About the Science

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Mathematician Daniel Bernoulli formulated a principle, which is now known after its namesake, the Bernoulli’s principle. It states that as the speed of a fluid increases the pressure of a fluid [liquid or gas] will decrease. Within the same fluid, for example air moving over an aircraft wing, high-speed flow creates a low pressure, and low-speed flow creates a high pressure.

Some examples of Bernoulli's Principle in action would be that it is what allows wings to produce lift and planes and helicopters to fly. The shape of an airplane wing or helicopter blade makes air travel a greater distance over the top of the wing or blade than beneath it. This creates a higher pressure beneath the wing or blade than above it. The difference in pressure causes the wing or blade to push upwards and lift is created.

Two other forces can affect flight: drag and thrust. Drag is a force that opposes an aircraft’s motion through the air. It is generated by the interaction or contact of a solid body with a fluid [liquid or gas] where a difference in velocity between the solid object and the fluid creates resistance. Drag acts in the opposite direction of the motion of the aircraft.

This resistance is overcome through a force known as thrust, which allows an aircraft to move through the air. Thrust is a mechanical force generated by a propulsion system commonly known as the engine that must be in physical contact with a working fluid [liquid or gas] to produce thrust. The thrust created by the engines must be greater than drag otherwise the aircraft cannot achieve lift or movement.