Single-seat ULM aircraft SD-1

piston enginesportsingle-engine

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 hour 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 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 nowadays we can see 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 as undercarriage mounts. The SD-1 main wing spar weighs only 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 the empennage 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.