Analysis of the specific fuel efficiency for preliminary design stage of transport category aircraft variant

The fuel efficiency index has an important place for the transport category aircraft competitiveness evaluation. The approaches for the fuel efficiency evaluation of the existing aircraft is well known and now applied for estimation calculations. But, for the preliminary design stage of the new variant creation the new approach is needed that can let control parameters selection for the required fuel efficiency level providing. There are some approaches that let it evaluate a part of weight and aerodynamic parameters of airframe and engines’ specific fuel consumption on the integral fuel efficiency index of aircraft variant for cruise flight and mean hourly fuel consumption for certification stage, when all performance of an airframe and a power plant can be fixed and their rational adjustment is not possible. New approach is proposed for the self-adjustment of a wings’ parameters and powerplant performance for the preliminary design stage. It is based on the specific fuel efficiency - specific flight productivity.