Gravity

Definition

Gravity is the natural force that attracts two bodies toward each other, depending on their masses and the distance between them. In aviation, gravity plays a crucial role in determining how an aircraft behaves during straight and level flight, climbing, and descending. The balance of gravitational force with other forces like lift, thrust, and drag influences flight performance and stability.

5 Must Know Facts For Your Next Test

1. Gravity pulls all objects toward the center of the Earth, creating a constant downward force on aircraft during flight.
2. In straight and level flight, gravity is balanced by lift, allowing the aircraft to maintain altitude without ascending or descending.
3. When climbing, the pilot must generate enough thrust to overcome both gravity and drag to achieve a positive rate of climb.
4. During descent, gravity increases the aircraft's speed unless countered by increased drag or reduced thrust.
5. The weight of an aircraft is determined by the gravitational force acting on its mass, significantly affecting its performance characteristics.

Review Questions

• How does gravity affect the forces acting on an aircraft during straight and level flight?
  • In straight and level flight, gravity acts downward while lift acts upward. For an aircraft to maintain altitude, these two forces must be equal; thus, gravity must be countered by lift. If lift exceeds gravity, the aircraft will climb, whereas if lift is less than gravity, it will descend. Understanding this balance is essential for pilots to achieve stable flight.
• Discuss how a pilot must adjust thrust when climbing to counteract gravity's influence.
  • When climbing, a pilot must increase thrust to overcome the gravitational pull that acts on the aircraft. Gravity not only opposes the upward movement but also adds to the total drag experienced during ascent. Therefore, achieving a successful climb requires careful management of thrust in relation to both lift and drag to ensure that the aircraft maintains a positive rate of climb.
• Evaluate how changes in weight affect an aircraft's ability to maintain straight and level flight due to gravity.
  • Changes in weight significantly impact an aircraft's ability to sustain straight and level flight because gravity's pull increases with weight. A heavier aircraft requires more lift to balance against gravitational force. If not compensated with increased thrust or improved aerodynamic efficiency, this additional weight can lead to difficulties in maintaining altitude or achieving necessary climb rates. Therefore, understanding how weight affects gravitational force is critical for effective flight management.

Related terms

Lift:

The aerodynamic force that acts perpendicular to the relative wind and supports an aircraft in the air.

Thrust:

The forward force produced by the engines of an aircraft, necessary to overcome drag and enable flight.

Drag:

The aerodynamic resistance experienced by an aircraft as it moves through the air, opposing thrust.