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Author Topic: The Question of 2-2-V-1  (Read 841617 times)

Bruce Thomas

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Re: The Question of 2-2-V-1
« Reply #180 on: February 17, 2014, 05:51:22 PM »

Dunno how I missed it.

Ric, if you check your diary for the day I posted my link to that old picture of Norwich City (6/11/2013), you'll recall you were heavily distracted by a certain development.  ;D
LTM,

Bruce
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« Last Edit: February 17, 2014, 09:19:07 PM by Bruce Thomas »
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Jerry Germann

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Re: The Question of 2-2-V-1
« Reply #181 on: February 17, 2014, 06:28:52 PM »


I meant would the remaining tab (with the three 5/32nds rivet holes) that extends accross the keel line on the artifact..
Upon separation from the larger sheet, I am trying to visualize the scenario, that would leave the remaining tab on the artifact in the manner it appears....

See sketch for what I was thinking about the tab. The "tab" fails at 2nd row of rivets because the skin gets more pushed out from the keel there. The rivets farther from the center shear at the first row because the skin is tighter to the keel there. (the rivets and and deformation are exaggerated for clarity) Kind of a sketchy thought and drawing.

Greg,
Is the port side panel lapped over the starboard panel on earhart's electra?   Wouldn't one see some enlongation of the three starboard side 2nd row rivet holes that remain, ( caused by rivet shank) and possibly see the tab bent in a more upward position...of course after being scavaged it may have been bent back to it's original position, however it seems all other bends on the panel remain. Again it is assumed that the rivet heads popped off upon separation, this would include the larger 5/32nds as well?
« Last Edit: February 17, 2014, 06:35:28 PM by Jerry Germann »
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #182 on: February 17, 2014, 07:44:22 PM »

I don't think the edge with the larger rivets failed at the same time or in the same way as the two fractured edges. I think I know why the tab is not bent up.  I think that edge failed before any of the other edges and from an entirely different type of force.
Note the odd scalloped pattern - the little wave shapes between the torn rivet holes. Have you  ever seen that pattern in any other wreck? I have, but only once. I can show you that exact pattern of failure where two skins were lapped and stitched with a double row of rivets, and it's very apparent why it failed the way it did.
I'll put up a posting with photos tomorrow.

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Greg Daspit

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Re: The Question of 2-2-V-1
« Reply #183 on: February 18, 2014, 10:43:13 AM »





Greg,
Is the port side panel lapped over the starboard panel on earhart's electra?
From looking at the picture of another Electra I think so. See sketch for my understanding to date (which may be wrong)
3971R
 
« Last Edit: February 18, 2014, 01:38:06 PM by Greg Daspit »
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Jerry Germann

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Re: The Question of 2-2-V-1
« Reply #184 on: February 18, 2014, 12:40:58 PM »


Greg,
Is the port side panel lapped over the starboard panel on earhart's electra?
[/quote]
From looking at pictures I thinks so. See sketch for my understanding to date (which may be wrong)
[/quote]

Maybe this topic was covered, however; what was the original thickness of the skin in the artifacts purported position?, ( I thought someone mentioned 0.40 here ). If the port side wasn't replaced, would the procedure be to match the thickness of the adjoining overlapping/underlapping panel? As earhart's plane was repaired at Lockheed, one would assume original thickness material would be readily available.
« Last Edit: February 18, 2014, 12:49:23 PM by Jerry Germann »
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Martin X. Moleski, SJ

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Re: The Question of 2-2-V-1
« Reply #185 on: February 18, 2014, 01:14:38 PM »

Maybe this topic was covered, however; what was the original thickness of the skin in the artifacts purported position?

Um, the whole excitement about 2-2-V-1 began with the recognition that the original thickness of the material and the size of the rivets matched the original thickness and size of the skin in that area.  Ric explained this in the fourth post in this thread.

Before we wander off further into fantasy about what Lockheed "would have done," let me note further that the artifact is made out of the kind of Alclad that was used by Lockheed in repairing aircraft.  "Complete examples of this same size and style of lettering (ALCLAD 24S T3) have been noted on aluminum used in repairs or modifications to two surviving Lockheed 10s: c/n 1015, recently rebuilt as a replica of Earhart’s aircraft and currently registered NX72GT, and c/n 1052 in the New England Air Museum collection" ("[L10] Aircraft Skin").

LTM,

           Marty
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Walter Runck

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Re: The Question of 2-2-V-1
« Reply #186 on: February 18, 2014, 01:57:13 PM »


Note the odd scalloped pattern - the little wave shapes between the torn rivet holes. Have you  ever seen that pattern in any other wreck? I have, but only once. I can show you that exact pattern of failure where two skins were lapped and stitched with a double row of rivets, and it's very apparent why it failed the way it did.


It looks like a tensile failure within the sheet.  Specifically, it looks like the keel was fixed (in the stationary, not repaired, sense) and that the sheet was pulled laterally away from it (to starboard).  The fracture started at the front and travelled from a rivet hole back into the piece until it hit another hole or the perpendicular stresses exceeded the parallel ones and the fracture line changed direction accordingly, zigging back outward in the direction of the pull. 

Try pulling a piece of newsprint apart (top half from bottom half).  I bet you'll get some tears that are nearly right angled at the tip, similar to the sawtooth pattern at the back of the artifact.  Very different from the fatigue-looking (piecewise linear) failures on the forward and aft edges.

Given a certain combination of aircraft position, surf conditions and timing, a wave coming through an open door and impacting the interior of section 269 might load that area in such a way as to produce high tensile loads in the skin.  Enough to yank it away from the double row of #5 rivets that should have been there holding it to the keel?  Maybe.

There should have been additional material both forward and aft of the artifact for it to have reached the formers where it would have been attached.  The stringers in this area seem to have passed through the formers intact, so the repair skin might have extended forward to the next former, but the skin went to .025 thickness (as built) aft of 293, so if the repair matched the existing construction, there would only have been a couple inches of new skin aft of the tear.

Perhaps that section of the airframe was split in half early on and the artifact was then beaten out of the remains of the starboard side over time.  That gives you a tensile fracture on the keel edge and fatigue on the remainder. 

I'm still skeptical about the heads being blown off the #3 rivets without distorting the holes, but I'm more skeptical about someone removing the rivets afterward without more evidence of tool scratches or other damage.  The first one is easy to test, the second is akin to proving a negative.
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Greg Daspit

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Re: The Question of 2-2-V-1
« Reply #187 on: February 18, 2014, 03:19:46 PM »

The NTSB Report referenced did note that “the fracture geometry along the line of 5/32 rivet holes is consistent with tearing separations in both directions away from the area of the intact holes” But why are there “ 3 undamaged holes in the tab” along the same line where these forces caused tearing at the other holes? Interested to see the pictures of something similar. The odd things sometimes turn into the best clues
3971R
 
« Last Edit: February 18, 2014, 03:26:38 PM by Greg Daspit »
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #188 on: February 18, 2014, 05:55:22 PM »

You guys are really sharp. I'm impressed. Here are the photos I promised.

On May 7, 1942  New Zealand Union Airways Lockheed 10A ZK-AFE, in cloud on a routine flight from Wellington to Nelson, struck a nearly vertical rock face on Mount Richmond at the 5,100 foot level. The pilot, copilot, and three passengers died on impact.
In 2004, New Zealand TIGHAR member Howard Alldred chartered a helicopter and visited the remote and relatively untouched crash site.  Howard made an extensive photographic record of the wreckage.  One of his photos shows the upper surface of the right wing outboard of the engine (faint remnants of the last two letters of the registration number are still visible). 
During the crash, the inverted right wing apparently glanced off a rock (the scar of the impact is clearly evident) causing a tear along a double row of rivets where two skins overlap.  The similarity to the tear on 2-2-V-1 is obvious.   
So to get this kind of failure you need to impart a powerful lateral force 90° to the rivet line.  The only way I can think of for that to happen along the keel is if the airplane is on its belly and being driven forcefully sideways across a hard surface.  If the belly tears open in one area and that area is later subjected to breaking waves, the weakened skin (no longer supported along the keel) could fracture.
I think the failure pattern on 2-2-V-1 fits the independently derived hypothesis for what happened to the airplane on the reef to an uncanny degree. But that's just me.


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Greg Daspit

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Re: The Question of 2-2-V-1
« Reply #189 on: February 18, 2014, 06:26:53 PM »

So the plane is being pushed to starboard, and the overlap of the port panel snags and pulls up at the 3 rivets over what will be the tab? Maybe just before the main tearing at the double row edge?
3971R
 
« Last Edit: February 18, 2014, 07:07:59 PM by Greg Daspit »
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #190 on: February 18, 2014, 08:03:32 PM »

So the plane is being pushed to starboard, and the overlap of the port panel snags and pulls up at the 3 rivets over what will be the tab? Maybe just before the main tearing at the double row edge?

Possibly. This piece of metal is telling us a story. We just need to be sure we're hearing it right.
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Greg Daspit

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Re: The Question of 2-2-V-1
« Reply #191 on: February 18, 2014, 08:53:36 PM »

"tearing separations in both directions away from the area of the intact holes" points to the tearing starting in the area of the tab and working out from there.. Seems to fit the plane sliding on the reef sideways and a spur catching the keel area at or near the tab. The same spur possibly pops off a few of the 1st row rivets so those 3 tab holes were undamaged.
The corrosion opposite the tab is interesting but it originated from the inside. Don't know if that tells us anything. It might say more if it originated on the outside. Possibly being due to its protective layer getting scratched off.
Another thought is a water blast thru a hole now in the belly could pop out a floor board.

Recently I tried to scrape off some old hard linoleum glue and it's amazing how much force can be directed up from a thin scraper edge hitting something not movable. I'm thinking that exposed edge at the port panel could direct a lot of force down the panel if it hit even an 1/8" high ledge
3971R
 
« Last Edit: February 19, 2014, 12:02:32 PM by Greg Daspit »
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Jerry Germann

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Re: The Question of 2-2-V-1
« Reply #192 on: February 18, 2014, 09:53:01 PM »

 
[?] Aluminum Comb (TIGHAR Artifact 2-2-V-5) 
Date Found:
Materials analysis:
Report date:
 October 1991 during TIGHAR’s NIKU II expedition.
NTSB
March 5, 1990
 
Description: The comb is crudely formed with parallel saw cuts separating the teeth. It is 3 and 7/8 inches long by 1 and 3/8 inches wide and is made from 0.032 Alclad sheet. Three 3/32 inch diameter holes are nominally spaced 1 and 7/8 inches apart.  Condition: Although broken, the comb exhibits little or no damage from corrosion. 
Commentary: The fashioning of such combs from aircraft aluminum was not uncommon in post-war Polynesia. Combs are specifically mentioned in the one account we have of the local use made of the crash at Sydney Island. When shown a photograph of this artifact, a former resident of Nikumaroro attributed it to the Sydney crash. Nowhere on a Lockheed 10 are #3 rivets found spaced 1 7/8 inches apart in 0.032 skin. 


Is this artifact of the same exact material we are seeing on artifact 2-2-V-1, .. it has been ruled out as a piece of the electra.. (in the past).... do we re-examine it?...if still dis-regarded as an electra piece where ( if not from Sydney) and from what plane did this 0.032 alclad come from?
« Last Edit: February 18, 2014, 10:32:58 PM by Jerry Germann »
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Ric Gillespie

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Re: The Question of 2-2-V-1
« Reply #193 on: February 19, 2014, 05:58:58 AM »

Is this artifact of the same exact material we are seeing on artifact 2-2-V-1,

Yes, but virtually all American all-metal aircraft in the WWII period were made of that material.

.. it has been ruled out as a piece of the electra.. (in the past).... do we re-examine it?

Always willing to re-examine any artifact if there is reason to suspect there is more to learn.

...if still dis-regarded as an electra piece where ( if not from Sydney) and from what plane did this 0.032 alclad come from?

How would you propose to find out?  .032 ALCLAD is ubiquitous, as are #3 size rivet holes. The long pitch suggests non-load bearing structure.  We have no idea what style of rivet was originally in the piece.  What could we possibly learn that would be of benefit?
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Greg Daspit

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Re: The Question of 2-2-V-1
« Reply #194 on: February 19, 2014, 08:40:51 AM »

Illustrations have shown a portion of the port side receiving new skin
I can’t find a copy of the Lockheed repair report. Only references to it.  Can someone direct me to it?
3971R
 
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