How does that work? Aeroplanes

Whether you love or hate flying, planes are always around us - or above us! It’s estimated that there are over 10,000 private and commercial planes in the skies at any one time. It’s often amazing to think that something so heavy and bulky can fly in the first place - a Boeing 747 can weigh up to 435 tons and still manage to get off the runway! So how do they get and stay up there?

Before we get to that, we need to think about some of the basic forces at work. There are four: lift, weight, thrust and drag. Lift pushes the plane up, the weight of the plane brings it down, thrust pushes it forwards and drag holds it back. Lift is probably the most important, and is mostly created by the wings.

Because of the curved nature of the upper wings, air flows faster over the top than the bottom surface as it has further to travel. Faster air has a lower static pressure, a force in the vertical direction is produced and the wing is literally sucked up by the pressure difference between the two surfaces.

Hence, once the plane has reached a good speed on the runway the wing pressure difference does the rest and the plane lifts. The flaps just increase the amount of curve on the wing, so the actual take off speed can be a little less than it would be without them. The tail steadies the plane and prevents side to side movements as it hurtles down the runway, or as it flies at altitude. Provided that the engines can produce enough thrust to overcome the drag produced by the wing, the aircraft will remain in steady and level flight. See our box below.

When the wings don’t generate enough lift, the aircraft can stall. This usually happens when the plane is flying a little too slow - so the air flowing over the wings is not enough to create the pressure difference. It can also occur when a plane’s angle of flight is very steep, for example in stunts or fighter planes, and the air behind the plane becomes turbulent and creates less lift. Luckily, most planes have onboard computer systems that don’t allow a pilot to stall in the first place.