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Thread: Some Apollo-Orion graphics that might be useful

  1. #61
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    Quote Originally Posted by grant hutchison View Post
    I thought I told you guys to just play quietly and keep the house tidy while I was out? Sheesh.


    Yes, everyone but TimFinch understood correctly that the Apollo transfer orbit goes nowhere near the poles. The first two images make that pretty clear, I thought.

    For reference, here's another image with my lunar orbit marked in blue, showing that (as people have pointed out) the transfer orbit is not in the same plane as the lunar orbit.
    Attachment 23261

    My model doesn't include a plane change at TLI. I wanted to cut things down to the bare minimum that showed the important detail - so EPO is a circular orbit corresponding to a direct eastward launch from the Cape, the Apollo transfer orbit is in the same plane as EPO, as is the Orion orbit, and the Moon is sitting in the ecliptic plane to make the sums easier. I also haven't included the perigee lowering that was carried out for ETF1, which actually had a perigee within the Earth during its second orbit, to test high-speed re-entry.
    With a bit of work I could add these details, but I think they would complicate things without improving the explanatory power - In contrast to the usual use of Celestia I'm just trying to draw a good diagram, rather than create a realistic depiction.

    Grant Hutchison
    And IMHO you did a damn fine job. Well done.

    I simply cannot fathom why anyone cannot understand the clear illustrations.

  2. #62
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    He will no doubt say that didn't happen or prove that it happened, by NASA, that way, but good illustration again, thanks.

  3. #63
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    What? Not enough love to spread around for my enhancement in post 14?

  4. #64
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    Quote Originally Posted by DaveC426913 View Post
    What? Not enough love to spread around for my enhancement in post 14?
    That was another good representation of the 3-D model displayed in 2-D, good job Dave.

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    Given in post 59, Dave. 😄

    It's an excellent addition to show three dimensionality of the situation.

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    Quote Originally Posted by DaveC426913 View Post
    What? Not enough love to spread around for my enhancement in post 14?
    I thought it was a great way to clearly show just how off-base Tim was with his claim about the TLI going over the poles. Instead of acknowledging it, he went on the offensive with his nonsense about his question was intended for Grant and should only be answered by Grant. Pretty typical of him to attempt to divert attention away and prolong the discussion along some other tangent that he thinks nobody will notice.

  7. #67
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    Quote Originally Posted by AGN Fuel View Post
    Given in post 59, Dave. ��

    It's an excellent addition to show three dimensionality of the situation.
    Didn't even see that. :egg on face:

  8. #68
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    Quote Originally Posted by DaveC426913 View Post
    What? Not enough love to spread around for my enhancement in post 14?
    Sorry. Your effort was actually damn fine too. However, unfortunately, the squeaky wheel and all that jazz.

  9. #69
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    Quote Originally Posted by bknight View Post
    A drawing with of TLI plane would be great since I don't know the capability of Cellesta, is this possible to plot in say a different color on you first image?
    I can do that, if I trick Celestia a little.
    The difference isn't going to be particularly impressive, though, unless I misunderstand Apollo By The Numbers. If you take Apollo 11, the TLI burn was carried out at a fixed flight path angle of 7.367 degrees, but that resulted in a plane change of only about a degree, from the EPO inclination of 32.521 degrees to the LTO inclination of 31.386 degrees. (there's disagreement between sources in the third decimal place for this figure). Notice that the TLI actually reduces the inclination in this case, nudging Apollo slightly towards the VAB. My toy depiction uses an even lower inclination, however - just the latitude of the Cape - so errs on the side of danger rather than caution.
    What would make a much more obvious difference would be if I used the real eccentricity of the LTO - Apollo was well over-velocity for a Hohmann transfer, and in the absence of the moon would have ended up a great deal farther out than lunar orbital distance. I decided not to do that in my depiction because it would (in the setting of TimFinch's thread) generate more heat than light. Probably worth doing now, though.

    Grant Hutchison
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  10. #70
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    Quote Originally Posted by Abaddon View Post
    Sorry. Your effort was actually damn fine too. However, unfortunately, the squeaky wheel and all that jazz.
    Wait. Are you saying I'm the squeaky wheel?

    Grant Hutchison
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  11. #71
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    Quote Originally Posted by grant hutchison View Post
    (there's disagreement between sources in the third decimal place for this figure)
    Thus proving the moon landings are fake.
    At night the stars put on a show for free (Carole King)

    All moderation in purple - The rules

  12. #72
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    Quote Originally Posted by selden View Post
    Grant,

    Would you mind posting the SSCs that you used for the trajectories?
    In case anyone's fretting about this, I emailed selden the necessary file.

    Grant Hutchison
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  13. #73
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    Quote Originally Posted by grant hutchison View Post
    I can do that, if I trick Celestia a little.
    The difference isn't going to be particularly impressive, though, unless I misunderstand Apollo By The Numbers. If you take Apollo 11, the TLI burn was carried out at a fixed flight path angle of 7.367 degrees, but that resulted in a plane change of only about a degree, from the EPO inclination of 32.521 degrees to the LTO inclination of 31.386 degrees. (there's disagreement between sources in the third decimal place for this figure). Notice that the TLI actually reduces the inclination in this case, nudging Apollo slightly towards the VAB. My toy depiction uses an even lower inclination, however - just the latitude of the Cape - so errs on the side of danger rather than caution.
    What would make a much more obvious difference would be if I used the real eccentricity of the LTO - Apollo was well over-velocity for a Hohmann transfer, and in the absence of the moon would have ended up a great deal farther out than lunar orbital distance. I decided not to do that in my depiction because it would (in the setting of TimFinch's thread) generate more heat than light. Probably worth doing now, though.

    Grant Hutchison
    Ok, your depiction of A17 was good and showed similar angular difference. I wasn't aware that the plane change angle was only a degree, I though it was like 10 degrees. Bob B. and I worked on a TLI simulator a couple of years ago. I just looked at it and the TLI end vector was 7.453 (11.3 horz. 10.2 vert. m/s^2) My memory was wrong and you are about right on. Oh well learn something new every day.
    Last edited by bknight; 2018-Apr-29 at 01:19 AM. Reason: Added ^2

  14. #74
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    Quote Originally Posted by Swift View Post
    Thus proving the moon landings are fake.

    But of course.

  15. #75
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    Quote Originally Posted by grant hutchison View Post
    Wait. Are you saying I'm the squeaky wheel?

    Grant Hutchison
    Hahaha. No.

  16. #76
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    Quote Originally Posted by grant hutchison View Post
    Wait. Are you saying I'm the squeaky wheel?

    Grant Hutchison
    Quote Originally Posted by Abaddon View Post
    Hahaha. No.
    Perhaps I should be more verbose. I already posted how great your renderings were. That goes without saying. And I am familiar with how fantastic Celestia is. A friend of mine develops various skins for planets based on data as it arrives from the various probes out there as a hobby. I never got into that, but we used to discuss the finer points of the geometry. But none of that is really important. Now you have single handedly re-invigorated my interest in Cellestia, so everyone is a winner. Well almost everyone. The dearly departed don't get to comment.

  17. #77
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    OK, now I have downloaded it and installed it vanilla. After a brief interlude of relearning the controls, I admit I had forgotten how totally awesome it really is. Grant, you have now officially wrecked my weekend. I will not sleep.

  18. #78
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    Quote Originally Posted by Swift View Post
    Thus proving the moon landings are fake.
    Well then...DIRECT QUESTION for Swift!

  19. #79
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    Quote Originally Posted by mako88sb View Post
    I thought it was a great way to clearly show just how off-base Tim was with his claim about the TLI going over the poles. Instead of acknowledging it, he went on the offensive with his nonsense about his question was intended for Grant and should only be answered by Grant. Pretty typical of him to attempt to divert attention away and prolong the discussion along some other tangent that he thinks nobody will notice.
    As I've demonstrated before, it's not a matter of ignorance but ignoring.

  20. #80
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    Quote Originally Posted by DaveC426913 View Post
    What? Not enough love to spread around for my enhancement in post 14?
    Doh!

    Take a look at Post 27. That was intended for you DaveC426913, but I hit the reply to nomuse's reply instead. I have saved your diagram to my hard drive too. I really like the projection.
    Last edited by Baron Greenback; 2018-Apr-29 at 08:27 AM.

  21. #81
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    Quote Originally Posted by Abaddon View Post
    Perhaps I should be more verbose. I already posted how great your renderings were.
    Yeah, I know, thanks. I was just teasing.

    Grant Hutchison
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  22. #82
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    Quote Originally Posted by bknight View Post
    Ok, your depiction of A17 was good and showed similar angular difference. I wasn't aware that the plane change angle was only a degree, I though it was like 10 degrees. Bob B. and I worked on a TLI simulator a couple of years ago. I just looked at it and the TLI end vector was 7.453 (11.3 horz. 10.2 vert. m/s^2) My memory was wrong and you are about right on. Oh well learn something new every day.
    OK, glad that makes sense for you.
    There's potentially a lot that can be done with this in Celestia. The Apollo By The Numbers data are sufficient to produce a set of Celestia orbital elements for the real Apollo departure trajectories - just a bit of spherical trig and a couple of coordinate transformations, by the look of it. Back in the day, when we were developing Celestia, it's the sort of thing I'd have knocked off in a couple of hours one evening, but nowadays I'd need to reacquaint myself with some of Celestia's more eccentric coordinate choices. And with a set of osculating elements for the moon's orbit at the epoch of each TLI (easily obtained from JPL Horizons, but another interface to relearn), it would be easy enough to trick Celestia into drawing the plane of the Moon's orbit on the surface of the Earth.

    Grant Hutchison
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  23. #83
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    For anyone interested, here are the relevant data for TLI plane change taken from Apollo By The Numbers:
    Click image for larger version. 

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    Bob Braeunig used 31.383 degrees for the inclination of the Apollo 11 departure trajectory when he did his radiation dose calculations. That figure appears here. (Which is one of end tables of Apollo By The Numbers - there are some very small differences between the chapter tables and the end tables.)

    Grant Hutchison
    Last edited by grant hutchison; 2018-Apr-29 at 06:15 PM. Reason: bracketed
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  24. #84
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    Looking through the tables in Apollo By The Numbers, none of the plane changes at TLI were particularly large, and almost all involved a slight decrease in orbital inclination. The largest plane change (and the only one over 2 degrees) was Apollo 12, from 32.540 degrees to 30.360 degrees. The only increase in inclination from a TLI was by 0.017 degrees, Apollo 15.

    So plane change doesn't seem to have had a role in reducing VAB immersion for Apollo - if anything, slightly the opposite.

    Grant Hutchison
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    During life, we all develop attitudes and strategies to make our interactions with others more pleasant and useful. If I mention mine here, those comments can apply only to myself, my experiences and my situation. Such remarks cannot and should not be construed as dismissing, denigrating, devaluing or criticizing any different attitudes and strategies that other people have evolved as a result of their different situation and different experiences.

  25. #85
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    Quote Originally Posted by grant hutchison View Post
    Looking through the tables in Apollo By The Numbers, none of the plane changes at TLI were particularly large, and almost all involved a slight decrease in orbital inclination. The largest plane change (and the only one over 2 degrees) was Apollo 12, from 32.540 degrees to 30.360 degrees. The only increase in inclination from a TLI was by 0.017 degrees, Apollo 15.

    So plane change doesn't seem to have had a role in reducing VAB immersion for Apollo - if anything, slightly the opposite.

    Grant Hutchison
    I can only think that the flight path angle was downwards. Rather than increase the inclination for whatever miniscule reduction in exposure it would give, possibly the need for a tighter trajectory was more important.

  26. #86
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    Quote Originally Posted by Clanger View Post
    I can only think that the flight path angle was downwards. Rather than increase the inclination for whatever miniscule reduction in exposure it would give, possibly the need for a tighter trajectory was more important.
    I believe it was upwards. If you look at the table in Braeunig's calculation of the Apollo 11 departure trajectory, you'll see that the flight path angle increases steadily (and initially dramatically) long after the TLI burn is completed - 40 hours or so into the LTO. So it's something that happens to ballistic trajectories as well as powered trajectories. And if the flight path angle in Braeunig's table represented a downward deviation, the Earth would have soon got in the way!
    What we're seeing is the angle between the flight path and "local horizontal" - that is, the plane at right angles to the radius vector of the orbit. If you sketch a very eccentric ellipse (near as dammit a parabola), you'll see how the flight path angle pitches up during the initial departure phase from perigee.

    And if you look at datasets describing TLI, you'll see they give us two angles that give a complete description of the trajectory in space - the flight path angle (above or below the local horizontal) is complemented by the heading angle, which is the angle measured within the local horizontal plane, clockwise from north.

    Grant Hutchison
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    During life, we all develop attitudes and strategies to make our interactions with others more pleasant and useful. If I mention mine here, those comments can apply only to myself, my experiences and my situation. Such remarks cannot and should not be construed as dismissing, denigrating, devaluing or criticizing any different attitudes and strategies that other people have evolved as a result of their different situation and different experiences.

  27. #87
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    Yes the number that I have at ~40 hr. is 78.769 just a degree larger than Bob. with 1258.3 m/s vs. ALFJ of 1194 m/s, but it is a simple spreadsheet simulator. Bob was very good with it. And there was no Lunar reaction in mine.
    Last edited by bknight; 2018-Apr-29 at 10:42 PM. Reason: Add Lunar reaction

  28. #88
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    Quote Originally Posted by Baron Greenback View Post
    Doh!

    Take a look at Post 27. That was intended for you DaveC426913, but I hit the reply to nomuse's reply instead. I have saved your diagram to my hard drive too. I really like the projection.
    Ah. I wondered about that.

  29. #89
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    So the Horizons web interface turned out to be easier to learn than the old email system I used previously.

    The moon's orbit evolves pretty quickly, so it changed significantly during the 1968-1972 Apollo period. Here are the lunar orbits from osculating elements for the TLI dates for all nine lunar Apollo missions:
    Click image for larger version. 

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    (You'll see all my various versions of the moon are scattered pretty widely by the current epoch - that just reflects how quickly osculating elements for the moon become unusable. I've checked against ephemeris that the position of the moon is correct at each corresponding TLI epoch.)

    If we draw all those planes on the surface of the Earth we get this:
    Click image for larger version. 

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    A generic EPO and Pacific TLI are included for reference, but I removed the magnetic field for clarity.

    Grant Hutchison
    Last edited by grant hutchison; 2018-Apr-29 at 11:34 PM.
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  30. #90
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    Well, it would have been faster if I hadn't got hung up on extracting the true anomaly from the eccentricity and the flight path angle. I was sure that was enough information on its own, but I ended up with a horrible equation that I had to solve numerically.

    So I came at it a different way from Braeunig, and avoided looking at his page until I'd produced the elements myself in my own way ... and they're pretty much identical, to the extent that when I plot Braeunig's Apollo 11 alongside my own, the two aren't really visually separate until 3 days into the mission, at the time of Lunar Orbit Insertion. They are, of course, simple two-body ellipses with no modification from lunar gravity, but they're certainly in the right vicinity at the right time.
    Click image for larger version. 

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    Back at the Earth's surface, I created a marker named "Antipode +3", which marks the antipodal point of the Moon three days in advance - that is, it's directly opposite the location the moon is going to be in when Apollo 11 gets there. TLI should take place in this vicinity. Here are the locations at the start of TLI:
    Click image for larger version. 

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    And at the end:
    Click image for larger version. 

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    So the simulated Apollo burns right across the antipode, as it should.

    The only outstanding puzzle is that the end of TLI isn't quite at the correct geographical coordinates. This seems to be a problem with the conversion of Apollo's geographical coordinates to J2000 equatorial coordinates. It seems too big an effect for just 30 years of precession, but I'll poke around and see if I can discover what's causing it.

    Grant Hutchison
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    During life, we all develop attitudes and strategies to make our interactions with others more pleasant and useful. If I mention mine here, those comments can apply only to myself, my experiences and my situation. Such remarks cannot and should not be construed as dismissing, denigrating, devaluing or criticizing any different attitudes and strategies that other people have evolved as a result of their different situation and different experiences.

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