SPaircraft is a signomial programming compatible transonic aircraft conceptual design optimization tool. It is of similar level of fidelity as TASOPT, and can perform the single- and multi-mission optimization of a variety of aircraft configurations. The fuselage, wing, horizontal tail, vertical tail, and landing gear models are documented in the AIAA Journal of Aircraft paper "Application of Signomial Programming to Aircraft Design" which can be found at here and here. The engine model is contained in the separate convexengineering/turbofan repository and documented in the AIAA Journal of Aircraft paper "Turbofan Engine Sizing and Tradeoff Analysis via Signomial Programming" which can be found here and here.