08/31/2011. Designed by Claude Domier at the Zeppelin-Lindau company at Lindau-Reutin, the Cs I two-seat wire-braced low-wing twin-float Jagdseeflugzeug (fighter seaplane) was to be a replacement for the much-vaunted Hansa Brandenburg W-29.
The Cs I was a radical departure from conventional structural techniques of the day and had a all-metal structure along with a stressed skin fuselage of rectangular section with large corner radii, only the flying surfaces retained the original doped linen covering. Although probably inefficient by modern standards, it was in fact a pure monocoque, as no longitudinal members were used.
The first flight was made on May 18, 1918, powered by a 170 hp Benz IIIa six-cylinder water-cooled in-line engine, that was soon superseded by an 195 hp IIIbo, optionally fitted with side coolers (as above), or with a Stirnkuhler (literally 'forehead' or front cooler). However, notwithstanding the incorporation of the highly successful structural innovations, the Cs I never made it into production. Reportedly only three were produced.