O.Thetford, P.Gray German Aircraft of the First World War (Putnam)

Gotha Ursinus G.U.H. G I and U.W.D.
   This unique aeroplane, to the design of Oskar Ursinus (editor of Flugsport), was built by Gothaer Waggonfabrik A.G., in both land and seaplane versions. The landplane first flew on 27th July 1915 and the seaplane early in 1916. Several of the former version were constructed and designated G I. A crew of three was carried, and the gunner in the front cockpit had an unparalleled field of fire. The idea of raising the fuselage was to enable the engines to be placed as close together as possible - airscrew tips almost touching - in order to retain a good degree of control in asymmetric flight should failure of either engine occur. In both types "handed" airscrews were employed.
   Only a single seaplane (No. 120) was built, and was ultimately used as a school machine for torpedo crews.
   Engines, two 160 h.p. Mercedes D III. Span, 20.3 m. (66 ft. 7 1/4 in.). Length, 14.2 m. (46 ft. 7 1/8 in.). Area, 82 sq.m. (885.6 sq.ft.). Weights: Empty, 1,940 kg. (4,268 lb.). Loaded, 2,830 kg. (6,849 lb.). Speed 138 km.hr. (86.125 m.p.h.). Climb, 1,000 m. (3,280 ft.) in 8 min. (U.W.D Seaplane data.)
   Armament, two Parabellum machine-guns, both types.

J.Herris Gotha Aircraft of WWI (A Centennial Perspective on Great War Airplanes 6)

Gotha WD4 (UWD)

   The Gotha WD4, more commonly known as the UWD (for Ursinus Wasser Doppeldecker = Ursinus Water Biplane), had an interesting history. It was a floatplane derivative of the Gotha G.I bomber, which was actually designed by Oskar Ursinus, a civil engineer who was founder and editor of Flugsport magazine and not employed by Gotha. After a prototype was built, Gotha built additional aircraft as the Gotha G.I (which see).
   On 14 April 1915, only two weeks after the first order for the Gotha G.I Kampfflugzeug was received, the Navy ordered a floatplane version, the UWD, for combat evaluation. Powered by two 160 hp Mercedes D.III engines, the UWD was delivered to the SVK (Seeflugzeug Versuchs Kommando = Seaplane Testing Command) on 30 December 1915. Flight testing began on 5 January 1916 and the UWD was accepted on 6 February.
   Assigned Marine Number 120, the UWD arrived at Zeebrugge on 18 February 1916. It was easy to fly and had an endurance of at least 4.5 hours, enabling it to undertake long-range scouting and bombing missions. Nose-overs were not a problem like they were with the G.I landplane version.
   The UWD's configuration had advantages; the observer(s) had a clear view and field of fire forward, free of propeller turbulence and exhaust fumes, and the closely-spaced engines minimized asymmetric thrust in case of an engine failure. Starting 10 March 1916 the UWD made several bombing raids along the English coast until it was damaged on 10 July while taxiing for take-off. It was struck from inventory by the Navy on 2 October 1916.

Gotha WD4 / UWD Specifications
Engines: 2 x 160 hp Mercedes D.III
Wing: Span Upper 20.10 m
Span Lower 19.00 m
Chord (Upper &. Lower) 2.20 m
Gap 2.00 m
Sweepback 10 degrees
Area 82 m2
General: Length 14.20 m
Height 4.40 m
Empty Weight 1940 kg
Loaded Weight 2552 kg
Maximum Speed: 138 km/h
Climb: 1000m 8.5 min
2000m 20.5 min
3000m 45 min
Service Ceiling: 4000 m


Gotha Seaplane Production Summary
Type Ordered Marine Numbers Remarks
WD4 1 120 Ursinus design, also known as UWD