then I'm guessing Apollo 14, 15 & 16 were probably also hybrid trajectories.
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Post by JayUtah on Nov 23, 2009 16:09:51 GMT -4
Apollo 12 used a hybrid trajectory. Hybrid trajectories are free-return up until a certain MCC point, at which point they are "corrected" to their mission trajectory.
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Post by JayUtah on Nov 23, 2009 16:40:23 GMT -4
Well like I said, I couldnt imagine the trip to and fro being the same Nice try. You were suggesting that the return trajectory was straight back to Earth -- i.e., close to a straight line and therefore straight through the most intense parts of the Van Allen belts. The return trip is still an orbit defined by the basic translunar trajectory elements, but inclined slightly differently from the departure orbit. You still haven't figured out how inclination affects your claims. You're still puttering around with distance or geodetic altitude alone, with no understanding of three dimensions.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Nov 23, 2009 16:54:07 GMT -4
AS17-148-22727 was taken on Apollo 17's outward journey from a little below an extension of the Tropic of Capricorn, and I wonder if it is useful to illustrate the path taken to avoid the most intense parts of the VABs. It shows the earth from Antarctica up to the Middle East. That's a great picture, and I agree it would help illustrate the point, but do you know of any similar photos from missions other than Apollo 17? I'd prefer not use an Apollo 17 photo because, although the principles were the same, it was backward from the other missions (leaving to the south and returning from the north).
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Post by rob260259 on Nov 23, 2009 17:58:07 GMT -4
How much more do you need FM? You even got answers on questions that you couldn't think of. What about the question JayUtah asked about the wavelength of Bremsstrahlung produced in aluminum and how far it penetrates aluminum for common shielding thicknesses?
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Post by petereldergill on Nov 27, 2009 1:43:23 GMT -4
Bob...I haven't posted on here in a couple of years (but have never really left) I showed your translunar orbit to my grade 12 Physics class. I've just finished teaching them *basic* orbital mechanics and then showed them your calculations and your webpage. Thanks. They really enjoyed the animation. Losing speed while gaining separation is the basics of what we learn. I don't understand a fraction of what you did, and made that fact very clear to them. What I wanted them to get out of it was an appreciation of the detail that needs to go into determining orbits. Heh..scrolling down your page, I said stuff like.."That's a complicated graph....here's another complicated graph.." and so forth I'm so glad you showed us this. I even told them that "Bob *forgets* more about orbital mechanics every year than our entire class together (including me) knows about orbital mechanics" Tee hee Thanks, Bob If there's any other resources for a highschool level that you might find appropriate and can send my way, let me know! My email is pelderg at hotmail Thanks so, sp much! Pete
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Nov 27, 2009 16:51:18 GMT -4
You're welcome. I'm glad to hear my work had a useful purpose.
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Post by drewid on Nov 29, 2009 19:17:08 GMT -4
Finally got round to uploading this. I've uploaded it on my crapsponge account. Even so I've disabled comments because I can't be bothered dealing with the idiots.
Can be seen in higher res on youtube itself:
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Post by drewid on Dec 7, 2009 17:54:25 GMT -4
And another one.
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Post by Apollo Gnomon on Dec 7, 2009 18:13:15 GMT -4
Nice work!
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Post by Count Zero on Dec 7, 2009 21:40:38 GMT -4
That is absolutely brilliant! I like how you can see the "window" start to close as the thicker part of the belt rotates into the plane of the trajectory.
That, sir, is definitive.
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