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Author Topic: Artifact 2-2-V-1 - aluminum 'skin'  (Read 87326 times)

JNev

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Artifact 2-2-V-1 - aluminum 'skin'
« on: June 07, 2012, 04:30:17 PM »

I am starting this string to further explore the possibility of this artifact having NR16020 as a source.

The artifact (2-2-V-1) was found in the 'Village' area of Nikumaroro during an early expedition (October 18, 1991) and is clearly an aircraft part.  Here is an earlier (original) report on the item as originally found and discussed, and another on some forensic analysis performed on the skin by the NTSB.

'What airplane' is of course a very good question.  It is not clear is that this 'skin' actually 'must' belong to NR16020 for a variety of reasons.  But some of its characteristics are consistent with a number of metal components that would have been in that plane (and of course many others), so the possibility is very interesting. 

What is not so clear is if the 'skin' is distinctive enough to be shown to have been attached to the Electra in the past: it may be a modification part that cannot be shown to match another plane, or the Electra, short of recovery of that airplane. 

My thought is to further examine the photographic evidence we have, and perhaps even another Electra (or more than one more) as an exension of the effort TIGHAR has already been able to make.  It does not appear that TIGHAR has been able to exhaust all possibilities - access isn't easy, and existing historic photographs have their limits.

Note too that even if the part were somehow definitively linked to Earhart's Electra, it still would not prove a presence of the airplane on Niku - it could have been transported there from another place.  But it would provide evidence of the airplane being in the vicinity - and either accessible by humans in the past, or in a place where it once gave up parts that washed ashore, etc.  This is also admittedly a very tough challenge: such skins don't bear serial numbers, etc.

Is it worth the chase?  I believe it is - for the education of the exercise, and for the long-shot chance it may yet prove to be a 'lead'.  Besides, it seems like a fun undertaking to be a part of the TIGHAR exercise.

I have a background in aviation maintenance, modification and repair, including extensive sheet metal training and work experience.  This makes a few notable things about this artifact stand out to me as indicators for possible fitment on the Electra (or another type perhaps, of course); as mostly mentioned in TIGHAR's data already, the following things can be observed:
- The sheet is .032" thick - if a repair item, the norm would be that it would not be used as a doubler or replacement for a skin or other component of greater thickness;
- The sheet bears rivet holes mostly of 3/32" diameter in neat rows, evenly spaced (and slightly tapered relative to each other implying this 'skin' would have been fitted to a 'transitional' area, i.e. where a fuselage or other structure tapers, etc.) -
J.N. Note: This is a rivet size that is not normally used in 'primary' structure, i.e. what we tend to think of as 'load bearing or carrying members' and including (oddly enough) fairings; there are exceptions to this: some airplanes use this size fastener in lightly-loaded sections of control surface skins where weight is critical and the 'tacking' task is not demanding.  The same is true in some fairing assemblies for the same reason, if only light stiffening qualities are required, etc.  This suggests a need to look in 'secondary' areas, i.e. places where such a broad skin might only be lightly reinforced by light-weight stringers or stiffeners, attached to relatively light structure with a minimal 'tacking' requirement present, etc.
- The sheet bears one surviving rivet which has a distinctive 'brazier' style head that is common prior to WWII; that style gave way to the AN470 'universal head' rivet around the time of WWII and is largely a 'pre-war' item.  It would not be common to find a brazier head rivet used in aircraft produced after war production was accelerated.
- The sheet is 'alclad' and bears markings that are consistent with pre-war aluminum production (a more automated process was begun during war-time production and the machine inked 'signature' is different).
- There are a very few larger diameter rivet holes surviving near at least one edge of the sheet which imply picking-up of a heavier attach point - perhaps an existing row of structurally significant rivets along a stringer or other such component.
J.N. Note: So few of these 'primary' sized holes may make a match extremely difficult as this may be the sole evidence of attachment to any primary / original portion of the parent airframe.

Ignoring for the moment 'other types' and focusing on the Electra for the simple purpose of examining a hypothesis of whether this might be from 'the' Electra, what areas of the airframe might include such an item?

One that I was not aware of prior to the symposium in Washington D.C. was a large window that was cut into the starboard side of the lavatory compartment in the Electra.  This was later covered-over in Miami, according to information in the 'Harney Drawings'.
Why consider this location for this sheet?
- Thickness: according to information in TIGHAR's material (linked above) the skins in this area are reduced in thickness from .040" forward to .032" aft; more importantly, a 'window' implies braced 'edges', and to cover it should only require a light skin of this sort in a non-pressurized airplane of the Electra's performance.
- Potential 'brace pattern' - the light rivets imply light bracing, or stiffening, across the 'membrane'; this would be needed to prevent 'oil canning' of such a cover in flight, once installed.
- Edge attachment: unfortunately not so clear, but the surviving larger rivet holes imply an 'edge' that may have been attached to heavier, braced structure which would be typical at the edge of such a window.
- While also appropriate in other areas for similar reasons, 'alclad' would be a desireable selection for an external 'panel' of this sort (so it does not 'prove' anything, but is 'consistent with' a logical choice for such an installation).

This is just one idea (and is one I am trying to investigate further at this time).  There are pictures of the starboard side of the Electra on the ground and in flight which show a tell-tale 'window cover' in the lav area as described (well aft of Fred's remaining starboard side 'nav window' in the aft cabin area), but so far I have not found a picture with enough fidelity, for me at least, to identify potentially-telling rivet / brace patterns, etc.

Any help with better pictures of this area would be appreciated, as would thoughts of additional areas where such a panel might find a 'home'.  There are of course a number of other possibilities for placement of such a skin.

Thoughts?  Ideas?  Better pictures of the starboard (right) side of the fuselage in this area (immediately aft of main cabin)?
- Jeff Neville

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richie conroy

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #1 on: June 07, 2012, 05:27:39 PM »

i know were that part goes on the Electra  :)
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Tom Swearengen

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #2 on: June 07, 2012, 06:11:44 PM »

Jeff---I have this thumbnail pic that I think was part of Purdue's archives. I dont know if this was during initial construction, or back at Burbank for the repairs after the Luke Field incident. The does appear to be a replacement panel near where the TIGHAR artifact archives place it. I think however, after seeing it in DC, that the curvature might be wrong. As I recall, the curvature flows perpendicular to the rivit lines, and in this picture, the sides of the fuselege are pretty flat, until it begins its curve near the top of the fuselege. In this case, it appears the panel isnt from that location, but might be from somewhere near it, that we cant see in the pics.
Wondering aloud---the repairs at Lockheed after Luke Field--I wonder how much -if any- skin replacement were done that far aft of the wing root, and pretty high on the fuselege.
Any thoughts?
Tom Swearengen TIGHAR # 3297
 
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #3 on: June 08, 2012, 06:26:14 AM »

i know were that part goes on the Electra  :)

What is your idea, Richie?  I'm interested!

LTM -
- Jeff Neville

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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #4 on: June 08, 2012, 07:02:43 AM »

Jeff---I have this thumbnail pic that I think was part of Purdue's archives. ...after seeing it in DC, that the curvature might be wrong. As I recall, the curvature flows perpendicular to the rivit lines, and in this picture, the sides of the fuselege are pretty flat, until it begins its curve near the top of the fuselege. ...it appears the panel isnt from that location, but might be from somewhere near it, that we cant see in the pics.
Wondering aloud---the repairs at Lockheed after Luke Field--I wonder how much -if any- skin replacement were done that far aft of the wing root, and pretty high on the fuselege.
Any thoughts?

Thanks Tom!  Do you have a larger version of this picture?  I can't blow it up effectively for some reason -

I don't know if we can fully trust the apparent 'contours' we're seeing in the artifact today - one thing the analysis revealed was that it appears to have been subject to great force when torn away from the parent structure.  So there may be some distortion there that prevents accurate matching against contours.  It is a good point though, for sure, and I got the same impression you mention - that the 'stiffener' rows of small fasteners would likely run generally 'flat' and the skin might 'roll' perpendicular to them.  Seems logical as those things go on structures, generally.

The location I've so far suggested (lavatory compartment, starboard side - window) is where you've 'wondered aloud' about, somewhat.  I don't have any information that suggests any of that was replaced as part of the repair scheme.  What I do find is the note on the Harney Drawings about AE having a large window cut in the lav starboard skin after the Luke Field incident, then having the same window covered over in Miami before departing for the rest of the final world circumnavigation. 

Somewhere I found a photo that shows a 'panel' over that window - among the Purdue items I believe.  It is actually on another laptop (my kooky 'filing habits' will kill me one day...) - I'll look for it and post it ASAP. 

At any rate, that is one possibility.  Thanks for looking this over - there are many possibilities (including of course that it didn't even come from 'the Electra'... but how a distinctly pre-war chunk of alclad like that wound up on Gardner Island is extremely interesting, no matter how it happened or what it came from.   

LTM -
- Jeff Neville

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Tom Swearengen

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #5 on: June 08, 2012, 09:50:38 AM »

Jeff---I'll what I can come up with. I thing I got that pic from the Purdue site, but I'll look around.
Tom
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Jeff Victor Hayden

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #6 on: June 08, 2012, 11:33:53 AM »

The letters A D on this artifact and, the type of rivet attached to it...

http://www.mlevel3.com/BCIT/rivetID.htm

http://zenithair.com/kit-data/ht-86-12.html
Any ideas?
This must be the place
 
« Last Edit: June 08, 2012, 11:48:19 AM by Jeff Victor Hayden »
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Jeff Victor Hayden

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #7 on: June 08, 2012, 01:11:28 PM »

Is it just a coincidence that this sheet of Alclad has the letters A D on it or, does A D refer to the type of rivet to be used ?

The 2117-T rivet is designated as an “AD” rivet, and has a dimple on the head.

http://www2.tech.purdue.edu/at/courses/at308/Technical_Links/Ac43-13-1B/CH4_4.pdf

Just a thought
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« Last Edit: June 08, 2012, 01:17:57 PM by Jeff Victor Hayden »
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richie conroy

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #8 on: June 08, 2012, 03:11:51 PM »

sorry to keep u waiting Jeff, was mad busy last night and forgot i had commented on this thread will post u some pic's that have similar patterns

a.s.a.p  :)
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Ricker H Jones

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #9 on: June 08, 2012, 05:22:19 PM »


... pictures of the starboard (right) side of the fuselage in this area (immediately aft of main cabin)?
Here is a "Before" photo of the starboard side of the Electra taken in Miami.  An "after" photo taken in Lae is on the TIGHAR site, and shows the starboard side.
Here is one more "before" photo.
 
 
 
 
« Last Edit: June 08, 2012, 05:32:11 PM by Ricker H Jones »
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richie conroy

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #10 on: June 08, 2012, 06:30:18 PM »

Jeff

Does anyone know if the partition wall's in this photo are aluminum ?

i think the skin u have posted either belongs under the mono tail or directly under cabin side windows ?

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Bruce Thomas

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #11 on: June 08, 2012, 06:43:38 PM »


... pictures of the starboard (right) side of the fuselage in this area (immediately aft of main cabin)?
Here is a "Before" photo of the starboard side of the Electra taken in Miami.  An "after" photo taken in Lae is on the TIGHAR site, and shows the starboard side.
Here is one more "before" photo.

I'm puzzled by those two pictures.  The one purports to have been made on May 20, 1937, as AE prepared to take off from Miami for Puerto Rico.  Two windows are quite visible aft on the starboard side.  But in the picture identified as being taken in Lae, I only see the one window.  When, after leaving Miami, would there have been any skinning done to cover over the other window?

Looking at the clothing worn in the picture purported to have been taken in Miami, I find those folks dressed as if it's cold.  Yes, the ground is also wet, but some of that clothing seems to be protection against lower temperatures, and that's not the Miami I've experienced in late May.  I wonder if the locale for this picture has been misrepresented by the website displaying it?  Looking at a picture showing first-day covers being presented to AE by the Oakland postmistress on March 17, 1937, the ground is similarly wet and the people (including Paul Mantz) are bundled up against the normal SF Bay area chill.  And I wonder:  does the presence of three sailors helping with the refueling further tilt the location towards Oakland and away from Miami?
LTM,

Bruce
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Malcolm McKay

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #12 on: June 08, 2012, 09:39:13 PM »

Jeff

i think the skin u have posted either belongs under the mono tail or directly under cabin side windows

No, if you examine the rivet spacing in the recovered piece, the number of rows is wrong and also that  there is no multiple rivet row as in the top and fourth rows on the skin under the cockpit window. 
« Last Edit: June 08, 2012, 09:41:24 PM by Malcolm McKay »
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Jeff Victor Hayden

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #13 on: June 09, 2012, 08:19:04 AM »

Have I missed something in this thread? Where has the idea that this piece of Alclad originates from a Lockheed Electra come from? Is there something unique that tells us it's Electra?
For sure it's airplane material, design and construction technique but that alone doesn't make it Electra. Maybe I missed something?
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Chris Johnson

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #14 on: June 09, 2012, 08:28:01 AM »

Have I missed something in this thread? Where has the idea that this piece of Alclad originates from a Lockheed Electra come from? Is there something unique that tells us it's Electra?
For sure it's airplane material, design and construction technique but that alone doesn't make it Electra. Maybe I missed something?

I could be wrong but i think the idea is to discuss the object to try and prove yes or no thta it comes from the electra.
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