1 Engine efficiency (25 pts) For a matched engine, the propulsive efficiency is given approximately by 2u Tsp +2u' (1) where Tsp = T/m, is the specific thrust. Using this relation,

on a single graph, plot the specific thrust and propulsive efficiency for the systems in Table 1. You may assume a thermal efficiency of 0.4. Put propulsive efficiency on the x axis (from 0 to 1) and specific thrust on the y axis (1 to 5000 m/s). Make this a semilog graph (logarithmic scale on the specific thrust axis). Represent each propulsion system as a filled area between a lower bounding curve and an upper bounding curve. For a fixed thrust, which propulsion system moves the most air mass? The least? System Propellers Turbojets Turbofans (high-bypass) Turbofans (low-bypass) Aircraft velocity (m/s) Overall efficiencies 35 - 200 240 - 600 150 - 300 150 - 600 Table 1: Systems of interest for Problem 2 30% -35% 10% - 25% 15% - 30% 20% - 30%