When a ball spins to left, shouldn't it curve right?(hurricane vise)

[beatenbob]

Russ,

First of all, the baseball curves b/c its surface is uneven.
I am talking about a table tennis ball.(high quality ones have internal seam so they are perfectly smooth)

Also, from the article, how come the air hitting the top of the wings of the airplane is faster?

You might have to take look in this article http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

 

[rcgldr]

You might have to take look in this article http://hyperphysics.phy-astr.gsu.edu/hbase/pber.html

In the first pair of diagrams in that article note that it's a closed system. If the pipe in the first diagram has holes in it then the fluid will flow out of the pipe at higher pressure areas, and into the pipe at lower pressure areas, and the amount of mass flowing across any point in the pipe will vary, requiring a dramatic change to the equations involved.

Regarding faster moving air streams corresponding to lower pressures on a aircraft, note that slower civilian aircraft, like a Cessna, have a hole in the side of the fuselage, which experiences a crossflow equal to the true air speed of the aircraft, yet the pressure at the hole is basically the same as the pressure at the surrounding static air. This hole is called a "static" port, and it's connected to an internal chamber. The pressure of the internal chamber is used to indicate the current altitude, and works regardless of the airspeed (within the range of the air speeds a Cessna experiences (0 to about 150mph).

Read the section regarding static ports, air speed and Bernoulli from this link.

http://home.comcast.net/~clipper-108/lift.htm

The article is a bit confusing since it mentions effects very close to the wing surface such as Coanda effect, but then goes on to show the more accurate description of a wing a an "air scoop" with an effectively very large scoop effect.

 

[Skhandelwal]

Hey Jeff, could you please answer my questions above? Thanks a lot.

 

[Roy Dale]

By definition, the reaction force in the direction that the ball moves, slowing it down, is called drag. The reaction force perpendicular to the direction the ball moves, causing it to curve, is called lift.[/QUOTE]

If there were a reaction force in the direction that the ball moves it would not slow it down it would speed it up. Drag is the aerodynamic force in the direction of the relative airflow that caused it and lift is perpendicular to the relative airflow that caused it. You cannot accurately define lift in relation to the motion of the ball because lift does not require the motion of the ball. And any way you are not determining lift by the direction the ball moves you are determining it by the balls motion through the air, this maybe why you think the ball is generating lift. The ball is generating a relative airflow by its motion through the air and its motion while in the air (rotation). Drag not only opposes the motion of the ball through the air it also opposes its rotation, that’s a lot of directions. If the friction drag (reflected in a torque force that opposes rotation) around a spinning ball were to become greater on one side than the other this force will start to become more linear just like a tire pushed into the ground. The spinning ball is pushed into the air by its forward motion. This effect is not as dramatic as a tire but it is enough to make the ball curve. And because the curve is the result of friction drag any surface preparation that increases friction drag (dimples, fuzz, threads) will also increase the Magnus effect.