Hindenburg “Explosion”

129-stitch-copyBack from Rio as Hindenburg conducted and evaluated the hook-on test flights and workers fitted out the new window cabins, the 1937 flight schedule continued with Graf leaving for Rio on April 27th and arriving there on the 1st of May. Turned around in a day, Graf departed Rio and Hindenburg lifted off from Frankfurt both on the 3rd of May. It was Graf’s 590th flight, crossing the Atlantic for the 144th time; his younger sibling was on flight number 63.  Only 36 passengers were boarded, but 61 crewmembers were aboard to attend the booked-up return flight. Just past 3,000 flight hours in his log and just passed 3,000 passengers in his register, LZ-129 left Frankfurt at 16 minutes past 8pm.  Last land checkpoint was Flushing (Vlissingen) on the Dutch island of Walcheren, where the young Herman Van Dyk watched the dirigible sail past.


41 hours into the headwind-slowed flight, a severe thunderstorm was encountered and the ship tried to climb over it, encountering the highest elevation of the trip, 1400 meters (4600 feet), logging a major valving of gas near Nova Scotia. Ice formation on all exposed surfaces accompanied the 19°F temperature drop. Passenger journalists Leonhard and Gertrud Adelt later wrote for Reader’s Digest, “On the third day we sighted Newfoundland. Binoculars and cameras appeared, and my wife’s
129-new-cabins-copydelight grew when the white dots along the coast turned out to be icebergs. The captain ordered the ship to fly low and to steer onwards them. Very slowly we passed over the most beautiful, which looked like a magic marble statue. The sun came out and laid a double rainbow around the airship. The giant iceberg turned into a monument of sparkling brilliants.” Joseph Spah took some home movies. (Note lack of ’36 Olympic rings, additional cabin windows.)


Hindenburg was too late for the 6th of May morning landing muster and wound up loitering around the New York area waiting for the evening opportunity. In SNAFU, Rosendahl wrote, “After an uneventful ocean passage that involved no weather or other factors that could in any way have severely strained or damaged her, the Hindenburg arrived at Lakehurst in perfectly normal condition, made a skillful and normal approach, and was being landed in perfectly normal way.  Three widely experienced airship captains on board had considered conditions entirely satisfactory for landing, as had we on the ground.”


g_2011-110Rosendahl does not detail his role in the American decision to perform their “high” landing technique that night;  Tyler, the new mooring officer, likely had a say as well. Whoever gave the order, it was honored by their German guests in spite of the reservations previously expressed. Cross winds throwing off the first attempted aim point, the ship was brought around again to stop and hold at about 300 feet of altitude. Line handlers were puzzled, accustomed as they were to the ship coming in over the trees and its wheel touching down, then to be grabbed and walked to the mast. Mechanic Eugen Bentelle expressed similar sentiment from those on board, “Why don’t we land?” writing in his memoir.  (63 years later Bentelle still wished the point to be made, telling the producer though a translator, “we did not land.”) Photos taken after 7 pm from the port side, in prints not heavily “dodged,” the hovering ship is but a silhouette against the clearing, brightening sky.


Per “high landing” technique, off-duty crew was ordered forward until the bow mooring line was to be safely connected to the mast’s powerful winch. Albert Grotzinger, one of the cooks, had just finished cleaning the kitchen. Grotzinger was one man without a landing station, so was tapped for the purpose. This time he was accompanied by two young helpers, Mueller and Flakus, who had enthusiastically volunteered to go forward during landing in order to see parts of the ship previously unavailable to them. Allowing them to go first, Grotzinger wound up being the last man in line. (Through a translator 63 years later, Grotzinger told the producer he wound up laying down on the walkway to watch the landing through a nearby hatch.)


Herman Van Dyk has carefully placed each individual aboard in their approximate locations as, about 7:20 pm, forward hatches were popped open. The manila yaw ropes were released to uncoil and plop onto the muddy landing field.

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In the face of volumes of speculation that the elevators were askew, wires broke, cells were slashed, valves were stuck, covering was fluttering other than in the propwash, structure was corroded, saboteurs had secreted bombs aboard, etc. etc., Rosendahl wrote, “There was no evidence that warranted any belief that there was anything wrong within the ship before the fire broke out.”


129-final-copyIndeed, there was little to do but wait until the bow yaw hawsers were secured so the mooring cable could be fed out the spindle. In this photo the stern appears to be rising slightly, as Rosendahl later mentioned it had done. Herb Morrison, the farm / music reporter sent from Chicago’s radio station WLS to interview arriving passengers, was using the first part of the record he was cutting to describe the landing. He’d mentioned rain had started to fall again, but the needle was then lifted to preserve recording time for the interviews to come. Three newsreel cameramen had left an apprentice in charge and gone off to look for hot coffee.


Unlike any previous landing, witnesses looking from the starboard side against the dark storm sky noted quite a show of nature as a phenomenally large corona hugging the insulating fabric outer cover gave a distinctive blue glow about the upper surfaces of the ship. Although too weak to be seen from port against the bright clearing sky, to be visible at all, the charge had to be enormous – quite possibly the largest in aerospace history.

This photo, also quite reworked in the print process to show details against the bright sky (it should look just like the people in the foreground),  also shows the stern’s slight rise, and the elevator man has not worked in any correction.


Meanwhile, the hemp yaw lines being hydroscopic, their absorption of the rain, and water on the ground, was rapidly reducing their natural insulating quality. The mooring cable had just begun to be winched out through the spindle when a gust came up on the bow, pulling the starboard line banjo-tight and slackening the port line. The bridge rang up power from the aft engine cars, the forward engines having been idling in reverse to guard against any possible over-riding the mast. Morrison started recording again, “The back motors of the ship.. ” when he voice  starts trailing off, “…are just holding it, uh…” indicating something is attracting his attention.


That distraction was light.  Henry W. Roberts, editor of the Aero Digest, said  “it was as bright as ‘a thousand, ten thousand, magnesium flares.’” Depending where each witness stood in relation to this Queen Mary-sized vessel hovering at 300 feet, their perception varied. Some people thought the sun had peaked out from the clouds, or fireworks were being shot off to welcome the ship’s arrival.  (Fireworks makers employ “German black” aluminum and moviemakers toss aluminum dust into igniters to simulate lightning flashes.) One passenger looking out the promenade snapped a photo of the bright light reflecting on the surface, while men under the ship noted the interior seemed to be glowing “like a Chinese lantern.” One of four crewmen in the aft, Helmut Lau, reported the light coming over his shoulder as a bright reflection on the wall of cell four, above his station.


Only one interviewed person actually saw where the light was originating from, and she knew her way around rigids.  Elizabeth Tobin, wife of Navy Chief “Bull” Tobin, himself about to make one of the most famous troop commands in aerospace history. From her position about where the old Lakehurst high mast used to be, she could blursee the stern starboard quarter. The Hindenburg’s fabric suddenly ignited as Lizzy testified, “…immediately in back of the top fin, in back of the fin, in back of the whole surface and the rudders…” The intensely bright aluminum-rich fire rapidly spread concentricly on the stern cap as an excited photographer fumbled with his camera only to get this shot, too blurry for art directors to select for publishing. (Compare the sky brightness level here with the photos above.)


As later research showed, two things had happened almost at the same time: the hydroscopic manila nose lines had had taken about 170 seconds to absorb enough moisture to become conductive. Directly connected to the ship’s frame, the tonnage of girder structure was at that moment instantly grounded. Then, the revving aft diesel engine’s exhaust, as always rich with charged electrons, was carried (by the gust they were trying to counteract) toward the stern, against the starboard side. Joining the already enormous visible corona gathered on the skin from the highly charged atmosphere, German electrical expert Professor Dieckmann later calculated the charge at the stern reached somewhere between 150,000 and 180,000 volts. Easily reaching the potential necessary to finally overcome the covering’s very high electrical resistance, the fabric became a conduction path to the grounded frame.


This was quite unlike bullets passing though fabric with miliseconds’ persistence, or even faster lightning strike passing through one end the framework and out the other. The fabric’s sudden conductivity to the corona’s flood of electrons making it a conductor ignited it, right where Lizze Tobin saw it, the area of highest potential.


Still unaware the fabric was burning aft, those under the bow and forward later described the intensifying light bouncing round the many reflective surfaces inside the ship as (per Will von Meister) “a florescent tube flickering to life.”  It’s an interesting parallel to defending British pilots’ published accounts from the Great War. Lt. W. L. Robinson had attacked the SL-11, firing his three-part ammunition upwards toward the climbing airship. Robinson described,  “A dull pink-stained glow deep inside the airship was the prelude to fiery disaster which was about to engulf Hauptmann Wilhem Schramm and the 15 members of his crew…” Similarly, landing visitor Mrs. W.R. van Meter, of Upper Darby, Pennsylvania, said  “The stern lighted up sort of like a Japanese lantern…lighted up the covering of the bag so that I could see the framework of the ship through the covering.” It’s just like the description of L31’s exit wounds catching fire opposite the defender’s position: “Even as the British airman was firing, he saw the Zeppelin ‘go red inside like an enormous Chinese Lantern…’” Unaware oxy-hydrogen fire is carbonless-clear and would not make light visible through the fabric, and having no idea they were seeing the light from the opposite side’s burning fabric, Zeppelin attackers were dismayed to see the airship continue to climb away for a time after the fabric started burning.


cubWhen fabric burns off an airplane, it’s an accident. When fabric burns off an airship, it’s not only a “disaster,” it’s always assumed something else must have been involved, with the evidence supposedly lost in the flames. This 144624_big-copy
persists in spite of any number of accounts, like Sowrey’s shooting up the L32, described as “…using drums loaded with the mixture of new Brock, Pomeroy, and tracer… first two drums apparently had no effect, but the third one caused the envelope to catch fire in several places in the center and bow.”


Eventually the Hindenburg’s fabric flame front raced around the  stern cap and also peaked over topside just forward of the vertical fin. Not just those on the starboard side aft, but most every observer could now see, as Morrison recorded, “It’s burst into flames!” With the airship still on even keel, no significant amount of lift had been lost. With a stopwatch one can count about ten seconds (knowing the recording is played back slightly faster than real time) between Morrison’s “It’s burst into flames!” and him saying “It’s falling!” By the time Morrison repeats himself, something else transpires. That controversial event in the timeline is the source of the long-touted myth that the Hindenburg’s hydrogen exploded.


In the later part of Morrison’s record, which is never played trying to make a quick buck on TV, he says he’s regained his voice: “I’ve sort of recovered from the terrific explosion…the tail surface broke into flames first, then there was a terrific explosion.”  That startling event had caused Morrison to bump into the record-cutting recorder. Assuming he had knocked the record off kilter, Morrison probably motioned to his engineer, Charles Nehlsen. One interpretation of his excited words comes out as “Get this started! Get this started!” (Others insist he says, “Get this Charlie.”) Examination of the actual record platter (returned to NARA) shows a gap, and no pressure wave of any kind is recorded thereon. Generally, the perception of loudness or concussion increased with the distance, with variables owing to relative position. An instant later AP photographer Murray Becker then took his famous image, later colorized by Dr. Addison Bain based on colorizeeyewitness accounts.

This shutter snap was at about 15-17 seconds after covering ignition.  Aft hydrogen cells I & II have just burst, one can see the ejecta blasting out of the stern, which lurched the ship forward, dislodging the water tanks seen plummeting downward. Cells III, IV & V are melting away as the ship’s structure is crushed in by the fire’s vacuum effect. Airless and with the fragile cells not representing a required robust containment, there had been no hydrogen explosion. (The fire’s random nature might seem to have allowed cells VI and VII much greater expansion than full cells I & II, since as Lau described the midship cells were “quite a bit ‘up’…” However he also said the cell above his head “disappeared because of the heat…” so they most likely were consumed before bursting.)  A form of crown fire, known as plume-dominated fire, is visible in the photo.


From that point in time, lifting gas, its containment aft no longer existent, was free to enter the rising flame plume.  Likewise with no metering apparatus to manage its mixture, the huge airless bubbles would have found little oxygen with which to mix in that firestorm. So (contrary to later TV staging, hydrogen contributed little to the overall Btu count, as the explosively flammable covering could hardly have burned with any more enthusiasm. The larger problem was the gas could not longer support the 242 ton airship at 300 feet.


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With the stern now devoid of lift, it could do nothing but plummet straight down. Unlike the ZR-1 breakup, LZ-129’s keel did not break; instead, with cell VIII and those further forward somewhat intact and full of still airless gas continuing to support their part of the ship, the keel buckled and bent. The still-buoyant mid and forward held their station until the angle became so obtuse as to cause most everyone on board to lose their footing.  This image, also rejected by art directors as out of focus, was clicked in the first instant the keel begins bending.


About one more second has elapsed when this photo was snapped; note the continued progress of the wastewater tank and the remaining tightness of the starboard yaw line. fall

 

 

 

 

 


Since one knows the acceleration of gravity the precise time could be determined; about another second has passed when this next photo shows the foamy impact of the wastewater tank splattering on the ground below, happily not striking anyone.  (Fred Bamberger, playing hooky from day classes and the night shift at Acme News Photo to ride down to Lakehurst, finally got to the single telephone about 1 am to be told he was fired. When Fred  explained he’d snapped a photo of the crash, he was rehired – and given a bonus.)

The remains of the cooked-off cells I and II and what they took skyward with them is seen raining down in Fred’s photo. The continued tightness of the starboard yaw line shows the nose has not lost one meter of altitude in spite of the complete loss of the lift from cells I-IV. Those forward lost footing as the defiantly buoyant bow fought being dragged downward, resulting in an increasingly steep angle, killing twenty-one crewmen in the process, mostly by falling.


On the accident’s 50th anniversary, Good Morning America’s Joel Siegel said “ …father of … one of the…  cameramen here told me this story. Waiting for the ship to moor, nothing seemed to be happening, so the cameramen went out for coffee, as cameramen will. They left one man watching the equipment, and that’s when the Hindenburg exploded. He turned on everybody’s camera, saved everybody’s job.”


The first exposed frames of the first camera set running barely catch the plummeting wastewater tank quickly exiting the frame  as he struggles to start all three.  Neither the newsreel cameras or released still photos capture the perfectly horizontal stern, which slams level into the ground, the four men therein stepping out with only minor injuries.


Started after the stern impact, another motion picture camera in telephoto has the midsection filling the frame, giving the impression the airship is being driven backwards into the ground. Then the seemingly impossible happens; a mid-ship cell holds, and the self-eating destruction stops.  The airship, with only the bow section still full of hydrogen and still somewhat intact, simply pitches down, as the fabric fire races forward and downward. Rosendahl would later testify “… the ship of course settled to the ground at what we would consider a moderate rate of descent…”


Another motion picture camera is lined up in time to catch the control car area at wheel touchdown, one of the most astonishing moments in the films.  At their post to the last, one of the gallant airshipman dutifully pulls a ballast toggle to hopefully slow the final landing. When the wheel finally touches the ground, the partial ship is still buoyant enough to bounce; its structure remains intact in spite of this impact, seen in this motion picture frame print.

The bow settles back down, pauses, and then the last supporting hydrogen cells pop.  This is followed by immediate and complete structural collapse, since any rigid’s gasless structure was too lightweight to be remain round without supporting “sticks” and hanging cables from the assembly hangar – let alone trying to move it without supporting gas cells.


Some terrified passengers surrounded by flames, since the bulkheads and ceiling were fabric, punched out windows and jumped, thirteen of them fatally, the only guests lost in the service’s history. Others broke limbs in their fall but survived; still others just climbed out when the floor came close to the ground.


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Art directors ignore photos of impact victims, preferring to show a crewman soaked in diesel fuel and ignited so that “nothing was left but his shoes, and they were smoking.” Ground handler Allen O. Hagaman apparently suffered a heart attack (his family said an engine car fell on him) after tripping on the mooring circle’s rail.  Captain Lehmann died of his injuries the next day.  Incredibly, most people involved in the accident survived.


Since one motion picture camera was is severely mis-framed and another is in-close telephoto,  what little footage was obtained was shared between the cameramen, before adding sound.  Paramount’s sound man, Charlie White, remembers the crew arriving with the footage for him to sound-stripe. The newsreel cameramen  were likely unaware of the record then being wished back to Chicago, and they had no agreement to use such a thing anyway, so what sound to use? Charlie White had a Vitaphone record made at the scene of a Philadelphia fire. That’s what you hear on their version of the newsreel report.


Beginning in 1994, with extensive Zep Archives research and with the help of airship enthusiasts and collectors, Dr. Addison Bain obtained original Zeppelin materials and harnessed NASA lab off-time. Bain’s study and conclusions remain the only explanation that fits the facts, and are discussed thoroughly in the producer’s book on the subject.  Dr. Bain also authored further books on the subject offering greater detail. The accident’s inferno might be summarized as follows:

The Air Force Chem Lab at Edwards AFB determined the combustion/decomposition temperature of the linen covering with its coating to be 3,347 degrees F. The ballotechnic reaction of the powdered aluminum with iron oxide would reach 5,000 degrees F. and is the likely cause of the very rapid fire spread, yet, notably, not explosive. Dr. Bain’s research showed Hindenburg’s 17 acres of cellulose butyl dsc00693-copyacetate coated fabric, which also contained wooden dowels & fairing strips, contributed about 9,000 Btus per pound. Resins, castor oils, etc. contributed over 11K Btus per pound while residual fuel oil and lubricating oils supplied 18K Btus per pound. The entire frame was coated with an alkyd/acrylic lacquer containing a phthalocynanine dye, accounting for another 11 million Btus. Of course the remaining heavy diesel fuel kept burning into the next day, in spite of efforts to extinguish it.


Not long after reporter Herb Morrison signed off his recording, interviewing survivors (he almost got Spah) and apologizing, “I hope… you don’t think it was a bad as I made it sound there at first,” Tyler was noting members of tobin-copythe ground crew who would be given special commendations.  These included Chief Bos’n Mate Fred “Bull” Tobin, whose famous shout “Navy men, stand fast!” helped keep the DELAG’s total history passenger death toll limited to those thirteen who’d jumped from the unfortunately great height. (Photo: Tobin took a commission in WWII and retired an officer.) There were investigations, boards of inquiry and reports made in the months that followed, but the Germans had it figured out in less than a year, as they retired LZ-127 and prepared to return to operations with LZ-130.


While some insist the unforgettable accident makes the future of the airship dependent not on making fireproof covering, but rather on available, affordable helium,  ZRS the movie takes no position on perfectly timed broken wires, or unnoticed stuck valves, or mad bombers, because in its universe time line, no “flying moor” was attempted after a thunderstorm. Rather, by 1942, as Buckley and Barkley correctly pointed out, all rigids would have been flying under hydrogen simply because their helium inflation and its continued support, particularly overseas, would not have been practical.


Read on to The Zeppelin Rebirth – Finding The Cause

or

Read on to Tests of the “Years of Confusion”

or

Read on to ZRCV: The Giant That Almost Was

Purchase “Hindenburg: The Wrong Paint; Hydrogen: The Right Fuel”

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