The weight of an aircraft has a direct influence on its performance. The design philosophy of the SD-1 is to keep its weight as low as possible for good performance, whilst providing handling suitable for the low time pilot, but at the same time keeping it simple to build.
Historically the lightest airplanes have always been made of wood. A lot of people will have glued together a wooden model aircraft or a boat in their childhood (and many into their adulthood!) . The SD-1 is really just a bigger project, and the average builder should have no problem finishing this aircraft, particularly given the parts and kit support available for it.
The development of new materials is constantly advancing and we are now seeing Carbon composites coming into use in all sort of products. With their incredible strength and light weight these materials are very suitable for use as aircraft spar caps and in similar places with high load concentrations. Optimum properties are achieved using a manufacturing technology called pultrusion, which is a fully automated production process assuring consistent high quality and reliable mechanical properties.
For these reasons the SD-1 design uses carbon pultrusions in its spars and the reinforcement of the fuselage in such places undercarriage mounts. The SD-1 main wing spar weighs just 2 kg yet achieves an ultimate load capacity of 7.5 g thanks to this material. Overall the aircraft has a remarkable MTOW / empty weight ratio of 2:1.
The ribs of the wing and tailplane are made of extruded polystyrene. The whole aircraft is covered with plywood, with composite mouldings being used for complex shapes such as the wingtips, cowlings and fairings.
The acceptable engine power range is from 22 to 50 HP according to the requirements of the builder. Assembly and disassembly of the airframe may be performed by a single person in a short time. The design fulfils the requirements of both FAI UL and LSA regulations and also the new German ‘up to 120 kg empty weight’ category. In the UK is now the SD-1 classed as SSDR!
The SD-1 in unusual in its class being available for construction either from plans or from a range of kits of varying levels of prefabrication allowing the builder to choose an appropriate package that suits his abilities, facilities and budget.
The aim of Spacek s.r.o. is to provide the best possible support for builders of this plane and the promotion of affordable “light” aviation for everybody.