The Age of The Airship

XXXIV

By the end of the decade, it was evident that the promise of "The Soaring Twenties" as the Age of The Airship had fallen far short of expectations. Most of the nations which had taken up experimenting with lighter-than-air-craft after World War I had given up on the idea, or were about to.

Graf Zeppelin (LZ-127) in Germany, 1929

France, long a leader in balloon technology, had turned its attention to airplanes even before the outbreak of The Great War. 

Britain had made a few groundbreaking strides in lighter-than-air technology, but a series of dire flying accidents ended the promise of the British program. 

Italy had done surprisingly well in airship flight technology, but had ended its dirigible experiments when it drove its homegrown designer / pilot / engineer Umberto Nobile out of the country in disgrace for political reasons. 

And the United States seemed to be particularly unlucky, wrecking four of its five functional airships between 1922 and 1935.

What was wrong with airships?  In one sense, nothing. They were vessels capable of transporting heavy cargoes great distances at low cost. They were remarkably adaptable, usable for civilian, governmental, military, exploratory, and experimental programs. They were also quiet and relatively slow flying machines that made for perfect skygoing cruise ships, and it was as cruise ships that they were introduced to the public.

In another sense, there was much wrong with airships as general purpose flying machines. They were badly misused by governments that wanted to press them into roles for which they were not designed or suitable --- like war machines or fixed-schedule transports --- "Damn the torpedoes and the thunderclouds!" --- Eventually, airlines learned to re-route, re-schedule and cancel flights in the face of seriously inclement weather.

For the most part airships were experimental craft that, built in relatively small numbers, were forced into usage as standard vehicles long before their time, and then complacently overused much as the Space Shuttles would later be. Catastrophic failures were inevitable. One could no more sail the Hindenburg into a storm front than one could sail the Titanic into an ice floe and realistically expect to avoid disaster.

The U.S.S. Shenandoah was the non plus ultra of the misused airship. The 1923 vessel was designed along the lines of a 1917 German War Zeppelin. War Zeppelins were designed to be flimsy and exceedingly light, meant to carry bomb loads at high altitudes.

Shenandoah was never meant to be a bomber. In fact, nobody was really sure what Shenandoah was meant to be. Yet the U.S. Government based her design not on the most recent commercial Zeppelins of the '20s but on an obsolete (and demonstrably flawed) design of the Nineteen-teens. Then too, Shenandoah had the less-aerodynamic sausage shape of earlier Zeppelins rather than the more-aerodynamic oblate shape of the later Zeppelins.

The fact that the U.S. used Duralumin for her frame instead of wood as the Germans had (due to wartime shortages), made no difference. Duralumin was light (which was good for lift) and was the standard framing metal for dirigibles, but it was soft, an alloy of aluminum and copper that easily deformed under stress. And since dirigibles were built with hardly any redundancies in their structures (in part to save weight, in part in design ignorance), deformation of one structural member almost always led to further structural failures. Aircraft engineering simply hadn't advanced far enough for redundancies to be built into most airship designs, especially in a "what-does-this-thing-do-anyway?' ship like Shenandoah.

Another serious problem with airships was a near-universal lack of piloting experience among airship crews. Except for the Germans, no nation had airship commanders with an adequate skill set to handle the big ships in all types of weather. The Germans had learned early --- through a series of dramatic but nonfatal accidents --- that airships were not to be launched on gusty days nor brought to mooring in storms. German airship sailors made it a point to avoid bad weather, and they were experienced in balancing and trimming their vessels in difficult air (hot weather increased lift, leading to the valving of valuable lifting gas; cold weather necessitated dumping water ballast).

All this ship trimming was complicated by the fact that most airships used hydrogen as lifting gas and that hydrogen would combust when exposed to oxygen. European airships' gas cells were made of cow intestines --- miles of them --- laboriously stitched together. There was unavoidable leakage (and loss of lift and risk of explosion) at the seams. American airships, using helium, used rubberized gasbags that did not leak, and the gas would not explode.

All in all, sailing airships took a combination of skills similar to operating an explosives-laden surface vessel, a submarine, and a multiengine airplane all at once.

With a pathetic lack of experienced crews and a crude understanding of gas physics and meteorology, it's perhaps unextraordinary that Shenandoah (and other airships) seemed to meet with disaster on a clockwork basis. 

American airship crews seemed insanely dedicated to flying their craft into challenging weather, and of the American airship fleet, Shenandoah, Akron and Macon all broke up and crashed due to gross pilot error (and it is likely that Roma did too). Shenandoah broke up as it was buffeted across the sky during a cyclone. The only American airship to survive the Soaring Twenties was the German-built U.S.S. Los Angeles (LZ-126 / ZR-3).

It was immediately after the delivery of the Los Angeles in 1924 that DELAG petitioned the Allied Control Council to build more airships. Dr. Hugo Eckener of DELAG guessed that the Allied attitude toward Germany had mellowed somewhat since 1918, and he was right. DELAG got permission to replace its fleet, and the company (which had limped along just building the Los Angeles since 1920) began to build a number of airships. It was not long before regular air service began between Germany and the Low Countries and Germany and the Baltic States, as well as intranational flights between German cities.

But DELAG's greatest airship was essentially a larger copy of the Los Angeles. Numbered LZ-127, she would be named the Graf Zeppelin.

 

U.S.S. Los Angeles (LZ-126 / ZR-3) in Panama, 1929

LZ-126 (Los Angeles) Length: 658.25 feet

LZ-127 (Graf Zeppelin) Length: 776.0 feet

LZ-126 (Los Angeles) Diameter: 90.75 feet

LZ-127 (Graf Zeppelin) Diameter: 100.00 feet

LZ-126 (Los Angeles) Volume: 2.8 million cubic feet (helium)

LZ-127 (Graf Zeppelin) Volume: 3.7 million cubic feet (hydrogen)

LZ-126 (Los Angeles) Complement: 40

LZ-127 (Graf Zeppelin) Complement: 60

LZ-126 (Los Angeles) Top Speed: 75 mph.

LZ-127 (Graf Zeppelin) Top Speed: 80 mph.

LZ-126 (Los Angeles) Flight hours: 4,398 / miles: 172,400 nm

LZ-127 (Graf Zeppelin) Flight hours: 17,177 / miles: 1.6 million nm