Sunseeker III Becomes the Duo

Dropping a digit and its Latinate numeration, the recently renamed Sunseeker, a joint collaboration between Eric Raymond and a group of German, Swiss, Polish and Slovenian contributors, is showing progress towards its 2011 test flights.

The 23-meter (75.46 feet) span solar-powered sailplane takes its wing from the Stuttgart Akaflieg Icare II, its fuselage from the Stemme basic profiles, is being built at least partially in Poland, and uses an electric motor designed by Slovenian native Roman Susnik, as noted in an earlier entry.

Sunseeker Duo with basic specifications

The craft’s specifications provide evidence of the care employed in the design and construction of this lightweight marvel.  A 75-foot wing aircraft weighing 270 kilograms (594 pounds) empty and 470 kilograms ( 1,034 pounds) when carrying two in its side-by-side cockpit is an achievement.  Compare that to the 345 kg (765 pounds) empty weight and 550 kg (1,220 pounds) maximum weight of a “light” Piper Cub, with only a 36-foot, strut-braced wing.    The 13.8 pounds-per-foot span loading (compare to the Cub’s 33.9 pounds-per foot) of the Duo will allow reasonable climb performance on its 20 kilowatt (26.8 horsepower) motor.

Sunseeker Duo test section in Stuttgart mold. Note carbon spar caps and illustration of Solar Challenger, Aerovironment's English Channel-crossing predecessor.

Solar Flight’s web site indicates that the team has achieved a notable smoothness and integration of the wing and tail skins with the solar cells that provide power to the vehicle.  Other construction photos show similar care being exercised in laying out flying surfaces and wiring solar cells.  We wish Eric and his compatriots success in their mission to bring solar flight a step closer to commercial reality.

Eric Raymond holding extremely thin sandwich panel with solar cells neatly integrated into surface

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