Advanced search  
Pages: 1 2 [3]   Go Down

Author Topic: 2-2-V-1 wing panel comparisons  (Read 8741 times)

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5804
  • "Do not try. Do or do not. There is no try" Yoda
Re: 2-2-V-1 wing panel comparisons
« Reply #30 on: December 30, 2019, 09:07:21 AM »

Randy, you're referring to a Supplemental Type Certificate (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.
"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.   
Logged

Randy Conrad

  • TIGHAR member
  • *
  • Posts: 378
Re: 2-2-V-1 wing panel comparisons
« Reply #31 on: January 04, 2020, 02:25:09 AM »

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.
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5804
  • "Do not try. Do or do not. There is no try" Yoda
Re: 2-2-V-1 wing panel comparisons
« Reply #32 on: January 04, 2020, 09:28:29 AM »

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. 


« Last Edit: January 04, 2020, 09:30:19 AM by Ric Gillespie »
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5804
  • "Do not try. Do or do not. There is no try" Yoda
Re: 2-2-V-1 wing panel comparisons
« Reply #33 on: January 18, 2020, 02:12:26 PM »

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).

Logged

Greg Daspit

  • TIGHAR member
  • *
  • Posts: 760
Re: 2-2-V-1 wing panel comparisons
« Reply #34 on: January 20, 2020, 05:03:22 PM »

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.
3971R
 
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5804
  • "Do not try. Do or do not. There is no try" Yoda
Re: 2-2-V-1 wing panel comparisons
« Reply #35 on: January 21, 2020, 08:11:50 AM »

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.
Logged

Bill Mangus

  • TIGHAR member
  • *
  • Posts: 371
Re: 2-2-V-1 wing panel comparisons
« Reply #36 on: January 22, 2020, 09:28:15 AM »

Wouldn't hurt to ask if they have any plexiglass scraps lying around :)
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5804
  • "Do not try. Do or do not. There is no try" Yoda
Re: 2-2-V-1 wing panel comparisons
« Reply #37 on: January 22, 2020, 09:35:07 AM »

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.
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5804
  • "Do not try. Do or do not. There is no try" Yoda
Re: 2-2-V-1 wing panel comparisons
« Reply #38 on: January 26, 2020, 07:36:36 AM »

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.


Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5804
  • "Do not try. Do or do not. There is no try" Yoda
Re: 2-2-V-1 wing panel comparisons
« Reply #39 on: January 26, 2020, 09:12:24 AM »

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"
Logged
Pages: 1 2 [3]   Go Up
 

Copyright 2020 by TIGHAR, a non-profit foundation. No portion of the TIGHAR Website may be reproduced by xerographic, photographic, digital or any other means for any purpose. No portion of the TIGHAR Website may be stored in a retrieval system, copied, transmitted or transferred in any form or by any means, whether electronic, mechanical, digital, photographic, magnetic or otherwise, for any purpose without the express, written permission of TIGHAR. All rights reserved.

Contact us at: info@tighar.org • Phone: 610-467-1937 • Membership formwebmaster@tighar.org

Powered by MySQL SMF 2.0.15 | SMF © 2017, Simple Machines Powered by PHP