Appendix B - Propulsion primer, performance, parameters and units.



Propulsion System Comparisons


[276] The considerations of thrust and propulsive efficiency are by no means the whole story in comparing various propulsion systems. We must consider, for example, the thermodynamic efficiency of the engine cycle, or how efficiently the chemical energy of the fuel is converted to useful work such as driving the propeller and compressor, or accelerating the exhaust jet. The weight and size of the engine, its complexity, and its service life are other factors to be considered. Figure 67, from an NACA chart before....


graph of propulsive efficiency and flight velocity for propeller, turbojet and rocket

[277] Fig. 65. Propulsive efficiency peaks at different speeds for the propeller, turbojet. and rocket.


chart of peak efficiency/speed for prop planes, jets and rockets

Fig. 66. Efficiency of various propulsion systems peaks at different speeds. (Adapted from NACA figure, ca. 1953.)


chart compares flight engines on the basis
of specific weight, frontal area, and specific fuel consumption

[278] Fig. 67. Comparison of flight propulsion systems; relative values. (NACA figure. Ca 1949.)


...1950, compares flight engines on the basis of specific weight, frontal area (which affects drag), and specific fuel consumption.