Institute of Aircraft Design

Pfaffenwaldring 31

70569 Stuttgart


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Origin and background

For participation at the NASA/CAFE "Green Flight Challenge" the challenge aircraft e-Genius was developed. This challenge took place in  2011 near San Francisco, California USA. At a minimum range of 200 miles and a minimum speed of 100 mph the competing aircraft must not consume more than one gallon equivilant fuel per 200 miles and passenger. e-Genius is based on the fuel-cell aircraft Hydrogenius und completes the research priority "electric flying" perfectly.


Data sheet

Wing span b1: 16,9 m (55.45 ft)
Wing area S1: 14,56 m² (153.92 ft²)
Elevator span b2: 3,3 m (10.83 ft)
Elevator area S2: 1,9 m² (20.45 ft²)
Fuselage length: 8,1 m (26.57 ft)
Cockpit width: 1,10 m (3.6 ft)
Payload: 2 Persons 180 kg (397 lbs)
Engine power (shaft): 60 kW @ 2000 rpm

Performance of e-Genius with take-off weight of 850 kg

Take-off distance on grass: 285 m (935 ft)
Take-off distance over 15 m (49.2 ft) obstacle: 450 m (1,476.4 ft)
Stall speed with flaps vs0: 77 km/h (41.6 kn; 47.8 mph)
Maximum range: > 400 km (>250 mi)


From the demands of a small propulsion need results an almost inevitable configuration like a touring motor glider, because in this type of aircraft the proportion of lift to drag is particularly favorable. Furthermore the increased weight and the larger construction volume of the propulsion system must be considered compared to conventional propulsion. To minimize the increase of mass of the new propulsion system a consequent and adapted lightweight construction of the airplane structure is required. The gained experiences with icaré II in lightweight construction as well as the design for minimal propulsion need and the high efficiency of the propulsion-integration provides also a basis for Hydrogenius. The integration of the engine in the tail has proven its worth very well in the icarè II project. Particularly electrical motors with their compact and symmetrical configuration are suitable for this. The following advantages result of this situation:

  1. Compared to a conventional touring motor glider a substantial larger propeller-diameter can be realized without a high and consequentially heavier undercarriage. Therefore the propeller-efficiency will increase.
  2. The front body part has the aerodynamic quality of a modern glider (no vorticities and local impact pressure peaks) and thus a very small drag.
  3. The propeller is optimally protected from ground contact.