RE: New Sebart Wind 50E
George,
I had an Angel S 50 (6 lbs) that flew just fine on 5S. APC 15X10 and Torque Motor. I also have a 6.75 lb Osiris that flys just fine on 5S with a Hacker A50 12S on a Carbon Fiber PT Models 16X10 prop. I can fly a wide open Masters sequence with it no problem. In heavy winds it might be a bit of a struggle, but most planes that size and weight will be anyway.