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[JNev]

Could it be possible that the stiffeners were added after the Darwin picture was taken?

I doubt that.

Of course I also am of the opinion that this picture does not exclude the likelihood of light stiffeners being present, as I've said.

That said I respect the alternate view - but would note that the photo deserves serious study before it can be said that it proves 'no stiffeners are present'.  No doubt our critics will disagree with me - that's OK.  But I don't know what all is being reflected in that shot, and whether we're seeing a true distortion in the light on the surface of the metal, or whether light is being reflected oddly there for another reason.  Recall that there was lots of discussion about what we saw in the Miami photo reflection as well - some said 'clouds', others (like me) believe we're seeing rivets, among other things - including the crowd, etc.

[JNev]

I'm going to go ahead and go wayyyy into speculation; completely unscientific here, guys.

look at the picture of the plane in the hanger.  The patch appears to have a crease, that starts on the right side of the patch and travels to the left, about halfway down.  It travels at about a 20 degree slant from about 60% up the patch on the right edge, to about 40% up the patch, near the center... kind of fading out at about the center of the patch.  See it?  It appears to be the bottom of the oil-canned 'dent'.

Now look at the patch.  The same crease appears to be on it.  On the right you can see it starting at about the second row of rivets, and it travels down to the left near the center vertical piece of tape, disappearing near the center.  What remains of the oil canned dent is to the left of Ric's right hand.

Again, completely unscientific.  Could have happened at any time.  Could be a trick of light... but damn if it doesn't look the same to me...

Good catch, I see what you mean.  That could be an exciting match -

Or a coincidence.  I remain skeptical of the import of this 'oil canning' - both as to how prominent it may really be, whether it 'could not exist' with bracing present (I believe it could) - or whether this is some effect of the light.

The main corroboration I see that this is true metal distortion is in the tell-tale evidence present in the Darwin ramp photo.  I've attached that here.

[JNev]

Here are two more pictures.  I've been unable to load what David Billings gave me, but he sent these as well.

Bottom line, I am not a photogrammetry expert by any means.  I think the light / sources of light, etc. would have to be carefully analyzed here to be able to ever say "there are no stiffeners", but again, respect why some believe that is true.  Enjoy.

[Bill Mangus]

Once it's pointed-out, it's pretty easy to see.  I make it out to be a fairly shallow dish-shaped depression in nearly the entire top half of the patch.  It's a little harder to see in the ramp picture, but it appears to be there.

Given the depression is in an inward direction, I'm wondering if that "pressure" caused the impression of a vertical stiffener found on 2-2-V-1 this past August?  There don't seem to be any similar impressions of the horizontal stiffeners, so I'm also thinking the 'oil-canning' might have caused the vertical stiffener attachment point at the top of the patch to 'pop' at some point in the journey. 

An alternative is that visible depression may have been the reason the vertical stiffener was added, either there in Darwin or some where earlier in the trip.

Nice picture, good contrast and reasonable resolution.  I wonder if a first generation print or even the negative may still exist somewhere.

[Jerry Germann]

Here are two more pictures.  I've been unable to load what David Billings gave me, but he sent these as well.

Bottom line, I am not a photogrammetry expert by any means.  I think the light / sources of light, etc. would have to be carefully analyzed here to be able to ever say "there are no stiffeners", but again, respect why some believe that is true.  Enjoy.

Seems to be a lot of distortion for whatever reason in the photos ,.....note how the top and sides of the regular window take on an irregular shape.

[James Champion]

One thing for sure - this patch was not a perfect fit. Some of the rivets on the stiffeners would have had more stress than others. On the reef, stress corrosion would have weakened the heads of the most stressed rivets first. The heads would have detached transferring the stress to adjoining rivets which would then fail in time. This is unlike normal aircraft structure where the parts fit properly and the stresses are distributed evenly.

[Monty Fowler]

One thing for sure - this patch was not a perfect fit. Some of the rivets on the stiffeners would have had more stress than others. On the reef, stress corrosion would have weakened the heads of the most stressed rivets first. The heads would have detached transferring the stress to adjoining rivets which would then fail in time. This is unlike normal aircraft structure where the parts fit properly and the stresses are distributed evenly.

That's a good point, James, and coupled with the newly-speculated reason that the rivets simply dissolved over time due to a corrosive reaction with the ALCLAD and salt water, makes a lot of sense.

LTM,
Monty Fowler, TIGHAR No. 2189 ECSP

[JNev]

I can 'get it' a bit better about what the critics seem to think if I remember the Sta 307 vertical member, I think.  That, more than the longitudenal stiffeners that many of us believe were there, might resist the degree of oil canning suggested by this photo.  Not a bad point.

That said, I still wonder if the light is being 'true' to metal deformation, or if there are other reasons we're seeing what seems like a 'dish' in the metal from about mid-waterline up.  I've highlighted a few notions in the attached, having to do with -

1) A comparison to two other visible areas that also display similar light-line disruptions; one of those (the forward example) appears to have more distortion to me, and is on a known 'OK' section of fuselage above the cabin tanks (Lockheed-installed cabin window covering) - which has me continuing to wonder about 'tricks of the light' somehow - and

2) Reflections?  Are we seeing some faint outlines of wing / nacelle or something similar in the hangar area around the Electra?  Look at what appears to be the wing trailing edge reflected along the upper tip of the RH tail fin.

3) A completely different area - a shiny skinned door on the Electra; how much 'distortion' is really present, and how much is perhaps over-stated by the lighting?

4) The ubiquitous Vega from overhead - with ply skins showing lots of 'puckers'; these are mild deformations, but the more odd the light angle (oblique, here) the more pronounced - until they look drastic.  In fact, these are quite normal to the structure.  Stressed wood skins behave in a similar way to stressed metal skins.  I think the point of our critics might be that stiffening members do tend to contain skin irregularities - fair enough in my view; that said, stiffeners also can deform gently with the skin - especially where a large area, blunt depression might occur; with wood, it would either break, or tend to return to shape - but metal can well be set to the new shape.

Obviously, I personally believe there may well be a number of explanations for this interesting feature other than 'oil canning because no stiffeners are present'. 

I continue to hold that the newest Miami pictures may be the best set of clues yet - anxious to see them studied: one great picture could spare us all these many words...

[Greg Daspit]

One of the theories about the window being installed is that it was for the navigator and needed to be optically correct. This may mean it had to have flat glazing. If this was the case the top edge of the window frame may be straight.  Because the rest of the fuselage is slightly curved, then when they installed the patch it may look flat or deformed at the top compared to the rest of the fuselage.

[JNev]

Hadn't thought of that, Greg, and I don't know if the window had to be optically correct or not.  Good point though - an example of the oddities that the patch installer may have had to contend with.

I was fascinated by the clear 'bend' near the upper edge of the window covering in this shot made in Miami - it suggests some slight adjustment in contour along a waterline to deal with some fitment issue or other -
 

[Ron Lyons]

I think one thing we need to keep in mind is that the light exaggerates any deformities that are there.  If you've ever done body work on a car, or had one with a tiny dent in it, you can see this.  Just the slightest variance from straight, especially on a glossy sheen really refracts the reflection. 

I have no problem with there being an 'oil canned' skin, AND stiffeners present.  The vertical one, if there, wasn't riveted and stretching or bending or shrinking the skin would make that metal not lay flat against that stiffener.  1/2" of play would cause a visible 'dent'.

The picture of the plane door is the proof of that.  Which is it?  Amelia was flying around with a door bent up like an accordion, or was the light just making it look worse?  Hard to fathom she'd fly something with the door that bent up, there's no way it was truly "that bad" or it would have been repaired.

[JNev]

Good points, Ron.  I still tend to think that fitting this cover might have been a bit of a bitch, given the size of the area to cover and contours - and likely Earhart's desire that it be as unnoticeable as possible.  No matter how it was braced, I suspect there was some deformity in it that fly-specking would turn up.  I also still suspect it was 'lightly braced', mainly because I suspect stiffeners may have had to be formed by simple bending of available sheet, and that some degree of contour conformity was worked-in as the skin went on.

[Ron Lyons]

I'm sort of a backyard mechanic... so I know how I would have made the patch, but I would imagine the people that made THIS repair were much more talented than me. 

Here's how I see what happened.

1. they take the coaming off by drilling out the rivets.  They throw it in the trash, or maybe use it to cut a piece the same size to make the patch.
2. They decide it's pretty big and it's going to bend, so they rivet 5 thin pieces of stiffeners to it, sort of evenly spaced but not really taking into consideration where those 5 stiffeners will line up on the plane.
3. They test fit it on the plane and figure out what they need to do to get it to wrap a little bit around the curvature of the plane.  Up at the top they likely beat a curve into it so it would lay flat onto the surface of the plane and not leak water.  In doing all this they bend and dent the piece of metal a little bit, leaving it how we see it in the pictures on the plane (a dent in the top right quadrant, a bit of a bowled, sagged effect near about the 4th row of rivets... nothing perfectly flat, kind of warped)
4. After riveting it on the plane, they notice that it's still 'oil canning' because if you press in on the center of it it bends in an inch or so... so they decide to put a stiffener inside where the original vertical piece was.  They go inside the plane and cut some sort of angle iron or whatever and somehow attach it to the top where the original vertical stiffener was and then at the bottom... they may have attempted to curve or cut a relief in this piece to make it match the gentle curve of the plane.  It likely touched the skin or was close to it, but that would change if the plane went airborne as the pressure and wind moved the panel in and out as the air moved over it.
5. Thinking that it was well enough for their patch job, they rolled the plane out and these pictures were taken, dent already there, bracing already there, patch already installed, etc.

I think it had a minor dent in the upper right quadrant that was there from when it was installed and beat/bent/warped into place, and there also may have been a stiffener vertically in the center of the window (where the original one was on the skin of the plane above it) kind of haphazardly almost wedged into the window frame opening or whatever remained of it on the inside of the plane. 

That's how I personally would do it.  If the argument is I'm not a plane mechanic and they would have done a hell of a lot better job, that's an argument I think is feasible

[Ron Lyons]

BTW: More speculation

The horizontal stiffeners were riveted on.  We know this because of the rivet holes.. there are no 'markings' where that left an imprint on the piece because in theory they were held tight against it.

The vertical one wasn't riveted (if it existed).  We have an imprint in the skin because that stiffener wasn't held flush with the skin; as the wind beat it around a little bit (oil canning) it repeatedly forged an indentation from the slapping action of the skin against the stiffener.  If they would have riveted it we likely wouldn't be able to tell (other than the holes) like on the horizontal ones.

[Jeff Palshook]

I gave Elgen that template in 1992. If he has exactly matched it to a PBY he has never told me.  If he has a detailed report that supports his claim he needs to produce it before he makes the assertion.  That’s the standard we follow.  To be credible, that’s the standard he must follow. 

The attached photo was posted to a blog by his grandson.  It supposedly shows the template and the ‘exact fit” of the template to the upper wing surface of a PBY. As poor as the photo is, I can see a big problem.   The artifact has four parallel rows of 3/32nd inch rivets. One edge of the artifact (the edge with the “tab” sticking out) tore along a double staggered row of 5/32nd inch rivets. I see no double row of larger rivets on the PBY.  The parallel lines of rivets are clearly all the same size.
To match the artifact to a PBY (or any airplane) takes more than finding five parallel rows of rivets roughly for inches apart.  We found places like that on several different types.  To have a match to the artifact requires:
•  Four rows of 3/32nd inch rivets with a pitch (distance between rivets) of 1 inch.
•  The distance between parallel rows must be nominally, but not consistently, 4 5/8ths inches.    
•  A double staggered row of 5/32 inch rivets with a pitch of 1.5 inches, except for one anomalous spot where there is a 1 5/8ths inch gap.
•  The rivets must be AN 455 brazier heads
•  The skin to which they are attached must be .032 24St Alcad

If Bill Mangus is correct that the skin thickness in that area was .045 that puts another nail in the coffin.

Ric,

Could you clarify the 4-5/8 in. nominal spacing between rivet rows in 2-2-V-1, as you stated it in the above quote?  Your 1992 "TIGHAR Tracks" article "Through the Flak" http://tighar.org/Publications/TTracks/1992Vol_8/Flak.pdf
has a rather detailed drawing of the rivet pattern in 2-2-V-1.  The largest spacing between rivet lines shown on that drawing is 4-1/2 in.  Also, measuring as best I could from the photos you posted several months ago of the temporarily flattened 2-2-V-1, with measuring tape laid across 2-2-V-1 in the photos, I got rivet spacing between rivet lines of about 4-1/16 in. to 4-1/4 in.  I don't see where a measurement as large as 4-5/8 in. (4.625 in.) would have come from.  Perhaps 4-5/8 in. in your post quoted above was a typo?

Jeff P.