Advanced search  
Pages: 1 2 [3] 4 5 ... 11   Go Down

Author Topic: Grand Rapids trip (2-2-V-1)  (Read 132108 times)

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5503
  • "Do not try. Do or do not. There is no try" Yoda
Re: Grand Rapids trip
« Reply #30 on: January 27, 2014, 08:36:05 AM »

I was only speculating Tim but I don't think you are right about no skin behind the engine.

There is a massive firewall behind the engine.  The wheel well is under the nacelle, behind the firewall.
But none of this is anywhere near where we think the artifact came from.
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5503
  • "Do not try. Do or do not. There is no try" Yoda
Re: Grand Rapids trip
« Reply #31 on: January 27, 2014, 08:37:02 AM »

I'm not a materials expert, but I would expect TIGHAR is well on the way to finding one to contribute to the overall body of knowledge.

Trust me.   ;D
Logged

Greg Daspit

  • TIGHAR member
  • *
  • Posts: 732
Re: Grand Rapids trip
« Reply #32 on: January 27, 2014, 09:09:58 AM »

I was only speculating Tim but I don't think you are right about no skin behind the engine.

There is a massive firewall behind the engine.  The wheel well is under the nacelle, behind the firewall.
But none of this is anywhere near where we think the artifact came from.

I understand the artifact is suspected of being located in the belly, roughly opposite the cabin door. The water may have just come blasting thru the cabin door opening.
In reply 22, I also referred to  an image in the Glickman debris field that may have failed in the same way as the artifact may have failed.
The picture from the Purdue archives has 5 pulleys in that same area as the wing’s  leading edge behind the engine. There is a pulley shape next to the Glickman Debris Field “fender” shape and this shape has evidence of holes like the leading edge of the wing. I was suggesting the possible “fender’ shape could be a leading edge of a wing that kept its shape due to fluid pressure on it, similar to what may have happened to the artifact.
Apologies  if I got off topic
3971R
 
« Last Edit: January 27, 2014, 12:08:28 PM by Greg Daspit »
Logged

Greg Daspit

  • TIGHAR member
  • *
  • Posts: 732
Re: Grand Rapids trip
« Reply #33 on: January 27, 2014, 10:22:02 AM »

Sketch attached to show some possiblities/ speculation
(edited to correct 2-2-V-1 labeled and location)
3971R
 
« Last Edit: January 27, 2014, 12:50:26 PM by Greg Daspit »
Logged

Jon Romig

  • TIGHAR member
  • *
  • Posts: 86
Re: Grand Rapids trip
« Reply #34 on: January 27, 2014, 11:44:45 AM »

The Missing Rivets:

I have trouble understanding why all the smaller rivets are missing and the artifact shows no damage around the rivet holes. If the piece is blown off the aircraft frame (or off stiffeners), and there is no damage from rivet pull-through on the artifact, then every single rivet must have instantaneously reverted to nearly its original diameter, pulled through the frame, and fallen off. This seems somehow unlikely to me.

Why should the rivet pull through the frame, when the artifact must have been the lighter gauge material? Is the non-factory end of the rivet so much weaker - how does that align with the overall design strength for the rivets, which would mandate a rivet design where the two ends have near equal strength?

Is it possible that we are not looking at holes for rivets used on aircraft skin, but for some other use, where another rivet type (like a split head rather than a compressed head) may have been used?

Or that the holes were not for rivets at all, but rather for something else (tacks, nails, screws, thread, ventilation, RF, light, glue, etc.)? I've drilled plenty of 3/32 holes in my days for things other than rivets.

Jon
Jon Romig 3562R
 
Logged

Jon Romig

  • TIGHAR member
  • *
  • Posts: 86
Re: Grand Rapids trip
« Reply #35 on: January 27, 2014, 11:57:53 AM »

The Missing Rivets:

I have trouble understanding why all the smaller rivets are missing and the artifact shows no damage around the rivet holes. If the piece is blown off the aircraft frame (or off stiffeners), and there is no damage from rivet pull-through on the artifact, then every single rivet must have instantaneously reverted to nearly its original diameter, pulled through the frame, and fallen off. This seems somehow unlikely to me.

Why should the rivet pull through the frame, when the artifact must have been the lighter gauge material? Is the non-factory end of the rivet so much weaker - how does that align with the overall design strength for the rivets, which would mandate a rivet design where the two ends have near equal strength?

Is it possible that we are not looking at holes for rivets used on aircraft skin, but for some other use, where another rivet type (like a split head rather than a compressed head) may have been used?

Or that the holes were not for rivets at all, but rather for something else (tacks, nails, screws, thread, ventilation, RF, light, glue, etc.)? I've drilled plenty of 3/32 holes in my days for things other than rivets.

Jon

It would be useful to obtain the design pull-out strength of the rivet we presume would have been used, and calculate the total force (and PSI since we know the panel size) required to simultaneously pop them all at the same time.
Jon Romig 3562R
 
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5503
  • "Do not try. Do or do not. There is no try" Yoda
Re: Grand Rapids trip
« Reply #36 on: January 27, 2014, 12:25:25 PM »

Sketch attached to show some possiblities/ speculation
(edited to correct 2-2-V-1 labeled)

The hypothetical position of 2-2-V-1 is on the belly directly opposite the cabin door on the starboard side of the aircraft.
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5503
  • "Do not try. Do or do not. There is no try" Yoda
Re: Grand Rapids trip
« Reply #37 on: January 27, 2014, 12:33:48 PM »

If the piece is blown off the aircraft frame (or off stiffeners), and there is no damage from rivet pull-through on the artifact, then every single rivet must have instantaneously reverted to nearly its original diameter, pulled through the frame, and fallen off.

The rivets did not pull through.  The rivets apparently fractured at the base of the head.  The force of the water on the interior surface of the skin literally blew the heads off the rivets.  There is one surviving rivet that pulled through the stringer because it was improperly bucked.

Is it possible that we are not looking at holes for rivets used on aircraft skin

No.  There is no question that this is a section of aircraft skin. 

Logged

Chris Johnson

  • T5
  • *****
  • Posts: 1069
  • Trying to give a fig but would settle for $100,000
Re: Grand Rapids trip
« Reply #38 on: January 27, 2014, 02:10:23 PM »

How does this sheet differ from military aluminium from WW2?
Logged

JNev

  • T5
  • *****
  • Posts: 778
  • It's a GOOD thing to be in the cornfield...
Re: Grand Rapids trip
« Reply #39 on: January 27, 2014, 02:16:43 PM »

If the piece is blown off the aircraft frame (or off stiffeners), and there is no damage from rivet pull-through on the artifact, then every single rivet must have instantaneously reverted to nearly its original diameter, pulled through the frame, and fallen off.

The rivets did not pull through.  The rivets apparently fractured at the base of the head. 

Seems clearly the case - and not unusual for such small rivets (one good reason #3 (3/32") rivets are not normally used for primary structure: the skin's bearing strength far exceeds the rivet's in tension.

Here's some good information from FAA (see Section 4 - paragraphs 4-50 - 4-59 in particular) - which has changed very little over the many decades except for the introduction of modern fasteners like blind rivets, etc.  Note how relatively few 3/32" rivets were used per-inch in the artifact compared to the number recommended in table 4-9, for instance.  This suggests IMHO that the artifact's intermediate rivets were for very light secondary bracing, or done by an unknowing novice if for primary structure (can you say i-d-i-o-t).

Quote
The force of the water on the interior surface of the skin literally blew the heads off the rivets.  There is one surviving rivet that pulled through the stringer because it was improperly bucked.

Granted, whatever the force that was applied was from does appear to have been somewhat uniformally hydraulic in nature (not a pick-ax to the middle of the membrane, for sure) - there is plenty of water there, and we do know it can act with a great deal of force - even concentrated force, but many things are possible...

Is it possible that we are not looking at holes for rivets used on aircraft skin

Quote
No.  There is no question that this is a section of aircraft skin.

I certainly agree - and that of a pre-WWII vintage as TIGHAR has pointed out.
- Jeff Neville

Former Member 3074R
 
« Last Edit: January 27, 2014, 02:23:04 PM by Jeffrey Neville »
Logged

Chris Johnson

  • T5
  • *****
  • Posts: 1069
  • Trying to give a fig but would settle for $100,000
Re: Grand Rapids trip
« Reply #40 on: January 27, 2014, 02:28:30 PM »

What am I missing, what makes it 100% non military pre WW2 vintage?
Logged

JNev

  • T5
  • *****
  • Posts: 778
  • It's a GOOD thing to be in the cornfield...
Re: Grand Rapids trip
« Reply #41 on: January 27, 2014, 03:56:35 PM »

What am I missing, what makes it 100% non military pre WW2 vintage?

I don't know that it can be said that it is "100% non military", but as to "pre WWII vintage" -

The way the metal is marked, as said here (and quoted below, in excerpt, emphasis added) at the very least strongly suggests pre-war, certainly consistent with metal markings of Earhart's era -

Quote
...The aircraft was of all-metal construction and was manufactured in the United States, probably before 1939. The surviving rivet is an AN 455 AD 3/3. The head style, known as the “brazier” head, was replaced in most applications by the “universal” head (AN470) sometime after 1940. The letters “AD” noted on the exterior (convex) surface are the last two letters in the word ”ALCLAD” which was stamped onto the aluminum in red ink at the time of manufacture by Alcoa Aluminum as part of the product labeling. Complete examples of this same size and style of lettering (ALCLAD 24S T3) have been noted on aluminum used in repairs or modifications to two surviving Lockheed 10s: c/n 1015, recently rebuilt as a replica of Earhart’s aircraft and currently registered NX72GT, and c/n 1052 in the New England Air Museum collection. Similar labeling has also been found on a small patch on the nose of a Douglas C-47 in the Dover AFB Museum collection. The font, or type style, of the lettering does not appear to match any of the styles used by Alcoa for aluminum manufactured during or after World War II. The fact that the lettering is not aligned with the grain of the metal indicates that the labeling was hand-stamped, a practice replaced by rolled-on labeling when aluminum production boomed after 1939.

As has been said - none of this makes the piece a 'smoking gun', but it is somebody's rusty pistol and it is consistent with something one could reasonably expect to find on the Electra. 

TIGHAR seems to have a good idea 'where from' if from the Electra, I happen to have my own notion of that possibilty (merely a different area of the same airplane) as many have seen I'm sure.  I've certainly not spent the time pouring over metal and rivets on a real Electra that TIGHAR has, of course.  Either way it would be awfully nice to find a 'fit' if it can be done.  That metal can tell a lot if it's its figurative tongue can be loosened...
- Jeff Neville

Former Member 3074R
 
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5503
  • "Do not try. Do or do not. There is no try" Yoda
Re: Grand Rapids trip
« Reply #42 on: January 27, 2014, 03:58:31 PM »

What am I missing, what makes it 100% non military pre WW2 vintage?

Nobody said it's not military.  Both pre- and during WWII the aluminum used in civil and military aircraft was identical. 
What makes it not WWII is the use of small 3/32 rivets in primary load-bearing contraction.  As Jeff pointed out, you won't see that on any American WWII aircraft.  Also, the style of rivet (AN455AD 3/3 or AN456AD 3/3 flat brazier head) was largely obsolete by WWII.  We can say with some certainty that the aircraft this skin came from was pre-WWII vintage - and when you can say that about an artifact that was found on Gardner Island you've said a mouthful.
Logged

Ric Gillespie

  • Executive Director
  • Administrator
  • *
  • Posts: 5503
  • "Do not try. Do or do not. There is no try" Yoda
Re: Grand Rapids trip
« Reply #43 on: January 27, 2014, 04:01:36 PM »

I happen to have my own notion of that possibilty (merely a different area of the same airplane) as many have seen I'm sure.

I'm certainly open to other suggestions.  The tricky thing is finding a span of .032 skin that long (24 inches) with no crossing line of rivets.
Logged

John Ousterhout

  • T4
  • ****
  • Posts: 487
Re: Grand Rapids trip
« Reply #44 on: January 27, 2014, 05:45:22 PM »

Were the wheel wells lined?  I couldn't find any photos with an appropriate view.  (I'm also sure that you've already looked into it.)
Cheers,
JohnO
 
Logged
Pages: 1 2 [3] 4 5 ... 11   Go Up
 

Copyright 2019 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