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Author Topic: Did Noonan use William's flight plan?  (Read 22575 times)

Tom Swearengen

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Re: Did Noonan use William's flight plan?
« Reply #15 on: February 20, 2012, 06:05:03 PM »

Harry---you got me on that one---but I think we can agree that Albert was a one of a kind.
Tom Swearengen TIGHAR # 3297
 
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Gary LaPook

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Re: Did Noonan use William's flight plan?
« Reply #16 on: February 20, 2012, 06:20:26 PM »

And it happens that while we could 'chuckle' at the Lae-Howland segment, that part just HAPPENS to lie close to the equator - the whole world route DID NOT; and the Lae-Howland segment was JUST THAT - A SEGMENT.  Why would he do any less than his best at any part of the whole thing?


Yes the whole route did lie close enough to the equator that there was only a negligible advantage to using the great circle instead of the rhumb line. I have all of Williams' strip chart. The only ones he used the great circle for were for the long ocean crossings, Oakland to Honolulu; Honolulu to Howland; Howland to Lae;  and Dakar to Natal. Using the great circle for Oakland to Honolulu instead of the rhumb line would have saved 9.6 SM and we know that Noonan didn't stay anywhere near the great circle on that flight. For the Honolulu to Howland leg, the great circle saved 0.4 SM; Howland to Lae, 0.1 SM; and Dakar to Natal, 0.1 SM. Total savings for flying all the way around the world is 10.2 SM out of a total of more than 25,000 SM. Looks to me like Williams was charging by the hour.  :D

gl
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Monty Fowler

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Re: Did Noonan use William's flight plan?
« Reply #17 on: February 20, 2012, 06:29:38 PM »

So ... does this mean that Gary is coming to DC in June to lay it all out? If so, first round is on me.

I'm serious, Mr. LaPook. Ask Ric. I put my money where my mouth is, when the occasion demands. How about you?

LTM, who had to work on this national holiday because the paper won't push itself,

Monty Fowler, TIGHAR No. 2189 CER
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« Last Edit: February 20, 2012, 06:37:12 PM by Monty Fowler »
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Irvine John Donald

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Re: Did Noonan use William's flight plan?
« Reply #18 on: February 20, 2012, 10:32:15 PM »

Monty, Gary has been trying to say to us lately that he has already laid it all out in many posts since 2002 when he joined.  He has told us, only in the last few days, that he believes in the crashed and sank theory. I don't know what he can lay out about that.  I hope he is coming to the symposium just so I can meet him. While I tend to give him a hard time on some of his posts I have the utmost respect for him and would like to discuss his ideas over a libation. Or two....
Respectfully Submitted;

Irv
 
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Gary LaPook

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Re: Did Noonan use William's flight plan?
« Reply #19 on: February 22, 2012, 01:18:56 AM »

Quote
I don't know where you ever got the idea that a great circle is any more accurate than a rhumb line, they are both equally accurate,...

So, how can a rhumb line EVER be AS ACCURATE as a well laid out great circle, unless right along the equator?  It can't - simply because a rhumb line really amounts to flying a curve (if above or below the equator) - therefore its a bit deceiving to the casual observer - and accuracy is in fact lost.  Of course as we both know, for shorter distances over land where landmarks are much more prevalent, a rhumb line is a fine thing - there's little lost, and certainly no more lost than is easily made-up by the use of occasional landmarks.

I hate to be this blunt Jeff, but you are just plain wrong. We can argue about the facts of the Earhart case but you can't argue that two plus two does not equals four. Rhumb line navigation is the standard way that ships have always been navigated and to a much higher level of precision than aircraft. I posted an experiment you can do on Google Earth here, and the example I used had both points at the same latitude. The rhumb line course between those point is exactly 90.00000000000000000000000000°, straight east from Milwaukee to the end point in Asia and if you can fly a perfect heading of 90.00000000000000000000000000000° without any errors or cross wind then you will end up at the end point. The course is exact. And this goes for every other rhumb line too. Of course flying either the great circle or the rhumb line will have the same level of errors in attempting to stay on the chosen line.

What course line, great circle or rhumb line, appears as a straight line depends on the projection used to create your chart. On Mercator charts a rhumb line is straight and the great circle appears as a curved line. On a Gnomic chart it is just the opposite, the GC is straight and the RL is curved. You use Sectional Charts when you fly. Those charts are based on the Lambert Conformal Projection and on these charts a straight line APPROXIMATES a great circle. On this type of chart the meridians are not parallel but converge toward the pole. I am sure you were taught, when plotting a course on your sectional, that you should measure the true course with your plotter placed on the meridian line nearest the midpoint of your course line, not at the meridian near your starting point. You didn't know it, but you were actually measuring and then flying the rhumb line course, not the great circle. Take out a sectional and prove it to yourself. Lay out a long course line and then measure the direction at the central meridian as you normally do. Then go back to the meridian nearest the departure and lay off the course direction you just measured. This line will go south of the first, approximate GC, line. Then where that line hits the next meridian lay off the course line again in the direction you had measured and do this with subsequent meridians. You will end up drawing a curved course line between your departure and your destination that is south of the straight line. The easiest way to do this test is to pick two spots at the same whole degree of latitude. The course you measure will be 90 degrees and if you follow the procedure you will end up drawing in the parallel of latitude since that line crosses each meridian at 90 degrees but you don't have to draw it yourself since it is printed on the chart for you already. The parallel is the rhumb line between those two points. On a Lambert chart this curved line is a rhumb line and this is the line you will actually fly without a cross wind and without looking out the window, this is the way the autopilot will take the plane. And now that you are looking at this carefully, it should be obvious that you were measuring and flying a rhumb line and not a great circle. You can't measure a single course line in a single direction and be following a great circle as Williams' careful computations demonstrate. To actually measure a great circle on the Lambert chart would require you to measure a new course at all the meridians that your course line crossed and make up a table like Williams did of the changing courses necessary to define the great circle. So the proof that you can measure and fly a rhumb line as accurately as a great circle is that you have gotten to your destinations and you have been flying rhumb lines even though you didn't know it. You have been able to get to your destinations, haven't you?  ;)  Good, then I'll call you as my first witness.

If Earhart had been able to maintain a true course of 078.1° for 2556 SM then she would have hit Howland (within the approximate 4 SM accuracy available from a course expressed to one-tenth of a degree.)
I have attached several pages from the American Practical Navigator, U.S. Navy Hydrographic Office Publication Number 9, the standard reference book used by the Navy and all American surface navigators.

gl
« Last Edit: February 22, 2012, 11:20:57 AM by Gary LaPook »
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Gary LaPook

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Re: Did Noonan use William's flight plan?
« Reply #20 on: February 22, 2012, 02:05:37 AM »

There are times when computing and flying a great circle is worth the additional effort, not because is is more accurate but because the length of the great circle is shorter than the rhumb line. Try this on Google Earth. As a starting point use 43° 00.0' North, 88° 00.0' West. For the end point use 43° 00.0' North, 85° 00.0' East and have Google Earth calculate the distance in nautical miles. You will notice that the initial course takes you almost straight north and the final course is almost straight south. I picked those two spots because it is easy to calculate the rhumb line between them. Since they are both at the same latitude, the true course is straight east, 90.00000000000000°. To compute the rhumb line distance figure the difference in longitude, 88 + 85 = 173 degrees. At the equator each degree of longitude is 60 nautical miles so the space between these two longitudes, at the equator, is 173 x 60 = 10,380 NM. At the latitude of 43° the length of a degree of longitude is equal to the cosine of the latitude times the 60 NM distance at the equator. So to find the distance between our two points we just multiply the 10,380 NM times the cosine of 43°, which is 0.731353, so the distance on the rhumb line between these two points is 7,591.45 NM. Compare that to the Google Earth result for the great circle course that passes near the north pole.



Here is the answer to my little experiment. The great circle course is only 5,644.18 NM long while the rhumb line between the two points is 7,591.45 so you would save almost 2,000 miles using the great circle. This is obviously an extreme case that I chose to illustrate this point. The initial great circle course leaving Milwauee is almost straight north, 005° T and the final course is almost straight south, 175° T. On the way the course changes through all the intermediate directions, 6 then 7 then 8.....then 90.....then 120....then, finally 175.
The rhumb line never changed, being 90.000000000000000000°.

gl
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Heath Smith

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Re: Did Noonan use William's flight plan?
« Reply #21 on: February 22, 2012, 05:33:28 PM »


An interesting example might be a proposed flight plan that FN would have created. I think that this would prove to be an interesting study.
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Erik

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Re: Did Noonan use William's flight plan?
« Reply #22 on: March 07, 2012, 07:22:29 AM »

Not sure if I've seen this line quoted before.  It's from Williams.  Not saying its true or not, but rather interesting into the 'thinking' that was going on at the time.

The Miami News - Jul 3, 1937
The man who mappeed Amelia Earhart's globe-circling flight, Lieut. Commander Clarence S. Williams, expressed belief today she may have landed at Baker island, some 40 miles south of Howland island, the dot of land she missed.
"The eight degrees may be the secret of why the fliers did not strike Howland as scheduled.  They may have allowed for the effect of a wind which may either have died down druing the night or may have been changed altogether by some gavrant storm area.  If the fliers allowed for a drift of eight degrees, and if the wind died down - so that this correction was not needed at all - they might have gone as far as 180 miles to the south of Howland island."
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Martin X. Moleski, SJ

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Re: Did Noonan use William's flight plan?
« Reply #23 on: March 07, 2012, 08:42:56 AM »

... by some gavrant storm area.  ...

"gavrant" = "vagrant"?
LTM,

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Erik

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Re: Did Noonan use William's flight plan?
« Reply #24 on: March 07, 2012, 09:32:53 AM »

"gavrant" = "vagrant"?

I guess I'm not the best editor either....

"gavrant" = (sic) =  ;)

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Martin X. Moleski, SJ

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Re: Did Noonan use William's flight plan?
« Reply #25 on: March 07, 2012, 10:11:07 AM »

"gavrant" = (sic) =  ;)

No blood, no foul. 

I like words.  I would have added "gavrant" to my collection if it had been real.  It sounds as though it should mean something.
LTM,

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Erik

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Re: Did Noonan use William's flight plan?
« Reply #26 on: March 07, 2012, 10:24:49 AM »

Sure = go ahead and add it to your colleciton!  ;D

gav·rant adjective \ˈgāv-rənt\
Definition of GAVRANT
a : Characteristic of, relating to, or having a tendency to make typograhical errors while posting in forums on the internet.


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Harry Howe, Jr.

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Re: Did Noonan use William's flight plan?
« Reply #27 on: March 09, 2012, 11:12:46 AM »


Erik
Your sense of humour is awe inspiring.

It (gavrant) could also be made an adverb ny adding ly, i.e. gavrantly,  the act of giving in the hashion of a rant, gave rantly   LOL
No Worries Mates
LTM   Harry (TIGHAR #3244R)
 
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