# What is the relationship of lift drag thrust and weight

The Four Forces

An airplane in flight is always in the middle of a tug-of-war with the four forces. For an airplane to takeoff, thrust must be greater than drag and lift must be greater than weight. To maintain level flight, lift must equal weight and thrust must equal drag. For landing, thrust must be less than drag, and lift must be less than weight. Drag opposes thrust, and acts rearward parallel to the relative wind. In steady and level flight: The WEIGHT is balanced by the LIFT, The DRAG is balanced by the THRUST. The airplane will continue flying at the same velocity, i.e. at the same speed and in the same direction.

If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user. The atmosphere the air is the medium in which an aircraft operates.

It is the properties of the air, changed by the shape of the wing, that generate the required lift force. Typically, the forces created during aircraft operation are arranged as illustrated below. They do not act through a common point. The center of pressure lies a short distance aft of the how to edit music information on android of gravity.

Since lift and weight do not act in the same line, they make up what is known as a couple. This couple has a turning effect on the aircraft, pitching the nose downwards. The thrust and drag forces constitute an opposite couple, the effect of which is to pitch the nose upwards.

Thus, the two couples generally cancel each other out. Lift is a force which opposes the downward force of weight. It is produced by the dynamic effect of the air acting on the airfoiland acts perpendicular to the flightpath through the center of lift. Drag is a rearward, retarding force caused by disruption of airflow by the wing, rotor, fuselage, and other protruding objects.

Drag opposes thrust, and acts rearward parallel to the relative wind. The airplane will continue flying at the same velocity, i. If during steady and level flight, thrust is increased, then the aircraft will start to accelerate in the direction of thrust will start to gain speed.

The increase in speed will lead to increase in drag. In the reverse situation, when during steady and level flight thrust is reduced, the aircraft will start to accelerate in the direction of drag the speed will start to decrease.

The decrease in speed will lead to a decrease in drag. Drag is the price paid to obtain lift. The shape of an airfoil and other lift producing devices i.

Since the glide ratio is based only on the relationship of the aerodynamics forces acting on the aircraft, aircraft weight will not affect it. The only effect weight has is to vary the time that the aircraft will glide for.

The heavier the aircraft is, the higher the airspeed must be to obtain the same glide ratio. Both aircraft will cover the same distance but the lighter one will take a longer time to do so. From the practical point of view one should remember that although it is well known that winglets reduce drag and save fuel, their effect on speed control may not have been highlighted before. Crews therefore need to be aware that reduced drag makes speed control on the approach more difficult.

Drag will also increase if the landing gear or flaps are extended and the airspeed will then decrease unless the pitch attitude is reduced. When pitch is reduced, the glide angle increases and the distance traveled will reduce. Return to Toolkit Main Page.

Educator Features

What is the relationship of lift, drag, thrust, and weight when the airplane is in straight-and-level flight? Lift equals weight and thrust equals drag One of the main functions of flaps during approach and landing is to ________. What is the relationship of lift, weight, thrust, and drag when the airplane is in straight-and-level flight? A. Lift equals weight and thrust equals drag B. Lift, drag, and weight equal thrust C. Lift and weight equal thrust and drag. What is the relationship of lift, drag, thrust, and weight when the airplane is in straight and level flight. Lift equals weight and trust equals drag. When operating an unmanned airplane, the remote pilot should consider that the load factor on the wings maybe increased any time. The airplane is subject to maneuvers other than staright and level flight.

When an airplane is flying straight and level at a constant speed, the lift it produces balances its weight, and the thrust it produces balances its drag. However, this balance of forces changes as the airplane rises and descends, as it speeds up and slows down, and as it turns.

A spacecraft has weight, even in orbit, and uses thrust to reach space and to maneuver. But lift and drag—both created by movement through air—are absent in the near vacuum of space.

A force is basically a push or a pull that causes an object to undergo a change in speed, a change in direction, or a change in shape.

A force has both magnitude size and direction. An airplane in flight is always in the middle of a tug-of-war with the four forces. For an airplane to takeoff, thrust must be greater than drag and lift must be greater than weight. To maintain level flight, lift must equal weight and thrust must equal drag. For landing, thrust must be less than drag, and lift must be less than weight.

Forces of Flight on this Page. The Four Forces. It acts in a downward direction—toward the center of the Earth. Lift is the force that acts at a right angle to the direction of motion through the air. Lift is created by differences in air pressure. Thrust is the force that propels a flying machine in the direction of motion. Engines produce thrust. Drag is the force that acts opposite to the direction of motion. Drag is caused by friction and differences in air pressure. All Four Forces Act on an Airplane When an airplane is flying straight and level at a constant speed, the lift it produces balances its weight, and the thrust it produces balances its drag.

Only Two Forces Affect a Spacecraft in Space A spacecraft has weight, even in orbit, and uses thrust to reach space and to maneuver. Two Forces Affect Spacecraft in Space. Ask an Explainer Q: What is a force? A: A force is basically a push or a pull that causes an object to undergo a change in speed, a change in direction, or a change in shape.

Did You Know? Pop Quiz Which of these forces is a field force?