Figure 3-22: Trend in overall efficiency of propulsion
h (solid circles), computed from aircraft specific fuel consumption (SFC)
data (open circles; data as in Figure 7-9), according to h = V(Q SFC)-1, with
V as the aircraft speed (~240 m s-1 ) and Q as the specific heat of combustion
of aviation fuels (43 MJ kg-1). Solid circles also denote the critical altitude
z (right axis) above which contrails form (for 100% relative humidity in the
mid-latitude standard atmosphere) for the years 1960 to 2010. SFC data were
taken from a figure Subsonic Engine-Specific Fuel Consumption at Cruise Versus
Certification Date originating from a NASA report and presented by H.G. Aylesworth
at the Working Group Meeting CAEP-4, WG3 Emissions, International Civil Aviation
Organization, 20-23 May 1997, Savannah, GA, USA.
