[1] Due to the need to be stored and launched from a submarine aircraft carrier, the W.20 was a small single-seat biplane flying boat that was designed to be assembled and dismantled quickly.

[1] It had a slender hull on which was mounted a biplane wing and a conventional braced tailplane.

[1] It was powered by a seven-cylinder, 80 PS Oberursel U.0 rotary engine — basically a German-made near-clone of the Gnome Lambda pre-war French rotary — mounted on struts between the wings driving a pusher propeller.

[1] The pilot had an open cockpit just forward of the lower wing.

[1] Because of the slender hull stabilising floats were fitted below and at the end of the lower wings.