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Author Topic: Artifact 2-2-V-1 - aluminum 'skin'  (Read 79955 times)

Jeff Victor Hayden

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #15 on: June 09, 2012, 09:08:13 AM »

I see Chris, just checking to make sure I didn't miss something.
I guess it would be good idea to start at the beginning then and try to identify the features which point to a particular era, make and model of aircraft or, anything else about it that makes it unique.
Here's my first point:
Is it a repair section or, a mass produced sub-section and, how would we be able to tell the difference?
This must be the place
 
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #16 on: June 09, 2012, 09:38:39 AM »

...Where has the idea that this piece of Alclad originates from a Lockheed Electra come from?

The idea that it might originate from an Electra - namely NR16020 - came from TIGHAR finding the item on Niku in the village during an early expedition there.  As you state, it is an idea only, so far.

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Is there something unique that tells us it's Electra?

No, only that it appears to be a pre-war aircraft related item because of what could be discerned of how it is marked, what material it is and by the characteristic of the one surviving rivet (a brazier head type - common to pre-war rivets).  It could be from an Electra - or any number of other airplanes as well.  It is possible, however remote, that we could eventually show that it came from the Electra; we'd likely never prove what else it may have come from.

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For sure it's airplane material, design and construction technique but that alone doesn't make it Electra. Maybe I missed something?

No - you are correct.  My reason for raising this discussion was simply to explore the possibility of it being identified as something that came from the Electra by examination of primary and secondary structural elements and possible fitment as part of original, repair or a modification scheme on that plane. 

I'd say that any eventual 'success' in that exercise is likely to be a very long-shot, but it makes an interesting exercise to me and I thought others might enjoy the 'chase' too.

LTM -
- Jeff Neville

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« Last Edit: June 09, 2012, 09:52:50 AM by J. Nevill »
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #17 on: June 09, 2012, 09:43:01 AM »

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.

I agree, Malcolm.

I think we need to examine other, likely more obscure areas (many more easily viewed areas have been examined - and I think 'secondary structure' needs closer attention due to the light construction character of this panel). 

LTM -
- Jeff Neville

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« Last Edit: June 09, 2012, 09:54:47 AM by J. Nevill »
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #18 on: June 09, 2012, 09:52:11 AM »

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 ?

Richie, I think the partition bulkhead behind the navigator is a possibility as a 'light structure' that could have been built with such light fasteners to hold light stiffeners - but I see one thing in the artifact that suggests that would be a remote possibility: the neat rows of 3/32" rivets are tapered as they progress one end to the other.  This suggests that the part lay in some area where the lines of structure tended to taper in that way, or in some zone of transition.  That's not out of the question for such a partition, but I wouldn't expect it. 

One problem we have with that photo to is that the bulkhead appears to be covered with soft goods, so we'd need to find one without the interior being finished (or find 'an Electra' in that condition that we could examine).

My current focus is on the added window in the lav - very large - and said to have been covered-over in Miami prior to departure, at least by information in the Harney Drawings.  Ricker has provided a couple of pictures of that, and somewhere (still trying to dredge it back up) I have one or two showing the 'covered' window.  One 'problem' with that big lav window is that at least the outer edges (upper and lower) appear to be parallel - which offsets the notion of the 'tapered' lines for the small rivets.  That said, the window does lie in a tapered section where surrounding elements tend to converge as they transition aft, so whoever covered that window could have easily adapted any stiffener placement to better match the surrounding structure elements in their alignment.  A good shot of that covered window is what we need to examine this idea further.

The lavatory window is of course simply another possibility, and there are no doubt many others.  Good work - keep looking!  Can you get a clear picture of that window in its covered state?  Ricker's are a good start but maybe we can get a closer more clear shot of the area with the 'cover' in place?

LTM -
- Jeff Neville

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« Last Edit: June 09, 2012, 09:55:51 AM by J. Nevill »
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Ricker H Jones

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #19 on: June 09, 2012, 10:20:56 AM »

The lav bulkhead may have been of similar construction as the cockpit bulkhead shown in this photo.
 
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #20 on: June 09, 2012, 10:41:42 AM »

The lav bulkhead may have been of similar construction as the cockpit bulkhead shown in this photo.

Excellent, Ricker - thanks for this and the other photos!  This is worth studying.

Here are some other photos of the lavatory window - open and in the covered state.  I have marked some to emphasize the area in question.  A crafted-cover is evident in the 'covered window' shots; it is beyond my abilities to accurately judge, but the 'added skin' cover appears to display some slight waviness as the light interacts with the surface in one of these shots - suggestive of a fairly light, hand-crafted covering. 

I cannot make out any 'stiffener lines / 3/32" rivet lines' so far either, but they would be very small if there.  I want to study this picture more closely - and if there are better ones available of the area they might yield a clue.

- Jeff Neville

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Chuck Varney

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #21 on: June 09, 2012, 11:43:54 AM »

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.  . . .  And I wonder:  does the presence of three sailors helping with the refueling further tilt the location towards Oakland and away from Miami?

Bruce,

The first “Before” link that Ricker provided doesn’t work for me, but if this is the photo in question, it was not taken in Miami on 1 June 1937 (or on 20 May 1937). The aircraft is in its first-world-flight configuration so the photograph was taken on or before 20 March 1937, the date of the Luke Field takeoff attempt.

Going on your Oakland assessment for the location, I found this photo taken in Oakland during preparations for the first world flight. It is a port side view of the scene shown from the starboard side in the link above. It seems likely that the date is 17 March 1937, the day of departure for Hawaii.

Chuck
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #22 on: June 09, 2012, 12:11:10 PM »

It sure appears that the two photos you've shared are the same plane, same event, same people, same day, Chuck - just different views.  Good catch.

LTM -
- Jeff Neville

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Chuck Varney

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #23 on: June 09, 2012, 12:32:47 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.

Tom,

I didn’t see your thumbnail among the photos in the Purdue collection, but I found this one that appears to have been taken about the same time as your photo (during initial construction in 1936). It shows quite a bit of skin detail.

Chuck
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #24 on: June 09, 2012, 12:54:02 PM »

Good find, Chuck.

If we can find any that are further aft - of skins behind the station that defines the aft-edge of the door it would help us see rivet patterns in that area.  That would coincide with the lavatory area (and starboard or port side skins are probably similar in a 'stock' airplane).

What would be really telling about the covered-over lavatory skin are any photos of this quality in that area that show that detail.  That could tell us something about the larger rivets and how they are spaced - whethere there may be a match to the larger rivet hole pattern on the artifact (and how it would have attached to the parent structure).

It probably will be important ultimately to get photos of the as-modified airplane because just sticking an 'after-market' skin over a window opening does not guarantee that any original structure would be 'picked-up' by the installer other than at the edges - it (former structure) wouldn't be there in the middle of the aperture.  Accordingly, whoever installed the covering 'skin' to close the window on NR16020 may have improvised lightweight stiffeners over the middle of the 'membrane' formed by the panel, and only approximated fuselage taper when laying the fastener rows out. 

If my thought on how the window 'blank' was installed over the opening is correct, what would have been important more than anything else is damping 'oil can' effects in the new skin.  When able I'll try to make a sketch of this 'notion' and post it here to give a graphic idea of what I'm trying to describe.

Thanks for digging out these photos - very helpful!

LTM -
- Jeff Neville

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Bruce Thomas

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #25 on: June 09, 2012, 01:50:07 PM »

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.  . . .  And I wonder:  does the presence of three sailors helping with the refueling further tilt the location towards Oakland and away from Miami?

Bruce,

The first “Before” link that Ricker provided doesn’t work for me, but if this is the photo in question, it was not taken in Miami on 1 June 1937 (or on 20 May 1937). The aircraft is in its first-world-flight configuration so the photograph was taken on or before 20 March 1937, the date of the Luke Field takeoff attempt.

Going on your Oakland assessment for the location, I found this photo taken in Oakland during preparations for the first world flight. It is a port side view of the scene shown from the starboard side in the link above. It seems likely that the date is 17 March 1937, the day of departure for Hawaii.

Chuck

Awesome find, Chuck!  Good job!
LTM,

Bruce
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Jeff Victor Hayden

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #26 on: June 09, 2012, 02:36:06 PM »

Jeff, there's a lot of stills on this link that show the inside of the Electra viewed from outside the fuselage door. You can see the FN's navigation window and, where the other original window should be but isn't. Looks like these images were aquired after the skinning over.

http://www.criticalpast.com/video/65675063657_Amelia-Earhart-Putnam_Fred-Noonan_transatlantic-flight_Fred-Noonan
This must be the place
 
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Chuck Varney

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #27 on: June 09, 2012, 02:50:58 PM »

If we can find any that are further aft - of skins behind the station that defines the aft-edge of the door it would help us see rivet patterns in that area.  That would coincide with the lavatory area (and starboard or port side skins are probably similar in a 'stock' airplane).

Jeff,

The best rivet detail I found in the Purdue collection for your aft region of interest was in this
port side shot (first-world-flight configuration).

Chuck
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Jeff Victor Hayden

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #28 on: June 09, 2012, 03:01:25 PM »

"Whilst pure aluminium has low specific gravity, good corrosion resistance and excellent thermal and electrical conductivity it is too weak and ductile to be used on its own. In 1906 Dr Alfred Wilma, a German metallurgist, discovered that aluminium alloyed with copper and heat treated correctly could be made far stronger. The alloy of aluminium with 4% copper is called Duralumin and the heat treatment process is called precipitation hardening. These alloys have typically low specific gravity (around 2.7) and high strength (450 MPa). They are limited by a maximum service temperature of about 660°C. Since then, other heat treatable aluminium alloys have been developed for aircraft use. These include a range of complex aluminium-zinc alloys which develop the highest strength of any aluminium alloy. These alloys have led to modern aircraft design where the skin of the fuselage and wings are stressed aluminium alloy members which reduces the overall weight.
The aluminium alloys mentioned above have the disadvantage of not being as corrosion resistant as pure aluminium so a thin layer of pure aluminium is often pressure welded to both sides of the alloy. This material is called Alclad."


http://hsc.csu.edu.au/engineering_studies/focus/aero/2580/aluminium_alloys.html


Alclad is a trademark of Alcoa used as a generic term to describe corrosion resistant aluminium sheet formed from high-purity aluminium surface layers metallurgically bonded to high strength aluminium alloy core material. These sheets are commonly used by the aircraft industry.[1] The first aircraft to be constructed from Alclad was the all-metal Navy airship ZMC-2, constructed in 1927 at Naval Air Station Grosse Ile.[2]
 
"Described in NACA-TN-259,[3] of August 1927, as "a new corrosion resistant aluminum product which is markedly superior to the present strong alloys. Its use should result in greatly increased life of a structural part. Alclad is a heat-treated aluminum, copper, manganese, magnesium alloy that has the corrosion resistance of pure metal at the surface and the strength of the strong alloy underneath. Of particular importance is the thorough character of the union between the alloy and the pure aluminum. Preliminary results of salt spray tests (24 weeks of exposure) show changes in tensile strength and elongation of Alclad 17ST, when any occurred, to be so small as to be well within the limits of experimental error." In applications involving aircraft construction Alclad has proven to have increased resistance to corrosion at the expense of increased weight when compared to sheet aluminum.[4]"
http://en.wikipedia.org/wiki/Alclad

Aluminium alloys have been around for quite some time (1903) and, are still in use today. A good example being Alclad (1927)which comes in varying thickness and flavours and, is still the main choice in Aerospace development. A few exceptions, Titanium being one for mach 2+ applications.
So I wouldn't expect to be able to match this piece to the electra on the basis of the material it is made from.
The 2117 AD rivet has also been around as long as aluminium alloys and Alclad and again, is still available and in use today. So the rivet also could be from any aircraft manufactured from 1927 to this day.
Suffice to say there is an excellent chance that this artifact came from one of the aircraft that went missing in this area of the pacific and, I suspect the only way to confirm that is to match the rivet patterns, size, orientation and quantity to one of them. I'll get started.



This must be the place
 
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JNev

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Re: Artifact 2-2-V-1 - aluminum 'skin'
« Reply #29 on: June 09, 2012, 03:16:46 PM »

Jeff, there's a lot of stills on this link that show the inside of the Electra viewed from outside the fuselage door. You can see the FN's navigation window and, where the other original window should be but isn't. Looks like these images were aquired after the skinning over.

http://www.criticalpast.com/video/65675063657_Amelia-Earhart-Putnam_Fred-Noonan_transatlantic-flight_Fred-Noonan

Wow - thanks Jeff Victor!  Lot's to go through here - excellent.
- Jeff Neville

Former Member 3074R
 
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