aviation comes of age

the dirigible
the great airships


Ferdinand von Zeppelin
Zeppelin passenger ships
Zeppelin posters
Hindenburg disaster

HMA 1 Mayfly
HMA 23
R 31
R 32
R 33
R 34
R 36
R 38
R 80
R 100
The R101 airship disaster

USS Los Angeles
the Akron
the Macon


The Great Airships

The two main technical problems faced by dirigibles were the high in flammability of hydrogen (the gas most commonly used to provide buoyancy) and the structural delicacy of a dirigible. The craft had to be light enough to float in the air, tight enough to retain the gas within its bags, and tough enough to endure winds and storms. The size of a dirigible made the drag caused by even a moderate wind significant; dirigibles crossing the Atlantic east west, against the prevailing winds, typically took twice as long to cross as they did going the other way. Yet compared to the challenges presented in creating passenger planes, these problems didn’t seem all that formidable.

The structural problems were deemed to be a matter of engineering, and the steady progress in design and alloy metallurgy offered promise that these problems would ultimately be solved. The hydrogen problem was another matter. The only apparent alternative to hydrogen was helium, which is just about eight percent heavier than hydrogen and completely inert—on the face of it, a perfect substitute.

The problem was that helium was not nearly as abundant as hydrogen, and mining and refining it was a costly process. In the 1920s the principal source for helium in the world were a handful of locations in the United States—in Texas, Utah, and Colorado—and the cost of helium at that time was ten cents a cubic foot. The typical commercial dirigible required two to three million cubic feet of the gas, which sets the cost of helium at upward of $300,000 per craft. By 1925, after considerable government effort and support, the price of helium went down to a penny a cubic foot, but that was still a thousand times more expensive than hydrogen.

From 1919 to 1937, most problems experienced by dirigibles were caused by structural breakdowns caused by weather or wind stresses. The Hindenburg explosion was the most gruesomely public and spectacular disaster involving a dirigible, but it was not typical, which was why there was so much question about how the explosion happened and why theories that the ship had been sabotaged were taken seriously. Actually, the explosion was caused by a new paint used on the airship that was highly inflammable.

At the end of the war, the Zeppelin Company was headed by Dr. Hugo Eckener, protégé of Count Zeppelin, who had died of old age in 1917. The French had captured a single Zeppelin, the L49, intact during the war and permitted British and American airmen to inspect it. At war’s end, only six Zeppelins were commandeered by the Allies before they could be destroyed by their German crews; one, the L72, the largest built to that time, was designed for the express purpose of bombing New York City.

The Germans could only gnash their teeth as they watched the Allied nations using their blueprints to build record-setting airships, and when the leading German airship pilot, Ernst Lehmann, warned that simply copying the plans without establishing a landing base experienced in the handling of these ships would lead to disaster, experts scoffed at what they regarded as a lame attempt to slow down foreign dirigible development.

The parade of airships that were built in the post-war period, only to be lost or destroyed, is remarkable. The ZR-2, built by England for the U.S. Navy, was to be housed at Lakehurst, New Jersey, in new hangars built especially for it and a companion dirigible, the ZR-1, to be built by  the United States.

Both were based on the blueprints for the German L72, the dirigible the Germans wanted to sail the Atlantic in, before being forbidden to do so by the British, who made the historic crossing in their R-34, a virtual carbon copy. During the final tests over Hull, England, the ZR-2 broke up and was destroyed, leaving the huge hangar in Lakehurst embarrassingly empty.

In Washington, a pattern began that would be repeated many times in years to come: Admiral William A. Moffet, chief of the navy’s Bureau of Aeronautics, staunchly defended the dirigible programme and vowed to  learn from the “lessons” of the ZR-2, so that the lives lost would not be in vain. (The illogic of this approach was one of the factors that eventually drove Billy Mitchell to criticize the navy.

Because the airships often seemed to meet disaster in the midst of calm flying (as the Roma, did during a carefully controlled test flight at Langley Field), the pilots were frequently unfairly blamed for the mishaps.

Richard Byrd had just missed being a passenger on the ill-fated flight, and one wonders if Moffet would have been so accepting of the loss and in such a learning mood had the celebrated explorer been among the fatalities.) A similar fate was met by the Roma, a semi-rigid dirigible built in Italy by Umberto Nobile—it was destroyed during test flights at Langley Field, Virginia, in February 1921, when it crashed into high voltage lines after being forced down by a sudden down-draft. The U.S. Army’s biggest dirigible, the C-2, exploded as soon as it left its hangar in October 1922. The L-72, renamed the Dixmude by the French, was on a flight to Africa in the winter of 1923 when it disappeared over the Mediterranean. The wreckage discovered a week later indicated that the ship had broken up in rough weather.

 Louis H. Mayfield, commander of the ZR-2 when it broke up and crashed into the Humber River, near Hull.

Thinking that there may have been something to Lehmann’s warning, the Zeppelin factories and hangars at Lake Constance and Friedrichshafen, slated to be destroyed, were spared (though Eckener had to convert them so they manufactured kitchen utensils to keen them afloat!

In 1923 a new company, the Goodyear-Zeppelin Corporation, was created to produce dirigibles, combining the newly developed alloy duralumin with German expertise and experience (much as German rocket scientists were pressed into service in the American missile and space programs after World War II). The two flagship U.S. dirigibles, the ZR-1 and the ZR-3, named the Shenandoah and the Los Angeles, were completed (in the factories in Akron, Ohio, and Friedrichshafen, respectively) and put into service in 1924. The C-2 explosion had made the navy reluctant to use hydrogen, and there was simply not enough helium for both ships, so it was decided that the two dirigibles would share the same helium and alternate flights.

The Shenandoah, which was built to military specification, toured the western states testing moorings and airfields. Then it returned to Lakehurst to transfer its helium to the Los Angeles for a more public tour promoting commercial dirigible flight. Technical problems with the Los Angeles forced it back to Lakehurst, and the navy decided to have the Shenandoah fulfil its sister ship’s engagements.

The airship’s commander, Zachary Lansdowne, complained to his superiors that the ship was not prepared for the line squalls and thunderstorms that were common in the Midwest. The ship was sent anyway, and on September 3, 1925, the Shenandoah met a storm and broke up over the Ohio countryside. Lansdowne and thirteen of the crew were killed when the control car tore loose and fell.

Several crew members sent into the hull earlier to secure one of the bags of gas, including Lieutenant Charles E. Rosendahl, clung to the bag while the rest of the craft peeled away, and landed safely twelve miles away. It was the crash of the Shenandoah that prompted Brigadier General Billy Mitchell’s intemperate remarks about the way the navy was handling its aircraft program.

The poignant photos of eastern Ohio farm folk sadly viewing the twisted wreckage of the Shenandoah stayed with many Americans and weakened popular support  for dirigible flight a dozen years before the Hindenburg disaster.

A Naval Court of Inquiry conducted a lengthy investigation, which included Lansdowne’s widow testifying about her husband’s misgivings, and Lieutenant Rosendahl, buttressed by Admiral Moffett, defending the navy’s decision. The court blamed Lansdowne for the accident and made a great many self-serving pronouncements about how the loss of the Shenandoah was the price to be paid for the lessons learned. After much debate, Congress caved in and approved the navy plan to build three replacements for the Shenandoah, two of them nearly twice its size and the other a smaller all-metal dirigible, the ZMC-2, the only dirigible that was still in active service during World War II.