TIGHAR

Amelia Earhart Search Forum => General discussion => Topic started by: Matt Revington on January 02, 2020, 12:26:21 PM

Title: Artifact 2-3-V-2
Post by: Matt Revington on January 02, 2020, 12:26:21 PM
This just something I have been thinking about lately, it is speculative , feel free to criticize it.

As noted in (https://tighar.org/Publications/TTracks/12_2/obj11.html) the plexiglass pieces found on Niku in the 1990s (2-3-V-2) were consistent with Lockheed's specifications for the Electra windows however, similarly  to 2-2-V-1 , it is difficult to absolutely rule out that it potentially came from later sources, particularly WWII aircraft where the canopies were commonly made of plexiglass.  The 1996 research bulletin (https://tighar.org/Publications/TTracks/1996Vol_12/40552.pdf) indicates that plexiglass was a relatively expensive and rare material (apparently only used for aircraft windows and jukeboxes) prior to WWII and production was only scaled up due to the war effort.  Testing done by a lab hired by TIGHAR  indicated that it composed of polymethyl methacrylate as plexiglass is but I see no further  details of the testing.   While the basic structure of plexiglass from before and during  the war would have been the same  I wonder if the industrial processes changed such that small contaminants from manufacture would be different and therefore prewar plexiglass could be differentiated from wartime or later plexiglass.  I have tried to sort through the chemistry literature on this but I have found nothing , but that is not totally surprising since as part of the war effort it is unlikely that improved manufacturing processes would have been widely published.  Testing (chemical or elemental analysis) of known prewar samples vs wartime samples (if available ) might be able to date these pieces as prewar. given the rarity of prewar plexiglass it would be hard to conceive of another source on Niku than the Electra.  It would still be short of the "smoking gun" level but given the difficulty in firmly dating 2-2-V-1 this might be another path to dating an existing artifact to the prewar period.

Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 02, 2020, 04:06:01 PM
Testing (chemical or elemental analysis) of known prewar samples vs wartime samples (if available ) might be able to date these pieces as prewar.

Interesting thought.  The trick would be getting our hands on documented specimens of pre-war and WWII Plexiglas for destructive testing.  (Excuse me sir.  Would you mind if we cut a small piece out of your B-17 top turret?)
Title: Re: Artifact 2-3-V-2
Post by: Matt Revington on January 03, 2020, 10:29:54 AM
You probably wouldn't need to cut pieces of plexiglass out, the paper that I link to below looks at aviation plastics (in goggles and canopies) from pre WWII until more recent times using a portable (raman) spectrometer that could be brought to the sites and test non-destructively.

https://repository.si.edu/bitstream/handle/10088/25565/mci38408.pdf?sequence=1&isAllowed=y

The downside of this is that I am not sure this technique would identify subtle manufacturing differences, at least with the way it is used here it just identifies characteristic spectral fingerprints of the type of plastics used but it may be possible to get more specific
Title: Re: Artifact 2-3-V-2
Post by: Bill Mangus on January 03, 2020, 11:19:40 AM
One source might be NMUSAF in Dayton, OH.  When the group of us visited the Museum's Restoration Facility with 2-2-V-1 we were given a walkthrough of the work then being done on Memphis BellI have an admittedly vague memory of us being show work done on the top turret in a separate room and our guide mentioning how they needed to replace some/most of the plexiglass panels in the turret and found someone who had a partial turret in his barn, I think.  Upshot is, there may still be some out there is one is committed to finding it.  The Museum may have some leftover scraps also.

I'm wondering how Lockheed would have sourced the plexiglass for the cabin/door windows.  Who was making it then and how close to the Lockheed factory were they/  Are they still around in some form?
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 03, 2020, 11:28:48 AM
Who was making it then and how close to the Lockheed factory were they/  Are they still around in some form?

Rohm & Haas held the patent on PMMA (tradename Plexiglas) in the U.S. 
They're in Philadephia, but they weren't much help when I contacted them back when we were first researching the artifact.
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 03, 2020, 12:16:22 PM
The downside of this is that I am not sure this technique would identify subtle manufacturing differences, at least with the way it is used here it just identifies characteristic spectral fingerprints of the type of plastics used but it may be possible to get more specific

I guess the thing to do would be to contact the people who did the survey and describe what we're hoping to learn.
A perennial problem in doing this kind of analysis is making sure the sample is original to the aircraft and not part of a restoration.
Title: Re: Artifact 2-3-V-2
Post by: Bill Mangus on January 03, 2020, 12:55:47 PM
Wonder if any scraps of plexiglass would still be at the site of the Electra crash in, I think it is, Idaho?
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 03, 2020, 02:13:17 PM
Wonder if any scraps of plexiglass would still be at the site of the Electra crash in, I think it is, Idaho?

We didn't see any.  Most of that wreckage was salvaged out during WWII. That airplane flew full-tilt into the mountain so there is probably shattered Plexi there if you look hard enough.  Gotta be an easier way.
Title: Re: Artifact 2-3-V-2
Post by: Walt Holm on January 03, 2020, 04:35:36 PM
There's also the Electra wreck in the Misty Fjords area SE of Ketchikan, though revisiting this site would hardly qualify as "an easier way".  It could, however, be an excellent source of Plexiglas from the original Electra production line.

I pulled out my photos of the visit from 2004, and there wasn't any plexi apparent.  But my photos were mostly promo shots of people. 

John Clauss did the photo documentation on that trip.  I've called him and he's going to look through his stash of photos to see if there's anything there.

A revisit of this site might be something to keep in mind if indeed there's a test that can distinguish between different plexi formulations.
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 03, 2020, 04:58:02 PM
I pulled out my photos of the visit from 2004, and there wasn't any plexi apparent. 

I looked at the photos I have and the only one that should show a window doesn't.  I can only think the wrinkling of the fuselage during the crash caused the window to pop out or shatter (Plexiglas doesn't wrinkle).
Title: Re: Artifact 2-3-V-2
Post by: Bill Mangus on January 03, 2020, 07:25:36 PM
Actually, I think there may be plexiglass present in that picture.  Look at the bottom of the window frame just above the horizontal stringer.  Is that a portion of  plexiglass sort of sandwiched between the stringer and frame?
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 04, 2020, 09:40:24 AM
Is that a portion of  plexiglass sort of sandwiched between the stringer and frame?

I think that's skin.  One interesting thing about the Electra wreckage in Alaska and Idaho is the blue coating on the aluminum, a corrosion inhibitor that preceded the greenish/yellow zinc chromate that came into use in 1939.  Unfortunately, there is no trace of any kind of coating or paint on 2-2-V-1.
Title: Re: Artifact 2-3-V-2
Post by: Bill Mangus on January 04, 2020, 09:54:29 AM
Seems a little thick for skin.  What I'm looking at is at the corner formed by the vertical window frame/skin and the top of the largely intact left section of the horizontal stringer running across the bottom of the window.  There isn't much of it and it barely comes out higher than the corner junction and it covers only about the middle part of the vertical piece of skin.  On the right side where the stringer is badly deformed, there's nothing showing above the corner junction.

See the right end of that moss covered rock/wood where the green leaves start.  It's straight down from there.
Title: Re: Artifact 2-3-V-2
Post by: Matt Revington on January 04, 2020, 10:01:40 AM
Do you mean the material in the yellow circle?
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 04, 2020, 10:05:43 AM
See the right end of that moss covered rock/wood where the green leaves start.  It's straight down from there.

Me too.
Title: Re: Artifact 2-3-V-2
Post by: Bill Mangus on January 04, 2020, 10:07:28 AM
Yes, right in the middle of the circle, that material which appears to be rising from in between the vertical piece and the flat, top of the stringer.  Right in the middle of the circle is where it seems to be the highest.
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 04, 2020, 10:10:28 AM
I agree. That could be Plexiglas. 
Title: Re: Artifact 2-3-V-2
Post by: Bill Mangus on January 04, 2020, 11:13:46 AM
It's not much but probably enough for testing.  If it's needed we know where it is.
Title: Re: Artifact 2-3-V-2
Post by: Greg Daspit on January 04, 2020, 12:58:46 PM
Weren’t the original cabin windows changed? The early photos showed a horizontal bar.
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 04, 2020, 01:15:49 PM
Weren’t the original cabin windows changed? The early photos showed a horizontal bar.

The windows were changed in January 1937 as part of the modifications for the world flight.  The bar, which was actually a stringer left in place for strength, was cut and standard Model 10 widows were installed.
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 04, 2020, 03:32:30 PM
The Alaska wreck is c/n 1021, a 10A delivered to Northwest Airlines 4/29/35.  It was later sold to Boston & Maine Airways and then to National Airlines before being sold to Morrison-Knudsen.  Somewhere along the way it was converted to a 10B (Wright engines instead of Pratts) and had a fuselage fuel tank installed for the long haul from Seattle to Ketchikan.  Between 1935 when it was built and 1943 when it was lost, the material for Electra windows changed several times. Whether 1021's windows were ever updated is not known but there would be no reason to change the windows unless they were somehow damaged. Bottom line: chances are 1021’s windows were different from 1055’s.  But there's really no need to take another stroll into the Misty Fjord Wilderness Area if we can do non-destructive testing.

We don’t yet know whether the non-destructive process used in the Smithsonian survey would give us the detailed information we would need.  All they were doing it distinguishing different types of transparent materials.  The question we need to answer is whether pre-war PMMA is different from wartime PMMA.  It’s a lot like the aluminum alloy question.  The basic recipe didn’t change, so we’d be looking for subtle changes.  You need enough samples from known sources to compare to your unknown sample to have statistically significant results. 

The closest Model 10 to Earhart’s is the New England Air Museum 10A, 1052 (just three airplanes away from 1055) but it has been extensively restored. No way to know if it has the original windows BUT if its windows test out identical to 2-3-V-2 and different from a selection of WWII aircraft, that would be pretty significant.  So we’re back to the question of whether the non-destructive process would give us the detail we need.  I'll see if I can contact the people who did the Smithsonian study.
Title: Re: Artifact 2-3-V-2
Post by: Greg Daspit on January 04, 2020, 03:55:37 PM
Why were the original windows not standard? How is the book coming along?
Title: Re: Artifact 2-3-V-2
Post by: Matt Revington on January 04, 2020, 05:01:12 PM
As far as the windows it is explained here https://tighar.org/Projects/currentnews.html


Also Ric you are right to contact the people at the Smithsonian, they had a second paper related to the one I previously mentioned discussing the development of the portable probe they used to analyze the samples in that study in situ , although it was 5 years ago I doubt it is generally available to other researchers
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 05, 2020, 11:44:18 AM
Why were the original windows not standard?

The link Matt found (thanks Matt, I had forgotten about that) explains the thickness but it doesn't answer your question. 
What we see as a "bar" through the original windows is actually a stringer and its removal speaks to the unprofessional nature of Earhart's entire operation.  In January 1936, confronted with the need to deliver an Electra with a 50% greater maximum gross weight than the airplane was designed for, Lockheed eliminated all but two of the ten standard windows and left in place a stringer that, on the standard Model 10, would be cut to accommodate each window.  As delivered in July 1936, the "10E Special" featured an immensely strong uninterrupted fuselage structure of stringers and bulkheads broken only by the cabin door.  In January 1937, as the airplane was being prepared for the world flight, navigator Harry Manning (who had no experience in aerial celestial navigation) insisted on an elaborate "navigator's station" in the rear cabin.  He wanted mounts for a pelorus (sighting device) at each cabin window, but the stringers would be in the way so they were cut out and standard windows installed.  He felt he needed optically correct windows for taking star sightings so a special window was put in the cabin door and a large window was installed on the starboard side in the lavatory - all of which butchered the integrity of the fuselage structure created by Lockheed to accommodate the stresses caused by the heavy fuel load. The work appears to have been carried out at Mantz Air Service without benefit of Bureau of Air Commerce approval or inspection.

How is the book coming along?

The further I get into the story of c/n 1055 the more it becomes the story of Amelia and the people around her.   The simple progression of first-they-did-this-then-they-did-that would be a useful guide in dating the many photos of the airplane, but it's the "why" the changes were made that sheds much-needed light on who she was and how her career and life came to a tragic end. The book needs to be broader in scope than I originally contemplated.  The same thing happened with my first book.  It started out to be a TIGHAR Tracks article, then a book, about the post-loss radio signals and morphed into Finding Amelia - The True Story of the Earhart Disappearance. I'll undoubtedly need the Forum's advice as I work out the boundaries of this book but, wherever we end up, everyone who has donated to the book project will get a signed copy when it's finished.
Title: Re: Artifact 2-3-V-2
Post by: Greg Daspit on January 06, 2020, 04:51:43 PM
Why were the original windows not standard?

The link Matt found (thanks Matt, I had forgotten about that) explains the thickness but it doesn't answer your question. 
What we see as a "bar" through the original windows is actually a stringer and its removal speaks to the unprofessional nature.

Thanks for the detailed answer Ric. You hit at the heart of what I was concerned about since seeing the separation in a seam of skin at the belly of the plane in the Nilla Putnam photo which seems to have appeared after the hard landing in Miami.
I was wondering if the stringer was part of the original design for c/n 1055 specifically.
Though the non-approved removal of one stringer at each of the two small windows may not be as significant as the multiple rows cut away for the big lavatory window it does seem to add to the evidence there was a pattern of reckless decisions.

I think boundaries that include the latest that has been learned about the evolution of the plane and its operation, the effects “modifications” had on the final flight and the pattern of decisions that lead to the lost flight would make a historically significant book. IMHO

Title: Re: Artifact 2-3-V-2
Post by: Ted G Campbell on January 07, 2020, 01:25:58 AM
Ric,
Something odd has jumped out to me when watching "Expedition Amelia"! (about the third time)

Notice the cockpit entrance hatch early in the video, it folds out toward  the wing - showing three windows!

Then you see the hatch folds toward the C/L of the plane.

Then again toward the wing.

Then over the C/L of the plane.

Has someone patched together a video for TV rather then show the true story of the last flight?

However, if the clips they show are real, have we looked at the "patch" may have came from above the cockpit rather then the rear window?

Just an observation.

Ted Campbell

 https://tighar.org/smf/index.php?action=post;topic=2109.0;last_msg=43549#
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 07, 2020, 08:39:51 AM
Notice the cockpit entrance hatch early in the video, it folds out toward  the wing - showing three windows!

The three windows in the shot are the windshield, the small cockpit window and the sliding cockpit slide window.

Then you see the hatch folds toward the C/L of the plane.

When Earhart's airplane was delivered in July 1936, the cockpit hatch opened outward as it did on all Electras.  The hatch was an emergency exit and seldom used on the passenger version.  The crew entered through the cabin door and walked forward to the cockpit.  Earhart's cabin was encumbered with fuel tanks so getting to the cockpit was awkward, but the outward-opening emergency hatch was also awkward.  In October 1936, while the airplane was at Purdue, Bo McKneeley reversed the hatch so that it opened toward center-line, making it easier to use.

However, if the clips they show are real, have we looked at the "patch" may have came from above the cockpit rather then the rear window?

Yes, we considered that. No, it didn't.
Title: Re: Artifact 2-3-V-2
Post by: Matt Revington on January 07, 2020, 09:22:06 AM
That hatch had other issues  also  during the Bendix race in September 1936.

"Amelia Earhart had flown in many air races prior to the 1936 Bendix. She had only
recently taken delivery of the new Lockheed Electra 10E from Purdue University as
   her "Flying Laboratory" Her co-pilot for the race was Helen Richey, one of America's
top  women pilots.  Unexpectedly the emergency  cockpit escape hatch blew open
 almost sucking both pilots out,  they were able to secure it with a rag till they landed
   at their Kansas City fuel stop where they  were able to wire it closed. The open hatch
caused  much  lost time."
From http://www.airrace.com/1936NAR.htm
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 07, 2020, 09:31:56 AM
Unexpectedly the emergency  cockpit escape hatch blew open
 almost sucking both pilots out,  they were able to secure it with a rag till they landed
   at their Kansas City fuel stop where they  were able to wire it closed. The open hatch
caused much lost time."

Yeah, think about that.  It was a standard hatch.  Hatches on Electras did not routinely blow open in flight.  Earhart and Richey departed Floyd Bennett Field in the pre-dawn darkness.  The hatch blew open about 20 minutes later.  Sounds like somebody didn't secure the latch properly.  Assuming AE flew from the left seat, she was the last person to enter the aircraft.  Pilot error.
Title: Re: Artifact 2-3-V-2
Post by: Daniel R. Brown on January 07, 2020, 05:21:10 PM
Saturday, 5 June 1937. One day layover in Fortaleza, Brazil; crew rest. AE: “I shopped this morning for sponge rubber to replace some wearing on the cockpit hatch.”

Dan Brown, #2408
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 13, 2020, 12:03:18 PM
I've benn corresponding with Odile Madden, the primary scientist on the NASM study. She says,
"Raman and XRF are unlikely to give you any useful information about the date of the PMMA. Raman could tell you it’s PMMA, and XRF only identifies elements in the periodic table that are heavier than, say, silicon.  PMMA is just carbon, hydrogen, and oxygen.  If you had a sample of window from a contemporaneous 1936/7 Electra to compare with your sample, it might be possible to do some trace element analysis."

So we're back to destructive testing, provided we could get our hands on an original sample to test.  But there's another question to answer.  Were the cabin windows on NR16020 really Plexiglas?  The engineering order calls for "shatterproof" which we always took to mean Plexiglas, but it might also mean laminated safety glass.  How could we know?  If we had a surviving Lockheed 10 built after January 1937 that still had the original windows, Raman could tell us if they are PMMA, but I'm not aware of such an aircraft.  The Electra at the New England Air Museum is only three serial numbers from Earhart's, but its windows were all replaced during restoration.  The same is probably true of all restored Electras.  The old windows tend to yellow and craze so they get replaced.
Title: Re: Artifact 2-3-V-2
Post by: Matt Revington on January 13, 2020, 12:47:10 PM
This google book preview of "Kelly" by Clarence Johnson mentions on page 50/51 that starting in 1937 the Model 14 Super Electra used "a new Plexiglas for windows" .  If we believe this then Lockheed was using it at that time, of course it does not say if it would be put in the 10E.

https://books.google.ca/books?id=S51fBgAAQBAJ&printsec=frontcover&dq=kelly+more+than+my+share&hl=en&sa=X&ved=0ahUKEwjLsfP5qYHnAhWIiOAKHb1ZBKUQ6AEIKTAA#v=onepage&q=kelly%20more%20than%20my%20share&f=false
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 13, 2020, 01:31:59 PM
Thanks Matt.  Very interesting.  The Model 14 first flew on 29 July 1937.  Construction of the prototype began "early that year."  (Lockheed Aircraft since 1913, Francillon, Naval Institute Press, 1987) 
Title: Re: Artifact 2-3-V-2
Post by: Greg Daspit on January 20, 2020, 05:05:04 PM
Regarding evidence that suggests the patch was added because of structural problems after the hard landing:
Using the Miami Nilla Putnam photo and the Miami Taxi photo, or the new film he is analyzing.
Do you think Mr. Glickman can do a proportion study to determine if the patch was lapped over an added reinforcing or splice stringer to the top or bottom of the previous opening? This study would use the seam to the upper right of the patch as a reference.
Compare the X to Y proportions in the Nilla photo to the  X to Y proportions in the Taxi photo to see if one edge related to the seam got bigger? Maybe both? See attachment

Edit: Not sure the best place for this post. The removal of the cabin window stringer noted in this discussion is what instigated the question
Title: Re: Artifact 2-3-V-2
Post by: Ric Gillespie on January 21, 2020, 09:29:19 AM
Regarding evidence that suggests the patch was added because of structural problems after the hard landing:

If the window was removed and the patch installed to rectify the weakness caused by cutting stringers to make a hole for the window, I don't think adding stringers in the places you suggest would do anything to strengthen the empennage.  To restore the integrity of the structure it would be necessary restore the continuity the original stringers. If that's what they did, rivet lines on the patch should coincide with rivet lines on the pre-window empennage.  Based on what we can see so far, they don't.  Only the bottom row of large rivets matches up with an original stringer.  The four rows of small rivets don't line up with anything.  In the attached illustration the standard rivet lines/stringers are in blue and the artifact rivet lines are in red.

I think the reason for removing the window was that the window cracked due to the hard landing and flexing of the weakened empennage.  Flexing of the weakened empennage also caused the deformation we see in later photos of the patch.

Do you think Mr. Glickman can do a proportion study to determine if the patch was lapped over an added reinforcing or splice stringer to the top or bottom of the previous opening?

We already know the patch covered a larger area than the window.  Jeff is just now getting to the point where he can start to confirm the lines of small rivets.  It will be interesting to see if we can confirm rivet lines that suggest the presence of the added stringers/stiffeners you propose.