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The SD-1 Minisport Design Philosophy
The weight of an airplane has a direct influence on its performance. The design Philosophy of the SD-1 is as light as possible while simple to built airplane, good performance and handling suitable also for low time pilot. Historically the lightest airplanes have always been made of wood. Every boy has tried to glue together a wooden plane or boat. The SD-1 is really just a bigger model, so the average builder should have no problem finishing the plane. The development of new materials continues non-stop. We are now seeing items in daily use made of carbon composites, with its incredible strength and light weight. Its strength/weight ratio deserves its use in places with high load concentration like spar caps and similar. Top properties are achieved using pultrusion technology. This fully automated process assures constant quality of production and mechanical properties. This is the reason why we use it in spars and reinforcement of fuselage. The main spar of wing weights 2 kg (ultimate load 7,5 g).The MTOM/empty weight ratio achieves value 2,1. The design is maximaly simple. The ribs of wing and tails are made of extruded polystyrene. Whole plane is covered with plywood and composites are used on the complex shapes only. The engine power range is from 23 to 50 HP what should fulfil requirements of every pilot. Assembly and disassembly of plane is possible to perform by one person in a short time. The plane fulfils requirements of both FAI UL and LSA regulations and also new German up to 120 kg category. The aim of our company is the best possible support for builders of this plane and promotion of “small” aviation for everybody.
The fuselage is of wood truss design with prevalent section 15×15 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 in standard version. The height of cabine is possible to modify for taller pilot if necessary (up to 2 m pilot in XL version- see following folder). The inside width of cockpit in shoulder place is 54 cm (21,3″). The plywood tunel with wing and upper gear legs mounts (TD) is under pilot knees. The baggage compartment of 40 l (1,5 ft3) is behind removable seat back. Additional baggage compartment could be made behind pilot bulkhead when is rescue system not used. The composite cabin hood with polycarbonate windshield of 1,5 mm thickness opens to the right side and could be performed as lockable. The NACA inlet for ventilation is on the right side of cabine hood.
Two half 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.
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.
Could be performed in TD, TG or TGC version. See description in following folders
The horizontal tail and flaperons are controlled via pushrods and bellcranks. The flaperon mixer is under seat. The rudder is controlled via cables of 2 mm diameter.
It is possible to use any engine of 24-50 HP power range up to 42 kg (93 lbs) weight. See available Engine kits.
The integral tank of 34 l capacity is placed behind firewall. It is made of fiberglass-PVC foam sandwich.
The bus is juiced by battery and is charged by alternator on all offered engine kits. It is possible to place 12 V outlet under instrument panel for GPS etc.
The airplane is usually fitted with basic flying instruments-airspeed indicator, altimeter, compass, vario and slip indicator. The EFIS-es up to Dynon SV-D700 size could be used. There is enough space for any engine gauges combination. There is place for COM transceiver and TPD with installing diameter of 57 mm in the instrument panel. The COM antenna is built in the airframe.
It is possible to built airplane also less rescue system.
The airplane could be equipped with rescue system GRS 4/240, Magnum 300 or similar weight range. The container of rescue system is attached to fuselage bulkhead behind pilot´s back. The front ropes are attached to upper engine mount hinges. The auxiliary rope is attached to fuselage behind cabin. In the case of light engine use (B&S, Hirth F-33) is rescue system mounted on the firewall.