 SSDRs (Single Seat De-Regulated) aircraft had to weigh less than without fuel and pilot, and the wing loading could not be more than 10 kg/m2

However, the UK CAA changed the rules in May 2014, and the new SSDR rules state that the aircraft must be single seat, and must have an MTOW of 300 kg, i.e.it must weigh no more than 300 kg at takeoff, including pilot and fuel.Also, the stall speed must be 35 knots or less.