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Author Topic: Grand Rapids trip (2-2-V-1)  (Read 132549 times)

JNev

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Re: Grand Rapids trip
« Reply #120 on: February 03, 2014, 01:12:35 PM »

'Intermediate' = 3/32" (not 3/16"?) lines lying well within sheet boundaries in my meaning.  My thought has been that those may be a crap-shoot - not necessarily patterned after existing holes on Electra, whereas those along the edge might coincide with something we could identify as an original pattern on the Electra.

Yes, 3/32".  My bad. 
From the NTSB report: "The remains of a solid brazier-head rivet were found in the hole denoted by arrow "R" in
figure 1. The manufactured head of the rivet was on the convex side of
the sheet and was marked with a single round dimple in the center of the
head, as shown in the right center photograph of figure 1. The dimple
usually signifies a 2117 aluminum alloy rivet. The length of the
undeformed rivet shank (distance between the manufactured head and the
formed head) indicated that the skin had previously been attached to an
approximately 0.06 inch thick underlying member."

In other words, those "intermediate" rivet holes indicate the former presence of underlying members, presumably stringers.

Good stuff - and .060" is substantial thickness for an 'underlying member' - which could easily be an underlying skin and stringer flange combined.  That suggests an external doubler to me rather than a replacement skin - one that would pick-up all thicknesses underlying the outer doubler. 

That would not be unheard of where a rapid repair scheme was employed - not the neatest approach (in essence a large 'scab patch') but effective enough if  the area had relatively mild damage and a quick reinforcement was decided upon in lieu of a more complex removal / replacement.  The use of such small rivets (in the 'intermediate' rows) is odd - the expected norm would be 1/8" or larger diameter - but again, in a rapid repair situation this could certainly happen.  in the context of so many things we know about Earhart and Putnam, their priorities (and lack of on certain things) and that it is not a perfect world, that kind of stuff can easily happen.
 
Perhaps a breakthrough will come for the belly or elsewhere yet - this 'skin' is still a great find as I see it.

Quote
The breakthrough has already broken through. All aspects of the artifact, including the rivet pattern, fit closely with a section of the belly on the right hand side of the aircraft between stations 269 5/8ths and 293 5/8ths.  The apparent discrepancy in the spacing between stringers may be due to distortion due to the deformation of the fragment of skin when it blew out of the belly.  The one known discrepancy between the rivet holes in the artifact and standard Electra construction is the line of 5/32" holes along the one edge.  The standard airplane has a double row of staggered 3/32" rivets along the keel where the skins overlap.  The artifact shows evidence of a double row of staggered 5/32 rivets.  Aris Scarla sees the use of larger rivets along the keel in the repair as a reasonable possibility in the repair of NR16020.

I'm surprised that the original stock keel skin lap joint had 3/32" rivets - if that is accurate then it reveals something that might be even more supportive.  I'd double-check that figure - surprised to hear of rivets smaller than the typical 'no smaller than' no. 4 (1/8") rivets commonly expected for primary structure.  Nonetheless, 5/32" may be the rational 'next size' replacement so common where repairs are concerned.

The distortion is significant looking - that outboard row / edge diverts noticeably from the standard stringer location.  But we don't know for certain that N16020 did not have a mod in that local area for some reason - there was a nav station in that area of the floor and there could have been a sub-floor alteration to accomodate some installation we don't know anything about yet.  And as you've pointed out, the destructive force of whatever took that member out of the parent structure could well have imparted some degree of stretching or distortion as well.  That is a lot for heat-treated dural to endure without splitting, but between that possibility and that of a modified structure it could easily be.

Very interesting, and a picture is a worth many words.  I appreciate Mr. Scarla's comments on the matter - I'm sure he's seen many real-world repair and alteration schemes and knows his analysis well.
- Jeff Neville

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Friend Weller

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Re: Grand Rapids trip
« Reply #121 on: February 03, 2014, 01:26:56 PM »

A thought:  what if the artifact was not "blown out" by hydraulic forces or wave action?  Since it corresponds closely with the floor section opposite the cabin door, what would be the possibility that as NR16020 was going over the reef edge that the airframe crumpled/buckled on the door side, this being a "weaker" point compared to other more continuous portions of the fuselage (no "large" openings), causing the skin on the starboard side of the aircraft to "expand", stretching and tearing free?  As the artifact appears to be from closer to the "keel" of the airframe, this might result in less deformation of the artifact compared to a location higher up on the side of the fuselage where more drastic tearing would take place (starboard) or crumpling/buckling (port).  I can envision that if the aircraft were to buckle laterally at this station, the floor skin could be torn and popped out from it's installed position.  Not being an airframe engineer but having worked closely on a small all-aluminum airplane project years ago, my experience causes me wonder if this area of the Electra was not particularly resistant to side-to-side forces but designed more for vertical loads and moments between the wing and the empennage.    Just a thought.....

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Ted G Campbell

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Re: Grand Rapids trip
« Reply #122 on: February 03, 2014, 02:57:15 PM »

Ric,

If one would lay a thin layer of Mylar over the inside and outside of 2-2-V-1 – matching the bulge (deformation) as best as one can – then cut the Mylar along the edges to trace the outline of 2-2-V-1 could we then see how the flatten template might match the original skin?  I guess where this template might deviate from the original skin is if 2-2-V-1 underwent stretching and thinning significantly in the bulged area.  Low cost exercise I would think.

Ted Campbell
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Ric Gillespie

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Re: Grand Rapids trip
« Reply #123 on: February 03, 2014, 03:33:27 PM »

If one would lay a thin layer of Mylar over the inside and outside of 2-2-V-1 – matching the bulge (deformation) as best as one can – then cut the Mylar along the edges to trace the outline of 2-2-V-1 could we then see how the flatten template might match the original skin?  I guess where this template might deviate from the original skin is if 2-2-V-1 underwent stretching and thinning significantly in the bulged area.  Low cost exercise I would think.

That has been done and it is that exercise that seems to have resulted in the distorted impression that caused us to see discrepancies that might not be there.  It turns out to be a very tricky thing to take a piece of deformed wreckage and determine it's exact dimensions and features when it was undamaged.  Aris Scarla assures me there are ways to do it.  I await his advice and  assistance.
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Friend Weller

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Re: Grand Rapids trip
« Reply #124 on: February 03, 2014, 09:49:45 PM »

After taking another look at the overlay photo of the artifact and the Harney drawings on the site, I noticed the proximity of the aft ventral antenna mast to the area of the the artifact.  If we accept the theory of the loss of the antenna upon takeoff from Lae, would it be reasonable to postulate that during the loss of the mast, the underside of the aircraft in the vicinity of the artifact may have been damaged just enough to crack stiffeners or pop rivets creating a weakened area?  This could have been either from the sudden forcing upward and aft of the mast upon contact with the ground surface while taxiing or the hammering of the underside of the aircraft as the mast bounced along during the takeoff roll prior to the antenna separating from the plane.  If enough rivets were popped from the deformation of the skin and stiffeners, this may have resulted in 20+ hours of "oil-canning" during the flight or perhaps severe weakening during the landing fatiguing the skin in that area making it easier for it to fracture/tear/pop when NR16020 went over the reef edge.

Random thoughts?   Cabin fever?  If this scenario has been discussed and decided before, my apologies!
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Walter Runck

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Re: Grand Rapids trip
« Reply #125 on: February 03, 2014, 10:55:26 PM »

It turns out to be a very tricky thing to take a piece of deformed wreckage and determine it's exact dimensions and features when it was undamaged.  Aris Scarla assures me there are ways to do it.  I await his advice and  assistance.

There is design software that does exactly that with sheet metal.  You create a model of the end product and then it figures out where the bends would have to be placed to get that result.  One of the outputs is the flattened shape that you would need to start with to make the (de)formed part.

It works very well for things with clean features like straight lines and right angles.  The difficulty with more complex shapes comes in the fidelity of the model.  You can either build a math model and try to create the shape using geometric building blocks or run the part through a 3D scanner and work with a numerically defined shape model.

I expect there are versions of software customized for forensic work that I don't have access to, but the  standard stuff might provide at least a rough answer.  It would, however, require a higher level of measurement fidelity than I have seen for this part.
« Last Edit: February 04, 2014, 05:36:40 AM by Walter Runck »
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Greg Daspit

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Re: Grand Rapids trip
« Reply #126 on: February 04, 2014, 02:21:29 PM »

The scratches/ suggestive pry marks noted in the initial summary of 2-2-V-1 and how this aircraft skin was found tangled with the antenna lead are a puzzle to me. The possible pry marks suggest salvage but the tangled wire and good condition of the aluminum do suggest wash up and temporary cover by sand. It could be the aircraft skin was salvaged and abandoned.
Also a tear on one side of 2-2-V-1 being folded in, not out. (I think I am seeing that right?) Could the popped rivets, the fold-in and the pry marks be part of a process including isolated wave force, fuselage break-up and then salvage?
Also why the Bevington object stayed on the reef and the little wheels I see in the debris field could all be related to the fisherman John Mims saw and control cable. This fisherman could have cut the control cable holding the landing gear and other stuff on the reef and salvaged the 2-2-V-1 aircraft skin. Some of the other control cable may have held a pulley to the wing edge and continued down the reef slope possibly seen in the debris field.
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« Last Edit: February 04, 2014, 02:51:34 PM by Greg Daspit »
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Jerry Germann

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Re: Grand Rapids trip
« Reply #127 on: February 04, 2014, 03:02:27 PM »

The scratches/ suggestive pry marks noted in the initial summary of 2-2-V-1 and how this aircraft skin was found tangled with the antenna lead are a puzzle to me. The possible pry marks suggest salvage

Question; ....is it still the concensus that the scratch marks noted on the panel when initially found, were the result of the use of a prying tool ? If so, wouldn't that indicate that either ( stringers/supports) or parts thereof were attached to this panel before said prying action.... becoming separated later by this prying means? If that is true, then what force /action would separate not only this panel from the larger sheet, but possibly detach one or more supports along with it as well? 
Also, may this artifact have been repurposed, and the resulting damage sustained then? 
« Last Edit: February 04, 2014, 04:32:13 PM by Jerry Germann »
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Ric Gillespie

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Re: Grand Rapids trip
« Reply #128 on: February 04, 2014, 06:31:23 PM »

Question; ....is it still the concensus that the scratch marks noted on the panel when initially found, were the result of the use of a prying tool ?

Yes.

If so, wouldn't that indicate that either ( stringers/supports) or parts thereof were attached to this panel before said prying action.... becoming separated later by this prying means?

Yep.

If that is true, then what force /action would separate not only this panel from the larger sheet, but possibly detach one or more supports along with it as well?

Breaking waves.
 
Also, may this artifact have been repurposed, and the resulting damage sustained then?

The sheet may very well have been repurposed but after it sustained the damage. The fragment of sheet seems to have separated from the aircraft with pieces of stringers still attached (only a few of the rivet holes show evidence of prying).  The sheet later washed up and was found by a local who saw its potential usefulness as a griddle for cooking.  The local pried off the surviving pieces of stringer.  This hypothesis is supported by ALCOA's finding that portions of the sheet have lost ductility due to being heated and anecdotal accounts from former Nikumaroro residents who describe just such a piece of aluminum with rivet holes being used to cook fish.
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JNev

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Re: Grand Rapids trip
« Reply #129 on: February 05, 2014, 12:26:27 PM »

I need to share that this artifact has created a major tipping point in my view of the Niku landing hypothesis -

In my opinion as an A and P Mechanic / IA of some 36+ years - 33 of those in various roles at a major airframer including maintenance, repair, inspection and engineering, I find this surprisingly complex artifact to be  compelling: this skin truly could have originated from the belly repairs done to NR16020 prior to the world flight.  In fact, it represents such a unique slice of potential that to me it cannot be just "anything": too much is now realized about the character of this item and where it lies in the aviation timeline for material, construction practices and the circumstances of the belly repairs done on NR16020 to ignore the potential. 

Couple that with the strong context of so many other things shared here - including other 'odd' things like plexiglass matching in thickness and contour to that of L10 Lockheed windows and the case only gets stronger. 

The Lockheed L10 has proven herself a stand-out in yet another new way to this old mechanic: her belly skins do include a large number of no. 3 rivets as primary strucural fasteners.  This had been a hard sticking point with me for some time and threw me into the "could be anything" camp for quite some time.  Now I realize the first all-metal transport used some arcane features as it pioneered so much taken for granted today - the Lockheed engineers mastered the reduction of material to build a light but durable stressed-skin bird before the onset of later guidance that tended toward heavier building practices.  I now believe we are seeing an example of repair to none other than one such craft.  I also know of only one such example that would have borne such light work in that part of the world. 

Are there other possibilities?  Of course - but a time has come for me to seriously suggest that they are very limited indeed: AN 455 brazier rivets of no. 3 size coinciding with a similar feature in the L10 is not so common, nor are the pre-war markings we find on this sheet.

One realizes that this sheet of ruined metal 'could be anything' to many eyes and minds - but training, experience and now observation and acceptance of some hard data make this complex item very pointed in its meaning.  The scales have tipped IMO - if there is a better explanation as to where this came from given the web of circumstantial (but substantial to this writer) evidence we have - including plexiglass of correct curvature and thickness, etc. - I would respectfully ask the challenger to provide evidence of it.

This is of course my humble opinion, but I suggest the skeptic study and look hard if they'd offer a better idea of what became of the flight.  As to where found and how it got there - a worthy consideration, consider what now appears to be strong provenance as to this part: if it came from the Electra, but not at Niku - then where else?

I merely (but now strongly) suggest that there is not a wealth of other possibilities.  The reader must of course draw his own conclusions.  But mine, after quite a journey, is that somehow a unique piece of aviation repair history managed to beach itself on the shores of Niku - among other nested things that support the circumstance of a stranded L10E belonging to Amelia Earhart.

This is my own opinion - others may of course play the odds as they will, but I submit that TIGHAR's pain-staking efforts have produced plausible material that reaches beyond reasonable doubt. 

This is reason itself for me after a long journey - I can think of no better notion of where this piece of history came from given all we know to-date - and now what I discern in this part is just too specific to ignore.  The full context as underpinned by the specifics of this part and others like the plexiglass tells me that Earhart found Gardner in 1937.

Hats off to all those who care about and search for the lost aviators, whether they agree or not - may they always be reasoned and reasonable in their arguments.  TIGHAR's reasoning after much labor tips the case strongly to Niku IMO - I respect that a great deal.  It is my hope that further searching will produce the airplane, but short of that and barring something more weighty than we have here (not expected, frankly), the circumstances of what has been found point to Gardner as host to a certain famous L10E in 1937.  Thanks to Ric and TIGHAR for the vision of it, and the hard work to reveal all that can be found to prove it.
- Jeff Neville

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« Last Edit: February 06, 2014, 07:44:48 AM by Jeffrey Neville »
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Jerry Germann

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Re: Grand Rapids trip
« Reply #130 on: February 09, 2014, 12:41:59 PM »

Aris Scarla, Bob Brandenburg and I are designing an experiment to confirm how much and what kind of force is needed to cause the damage we see on the artifact.  Aris can build a reproduction of the belly of the Electra in the area where we think the failure occurred. The same aluminum sheet and stringers are commonly available today but finding the old-style brazier head rivets might be tricky.  Bob can calculate the required force.  We'll need to partner with a university or research facility that has the capability to generate the kind of fluid force we need.

Knowing what it takes to cause this kind of damage will tell us a great deal about what circumstances the aircraft the artifact came from must have experienced. That, in turn, should enable us to refine our hypothesis of what happened to NR16020 and how much of it is likely to be left to find.
Was wondering how this experiment was progressing, and in doing this procedure , does one perform this test with a replica of the wooden floor walkway panel in place above this area? Further,.. if this panel fits this area of the underbelly, (and we assume the area aft of this location was detached from the rest of the plane),... would the remaining length of the surviving nose to suggested separation point of the structure duplicate the anomaly's size?
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Tim Mellon

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Re: Grand Rapids trip
« Reply #131 on: February 09, 2014, 02:05:50 PM »


Further,.. if this panel fits this area of the underbelly, (and we assume the area aft of this location was detached from the rest of the plane),... would the remaining length of the surviving nose to suggested separation point of the structure duplicate the anomaly's size?

It very well might, Jerry, but since the entire center section of the fuselage (aft of the main beam back to the lavatory) lies elsewhere at a depth of 1046 feet, the coincidence would hardly matter.
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Ric Gillespie

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Re: Grand Rapids trip
« Reply #132 on: February 09, 2014, 04:03:43 PM »

Was wondering how this experiment was progressing, and in doing this procedure , does one perform this test with a replica of the wooden floor walkway panel in place above this area? Further,.. if this panel fits this area of the underbelly, (and we assume the area aft of this location was detached from the rest of the plane),... would the remaining length of the surviving nose to suggested separation point of the structure duplicate the anomaly's size?

We're not making any assumptions at this point and we're still discussing the design of the experiment - and it's waaaay too early to worry about how all this might fit with the anomaly.  The first step is to confirm that the artifact is from NR16020.  If it's not then we don't much care how it got the way it is.
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Tim Mellon

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Re: Grand Rapids trip
« Reply #133 on: February 09, 2014, 06:15:29 PM »

Ric, a suggestion:

If you ever get back to Niku with an ROV, why don't you dive down 1046 feet and see if the 2-2-V-1 artifact is actually missing from the bottom of the fuselage near the main entry door.

As to why it became detached, why not take the advice of your colleague, the former Secretary of State, Hillary R. Clinton:

               "What difference does it make?"

Tim
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« Last Edit: February 09, 2014, 06:22:33 PM by Tim Mellon »
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Tim Mellon

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Re: Grand Rapids trip
« Reply #134 on: February 09, 2014, 06:35:04 PM »

Oh, here is a capture of the Main Beam from the 2012 Standard Definition Video showing the cutouts in comparison to a photograph of the construction of the Electra.


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