Hopfner HV 1234 = HV. 12/34
Light transport aircraft Hopfner HV.12/34 (HV.1234) was developed by designer Lampihom by special order from Anton von Habsburg, prince of Lorraine. The aircraft was the first twin-engined transport aircraft built by the company Flugzeugbau Hopfner GmbH. The first flight of the prototype aircraft with tail number A-150 in the summer of 1935. In the following year , the aircraft received the registration number OE-DEA. After the annexation of Austria in 1938, the registration number was changed to D-OEEA.

The spacious fuselage was a steel tube construction, which was covered with fabric in the front and back center area with plywood at the stern. The passenger cabin space offered seats for five passengers and was luxuriously equipped. The two spar wings and tail were wooden structures, which were covered with plywood and fabric. The rudder were fabric covered. The flanding gear was fixed to the wing spars, and went through the engine cowling and had two oil dampers. Against the bottom of the fuselage, it was connected, each with a V-strut. The wheel covers were aerodynamically shaped.
The first flight took place in August 1935 at Aspern, the machine carried the registration A-150 The flight characteristics were assessed as good and the services flown in line with expectations.  The HV.12/34 flew irregularly as a private aircraft , but also as a light transport aircraft. After the annexation of Austria by Germany in 1938, the machine was still present and received the new German registration D-OEEA. Later she came to the Airborne Division of Hirtenberger Cartridge Factory AG . When war broke out, it should be used as a liaison aircraft for the Luftwaffe, but there were problems with the supply of spare parts for the engines and a conversion to German engines appeared too costly, the HV.12/34 was taken out of service. The further fate is unknown.
1 + up to 5 passengers, light transport
2 De Havilland Gipsy Major, prop.dia 2,00 m, prop. size 3,14 m2
Length 10,40 m , height 2,70 m ,  span 14,10 m , wing area 30,00 m2  , V-form 1 deg., aspect ratio 6,63
Empty 1100 kg, loaded  2000 kg, max. take off weight  2160 kg , fuel tanks 210 l
Max.. speed 205 km/h , at sea level 186 km/h cruising speed 175 km/h , range 950 km, endurance 6 h , service ceiling 4800 m, climb to 1000 m 6,25
min., to 3000 m 25 min., rate of climb 2,8 m/sec. 
First flight in August 1935. Bought by Anton Habsburg