|HA-11/33, Wn 11|
The Hopfner HA-11/33 was an amphibious flying boat built in Austria in 1933 to a specification by the Dr. Oetker company. The result was a conventional, high-wing cantilever monoplane with a stepped flying boat hull and pontoons on struts under the wings at mid-span. The cabin was fully enclosed, and the twin engines were mounted tractor-fashion on struts above the wing.
A HA-11/33 was purchased by the Austrian Air Force, and was subsequently absorbed into the German Luftwaffe following the Anschluss. Deemed worthy of further development, WNF (which had absorbed Hirtenberg, which itself had taken over Hopfner) was tasked with developing it into a military training aircraft for flying boat pilots. Designated WNF Wn 11 by the RLM, testing was undertaken at Travemünde in 1940, but the type was not ordered into production. Development of a highly streamlined derivative with Hirth HM 508 engines, the WNF Wn 11C was also abandoned.
Data from 
- Crew: 1
- Capacity: 3 pax
- Length: 10.17 m (33 ft 4 in)
- Wingspan: 14.11 m (46 ft 4 in)
- Height: 3.15 m (10 ft 4 in)
- Wing area: 30.4 m2 (327 sq ft)
- Empty weight: 1,100 kg (2,425 lb)
- Gross weight: 1,800 kg (3,968 lb)
- Powerplant: 2 × Siemens Sh 14A 7-cylinder air-cooled radial piston engines, 93 kW (125 hp) each
- Propellers: 2-bladed wooden fixed-pitch propellers
- Maximum speed: 190 km/h (118 mph; 103 kn)
- Cruise speed: 160 km/h (99 mph; 86 kn)
- Range: 900 km (559 mi; 486 nmi)
- Service ceiling: 4,500 m (14,800 ft)
- "Hopfner HA 1133 = WNF Wn 11". Retrieved 14 January 2017.
- The Illustrated Encyclopedia of Aircraft. London: Aerospace Publishing. p. 2174.
- Taylor, Michael J. H. (1989). Jane's Encyclopedia of Aviation. London: Studio Editions. p. 510.
- Nowarra, Heinz J. (1993). Die Deutsche Luftruestung 1933-1945 Vol.4 – Flugzeugtypen MIAG-Zeppelin (in German). Koblenz: Bernard & Graefe Verlag. p. 43. ISBN 3-7637-5468-7.