(GB2328657-A)      The solar cells generate energy for at least one electric motor driven propeller (31-34). The cells are located on at least one additional surface (21,22,25,26) outside of the aircraft wings (10,11) with the additional surface alignable according to the solar radiation direction.    The alignment is carried out by the additional surfaces swivelling about an axis (23,24,27,28), extending parallel and/or orthogonally to the aircraft longitudinal axis (35). Additional surfaces maybe aligned about a second axis during the flight by the slipstream.    USE -   For light observation aircraft, operating above 10,000m.    ADVANTAGE -   High energy yield with low air flow resistance.    (DE19716650-C2)      The solar cells generate energy for at least one electric motor driven propeller (31-34). The cells are located on at least one additional surface (21,22,25,26) outside of the aircraft wings (10,11) with the additional surface alignable according to the solar radiation direction.    The alignment is carried out by the additional surfaces swivelling about an axis (23,24,27,28), extending parallel and/or orthogonally to the aircraft longitudinal axis (35). Additional surfaces maybe aligned about a second axis during the flight by the slipstream.    USE -   For light observation aircraft, operating above 10,000m.    ADVANTAGE -   High energy yield with low air flow resistance.    (GB2328657-B)      The solar cells generate energy for at least one electric motor driven propeller (31-34). The cells are located on at least one additional surface (21,22,25,26) outside of the aircraft wings (10,11) with the additional surface alignable according to the solar radiation direction.    The alignment is carried out by the additional surfaces swivelling about an axis (23,24,27,28), extending parallel and/or orthogonally to the aircraft longitudinal axis (35). Additional surfaces maybe aligned about a second axis during the flight by the slipstream.    USE -   For light observation aircraft, operating above 10,000m.    ADVANTAGE -   High energy yield with low air flow resistance.