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Author Topic: Post loss Transmissions. Solved?  (Read 119916 times)

Tom Swearengen

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Re: Post loss Transmissions. Solved?
« Reply #120 on: November 27, 2012, 11:31:20 AM »

Like these?
Tom Swearengen TIGHAR # 3297
 
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Ric Gillespie

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Re: Post loss Transmissions. Solved?
« Reply #121 on: November 27, 2012, 12:42:31 PM »

Like these?

No.  As I said, either AE or FN has to be standing where the guy is standing in the Assab photo.
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Dan Swift

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Re: Post loss Transmissions. Solved?
« Reply #122 on: November 27, 2012, 02:36:53 PM »

Oh and that 29" or so is considering both a fully inflated right tire and it is not sitting down in a rutt. 
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John Ousterhout

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Re: Post loss Transmissions. Solved?
« Reply #123 on: November 27, 2012, 03:03:01 PM »

In this Purdue collection photo, AE is standing in the same plane as the prop hubs, making it easy to make a fairly accurate measurement of their height compared to hers, without significant parallax.  I printed the picture to measure with a caliper, and also used MS Paint to count pixels directly, getting a range of indicated ratios of hub height/AE height(s) from 1.221 to 1.226.  Combined with her range of heights as 67 to 68 inches, these translate into indicated hub heights of 81.8 to 83.4 inches.

I assume she and the hubs are in essentially the same plane, since she is touching the prop tips with her fingers, arms stretched to their near maximum reach.  The props are nearly horizontal, so the tips are not yet far out of plane.  She cannot be standing significantly in front, nor behind the prop tips, and appears to be standing quite upright to her full height, with the possible exception of her head tilting to her left, maybe to clear the fuselage.  It is also not clear what she is wearing on her feet.

At the scale I printed the picture, I measured her height as 53.45 mm, and the prop hubs as 65.35mm.  I would be pleased to describe details of how to construct the bottom reference line, but suffice to say it runs under her feet, parallel to the hubs and horizon which is visible in the background.  There is enough information in the photo to work out the scale using the prop lengths, which I leave for some other time.  Simple pencil scaling indicates something close to 27 inches clearance from tip to ground, but there is some out of plane parallax foreshortening still needing to be accounted for, in that case.

YMMV
Cheers,
JohnO
 
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Greg Daspit

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Re: Post loss Transmissions. Solved?
« Reply #124 on: November 27, 2012, 04:51:59 PM »

I scaled the photo in AutoCAD so AE is 5'-8"
Due to her hair and shoes, her height can't be determined precisely nor do I know if she is actually 5'-8"
The prop on the right appears to be farther back, the plane is rotated slightly and the photo not taken head on so this just ballpark stuff. Two different dimensions for the props are likely due to the plane being rotated and this is taken from a photo and not a elevation drawing. I think she is more aligned with the prop on the left and I get about 2'-2". What I got is attached in the pdf
Again just quick ballpark stuff
edit, Also I used circles and should have used elipses due to the angle of the prop not bing head on
3971R
 
« Last Edit: November 27, 2012, 05:28:35 PM by Gregory Lee Daspit »
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Chuck Varney

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Re: Post loss Transmissions. Solved?
« Reply #125 on: November 27, 2012, 05:51:59 PM »

I've had a chance to sit down and correct my earlier tally of the 3105 kHz signal receptions on the Signal Catalog spreadsheet. I did a manual count (includes approximates) and came up with the following: 85 total,  44 (52%) credible, 22 (26%) uncertain, and 19 (22%) not credible.

Joe, your total of 85 includes 19 messages that have “Itasca” as the Agency/Person. These lie between message 10 and message 73, inclusive. Your total also includes message 75, which relates to 3105 kHz only in that it reports nothing has been heard on that frequency for two hours. Remove those 20 messages and your reduced total of 65 should then have a breakdown something like this: 40 (~61%) credible, 9 (~14%) not credible, and 16 (~25%) uncertain.

Quote
The reason I originally undertook the exercise was to investigate a poster's claim that a signal received on 3105 kHz stood an inordinately high chance of receiving a rating of credible.

Something like a 40 to 9 ratio of credible to not credible assessments may have motivated that poster’s claim.

Chuck
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Alan Harris

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Re: Post loss Transmissions. Solved?
« Reply #126 on: November 27, 2012, 06:10:01 PM »

Combined with her range of heights as 67 to 68 inches, these translate into indicated hub heights of 81.8 to 83.4 inches.

Just using these hub heights and correcting for the prop axes being rotated upward in pitch, the clearance comes out right around 30".  That certainly seems more reasonable to me than the 24", maybe still a bit low by the "eyeball" or "gut feel" tests, lol.  This is all approximate, to name one thing the photo doesn't show whether the plane is pitched up or down from "normal" due to ground height differences between the main wheels and tail wheel.  Also hard to say whether the main tires being on a sandy instead of a hard surface affects things significantly or not.
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Joe Cerniglia

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Re: Post loss Transmissions. Solved?
« Reply #127 on: November 27, 2012, 07:06:16 PM »

I've had a chance to sit down and correct my earlier tally of the 3105 kHz signal receptions on the Signal Catalog spreadsheet. I did a manual count (includes approximates) and came up with the following: 85 total,  44 (52%) credible, 22 (26%) uncertain, and 19 (22%) not credible.

Joe, your total of 85 includes 19 messages that have “Itasca” as the Agency/Person. These lie between message 10 and message 73, inclusive. Your total also includes message 75, which relates to 3105 kHz only in that it reports nothing has been heard on that frequency for two hours. Remove those 20 messages and your reduced total of 65 should then have a breakdown something like this: 40 (~61%) credible, 9 (~14%) not credible, and 16 (~25%) uncertain.

Quote
The reason I originally undertook the exercise was to investigate a poster's claim that a signal received on 3105 kHz stood an inordinately high chance of receiving a rating of credible.

Something like a 40 to 9 ratio of credible to not credible assessments may have motivated that poster’s claim.

Chuck

Chuck,
Thanks for your persistence.  The signals you mention between signals 10 and 73, inclusive, are receptions by the Itasca, not transmissions from the Itasca.  I assigned to any documented transmissions from any party a credibility rating of "n/a".  One should not exclude these signals from the list of 85 alleged receptions on 3105 kHz.  For message 75, I will admit that I did not look at this signal as closely as you have. The only signal heard in this reception was a weak carrier wave on 6210 kHz.  Therefore, I will exclude this signal, rated as "not certain," to obtain the following:

3105 kHz credibility = uncertain       21      25%
3105 kHz credibility = credible         44      52%
3105 kHz credibility = not credible   19      23%
total:                                             84      100%
 
I would still maintain that with a bare majority of signals registering as credible, this hardly reveals a bias of the magnitude you cite.  You excluded the uncertain signals from your ratio formula.  Your ratio was calculated as (Credibles minus all credible Itasca receptions) / (not credibles minus all not credible Itasca receptions). My ratio was calculated as (Credibles including credible Itasca receptions) / (uncertains including Itasca uncertains + Not credibles including Itasca not credibles).  I concede, however, how it might be considered acceptable to exclude uncertains. I cannot see, however, how Itasca receptions can logically be excluded.  If one takes a compromise formula, such as (Credibles) / (not credibles), one arrives at a ratio of 44 to 19.  That's still perhaps, in your view, a high number of credible 3105 kHz signals, but what's the alternative?  Discount all 3105 kHz signals as too close to Earhart's known nighttime transmitting frequency and thus the province of likely hoaxers?  If Earhart were calling for help in that region, what was she supposed to have done, broadcast on random frequencies to prove she was really her?

In any case, to my understanding, Bob Brandenburg did not use a single criteria for the acceptance of any one signal.  He used many, including SNR, message content, response timed with request for information, response timed with Earhart's pre-takeoff schedule of broadcasts, and many more. 

Joe Cerniglia
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« Last Edit: November 27, 2012, 07:46:23 PM by Joe Cerniglia »
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John Ousterhout

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Re: Post loss Transmissions. Solved?
« Reply #128 on: November 27, 2012, 09:57:22 PM »

Night-time radio long-distance propagation is DRAMATICALLY better than during daytime, generally speaking.  Night time is also the most comfortable time to sit in a solar oven trying to work a radio.  Spending the night in an aircraft solves any problem of attacking crabs, but adds the problem of wading through shark-infested water (assuming said aircraft was sitting in shark-infested water), probably best to do in daytime, unless the aircraft starts to move.

The problem with improved propagation is it is improved for everyone, including 3105 stations we've never heard of.  That's why reliable DF reports are important from several stations - to trangulate on a location, not just a frequency and single direction.
Cheers,
JohnO
 
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Doug Giese

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Re: Post loss Transmissions. Solved?
« Reply #129 on: November 27, 2012, 10:14:26 PM »

Night-time radio long-distance propagation is DRAMATICALLY better than during daytime, generally speaking.

Yes, I was trying to compare reception with original correlations with tide level. It seems the height of the tide (and therefore propeller clearance) has less to do with reception than time of day.
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Doug
 
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Alan Harris

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Re: Post loss Transmissions. Solved?
« Reply #130 on: November 28, 2012, 12:24:28 AM »

I wonder what the variance in height was when the aircraft was loaded and unloaded - if any. On the reef it would have been quite light so maybe less compression on the gear?

I missed this post earlier.  I can't say what the possible variance was, maybe someone here can; but you're right that on the reef the plane had practically zero fuel load.  That's another variable that makes it hard to establish the precise prop clearance on Niku using the photos, we don't know what the fuel state was when they were taken.
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Dan Kelly

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Re: Post loss Transmissions. Solved?
« Reply #131 on: November 28, 2012, 04:40:48 AM »

I wonder what the variance in height was when the aircraft was loaded and unloaded - if any. On the reef it would have been quite light so maybe less compression on the gear?

I missed this post earlier.  I can't say what the possible variance was, maybe someone here can; but you're right that on the reef the plane had practically zero fuel load.  That's another variable that makes it hard to establish the precise prop clearance on Niku using the photos, we don't know what the fuel state was when they were taken.

Well if Earhart had landed the aircraft after trying to find Howland and instead chancing on Nikumaroro then the fuel situation would have been pretty low so perhaps the Electra would have sat fairly high on the ground.

Has it been considered that they may not have had enough fuel left to run the engines to power the radio for those claimed broadcasts? What if folks are mistaken in their reasoning so that they are using the messages received to say that she sent them, when these messages, as some folks suggest, might have come from other unrelated sources which sort of leads everyone to claim she could run the engines and send them. What if there wasn't enough fuel left to run the engines and send them. I hope I have explained that properly.

Seems to me there is a lot of theorizing going on about them and not much to say for certain that she sent them. Been reading back on this thread and some of these "confirmed" messages are only confirmed in the minds of those claiming them aren't they. Some folk have claimed that other sources may have been responsible for some of the messages as the frequencies were not hers alone. Sorry I don't know the term for an argument that runs in a circle where unproven claims are used to support another unproven claim.
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Joe Cerniglia

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Re: Post loss Transmissions. Solved?
« Reply #132 on: November 28, 2012, 05:56:33 AM »

Quote from: Dan Kelly link=topic=944.msg22213#msg22213 date=
Has it been considered that they may not have had enough fuel left to run the engines to power the radio for those claimed broadcasts? What if folks are mistaken in their reasoning so that they are using the messages received to say that she sent them, when these messages, as some folks suggest, might have come from other unrelated sources which sort of leads everyone to claim she could run the engines and send them. What if there wasn't enough fuel left to run the engines and send them. I hope I have explained that properly.

Seems to me there is a lot of theorizing going on about them and not much to say for certain that she sent them. Been reading back on this thread and some of these "confirmed" messages are only confirmed in the minds of those claiming them aren't they. Some folk have claimed that other sources may have been responsible for some of the messages as the frequencies were not hers alone. Sorry I don't know the term for an argument that runs in a circle where unproven claims are used to support another unproven claim.

@ 8:40 of this video, you will see some work Ric did with Covington Research Laboratories to research this problem of fuel consumption versus requirements of charging the battery on the Electra.  This won't answer every possible question on the radio signals, but it's a good video presentation of this problem and a good overview of the Niku Hypothesis.

http://vimeo.com/7715435

One caveat to keep in mind is that "credible" does not mean definitively AE sent those messages.  TIGHAR is not claiming that.  What it is claiming is that if even one of the signals really was from AE, then the Electra had to be on land somewhere.

Joe Cerniglia
TIGHAR #3078 ECR
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Ric Gillespie

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Re: Post loss Transmissions. Solved?
« Reply #133 on: November 28, 2012, 07:54:49 AM »

Has it been considered that they may not have had enough fuel left to run the engines to power the radio for those claimed broadcasts? What if folks are mistaken in their reasoning so that they are using the messages received to say that she sent them, when these messages, as some folks suggest, might have come from other unrelated sources which sort of leads everyone to claim she could run the engines and send them. What if there wasn't enough fuel left to run the engines and send them. I hope I have explained that properly.

Either you have not read or do not understand the methodology and data Bob Brandenburg and I used in evaluating the post-loss messages as explained in the preface to Catalog and Analysis of Radio Signals During the Search for Amelia Earhart in July 1937. Its apparent from other questions that have been raised on this thread that you are not alone.

It is incumbent upon the users of this forum to acquaint themselves with the research that has been published before attempting to engage in discussions about its validity. I will lock this topic and open a new one called Questions about Post-Loss Radio Analysis.  On that thread I will try to answer questions that reference specific statements in the Catalog and Analysis prelude.  I will delete postings that shoot from the lip.

I will open a second new thread called "Propeller Clearance" for discussions of that subject.

The discussion of tides and water levels on the reef on this thread have been based on misconceptions. I see no point in entertaining further discussion until Bob Brandenburg's paper on that subject has been completed and published. Then questions can be directed at specific statements.
« Last Edit: November 28, 2012, 08:03:18 AM by Ric Gillespie »
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