On Tuesday, July 14, 2015 at 2:48:49 AM UTC+1, Jonathan St. Cloud wrote:
What is the weight of the JS1 jet and 45 minutes of fuel over the weight of the un-engined version.

+49.7kg - of which 35.2 kg is fuel. Add to that 7 kg additional nose ballast for a 90 kg cockpit load and the wingloading still low at 38.7kg/m2 in 21m and 41.6 in 18m.