Metro Jacksonville

Feel Free to add any photos you come across!

(http://liminalumen.files.wordpress.com/2007/11/dirigible1.jpg)

 :D Ya gotta love the Russians...

Now that is what I'd call BIG thinking!

Just imagine the military application for a flying carcraft carrier.

Absolutely fantastic stuff Stephendare! The Russian model is very "A typical" of most everything planned and built today. The Hindenburg, Graf Zeppelin, Akron, Macon, Los Angeles, Shenandoah, R101, Italia, etc... we're all more inside then outside the skin of the ship. Except for the control car and engineering pods where the big diesel engines we're located, everything else was up inside the body of the ship.

Jason, Imagine if the military implications if they had built the aircraft carriers? They DID! I'll post some photos, if Stephen doesn't beat me to it. (got to eat dinner first). There are photos of plane launches and recovery from a Zeppelin trapeze under the ship with a BIG airplane elevator. These are the USS Akron and Macon.

To the nay Sayer's, also consider these beauty's were killed before the experiments were finished. Moreover they died to early to see the effects of modern avionics, instrument flight, plastics and super light or strong fabrics. The reality of these new age inventions has brought the Zeppelin idea back, if you still don't believe it, check out: Boeing Aircraft, Cargo Lifter, or Zeppelin Aircraft. There is even a whole new class of Blimps (non rigid frame) dirigibles (a steerable powered ship) with FLIR and police department accessory's. Reason? The friendly helicopter can fly at 100 mph, use night vision and flood lights, chase the bad guy and hover over a crime scene for 40 minutes. A Blimp can use night vision and flood lights, chase the bad guy and hover over a crime scene for 4 WEEKS until the bad guy is starved out.  

OCKLAWAHA

Quote from: stephendare on August 19, 2009, 03:56:52 PM
(http://www.firstworldwar.com/photos/graphics/cnp_dirigible_hangar_01.jpg)
French dirigible entering its hangar on the Western Front
Is this dirty?

Do women have a love affair with zeppelins?  This picture appears to be subliminally suggestive!  :D

Stephen, just noticed your little note in the corner of the above picture.  Do "great minds" think alike?  8)

Short history of the zeppelin: 

Quote(http://www.wired.com/images/article/full/2008/03/zeppelin_500px.jpg)
Count Zeppelin's airship made its first flight over Lake Constance (or Bodensee) in southern Germany on July 2, 1900.
Courtesy Library of Congress


1899: Count Ferdinand von Zeppelin receives a U.S. patent for his rigid airship design. His name will soon become synonymous with this type of aircraft.

Zeppelin, who received a German patent nearly four years earlier, can more accurately be said to have perfected, rather than invented, the cylindrical-shaped craft. His final designs were based on ideas originally conceived by David Schwartz, a Croatian aviation pioneer employed by the German army.

Upon Schwartz's premature death, Ferdinand von Zeppelin, whose interest in maneuverable balloons went back to his days as a German military observer during the American Civil War, bought the rights to Schwartz's designs from his widow and established a commercial company.

After several false starts, including a couple of near-disastrous demonstrations, Zeppelin's rigid airship was reliable enough to attract interest from the army.

Structural rigidity, i.e., a metal airframe, is what distinguishes a zeppelin from a blimp. Zeppelin airframes were made of a lightweight alloy with a fabric skin stretched over the framework. The lifting gas that provided the buoyancy, either helium or hydrogen, was contained in multiple gas cells.

Rudders and engine-driven propellers moved zeppelins through the air, much as they propel a ship through the seas, with the fastest of them traveling at speeds of up to 90 mph.

The metal framework also allowed zeppelins to be built much larger than a gas-filled blimp. Zeppelin's prototype, LZ1, was 420 feet long. The Hindenburg, with a length of 804 feet, remains the largest aircraft ever to have flown.

Zeppelins were originally used for mail delivery and commercial aviation, which resulted in the founding of the world's first airline, DELAG, in 1909.

With the coming of World War I, the zeppelin was pressed into military service, seeing action most famously as the world's first bomber. Zeppelin raids over England were not particularly effective, but they foreshadowed the mass aerial bombardments of the next big European war.

Other nations, notably the United States and Great Britain, built zeppelins, or dirigibles, but the rigid airship is most closely associated with Germany, where, following World War I, it enjoyed a period of great commercial success as a trans-Atlantic airliner.

The spectacular explosion of the Hindenburg in 1937 spelled the end of an era, but up until then German airships had flown the Atlantic currents accident-free for a number of years.

The Nazis, too, helped kill off the zeppelin. Even before the end of World War I, fixed-wing aircraft had rendered the zeppelin useless for aerial warfare, making it irrelevant as a new conflict approached. Under direct orders from Hermann Goering, the last zeppelins had been scrapped from the war effort by 1940.

During World War II, the German navy had plans to honor Zeppelin's memory by naming an aircraft carrier for him, but, owing to the shifting fortunes of war, the Graf Zeppelin was never completed.

(Source: Various)

From: http://www.wired.com/science/discoveries/news/2008/03/dayintech_0314

Another rendering of the "whale" with an explanation:

Quote(http://www.lostateminor.com/wp-content/uploads/2008/06/zeppelin-hotel-1.jpg)

French design dynamo Jean-Marie Massaud has created a Manned Cloud. A cruise airship with a hotel for 40 passengers and 15 staff, Massaud worked with the Office National d’Etudes et de Recherche Aérospatiale in this proposal. The design is based on the way whales swim and hence has some resemblance to a very large white whale. The pure concept involves travel that is so quiet that the surrounding world does not realize that the Manned Cloud has passed by.

From: http://www.lostateminor.com/2008/06/25/zeppelin-return/

Quote(http://www.airships.net/wp-content/uploads/graf-zeppelin-lake006a-550x380.jpg)

Graf Zeppelin landing on water during polar flight

In July, 1931, Graf Zeppelin carried a team of scientists from Germany, the United States, the Soviet Union, and Sweden on an exploration of the Arctic, making meteorological observations, measuring variations in the earth’s magnetic field in the latitudes near the North Pole, and making a photographic survey of unmapped regions using a panoramic camera that automatically took several pictures per minute.  (See route of flight.)  The size, payload, and stability of the zeppelin allowed heavy scientific instruments to be carried and used with an accuracy that would not have been possible with the airplanes of the day.

The polar journey, like other zeppelin flights, was largely financed by stamp collectors; Graf Zeppelin carried approximately 50,000 letters sent by philatelists, and made a water-landing to exchange mail with the Soviet icebreaker Malygin, which itself carried a large quantity of mail sent by stamp collectors.

After the three-day Arctic flight, which included a landing in Leningrad, Graf Zeppelin returned to Berlin to a hero’s welcome at Tempelhof airfield, where the ship was met by celebrities including famed polar explorer Admiral Richard Byrd.

(http://www.airships.net/wp-content/uploads/soviet-polar-stamp.jpg)
Soviet airmail stamp showing Graf Zeppelin and icebreaker Malygin

The zeppelin visits Cairo, Egypt in 1931. Good for a sense of scale:

(http://www.kairo.diplo.de/Vertretung/kairo/de/06/Deutsche_20Spuren/zeppelin__galeriebild__4,property=BildDaten.jpg)

This one is for Ock.  A Rail Zeppelin!  Now that's a swift looking commuter train.

Quote(http://www.modellbahn.com/images/zeppelin_proto1.500x300.jpeg)

On June 21, 1931, Franz Kruckenberg's Schienenzeppelin (Rail Zeppelin) set a railway speed record that would stand for 20 years! Traveling on a track between Hamburg and Berlin, the prototype high-speed railcar sped along at 230 km per hour for approximately 20 km.

The Rail Zeppelin was never put into production, but it attracted attention wherever it went. A BMW airplane engine was used to power a four-blade wooden propeller that pushed the light-weight railcar through the air. The construction of the body was similar to the then-popular Zeppelin airships and the interior was spartan; this train was not luxurious.

The failure of the Rail Zeppelin has been attributed to everything from the dangers of using an open propeller in crowded railway stations to competition between Kruckenberg's Flugbahngesellschaft company and the Deutsche Reichsbahn's separate efforts to build a "Fliegende Zuege". The Schienenzeppelin was, however, an important part of the evolution of high speed passenger rail transport and continues to attract the attention of railroad fans and hobbyists.

From: http://www.modellbahn.com/kruckenberg.html

Quote(http://www.airships.net/wp-content/uploads/shenand-w-biplane040web-385x243.jpg)

The airship USS Shenandoah was the first American built rigid airship.  Although built in the United States, Shenandoah was based on the design of the German L-49, a World War I high altitude bomber which had been forced down intact in France in October, 1917 and carefully studied.

ZR-1 under construction
The L-49 was one of the “height climbers” designed by the Germans late in World War I, when improvements in Allied fighter aircraft and anti-aircraft artillery made it necessary for zeppelins to climb to great altitudes to avoid being shot down.  For the zepeplins to rise to greater heights on a fixed volume of lifting gas, however, the weight and strength of their structures were dramatically reduced.  This decrease in strength was accepted as a wartime necessity, since a structurally weaker zeppelin flying above the reach of enemy aircraft and artillery was safer than a stronger zeppelin that could be easily attacked.  The copying of this design for an American airship, however, may later have had tragic consequences.

Construction of ZR-1 took place during 1922 and 1923; parts were fabricated at the Naval Aircraft Factory in Philadelphia, and the ship was assembled at the Lakehurst Naval Air Station in New Jersey.  ZR-1 was 680.25 feet long, with a diameter of 79.7 feet, and could carry up to 2,115,174 cubic feet of lifting gas in 20 gas cells.  As originally built the ship carried six Packard 6-cylinder engines â€" five mounted in individual power cars attached to the hull, and one mounted at the rear of the control gondola â€" but the sixth engine was removed in 1924.

ZR-1 under construction
Like all previous zeppelins, ZR-1 had been designed on the assumption that the ship would be operated with hydrogen, but the fiery crash into the Humber River of the hydrogen inflated British R-38 (which was scheduled to become the American Navy’s ZR-2), convinced the Navy to operate the ship with helium, despite the high cost and very limited supply of the gas.

The First Flights of USS Shenandoah
ZR-1 made its first flight on September 4, 1923.  It was the first ascent of a helium inflated rigid airship in history.

ZR-1 made a series of test and demonstration flights in September and early October, 1923 â€" including an appearance at the National Air Races in St. Louis and flights over New York and Washington â€" and on October 10, 1923, the ship was christened USS Shenandoah (an American Indian term meaning “daughter of the stars”) and officially accepted as a commissioned vessel of the United States Navy.

Shenandoah’s first flights were on-the-job training for the American Navy, which had no previous experience operating a rigid airship of its own.

(http://www.airships.net/wp-content/uploads/shenandoah-patoka2-385x324.jpg)
ZR-1 Shenandoah moored to USS Patoka at sea

From: http://www.airships.net/us-navy-rigid-airships/uss-shenandoah  

Quote from: stephendare on August 19, 2009, 09:07:29 PM
Arent these babies beautiful?

Yes sir, these babies are indeed beautiful!  The white whale is incredible.  However, the super, super colossal airship port blows me away.  Can you imagine something like that existing? 

Quote from: Ocklawaha on August 19, 2009, 07:21:59 PM
Jason, Imagine if the military implications if they had built the aircraft carriers? They DID! I'll post some photos, if Stephen doesn't beat me to it. (got to eat dinner first). There are photos of plane launches and recovery from a Zeppelin trapeze under the ship with a BIG airplane elevator. These are the USS Akron and Macon.

Ock, enjoy your dinner.  Here you go, from http://www.airships.net/us-navy-rigid-airships/uss-akron-macon.  A lot more on Zeppelin history at http://www.airships.net/:

N2Y-1 training plane beneath trapeze and T-shaped opening of Akron's hangar deck:
(http://www.airships.net/wp-content/uploads/n2y-1-akron-hangar-385x298.jpg)

F9C-2 Sparrowhawk seen though hangar deck opening at bottom of hull:
(http://www.airships.net/wp-content/uploads/t-opening-216x385.jpg)

F9C-2 hooked on trapeze (left) and stowed on hangar deck (right):
(http://www.airships.net/wp-content/uploads/trazepe-hangar-deck-1024x397.jpg)

QuoteThe United States Navy airships U.S.S. Akron (ZRS-4) and U.S.S. Macon (ZRS-5) were designed for long-range scouting in support of fleet operations. Often referred to as flying aircraft carriers, each ship carried F9C-2 Curtiss Sparrowhawk biplanes which could be launched and recovered in flight, greatly extending the range over which the Akron and Macon could scout the open ocean for enemy vessels.

Development of the Akron and Macon
The Akron and Macon grew out of the Five Year Plan proposed by the U. S. Navy’s Bureau of Aeronautics, which had been approved by the United States Congress in 1926, and which authorized the construction of two large rigid airships.

The Navy contest to design and build the two new ships was won by the Goodyear-Zeppelin Corporation, a joint venture and patent sharing arrangement between the Luftschiffbau Zeppelin and the Goodyear Tire and Rubber Corporation which had been created in 1923.  (There was no serious competition for the contract, and it was clear to everyone involved in the process that Goodyear-Zeppelin was the only firm with the ability to design and construct these ships for the Navy.)  Goodyear-Zeppelin and the United States Navy signed a contract for the construction of two large rigid airships on October 16, 1928.

USS Akron:
(http://www.airships.net/wp-content/uploads/akron-072web-385x244.jpg)

USS Macon:
(http://www.airships.net/wp-content/uploads/macon-073web-385x240.jpg)

Here is another shot:

(http://bluejacket.com/usn/images/ac/p-z/zr3_losangeles__hook.jpg)
F9C Sparrowhawk approaches retractable trapeze assembly

From: http://bluejacket.com/usn_avi_lta.html

A really neat story on President Roosevelt and the USS Macon below from: http://history.sandiego.edu/gen/USPics/moffett/60th.html

Quote(http://history.sandiego.edu/gen/USPics/moffett/images/moffett17a.jpg)

....Almost immediately after arriving in Mountain View, the Macon was sent on maneuvers in the Pacific, but it was an inauspicious debut. During a mock battle, the ship was "shot down" twice in the first eight hours. In 1934, Lt. Commander Herbert Wiley, one of three survivors of the Akron crash, took command of the Macon. Determined to prove the Macon's value, he quickly developed and improved the ship's long-range detection and scouting system.

To put the system to test, the Macon left Moffett Field in July 1934 in an attempt to locate the cruiser Houston that was carrying President Roosevelt through the Panama Canal en route to Honolulu. Using only newspaper accounts of the president's departure time as a guide, the Macon raced 3,500 miles to a spot in the vast Pacific Ocean where Wiley had detennined they could find the Houston. They did. Aboard the cruiser, crewmen were shocked to see two scouting airplanes, the Sparrowhawks, come out of nowhere and circle the ship. Minutes later the Macon dramatically descended from the clouded sky and dispatched a plane that dropped bundles of the previous day's newspapers from San Francisco onto the Houston. The Fleet's admirals were not amused. Said Admiral Stanley, chief of naval operations, "We considered it a publicity stunt and that he (Wiley) had no business doing it." The president, however, was tickled. The stunt showed that the Macon was capable of the kind of scouting for which it was intended.

Unlike other dirigibles of the time, the Macon was so massive that it also carried its own protection - five Sparrowhawk fighter planes which were stored in the aircraft's belly. The airplanes were released via a trapeze and a harness which lowered the planes through a T-shaped hole in the Macon's underside. Retrieving the planes, however, was a much more difficult process. Like a performing air stunt, the pilots had to equal their speed to that of the ship and "catch" the trapeze with a hook at the top of the plane. The harness would then be attached to the fuselage, and the aircraft would be raised. Despite the difficulty of the maneuver, the pilots, known as the "Men on the Flying Trapeze" had a flawless record on both the Akron and Macon. The ship also came equipped with another scouting oddity known as a "spy" car. A cable would lower the telephone boothlike compartment from the airship to a point below cloud cover up to 1,000 feet. A crewman inside the spy car would then telephone back to the main control room relaying navigational information. The car acted as a sort of reverse telescope. The Macon and the Akron were built to be the chief scouts of the Pacific Fleet, providing long-range reconnaissance. In addition to providing protection for the "aircraft of the sky," the Sparrowhawks and the "spy" car were the ships' main eyes.

The Macon scouted for the Pacific Fleet eight times in all. But when the airship left Moffett Field on Feb. 11, 1935, to go on maneuvers off the coast of Southern California, repairs had not been completed to two tail fins that had been damaged several months earlier. Because of the need for the ship and the pressure to prove its value, Navy officials had decided to do the repair work piecemeal. Largely because of that decision, this would be the ship's 54th and final flight. The next day, as the ship was returning from its successful mission, it encountered storm winds off Point Sur, south of Monterey. Suddenly, a crosswind struck the ship with such force that the upper fins of the previously damaged tail were completely severed, sending shards of metal into the rear gas cells. In the control car, the steering wheel went slack and the navigators felt the tail drop. Wiley ordered the dumping of ballast and fuel. Crewmen hurried about the ship discharging anything they could to lighten the tail. Off-duty personnel were ordered to the nose to help bring that end down. But the ship was doomed.

After rising to nearly 5,000 feet, the Macon began to fall. Moments later the ship settled gently into the water, and the crew, clad in life jackets and prepared with life rafts - features that had not been available to many of those aboard the Akron - jumped into the water safely. Ships were quickly on the scene to pull the men out. A radioman was killed when he jumped from the failing ship, and another man was lost when he apparently tried to retrieve his belongings. But in all, 81 of the 83 aboard the Macon survived the crash, including "Lucky" Wiley. A commission set up to determine the cause of the ship's demise concluded that the blame belonged not to the crew, but to the Navy's refusal to repair the Macon's tail damage before it was sent on its ill-fated mission. The disastrous record of airships put the pressure on President Roosevelt to abandon the costly lighter-than-air program. The president responded by setting up a second commission, this one headed by Stanford Professor William F. Durand, to look into the future of airships. The panel found that dirigibles had been used for purposes for which they were not intended and that they had not been given a fair opportunity to prove their value to the military. The commission concluded that these lighter-than-air craft should be given another chance. They were not. The Macon was the nation's last rigid airship.

(http://www.aeragon.com/00/air/airship/NavyGroup-02.jpg)

Yeah, 4 weeks, though that might be a bit of a stretch on the police staked out overhead. In a worse case situation that lifting gas can keep them up there for a long, long, time. Police can stay on station at least as long as the stock of coffee and donuts holds out. One group of the new military zeppelins are unmanned and will hover on station or a year at a time.

Guess back in the great zeppelin era, there really weren't many sightings. My mother would recall how the radio kept everyone on schedule to see the Los Angeles, pass over Southwest Missouri. She said it was beyond belief that something so huge could be flying and, "It flew RIGHT OVER US!"

My dad was aiming for the lighter-then-air program in the USN, and they at least once thought he would get a spot on the USS Akron (which crashed at sea due to instrument failure). Instead the Navy put him on the Battleship USS Utah, first ship sunk in Pearl Harbour. Thankfully after several years on the Utah he had just been transferred to other duties.  

OCKLAWAHA

QuoteWe were scheduled for a flying time of 100 hours in the air. That meant we had to have plenty of everything we might need hundreds of miles out at sea. We loaded extra gasoline, oil, food, water, snacks, coffee, first aid stuff, toilet paper, blankets, tools, and electronic parts.

There you have it Stephen, 100 hours... and THAT was easy! Special thanks to "Packrat" former USN NAN-SHIP RADARMAN.

OCKLAWAHA

Airships are still being used by the U S Coast Guard


http://www.reuters.com/article/idUSN6O43930320080624

It seems like local TV news stations could use them as a much cheaper and safer alternative to the helicopter.

Cool thread !!!  Where is a picture of the ill-fated Hindenburg?

OCKLAWAHA

Quote from: Timkin on August 01, 2010, 11:09:01 PM
Cool thread !!!  Where is a picture of the ill-fated Hindenburg?

OK, we can't leave out the most famous Zeppelin picture of all, can we?

(http://www.paper-dragon.com/1939/gallery/images/1937%20-%20Hindenburg%20explosion.jpg)

(http://www.solarnavigator.net/history/explorers_history/Zeppelin_Hindenburg_disaster_burning.jpg)

Every time I saw footage of this event, it sent chills down my spine.. I cannot recall exactly what led to this disaster , but because of it, Airships were forever changed.  This was in Lakehurst, NJ right?

Quote from: Timkin on August 02, 2010, 02:17:41 AM
Every time I saw footage of this event, it sent chills down my spine.. I cannot recall exactly what led to this disaster , but because of it, Airships were forever changed.  This was in Lakehurst, NJ right?

LOL.. nice pic Ock..  I had no idea the Hindenburg actually blew up over the Courthouse ! lol

"...and this just in..."

QuoteAccording to the aerospace and defense company Northrop Grumman, the U.S. army has ordered the delivery of three Long Endurance Multi-Intelligence Vehicles (LEMV),that can carry up to 2,500 pounds payload while cruising along at 92 mph (148 kph) at the same time. Meant to be flying at 20,000 (6,096 meters) above the sea-level these super-large airships are literally longer than a football field. The army believes that the LEMVs will serve as surveillance stations and will assist in watching over battlefields in Afghanistan.

Northrop Grumman has received the $517 million dollar contract and is estimated to deliver all three LEMVs before the end of 2011

SOURCE:
http://www.livbit.com/article/tag/airship/

QuoteWill Airships Get DoD Funding Priority?

From July 20th INSIDE THE NAVY (subscription only) we learn that the US Army wants an airship.

    On July 8, Pentagon comptroller Robert Hale sent all four congressional defense committees a $3.6 billion proposal to shift funds within the fiscal year 2009 budget from lower- to high-priority needs. Within that proposal is a move to direct $5 million for the new LEMV program, which will be run -- with cooperation from the Air Force and Navy -- by the Army Space and Missile Defense Command in Huntsville, AL.

    "Funds are required to support the initial acquisition planning and development for a Long Endurance Multi-INT Hybrid Airship," states the reprogramming. "This will provide operational forces with a persistent platform of up to two weeks on-station time, with an integrated multi-INT [intelligence, surveillance and reconnaissance] sensor suite."

And a small sample of the requirements.

    A hybrid air vehicle combines the characteristics of a fixed-wing aircraft or a helicopter with a lighter-than-air technology, that uses buoyancy from gas less dense than oxygen to stay aloft.

    "Technical objectives for the LEMV include an unmanned aerial system capable of being controlled through an existing Department of Defense ground station, three-week flight endurance, 2,500 pound sensor payload, 20,000 feet operating altitude, multi-intelligence capable, 16 kilowatts of power for payload, capable of station keeping (the capability to loiter or maintain position over a required mission area in different types of weather), recoverable and reusable," states the Army's May FY-10 budget request.

    The Defense Department wants the LEMV to spend one week of its total endurance in transit and on station for two weeks, according to a Pentagon official.

A 2,500 pound sensor payload suggests a small airship, but once the services start getting involved in airships it is only a matter of time before they start looking for a larger, lift version. I don't think people fully understand how survivable airships (we are not talking about blimps here) can be.


SOURCE:
http://www.informationdissemination.net/2009/07/will-airships-get-dod-funding-priority.html

Yep you naysayers looks like a dead industry to me too! NOT!


OCKLAWAHA

Quote from: Ocklawaha on August 02, 2010, 12:28:44 AM

(http://gallery.kitmaker.net/data/16504/503px-Bundesarchiv_RM_25_Bild-30_Flugzeugtr_ger_Graf_Zeppelin_Bau.jpg)
Last two photos: The OTHER Graf Zeppelin, a Nazi Aircraft Carrier that never sailed and thankfully was pounded into razor blades at her moorings.[/center]

OCKLAWAHA

The Kriegsmarine Carrier Graf Zeppelin was actually captured by the Russian Army tied up at port after an attempted scuttle. After it was repaired, the Russian Navy towed it back apparently full of German booty.

It was bombed in 1947 by the Russian Air Force off the coast of Poland as practice and did not sink until hit with 2 torpedoes.

An oil company located it in 2007 in 87 meters of sea while doing exploration. A diving crew visited it in 2009 to view the remains.

While the RAF did attempt to bomb it at Kiel and it was reported one bomb had actually hit it, this turned out to be untrue and it was moved thereafter and sat rusting until capture.

While it could have been placed in active service in time for the war effort, it became mired in internal Nazi politics, poor Kriegsmarine performance at sea and the inability to fund the effort properly doomed it.

It was technically notable for the use of its twin rail compressed air catapults which unfortunately never made it to service.

What was the actual cause of the Hindenburg disaster, Ock?  Please don't tell me , boy-mayor shot it.. hes saving that bullet for me.. 

Quote from: Timkin on August 09, 2010, 06:12:02 AM
What was the actual cause of the Hindenburg disaster, Ock?  Please don't tell me , boy-mayor shot it.. hes saving that bullet for me.. 

In lieu of Mr Ock.

The cause was never officially determined, however many have speculated that static electricity ignited hydrogen leaking from one of modules in the rear.

Since it occurred immediately after a thunderstorm had passed, some have believed lightning struck it, but no witnesses saw it.

Conspiracy nuts think there were some hidden motives behind it (see the movie "Hindenburg") but nothing has come out of Germany or the US supporting it.

Saw the movie.. but not much of a conspiracy theory kind of guy.   Either way it was horrible.