RE Museum - Streamlining and stability

Air resistance - drag - must be kept at a minimum for economical flight. This is done by careful design and construction. All the plane's surfaces are made as smooth or as 'slippery' as possible, so there are no raised or rough surfaces to obstruct airflow. The plane is also streamlined - its cigar-like fuselage (body) is shaped to cause minimal air resistance. Designers are constantly experimenting with shapes that will decrease drag.

A plane needs a tail for stable flight just as a dart or an arrow needs a tail (or flight) to keep it travelling true. The tail has two sections - the tail fin and the tailplane. The upright tail fin corrects any tendency of the plane to yaw, or slew from side to side, as it travels through the air. The tailplane corrects the tendency of the plane to pitch or rock up and down. These two tail surfaces are often called the vertical and horizontal stabilisers.

A plane also has a tendency to roll, or rock from side to side as it flies. Rolling is reduced by inclining the wings at a dihedral angle - tilted slightly upwards so that the wings viewed from in front or behind make a V shape. This is particularly noticeable in light, low-speed planes. A plane's wings are flexible enough to flap up and down slightly in flight in response to air turbulence. This prevents them snapping under the strain.

How the pilot steers the plane

To climb, descend, or turn, the pilot manipulates control surfaces at the rear, or trailing edges, of the wings and tail. The control surfaces are hinged panels that can be moved up and down or from side to side by means of a control column (or wheel) and foot pedals.