It was a large, four-engine aircraft with the same general layout as the WD.22; a conventional floatplane with engines grouped in tractor-pusher pairs on the lower wings.

The highest priority was for a four-engine maritime patrol aircraft with an endurance of 10–12 hours, capable of maintaining altitude on two engines, in a memorandum on 26 December.

Philipp clarified on 10 February 1917 that the reconnaissance aircraft's task would be mine spotting, anti-submarine duties, and shipping control.

[1] The Naval Air Service placed an order for three improved versions of the WD.22 in 1918 to compare them with the very large floatplanes like the Zeppelin-Staaken L.[2] Designed by Karl Rösner, the WD.27 was a four-bay biplane with a wooden fuselage.

The wooden wings were hinged outboard of the engine nacelles and could be folded to the rear, which reduced the width of the aircraft to 10.5 metres (34 ft 5 in).