The SD-260 featured a strut-braced biplane layout, a two-seats-in-tandem open cockpit, with an optional bubble canopy, fixed conventional landing gear with wheel pants and a single engine in tractor configuration.
The aircraft fuselage was made from welded 4130 steel tubing. Its 22.00 ft (6.7 m) span had a wooden structure with four ailerons, a wing area of 135.0 sq ft (12.54 m2) and was covered in doped aircraft fabric. The wing was supported by interplane struts, cabane struts and flying wires. The acceptable power range was 200 to 400 hp (149 to 298 kW) and the standard engine used was the 260 hp (194 kW) Lycoming IO-540 power plant.
The SD-260 had a typical empty weight of 1,250 lb (570 kg) and a gross weight of 1,850 lb (840 kg), giving a useful load of 600 lb (270 kg). With full fuel of 29 U.S. gallons (110 L; 24 imp gal) the payload for the pilot, passenger and baggage was 426 lb (193 kg).
The standard day, sea level, no wind, take off with a 260 hp (194 kW) engine was 600 ft (183 m) and the landing roll was 800 ft (244 m).
The manufacturer estimated the construction time from the supplied kit as 1200 hours.