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Forces of Flight 101
- Isabella Roquette
- Sep 2
- 3 min read
Updated: Sep 7
Hello Universe!
Today, I'm going to be explaining a basic concept necessary for the understanding of Aerospace Engineering.
Aerospace Engineering
Developing our knowledge of what the universe holds begins with building the equipment needed to go beyond our atmosphere. That’s what aerospace engineers, focused on astronautical engineering, do. This field perfectly combines my passions: engineering,
which encompasses mathematics, science, and imagination, and aerospace, which pivots engineering towards aircraft that can be used for space exploration.
Forces of Flight
To understand Aerospace Engineering and how to design aircraft, it is necessary to know the forces of flight. These are the forces that act on an aircraft while in the air and control its movement.
Weight
This is a force all objects within Earth’s gravitational pull experience. It depends on the total mass of the aircraft and is distributed throughout the plane. It is often thought of as acting through a single point referred to as the center of gravity, around which the aircraft rotates. To fly an aircraft, we must overcome its weight using an opposing force and control it in flight. These are both related to the aircraft’s weight and the position of its center of gravity, which is constantly changing due to the aircraft’s fuel consumption. As a result, the pilot must continuously adjust the controls in order to maintain the plane’s balance.
Lift
This is the opposing force needed to overcome an aircraft’s weight. It is generated by the aircraft’s aerodynamic ability and is directed perpendicular to the flight direction. The magnitude of the lift depends on the aircraft’s shape, size, and velocity. The primary source of lift is generated by the wings but is distributed throughout the aircraft. Lift is generated through a single point known as the center of pressure, defined like the center of gravity but utilizing the pressure distribution around the body. The center of pressure changes location depending on the angle of attack. This lift distribution is important for improving control, as are aerodynamic surfaces.
Drag
While the aircraft moves through the air, there is a resistance force from the air known as drag. It is directed along and contrary to the flight direction. Many factors are considered when measuring the magnitude of the drag force, such as the shape of the aircraft, atmospheric conditions, and the aircraft's velocity. Similarly to life and weight, we collect all of drag’s individual components and combine them into a single drag magnitude. Like lift, drag acts through the center of pressure of the aircraft.
Thrust
Aircraft use a propulsion system to generate a force to overcome drag. Its direction depends on how the engines are attached to the aircraft and their purpose. On certain aircraft, the thrust direction can be varied to help the airplane take off over a short distance. The magnitude of the thrust varies depending on factors related to the propulsion system, including the type and quantity of engines and the throttle setting.
In jet engines, the aircraft thrust is a reaction to hot gas running out of the nozzles (the hot gas goes out the back, and the thrust pushes toward the front - Action/Reaction is explained by Newton’s Third Law of Motion).
The aircraft's movement through the air depends on the strength and direction of the forces mentioned above. If they’re balanced, the aircraft cruises at constant velocity, but if they’re unbalanced, the aircraft accelerates in the direction of the largest force.
Thrust only overcomes drag; what lifts airplanes are their wings, which is why some aircraft, like gliders, have no engines and use some external power source to initiate the motion for the wings to produce lift.
