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). David Schwarz was buried in Zentralfriedhof, Vienna. Carl Berg required confirmation of Schwarz's death, suspecting he had fled to sell his secrets. 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. This second airship had these specifications: Volume: Length: 47.55 m (156 ft) Diameter: 13.49 m (44 ft 3 in) Engine: Daimler Four propellers: one of 2.6 m (8 ft 6 in) diameter between the gongal and the envelope, two of 2 m (6 ft 7 in) diameter mounted on brackets either side of the envelope, and a fourth of 2 m (6 ft 7 in) diameter revolving in the horizontal plane mounted below the gondola to drive the craft up or down. Envelope: 0.2 mm aluminium plates riveted to framework. A later structural analysis based on the drawings concluded that it was defective, with the skin taking most of the shear stresses: distortions of the skin can seen in a photo of the craft in flight. The second airship was tested with partial success at Tempelhof near Berlin, Germany, on 3 November 1897. Airship Battalion mechanic Ernst Jägels climbed into the gondola and lifted off at 3 p.m. However, the airship broke free of the ground crew, and because it rose quickly Jägels disengaged the vertical axis 'lift' propeller. At an altitude of about the drive belt slipped off the left propeller, resulting in the ship "...[turning] broadside to the wind, [and with the result that] the forward tether broke free." As the ship rose to the drive belt slipped off the right propeller, the airship thus losing all propulsion. Jägels then opened the newly fitted gas release valve and landed safely, but the ship turned over and collapsed and was damaged beyond repair. Legacy About the time of the trial flight and for decades after, various accounts, sometimes conflicting or misleading, were written of the events. Later, Berg, as well as his son, would write negatively of his experiences with Schwarz. Some sources state that Count Ferdinand von Zeppelin purchased Schwarz's patent from his widow in 1898, while others claim that the count used the design.