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 71 
 on: January 28, 2019, 07:04:19 AM 
Started by Brian Tannahill - Last post by Ric Gillespie
Could the owner of that instrument have removed an NO collimation certificate in order to install the felt lining?  Or put the lining right over the certificate?

Yes, that's possible but the photo I posted does NOT show the box for the Ludolph sextant once owned by Noonan and now at the National Museum of Naval Aviation in Pensacola.  My bad.  That box is for another Ludolph sextant we found on eBay and asked the owner to send us pictures. I'll correct that post.

The interior of the Pensacola box is shown in a 1999 TIGHAR Tracks article about the box. The interior has no felt lining and there is no certificate.

 72 
 on: January 28, 2019, 02:05:46 AM 
Started by Brian Tannahill - Last post by Martin X. Moleski, SJ
Here's a photo of that box (Pensacola loaned it to us).  See any certificate?


No.


But the green felt (?) is unusual.


It seems to me that most of the pictures of boxes I've looked at since 2010 did not have any felt in them at all.


Could the owner of that instrument have removed an NO collimation certificate in order to install the felt lining?  Or put the lining right over the certificate?


OH--and the fact that the two numbers for that box are scrawled on the bottom in pencil suggests to me that it might be a WB/WS example.  Many of the boxes in our list have got a Brandis serial number on the box.  That is one way of determining a mismatch between the box and the sextant.


It gets complicated quick ...

 73 
 on: January 28, 2019, 02:00:11 AM 
Started by Randy Conrad - Last post by Martin X. Moleski, SJ
At one time she was asked the question of navigation and being off course and she said that the pilots had a way of literally throwing their navigation off to keep on track with head winds. True or False.

There is a grain of truth in there somewhere.

But it is not "throwing their navigation off" nor is it a matter of "keeping track with head winds."

Cars, as a general rule, are not blown off course by cross-winds.  The friction between the tires and the road means that, as a general rule under normal conditions, the car goes where you point it.

An airplane lacks that helpful contact with the ground.  Only if the wind is coming directly from the heading you want to fly to reach your destination can you use your compass to steer you to your destination.  If the cross wind is directly perpendicular to your intended path, it will cause you to move with it in that direction even though you are keeping the nose of the airplane in line with a different compass heading.

NASA article on "Cross Winds."



In order to make your ground track align with your path to your destination, you must now point the nose of the aircraft into the wind just the right amount to offset the force of the wind that is carrying you off-course. 

If you don't know the exact velocity and angle of the cross-winds, you have to guess the right amount of compensation to dial in between a line drawn on the map from where you are to where to want to be and the actual line being drawn across the ground by the combination of your own airspeed and orientation with the angle and strength of the cross winds.

Fred could only give Amelia new vectors to fly when he could establish their position with some degree of certainty, which would help him to measure the force of the crosswinds they had encountered during the time since their last fix.  There was also a drop tube and a drift sight built into the Electra so that the navigator in the rear could drop flares (?) on the ocean and estimate drift.  See the "Luke Field Inventory," which shows that AE had "Aluminum Direction Bombs" on board when she attempted to take off from Hawaii--"containers of aluminum powder to be dropped onto the surface of the water as a target for a drift meter so that a navigator can judge wind direction and speed." 

That these containers were meant to burn is my own conjecture or unclear memory.  I can't find a simple description of them on Google at the moment.  In daylight, I think the navigator could look at wave patterns with the drift sight without having to drop any markers.

 74 
 on: January 27, 2019, 10:36:48 PM 
Started by Randy Conrad - Last post by Randy Conrad
Spent a wonderful afternoon in Quinter, Kansas listening to Ann Birney depict the life of Amelia Earhart. Ann has been doing this since 1995 and was the first person to portray a historical figure in the Smithsonian's Air and Space Museum several years ago. One of things I admired about her was her ability to take you back to 1937. At times you didn't know if you were speaking to Amelia or Ann the historian. Overall, her speaking engagement was very interesting and almost to the point you could hear a pin drop. At one time she was asked the question of navigation and being off course and she said that the pilots had a way of literally throwing their navigation off to keep on track with head winds. True or False. Anyway, I had never heard of this before...feedback please!!!! Anyway, she was really addiment about giving Ric credit and the Tighar organization and its members for keeping the search ongoing and letting the finds speak for themselves. I think her performance was really grand!!!

 75 
 on: January 27, 2019, 12:39:59 PM 
Started by Brian Tannahill - Last post by Ric Gillespie
What do we know of the numbering/inspection/WB/WS of the sextant Noonan loaned to his student that was returned?  Was is similar?

Great question.  Here's a photo of the box for a Ludolph sextant we found on eBay and asked the owner to send us pictures.  See any certificate?

 76 
 on: January 27, 2019, 10:42:20 AM 
Started by Brian Tannahill - Last post by Ricker H Jones
What do we know of the numbering/inspection/WB/WS of the sextant Noonan loaned to his student that was returned?  Was is similar?

 77 
 on: January 27, 2019, 10:08:23 AM 
Started by Martin X. Moleski, SJ - Last post by Ric Gillespie
Were there radio navigation aids available in that area at that time?

Great question.  Yes, there were two forms of radio navigation aids available:
• Low frequency radio ranges
• Non-directional radio beacons

The beauty of the Low Frequency Range was that it required only a receiver, a suitable antenna, and earphones.  Low Frequency Ranges could be used to fly the approved cross-channel routes. None of the ranges in England would be of much use in navigating from Twinwood to Portland Bill but once you got closer to France you could use LF Ranges to navigate Paris.
 Based on photos we've seen, few C-64s were equipped with loop antennas ("footballs") so non-directional beacons were probably of no use to Morgan.  If Morgan flew from Twinwood to Portland Bill he probably did it by dead reckoning and pilotage.  Tricky in low ceiling and visibility but I've made longer flights under those conditions.  As Lindbergh supposedly said, "The only thing wrong with dead reckoning is the name." 

 78 
 on: January 27, 2019, 08:43:48 AM 
Started by Brian Tannahill - Last post by Ric Gillespie
Thanks Marty.  It's good to quantify what we can, but it comes down to a qualitative judgement about probability.  We know that Gallagher found the box for Brandis sextant 3500/1542 in the immediate vicinity of the bones. The question is, how did it get there?

Taking refuge in Occam:  Which of the imagined explanations requires the least multiplication of necessities?  In other words, which of the explanations relies upon the fewest improbable events?

For the box Gallagher found to have come from Bushnell requires:
• The box to have been brought shore at Gardner and lost or abandoned near the bones.
• The person or persons who lost or abandoned the box either did not notice or did not think it was worth noting the presence of the skull, partial skeleton, shoe parts, fire, dead birds and dead turtle seen later.
• The box to have been modified by someone to look like it had most recently been used merely as a receptacle.
• The N.O. certificate on the inside lid of the box went missing 18 months after it was put there by the Naval Observatory.

These are all possible but improbable events.
 
For the box to have been brought there by Amelia Earhart requires that:
•  Noonan have the box for sextant 3500/1542 but not the sextant.
•  Noonan have the box for sextant 3500/1542 with him on the world flight.
•  Earhart modify the box for use as a receptacle and bring it with her to the Seven Site.

These events are all possible and none seem to be particularly improbable. 

 79 
 on: January 27, 2019, 12:09:49 AM 
Started by Brian Tannahill - Last post by Martin X. Moleski, SJ
When the Naval Observatory overhauled a sextant they pasted a Certificate of Inspection to the inside of the box lid.  When the N.O. serviced 3500/1542 they should have pasted such a certificate to the box it was in.  The box found near the bones roughly two years later had no such certificate or the Brits would have known it was an American box instead of speculating about it being English or French.  The inside of the lid is a protected location even in the harsh Niku environment.  That’s a strong argument that the sextant that had been in the box found with the bones was not the sextant assigned to USS Bushnell. 
<sigh>

This happens all the time.

I don't think I have ever kept track of data and not wished halfway through that I had been paying attention to more elements than I did at the beginning.

I did not create a column to keep track of which boxes have certificates and which do not.

Many of the discrepancies between the N.O. number engraved on the sextant and other numbers on the box come from the extant certificates, but it is not easy to extract the number of boxes-lacking-certificates from the list.

I don't have time this morning and may not have any time soon, but I am moderately confident that the vast majority of the entries I have made in the table come from people posting in the Forum thread, "Can you add to the list of sextant numbers?".

Ah!  Now that I look at the fields that I created for the table, one is for "Inspection date."

|-
! Maker
! Maker No.
! Navy No.
! Inspection date
! Comments
! Bubble
! N.O. # on box

So we can be pretty confident that the presence of an "Inspection date" means that a certificate is in the box.

I'm off to see the Wizard ...

Back from the land o' data.

I count 45 entries with inspection dates.

I count 27 entries that are marked "Wrong Sextant" (WS) or "Wrong Box" (WB) and that lack an inspection date.

There are 5 entries that are marked WS or WB among the 45 that have got inspection dates.

If you go look a the list of sextants, you can change the sort order of the table by clicking on the small pair of triangles or arrowheads next to each field name.  When you click on the "Inspection date" sort marker, all of the inspection date records will float to the top.  So, too, with all the other fields. 

Some of the sorting produces nonsense lower down the table.  That's life with tables.  If you get mixed up, just refresh the page and the table will start out again in its original state.

Time for coffee and pastry.


After breakfast -- counting coup

Getting the right statistic out of the information in the table is a little tricky.

I made the table.

I'm not sure I'm counting things write.

Here is how things got complicated.

1. I wanted to keep track of pairs of numbers.

2. After keeping track of numbers for a while, it became apparent that some sextants were in the wrong box.

3. Because of the mixups, we could get one pair of numbers from the sextant box and another pair of numbers from the sextant in the box.  I put both numbers in the table. 

4. "WS" indicates that it is an entry for numbers taken from the box, even though the box contains the "wrong sextant."

5. "WB" indicates that the entry is for a pair of sextant numbers engraved on the sextant, even though those numbers disagree with numbers on the box.  This is how we know that the sextant is in the "wrong box."

6. Therefore, the same discrepancy may be recorded twice, I think: one entry for the box numbers, marked "WS," and one entry for the sextant numbers, marked "WB."

Checking the table now to see if there are the same number of WS and WB records.

...




Nope.  13 WS records and 19 WB.


Why?  Because sometimes we could tell that there was a discrepancy between the Brandis numbers on the sextant and on the box but could not derive a pair of numbers from the information we had about the box. 


Here is a weird record:

Brandis 4193
N.O. 4161
1919-04-02

Pictures show 4193 stamped on arc and inked on the box. N.O. 4161 also on arc, according to the text. Maker's number 5317 on the inspection certificate. So there is quite a discrepancy!

A theory to account for the apparent facts:

1. Brandis 5317 was put into the box for Brandis 4193 and sent to the N.O. for collimation.

2. The NO put a certificate for Brandis 5317 on the box and returned it to the sender.

3. Someone put Brandis 4193 back into its own box.

Cue sounds of wailing and gnashing of teeth.

OK.  I'm off to do some more sorting and counting.



...

I've attached an ODS spreadsheet that makes it easier to resort the data and count things in the columns.

  • 97 Naval Observatory numbers
  • 7 of these entries lack a maker's number
  • 90 pairs of numbers
  • 31 of 97 entries are marked "WB" or "WS"
  • 18 "WB"
  • 13 "WS"
  • 45 inspection dates recorded
  • 4 of the 45 are marked "WS"
  • 1 of the 45 is marked "WB"
  • 26 of the 52 pairs of numbers that lack inspection dates are marked "WB" or "WS"
Should we say that each of the WB/WS entries is a separate event?

I'm inclined to say yes.

Every sextant put in a wrong box produced a correspondingly mismatched WB/WS pair.

If we start with 100 properly matched sextants and boxes, then determine that we have seen 15 mismatches, that (to me) implies another 15 that we haven't yet seen up close and personal.

31/97 is 32%.

Even boxes with collimation certificates do not always contain the right sextant.  5 out of 45 (11%) are mismatched. 

For entries that lack collimation dates, the misplacement rate is 50%: 26/52.

It's possible that this big discrepancy is due to our inability to handle each sextant and box personally.  It may be that the sellers or owners just didn't photograph the certificate.  Because we weren't asking the question about a 1-to-1 ratio between instruments that had Naval Observatory numbers and boxes that had collimation certificates pasted inside them, we didn't keep track of whether the ABSENCE of an inspection date meant the ABSENCE of a certificate.  I think some of the certificates had numbers on them but did not have the date when the adjustment was made--but I have been wrong in the past and could be wrong now.

Some of this information might be contained in the thread about sextant numbers.  I'm not ready to go back to read those 482 posts this morning.  I have guests coming over for Mass and then for a quest to find cheap eats in the neighborhood.

 80 
 on: January 26, 2019, 05:13:08 PM 
Started by Brian Tannahill - Last post by Ric Gillespie
As an aside to another discussion, Richard Jantz asked me:
"I am still puzzled  by the improbability of the box ending in association with the bones and no one noticing them. You say that the sextant  was among those sent to the NO for general overhaul. Is it possible that the sextant ended up in a different box, making the original available to Noonan  to take with him on the Earhart flight?"

I replied:
Thank you for that question.  It started me down a path that led me to a bit of an epiphany.

First of all, yes, it’s possible.  Over 20% of the Brandis sextants we have documented are in the “wrong” box (i.e. the box for a different Brandis).  For Noonan to end up with the box for Brandis sextant 3500/1542 and the sextant itself end up assigned to USS Bushnell, the switch would have to have occurred before the box left the U.S. Navy inventory.  I know of no reason that could not have happened.

But here’s the forehead-slapper:
When the Naval Observatory overhauled a sextant they pasted a Certificate of Inspection to the inside of the box lid.  When the N.O. serviced 3500/1542 they should have pasted such a certificate to the box it was in.  The box found near the bones roughly two years later had no such certificate or the Brits would have known it was an American box instead of speculating about it being English or French.  The inside of the lid is a protected location even in the harsh Niku environment.  That’s a strong argument that the sextant that had been in the box found with the bones was not the sextant assigned to USS Bushnell. 

It’s still a bizarre coincidence that the box and its original occupant ended up on or near the same remote Pacific Island, but not nearly as improbable as a Bushnell surveyor losing a sextant box near the bones without seeing them.

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