What is the ratio of flight speed to the exhaust velocity for maximum propulsion efficiency ?
What is the ratio of flight speed to the exhaust velocity for maximum propulsion efficiency ?
Propulsive efficiency for a jet engine is given as
\[\eta _{p}=\frac{2}{1+\frac{v_{e}}{U}}\]
Therefore from above we can see that maximum propulsive efficiency is obtained when flight speed should be equal to the exhaust velocity,the ratio should be equal to 1.