Great topic. For reference, the self-launching sailplane uses about 3 litres for a three thousand foot launch, including taxiing. I'm amazed that all the upper surfaces of the Antares aren't photovoltaic. Wouldn't do much for the current (sorry) launch, but during the flight could recharge the batteries. Most of the solar charge controllers we use on small systems are old technology. The latest MPPT (maximum power point tracking) stuff seems quite efficient. Used three different vintages of controller at home (a 1500W system) and noticed the difference at each upgrade. A friend is all excited about something he calls "nukular" batteries. Don't crash... http://www.sciencedaily.com/releases/2009/10/091007124723.htm There are a few battery technology links on that page. Jim
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