A derivative of the Hopfner HS-5/28 via the Hopfner HS-8/29, the HS.9 was a parasol wing monoplane with a fixed tailskid landing gear and room for two occupants in tandem open cockpits, and first flew as the Hopfner HS-9/32 in 1932, powered by a de Havilland Gipsy I engine. Production versions had Siemens Sh 14 engines with NACA cowlings. A single example of a refined version with an uncowled Siemens engine was flown in 1935 as the Hopfner HS-9/35, shortly before the Hopfner company went bankrupt.

When Hopfner's assets were purchased by Otto Eberhardt Patronenfabrik, production continued of both de Havilland- and Siemens-powered aircraft under the Hirtenberg brand.

• HS-9/32 - Original version by Hopfner
• HS-9/35 - developed version of HS-9/32
• HS.9 - Production aircraft with a Siemens Sh 14a piston engine.
  • HS.9A - Production aircraft with a de Havilland Gipsy Major piston engine.
• HS.16 - military trainer version of HS.9

  Austria

• Austrian Air Force (1927-1938)

Data from British Civil Aircraft since 1919 Volume 3.^[1]

General characteristics

• Crew: 2
• Length: 8.05 m (26 ft 5 in)
• Wingspan: 10.972 m (36 ft 0 in)
• Empty weight: 568.8 kg (1,254 lb)
• Gross weight: 948 kg (2,090 lb)
• Powerplant: 1 × de Havilland Gipsy Major , 90 kW (120 hp)

Performance

• Maximum speed: 190 km/h (118 mph, 103 kn)

• The Illustrated Encyclopaedia of Aircraft. London: Orbis Publications. 1982–1985. p. 2173.