Paul Haenlein (17 October 1835 in Cologne – 27 January 1905 in Mainz) was a German engineer and flight pioneer.

It had four horizontal cylinders, which delivered about 6 horsepower (4.5 kW) with a consumption of approximately 250 cubic feet (7.1 m3) of gas per hour.

The envelope of the dirigible was rendered airtight by means of an internal rubber coating, with a thinner film on the outside.

Syngas, used for inflation, formed a suitable fuel for the engine, but limited the height to which the dirigible could ascend.

A full experiment was prevented because funds ran low, but Haenlein's work constituted a distinct advance on all that had been done previously.