Gotha WD.10 Ursinus Seaplane

O.Thetford, P.Gray German Aircraft of the First World War (Putnam)
J.Herris German Seaplane Fighters of WWI (A Centennial Perspective on Great War Airplanes 2)
J.Herris Gotha Aircraft of WWI (A Centennial Perspective on Great War Airplanes 6)

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

Ursinus Seaplane
Another most interesting design of Ursinus was his seaplane fighter of 1916, with retractable floats designed to lie flat against the lower part of the fuselage when cranked up by the pilot. It was an attempt to overcome the inherent disadvantages of drag and manoeuvrability which attended float planes generally and fighters in particular. To improve manoeuvrability the engine was located on the centre of gravity and the airscrew driven through an extension shaft. The general cleanliness of the aeroplane, for the 1916 period, was remarkable. Unfortunately the prototype was destroyed during trials, and the estimated top speed of 200 km.hr. (124 m.p.h.) had not been achieved by that time. Engine, 150 h.p. Benz Bz III. Span, 9.00 m. (29 ft. 6 3/8 in.). Length, 7.77m. (25ft. 6 1/2 in.). Height, 2.9 m. (9 ft. 6 1/4 in.) floats down; 2.0 m. (6 ft. 6 3/4 in.) floats retracted. Weights: Empty, 749.5 kg. (1,649 lb.). Loaded, 1,002 kg. (2,205 lb.).

J.Herris German Seaplane Fighters of WWI (A Centennial Perspective on Great War Airplanes 2)

Ursinus Floatplane Fighter

The most innovative single-seat floatplane fighter prototype built was the Ursinus, which had retractable floats for higher speed through reduced drag. To improve maneuverability the engine was located on the center of gravity and drove the propeller via an extension shaft. The floats were retracted by a manual crank. During trials there were problems with the propeller extension shaft and float retraction mechanism. The prototype was destroyed before it could achieve its estimated top speed of 200 km/h. Its Marine Number was 782.

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

Gotha WD10 (U-1)

Like the Gotha WD4/UWD, the Gotha WD10, Marine Number 782, was another design by Oskar Ursinus, a civil engineer who was founder and editor of Flugsport magazine.
The WD10, more commonly known as the U-1 or Ursinus Seaplane after its designer, was the most innovative single-seat floatplane fighter prototype built in Germany and a remarkable design for 1916. It featured retractable floats for higher speed through reduced drag. To improve maneuverability the 150 hp Benz Bz.III engine was located on the center of gravity and drove the propeller via an extension shaft. The floats were retracted by a manual crank. During trials there were problems with the propeller extension shaft and float retraction mechanism. Unfortunately, the prototype was destroyed before it could achieve its estimated top speed of 200 km/h.

Gotha WD10 (U-1) Specifications
Engine: 150 hp Benz Bz.III
Wing: Span Upper 9.00 m
Area 42.5 m2
General: Length 7.77 m
Height 2.90 m
Empty Weight 750 kg
Loaded Weight 1000 kg
Maximum Speed: 200 km/h

Gotha Seaplane Production Summary
Type Ordered Marine Numbers Remarks
WD10 1 782 Ursinus design, retractable float fighter

Самолеты (сортировка по:)
Страна	Конструктор	Название	Год	Фото	Текст

	J.Herris - Gotha Aircraft of WWI /Centennial Perspective/ (6)
	Oskar Ursinus (Editor of Flugsport magazine) designed a single-seater to embrace several features intended to obtain the very best performance from the 150hp Benz six-cylinder engine. Built by Flugmaschinen Rex GmbH and allocated naval number 782, the aircraft is shown at Warnemunde during evaluation in April 1917. The most revolutionary feature of the design was its retractable float undercarriage. The pilot manually operated a small differential winch which reduced the lengths of the bracing cables on one diagonal of the undercarriage struts and lengthened corresponding cables on the other diagonal, allowing the floats to be cranked to the 'up' position. They were retracted forward against the airflow; this kept the centre of gravity forward and also assisted with float extension. In the event, the aircraft was never flown, since during initial taxiing trials at 900rpm the machine nosed over. After further investigation the design was abandoned.
	J.Herris - Gotha Aircraft of WWI /Centennial Perspective/ (6)
	The Ursinus floatplane fighter, Marine Number 782, seen from the side with floats extended.The cockpit was well aft because the engine was set back to the center of gravity for improved maneuverability (due to reduced moment of inertia) and drove the propeller via an extension shaft.
	J.Herris - German Seaplane Fighters of WWI /Centennial Perspective/ (2)
	The Ursinus floatplane fighter Marine Number 782 seen from the side with floats extended. The cockpit was well aft because the engine was set back to the center of gravity and drove the propeller via an extension shaft.
	J.Herris - Gotha Aircraft of WWI /Centennial Perspective/ (6)
	The Ursinus floatplane fighter was unique in having retractable floats, a significant innovation for its time. The inside upper edges of the floats were beveled to fit closely against the fuselage, which was shaped to accommodate them when retracted.
	J.Herris - Gotha Aircraft of WWI /Centennial Perspective/ (6)
	The Ursinus was an innovative design attempt to reduce the drag penalty of floats combined with an attempt to improve maneuverability through reducing the moment of inertia by locating the engine at the center of gravity.
	J.Herris - Gotha Aircraft of WWI /Centennial Perspective/ (6)
	About the same time as the Junkers J.I was making its debut, the Gotha WD-10 was nearing completion, ready to enter flight trials early in 1916. While not representing such a fundamental advance as the J.I, this Oskar Ursinus creation merits more than passing interest for the novel and clever fashion in which the designer minimised the deleterious effects such things as floats would otherwise have on the fighter's overall performance. Thanks to its refined in-flight lines, brought about by the retractable floats, the WD-10, with its 150hp Benz Bz III had a top level speed of 124mph at sea level. At this speed, the German single seat naval fighter could outpace France's finest, in the shape of the Spad VII, first flown in April 1916. Perhaps it was fortunate for the Allies that the WD-10 was destroyed during flight test. The images not only show the aerodynamically cleansing affect of the retractable floats, but also the extremely neat housing of engine and fuselage flanking radiators devised by the Ursinus design team.