AboutNed Dolan Expertise 38 years as a professional pilot. Worked as an instructor for a major airline, as a tow pilot towing gliders and flew international routes until 1998. Do not know much about the maintenance end of the business.
Experience Teaching new Captains the skills and knowledge needed to
occupy the position.
Helping develop procedures for use in a new airplane
type. (B757)
Ground effect has been described to me simply as a bubble of air, and that seems to be what the FAA Examiner was looking for during my Private checkride. Could you possibly redefine ground effect for me or elaborate on this childish definition that has been taught to me. I also have a question on the topic of lift. You and I both know that when a fluid passes through a venturi its velocity increases and pressure decreases. This is the way, I have been taught, a wing works: the air moves over the top surface of the wing at a higher speed than the air passing under than bottom of the wing which creates lower pressure on top while the air passing on the underside of the wing remains at a higher pressure lifting the wing into the air. It is said that the top curvature is acting as the bottom half of a venturi. My question to you is; what then is acting as the top half of the venturi to cause the air to move at such a higher speed over the wing?
Furthermore in the case of an airplane with a symmetric wing where the camber of the wing is equal on top and bottom, how is the lift being generated in that case?
Thank you for you time,
John
Answer Hi John, Ground effect is caused by the interference of the ground or water surface beneath the aircraft with the normal airflow patterns about a wing in flight. Ground effect normally is experienced at a height that is approximately equal the length of the wing span.
It results in an increase in lift due to the compression of the air between the wings and the surface. It is to take advantage of ground effect the we take off in rough field conditions at a lower than normal airspeed and then level off to accelerate while still in the ground effect before starting to climb.
Aerodynamics is not my strong point, but I will try to anwer your second question by saying that the symmetrical shaped wing produces lift as a result of the angle of attack whether inverted or not. As the angle of attack changes the velocity of flow over the top of the wing (which ever side that happens to be) causes lift the same way a non symmetrical wing does.
