People have got so used to watching the skies filled with jet trails that we never stop and realise its truly magic that hundreds of tonnes of metal with 500 people aboard can hop across the Atlantic and in a fraction of a day you could be waking up to a new language, new culture or lost in the middle of nowhere!
So how is this even possible? Just a little bit over a hundred years back we were barely experimenting with wooden planes that flew for a few meters up and forward before crashing right back to the ground!
It is easy to take the physics of flight for granted, as well as the ways in which we exploit them to achieve flight. We often watch an aircraft in the sky with no greater understanding of the principles involved than with a caveman.
To answer this question, we have to understand the world of fluid mechanics. Basic aerodynamics means that air is just like a fluid; a matter that has weight and occupies space. The entire atmosphere in which planes fly or propel through is a massive fluid layer. We achieve a certain amount of forces by the use of jets and propellers that thrust the aircraft forward. To achieve flight, we exploit four main aerodynamic forces: Lift, Weight, Thrust and Drag. These are the four forces constantly attached to an aircraft but in different strengths and directions.
The image below here shows these four basic forces and the direction in which they act in.