What is the formula for calculating the weight of a plane in level flight?

In summary, Bernoulli's principle states that the pressure on the bottom of a wing is inversely proportional to the mass above it.
  • #1
ryanbe
8
0
hi

how do i calc the weight of a plane if it stays in level flight with the air speed on top of the wing 62m/s and the bottom 54m/s. the surface area of the wing is 16m^2
 
Physics news on Phys.org
  • #2
Google "Bernoulli's principle". You'll find that the excess pressure on the bottom of the wing (which you can relate to the weight of the plane, how?) is given by the difference in the kinetic energy densities above and below. The latter is the mass density times the velocity squared. You'll have to look up the density of air, so apparently the plane is not flying at high altitude.

(By the way, this is a cute problem, but it is not an accurate portrayal of the real reason that planes fly, as proven by the fact that this plane could fly upside down. But perhaps it is the maximally efficient flight, and maybe many planes are designed to get close to this limit. The other key design issue is stability.)
 
Last edited:
  • #3
You'd need to know the mass of the affected air. Also the air speed over and under the wing won't be constant, it will vary depending on distance from the wing.

Maybe this is just a simplication of the real issue and just wanting you to use Bernoull as opposed to the actual and complex process of calculating lift.

Also air speed relative to what? It appears to be relative to the wing. Air speed relative to the ambient air would be less, or else this is a very large airplane.
 
  • #4
rcgldr said:
Maybe this is just a simplication of the real issue and just wanting you to use Bernoull as opposed to the actual and complex process of calculating lift.

yes i must use bernoulli but not sure how ?

anybody got the equation in the form that i must use it, then i can take it from there ?
 
  • #5
is this right : p1+1/2*1.29*62^2 = p2+1/2*1.29*54^2

p1 + 2479.38 = p2 + 1880.82
p1 - p2 = 1880.82 - 2479.38
= -598

p = f/a
598= f/16
9568n = f

plane = 975kg
 
  • #6
Looks good to me, though I didn't check the units. Best to include them to make sure.
 

Related to What is the formula for calculating the weight of a plane in level flight?

1. How does the shape of an airplane wing affect its performance?

The shape of an airplane wing, also known as its airfoil, plays a crucial role in determining the lift and drag forces acting on the wing. Depending on the shape, the wing can generate more or less lift, which is necessary for the airplane to stay in the air. A curved or cambered wing shape is commonly used as it creates a pressure difference between the upper and lower surfaces of the wing, resulting in lift.

2. What is the angle of attack and how does it impact an airplane wing?

The angle of attack refers to the angle at which the wing meets the oncoming airflow. It is an important factor in determining the lift and drag forces on the wing. If the angle of attack is too low, the wing may not generate enough lift to keep the airplane in the air. On the other hand, if the angle of attack is too high, it can cause the wing to stall, resulting in a decrease in lift and an increase in drag.

3. How does the speed of an airplane affect the lift and drag forces on the wing?

The speed of an airplane is directly related to the lift and drag forces acting on the wing. As the speed of the airplane increases, the lift force also increases. However, the drag force also increases, making it harder for the airplane to maintain its speed. This is why airplanes need to maintain a certain speed, known as the optimal airspeed, to balance the lift and drag forces and stay in the air.

4. What is the role of air pressure in the physics of an airplane wing?

Air pressure plays a crucial role in the physics of an airplane wing. When air flows over the curved surface of the wing, it creates a difference in air pressure between the upper and lower surfaces. This pressure difference, also known as Bernoulli's principle, is what generates the lift force needed for the airplane to stay in the air. The shape of the wing and the angle of attack also affect the air pressure and, therefore, the lift force.

5. How does the weight of an airplane impact the physics of its wing?

The weight of an airplane can affect the physics of its wing in several ways. First, the weight of the airplane determines the amount of lift needed for it to stay in the air. If the weight is too high, the wing needs to generate more lift, which can increase the angle of attack and potentially lead to a stall. Additionally, the weight distribution on the airplane can affect its stability and control, which can also impact the performance of the wing.

Similar threads

B Airplanes stay level at higher velocities?
    • Other Physics Topics
Replies
3
Views
1K
VTOL RC Airplane Tricopter COG, Liftoff Weight Calculations
    • Aerospace Engineering
Replies
3
Views
2K
How does the weight of airplanes affect atmospheric pressure?
    • Other Physics Topics
2
Replies
56
Views
10K
How Does Drag Affect Airplane Dynamics in a Four-Dimensional Universe?
    • Sci-Fi Writing and World Building
Replies
18
Views
2K
B Airplanes Landing & Altitude Problem
    • Other Physics Topics
Replies
3
Views
1K
How do airplanes fly with heavy weight and air resistance?
    • Other Physics Topics
4
Replies
127
Views
16K
How Bees Fly: Exploring the Physics Behind Their Flight
    • Other Physics Topics
Replies
6
Views
2K
Airplane wings -- How do they work and why do they change shape?
    • Mechanics
3
Replies
81
Views
8K
How to calculate airplane noise as a function of distance?
    • General Engineering
2
Replies
49
Views
6K
Misc. Designing a Model Aircraft: Calculating Thrust and Lift for an Efficient Flight
    • DIY Projects
Replies
9
Views
2K

Hot Threads

Recent Insights

Back
Top