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Airplane
Systems
Propulsion System
Airplanes use two major types of
propulsion
systems:
propellers and jet engines. A propeller is driven by an internal
combustion engine, and jet engines draw air into the engine where it is
compressed and mixed with
jet fuel. This air/fuel mixture is ignited under high
pressure, and the expanding hot gasses are forced out the back of the
jet engine.
Control and
Guidance Systems
Airplanes have moveable surfaces such
as a
rudder, ailerons, elevators, and flaps. Slight movement of these
surfaces creates drag, allowing pilots to steer and slow down the plane
when needed.
Pilots are able to navigate accurately by using charts, global
positioning, and visual aids to navigation. In addition, large
aircraft are aided by on-board computers and a complex, world-wide air
traffic control system.
Structural System
An airplane has three main structural
components. The fuselage is the large center section that
contains the pilot, passenger, and cargo compartments. The wings
help to provide lift and often contain the fuel tanks. The tail
section includes the rudder, elevators, and the vertical stabilizer.
The structural system as a whole is called the airframe.
Suspension System
In flight, airplanes are suspended in
Earth's atmosphere and must overcome the force of gravity.
Engineers use their knowledge of physics to design aircraft that will
capitalize on the physical properties of the atmosphere and the
predictable effects of gravity.
The forces of flight are thrust, lift, drag, and weight.
• Thrust is the forward motion provided by the propulsion
system.
• Lift occurs as a result of the shape of the wings and the
behavior of the airflow around them. Airplane wings are curved on
top and generally flat on the bottom. As the airplane moves
through the air, the air flows faster on the top of the wing than on
the bottom. The faster air creates a lower pressure area on top
of the wing, and the higher pressure below the wing creates a lifting
force.
Also contributing to lift is the angle of attack, or the upward slope
of the wings. It is the angle at which the wing is situated
relative to the ground.
• Drag is the force of fluid friction on moving objects.
The friction causes resistance and slowing of an air vehicle.
• Weight is the pull of gravity, and must be overcome by lift.
Aerodynamic System
Aircraft are designed with smooth,
rounded
shapes to reduce drag. Polished surfaces and/or smooth paint will
further reduce the effects of fluid friction.
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