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Author Topic: Hindenburg on NOVA  (Read 561 times)

Ric Gillespie

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Hindenburg on NOVA
« on: May 17, 2021, 08:13:34 AM »

This from TIGHAR member and dedicated HAM Brian Harrison:

Pse spread the word

Subject: MAY 19 at 9PM on PBS NOVA

You may recognize the name of my friend and colleague from SNJ, Bob Schenck / N2OO as the editor of CQ Magazine’s monthly “DX” column, and QSL Manager extraordinaire for the most famous of DXpeditions.

A while ago he mentioned he was part of a TV documentary being made about the Hindenburg disaster and was interviewed in Hangar #1 at Lakehurst Naval Air Station in 2019. (Filming was later halted due to COVID19 but it has finally been finished.)

Bob’s mother and uncle were in Lakehurst when the Hindenburg exploded on May 6, 1937. His uncle took film footage of the explosion using his father’s Kodak 8mm movie camera. Bob kept the original film which his parents preserved all these years. Authenticated and researched, it is now finally being made public, and will prove to be an eye opener. This spectacular artifact is what’s highlighted in this new PBS NOVA documentary.
 
Wednesday May 19th on PBS NOVA, 9PM - “Hindenburg; The New Evidence.” Check your local PBS listings.
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Ric Gillespie

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Re: Hindenburg on NOVA
« Reply #1 on: May 20, 2021, 08:33:22 AM »

The NOVA show was interesting on several levels.

•   Whether there is actually any “new evidence” is arguable.  The 8mm home movie film is new to the public and it shows the event from a new angle.  The newsreel cameras were all grouped near the mooring mast and so captured the airship and fire more or less nose-on.  The amateur with the home movie camera was near the hangar and had a profile view.  The “new” view of the accident is interesting but it does nothing to resolve the question of why it happened.
•   But as we have often seen, television needs something “new” and preferably visual to build a show around - an expedition, a photo of AE and FN in Japanese custody, etc.
•   There were many echos of our own work with the 16mm Lae film.  They identified the camera by the coded markings on the film, just like Jeff did. They had the film digitized by Colorlab in Maryland, just like we did.  The scenes shot at Colorlab were very familiar.
•   Like so many TV specials, they stretched 20 minutes of material to fit a one hour show.  Great graphics, used over and over and over. Basic scientific principles dumbed-down for the television audience.
•   That said, the actual scientific aspects of the show were fascinating and convincing - testing hypotheses through experimentation.

Bottom line summary of what appears to have happened:
• Hindenburg apparently had a minor hydrogen leak in one of the aft most gasbags. The ship was noticeably tail-heavy during the final approach.  Water ballast was released and six crewmen were sent into the nose to correct the problem.
• The ship, as usual, had built up a static electricity charge on its fabric outer skin during its three day trip across the Atlantic. The charge would normally be dissipated when the ship was grounded by contacting the mooring mast.
• The fabric skin was insulated from the aluminum frame by wooden dowels to minimize the danger of a spark, and hydrogen is only flammable when mixed with oxygen.  So under normal circumstances there was no danger of fire.
•  As the ship approached the mooring mast, two mooring ropes were dropped so that the ground crew could pull the ship to the mast.  No one thought the manila ropes were conductive, but experiments showed they were.  To make matters worse, there was light rain falling.  When the ropes get wet they become much more conductive.  So, unbeknownst to anyone, the ship was grounded.  The doped fabric skin also became more conductive when it was wet.
•  The airship, in effect, became a giant capacitor and the electrical charge became sufficient to cause sparking between the skin and the aluminum frame, but there was no fire until four minutes later when the sparking, working its way aft through the 16 circumferential aluminum  girders, reached the leak and - boom.

Like most aviation accidents, the cause of the Hindenburg disaster was a combination of several separate and unrelated factors.
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Martin X. Moleski, SJ

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Re: Hindenburg on NOVA
« Reply #2 on: May 20, 2021, 01:27:39 PM »

• The ship, as usual, had built up a static electricity charge on its fabric outer skin during its three day trip across the Atlantic. The charge would normally be dissipated when the ship was grounded by contacting the mooring mast.
 ...
•  As the ship approached the mooring mast, two mooring ropes were dropped so that the ground crew could pull the ship to the mast.  No one thought the manila ropes were conductive, but experiments showed they were.  To make matters worse, there was light rain falling.  When the ropes get wet they become much more conductive.  So, unbeknownst to anyone, the ship was grounded.  The doped fabric skin also became more conductive when it was wet.


I don't understand the significance of the conductive ropes.

The first point makes it sound like grounding is a good thing, because it dissipates the charge.

The second point makes it sound like grounding is a bad thing, because it triggered discharges from the skin to the frame.

There must be a missing element here, something that made the grounding to the mast different from the grounding through the ropes.

Or would grounding to the mast have set off the accumulated hydrogen anyway?
LTM,

           Marty
           TIGHAR #2359A
 
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Harbert William Davenport

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Re: Hindenburg on NOVA
« Reply #3 on: May 20, 2021, 03:52:07 PM »

        I find Ric’s analysis and commentary very illuminating and persuasive, as usual, no surprise there.
        I do have a question, just for clarification, since for me Physics 100 was 62 years ago.  Ric wrote, “So, unbeknownst to anyone, the ship was grounded.”  He then goes on to say that the airship became, in effect, a giant capacitor, which was an important point in the explanation proposed and supported by the experimentation reported in the video.  But the key point was that in order for the ship to become a capacitor it must have two electrically separated components, one of which, the frame, became grounded by the mooring ropes, whereas the other, the skin, did not, thus creating the capacitor effect, the difference in electrical charge between the frame and the skin that built up and in a few minutes produced the sparking between the frame and the skin that ignited the leaking hydrogen.
    Isn’t the main point here NOT that the entire airship was grounded by the ropes, but rather that the ropes grounded only part of the ship, the frame to which they were attached, leaving the skin, the other electrically separate part, still ungrounded?
      The frame and the skin were the two electrically separate parts of the ship, according to the Nova program.  It would have been helpful for me to have their explanation of how the normal landing procedure, involving the mooring mast, managed to ground both the frame and the skin at the same time, or nearly so, thereby averting the hypothesized sparking that in combination with the hydrogen leak doomed the Hindenburg.
     (I wrote and posted the above before seeing Marty's post, but I think I am addressing some of his points.)
Evening addendum:  The following article has more details, provided in quotations from Prof. Konstantinos Giapis, the Cal Tech professor of chemical engineering who conducted the investigation: https://www.caltech.edu/about/news/historys-mysteries-caltech-professor-helps-solve-hindenburg-disaster
H. Wm. (Bill) Davenport
3555R Prof of Philos, ret.
 
« Last Edit: May 20, 2021, 09:54:29 PM by Harbert William Davenport »
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Martin X. Moleski, SJ

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Re: Hindenburg on NOVA
« Reply #4 on: May 21, 2021, 03:12:53 AM »

... in order for the ship to become a capacitor it must have two electrically separated components, one of which, the frame, became grounded by the mooring ropes, whereas the other, the skin, did not, thus creating the capacitor effect, the difference in electrical charge between the frame and the skin that built up and in a few minutes produced the sparking between the frame and the skin that ignited the leaking hydrogen.

Isn’t the main point here NOT that the entire airship was grounded by the ropes, but rather that the ropes grounded only part of the ship, the frame to which they were attached, leaving the skin, the other electrically separate part, still ungrounded?

That does seem to be the crucial point in this hypothesis.

Quote
      The frame and the skin were the two electrically separate parts of the ship, according to the Nova program.  It would have been helpful for me to have their explanation of how the normal landing procedure, involving the mooring mast, managed to ground both the frame and the skin at the same time, or nearly so, thereby averting the hypothesized sparking that in combination with the hydrogen leak doomed the Hindenburg.

Agreed.

Quote
     (I wrote and posted the above before seeing Marty's post, but I think I am addressing some of his points.)

You answered all of my questions, explicit and implicit.

Thanks!
LTM,

           Marty
           TIGHAR #2359A
 
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Simon Ellwood

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Re: Hindenburg on NOVA
« Reply #5 on: May 22, 2021, 06:09:56 AM »

The ropes would probably be anchored to the aluminum structure, so that structure would then be grounded, leaving a 'capacitor effect' between the skin & structure - which as described were insulated from each other.
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James Champion

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Re: Hindenburg on NOVA
« Reply #6 on: May 22, 2021, 07:59:00 AM »

If you've ever had a long-wire shortwave antenna and a neon bulb you know the effect. The antenna is suspended above ground and builds-up (or is surrounded by) charge from the air, and the neon bulb glows.  Ben Franklin did it with a key and a kite. But in this situation the air-gap is between the Hindenburg skin and the frame (like that between Ben's finger and the key). If the breakdown (arc) occurred somewhere near the top of the Hindenburg structure, then that would be where a concentration of any leaking hydrogen would also have accumulated.

Looking at Wikipedia for a quick breakdown of gases (dielectric gas entry), I see that hydrogen breakdown is 0.65 that of air. Likely that a air/hydrogen mixture also has a lower breakdown voltage. So everything else being equal, it would be more likely that the breakdown would first occur wherever there was a buildup of hydrogen near the skin.
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Martin X. Moleski, SJ

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Re: Hindenburg on NOVA
« Reply #7 on: May 22, 2021, 02:41:13 PM »

Thanks, everybody!

Your explanations are clear and, to my taste, persuasive. 
LTM,

           Marty
           TIGHAR #2359A
 
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Jeff Lange

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Re: Hindenburg on NOVA
« Reply #8 on: May 25, 2021, 05:50:20 AM »

One point that I didn't hear mentioned in the program (or I missed it) was the reason why Germany used hydrogen as opposed to helium, in their airships. The only real mention of the hydrogen was because of its' better lifting ability. However, all I have ever read on the subject was that the US had a basic monopoly on the production of helium and had an embargo of it in place against Germany. I would have thought this would have been addressed a bit more. (Again, unless I missed it.)
Jeff Lange

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Don White

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Re: Hindenburg on NOVA
« Reply #9 on: May 25, 2021, 08:13:50 AM »

Hindenburg was designed and built to use helium, but Senator Borah blocked them from getting it because of opposition to the Nazi government. Ironically, Dr Eckener was opposed to the Nazis and the Nazis only wanted an excuse to close Zeppelin down. The Hindenburg fire gave them that excuse.

LTA,
Don
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Simon Ellwood

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Re: Hindenburg on NOVA
« Reply #10 on: May 25, 2021, 08:20:54 AM »

Hydrogen is a better lifter, but only about 8-9% based on densities at STP.

The U.S. Helium Act of 1925 banned the export of helium, and at the time the U.S. was the only major source.
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Don White

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Re: Hindenburg on NOVA
« Reply #11 on: May 25, 2021, 08:41:04 AM »

Helium could be exported under a license granted by Congress, and granting that license was blocked.

LTA,
Don
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