Understanding Lift Force on Airplanes

In summary, the force of lift on an airplane is determined by the lift coefficient, air density, velocity, and lift area of the wings. When using SI units, the force is measured in Newtons. In practicality, the lift force is not the only force acting on the plane, as gravity and drag also play a role. The lift balances the weight of the aircraft in level flight, and is created by the difference in air pressure above and below the wing. To determine accurate lift, the effects of drag and gravity must also be taken into account.
  • #1
Poposhka
7
0
the force of lift excerted on an airplane is defined as
F = Lc * D * v^2 * A
where Lc is the lift coefficient, D is the air density, v velocity, and A the lift area of the wing structure. If i use SI units, the Force is expressed in Newtons.

What I'm trying to grasp here, is how does this apply in practicality?
If i use the numbers Lc = 1.0, D = 1.225, v = 100, A = 21, (not random values) the result is 257,250 N ... now ... what does that MEAN? that the wings on that airplane produces enough lift to accelerate a 2000 kg airframe upwards at 128.6 m/s^2 ? Or, am i not calculating in gravitation? should the correct formula be 257250 / (2000 * 9.8) = 13.1 m/s^2 ? That just seems like an awfully high number... Or is it impossible to determine accurate lift unless you account for drag?

Thanks for any help
-- Pops
 
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  • #2
Remember that lift is not the only force acting, don't forget gravity. The resultant force would be something like;

[tex]F_{total} = F_{lift} - mg[/tex]

~H
 
  • #3
The thrust pushes the plain forward and drag pushes/pulls against the aircraft.

In level flight, the lift balances the weight of the aircraft.

The forward velocity of the aircraft cause the lift as the air passes above and below the wing. The pressure over the wing is slightly less than the air pressure under the wing. In fact, the average differential pressure across the wing of a Boeing 747 is about 1 psi, and there is about 1 in2 of surface area for each lbm (weight of 1 lbf) of plane + load.
 

1. What is lift force and how does it work on airplanes?

Lift force is the upward force generated by an airplane's wings as it moves through the air. This force is created through a combination of the shape and angle of the wings, as well as the speed of the airplane. As the air flows over the curved shape of the wing, it creates an area of low pressure on top and high pressure on the bottom, resulting in lift force.

2. How does the angle of attack affect lift force on an airplane?

The angle of attack refers to the angle at which the wing meets the oncoming air. As the angle of attack increases, so does the lift force. However, if the angle of attack becomes too high, the air can no longer flow smoothly over the wing, causing a decrease in lift force and potentially leading to a stall.

3. What other factors besides wing shape and angle of attack affect lift force?

In addition to the wing shape and angle of attack, factors such as air density, airspeed, and wing surface area also affect lift force. Higher air density and faster airspeed can result in increased lift force, while a larger wing surface area can provide more surface for the air to flow over and generate lift.

4. How do different types of airplanes generate lift force?

Different types of airplanes, such as commercial jets, propeller planes, and gliders, generate lift force in different ways. For example, commercial jets rely on the shape and angle of their wings, as well as the power of their engines, to generate lift. On the other hand, gliders use the power of rising air currents to generate lift and stay aloft.

5. Can lift force be affected by external factors during flight?

Yes, lift force can be affected by external factors such as wind, turbulence, and changes in air temperature. These factors can alter the air flow over the wings and potentially impact the lift force. Pilots must constantly monitor and adjust for these external factors to maintain a safe and steady flight.

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