Stealth F16's have Carbon Masts. Their tip wieght are equal to alu but could be at least 2.2kgs (5lbs) lighter. Thats why we don't carry trash bags with us? Wouter hasn't done the figures yet as he's not into anything but "raw materials". So a wing mast in carbon which can support a kite would be in my view very fast. Both upside down (sh*t happens) or the right way up.