David Schwarz (aviation inventor)


David Schwarz (aviation inventor)
David Schwarz

David Schwarz (Croatian: David Švarc; December 20, 1852,Note a Keszthely, Kingdom of HungaryNote b – January 13, 1897, Vienna[1]) was a Hungarian aviation pioneer of Jewish descent.[foot 1][2][3][4]

Schwarz created the first flyable rigid airship. It was also the first airship with an external hull made entirely of metal. He died before he could see it finally fly. Sources[who?] claimed that Ferdinand Graf von Zeppelin purchased the patent from his widow,[2] but Hugo Eckener disputed this.[5]

Contents

Life

David Schwarz was the son of Jewish parents.[6][7] He was a wood merchant born in Županja, but he spent most of his life in Zagreb, then part of the Kingdom of Croatia-Slavonia, Austro-Hungarian Empire.

Although Schwarz had no special technical training, he busied himself with technology and developed improvements for woodcutting machinery.[2]

Airship thoughts

Schwarz first interested himself with airships in the 1880s. This occurred as he stayed in a Croatian log cabin at the start of winter to supervise the treefelling in a newly purchased forest. As the work took longer than planned he had his wife send him literature to while away the evenings. Because the works of Charles Dickens and Victor Hugo did not appeal to him, an assumption arising from one of his wife's letters, she sent him a work from Aristotle and a Mechanics textbook. Although Schwarz became excited, it is not altogether clear this inspired him to build his own airship. The wood business suffered due to his obsession and, like other airflight pioneers, his project attracted mockery. Nevertheless his wife Melanie supported him. Schwarz busied himself using aluminium for construction, then a very new material.[2]

In Russia and the first airship

David Schwarz worked out the construction of his all-metal airship. He then offered his documents to the Austria-Hungary war minister. Great interest was shown, but no one was ready to provide financial support.[2]

The Russian military attaché, a technically educated man, advised Schwarz to demonstrate his airship in St. Petersburg.[2] There, an airship following Schwarz's idea was built in 1893.[2][8][9] Schwarz and later also his widow assumed that test flights would also be made there, but this did not happen. He began construction late 1892, with industrialist Carl Berg supplying the aluminium and necessary funding.[10] Sources report problems arose during gas-filling. George Whale wrote that on "inflation, the framework collapsed".[8] Dooley cites Robinson's detailed dimensions, weights and engine performance, and reports several deficiencies in the design: Schwarz apparently intended the metal skin to hold the gas directly without gas bags; Russian engineer Kowanko pointed out the lack of a ballonet would cause stresses on the skin during ascent and descent; the skin was not airtight; temporary "filling bags" were also not airtight, Schwarz and the manufacturer both blaming each other; and finally the skin imploded after filling directly and waiting.[11]

The specifications of this first airship were:[12]

  • gas volume: 3,280 cubic metres (116,000 cu ft)
  • empty weight: 2525 kg
  • gross lift: 958 kg
  • power: four cylinder engine weighing 298 kg, 10 horsepower (7.5 kW) at 480 rpm
  • ballast and fuel: 170 kg
  • equipment and three people: 385 kg
  • net lift: 85 kg

The circumstances of Schwarz's return is unclear, reports were of a hasty departure from Russia.[2]

Back in Germany and construction at Tempelhof

In Germany in 1894, Carl Berg procured a contract to build an airship for Royal Prussian Government, citing Schwarz as idea-provider.[13][14] Carl Berg had already experience in working and developing the then new aluminium, and was to later deliver parts for Zeppelin's first airship. With financial and technical help from Berg and his firm, the airship was designed and built.

The construction began in 1895 at the Tempelhof field in Berlin.[15] For a time the Prussian Airship Battalion put its grounds and personnel at Schwarz's disposal.[16] The pieces were produced in Carl Berg's Eveking Westphalia factory and under the direction of Schwarz, assembled in Berlin.[17] A gondola, also of aluminium, was fixed to the framework. Attached to the gondola was a 12 horsepower (8.9 kW) Daimler engine that drove aluminium propellers. One of the propellers was used to steer the craft.[8]

In 1896 June Carl Berg was in Moscow and sent a card to his stepfather, apparently indicating that he had searched for information on Schwarz and became cynical of delays and was nearly convinced he had been swindled.[18]

Due to delays, the airship was first filled with gas on 1896-10-09 and tested, but the results were not satisfactory because the hydrogen gas delivered by the Vereinigten Chemischen Fabriken from Leopoldshall (part of Staßfurt) was not of the required quality and did not provide sufficient lift. (Some sources mention a test was done on October 8, 1896.[19][20]) It was reckoned that gas with a density of 1.15 kg per cubic metre was needed. Gas with that quality could not be produced until 1897-01-13, the day of Schwarz's death.[2]

Death and maiden flight

David Schwarz' airship

Schwarz did not live to see the maiden flight of his airship. Between 1892 until 1896 he was often traveling, which had affected his health. In 1897-01-13 he collapsed in the street in Vienna by the restaurant "Zur Linde" and died minutes later in a hallway from heart failure. Historical sources[21] speak of a "Blutsturz"[2] (a term meaning either hemoptysis or hematemesis). Shortly before, he had received news that his airship was ready to be filled with gas.[2]

The city of Vienna honoured David Schwarz with an Ehrengrab (a memorial grave) and with a Grabmal (a kind of tomb) at the Zentralfriedhof.[2][22]

Carl required confirmation of Schwarz's death, suspecting he had fled to sell his secrets.[23] Nevertheless, Berg resumed the work with Melanie, Schwarz's widow and together with the Airship Battalion they completed the airship with the addition of a gas relief valve.[23]

This second airship had these specifications:[24]

  • gas volume: 4610 cubic metres
  • length 38.32 metres
  • elliptical cross-sectional area: 132 square metre, 15.4 metre wide, 18.2 metre high,
  • engine: 12 horsepower (8.9 kW) Daimler weighing 508 kg
  • vertical airscrews: three 2.6 metre diameter, two on hull, one above gondola[25]
  • horizontal airscrew: one mounted under the gondola
  • skin: 0.2 mm aluminium plates riveted to framework

Sean Dooley analysed the engineering structure from the drawings and considered it deficient such that the skin took most of the shear stresses, as could be seen in the photo in flight.[26]

The second airship tested with partial success at Tempelhof near Berlin, Germany, on 3 November 1897. Battalion mechanic Ernst Jägels[27][28] climbed into the gondola and lifted off at 15:00.[27] The ship broke free of the ground crew, and because it rose too fast Jägels disengaged the horizontal propeller.[27] At about 130 metre altitude the driving belt slipped off the left propeller, causing partial loss of steering, the ship "turned broadside to the wind, and the forward tether broke free."[27] As the ship drifted up to 510 metres the belt slipped off the right propeller, thus losing all steering.[27] Jägels then opened the newly fitted gas release valve and landed safely, but the ship turned over and collapsed.[27]

Legacy

Starting around the time of the trial flight crash, and for decades after, various reports were written, some often conflicting and misleading.

Later, Berg, and also his son would write negatively of his experiences with Schwarz.

Sources vary, some[who?] say Count Ferdinand von Zeppelin purchased the patent from his widow in 1898, others claim he used the design, however Dr Hugo Eckener addressed these claims as legend stating:

"Count Zeppelin negotiated with Herr Berg's firm for the purchase of the aluminium for his own ship. The firm, however, was under contract to supply aluminium for airships exclusively to the Schwarz undertaking. It had to obtain release from this contract by an arrangement with Schwarz' heirs before it could deliver aluminium to Count Zeppelin. That is the origin of the legend.
—Dr. Hugo Eckener[5]

Cvi Rotem (1903–1980) wrote the only known biography titled David Schwarz: Tragödie des Erfinders, Zur Geschichte des Luftschiffes, and Robinson reviewed the 187 page manuscript in the March 1984 issue of Buoyant Flight.[29] Cvi Rotem wrote that both Berg and Schwarz wished to keep their work secret.

Between 2000-12-03 and 2001-04-29 the Museen der Stadt Lüdenscheid held an exhibition which covered Berg, Schwarz and Zeppelin history from 1892 to 1932, which displayed papers, photographs and remnants.[30][31][32]

Footnotes

  1. ^ Sources do not agree as to Schwarz's nationality: some claim Austrian, others Croatian or Hungarian.

Citations

  1. ^ a b c LOC
  2. ^ a b c d e f g h i j k l German Wikipedia editors
  3. ^ Facts you didn't know
  4. ^ Jewish Science and Technology Books: Personalities
  5. ^ a b Count Zeppelin: The Man and His Work, translated by Leigh Fanell, pages 155-157, 210-211. London -- Massie Publishing Company, Ltd. -- 1938 (ASIN: B00085KPWK) (online extract)
  6. ^ "13. siječnja 1897. Umro izumitelj David Schwarz" (in Croatian). www.hrvatski-vojnik.hr (Hrvatski vojnik). http://www.hrvatski-vojnik.hr/hrvatski-vojnik/1202007/vremeplov.asp. 
  7. ^ "David Schwartz" (in Croatian). www.hakave.org (Hrvatsko kulturno vijeće). http://hakave.org/index.php?option=com_content&view=article&id=1797:david-schwartz&catid=91:znanstvenici&Itemid=119. 
  8. ^ a b c George Whale, 1995, Chapter II / Early airships and their development to the present day / Germany
  9. ^ he had started work at least by 1892-05-02 when Russian War Ministry agreed to allow him to build it there, after being rejected by the Austro-Hungarian War Ministry. Dooley, A.183 citing Robinson, p2
  10. ^ Dooley, A.184 citing Robinson, p1 and Berg, Berg and Schwarz signed a contract 1893-08-23
  11. ^ Dooley, A.185-A.186 citing Robinson, pp2-3
  12. ^ Dooley, A.185 citing Robinson, pp2-3
  13. ^ Dooley, A.186, Berg signed a contract with the Royal Prussian Government in 1894-12-16 with himself as builder and Schwarz as source of the ideas. Berg and Schwarz signed a contract on 1894-12-21
  14. ^ Dooley, A.186-A.187 Fig. 18. Battalion engineer Tenzer and Berg's engineers made drawings shown in Figure 18 titled Luftschiff David Schwarz das erste Luftschiff des starren Systems, erbaut von Commerzienrat Carl Berg.
  15. ^ Dooley, A.187
  16. ^ Dooley, A.186, in the Prussian Airship Battalion's hangar
  17. ^ Whale, Dooley, A.184. Accounts vary, George Whale wrote that the Berlin firm of Weisspfennig and Watzesch built it while Sean Dooley cites Douglas Robinson as stating these were Carl Berg's engineers.
  18. ^ Eckhard Trox et al., 2000. Objektliste.pdf exhibit list from now-stale Traum von Fliegen museum site
  19. ^ Sucur, Ante (2004). "The Airship of David Schwarz / The Construction and Testing of the Airship". http://croatian-treasure.com/airconst.html. Retrieved 19 October 2009. 
  20. ^ rr0.org quoting 'Obzor'
  21. ^ Rosenkranz, Hans (1931). Ferdinand Graf von Zeppelin: die Geschichte eines Abenteuerlichen Lebens. Ullstein. p. 58. 
  22. ^ Plot: group 63, row 36, number 13. Grabstellensuche der Stadt Wien, Simmeringer Hauptstraße 234 2. Tor 1110 Wien
  23. ^ a b Dooley A.191
  24. ^ Dooley A.191 citing Robinson page 4
  25. ^ Whale writes the central screw was for steering
  26. ^ Dooley A.192
  27. ^ a b c d e f Dooley A.193
  28. ^ Schnitzler writes Jägels was a completely inexperienced airshipman, a former Prussian Unteroffizier
  29. ^ Dooley A.183
  30. ^ Eckhard Trox 2000, Museen der Stadt Lüdenscheid German press release, and book: ISBN 978-3929614435
  31. ^ Schnitzler 2000
  32. ^ extended from 2001-03-04

References

External links


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