Section B chapter 3 Stability

Stability is when a airplane in flight can return to being steady after it has been disturbed. If a airplane has been disturbed it tends to go back to its original position. This is called positive static stability; when it doesn't go back but keeps jumping around its called positive dynamic stability. Maneuverability is how well the plane handles and withstands stress. Controllability is how good a airplane responds to your control input.

There are three axes of flights. This is how a plane will rotate. The common reference point is called the center of gravity evn though it is imaginary. Longitudinal axes is when you begin a turn and you roll around the longitudinal axis. You will continue on the longitudinal as long as the ailerons are engaged. Lateral axis is when a plane pitches and leans side to side. Vertical axis is yawing which is the rear of the plane swings lift to right.

The longitudinal stability of an airplane means how much pitching motion a plane has. Longitudinally unstable planes are dangerous to fly. When a plane is designed they have to think about balance. The pressure of the wings in relationship to the center of gravity is important. The pressure of the wings has to be forward to the center of gravity. The center of gravity is decided by how the weight of the airplane is distributed. If the CG is too forward the plane becomes nose heavy. When baggage is loaded into a airplane it has to be spread around to maintain the center of gravity.

When a Plane is properly loaded the CG is in front of the center of pressure and the airplane is a little nose heavy. The nose heaviness is off set by the horizontal stabilizer, which provides a downward force.

Lateral stability is keeping the plane from rolling. A design called dihedral is the upward angle of the airplanes wings, it's only a few degrees. Another design feature is called sweepback, where the wing is positioned at an angle instead of straight 90 degrees.

Why is stability important? One reason is so we don't have stalls. Stalls will be something we practice during our flying practice. Pilots learn when a stall is coming and how to correct it. Poor stability also leads to spins like a cork screw. pin recovery will also be something I learn in the air.