Why do military planes have propeller blades?
Propeller driven airplanes are best for short runways, short distances and lower altitudes. Thrust is the force that results from the change in momentum of a mass of air. The momentum of the air mass is increased by a propeller or jet engine. The momentum of a mass of air is its mass times its change in velocity. A propeller moves a HUGE mass of air thru a relatively small change in velocity. This is more efficient for takeoff, climb and low altitude cruise (below 30000 ft). Jets move a relatively small mass of air thru a HUGE change in velocity. This is more efficient for high altitude cruise (above 30000 ft).
