Heavier-than-air flight is made possible by a careful balance of four physical forces: lift, drag, weight, and thrust. For flight, an aircraft’s lift must balance its weight, and its thrust must exceed its drag. A plane uses its wings for lift and its engines for thrust. Drag is reduced by a plane’s smooth shape and its weight is controlled by the materials it is constructed of.
In order for an aircraft to rise into the air, a force must be created that equals or exceeds the force of gravity. This force is called lift. In heavier-than-air craft, lift is created by the flow of air over an airfoil. The shape of an airfoil causes air to flow faster on top than on bottom. The fast flowing air decreases the surrounding air pressure. Because the air pressure is greater below the airfoil than above, a resulting lift force is created.
Every physical body that is propelled through the air will experience resistance to the air flow. This resistance is called drag. Likewise, an aircraft’s wing is designed to be smooth to reduce drag.
The weight of an aircraft is a limiting factor in aircraft design. A heavy plane, or a plane meant to carry heavy payloads, requires more lift than a light plane. It may also require more thrust to accelerate on the ground. Thrust itself is a force than can best be described by Newton’s second law.
Reflexive Analysis
This article provides insight into the kinds of problems the Wright brothers were trying to solve as well as some basic mechanics of what keeps both birds and planes in the air. The language is not too dense, but is still presented with enough math that the science can be understood. In seeking to educate about flight mechanics and the story of the first flight this information is critical. It also relates birds to airplanes, an important connection to make when connecting the story of the Wright brothers to a more wondrous/natural/romantic idea of flight.
Sources
Theory of flight. (n.d.). https://web.mit.edu/16.00/www/aec/flight.html
