David Schwarz was a Croatian-Hungarian aviation pioneer of Jewish descent born in the Austrian Empire. He is known for creating the first airship with a rigid hull, in his case one made entirely of metal, an essential step in creating a dirigible, that is: an airship whose flight trajectory can be fully controlled with the help of engine-driven propellers.
Background
David Schwarz was born in Keszthely, Kingdom of Hungary, then part of the Austrian Empire, the son of Jewish parents. He was a timber merchant raised in Županja, but he spent most of his life in Agram, formerly also part of the Austrian Empire, then part of the Austro-Hungarian Empire and today's Zagreb, capital of Croatia.
Education
Although Schwarz had no special technical training, he became interested in technology and developed improvements for woodcutting machinery.
Career
Having worked out the design of an all-metal airship, Schwarz then offered his ideas to the Austro-Hungarian war minister. Some interest was shown, but the government was not ready to provide financial support.
The Russian military attaché, a technically educated man, advised Schwarz to demonstrate his airship in St. Petersburg, where an airship using Schwarz's ideas was built in 1893. Schwarz, and later his widow, assumed that test flights would also be made there, but this did not happen. He began construction in late 1892, with the industrialist Carl Berg supplying the aluminium and necessary funding.
Problems arose during gas-filling: on inflation, the framework collapsed. Schwarz apparently intended the metal skin to contain the gas directly without internal gas bags. The Russian engineer Kowanko pointed out that the lack of a ballonet would cause stresses on the skin during ascent and descent.
In 1894, the German industrialist Carl Berg procured a contract to build an airship for the Royal Prussian government, referring to Schwarz as the originator of the idea. Berg already had experience working with the then novel aluminium, and was to later manufacture components for Zeppelin's first airship. With financial and technical help from Berg and his firm, the airship was designed and built.
Construction began in 1895 at the Tempelhof field in Berlin. For a time the Prussian Airship Battalion placed its grounds and personnel at Schwarz's disposal. The components were produced in Carl Berg's Eveking Westphalia factory and, under the direction of Schwarz, assembled in Berlin. A gondola, also of aluminium, was fixed to the framework. Attached to the gondola was a 12 hp (8.9 kW) Daimler engine that drove aluminium propellers. One of the propellers was used to steer the craft.
In June 1896 Carl Berg sent a card to his stepfather from Moscow apparently indicating that he had searched for information on Schwarz and became cynical of delays and was nearly convinced he had been swindled.
Due to delays, the airship was first filled with gas and tested on 9 October 1896, but the results were not satisfactory because the hydrogen gas delivered by the Vereinigte Chemische Fabriken from Leopoldshall (part of Staßfurt) was not of the required purity and did not provide sufficient lift. However, some sources mention that a test was performed on 8 October 1896. It was determined that gas with a density of 1.15 kg per cubic metre was needed. Gas of that quality could not be obtained for some time, and the test flight could not be made until November 1897, roughly ten months after Schwarz's death in January of that year.
Schwarz did not live to see his airship fly. Between 1892 and 1896 he traveled frequently, which affected his health. Shortly before his death he received news that his airship was ready to be filled with gas. On 13 January 1897 he collapsed outside the "Zur Linde" restaurant in Vienna, and died minutes later from heart failure, aged 44. Historical sources speak of a blutsturz (a term meaning either hemoptysis or hematemesis).
Interests
He became interested in technology and developed improvements for woodcutting machinery.