Exam Question

### Introduction to Propulsive Efficiency
Propulsive efficiency (η_p) is the measure of how effectively the power delivered to the propeller (Delivered Power, P_D) is converted into useful thrust power (Thrust Power, P_T). A significant portion of the energy delivered to the propeller is lost in the form of rotational and axial kinetic energy imparted to the slipstream, as well as frictional losses. The devices described below aim to recover a portion of this lost energy or modify the flow to the propeller to increase the overall efficiency.
$$ \eta_{p} = \frac{P_{T}}{P_{D}} = \frac{T \times V_{a}}{2 \pi n Q} $$
Where: