Fuselage                                                                                                      Fuselage is of wood truss design with prevalent section 15x15 mm covered with plywood of 0,8-3 mm thickness. The pilot seat back is inclined under 40°. This assures comfort also for 185 cm (6,1 ft) tall pilot. The height of cabine is possible to modify for taller pilot if necessary. The inside with of cockpit in shoulder place is 54 cm (21,3"). The plywood tunel with wing and upper gear legs mounts is under pilot knees. The baggage compartment of 40 l (0,15 ft³) is behind removable seatback. Composite cabin hood with polycarbonate windshield of 2 mm thickness opens to the side. It is lockable. The NACA inlet for ventilation is on the side of cabine hood.

Wing                                                                                                                                     Two part wing uses GA 37U-A315 airfoil. It consists of composite main spar with carbon caps on which are glued ribs made of extruded polystyren. It is covered with 1 mm plywood. Wingtips are made of extruded polystyren with fiberglass layup or premolded are vacuum bagged sandwich. The weight of painted wing half is 12 kg (27 lbs). Connection of wings to fuselage is made thru two main and two auxiliary pins.  Disassembly of wings takes 5 and assembly 10 minutes. The connection of flaperons to controls is performed by simple inserting of control pin into slot. 

Tail                                                                                                                                      The all movable horizontal tail (HT) has anti-servo tab and is statically balanced. Tails are of similar construction as wings- on composite spar are attached polystyrene ribs and plywood skin. Spring trimming is under pilot seat. Disassembly of HT is made thru disconnection of control and tab rods and pulling out of pin. The fin has main composite spar with carbon caps and HT hinge.

Undercarriage                                                                                                                   The legs of main gears are made of pultruded fiberglass rods. The wheels of 12x4 size are braked using mechanical drum brakes. Tail wheel of 100 mm (4") diameter is controlled via ruder and is attached to the fiberglass spring.

Controls                                                                                                                                       The horizontal tail and flaperons are controlled via pushrods and bellcranks. Rudder is controlled via ropes.

Engine                                                                                                                                            The prototype of airplane is driven by Trabant auto conversion with 120x70 (48"x27.5") propeller fitted directly on the crankshaft. The Trabant engine is good choice for SD-1 due to its robustness, high reliability, low consumption and cost.

Serial airplanes are till now driven by Hirth F-33 AS, F-23 AS and B&S Vanguard 22 HP engines. It is possible to use any engine of 22-50 HP power range up to 40 kg (89 lbs) weight. This criterion fulfil e.g. Hirth 2702, Simonini Victor 1, 2SI 460 F, 1/2 VW etc.

Fuel system                                                                                                                           The integral tank of 28 l (7.4 US gal.) capacity is placed behind fuselage firewall. It is made of fiberglass-PVC foam sandwich. The Mikuni pump is connected to crankcase. The auxiliary electric pump is placed on the firewall. 

Electrical system                                                                                                                 The bus is juiced by battery and is charged by alternator integrated in electronic ignition. It is possible to place 12 V outlet under instrument panel for GPS etc.

Instruments                                                                                                                                     The airplane is fitted with basic flying instruments-speedometer, altimeter, compass and vario. The RPM´s, total hours, head and exhaust gas temperatures are checked on the engine. There is place for COM transceiver with installing diameter of 57 mm in the instrument panel. The COM antenna is built in the airframe. The transponder could be placed to the socket on the cockpit floor.

Rescue system                                                                                                                 The prototype airplane is equipped with rescue system GRS 4/270. The container of system is attached on fuselage bulkhead behind pilot´s back. The front ropes are attached on upper engine mount hinges. The auxiliary rope is attached to fuselage behind cabin.                                                                                                  It is possible to use also other systems in serial version. If is used light engine is possible to mount rescue system on the firewall. It is possible to built airplane without rescue system.

Specifications    

Performance  

*valid for plane equiped with Hirth F-33 AS (28 HP) engine, without rescue system    ** Hirth F-33 AS engine                                                                                  ***Hirth F-33 AS engine and propeller 120x95 (48x37.4)