Pusher Prop............Disadvantages
I like the idea of pusher prop...............
I like the Dornier 335, Saab J21, and the above mentioned aircraft.
I especially like the Dornier 335 "push me, pull you" config............also because it could lay a big goose egg...........
Autonomously or remote UAV's seem to use this technology............
However, it stills seem this may have been a problem for attack or piloted armed aircraft ..........and here is some further ideas......
Disadvantages
The pusher configuration can endanger the aircraft's occupants in a crash or crash-landing. If the engine is placed behind the cabin, it may drive forward under its own momentum during a crash, entering the cabin and injuring the occupants; however there is no case where this has been reported to have occurred (in the US and UK accident records). Conversely, if the engine is placed in front of the cabin, it might act as a battering ram and plow through obstacles in the airplane's path, providing an additional measure of safety.
Crew members may strike the propeller while attempting to bail out of a single-engined airplane with a pusher prop. This potentially gruesome scenario helps to explain why pusher props have rarely been used on post-WWI fighters despite the theoretical increase in maneuverability.
A less dire but more practical concern is foreign object damage. The pusher configuration generally places the propeller(s) aft of the main landing gear, but often placed above the wing. Rocks, dirt or other objects on the ground kicked up by the wheels can find their way into the prop, causing damage or accelerated wear to the blades. As a result, pusher aircraft such as the carnard homebuilts are not usually operated from unimproved runways. Also, a few centreline pusher designs (such as the
Ibis canard aircraft or the
Rutan Long-EZ pictured above) place the propeller arc very close to the ground while flying nose-high during takeoff or landing, making the prop more likely to strike vegetation when the airplane operates from a turf airstrip.
When an airplane flies in
icing conditions, a layer of ice can accumulate on the wings. If an airplane with wing-mounted pusher engines experiences wing icing and subsequently flies into warmer air, the pusher props may ingest pieces of ice as they shed, posing a hazard to the propeller blades and other parts of the airframe that can be struck by chunks of ice flung by the props.
The propeller increases airflow around an
air-cooled engine in the tractor configuration, but does not provide this same benefit to an engine mounted in the pusher configuration. Some aviation engines experience cooling problems when used as pushers. Likewise, the pusher configuration can exacerbate
carburettor icing. Some air-cooled aviation engines depend on air heated by the cylinders to warm the carburettor(s) and discourage icing; the pusher configuration can reduce the flow of warm air, facilitating the formation of ice.
Propeller noise often increases because the engine exhaust flows through the props. This effect is particularly pronounced when using turboprop engines due to the large volume of exhaust they produce. Aviation enthusiasts can often hear a
Piaggio P180 Avanti approach due to the loud high-pitched wail produced by the engine exhaust blowing through the props.
Vibration can be induced by the propeller passing through the wing downwash, causing it to move asymmetrically through air of differing energies and directions.
Problems may emerge when using
wing flaps on a pusher airplane. First, the absence of prop-wash over the wings can slow the airflow across the flaps, making them less effective. Second, wing-mounted pusher engines block the installation of flaps along portions of the
trailing edges of the wings, reducing the total available flap area.
Placement of the propeller in front of the tail (as referenced in Advantages) can have a negative side effect: strong pitch and yaw changes may occur as the engine's power setting changes and the airflow over the tail correspondingly speeds up or slows down. Aggressive pilot corrections may be required to maintain the desired flight path after changing the power setting