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Author Topic: 2-2-V-1 - patch?  (Read 1147773 times)

Diego Vásquez

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Re: 2-2-V-1 - patch?
« Reply #1080 on: December 20, 2014, 11:52:47 PM »

Ric –

There are an awful lot of issues concerning the dimensions of the Miami patch and whether or not 2-2-V-1 can fit within those dimensions.  The 2-2-V-1 thread has already gone 73 pages.  I think that it will take quite a few more pages to resolve the fitment issue.  I would respectfully suggest that you start a new thread, something along the lines of “Miami Patch Dimensions” and transfer our last few exchanges to that thread.


On another note, I couldn’t help but notice, even before of Jeff’s recent post, that you previously chastised him severely for forgetting to add in additional skin to allow for the 2-2-V-1 to have been riveted to something: 

Did I say anything contrary to what it should have told me?

You said, " I can see what looks very much like a tell-tale rivet line up near where could be the window edge - which makes me wonder if there was an added angle at the top of the window frame, which could explain the now-surviving 'upper' rivet row we see on 2-2-V-1 (perhaps there was another higher up prior to the part being separated from mother)."

You seem to be wondering about things that have already been established.  That tell-tale rivet line has been confirmed.  The edge above that line is not a finished edge so there had to be additional skin above that line and it had to be riveted to something [emphasis added].

Did you make the same minor error when making your calculations that suggested you had a half an inch to spare?  If so, could you please redo your calculations to allow for the fore and aft rivet lines that at one time must have been part of 2-2-V-1 (if indeed it were part of the Miami patch) and let me know what you come up with.  Thank you.

Diego
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Diego V.
 
« Last Edit: December 21, 2014, 12:20:47 AM by Diego Vásquez »
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JNev

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Re: 2-2-V-1 - patch?
« Reply #1081 on: December 21, 2014, 09:15:19 AM »

Ric,

Again, thanks for your thoughtful reply on this.  I appreciate the continuing emphasis on Glickman's work toward interpretation of the photo data.  I think there is value, however, in a more direct review of the Wichita exercise, given -

...I agree that the forward edge of certainly the window coaming and apparently the subsequent patch were set back from Station 293 5/8.  Based on the known 1.5 inch rivet pitch on the skin forward of the window/patch, the window coaming looks to have been riveted about an inch and a half aft of the edge of the skin.

I agree and was able to validate it by scaling landmarks on the very clear Wichita picture against similar landmarks on the Earhart Electra in the Nilla-Amelia picture, namely the rivet row at STA 320, and distance to the aft edge of the skin near STA 293 5/8.  I used the direct measurements available in the form of your measuring tape on the Wichita image as a starting point by which to establish some actual datum references - rivet line and skin edge displacements, namely.

By direct measurement thus it is 12" from the rivet line at STA 307 to the aft edge of the skin near STA 293 5/8 - see picture.  The forward coaming vertical rivet line lies approximately 1.5" aft of the aft edge of the skin ending near STA 293 5/8.  The forward coaming rivet line - and assuming the patch is similar - as it does appear to be, lies therefore 10.5" forward of the rivet line at STA 307. 

See attached mark-up of your Wichita photo and reference the scale you and Glickman applied thereon, please.

...we can place the forward edge of the patch at 295 1/8.

This citation of a station may be an indicator of an assumption that has introduced error - there can be a hazard in using assumptions about rivet lines lying faithfully along stations.  Deriving distances this way may have swayed your calculations. 

Visible rivet lines and skin edges can be and often are actually offset from 'stations', which are in fact more theoretical at times than easily pinpointed physical landmarks.  A station more often is one face or the other of a bulkhead, etc. as laid-up in the jig, but seldom directly in alignment with a rivet line.  A study of the Wichita photo, with the measureable scaling you provided there, shows this to be the case on the Lockheed, in fact. 

Therefore I submit that a direct observation of the tape measure in your Wichita photo is the more reliable method: I get 23" from the forward coaming / patch rivet row, as we've assumed it to be placed, to the rivet row at STA 320, if that was used as you've assumed for this exercise.  Please again see attached.

...So the horizontal dimension of the patch would be 24 7/8 (320 minus 295 1/8).

This is what I just described - it does not appear to be a good way to derive this distance.  Consider what you can observe against the tape measure in the Wichita photo instead and forget 'stations' for a moment - see if you get closer to 23" from the forward coaming / patch rivet line to the rivet line at (or near) STA 320 by actual measurement as I did.

The horizontal length of the artifact is 24 3/8 so the artifact fits within the horizontal dimension of the patch with half an inch to spare - assuming all of our assumptions are correct.

I think those assumptions are measurably off for reasons cited.  It appears now to me, that the horizontal dimension of the patch, if STA 320 was picked up and if the forward row of rivets is as we've believed it to be, would be closer to just under 23 1/2".  This is because the two rivet rows, being 23" inches apart, would normally have an edge distance for the fasteners (fore and aft rows) from hole center to the edge of the skin of 2 1/2 to 3 rivet diameters: 3/32nds rivets x 2.5D x 2 edges = min. edge distance of 15/32nds / or round up to a half inch if you prefer - call it a patch length of 23 1/2".

If the assumptions are correct, the line up of the tear and "ghost" vertical stiffener with Station 307 is problematic.  307 minus 295 1/8 = 11 7/8 but the distance on the artifact from the edge that presumably failed against an underlying structure at 295 1/8 is 13 inches from the line of the "ghost" vertical and tear - an inch and an eighth too much to line up with Station 307.  Maybe the tear and "ghost" stiffener are not associated with Station 307, or maybe our assumptions are off - but it certainly doesn't disqualify the artifact as the patch.

I'm not sure what that vertical mark is from but it does not appear to relate to the STA 307 structure, given how the artifact would have to be laid on to work at all.  It has always been odd to me that if of the Electra that it was never riveted.  I think it has to be thrown out somehow as irrelevant to fitting the Electra.  It is interesting, but more as some enigmatic fact of something we've yet to understand, if we ever do.  In of itself it is not disqualifying, nor is it qualifying at all in my view.

I have a far deeper concern with the overall dimensions as I've found them on the Wichita photo by the scaling applied there and regret that I did not look more closely at the time:

- The photo tape appears reliable as it also accurately reflects the 1 inch spacing that we know of on the artifact in various places.

- The tape applied directly to the Electra skin above the artifact clearly validates the measurements I've given here from skin aft edge near STA 293 5/8 to STA 307 rivet line to STA 320 rivet line (visual actuals - not presuming to use station assumptions) - count the 'ticks'.  The tape is a little fuzzy there, but the 320 line may be a smidge over 12.5" from the 307, so add 1/4" perhaps.

- If the patch picked up the same forward row as the coaming, and picked up STA 320 rivet line, the distance is only 23" (or 23 1/4" with a nod to the fuzzy tape around 320).

If this is the case - and I invite you and others to inspect this work, of course - then it may be more problematic to 2-2-V-1 that we're not seeing a few surviving rivet holes remaining from those rows somewhere near one extreme end or the other of the artifact. 

I am concerned that this may be a disqualifier.

I still have doubts about the patch having picked up STA 320, but we may never know and I now don't think it matters, given what I have been able to share here.  But perhaps we'll learn more.
- Jeff Neville

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Ric Gillespie

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Re: 2-2-V-1 - patch?
« Reply #1082 on: December 21, 2014, 09:24:15 AM »

There are an awful lot of issues concerning the dimensions of the Miami patch and whether or not 2-2-V-1 can fit within those dimensions.

I disagree.

  The 2-2-V-1 thread has already gone 73 pages.  I think that it will take quite a few more pages to resolve the fitment issue.

I think the fitment issue is already resolved for you.

 
I would respectfully suggest that you start a new thread, something along the lines of “Miami Patch Dimensions” and transfer our last few exchanges to that thread.

I respectfully decline. 

Did you make the same minor error when making your calculations that suggested you had a half an inch to spare?

No.
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Ric Gillespie

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Re: 2-2-V-1 - patch?
« Reply #1083 on: December 21, 2014, 10:15:35 AM »

I invite you and others to inspect this work, of course - then it may be more problematic to 2-2-V-1 that we're not seeing a few surviving rivet holes remaining from those rows somewhere near one extreme end or the other of the artifact. 

I am concerned that this may be a disqualifier.

I understand the case you're making but it's based on a number of assumptions that may not be correct. We know the dimensions of the artifact because we have the physical object.  We can measure it's dimensions with some precision. We don't really know the dimensions of the patch because all we have to go on are fuzzy photos, so the dimensions of the patch become a matter of assumption and interpretation.

Our identification of the artifact as the patch with a high degree of certainty is based upon the preponderance of evidence - the laundry list of factors that argue in favor of it being the patch. One of those dozens of factors is what Diego likes to call "fitment." We have an artifact that even our most fervent critics admit is extremely close to fitting within the dimensions of the patch.  Arguing over tolerances of less than an inch when the available imagery doesn't support that kind of precision is pointless.

When I was at MIT I discussed the investigative process with Prof. Eagar at some length.  He has been an expert witness in literally hundreds of court cases involving aircraft accidents.  One of his most memorable observations was (I'm paraphrasing because I don't remember his exact words), "In these cases it's fairly standard find something that doesn't seem to fit the rest of the evidence, at least at first. The important thing is to look at the entire body of evidence, including the context."

If someone is intent upon disqualifying the artifact I would suggest that they find and test an alternative hypothesis for what aircraft this piece of metal came from and how it ended up where we found it.

 
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JNev

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Re: 2-2-V-1 - patch?
« Reply #1084 on: December 21, 2014, 10:51:04 AM »

I'm not intent on 'disqualifying' the artifact.  I am intent on clarifying what is before our eyes by TIGHAR's own helpful lens -

The Wichita photos with your tapes on them are not assumptions -

- The tapes you and Glickman applied clearly shows the artifact length you are talking about (24 7/16")

- The tapes you and Glickman applied to the fuselage clearly shows the length from the skin edge near 293 5/8 to the rivet line at 320 to be 24 1/2"

- The 'assumption' of the forward rivet line in the coaming, and therefore the patch as has been 'assumed', is 1 1/2" - which you, I and others have derived for good reason - and until we know of the patch having differed from the coaming we have no good reason to deviate

- The observable distance, in the Wichita photo - by your own measuring tape thereon, from the 320 rivet line to that point where the offset rivet line (forward coaming / patch) would be (1 1/2" aft of skin edge) is 23"

These, save the one assumption as to where the patch's forward rivet line truly was - if it differed from the coaming for some reason, are not 'assumptions'; they are observable in your own photos and measurable by the device you and Glickman applied in Wichita.

- The import of these things - which you understand as you've said, and I appreciate - is "if 2-2-V-1 is a remnant of the patch, and the distance between those vertical rivet lines (fore and aft) was only 23", why are there not some surviving rivet holes near the extreme ends (one or other or both) of 2-2-V-1?"

Make of it what you choose.  I am a big fan of the idea of 2-2-V-1 being 'the patch'; I've written on it and conjectured favorably to brainstorm a fit that might help prove it to be, in fact.  I'm a believer in the application of deliberate science, too.  Science cannot take shade behind 'preponderance', and now, the math and lens of our own hands in Wichita, unfortunately, trumps all the preponderance for me.  So I believe it is an observable error to ascribe my concerns to 'intent to disqualify' or to 'assumptions'.

Of course I'm content to leave the balance of the preponderance to you and others - that is all one can do here.  But if the scientific process is to be respected, I also highly suggest a review of those photos before chalking this off to some 'intent to disqualify' or 'assumptions'.

Respectfully -
- Jeff Neville

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Alfred Cramer

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Re: 2-2-V-1 - patch?
« Reply #1085 on: December 21, 2014, 11:17:27 AM »

Arguing over tolerances of less than an inch when the available imagery doesn't support that kind of precision is pointless.

Ric,
I just want to say that when the Wichita research bulletin was released, I was very excited by the yellow tape, and right away I tried to make sketches of the patch and its apparent fit to the aircraft using the measurements.  (I was grateful for the higher-res image you posted at Greg Daspit's request later on!)  Not surprisingly, it was too difficult a task for me. Clearly it's a difficult task in general.

I'm not skeptical, and in fact I tend to think that skepticism is not appropriate until one has understood a claim quite deeply. Rather, my hope was to confirm and understand more about the nature of the fit that you observed by direct physical comparison.  In other words, since obviously I wasn't there to witness the "physical comparison" between 2-2-v-1 and the aircraft, I was hoping to use the numbers supplied by the yellow tape to reproduce what you have called "direct physical comparison" on paper. (Also, having a record of detailed measurements would save the trouble of hunting down that Electra again if new information were to come forward.)

Because, as you note, tolerances are an issue, any summary or diagram of measurements ought to come with appropriate error bars.  Science usually works that way.

My sense is that others contributing to this thread, yourself included, have thought of all this, and that some are wondering whether part of Jeff Glickman's reports will detail the measurements or whether someone else ought to try to take it on.  In any case, I appreciate Jeff Neville's efforts to ascertain whether the yellow tape was in precisely the right place on the Wichita Electra and I see it as a productive line of inquiry--provided it includes error bars! 

LTM,
Alfred Cramer
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Hal Beck

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Re: 2-2-V-1 - patch?
« Reply #1086 on: December 21, 2014, 12:17:48 PM »

Ric,

A question that I've wondered about but haven't seen asked: We can see rivet lines on the fuselage around the patch but not on it.  I'm guessing this is something that you may have discussed with Jeff Glickman--did he have an explanation?

-Hal

« Last Edit: December 21, 2014, 12:19:23 PM by Hal Beck »
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John Hart

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Re: 2-2-V-1 - patch?
« Reply #1087 on: December 21, 2014, 12:50:58 PM »

I have no expertise to give to this discussion but as an interested observer thought of something you may wish to consider.  I don't know how hard it would be to accomplish from mechanical standpoint, being a lowly pilot, but it has been on my mind for some time.  Your analysis may have already considered and rejected this notion. If so, sorry for the spam.

I look at the closeup picture of the window before it was removed and wonder about the ~2 inch piece of skin between the aft end of skin at station 293 5/8 and the window combing.  If the window attachment were used for the patch and it was laid over this small segment of skin there would be this clear 1.5-2 inch separation between the line of skin at 293 5/8 and the front of the patch.  That is not clearly evident in the post patch pictures.  It also would have resulted in a potential for airflow to separate the forward edge of the patch as it overlays this small section of skin.  This would not be a concern for a window combing but a patch would concern me from an aerodynamic standpoint.  One rivet pops and you have airflow under the patch.  I would think it would be preferable to remove that small segment of skin (would require a piece of skin to be removed or overlaid on the upper part of the patch), drill out the rivets on station 293 5/8, slide the forward edge of the patch under the skin at 293 5/8 and re-rivet on sat 293 5/8.  That would provide a smooth edge for your hinging action to separate against.  It also would explain your patch length without existing rivet holes on the fore edge.  I think it would also help you align the flat sheet of aluminum to the curvature of the fuselage during installation.

Again, no fabrication expertise to determine if this is feasible or if your examination has already eliminated this possibility, just a thought.  More power to you.
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Brad Beeching

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Re: 2-2-V-1 - patch?
« Reply #1088 on: December 21, 2014, 03:44:24 PM »

Is it possible that when the patch was installed, a "Backing Strip" was rivited along the seams to stiffen the joint? If I've followed all this correctly, there is a matter of a few inches shy of reaching a stiffener or stringer. Could the installer have rivited a strip of .032" material to make up the distance or stiffen the seam?
Brad

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Ric Gillespie

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Re: 2-2-V-1 - patch?
« Reply #1089 on: December 21, 2014, 04:10:28 PM »

A question that I've wondered about but haven't seen asked: We can see rivet lines on the fuselage around the patch but not on it.  I'm guessing this is something that you may have discussed with Jeff Glickman--did he have an explanation?


We can see some of the rivet lines on the patch in the Miami Herald taxiing-out photo.  Jeff Glickman has found evidence of the other rivet lines that correspond to the artifact by means of a proprietary analytical process that I'm not competent to explain but I've seen the result.  We hoped to get a more direct look at the rivet lines on the patch via the Albasi photo but the resolution is not as good as the Miami Herald photo.  To answer your question, I haven't discussed it with Jeff but it's my impression that we can't see rivet lines on the patch in the Albasi photo because the patch is so shiny and reflective.
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Ric Gillespie

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Re: 2-2-V-1 - patch?
« Reply #1090 on: December 21, 2014, 04:36:42 PM »

If the window attachment were used for the patch and it was laid over this small segment of skin there would be this clear 1.5-2 inch separation between the line of skin at 293 5/8 and the front of the patch.  That is not clearly evident in the post patch pictures.

I think there are some legitimate questions about what the front edge of the patch looked like.  For example, in the Miami Herald takeoff photo we see a hard line along the bottom edge of the patch but on the front edge.  Is it just the lighting or is something else going on?
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Hal Beck

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Re: 2-2-V-1 - patch?
« Reply #1091 on: December 21, 2014, 05:40:41 PM »

Thank you for the reply, Ric,

I misstated my question somewhat due to some last-minute editing.  In the case of all the photos besides one, the resolution is poor, so it is no surprise that no rivet lines are seen.  But the photo taken outside the hangar at Darwin (http://earchives.lib.purdue.edu/cdm/singleitem/collection/earhart/id/284/rec/14) strikes me as being well-resolved enough to see rivet lines on the patch.  As I said in my last post, we can see vertical and horizontal rivet lines ending at the patch, but none are apparent on the patch.  I think it is definitely worth making the trip to Purdue you mentioned a few days ago to get the best copy of this picture available.
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John Hart

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Re: 2-2-V-1 - patch?
« Reply #1092 on: December 21, 2014, 08:03:38 PM »

My thinking was they would have kept with the standard overlap top to bottom and fore to aft.  This makes sense to shed rain from above and provide a smooth path for airflow from forward.  To install the patch, remove the small segment of skin aft of 293 5/8 and cut out the small piece on the upper corner of the window opening above it.  Put the top of the patch under the skin above and the front of the patch under the skin at 293 5/8.  Use the holes as guide to drill and re-rivet.  Overlay the patch over the lower and aft skin riveting to the existing window attachments.  Underlap top and front, overlap aft and bottom.  This would explain the smooth edge on the top and front of the patch and rough edges bottom and rear as the top/front would tear from under the overlapping skin instead of rivet heads. 
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Ric Gillespie

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Re: 2-2-V-1 - patch?
« Reply #1093 on: December 21, 2014, 08:27:50 PM »

As I said in my last post, we can see vertical and horizontal rivet lines ending at the patch, but none are apparent on the patch.  I think it is definitely worth making the trip to Purdue you mentioned a few days ago to get the best copy of this picture available.

I agree that we need to take a close look at the Purdue print of the Darwin Fueling photo, but don't confuse skin edges with rivet lines.  I can see skin edges in the photo but I can't see rivet lines except for some possible vertical lines. 
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Bill Lucas

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Re: 2-2-V-1 - patch?
« Reply #1094 on: December 22, 2014, 08:58:32 AM »

That thin metal (.032) laying on the surface of the outside skins is gonna play havoc with trying to figure
out the forward and rear edges due to lighting in those photos. The Miami photos are probably
influenced by the lighting as far as forward and rear edges go.

Bill
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