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Author Topic: Grand Rapids trip (2-2-V-1)  (Read 147798 times)

Jerry Germann

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Re: Grand Rapids trip
« Reply #90 on: January 31, 2014, 05:13:34 PM »

I believe it was reported that Earhart hit a small ridge of dirt at the end of the runway at Lae ( leaving dust hanging in the air for sometime). Damage due to this????
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Martin X. Moleski, SJ

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Re: Grand Rapids trip
« Reply #91 on: January 31, 2014, 05:29:15 PM »

I believe it was reported that Earhart hit a small ridge of dirt at the end of the runway at Lae ( leaving dust hanging in the air for sometime). Damage due to this? ???

The fact that "it was reported" does not mean that the report is reliable.

Ric Gillespie, "Forum Highlights":

Subject: Earhart's takeoff from Lae
Date: 8/2/00

>What we saw in the TIGHAR film clip was Bertie Heath's description of
>Earhart's take-off related to Pellegreno in 1967. Pellegrino, page 144 ---

He sat quietly a moment. "I wanted to see them off, but couldn't just stop working. The rest of that day I flew back and forth to the mines. The following day when returning from my first trip, I saw her silver plane moving slowly down the unpaved runway. It must have been 3000 feet long at that time. When her plane reached the road that had a high crest and ran across the runway near the seaward end, it bounced into the air, went over the drop off and then flew so low over the water that the propellers were throwing spray." He paused and took a sip of beer. "Always have a couple of beers every day." "She continued straight out to sea for several miles before climbing on course slowly. That was the last I saw of her." He thought for a moment. "The wind was calm and the dust from where she hit the crown of that dirt road didn't disperse quickly, just sort of hung there." 

Neither the takeoff film nor aerial photos of the airfield taken during that period show a dirt road crossing the runway. The film clearly shows that the rather abrupt rotation of the aircraft was the result of the pilot's actions, not an impact with a perturbation in the runway surface. Smoke from a brush fire on the far side of the runway also shows that the wind was not calm, and the only dust raised during the takeoff run was the puff described in my earlier posting. It occurs not at the moment of rotation as Heath alleges, but several seconds earlier in the takeoff run. The accurate parts of Bertie's recollections 30 years after the fact can be summarized as:
  • the plane was silver
  • the runway was unpaved
  • the runway was 3000 feet long at that time
  • always have a couple of beers every day
LTM,

           Marty
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Jon Romig

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Re: Grand Rapids trip
« Reply #92 on: January 31, 2014, 06:59:11 PM »

....
"The salt in moist air (found in the coastal areas) attacks the aluminum alloys. It is a common experience to inspect the rivets of an aircraft which has been operated near salt water and find them badly corroded.
....
The rivets may well have been weakened significantly by the environment the aircraft ended up in.

Re dissimilar metals:
If the rivets were weakened by corrosion caused by the galvanic action between two dissimilar metals, then I would expect to also see corrosion on the skin that they were in contact with. Or does only one of the two dissimilar metals experience the corrosion?

Jon

OK, OK, I did the research. Wikipedia says that in galvanic corrosion, the anodic metal will be corroded and the products of the corrosion will be deposited on the cathodic metal. So it seems that the artifact would show evidence of this process if it had occurred.

Conclusion: this type of corrosion did not occur to any great extent before the event that removed the rivets.

This is a nice piece of negative evidence that supports the primary narrative: given that we are pretty sure that these were dissimilar metals (the rivets and the skin), the artifact was not subject to extended exposure to the elements (including the necessary air) before the event that removed the rivets.

Jon
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« Last Edit: January 31, 2014, 07:00:58 PM by Jon Romig »
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Jon Romig

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Re: Grand Rapids trip
« Reply #93 on: January 31, 2014, 07:08:47 PM »

Assume a plane part is stuck in a groove at the steep edge of the reef like has been speculated. There is a storm.  Between the waves the plane may be exposed. (The water level of the wave below sea level about the same as the wave height above sea level) Then a fresh wave comes in. What happens to the water pressure of the next incomming wave in the groove?
And what happens to the velocity?

A much smaller wave arriving at low tide could experience considerable focusing in a reef groove, but smaller waves travel much slower. For example, a much smaller but still decent-sized 14' wave is only traveling at about 20 MPH. The geometry of the groove becomes increasingly important as you consider the even smaller waves that would be well-focused by the reef groove.

My sense is that reef grooves do not widen a lot towards deeper water, but I may be wrong.

Jon

Ric, could you describe the approximate shape and size of the reef grooves, especially the parts visible only at low tide? Do we have any photos?

Thanks!

Jon
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Jon Romig

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Re: Grand Rapids trip
« Reply #94 on: January 31, 2014, 08:18:00 PM »

Pressure

There have been occasional references to pressure (of water) in this thread. It is important to recognize that pressure (from the weight of the water column alone) is unlikely to have been the prime cause of the rivet failures. Consider:

Atmospheric pressure at sea level is 14.7 PSI.
The approximate pressure to cause the rivets to fail was 38 PSI minimum.
38 PSI is about 2.59 atmospheres.
Water pressure increases by 1 atmosphere for every 33' of depth. A water column tall enough to cause this pressure would be 85' high.

You could stand the Electra on its tail and fill it with water and never have near enough force to pop a panel off.

So we need to be looking at water in motion, unless we are modeling the event in a lab, where I believe that a static pressure experiment would be much safer than a 2' x 2' jet of water moving at 47 MPH....;-)

Jon
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« Last Edit: January 31, 2014, 08:23:30 PM by Jon Romig »
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Jerry Germann

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Re: Grand Rapids trip
« Reply #95 on: January 31, 2014, 09:01:48 PM »

Regarding artifact 2-2-V-1....As per the Al-clad lettering stamped in ink....the artifacts physical description state that the letters AD remain, on the convex/ rivet head bearing side....that said, can we conclude that if this panel was installed on the under belly or fuselage window opening , that this lettering would be visible looking upon the exterior of the plane? In 1937 the Electra had a value of roughly $80,000 dollars during the depression ...all photos give the appearance of it being a highly polished vessel.Photos of earhart and others captured under the wings and underbelly show mirror like quality reflections . During the reconstruction of the Electra after the Luke field incident, I came across photos of personal being shown x-raying the structural portions of the plane. To me it appears that quality and value was put into it's repair. With all this said, I wonder as to why lockheed or anyone ..(Miami) would place a panel in such fashion? It is my opinion ( though others may not agree) that any such repairs would have been buffed to like quality.....would Putnam and Earhart insist on this considering the electra's value? I don't know that answer. If this panel were part of the Electra, what panel /panels left unbuffed at the factory could provide the source of this artifact ? 
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Walter Runck

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Re: Grand Rapids trip
« Reply #96 on: January 31, 2014, 10:35:50 PM »

Pressure

There have been occasional references to pressure (of water) in this thread. It is important to recognize that pressure (from the weight of the water column alone) is unlikely to have been the prime cause of the rivet failures. Consider:

Atmospheric pressure at sea level is 14.7 PSI.
The approximate pressure to cause the rivets to fail was 38 PSI minimum.
38 PSI is about 2.59 atmospheres.
Water pressure increases by 1 atmosphere for every 33' of depth. A water column tall enough to cause this pressure would be 85' high.

You could stand the Electra on its tail and fill it with water and never have near enough force to pop a panel off.

So we need to be looking at water in motion, unless we are modeling the event in a lab, where I believe that a static pressure experiment would be much safer than a 2' x 2' jet of water moving at 47 MPH....;-)

Jon

You're correct Jon.  It doesn't matter how fast a stream of water is moving in air - it is at atmospheric pressure.  In fluid dynamics it's called free surface or open channel flow. 

It's easy to jumble the concepts of pressure and momentum when thinking about this stuff because it requires an external force to either balance (in the case of pressure) or change (in the case of momentum) the energy contained in the fluid.  The energy in an impacting wave that would blow out a window cover or other section of skin comes in the form of momentum, not pressure.  The reaction force is changing the momentum of the incoming stream by changing its direction.  It could be going as fast as ever, but if it is running parallel to the skin or some other surface, there is no net force on either the skin or the water.

While we're waiting for the lab work to come back, I found some flow modeling software that I'm going to play around with.  I'll post the results if I get anything that isn't obvious rubbish.
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Bill de Creeft

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Re: Grand Rapids trip
« Reply #97 on: February 01, 2014, 01:20:32 AM »

Jon...not sure i understand what you are saying...but the skin and rivets are not dissimilar metals; they are both aluminum...for that reason!'
They become "dissimilar" when located near a steel structure, for instance, particularly in water.

Have seen stainless steel skins over aluminum skins (in this case installed at exhaust ports for on board gas heaters to protect the aluminum skins ) that completely corroded away the aluminum on a seaplane exposed to salt water in normal operations...
But any airplane submersed in seawater with lots of steel structure and aluminum skin is going to result in deterioration...in fact it is a source of constant care and maintenance in normal operations around saltwater.
Engine cylinder heads are aluminum and the cyl. barrels are steel, and underwater the heads disappear in time when submerged as in the case of the radial engines on the Electra.

As to the earlier question by someone about the effect of loose or separated skin from the plane, as in the loss of a panel...it entirely depends on the location....A lost panel on the belly could be no worse than opening a camera hatch ( or a Bomb Bay)... on the wing, it could result in loss of lift on that side; resulting in a roll-over.

My feeling is it would not be a cause of the accident if the plane landed successfully...but if identified as apiece of the plane, would help identify the plane, obviously...
And therein lies the value.
I think this has been previously discussed.

Bill
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Tim Gard

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Re: Grand Rapids trip
« Reply #98 on: February 01, 2014, 02:05:31 AM »

It occurred to me that if water from an ebbing wave acted on one side of the skin, while water from a waxing wave acted on the other side of the skin the available forces might combine, doubling the available wave force .

/ Member #4122 /
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« Last Edit: February 01, 2014, 05:29:26 AM by Tim Gard »
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Ric Gillespie

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Re: Grand Rapids trip
« Reply #99 on: February 01, 2014, 07:29:31 AM »

Regarding artifact 2-2-V-1....As per the Al-clad lettering stamped in ink....the artifacts physical description state that the letters AD remain, on the convex/ rivet head bearing side

To be clear, no ink remains on the aluminum.  What we see is the imprint of the letters etched onto the surface. Not sure why the etching occurred on only some of the letters.

 
....that said, can we conclude that if this panel was installed on the under belly or fuselage window opening , that this lettering would be visible looking upon the exterior of the plane?

Forget the "window opening."  The rivet pattern is all wrong.  The repaired skin was installed with the labeling on the exterior surface.  No way to tell whether the ink of the labeling was then buffed off.

In 1937 the Electra had a value of roughly $80,000 dollars during the depression ...all photos give the appearance of it being a highly polished vessel.

They do?  The attached photo shows the plane at Burbank on May 20, 1937 - the day after it came out of the repair shop, being loaded for the departure of the second attempt.  I would call that normally shiny bare aluminum but not highly polished.  The second photo shows the c/n 1015 Finch/Kammerer replica now at the Museum of Flight.  That's what highly polished looks like.  Earhart's Electra never looked that good.

During the reconstruction of the Electra after the Luke field incident, I came across photos of personal being shown x-raying the structural portions of the plane. To me it appears that quality and value was put into it's repair. With all this said, I wonder as to why lockheed or anyone ..(Miami) would place a panel in such fashion?

The quality of the repairs was governed by Lockheed and the Bureau of Air Commerce inspectors, not Earhart and Putnam.  Official correspondence related to the repairs shows that it was a rush job.  Earhart was pushing to get a new letter of authorization from the State Dept. to do the second attempt.  On May 14,  Putnam told the State Dept. the plane had been thoroughly repaired but the day before, the inspector in California said that it would take another ten days to complete repairs and inspections.  In fact, the work was completed in five days.

It is my opinion ( though others may not agree) that any such repairs would have been buffed to like quality.....would Putnam and Earhart insist on this considering the electra's value? I don't know that answer.

The photos and documents provide the answer.  The repairs were a rush job and cosmetics do not seem to have been a major concern.  The skin in question may or may not have been buffed. No way to tell, and it doesn't matter.  The presence of the etched A and D on the artifact could well have remained on a buffed surface.
« Last Edit: February 01, 2014, 07:32:31 AM by Ric Gillespie »
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Tim Collins

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Re: Grand Rapids trip
« Reply #100 on: February 01, 2014, 08:52:13 AM »

...the fastener "pulling out" could account for the dimpled appearance.  ...

My point has been that I think there should be more than mere "dimpling" should be considerably more pronounced given the scenerio of rivet heads popping off that has been suggested.   
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Jon Romig

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Re: Grand Rapids trip
« Reply #101 on: February 01, 2014, 11:28:38 AM »

Jon...not sure i understand what you are saying...but the skin and rivets are not dissimilar metals; they are both aluminum...for that reason!'
They become "dissimilar" when located near a steel structure, for instance, particularly in water.
....
Bill

Hi Bill,

"Dissimilar metals" is a term that seems to be used generally to describe both dissimilar metals and dissimilar alloys, and I used it in that sense. The skin and the rivets were different alloys of aluminum.

Per Jeff Hayden's excellent and well-researched post above (#77), the rivets and the skin were dissimilar, meaning that they were well-separated on the galvanic series and thus would both experience corrosion by the same galvanic action that occurs between steel and aluminum.

Because we see no signs of galvanic corrosion on the artifact, I think we can conclude that it was not exposed to corroding condition (salt air and wetting?) for very long with the rivets in place.

It is also of interest that the one remaining rivet, shown in the NTSB report at Figure 1 (a very nice close-up photograph of the rivet) shows only minor corrosion, not what I would expect from long-duration galvanic action.

It would be very helpful to know if there is more corrosion under the head or in the rivet hole in the skin.

Jon
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« Last Edit: February 01, 2014, 11:58:50 AM by Jon Romig »
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Jon Romig

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Re: Grand Rapids trip
« Reply #102 on: February 01, 2014, 11:56:34 AM »

It occurred to me that if water from an ebbing wave acted on one side of the skin, while water from a waxing wave acted on the other side of the skin the available forces might combine, doubling the available wave force .

Yes, that is a possibility.

The most likely condition is normal atmospheric pressure of 14.7 PSI on the "other" side. I am not certain if I should be adding that 14.7 PSI to the required pressure to cause the rivets to fail - after all atmospheric pressure is providing some significant support to the skin.

In your scenario, Tim, I think that the maximum "pull" from an ebbing wave would be a pure vacuum or 0 PSI (because vacuum is always zero, never negative), thus removing the pressure of air or water on the other side. My calculation (that indicated a required pressure of 38 PSI to fail the rivets) unintentionally assumed vacuum on the "other" side.

Jon

EDIT: After more though about whether I should be adding 14.7 PSI to the failure load, I believe I should not, as both the wave and the "other" side would be under that same pressure.
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« Last Edit: February 01, 2014, 12:55:33 PM by Jon Romig »
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Ric Gillespie

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Re: Grand Rapids trip
« Reply #103 on: February 01, 2014, 01:25:11 PM »

It would be very helpful to know if there is more corrosion under the head or in the rivet hole in the skin.

There is no apparent corrosion under the head or in the hole.
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Gary L Kerr

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Re: Grand Rapids trip
« Reply #104 on: February 01, 2014, 01:46:21 PM »

If there was air and water moving around then the pressures could exceed 15 lbs.
Think of a pressure tank for a well system - anywhere pockets of air get compressed
by adding water (waves), the water and air pressure goes way up.
Gary
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