Constraints on the selection variables reduce the feasible region of the design space. Top level requirements may specify the cruise speed or Mach number, initial cruise altitude capability and field length limitations. Explicit optimization of wing loading and thrust or power loading is carried out with the help of a design selection diagram (‘thumbprint’). The results found in the unconstrained optimization are augmented by the most relevant constraints derived from low‐speed performance requirements. Quasi‐analytical approximations are derived for the optimum take‐off lift coefficient and the minimum take‐off distance. This yields a generalized solution for the span and thrust loading constraint to comply with a specified take‐off field length. Similarly, a constraint of the landing wing loading is derived from the landing field length requirement. All constraints are introduced into the design selection chart from which the feasible region and the constrained optimizers are obtained. A figure of merit is proposed to make an initial engine selection based on the minimum weight of the mission fuel plus the power plant weight.
Matching Engines and Airframe
Advanced Aircraft Design ; 261-279
2013-06-21
19 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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