TIGHAR
Amelia Earhart Search Forum => General discussion => Topic started by: Kevin Weeks on June 25, 2019, 02:46:12 PM
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I had a question regarding wing panel comparisons of nearby wrecks and the artifact. I did some searching of wrecks from Canton Island some time ago and the artifact. I came up with an article about B-24 wing panels that showed a claim that the artifact came from a section of that wing. it was debunked due to thickness and rivet sizing being too large. I was wondering if it was possible that this piece may have come from the wing of a C-47 that crashed on sydney island?? especially since that wing was torn off before the plane struck the ground and burned, never to be recovered.
https://tighar.org/Projects/Earhart/Archives/Research/Bulletins/07_Sydneycrash/07_Sydneycrash.html
this came to me on friday as I walked under the freshly stripped and polished wing of a DC-3 at the new england air museum with my son not 10 feet away from the Lockheed Electra they have.
I have tried searching for a C-47 wing repair manual such as was used to debunk the B-24 claim. it makes sense to me that the C-47 skin would be thinner and use smaller rivets that would closer match the construction of the wing panels in these planes. looking over at the construction of the Electra shows completely different construction/rivet patterns across the entire plane. I had trouble looking at it and seeing how they would deviate from their standard rivet patterns even for a small patch especially being able to compare the two so closely.
has this been investigated?? i would be surprised if it had not.
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of course after posting this I did find a very hard to read structural repair manual for a dc-3/c-47.... it's looking like the wing panels are possible too thin in most areas, so we are going from one extreme to the other?? the inner front edge of the wing appears to be the only skin that is .045 thick...
http://www.avialogs.com/index.php/en/aircraft/usa/douglas/dc3c-47/structural-repair-manual-for-the-model-dc-3.html#download
it calls out ad6 rivets which are 3/16 brazier head. great read in general for skin repair and rivet patterns.
just looked at the 2-2-v-1 article again to refresh my memory... seems I was mistaken on the thickness. thickness is .032 and the rivets were 3/32 and 5/32... hmmmm
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On July 16, 2017 I inspected the portion the DC-3/C-47 wing section at the New England Air Museum alleged to resemble Artifact 2-2-V-1. At that time the wing section was out behind the museum, stored outdoors with various other bits and pieces of aircraft. There was no way to check the thickness of the skin but, although there were some general similarities in rivet pattern, the rivet type, rivet size, rivet pitch, and spacing between rivet lines did not match the artifact. Not even close. TIGHAR videographer Mark Smith recorded the investigation.
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As I said I would be surprised if you hadnt checked this! I remember you making this trip as I had planned to attend but I had other commitments unfortunately.
The link I attached earlier does show some good information on rivet sizing and repairs for different t skin thickness. I wonder if the specific section could have been the repair from the clipped guy wire that required the plane to be repaired for so long. That would be the only reason for the irregular river placement on a aircraft skin.
Thoughts... not worth much without that velum print to slide over every aircraft that went through canton!
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On July 16, 2017 I inspected the portion the DC-3/C-47 wing section at the New England Air Museum alleged to resemble Artifact 2-2-V-1. At that time the wing section was out behind the museum, stored outdoors with various other bits and pieces of aircraft. There was no way to check the thickness of the skin but, although there were some general similarities in rivet pattern, the rivet type, rivet size, rivet pitch, and spacing between rivet lines did not match the artifact. Not even close. TIGHAR videographer Mark Smith recorded the investigation.
Regarding the Youtube video recently posted “C-47 wing inspection” In the video the rivet size was thought to be too large and disqualify a DC3/C-47 wing, per the sample examined, as a possible candidate for 2-2-V-1.
https://www.youtube.com/watch?v=GlVLyOfsZ3c
However, a link in the comment section has an Analysis Tom Palshaw’s did as a follow up after the video. In that analysis he states the rivets are the same as found on 2-2-V-1. He also states the larger rivet pitch was found to vary making it a question to examine for a possible fit.
https://istigharartifact2-2-v-1apieceofac-47wing.yolasite.com/
Could discoloration around the rivets or some other factor cause them to appear bigger than they are based on side by side visual comparison? Was a measuring instrument used to verify the rivet size on the wing examined? Did Mr. Palshaw do this when he removed a rivet? What is the reason for the conflicting sizes claimed for the rivets?
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Could discoloration around the rivets or some other factor cause them to appear bigger than they are based on side by side visual comparison?
There was no discoloration. Both the wing and the artifact are the dull gray of oxidized aluminum sheet.
Was a measuring instrument used to verify the rivet size on the wing examined?
No. The size difference was immediately apparent and obvious.
Did Mr. Palshaw do this when he removed a rivet?
I have no idea. He doesn't say.
What is the reason for the conflicting sizes claimed for the rivets?
Somebody is wrong.
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Could discoloration around the rivets or some other factor cause them to appear bigger than they are based on side by side visual comparison?
There was no discoloration. Both the wing and the artifact are the dull gray of oxidized aluminum sheet.
Was a measuring instrument used to verify the rivet size on the wing examined?
No. The size difference was immediately apparent and obvious.
Did Mr. Palshaw do this when he removed a rivet?
I have no idea. He doesn't say.
What is the reason for the conflicting sizes claimed for the rivets?
Somebody is wrong.
It’s hard to tell the size of the rivets by looking at the video. The wing being flat and outside may allow residue from pollution or dust in rain (discoloration) to collect around its rivets.
There may be an optical illusion issue with comparing a circle in a field of smaller holes to a circle surrounded by same size circles. There are optical illusions that can fool you. I’m not saying this is one but it would be nice to actually measure the rivets instead of visual comparison. Some examples of known illusions.
https://en.wikipedia.org/wiki/Ebbinghaus_illusion
https://en.wikipedia.org/wiki/Delboeuf_illusion
It would be helpful if he could send us a picture of the rivets with a digital caliper to prove his claim for the size.
Some concerns with his analysis:
1. The wing from the Sydney crash was painted green. Not sure if testing was conclusive that 2-2-V-1 never was painted or just no paint was found?
2. The claim the aluminum was a “Match” to WWII aluminum. A graphic he used is one I did and posted on this Forum. I did that graphic to show the 3 elements in question might fit between the two time periods. Not a “match” one way or the other IMO. Inconclusive.
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A few years ago hyperspectral imaging was done on this object
https://tighar.org/smf/index.php/topic,1456.15.html
That may show any residual paints
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It’s hard to tell the size of the rivets by looking at the video.
It wasn't hard in person. That's why we didn't do any measuring.
Some concerns with his analysis:
1. The wing from the Sydney crash was painted green. Not sure if testing was conclusive that 2-2-V-1 never was painted or just no paint was found?
We asked that question early on. A lab found no trace of paint on the artifact. Impossible to know if it was never painted. One thing we know for sure; 2-2-V-1 was scrubbed around in an abrasive environment long enough wear all of the edges smooth. It's not surprising that any trace of paint is gone.
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If in a follow-up inspection it was found that the rivets are -3, I think it would be helpful if Tom Palshaw could provide documentation showing how he measured them. I think he has a good case here if he can confirm or document better that the rivet sizes match.
Based on what I could see in the video, the rivet row spacing and pitch appeared to be close to a match. It would be helpful if they were both measured and documented by photograph so we can verify.
I agree with the reasoning that a structural member on the aircraft next to the edge that failed by folding is not needed. Someone could have placed their own edge to help fold it straight.
The picture he posted on his web site clearly shows that the larger rivet row has a pitch that varies. I question how one could claim to match or disqualify something spaced like that without a lot more samples that all showed the same spacing irregularities. It is interesting that both the wing and artifact have an irregular pitch or anomalies though. For now I don't think that row not being exactly the same is a disqualifier.
Here is what I would like to see tested and documented somehow for further review: (Others may have better ideas)
1. Confirm the rivet hole sizes. The physical test of fitting a -3 into the holes and then failing to fit a -4 in the holes seems conclusive that the holes are for -3. But this physical test was not done on the wing. A rivet was removed at a later date so if that test could still be done it would be a good to document it. Photos of a rivet gauge used in the process may help the viewer.
2. Confirm the size of all rivet heads by measurement. Document by photograph of digital caliper or head rivet gauge. A sample of a few rivet heads should be examined. Do same for new rivets out of the box.
3. Confirm both the spacing and pitch of rivets. I think adhesive measuring tape works better for the viewer of photos. It stays flush so is not distorted by being off the surface when photographed at an angle. Place tape next to each row to determine pitch and one or two strips perpendicular to the rows to get their spacing. This includes measuring both the larger rivet rows. Even if the pitch varies the distance between rows can be verified.
4. Measure the thickness of the metal. I don’t know what the best tool for this would be with the metal in place? Whatever tool is used, photograph it being used.
5. Check for labels that still may be viewable on the aluminum. Based on the new font/ label designation information, it may help to know where it was manufactured
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Based on what I could see in the video, the rivet row spacing and pitch appeared to be close to a match.
But there is more to it than just row spacing and pitch. If 2-2-V-1 is from the wing of a C-47, all aspects of the artifact must match. Beyond row spacing and pitch, the following must also match:
• rivet size (shaft diameter)
The rivet on 2-2-V-1 has a shaft diameter of 3/32 inch - source NTSB Laboratory.
• rivet length (shaft length)
The rivet on 2-2-V-1 has a shaft length of 3/16 inch - source NTSB Laboratory.
• rivet material
The rivet on 2-2-V-1 has a dimple in the center of the head, signifying it is made of A17ST alloy - source "Aircraft Maintenance and Repair" Northrop Aeronautical Institute, 1955. See attached PDF of rivet coding.
• rivet head type
The rivet on 2-2-V-1 is a "brazier" head. A brazier head rivet has a low profile, minimizing drag. There are two kinds of brazier head rivets, the "full brazier head" and the "modified brazier head". As early as 1930 and as late as 1941and possibly later, the "modified brazier head" was known as the "mushroom head." The rivet on 2-2-V-1 is what is now known as a "full brazier head" rivet. See attached illustration.
Lockheed Electras had dimpled "full brazier head rivets" identical to the rivet on 2-2-V-1. See photo below.
The photo of the rivets on the C-47 wing at NEAM is included below for comparison.
• sheet thickness
The 2-2-V-1 sheet has a thickness of 0.032" - Source NTSB Laboratory
• sheet alloy
The 2-2-V-1 sheet alloy is aluminum plus 4.49% copper, 0.62% manganese, and 1.48% magnesium, plus traces of eighteen other elements. So far, the earliest available ALCOA specifications for 24S sheet (1941) are 4.5% copper, 0.6% manganese, and 1.5% magnesium. No other elements are mentioned.
Aluminum samples from known Electras:
1935 - 4.29% copper, 0.43% manganese, 1.49% magnesium
1935 (same airplane) - 4.06% copper, 0.48% manganese, 1.46% magnesium
1935 (different airplane) - 3.55% copper, 0.45% manganese, 1.46 magnesium
The one WWII sample for which we have a good date of manufacture - B-17 Shoo, Shoo Baby:
1943 - 4.30% copper, .45% manganese, 1.31% magnesium
The alloy percentages in the 1943 B-17 for the elements specified by ALCOA are most similar to one of the samples from a 1935 Electra.
Clearly, no conclusion about the age of 2-2-V-1 can be drawn from the available data.
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Hey Ric...Happy Birthday!!! Hey I was on youtube tonight and was watching this one video. At first I thought I had seen it before, that is until they started talking about the wing strength. In the video they talk about the wing is able to stand up to 80,000 pounds, and whats also neat is the placement of rivets and how they go about doing it! Anyway, thought this video may be very helpful and resourceful. But, in actuality, if the wing is able to stand up to 80,000 pounds...then what kind of tramatic incident would do creat excessive damage?
https://youtu.be/MM_sVVqrrA8
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Thanks Randy. That's an excellent tutorial on how Lockheed built airplanes in 1940. The segment about riveting (starting at about 22:52) is especially interesting. The techniques were probably very similar in 1936 when c/n1055 was built.
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Tom added some information on the C-47 rivets and how he measured them
https://istigharartifact2-2-v-1apieceofac-47wing.yolasite.com/
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I’ve been spending a lot time researching the possibility 2-2-V-1 is from the wing of a C-47. The rivet pattern on the wing at the New England Air Museum (NEAM) is closer to the pattern on 2-2-V-1 than we originally thought, but it’s not a perfect match. That may be because the wing at NEAM is from a C-47B 43-49197. The airplane that crashed at Sydney Island was C-47A 43-30739.
The C-47B had a two-stage supercharger for better high altitude performance on the China-Burma-India (“Hump”) route. There should have been no C-47Bs passing through Canton en route to the Southwest Pacific Theater.
Last Saturday, I spent a couple hours with C-47A 42-92841 at the the Dover AFB Air Mobility Command Museum. With the enthusiastic cooperation of museum staff, I was able to get up on the wing and inspect the area in question but the sloping, slippery surface was a challenge. I’ve attached a few photos.
• All of the rivets on the Dover C-47A are dimpled A-17ST rivets. Although they don't show up in Tom Palshaw's photos, the rivets on the NEAM are certainly also dimpled. Un-dimpled rivets are pure aluminum and far too soft for use on load-bearing structures.
• The rivets on the Dover C-47A are “full brazier head” rivets as is the surviving rivet on 2-2-V-1.
• The general pattern of small rivets on the Dover airplane appears to be the same as on the NEAM wing, but it was too dangerous to attempt detailed measurement of pitch and intervals between rows.
• The small rivets on the Dover airplane are #3s. The small rivets on the NEAM wing are probably also #3s despite our impression back in 2017.
• The double row of large rivets on the Dover airplane is different from the NEAM wing. The NEAM wing has an inner row of #5s and an outer row of #6s. On the Dover airplane, the rivets in both rows are #5s.
• Tom Palshaw says there are anomalies in the pitch of the #5 rivets on the NEAM wing (he did not provide photos). There are no apparent anomalies in the pitch of the large rivets on the Dover airplane.
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The are general similarities in the rivet patterns on 2-2-V-1 to the wing of the C-47A at Dover. If 2-2-V-1 is from a C-47, the December 17, 1943 loss of a C-47A at Sydney Island is, without doubt, the most likely suspect. Sydney (now Manra) is 195 nautical miles from Niku and was part of the Phoenix islands Settlement Scheme. Five families from the settlement on Sydney were moved to Niku in the early 1950s. Palshaw’s hypothesis is, 2-2-V-1 is a piece of the right wing of the Sydney wreck, salvaged by locals, and brought with them to Niku. There are some problems with that hypothesis.
• According to the AAF accident report, "the right wing had clipped a tree, outside of the motor, at the beach while coming in low from the water. This was verified by the natives on the island. The right wing struck a tree, breaking the tree off about thirty feet from the ground. … A portion of the right wing was found approximately 86 feet inland. The plane went up over the trees for a distance of about 150 yards and started coming down through the trees again, shearing off the trees until it came to rest approximately 376 yards from the first tree which was struck. The motors continued on after the plane came to rest, one for 46 yards and the other 63 yards from the plane. The airplane burned completely with the exception of the tail section and the left wing from the motor out, also the right wing which had been lost.”
Included in our copy of the accident report is a bad photocopy of a photo of the right wing (attached). The part of the wing where 2-2-V-1 appears to fit (between the engine nacelle and the aileron) is right where the tree sheared through the wing. The metal in that area should show impact damage similar to wreckage we retrieved from the Idaho Electra cash site. (photo attached). If 2-2-V-1 is from the Sydney wreck it is more likely from the left wing.
• There was certainly no "cold working" of the C-47 wing prior to the accident. Tom Palshaw suggests the “cold working” on lower left of 2-2-V-1 occurred after the sheet was salvaged. I’m not sure that’s possible. I’ll ask the metallurgists.
• We know 2-2-V-1 spent considerable time under water - long enough for coral growth to form - and scrubbed around on an abrasive surface (such as the reef flat) long enough to wear all of the edges smooth. Those features are hard to square with a piece of metal salvaged on land and brought to Niku by a settler from Sydney.
• There was no casual inter-island commerce. The first settlers from Sydney arrived in the early 1950s, but in 1944 and '45 American servicemen traded with locals on Nikumaroro for carved wooden boxes with small decorative metal inlays said to be from "the downed plane" which had been on Gardner when the first settlers arrived. Laboratory testing has confirmed the metal to be ALCLAD aluminum. So the settlers on Gardner apparently had access to aircraft aluminum before any settlers from Sydney arrived.
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Another thing to perhaps consider is the difference between how 2-2-V-1 looks compared to the relatively pristine pieces seen on the boxes -- no coral growth, oxidation, etc. I don't know if the colonists had tools enough to polish what aluminum they found but 2-2-V-1 would hardly be considered useful enough for decorative pieces. I don't really know, though. Would 2-2-V-1 "clean-up" nice enough to be a decoration?
(Rainy and cold here; I'd rather be thinking about a warm Pacific island :D)
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Would 2-2-V-1 "clean-up" nice enough to be a decoration?
I don't think so, but 2-2-V-1 shows no sign of having had pieces cut put of it. If the locals were using aluminum from the Electra for the inlays, the metal was coming from other salvaged bits.
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I'm confused now, ... so are we now saying that this piece likely has nothing at all to do with AEs plane, OR are you saying that they used a piece from another plane entirely to possibly cover the window of AEs plane and this might be it?
Need some clarification please.
Thanks
Jerry S
LTM
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I'm confused now, ... so are we now saying that this piece likely has nothing at all to do with AEs plane, OR are you saying that they used a piece from another plane entirely to possibly cover the window of AEs plane and this might be it?
We're not saying anything. We're doing the same thing we've been doing since we found the piece in 1991. We're trying to figure out where 2-2-V-1 came from and how it got to where we found it.
• We are comparing 2-2-V-1 to photos of the patch on AE's plane and we're finding remarkable similarities. It is virtually certain that AE's plane was once at Nikumaroro, so it's reasonably possible that part of the plane may have ended up where we found it.
• The artifact is also similar to a section on the wing of a C-47A. A C-47A is known to have crashed on another island in the Phoenix Group so it's reasonably possible that part of the plane may have been salvaged and brought to Nikumaroro.
• We're not aware of any other reasonable possible sources for the artifact.
Which explanation is most reasonable? To answer that question we're collecting more detailed data on the artifact, the patch, and the C-47A.
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You guys are confusing each other.
What Ric is trying to say is that 2-2-V-1 was not the source of the little bits of Alclad that the islanders used to inlay on the boxes and other decorative items they traded with the Coasties. We know this because 2-2-V-1 has no signs of having little pieces cut out of it, so the source for that material had to be other salvaged aluminum.
2-2-V-1, if it is the patch from AE's plane, didn't come from another aircraft, it was cut from a fresh sheet of Alclad.
I hope that helps clarify.
amck
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As late as it is early, I thought I better send this or I'll totally forget it entirely. Anyway, I was online researching the other night and from reading an old Miami Herald online back on the week that Amelia was there...it went on in the article that the old Miami airport was turned into a Naval station. With that I've been doing some searching on C-47 that Ric was mentioning, and I ran across this. Very interesting to say the least, and it might hold the answer to our elusive patch.....
Henry Guerin, who started with Douglas in the early 1920s, was now his wartime factory manager at Santa Monica. Guerin had developed a “Hydropress” process that employed male dies made of metal with a “universal” female die made of rubber. This process cut aluminum alloy sheets, and shaped them in a single operation. The Guerin Process was responsible for turning out aircraft parts at undreamed of speed. This process eventually led to closed wing compartments and leakproof integral fuel tanks, without which long range aircraft like the C‑54 would not have been possible. The Guerin hydropress machinery and methods were also later adopted by the auto industry to meet the wartime production needs.
Other parts of the airplane, fairings, access panels, cowls, and wing fillets once formed by hand, were now consigned to Guerin’s presses or stretch‑formed over dies. The objective was to develop a machine tool or technique to replace a hand tool operation. Rivet machines replaced hand riveting, and combined, the improved production techniques cut manufacturing time by 50 percent.
http://www.dc3history.org/c47dakota.html
With the information on Henry Guerin and starting with Douglas in 1920...I'm curious to know Ric if the metal used in the patch was widely used by other aircraft companies at the time Amelia's plane was built. With Guerin "Hydropress" it makes you wonder during that time frame and with war in the foreground that one type of metal was used. Granted I'm no historian on aircraft metal but it would make sense if you were going to mass produce planes at any given moment. Two things we might need to consider with more information on the patch is what kind of record keeping did George Putnam have in regards to the cost of having this done to the plane. Do we know if there is any purchase invoice of any kind in any of George's records or files or anything listed in the Purdue University. Is it possible that there is a ledger somewhere with accounts receivable at the Miami Airport? It would be really interesting to find out if this be the case. Anyway, you might be on to something of this Ric. If Guerin Hydropress was a big thing, then most likely most of the big time plane body shops would have had it in their possesion and at any time, it would be possible to cut and form a piece of metal to fit to size. I'm curious to know if any of these alloy sheets are anywhere to be found in Miami???
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Rivet machines replaced hand riveting, and combined, the improved production techniques cut manufacturing time by 50 percent.
Machine riveting would be very precise. Unfortunately, the article does not say when Douglas began using machine riveting.
With Guerin "Hydropress" it makes you wonder during that time frame and with war in the foreground that one type of metal was used.
The type of metal did not change. From 1932 on, virtually all American all-metal aircraft, military and civilian, were made of 24ST aluminum.
Two things we might need to consider with more information on the patch is what kind of record keeping did George Putnam have in regards to the cost of having this done to the plane. Do we know if there is any purchase invoice of any kind in any of George's records or files or anything listed in the Purdue University. Is it possible that there is a ledger somewhere with accounts receivable at the Miami Airport?
No records of any kind have come to light with respect to the installation of the patch in Miami.
If Guerin Hydropress was a big thing, then most likely most of the big time plane body shops would have had it in their possesion and at any time, it would be possible to cut and form a piece of metal to fit to size. I'm curious to know if any of these alloy sheets are anywhere to be found in Miami???
While in Miami, NR16020 was hangared at Karl Voelter Inc., a small FBO offering "Sale -Service -School" at Miami Municipal Airport - certainly not a "big time plane body shop". The patch was probably installed in the Voelter hangar. I think the Guerin Hydropress is something that would only be found in an airplane factory.
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Just a note this web page shows archive holdings at HistoryMiami Museum, aviation papers predominantly from 1930-1955 including Miami International Airport (which was previously Miami Municipal Airport), of particular interest is that there are holdings in this collection related to Amelia Earhart but no details given. Might be worth a visit for a local TIGHAR member
https://www.historymiamiarchives.org/aviation-papers-circa-1920-1963
also in the Memphis Public Library archive a box of material related to Phoebe Omlie a woman prominent in aviation in the 1930s and 40s includes correspondence between her and Karl Voelter apparently in regard to a planned Amelia Earhart film, there might be something of interest there.
"Box Four
contains materials relating to a proposed Amelia Earhart film; the Ninety-Nines, Inc.; Helen
Richey; OX5; aviation magazines, newsletters, and articles; various personal documents; and
general correspondence with Louise Thaden, Phil Wendell, Robert McComb, Karl Voelter,
Glenn Buffington, and Roscoe Turner."
https://memphislibrary.contentdm.oclc.org/digital/collection/p13039coll1/id/2601/
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Just a note this web page shows archive holdings at HistoryMiami Museum, aviation papers predominantly from 1930-1955 including Miami International Airport (which was previously Miami Municipal Airport), of particular interest is that there are holdings in this collection related to Amelia Earhart but no details given. Might be worth a visit for a local TIGHAR member
Jeff Glickman and I visited that collection when we were in Miami in 2014. Nothing helpful there.
BTW, Miami International was not previously Miami Municipal. Miami Municipal ceased operations in 1954. It's now Amelia Earhart Park. MIA was originally Miami City Airport and later merged with adjacent Pan American Field and Miami Army Airfield to become Miami International.
also in the Memphis Public Library archive a box of material related to Phoebe Omlie a woman prominent in aviation in the 1930s and 40s includes correspondence between her and Karl Voelter apparently in regard to a planned Amelia Earhart film, there might be something of interest there.
The film seems to have been a 1974 production involving Shirley Maclaine.
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This is an update on what I’ve been doing to test the hypothesis that 2-2-V-1 is from the C-47A that crashed on Sydney Island Dec. 17, 1943.
As shown in the attached illustrations, I’ve assigned an alpha-numeric designator to each rivet hole on 2-2-V-1 ( see “hole numbers.jpg”). After precisely measuring distances on the artifact with adhesive measuring tape, I’ve plotted each hole on a schematic in Adobe Illustrator to a tolerance 1/32”. The result is a far more accurate picture of the rivet pattern than we have ever had.
Major take-aways:
• The spacing of the rivet lines as shown in a 1992 issue of TIGHAR Tracks (https://www.tighar.org/Publications/TTracks/1992Vol_8/0803.pdf) is not precise. The paper template of 2-2-V-1 used by Tom Palshaw is based on the 1992 measurements. The differences, while not huge (see “Actual v template”.jpg ) are significant when measuring precise alignment with the pattern on the C-47 wing. Palshaw’s template appears to fit the C-47B wing but it does not accurately reflect the artifact.
• The pitch of the small rivets in all four lines - a total of 93 rivets - is unfailingly precise at exactly one inch, except in one instance. The space between holes C14 and C15 is 1/16” short (see “#3 pitch anom.jpg”). Hole C14 is “stretched” vertically. I don’t see how the two anomalies have anything to do with each other. The pitch precision of 99% of the small rivets suggests the use of a jig or template, but the anomaly argues against a jig, so the small rivet holes appear to have been hand-drilled using a template which apparently slipped in one instance. This would seem to be more likely in an expedient repair rather than during factory manufacture.
The vertically deformed hole is unusual - nearly all other holes are undeformed. The vertical deformation implies a tugging force. The bottom edge of 2-2-V-1 exhibits lateral tearing due to overload, i.e. tugging.
• The two top rivet lines (E and F) angle down left to right and are nearly, but not exactly, parallel to each other. The center rivet line (D) runs straight left to right. The lowest row of small rivets (C) is parallel to the center line (D).
• The large rivet holes along the bottom of the artifact (B) have a consistent pitch of 1 1/4” except between B5 and B6 where the pitch is 1 1/8” (an eighth of an inch short) and between B6 and B7 where the pitch is 1 11/16” (nearly half an inch too long).
• Perhaps more significantly, line B is actually two separate lines. Holes from B1 to B5 are in alignment, but at B6 the line jumps up 1/8” and continues straight to B14. There may, or may not, be a hole at B15. (see “Line B.jpg”)
• An “A” line of rivets is implied but no remnant of a hole is discernible so it’s not possible to know the distance between lines A and B.
Whether any of these features can be seen on the patch awaits Jeff Glickman's work with the 16mm film.
All of this is unlike anything I saw on the C-47A at Dover AFB and supports the hypothesis that 2-2-V-1 is a repair rather than factory construction.
Tom Palshaw was using an inaccurate template (my fault, not his) to compare 2-2-V-1 to the wrong airplane (a C-47B rather than a C-47A). The C-47A at Dover, 42-9284, is a different contract year than the plane that crashed on Sydney, 43-30739. For the best possible comparison to the C-47A that crashed on Sydney Island, we need to come as close as we can to apples-to-apples. We need to do a detailed examination and measurement of the relevant section on the wing of the closest surviving C-47A by tail number. We will be doing that later this winter.
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http://www.historymiami.org/wp-content/uploads/documents/update-v1-n6-3.pdf
I ran across this article the other night on Karl Voelter and Miami Airport. Its a very good article and talks alot about who Karl really was. His portion of the article starts on page 5, and page 12. After reading the article, I personally am convinced that the patch work done to the Electra wasnt done in a hurry per say. After reading Karl's profile, I'm convinced that his way of doing things had to be in top notch condition. After all he was in the Marines and he also flew planes and also raced them. However, it did mention the fact that what he had, was a "tin hangar". I don't know how to decipher that comment, but I assume it was all he had to work with! I also uncovered in the Air Commerce Bulletin of 1935-1937 ads that mentioned Karl Voelter Inc. and his aeronautical charts he had for sale. So I believe Mr. Voelter was a reputable man and did things the right way.
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Randy,
That's a good find and very interesting. I wonder if Mr. Voelter's descendants, if any, have kept any of his papers or other documentation which may shed light on May/June 1937.
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After reading the article, I personally am convinced that the patch work done to the Electra wasnt done in a hurry per say. After reading Karl's profile, I'm convinced that his way of doing things had to be in top notch condition.
I think the patch was probably fashioned and installed by Earhart's own mechanic, "Bo" McKneeley. He probably did the work in Voelter's hangar, but NR16020 was Bo's baby. He had been maintaining and performing modifications on the airplane for the past year. He was likely the one who installed the window the patch replaced. It doesn't make sense that he would outsource a last-minute repair.
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Ric, there is one thing I did forget to mention in my findings in the Air Commerce Bulletin was that in the 1935-1937 issues it has a section where planes that make changes and modifications have a certificate number of the change or work done. I found that very interesting. I did search those certain issues but did not see anything. Not saying its possible that a certificate number was issued on the Electra...but something to look further into!
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Randy, you're referring to a Supplemental Type Certificate (STC) (https://www.faa.gov/aircraft/air_cert/design_approvals/stc/).
"A supplemental type certificate (STC) is a type certificate (TC) issued when an applicant has received FAA approval to modify an aeronautical product from its original design."
The window added to the door and the window installed in the lavatory area on NR16020 in January 1937, and the subsequent replacement of the lavatory window with a patch in June 1937 required what is known as a One-Only STC (https://www.faa.gov/aircraft/air_cert/design_approvals/stc/stc_variants/).
"A One-only STC may be issued for a particular aircraft, identified by make, model, and serial number. A one-only STC cannot be amended and the holder is not eligible for production approval."
The Civil Aeronautics Board (now FAA) file on NR16020 contains no STCs for those modifications. If they existed, that's where they would be. The modifications were apparently done without government approval or inspection.
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http://www.specialbooks.com/last_flight.htm
Ran across this article from the book "Last Flight". I dont know Ric or other Tighars if any of you have read it, but I found several things of interest. In the article on day 4 of Amelia's flight to Miami, it talks about how the landing gear was tampered with after someone scratched their initials into the landing gear. This is the first I've heard of this...anyone else? In the article it shows the landing gear being inspected. It also shows the inspector in the photo holding a piece of sheet metal. Could our artifact have come from this in due time? Also, in between this date and the 30th and 31st it shows where the Electra's antenna was moved several times to accomodate Amelia's need for better radio performance. On the 30th it talks about how the window was skinned over and how odd it felt to others that this was done in the first place! Thought you might like to see this.
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Ran across this article from the book "Last Flight".
Randy, you seem to be under the impression that the article is quoting from 1937. It isn't.
The web page is promotion for "the forthcoming book" Last Flight of Amelia Earhart. Three things should set off alarm bells:
• It's a product of Douglas Westfall's Paragon Agency.
• It appears to be the work of Nicole Swinford, author of Amelia Earhart's Last Photo Shoot. Swinford wrote an entire book around the mistaken notion that a piece of movie film taken during a March 1937 photo op prior to the first world flight attempt was taken in May.
• No sources are cited.
In the article on day 4 of Amelia's flight to Miami, it talks about how the landing gear was tampered with after someone scratched their initials into the landing gear. This is the first I've heard of this...anyone else?
Yes, that apparently happened. When McKneeley inspected the gear after Earhart's hard landing in Miami he discovered the initials scratched into the strut. He consulted Lockheed and they said if the scratches were shallow enough to be polished out if was of no concern. McKneeley was able to polish them out. The only source for this is Elgen Long's book (page 123). He attributes the information to an interview he did with McKneeley in 1975.
In the article it shows the landing gear being inspected.
No it doesn't. The caption on the photo is wrong. That looks like McKneely, but he's nowhere near the strut. He's looking at the accessories at the rear of the engine. See photo below.
It also shows the inspector in the photo holding a piece of sheet metal.
He is not holding a piece of metal.
Also, in between this date and the 30th and 31st it shows where the Electra's antenna was moved several times to accomodate Amelia's need for better radio performance.
Not true. The antenna mast for the dorsal vee was moved forward on the (bad) advice of Joe Gurr before the plane left Burbank. In Miami, Pan Am's radio technician Michelfelder experimented with shortening the feed from the antenna to the transmitter.
The web page also repeats the fiction that the "trailing ball" (aka trailing wire) antenna was removed in Miami.
Worse yet, it makes the bizarre claim that the loop antenna was removed after a six-hour test flight on May 31 and re-installed the next morning prior to departure for San Juan. Never happened.
On the 30th it talks about how the window was skinned over and how odd it felt to others that this was done in the first place! Thought you might like to see this.
Yes. Thanks. There is no quote from anyone about how anyone felt. Any information Swinford has about the skinning over came from TIGHAR. Incredibly, rather than show an actual photo of the Electra with the patch, she used a March 18 photo of the Electra in the hangar at Wheeler Army Air Field in Hawaii and photoshopped out the navigator's window. See below.
Nothing in the Paragon webpage or the forthcoming book can be trusted.
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TIGHAR Artifact 2-2-V-1 did not come from a C-47. The Wing Plating diagram in the C-47 structural repair manual shows the skin thickness in the entire are where the rivet pattern allegedly matches 2-2-V-1 is .028". The artifact's skin thickness is .032".
Tom Palshaw measured the skin thickness on the C-47B wing at the New England Air Museum as .032 using a micrometer at the edge of the skin. .004" is an easy error to make. It's a small but important discrepancy. The NTSB lab, Professor Eager at MIT, and the Massachusetts Materials Research metallurgical lab all measured 2-2-V-1 as .032".
The C-47 manual dates from September 1942 and was updated in 1945. There is no indication that the basic structural components of the wing were changed.
With this new information, the rivet pattern on the C-47 wing, although remarkably similar to the artifact, becomes another of the crazy coincidences we sometimes encounter (think sextant box).
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Tom Palshaw measured the skin thickness on the C-47B wing at the New England Air Museum as .032 using a micrometer at the edge of the skin. .004" is an easy error to make.
Is the fact that the manual specifies a .004 thinner skin the only reason to think a measurement error was made?
A few possibilities for there being an error or not:
1. Measuring the skin just aft of the suspected area. The skin there is .032 per the manual.
2. Not a flush fit of the micrometer on the skin.
3. Micrometer calibration problem.
3. The correct area was measured accurately and is .032. And there is some reason we don’t know yet for this C-47’s skin being different from the repair manual.
Based on the other “crazy coincidences” in the rivet pattern, and that Tom said he measured the skin as .032, I think the actual skin thickness on the C-47B wing at the New England Air Museum needs to be confirmed by some better means, at least explained better. In an earlier post I suggested that the skin measurement be photographed. This is so the viewer can see if the correct area was measured and best practices followed. Including photos of measuring known samples of .032 to prove the micrometer used is calibrated and accurate. Of course an independent lab would be preferable. Three Independent sources confirmed 2-2-V-1 thickness.
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Is the fact that the manual specifies a .004 thinner skin the only reason to think a measurement error was made?
A few possibilities for there being an error or not:
1. Measuring the skin just aft of the suspected area. The skin there is .032 per the manual.
2. Not a flush fit of the micrometer on the skin.
3. Micrometer calibration problem.
Those are all reasonable possibilities. I know from experience that measuring skin thickness with a digital micrometer is difficult and frustrating. Measure three times and get three different answers. With a little confirmation bias you can get any result you want.
3. The correct area was measured accurately and is .032. And there is some reason we don’t know yet for this C-47’s skin being different from the repair manual.
I don't see how that could be a reasonable possibility.
• Skin thicknesses are not optional. They are part of the design certificated by the government. They can only be changed by official revision. As shown on the second page of the manual, page 6 (Wing Plating) was not revised. It is not reasonable to suggest that some C-47s were manufactured with different wing plating.
• It is standard aircraft repair practice that a repair patch be made of the next thicker sheet than the surrounding skin, but the C-47B wing is not patched and the C-47A that crashed on Sydney was a new airplane on its way to its first assignment. Its wingtip was repaired after striking a guy wire on Canton, but the wingtip is a long way from the area in question.
• The illustration Palshaw sent me (attached) showing where the rivet pattern fits is on page 7 of the C-47 structural repair manual, so Palshaw apparently has that manual. Why did he measure the skin thickness with a micrometer instead of simply looking at the Wing Plating diagram on the previous page? If he did look at the Wing Plating diagram, why didn't he acknowledge the discrepancy between his measurement and the specifications?
Based on the other “crazy coincidences” in the rivet pattern, and that Tom said he measured the skin as .032, I think the actual skin thickness on the C-47B wing at the New England Air Museum needs to be confirmed by some better means, at least explained better. In an earlier post I suggested that the skin measurement be photographed. This is so the viewer can see if the correct area was measured and best practices followed. Including photos of measuring known samples of .032 to prove the micrometer used is calibrated and accurate.
By crazy coincidence, I'll be at the New England Air Museum on Thursday. We're doing 3D laser scanning of their Lockheed 10. I'll take another look at the C-47B wing section and see if I can take a micrometer measurement of the skin thickness. Mark Smith will also be there so we can video/photograph whatever we're able to do.
Of course an independent lab would be preferable. Three Independent sources confirmed 2-2-V-1 thickness.
Let's see how it goes.
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Wouldn't hurt to ask if they have any plexiglass scraps lying around :)
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Wouldn't hurt to ask if they have any plexiglass scraps lying around :)
I'll ask. Also, I've heard from Tom Palshaw.
"I just heard that TIGHAR will be visiting NEAM to do research on the Lockheed 10.
I wanted to let you know up front that I support the research. Whenever facts are in question, the only solution is to do the research. You had earlier said that others can have differing opinions but should be able to back them up with facts. I agree."
I told him I hope he'll be able to be there. I also sent him a copy of the C-47 Hull Plating diagram.
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On Friday 1/24, Duane Redding, Senior Engineer - Advanced Projects at HAYND, LLC, did 3D Laser Scanning of 2-2-V-1 and Lockheed 10 c/n 1052 at the New England Air Museum. More on that another time.
On Thursday 1/23, I spent a couple hours with Tom Palshaw discussing his theory that 2-2-V-1 came from the wing of a C-47. Tom is not a TIGHAR critic. He respects and admires TIGHAR's scientific approach to historical investigation. I respect and admire his expertise in aircraft restoration. Tom and I have known each other for many years. We are friends. He reads the Forum. Tom had written up answers to the questions raised here and offered some questions of his own (attached below).
I will reply in a follow-up posting.
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Replying to Tom Palshaw's questions:
1. What is the production tolerance for ALCOA 24S .028?
The ALCOA publication "Aluminum in Aircraft", 1941a edition, includes Table 20, Commercial Thickness Tolerances for Sheet and Plate. (see attached) The table does not list .028 sheet as a standard thickness, but production tolerances for .025" and .032" are shown to be .0025".
2. What are the thickness differences between bare .028 and ALCLAD .028? ... If bare .028 aluminum measures 0.028" thick, does ALCLAD .028 measure 0.030"?
Table II in "Aluminum in Aircraft" list the Allowable Bearing Strength of Aluminum Alloy Sheet. (see attached)
Again, 028" sheet is not listed, but the bearing strength of .025' and .032" ALCLAD 24S sheet is less than the bearing strength of bare .025' and .032" 24S sheet, so the core 24s component of the ALCLAD sheet is thinner. The answer is no. Bare sheet and ALCLAD sheet measure the same. When you order a sheet of .028" 24S you get a sheet that measures .028" whether or not it's ALCLAD. The plus or minus .0025 production tolerance means a .028 sheet might measure as much as .0305" but it should not measure .032" .
3. What explains the difference between the wing skin on the DC-3 (43-1973) on display and the same skin on the C-47B wing (43-49197).
The aircraft on display, 43-1973, was built as a commercial aircraft under a DC-3 type certificate. It received the 43-1973 tail number when it was "drafted" into the Army and became a C-49. The C-47B was built as a military aircraft under a C-47 type certificate. As you explained too me, the skin you measured for thickness is on the DC-3. You didn't measure the skin on the C-47B wing because you could't get to that skin.
Bottom line: There are visible differences between the wing structure of the DC-3 and the C-47. If your measurement of the DC-3 skin thickness is correct, and the Plating Diagram for the C-47 wing is correct, the skin thickness in the wing section is among the differences.
In any case, I see no reason to think the skin thickness on the wing of the C-47A that crashed on Sydney Island was .032"