Dirigible

The invention: Arigid lighter-than-air aircraft that played a major
role in World War I and in international air traffic until a disastrous
accident destroyed the industry.
The people behind the invention:
Ferdinand von Zeppelin (1838-1917), a retired German general
Theodor Kober (1865-1930), Zeppelin’s private engineer
Early Competition
When the Montgolfier brothers launched the first hot-air balloon
in 1783, engineers—especially those in France—began working on
ways to use machines to control the speed and direction of balloons.
They thought of everything: rowing through the air with silk-covered
oars; building movable wings; using a rotating fan, an airscrew, or a
propeller powered by a steam engine (1852) or an electric motor
(1882). At the end of the nineteenth century, the internal combustion
engine was invented. It promised higher speeds and more power.
Up to this point, however, the balloons were not rigid.
Arigid airship could be much larger than a balloon and could fly
farther. In 1890, a rigid airship designed by David Schwarz of
Dalmatia was tested in St. Petersburg, Russia. The test failed because
there were problems with inflating the dirigible. A second
test, in Berlin in 1897, was only slightly more successful, since the
hull leaked and the flight ended in a crash.
Schwarz’s airship was made of an entirely rigid aluminum cylinder.
Ferdinand von Zeppelin had a different idea: His design was
based on a rigid frame. Zeppelin knew about balloons from having
fought in two wars in which they were used: the American Civil
War of 1861-1865 and the Franco-Prussian War of 1870-1871. He
wrote down his first “thoughts about an airship” in his diary on
March 25, 1874, inspired by an article about flying and international
mail. Zeppelin soon lost interest in this idea of civilian uses for an
airship and concentrated instead on the idea that dirigible balloons
might become an important part of modern warfare. He asked the German government to fund his research, pointing out that France
had a better military air force than Germany did. Zeppelin’s patriotism
was what kept him trying, in spite of money problems and
technical difficulties.
In 1893, in order to get more money, Zeppelin tried to persuade
the German military and engineering experts that his invention was
practical. Even though a government committee decided that his
work was worth a small amount of funding, the army was not sure
that Zeppelin’s dirigible was worth the cost. Finally, the committee
chose Schwarz’s design. In 1896, however, Zeppelin won the support
of the powerful Union of German Engineers, which in May,
1898, gave him 800,000 marks to form a stock company called the
Association for the Promotion of Airship Flights. In 1899, Zeppelin
began building his dirigible in Manzell at Lake Constance. In July,
1900, the airship was finished and ready for its first test flight.
Several Attempts
Zeppelin, together with his engineer, Theodor Kober, had worked
on the design since May, 1892, shortly after Zeppelin’s retirement
from the army. They had finished the rough draft by 1894, and
though they made some changes later, this was the basic design of
the Zeppelin. An improved version was patented in December,
1897.
In the final prototype, called the LZ 1, the engineers tried to make
the airship as light as possible. They used a light internal combustion
engine and designed a frame made of the light metal aluminum.
The airship was 128 meters long and had a diameter of 11.7
meters when inflated. Twenty-four zinc-aluminum girders ran the
length of the ship, being drawn together at each end. Sixteen rings
held the body together. The engineers stretched an envelope of
smooth cotton over the framework to reduce wind resistance and to
protect the gas bags fromthe sun’s rays. Seventeen gas bags made of
rubberized cloth were placed inside the framework. Together they
held more than 120,000 cubic meters of hydrogen gas, which would
lift 11,090 kilograms. Two motor gondolas were attached to the
sides, each with a 16-horsepower gasoline engine, spinning four
propellers.The test flight did not go well. The two main questions—whether
the craft was strong enough and fast enough—could not be answered
because little things kept going wrong; for example, a crankshaft
broke and a rudder jammed. The first flight lasted no more
than eighteen minutes, with a maximum speed of 13.7 kilometers
per hour. During all three test flights, the airship was in the air for a
total of only two hours, going no faster than 28.2 kilometers per
hour.
Zeppelin had to drop the project for some years because he ran
out of money, and his company was dissolved. The LZ 1 was wrecked in the spring of 1901. A second airship was tested in November,
1905, and January, 1906. Both tests were unsuccessful, and
in the end the ship was destroyed during a storm.
By 1906, however, the German government was convinced of the
military usefulness of the airship, though it would not give money
to Zeppelin unless he agreed to design one that could stay in the air
for at least twenty-four hours. The third Zeppelin failed this test in
the autumn of 1907. Finally, in the summer of 1908, the LZ 4 not only
proved itself to the military but also attracted great publicity. It flew
for more than twenty-four hours and reached a speed of more than
60 kilometers per hour. Caught in a storm at the end of this flight,
the airship was forced to land and exploded, but money came from
all over Germany to build another.
Impact
Most rigid airships were designed and flown in Germany. Of the
161 that were built between 1900 and 1938, 139 were made in Germany,
and 119 were based on the Zeppelin design.
More than 80 percent of the airships were built for the military.
The Germans used more than one hundred for gathering information
and for bombing during World War I (1914-1918). Starting in
May, 1915, airships bombed Warsaw, Poland; Bucharest, Romania;
Salonika, Greece; and London, England. This was mostly a fear tactic,
since the attacks did not cause great damage, and the English antiaircraft
defense improved quickly. By 1916, the German army had
lost so many airships that it stopped using them, though the navy
continued.
Airships were first used for passenger flights in 1910. By 1914,
the Delag (German Aeronautic Stock Company) used seven passenger
airships for sightseeing trips around German cities. There were
still problems with engine power and weather forecasting, and it
was difficult to move the airships on the ground. AfterWorldWar I,
the Zeppelins that were left were given to the Allies as payment,
and the Germans were not allowed to build airships for their own
use until 1925.
In the 1920’s and 1930’s, it became cheaper to use airplanes for short flights, so airships were useful mostly for long-distance flight.
ABritish airship made the first transatlantic flight in 1919. The British
hoped to connect their empire by means of airships starting in
1924, but the 1930 crash of the R-101, in which most of the leading
English aeronauts were killed, brought that hope to an end.
The United States Navy built the Akron (1931) and the Macon
(1933) for long-range naval reconnaissance, but both airships crashed.
Only the Germans continued to use airships on a regular basis. In
1929, the world tour of the Graf Zeppelin was a success. Regular
flights between Germany and South America started in 1932, and in
1936, German airships bearing Nazi swastikas flew to Lakehurst,
New Jersey. The tragic explosion of the hydrogen-filled Hindenburg
in 1937, however, brought the era of the rigid airship to a close. The
U.S. secretary of the interior vetoed the sale of nonflammable helium,
fearing that the Nazis would use it for military purposes, and
the German government had to stop transatlantic flights for safety
reasons. In 1940, the last two remaining rigid airships were destroyed.