The effects of small changes to the design specification of a jet civil transport aircraft

The complexity of the equations and the number of parameters involved make it difficult to appreciate how a change to the specification of an aircraft alters the final design. The analysis in this paper gives students an insight into the interaction between the many important parameters in the design. The equations are linearised and it becomes possible to answer quantitatively questions of the form: “Aircraft_A has been designed to a given specification. Aircraft_B is to be designed with geometrically similar wings and horizontal tail and with scaled engines but with a small change to a particular specification, say the range is increased by 5%. What are the differences between aircraft_A and aircraft_B?”