Volmer Jensen VJ-21

 

Some disadvantages of tractor type installations:

-The propeller accelerates air rearward which strikes the surface of the airplane resulting in what is called “scrubbing drag.”

-For small single-engine aircraft greater than 50% of the aircraft surface behind the propeller experiences this type of drag.

Some advantages of pusher type installations:

-Enhanced wing efficiency because the airflow over the wing is not disturbed by the propeller.

-Superior visibility out the front of the aircraft. The cockpit is placed well forward of the wing for weight and balance purposes resulting in improved visibility.

-Improved slow speed control as the prop blast is closer to the tail surfaces.

-A pusher needs less stabilizing vertical tail area and therefore presents less weathervane effect. The aircraft would generally be less sensitive to crosswind on takeoff.

Some disadvantages for pusher type installations:

-Power-plant cooling design is more complex than for tractor configurations where the propeller forces air over the engine.

-Due to the center of gravity often being further back on the longitudinal axis than on most tractor airplanes, pushers can be more prone to flat spins, especially if loaded improperly.

-The propeller passes through the fuselage wake, wing and other flight surface down-washes reducing propeller efficiency (some 2 to 5% less than tractor types).

-Pusher props are noisy, especially if the engine exhaust flows through the prop.

-There is a possibility of the engine momentum causing the engine to enter the aircraft cabin during a crash.

-Pusher props will tend to pick up material that is thrown into the air by the main landing gear.

-Pushers tend to have longer instrumentation and control runs back through the cabin to reach the engine.

-There is a possibility of the engine momentum causing the engine to enter the aircraft cabin during a crash.

-Pusher props will tend to pick up material that is thrown into the air by the main landing gear.

-Pushers tend to have longer instrumentation and control runs back through the cabin to reach the engine.