Trim, flaps and secondary controls

Trim

Holding pressure on the yoke for a whole flight would be exhausting. Trim lets you set the airplane to hold an attitude by itself. Most trainers have an elevator trim tab, a small hinged surface on the elevator controlled by a wheel in the cockpit. The trim tab moves opposite to the direction you want the elevator to go, and aerodynamic force holds the elevator there.

The right way to use trim: set the attitude with the yoke first, then trim away the pressure. Don't try to fly the airplane with the trim wheel. On stabilator airplanes, an anti-servo tab moves in the same direction as the trailing edge to add feel and prevent overcontrolling.

Flaps

Flaps are hinged sections on the inboard trailing edge of the wings. Extending them increases the wing's camber, which:

• Increases lift at a given airspeed, so you can fly slower.
• Increases drag, so you can descend steeper without speeding up.
• Lowers the stall speed.

That's why flaps are used for landing (a slower, steeper approach) and sometimes for short-field or soft-field takeoffs. On many trainers, extending flaps also makes the nose pitch up or down; be ready to adjust and re-trim.

The white arc

On the airspeed indicator, the white arc is the flap operating range. The bottom of the white arc is V_S0, the stall speed in the landing configuration, and the top is V_FE, the maximum flap extended speed. Extending flaps above V_FE can damage them.