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Author Topic: The Question of 2-2-V-1  (Read 634430 times)

Ric Gillespie

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The Question of 2-2-V-1
« on: February 03, 2014, 09:54:26 AM »

Here's the question:  What evidence would you need to see to convince you that Artifact 2-2-V-1 came from NR16020?

Let's see if we can define the hurdles that must be cleared and what it would take to establish that each has been cleared.  Maybe we'll find a hurdle that absolutely disqualifies the artifact. Maybe not.  If we clear all the hurdles does that make it smoking gun?

We already know that this artifact is more promising than we previously realized. How good is it?  Let's find out.

« Last Edit: February 03, 2014, 11:41:00 AM by Ric Gillespie »
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JNev

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Re: The Question of 2-2-V-1
« Reply #1 on: February 03, 2014, 10:25:18 AM »

Here's the question:  What evidence would you need to see to convince you that Artifact 2-2-V-1 (pictured below) came from NR16020?

Let's see if we can define the hurdles that must be cleared and what it would take to establish that each has been cleared.  Maybe we'll find a hurdle that absolutely disqualifies the artifact. Maybe not.  If we clear all the hurdles does that make it smoking gun?

We already know that this artifact is more promising than we previously realized. How good is it?  Let's find out.

As tantalizing as it is, 'circumstantial' is weak on this one due to other non-Electra associated airplane stuff found there which implies to me that there was importation of 'junk' by some method among the islanders.  For that reason, for me (since you asked) we have to find a way to tie this part directly to the Electra. 

If this part is a smoking gun, the bullet must lie somewhere among the Electra's repair history (it's almost certainly not a production part UNLESS the oddball intermediate rows (those smaller rivet holes in the middle of the sheet, not at edges) have to do with some added component perhaps).  How the part failed is interesting and perhaps telling to some degree, i.e. consistency with a stranded bird being pounded in surf, etc. but the definitive golden smoking gun is tying it to N16020 via photographic or written repair/inspection record.

Just MHO.  Glad to see the focus on this one and thanks for asking.
- Jeff Neville

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Walter Runck

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Re: The Question of 2-2-V-1
« Reply #2 on: February 03, 2014, 10:29:08 AM »

Rivet pattern match with contemporary photo or engineering documentation.  We already know that it came from a plane, we just need to show where it got its defining characteristics.

Or, find the rest of the plane and see if this piece is missing!
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Albert Durrell

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Re: The Question of 2-2-V-1
« Reply #3 on: February 03, 2014, 11:00:49 AM »

Please forgive my complete ignorance on the topic of material, rivets, corrosion, etc.  One way this might be disproved is to find where the artifact would fit on a different model plane.  I have no idea how many different models may have been flown in this part of the world in that timeframe, but could the part be compared to the more usual planes that flew in that area?  Finding an exact match for something other than the Electra would tend to decrease the chance that it came from her plane.  Too many models?  Too big a job?
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #4 on: February 03, 2014, 11:34:55 AM »

Please forgive my complete ignorance on the topic of material, rivets, corrosion, etc.  One way this might be disproved is to find where the artifact would fit on a different model plane.  I have no idea how many different models may have been flown in this part of the world in that timeframe, but could the part be compared to the more usual planes that flew in that area?  Finding an exact match for something other than the Electra would tend to decrease the chance that it came from her plane.  Too many models?  Too big a job?

Complete ignorance is often a benefit.  We've tried and tried and tried to find somewhere on some other airplane that matches this piece.  So far, no luck.

Disqualifying WWII aircraft may be easier than we thought.  Jeff Neville has already said, "For another thing, #3 rivets have long been considered less-than adequate for primary structure and generally are not used in stressed skin situations (this taught me from early days in A&P school, granted some years after Earhart's time - but a long-standing practice)." And yet the Lockheed Model 10, designed in 1934, does indeed use #3 rivets in .032 stressed skins.  The FAA's Aris Scarla has said, "You just don't see smaller than #4 rivets in WWII airplanes." If we can confirm that no American WWII aircraft that served in or transited through the Central Pacific used #3 rivets in .032 stressed skins, then the artifact had to come from an aircraft that pre-dated the abandonment of that practice.  If that is true then it is easy to list the pre-war aircraft that came anywhere near Gardner Island.  Only one of them had #3 rivets in .032 skin and only one of them was lost, damaged, or disappeared.  Bob's your uncle and the gun smokes.

So - how do we confirm when the practice of using #3 rivets in primary structure was abandoned?
« Last Edit: February 03, 2014, 11:43:09 AM by Ric Gillespie »
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #5 on: February 03, 2014, 11:40:07 AM »

Here's the question:  What evidence would you need to see to convince you that Artifact 2-2-V-1 (pictured below) came from NR16020?

I forgot to post the picture.  Here 'tis.
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Albert Durrell

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Re: The Question of 2-2-V-1
« Reply #6 on: February 03, 2014, 12:59:37 PM »

Someone who can speak rivets may want to contact this company:

http://www.nationalrivet.com/about.htm

Their history starts in the 20's and they did a lot of WW2 work.  They may have some relevant information.

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JNev

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Re: The Question of 2-2-V-1
« Reply #7 on: February 03, 2014, 01:31:42 PM »

Someone who can speak rivets may want to contact this company:

http://www.nationalrivet.com/about.htm

Their history starts in the 20's and they did a lot of WW2 work.  They may have some relevant information.

The company is no doubt a good source of history from the specialized supplier's point of view, but the practice of rivet sizing would lie with the airframer (in this case, Lockheed - unless this part is from another maker).

I am intrigued to learn of the use of #3 rivets in older types more commonly than I had imagined - and that size brazier head rivet was made by the millions for some reason other than to have a few dozen in limited applications per airplane.  The brazier also disappeared for the most part about the time of the war, and universal head (AN470) types showed up.  They also come in 3/32", but as Ric points out, it would be good to pin down the practice of "#4 or larger" and when it began. 

For me it is anecdotal for now - something tattooed on our young heads in A&P school and followed as if catechism by most of us as we went into the world to work.  Few of us had that much contact with pre-war antiques, so I can't claim expertise on something as rare as an L10 Lockheed.  Nor do even museum birds necessarily give us an accurate view - smaller rivets of the past may have been replaced over the decades due to who-knows-what damage, etc.  The drawings would 'know'.

All of this points to Albert's first point to me - can we make a distinction as to what types might be involved so as to consider other sources (and make that a bit more workable by eliminating war machines)?  I trust Mr. Scarla's experience on this - and all the warbirds I am familiar with have a tendency toward 'over-built', i.e. would be surprised to find #3 rivets in primary construction - seriously doubt it exists in the types we'd find lost in that area of the Pacific.  Some research might verify that quickly enough, but for my work I trust this judgment.

So I'd look for pre-war types operating in the region as a possible source and try to elminate from there.  I think that has been done but can't point to the specifics (and admit being pressed for time so as to do myself right now).  Meanwhile we still have a fascinating prospect IMO.
- Jeff Neville

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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #8 on: February 03, 2014, 02:43:16 PM »

So I'd look for pre-war types operating in the region as a possible source and try to elminate from there.

Remember.  To qualify as an alternative source for 2-2-V-1 we need an American pre-war type that used #3 rivets in a .032 ALCLAD skin - and it has to have been repaired and then later destroyed in a way consistent with the damage we see on the artifact.

First, let's list all known pre-war (prior to December 1941) aviation activity at or near Gardner Island. It's a short list.
July 9, 1937 - Three Vought O3U-3 Corsairs launched from USS Colorado. Aircraft not damaged. Not a candidate.
Dec. 1, 1938 - Supermarine Walrus launched from HNNZS Leander took aerial photos for the New Zealand survey. Not an American aircraft. Not damaged. Not a candidate.
April 30, 1939 - Grumman J2F Duck launched from USS Pelican took aerial photos for the Bushnell survey.  Aircraft not damaged. Not a candidate.
June 20, 1941 - Six Consolidated PBY2 aircraft took aerial photos for a strategic survey.  Aircraft not damaged.  Not a candidate.

That's it for pre-war aviation in the region.
During WWII the only pre-war type based at Canton Island were two Douglas B-18s.  No record of what became of them but there is no accident report either.  The B-18 was basically a bomber version of the DC-3.  I've inspected the B-18 in the USAF museum collection.  Big airplane. No #3 rivets.  Not a candidate.

In short, there are no known candidates other than the Lockheed 10 that is known to have been lost in the region.

We need to document when #3 rivets stopped being used for primary structure.

"...the practice of rivet sizing would lie with the airframer (in this case, Lockheed - unless this part is from another maker)."

Wouldn't rivet sizing be governed by Bureau of Air Commerce regs?
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JNev

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Re: The Question of 2-2-V-1
« Reply #9 on: February 03, 2014, 04:00:27 PM »

So I'd look for pre-war types operating in the region as a possible source and try to elminate from there.

Remember.  To qualify as an alternative source for 2-2-V-1 we need an American pre-war type that used #3 rivets in a .032 ALCLAD skin - and it has to have been repaired and then later destroyed in a way consistent with the damage we see on the artifact.

First, let's list all known pre-war (prior to December 1941) aviation activity at or near Gardner Island. It's a short list.
July 9, 1937 - Three Vought O3U-3 Corsairs launched from USS Colorado. Aircraft not damaged. Not a candidate.
Dec. 1, 1938 - Supermarine Walrus launched from HNNZS Leander took aerial photos for the New Zealand survey. Not an American aircraft. Not damaged. Not a candidate.
April 30, 1939 - Grumman J2F Duck launched from USS Pelican took aerial photos for the Bushnell survey.  Aircraft not damaged. Not a candidate.
June 20, 1941 - Six Consolidated PBY2 aircraft took aerial photos for a strategic survey.  Aircraft not damaged.  Not a candidate.

That's it for pre-war aviation in the region.
During WWII the only pre-war type based at Canton Island were two Douglas B-18s.  No record of what became of them but there is no accident report either.  The B-18 was basically a bomber version of the DC-3.  I've inspected the B-18 in the USAF museum collection.  Big airplane. No #3 rivets.  Not a candidate.

In short, there are no known candidates other than the Lockheed 10 that is known to have been lost in the region.

We need to document when #3 rivets stopped being used for primary structure.

"...the practice of rivet sizing would lie with the airframer (in this case, Lockheed - unless this part is from another maker)."

Wouldn't rivet sizing be governed by Bureau of Air Commerce regs?

I thought so and looked at the old Air Commerce guidance and regs, couldn't find a direct reference.  A look at the more modern AC 65-15A (same as 65-15 in this regard but for large airplanes) gives a formula that makes sense (ref: AC 65-15A Section 5, page 128):

"The size of rivets for any repair can be determined by referring to the rivets used by the manufacturer in the next parallel rivet row inboard on the wing, or forward on the fuselage.  Another method of determining the size of rivets to be used is to multiply the thickness of the skin by three and use the next larger size rivet corresponding to that figure.  For example, if the skin thickness is 0.040 in., multiply 0.040 by 3, which equals 0.120; use the next larger size rivet, 1/8 in. (0.125 in.)."

Of course the manufacturer can design as they will, short of an outright rule about this sort of thing.  I don't think that exists - don't know of it, just 'guidance' - which is binding in the absence of other data, and typically consistent with 'best practices'/what is typically done by designers.  What an airframer typically does is meet the overall static strength, damage tolerance, fatigue and aero-elastic qualities, etc. required for structures by employing details that are not, themselves, always directly governed by hard rule.

By the way, the strength of a 2117T 3/32" rivet in single-shear is about 186 pounds per 'Figure 2' on that page as cited above - probably about the same for the old brazier head style.  Tension failure would occur at about 60% of that value (ductile modus) - or at around 111.6 pounds of tension.  If all those let go at once (excluding the 'keel' row of large fasteners for illustration) you are looking at around 7000 pounds of total force to fail all the 3/32" rivets in unison (does not consider the outer rows / larger rivets); if what we're seeing of that panel is around 275 square inches, that would come to around 25 PSI or so.  If that accounted for the fractures we see (are they all brittle failure, or is there evidence of cyclic fatigue failure, i.e. repetitive bending until failure along one or more edges?) then one should add a value for the tensile strength of the skin, not to mention the addtional and larger fasteners.

I can think of a bunch of experiments to screw around with to get an idea of how this thing failed.  It would be interesting to understand more about the apparent 'explosive' evidence of bulging, etc. but it is hard to imagine how even a raging sea would distort that much metal.  I can readily see the sea 'worrying' the piece off after some initial damage, maybe even fastener-by-fastener, and then failing the remaining edge rivets or fracturing the metal to separation.

Anyway, interesting and there are tons of possiblities.
- Jeff Neville

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« Last Edit: February 03, 2014, 04:10:42 PM by Jeffrey Neville »
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Jeff Carter

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Re: The Question of 2-2-V-1
« Reply #10 on: February 03, 2014, 05:47:10 PM »

Anyway, interesting and there are tons of possiblities.

Looks like the Japanese got there hands on some ALCLAD also:  http://www.pacificwrecks.com/douglas/wrecks/mavis/mavis.html


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Bill de Creeft

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Re: The Question of 2-2-V-1
« Reply #11 on: February 03, 2014, 06:38:34 PM »

Ric, Would you remind me of the  location or installation where the repair was done?
It might remind us of the circumstances where and when the repair was done.

I'm thinking if it was at Lae there might be less of a choice for material at hand, and more pressure to 'get a patch on there' and resume the flight...

Even if it was Hawaii...I've seen cases of "lets get this thing going and we'll come up with paperwork later"

(the answer to that is "yeah but the holes drilled in the stringers were pre-existing and the rivets had to fill the holes"...
 No answer to that.)
So we're back to #3 rivets...but the pattern is still open for interpretation.

So on the other existing lockheed wrecks are there just no #3 rivets....or just not in the 'presumed' (dangerous word !?!) position on them ?

I'm of the school that says "yeah, probably from there...soon as we find the airframe we'll prove it; meantime keep looking !!"

Bill
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #12 on: February 03, 2014, 07:04:17 PM »

Anyway, interesting and there are tons of possiblities.

Looks like the Japanese got there hands on some ALCLAD also:  http://www.pacificwrecks.com/douglas/wrecks/mavis/mavis.html

But the rivet is a dimpled American rivet.  and besides, there were no Japanese aircraft lost anywhere near Gardner island.
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #13 on: February 03, 2014, 07:06:05 PM »

Ric, Would you remind me of the  location or installation where the repair was done?

The repairs were done at the Lockheed factory in Burbank and inspected and approved by Bureau of Air Commerce inspectors.
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Martin X. Moleski, SJ

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Re: The Question of 2-2-V-1
« Reply #14 on: February 03, 2014, 07:13:48 PM »

Ric, Would you remind me of the  location or installation where the repair was done?

At Lockheed in Burbank, California.
LTM,

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« Last Edit: February 03, 2014, 08:42:14 PM by Bruce Thomas »
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