4. Propulsion
Propellers — Quiz
Test your understanding of propellers with 5 practice questions.
Practice Questions
Question 1
Why do turboprop engines require a reduction gearbox between the turbine and the propeller?
Question 2
How do swept blade tips improve propeller performance at high forward speeds?
Question 3
A propeller of diameter 2.0 m rotates at 1200 rpm. In cruise at 30 m/s, what is the advance ratio J? Show your calculation.
Question 4
If a propeller produces a thrust of 4000 N at an airspeed of 50 m/s and the engine delivers 250 kW to the propeller, what is the propulsive efficiency η? Show your calculation.
Question 5
A propeller of diameter 3.0 m has a maximum allowable tip Mach number of 0.85 at sea level (speed of sound a=340 m/s). What is the maximum safe rotational speed in rpm? Show your calculation.