**4. Insights regarding integrated hybrid-electric transport aircraft**

By reviewing concepts out of the cloud illustrated in Figure 3, insights regarding the integrated prospects of hybrid-electric transport aircraft are presented in this section. The development of algebraic parameters and figure-of-merits to enable the assessment of aircraft utilizing electric drive for the propulsion system are introduced first. The integration implications of the hybrid-electric propulsion system on aircraft overall sizing and performance are then detailed based on three investigated hybrid-electric narrow-body transport aircraft concepts.
