"Luftschiff Zeppelin 1"

XVII

Graf (Count) von Zeppelin returned from the United States in 1863 with a head full of ideas about airships. By this point in time, scientists had discovered better lifting gases than hot air. Hydrogen was cheap, available, and had the best lifting capacity. Hydrogen's chief drawback was that it was extremely combustible. Helium had about 85% of hydrogen's lifting capacity and it was not at all combustible. Helium's chief drawback was that it was rarer and hence more expensive than hydrogen. 

With no real budget, Graf von Zeppelin began designing and building a hydrogen airship (in German "Luftschiff") in association with a metallurgist, Carl Berg. Up until meeting the Graf, Berg had been working with a little-known aircraft designer, David Schwarz. Realizing that the Graf's military rank and title would take him further, Berg broke off his affiliation with Schwarz, taking Schwarz's airship plans with him. Schwarz sued Berg and Graf von Zeppelin, but unsurprisingly, the courts held for the landed aristocrat. Some years later, Graf von Zeppelin paid 15,000 marks to Schwarz's Estate for his ideas. 

Still, nobody listened to Graf von Zeppelin, not until the French launched an airship (they called it a "dirigible" or "steerable") in 1884, and named it La France. 

 

To be honest, it wasn't much of an airship design. It consisted of a gasbag full of hydrogen (called an envelope) that also contained small balloons (balonettes) full of regular air. Altitude and attitude were controlled by the balonettes. When they were deflated the ship would rise (hydrogen being lighter than air) and when inflated the ship would lower (air being heavier than hydrogen). Power was provided by a kerosene-powered propeller that pulled (rather than pushed) La France through the air. La France had a top speed of six miles per hour. But it did fly (a round trip of five miles), and it did return to its point of origin safely. The German government became alarmed. They decided they needed airships to counter this threat from the sky.

Von Zeppelin's (or actually, Schwarz's) design was far superior, and was based on seagoing ship design. A seagoing vessel consists of a keel at the very bottom from which are built up parallel vertical ribs (frames) across which are laid horizontal beams and strakes in a V, U, or half-circle shape. Machinery, decks, and accommodations are placed within this cagelike structure. This construction is then plated over forming a heavy, solid hull which is (hopefully) impervious to water.

The liner SS Kungsholm under construction

  

In a Zeppelin Luftschiff, the cage is made into a complete cylinder. Gasbags (called cells) full of hydrogen (or helium) are placed within the cage, which is then covered with fabric forming a light, soft hull. Machinery, decks, and accommodations are placed within gondolas which are suspended from the underside of the hull. In some later and larger airships like the Hindenburg, machinery, decks and accommodations were also placed within the keel structure and inside the hull.

Graf von Zeppelin flew his first airship in 1900. Designated LZ-1 (Luftschiff Zeppelin 1) it was a long, sausagelike affair. A lot of gas had to be used to provide adequate lift, and so the hulls of airships tended to be gargantuan, especially in comparison to their payloads. LZ-1 was 420 feet long and thirty eight feet in diameter. It held 400,000 cubic feet of hydrogen and had a rated lift of 27,400 pounds. It was powered by two Daimler diesel engines and could sail at 15 knots. 

Airships always "sailed". Properly speaking, they never "flew".