What shape of the wing has the best lift, and what is the principle of wing lift

It is generally a concave-convex airfoil, with high lift but also high drag.

A concave-convex airfoil with a large curvature in the middle arc will have a large lift coefficient, and there is a very typical airfoil --- Cooperfur airfoil. The maximum curvature of the middle arc is reached, and the maximum lift coefficient is 12 degrees at the angle of attack. In order not to increase the resistance too much, the maximum height of the upper arc is only 11%, so the airfoil is extremely thin, and the maximum thickness is only.

It is used in elastic-powered or towed gliders to fly very slowly, but because it is too thin and structurally difficult, there used to be a full inclined rib structure or even an all-solid wood structure, but now almost no one uses it.

It depends on how fast you are.

It's different in different situations.

The principle of wing lift is the difference in air pressure caused by the difference in velocity between the airflow on the upper and lower surfaces of the wing.

Lift is the upward force. The force that makes you rise. There are many kinds of them. Generally said in the air. That is, the upward force is greater than the downward force, and its resultant force can make the object rise.

The difference in air pressure caused by the difference in lift ** in the velocity of the airflow on the upper and lower surfaces of the wing. However, the explanation of the cause of the velocity difference between the upper and lower surfaces of the wing is complicated, and the isochronous theory and fluid continuity theory used in popular science cannot fully explain the cause of the velocity difference. Two-dimensional wing theory is commonly used in the aviation community, which mainly relies on the Kuta condition, the circumference around the wing, the Kuta-Zhukovsky theorem and the Bernoulli theorem.

Lift Applications:

The vast majority of the lift of the aircraft is generated by the wings, the tail usually produces negative lift, and the lift generated by other parts of the aircraft is very small and generally not considered. The principle of lift is that the presence of the ring around the wing (attachment vortex) causes the flow velocity of the upper and lower surfaces of the wing to be different, the pressure is different, and the direction is perpendicular to the relative air flow.

The generation of wing lift mainly depends on the action of the upper surface suction, rather than the effect of the positive pressure on the lower surface, the suction formed on the upper surface of the wing accounts for about 60-80% of the total lift, and the lift formed by the positive pressure on the lower surface only accounts for about 20-40% of the total lift. So it cannot be assumed that the aircraft is supported in the air, mainly as a result of the impact of air from under the wing.

There will be various drags in the air when an airplane flies, and the drag force is the aerodynamic force that is opposite to the direction of the airplane's movement, which hinders the progress of the aircraft, and here we also need to understand it. According to the causes of resistance, it can be divided into friction resistance, differential pressure resistance, induced resistance and interference resistance.

The four types of resistance are for low-speed aircraft, and for high-speed aircraft, in addition to these resistances, other drags such as wave resistance are also generated.

Since Bernoulli's equation is derived from the conservation of mechanical energy, it is only suitable for ideal fluids with negligible viscosity and non-compressibility.

1. The airplane can fly into the sky because the wings are subject to upward lift. The streamline distribution of the air around the wing when the aircraft is flying refers to the asymmetry of the shape of the wing cross-section, the streamline above the wing is dense and the flow velocity is large, and the streamline below is sparse and the flow velocity is small. From Bernoulli's equation, the pressure above the wing is small, and the pressure below is strong.

This creates a lift force in the direction acting on the wing.

2. The sprayer is made by using the principle of large flow rate and low pressure. Let the air flow out quickly from the hole, the pressure near the hole is small, and the air pressure on the liquid level in the container is strong, and the liquid rises up along the thin tube at the bottom of the hole. After flowing out of the upper mouth of the tube, the impact of the air flow is sprayed into a mist.

3. The carburetor of the gasoline engine is the same as the principle of the sprayer. The carburetor is a device that supplies a mixture of fuel and air to the cylinder, and the construction principle refers to the fact that when the piston in the cylinder makes the suction stroke, the air is sucked into the pipe, and when the flow rate is large and the pressure is small when flowing through the narrow part of the pipe, the gasoline flows out of the nozzle installed in the narrow part, and is sprayed into a mist to form an oil-gas mixture into the cylinder.

4. The "spinning ball" in the ball game has great power. The difference in the flight trajectory of a spinning ball and a non-spinning ball is caused by the different air flow conditions around the ball. Do not spin the ball horizontally to the left when moving around the same air streamline.

The above and below of the ball are streamlined symmetrically, the flow velocity is the same, and there is no pressure difference between the top and bottom. Considering the rotation of the ball, the axis of rotation passes through the center of the ball and is parallel to the ground, and the ball rotates counterclockwise.

When the ball rotates, it will drive the air to rotate with it, causing the flow velocity of the air below the ball to increase, the flow velocity above to decrease, the flow velocity below the ball is large, the pressure is small, and the flow velocity above is small and the pressure is strong. Compared to a non-spinning ball, a spinning ball is subjected to a downward force due to rotation, and its flight trajectory is bent downward.

5. The topspin ball represents the table tennis ball, the axis of rotation is perpendicular to the direction of the ball's flight and parallel to the table, and the ball rotates in the counterclockwise direction. Under the same conditions, the topspin ball has a lower flight arc than the non-spinning ball, and the downspin ball is the opposite, the ball rotates in the opposite direction and receives an upward force, which is higher than the flight arc of the non-spinning ball.

6. A pen holder, blow to the big mouth, put a small ball on the small mouth, the small ball can rotate in the air.

7. Put a small ball in the wide part of the funnel, resist it with your hand, blow in the small mouth and let it go at the same time, the streamline above the ball is dense and the flow rate is large, and the streamline below is sparse and the flow rate is small, so the ball will not fall, but will only jump in the funnel.

y=1/2ρcsv�0�5

where c is the lift coefficient, which is related to the shape of the wing and the angle of attack. There is no formula for calculating it, and the relationship between the lift coefficient and the angle of attack of various different wing shapes is obtained by the experimental method to obtain a plot for use.

s is the area of the wing.

v is the speed of the aircraft.

is the density of the atmosphere.

cy = y/(qs)

where cy: lift coefficient.

y: lift (lift is perpendicular to the direction of the velocity of the airflow, positive upward) q: dynamic pressure, q= v*v2 (is the density of the air, v is the velocity of the airflow relative to the object).

s: reference area (the wing area is generally selected as the reference area for aircraft).