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Author Topic: FAQ: Cowls on NR16020  (Read 13183 times)

JNev

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FAQ: Cowls on NR16020
« on: April 25, 2012, 10:40:28 PM »

Quote
The ugly rivets refer to the prominent type of cowling fixings that Earhart's Electra was fitted with - those appear in contemporary photos...

Personally, pre-war AD 456 Brazier head rivets are lovely, domed things to me when well affixed (as in the pictures), while 'ugly' sounds like something quite else.  By way of a bit of contrast, I find the common AD 470 'universal head' rivet of WWII and later to be slightly less elegant: it has a slightly flattened 'top' and a bulkier 'dome', but was more easily handled in mass production and has slightly improved stress qualities.  All IMHO, of course - which is sort of the point... YMMV (this is a most subjective term, this 'ugly rivet' thing).

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...while the yellow interior sounds to me to be none other than Zinc Chromate.

'Sounds' like that to me, too - but the point would be "did AE's airplane have yellow zinc chromate applied in the area described?" 

Not sure we can know whether NR16020 had yellow, green or no zinc chromate applied (it most assuredly would not in today's EPA rules in California - where even hamburger cartons seem to come with cancer warnings...) - but it is was not and is not universally the practice to do that in civilian, land-based planes.  In my experience, while certainly not unheard of in civilian use, it is a more common thing among naval and other military types. 

Point being we are far from a respectable conclusion as to the meaning of that particular observation and it probably does little, if anything, to draw us to a conclusion about the wreck having been that of NR16020.  I'd bet the aluminum was silver, more or less too.  So was the aluminum 'skin' found on Niku... ;)

LTM -
- Jeff Neville

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« Last Edit: July 16, 2012, 08:17:56 PM by J. Nevill »
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Malcolm McKay

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Re: Cowls on NR16020
« Reply #1 on: April 26, 2012, 12:37:43 AM »

Quote
The ugly rivets refer to the prominent type of cowling fixings that Earhart's Electra was fitted with - those appear in contemporary photos...

...By way of a bit of contrast, I find the common AD 470 'universal head' rivet of WWII and later to be slightly less elegant: it has a slightly flattened 'top' and a bulkier 'dome', but was more easily handled in mass production and has slightly improved stress qualities.  All IMHO, of course - which is sort of the point... YMMV (this is a most subjective term, this 'ugly rivet' thing).

Quote
...while the yellow interior sounds to me to be none other than Zinc Chromate.

'Sounds' like that to me, too - ...In my experience, while certainly not unheard of in civilian use, it is a more common thing among naval and other military types. 

Point being we are far from a respectable conclusion as to the meaning of that particular observation and it probably does little, if anything, to draw us to a conclusion about the wreck having been that of NR16020.  I'd bet the aluminum was silver, more or less too.  So was the aluminum 'skin' found on Niku... ;)

LTM -

Sorry but you are showing that you have not read the material on the East New Britain claim properly - also have a look at photos of the early examples of the Electra. The front of the engine cowl is quite flat unlike the later forms which had a more rounded shape. The "ugly" term I am using is how the soldiers who found the wreck in 1945 described it. Personally I think they just meant that they were prominent rivets as distinct from later flush types, or they may have thought them ugly - certainly the cowl as used on the Earhart Electra is not the most aerodynamically efficient. As for your discourse on the aesthetic qualities of rivets you are welcome to think whatever you like about them - but I suspect that opinion is irrelevant to the issue at hand.

The natural explanation given the historic use of Zinc Chromate is that if the interior of the cowl was seen to be yellow then that colour would be Zinc Chromate. So if that's what the soldiers claim so maybe it is yellow and that would be explained logically as ZCY. However it doesn't mean that it is Earhart's aircraft anymore than the evidence so far presented to claim that Earhart and Noonan were on Nikumaroro hasn't clearly proved they were there. We keep coming back to these claims about aircraft skin found on Nikumaroro, now faith is a wonderful thing but I actually would like to see a little more hard evidence.

As for the enhanced photo - are TIGHAR positive that it shows an undercarriage leg or is this still not determined. One can read the statement either way. It will be difficult to take seriously if it is another "might be, possibly be" situation. Too many leaps of faith.
« Last Edit: July 16, 2012, 08:14:57 PM by J. Nevill »
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Malcolm McKay

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Re: Cowls on NR16020
« Reply #2 on: April 26, 2012, 07:10:33 PM »


Quote
...also have a look at photos of the early examples of the Electra. The front of the engine cowl is quite flat unlike the later forms which had a more rounded shape.


Not sure what the 'shape' of the cowl has to do with the description of the rivets...

All the best,

The cowl on the first Electras (like Earhart's) had a flat front - the "ugly" rivets are the small cluster of fasteners on the inner front section of the cowl which hold the sections together. They are quite prominent, unlike on later cowls which being more aerodynamically formed had flush types.

I hope that provides the clarification.  :)
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Malcolm McKay

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Re: Cowls on NR16020
« Reply #3 on: April 26, 2012, 09:26:34 PM »

A further note on the Electra's engine cowls. The model that Earhart used had a cowled radial engine however the cowl itself was just a basic metal cover with a flat front and had very little aerodynamic refinement. By the time the Electra came into service there were two cowl designs which were in general use but which for some reason or other the Electra didn't have. The first was the Townend ring developed in Britain by Dr Hubert Townend and the second was a refinement of the principle developed by NACA in the US.

http://en.wikipedia.org/wiki/Townend_ring

http://en.wikipedia.org/wiki/NACA_cowling

The purpose of these two cowl types was not simply streamlining, which they did achieve, but more importantly that by aerodynamic means they created an airflow stream around the cylinder heads of a radial engine (which is an air cooled engine) so that the cooling effects of the airflow was enhanced. Previously air cooled radials were left uncowled and while this might at first glance appear to be an effective means to allow air past the cylinder heads to cool them it was in reality not all that effective because the combination of the propellor generated air flow and the tendency of the bluff front of the radial to create an aerodynamic wall which drove the air up and over rather than through the gaps between the cylinders to cool them.

Later versions of the Model 10 Electra had a better cowling design closer to the NACA type.
« Last Edit: April 26, 2012, 09:29:57 PM by Malcolm McKay »
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JNev

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Re: Cowls on NR16020
« Reply #4 on: April 27, 2012, 06:46:21 AM »

Why not just look at what AE's Electra did have for cowlings?

The NACA-styled cowls were a common type on U.S. aircraft at the time and had emerged around 1927.  They are similar to as on the Electra as far back as Kelly Johnson's initial aero work on the design (note the single tail on the model - which he had Lockheed change to the twin tails we see on the productin airplanes).  By your descripton of a 'flat' section it seems you are noting the rather prominent 'lip' on NR16020.  Here is an L10A that at first glance seems to have what appears to be a more refined shape - but compare closely: the color photo / orange paint tend to sharpen the lines - the 'difference' may be an illusion.  A dig into L10 evolution might tell more though.

I agree that if ever found, the detailed shape of the New Britain wreck's cowlings could very well tell us something about the airplane's heritage.  I'm not sure I follow that we gain enough specifics from the soldier's recollections of what he saw to be that definitive, however, but YMMV.

The review of the evolution of the aerodynamic cowling is quite interesting, but I am not sure it's completely relevant to a search for NR16020; the direct photo evidence of what was actually on AE's airplane seems very relevent. 

LTM -
- Jeff Neville

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« Last Edit: April 27, 2012, 07:15:55 AM by J.C. Neville »
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Tom Swearengen

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Re: Cowls on NR16020
« Reply #5 on: April 27, 2012, 07:05:47 AM »

there are some pics of the Electra at various stages of the world flight. The cowlings were 'probably' changed during the repair after the Luke field incident. I dont have any close up's of the cowling once the flight started.
Tom Swearengen TIGHAR # 3297
 
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Malcolm McKay

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Re: Cowls on NR16020
« Reply #6 on: April 27, 2012, 07:10:11 PM »

Here is an L10A that at first glance seems to have what appears to be a more refined shape - but compare closely: the color photo / orange paint tend to sharpen the lines - the 'difference' may be an illusion.  A dig into L10 evolution might tell more though.
LTM -

That is an Electra fitted with the style of cowl found on the T6 which is a much later innovation. But that aside the actual cowl shape and construction was one of the things mentioned by Billings in his claims for the East New Britain hypothesis. As I am at constant pains to point out I am not supporting that hypothesis over the Nikumaroro one or, for that matter, any of the other two. All I am seeking to do is evaluate all the arguments one against the other.

The Earhart Electra has the early type cowl with the prominent set of rivets near the inner lip as does, it is claimed, the New Britain wreck. But as the New Britain wreck has not been located then at present we cannot say for certain that the recollections of the members of the Australian military patrol that found it are correct (something I told Billings which met with the same reaction as my questions here - everyone is a little partisan  :) ) as neither can we say until a wreck is located somewhere around Nikumaroro if that claim is correct. I am quite neutral in the matter.
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Malcolm McKay

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Re: Cowls on NR16020
« Reply #7 on: April 27, 2012, 08:45:48 PM »

As a highly modified Electra 10E, I assure you there was not another equipped like her in the world. Lets find the new Britain wreckage and look in the fuselege for the extra fuel tank plumbing. Thats a start.
Tom

Hello Tom

If you read my last post closely you will see where I said

The Earhart Electra has the early type cowl with the prominent set of rivets near the inner lip as does, it is claimed, the New Britain wreck. But as the New Britain wreck has not been located then at present we cannot say for certain that the recollections of the members of the Australian military patrol that found it are correct (something I told Billings which met with the same reaction as my questions here - everyone is a little partisan  :)  ) as neither can we say until a wreck is located somewhere around Nikumaroro if that claim is correct. I am quite neutral in the matter.

The final sentence in that is the key to how I feel vis a vis the four relatively sane hypotheses regarding Earhart and Noonan's disappearance. As in the discussion of the Nikumaroro hypothesis I can only work from what has been published as supporting evidence. Also because I am quite neutral in the matter I prefer to judge each on its merits. Currently, as I have said, conclusive evidence has not been found to give any single hypothesis the checkered flag. And because my obviously irritating neutrality and desire to assess the evidence as rigorously as I can (and that is not perfect I assure you  :) ) seems to provoke some strong reactions then I also am trying not to encourage those because in the end they are of no value.

I have engaged Mr Billings elsewhere in questions regarding the East New Britain hypothesis. I was as rigorous, or downright irritating (take your pick  ;) ) as I have appeared to be here. I have no intention of discussing that conversation here as that would be both impolite and seen by many, quite rightly, to be self-serving rather than germane. All I will say is that I wish someone would find the particular wreckage noted by the Australian patrol - that would provide an answer either way.

Regarding the Gilberts hypothesis, it also has strong attractions including the Vidal statement to support it, not to mention that as a larger group of islands it would make a good target. Quite possibly Earhart and Noonan could have come down down somewhere there - it is a vast ocean, and there are many small islands.

I have read Gary's arguments concerning the navigation problems and putative distances flown. But again there is nothing except informed conjecture to support them. Frankly I do not think we know enough about the final flight and what was happening in the aircraft to make any firm conclusions about at what point they may have turned back, if indeed they did. However lack of evidence proves nothing, but hard evidence proves everything so like everyone I hope that TIGHAR can put the mystery to rest this year.

Regards

Malcolm         
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Martin X. Moleski, SJ

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Re: Cowls on NR16020
« Reply #8 on: April 27, 2012, 09:21:05 PM »

A dig into L10 evolution might tell more ...

FWIW, I've uploaded the photos I took of an L10 A in Auckland, NZ, in 2003.

I have no idea where this airframe or cowling fits into the story.

I was interested in a different line of argument back then, hence the rather strange closeups of parts of the cowling.

LTM,

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« Last Edit: April 27, 2012, 09:25:48 PM by Martin X. Moleski, SJ »
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Martin X. Moleski, SJ

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Re: Cowls on NR16020
« Reply #9 on: April 27, 2012, 09:42:40 PM »

Dragged kicking and screaming from another thread:

Some photos showing the rivets around the engine cowling may be seen at History Detectives Report.
 which also discusses an artifact reputed to be a souvenir of the Luke field crash.

I'd like to know what efforts have been made to track down the tag, or even supporting documentation of the tag.
LTM,

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JNev

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Re: Cowls on NR16020
« Reply #10 on: April 28, 2012, 02:14:51 PM »


FWIW, I've uploaded the photos I took of an L10 A in Auckland, NZ, in 2003...


This looks like a fair match of a cowling to that in Marty's photo of the museum L10.  Might be useful in helping to understand what to look for.

Here is another - a close-up of a segmented cowling as-removed from the Electra after the crash at Luke Field - look in the lower-left corner of the picture.  It's a bit hazy, but it also shows some of the cross-section profile of the cowling 'lip' area.

LTM -
- Jeff Neville

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Chuck Varney

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Re: Cowls on NR16020
« Reply #11 on: April 28, 2012, 03:14:40 PM »

I’ve attached two photos from the Purdue collection that show the port cowl and rivet detail on NR16020. One was taken prior to the first world flight; the other during the second world flight.

Links to photos:
Port cowl rivet detail, first world flight
Port cowl rivet detail, second world flight

Chuck
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Jeff Victor Hayden

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Re: Cowls on NR16020
« Reply #12 on: May 03, 2012, 04:56:32 PM »

Having researched Garys (and others) calculations regarding the PNR this discussion/debate would seem to be going nowhere. Unless they got towed back to New Britain there is very little chance of this wreckage having once been in the vicinity of Howland Island.
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Jeff Victor Hayden

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Re: Cowls on NR16020
« Reply #13 on: May 04, 2012, 07:44:03 AM »

The rivet patterns as shown in the images Chuck posted would be useful for identification purposes on any wreckage found (anywhere!) ;)
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