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Film summary
Aeroplanes use the same forces and physical principles as birds to fly. Discover how man has copied nature to achieve flight.Key facts
- Flight occurs when the upward force (lift) is greater than the downward.
- Flight is explained by Newton's third law.
- Lift is achieved due to the shape of the plane's wing.
- The Wright brothers achieved the first sustained flight in 1903.
Transcript
Evolutionary adaptations allow many animals to fly, but it wasn't until 1903 that man first mastered powered flight when the Wright brothers took to the air.
The Wright Brothers, USA
1900s
It was only possible with an understanding of the forces at work and how to manipulate them.
Gravity
The Earth's gravity acts downwards, pulling an aircraft towards the ground.
To stay in the air it must produce an upward force of at least the same magnitude.
Making aircraft as light as possible reduces the upward force required to reach flight.
Lift
The upward force that keeps a plane in the sky is called lift, and the secret of how it is produced lies in the shape of the wing – the aerofoil, and how air moves over it.
Prof Ian Poll, Cranfield College of Aeronautics, UK – "Underneath the aerofoil the curvature of the aerofoil deflects the air stream downwards. What's perhaps not so intuitive, is that over the top of the aerofoil, the air does not go straight on – what happens in reality, the air over the top surface is also bent. To do that the aerofoil needs to apply a force to the air, needs to push it downwards, by Newton's third law, therefore, the air pushes back on the wing and generates the force that we know as lift."
Newton's third law of motion states that every action has an equal and opposite reaction, so the downward force on the air produces an upward force on the wing.
When this lift is greater than, or equal to, the gravitational pull that Earth exerts on the plane, the plane can fly through the sky.
This same principle is used in all sorts of planes and even helicopters – the engines themselves don't provide the lift, they simply force the aircraft forward or rotate the blades, forcing the air over the aerofoils.
Rather than biological evolution, it's our evolving understanding of physics that has allowed man to take to the skies.
