We are already flying for more than a 100 years. The first motorised airplane was built by the American brothers Wright. In 1903 they completed their first controlled flight with their self made airplane that they called 'The Flyer'.
An airplane weighs thousands of kilos. Some airplanes can weigh up to 400.000 kilos! For a lot of people it is thus a miracle that such a big machine is able to stay airborne. But actually it is quite logical. The fact that an airplane can stay in the air has to do with aerodynamics and propulsion.
An airplane, just like any other object, is being pulled down by gravity. To prevent that an airplane will fall down during flying, an airplane creates something called lift, that 'lifts' gravity. In the horizontal direction an airplane faces air resistance. To go in a forward direction there are propellors or engines that move the airplane forward.
When an object moves through the air, then this is called aerodynamics. You will also find this term used often when someone is talking about sailing and windmills. When you look carefully at a wing of an airplane, then you will find that the top is much rounder than the bottom. Imagine following two air particles, of which one goes along the top and the other round the bottom. Along the top of the wing, the air particle needs to travel a lot further. The speed of the air at the top is thus much faster than at the bottm.
Through the law of Bernoulli this story becomes even clearer. Maybe you have learned about this theory at school. This law tells you that when a gas, such as air, flows quicker, the pressure becomes less. This is thus what happens with a wing of an airplane. The pressure on the top of the wing is much lower than that at the bottom, which makes it possible that the airplane stays airborne.
Now it has probably already become a little bit more clear how it is possible that an airplane can fly. Actually the airplane is 'hanging' in the air, because the pressure at the top of the wings is lower than at the bottom. There is however the condition that the wings really move, otherwise there can not be a difference in pressure. This means that there also needs to be a flow of air. To start a flow of air, we of course need engines. These will ensure that the wings gain enough speed with regards to the surrounding air. In this way a balance can be created, in which there are two forces on the horizontal plane to be observed. This is the resistance of the airplane and the forward propelling power of the engines. Vertically there are also two forces that are visible. These are the lift, that is going upwards and the weight.
Now you don't have to be scared that the airplane stops straight away when the engines stop working. Besides, that the engines stop during a flight, luckily only happens very rarely. But when the engines stop, then the airplane can still travel for quite a long distance by simply gliding. Pilots take back the power of the engines when they are starting the descend. As a passenger you can hear this slowing down of the engines. The engines are not turned off, but they are going stationary. They are then hardly supplying any propulsion, because this is not necessary anymore. This is comparable to an engine that has been switched off or broken down. When the descend of the airplane has started it usually takes about 20 minutes before it lands. In these minutes the airplane is basically gliding the distance to the ground.
Are you soon going to fly and do you want to know more about the workings of an airplane? Then try to get a window seat at one of the wings. This is a very interesting place to sit, where you can learn more about the workings of an airplane and the way in which an airplane wing is built. Because a lot happens here. At the top, front and backside of the wing you will namely see a lot of parts moving.
Airplane wings have been specifically designed to give the airplane the optimal lift with a normal speed. This is also called the cruising speed. For a jet aircraft this speed is at 850 km per hour. This is of course way too quick to start and land. Besides this, the shape of a wing can differ between the different types of airplanes. This is because every airplane has a different shape, size and weight.
The lift, or the upward force, that an airplane wing supplies, is not only dependent on the speed, but also on the convexity (rounding) of the wing. The convexity of the wing can be changed at the starting and landing, which makes it possible that a wing can still deliver enough force at lower speeds. The pilots can change the convexity with the flaps. These are big pieces at the backside of the wings. These can be extended step by step. Most airplanes also know flaps at the front of the wings. These flaps at the front of the wings are called 'slats'. When you are sitting at the window of a wing, then you will see that the flaps are slowly going into the wing after starting.
During a flight you can also see moving parts at the backside of the wing. These are the ailerons. These parts are used to make a turn and to give the airplane bank angle. With this the rounding of the wings can be adapted, so that there is more lift in one wing than the other. When the airplane is taking a left turn, then the ailerons at the right side go down. The ailerons on the left wing will then go up. In this way more rounding and lift are created.
